The present invention, by hot forging crankshaft for 3-cylinder engine (hereinafter, also referred to as "forged crankshaft") it relates to a technology for producing. In particular, three cylinders including in the manufacturing process of the forged crankshaft, molding apparatus for molding a material for out finishing subjected to finishing strike to shape the final shape of the forged crankshaft, and a preliminary molding step using the molding device the method of manufacturing a forged crankshaft engine.
BACKGROUND
[0002]
　It began passenger, motorcycle, in an engine, such as agricultural machinery, require crankshaft to retrieve power by converting the reciprocating motion of the piston into rotary motion. Crankshaft, and those manufactured by forging, but are roughly divided into those produced by casting, dominant former forged crankshaft strength and rigidity are often used. In recent years, because of the response to enhance the emission control fuel efficiency, has accelerated the engine capacity of downsizing, 3-cylinder engine has attracted attention.
[0003]
　Generally, forging crankshaft for 3-cylinder engine, cross section and the raw material cross-sectional area constant billet over the entire length in the round or square, is produced through preformed die forging, the steps of burrs vent and shaping in order . Preforming step includes the steps of stamping and bending roll forming, die forging step comprises the steps of rough hitting the finishing strike.
[0004]
　Figure 1 is a schematic diagram for explaining a conventional typical three-cylinder engine forged crankshaft manufacturing process. Crankshaft 1 illustrated in Figure 1, 3 is intended to be mounted on cylinder engine, four journal portions J1 ~ J4,3 one pin portions P1 ~ P3, the front portion Fr, flanges Fl, and the journal portion J1 ~ six crank arm connecting the J4 and pin P1 ~ P3, respectively (hereinafter, simply referred to as "arm") composed of A1 ~ A6. The crankshaft 1, of six arm portions A1 ~ A6, the first and second arm portions connected to the first and third pin portions P1, P3 of the ends A1, A2 and fifth and sixth arm portion A5 a crankshaft of the third cylinder -4 Like counterweight having a balance weight to A6. Third and fourth arm portions A3, A4 connected to the second pin portion P2 of the central, since it does not have a balance weight, the shape of the oval. Hereinafter, the journal portion J1 ~ J4, pin P1 ~ P3, and will be collectively each arm A1 ~ A6, the sign, in the journal portion "J", a pin portion "P", "A" in the arm portion It referred to as. The arm portion having a balance weight, when distinguished from the arm portion having no balance weight, also referred to as Weighted arm. On the other hand, the arm portion having no balance weight is the weight without arm, or also referred to as oval arm.
[0005]
　In the manufacturing method shown in FIG. 1, forged crankshaft 1 is manufactured as follows. First, after heating the billet 2 shown in FIG. 1 (a) cut in advance into a predetermined length by a heating furnace, performing roll forming. The roll forming process, for example, while squeezing and rolling a billet 2 by grooved roll allocate its volume in the longitudinal direction, forming a roll wasteland 103 as the intermediate material (see Figure 1 (b)). Next, in the bending beating process, the roll wasteland 103 obtained by roll forming partially pressing pressure from the longitudinal direction perpendicular to allocate its volume, forming the bending wasteland 104 becomes further intermediate material (see FIG. 1 (c)).
[0006]
　Subsequently, the rough beating step, bending and press forging using a pair of molds and the resulting bent wasteland 104 up and down by beating, forging 105 the approximate shape are shaped in a crank shaft (final forged product) molding (refer to FIG. 1 (d)). Furthermore, the finishing beating step is subjected is rough forged material 105 obtained by rough stamped, pressed forging using a pair of molds in a vertical rough forged material 105, shape matching the crankshaft is shaped forged molding a timber 106 (see FIG. 1 (e)). When these rough beating and finishing beating, from between the parting surface of the mold facing each other, excess material flows out as a burr. Therefore, the rough forged material 105 and the finishing forging 106, respectively burr 105a around the shaped crank shaft, 106a are attached increases.
[0007]
　The burr punching process, while maintaining the mold the finish forged material 106 with the burr 106a obtained by finishing beating from above and below, to remove punching burrs 106a by blade type. Thus, as shown in FIG. 1 (f), forged crankshaft 1 can be obtained. The shaping step, the key point of the forged crankshaft 1 removal of the burr (e.g., a journal portion J, the pin portion P, the front portion Fr, the shaft portion such flange portions Fl and the like, the arm portion A in some cases) mold from above and below in slightly and press, to correct to the desired size and shape. Thus, forged crankshaft 1 is manufactured.
[0008]
　Incidentally, when the adjustment of the arrangement angle of the pin portion P is needed, after the burr punching process, twisting process is added.
[0009]
　Incidentally, in this manufacturing method, since an unnecessary burr not a product is produced in large quantities, undeniable decrease in yield. Therefore, in producing forged crankshaft, conventionally, minimizing the occurrence of burrs, is possible to achieve improvement in yield has become an issue of paramount. The prior art for this problem is the following.
[0010]
　For example, JP 2008-155275 (Patent Document 1) and JP 2011-161496 (Patent Document 2) is shaped journal portion and the pin portion, producing a crankshaft arm portions also be shaped as such the technology disclosed. In Patent Document 1 technique, a portion corresponding to the journal portion and the pin portion of the crankshaft from a material round rod of stepped constricted individually. Then, a pair of journal portions corresponding parts between which the pin portion corresponding parts are gripped by the die. From this state, give compressive deformation to a round bar stock is brought closer to both die in the axial direction. With this variant applied, against a punch in the pin portion corresponding parts in the axial direction and a direction perpendicular to the eccentric pin portion corresponding parts. Sequentially repeating this operation over all of the crank throw.
[0011]
　The technique of Patent Document 2, the mere round bar as a material. Then, while fixed to one of opposite ends of the round bar material holds each other of movable type, a journal portion corresponding portions of the round bar material in the journal-type, a pin portion corresponding parts in the pin type each holds. In this state, the movable mold, apply a compressive deformation into a round bar stock is moved axially toward the fixed journal type and pin type. The deformation applied at the same time, to move the pin-type axially perpendicular direction of eccentricity is eccentric pin portion corresponding portion.
[0012]
　In Patent Documents 1 and 2 either technique, since the burr is not generated, it can be expected a significant improvement in yield.
CITATION
Patent Document
[0013]
Patent Document 1: JP 2008-155275 Patent Publication
Patent Document 2: JP 2011-161496 JP
Summary of the Invention
Problems that the Invention is to Solve
[0014]
　As described above, the technique disclosed in the Patent Documents 1 and 2 is for forming the material of the rod suddenly the crankshaft shape. However, forged crankshaft so high strength and high rigidity is required, the material is difficult to deform. Therefore, the crankshaft that can actually be produced, thicker the thickness of the arm portion, eccentricity of the pin portion is also forced to not give become small, are limited to relatively slow crankshaft shape. Moreover, the arm portion may be of a simple shape without the balance weight to all, i.e. limited to oval arm.
[0015]
　Further, in the technique disclosed in the Patent Documents 1 and 2, the arm portion includes a free expansion in the axial direction and a direction perpendicular with the compressive deformation in the axial direction of the round bar material, the pin portion corresponding portions of the round bar material It is shaped by the eccentricity move in accompanying tensile deformation. Thus, the contour shape of the arm portions tend to be irregular, it can not be secured dimensional accuracy.
[0016]
　The present invention has been made in view of the above problems. An object of the present invention may yield a forged crankshaft for 3-cylinder engine, moreover, in order to manufacture with high dimensional accuracy regardless of its shape, in the process of manufacturing the forged crankshaft, finish shaping the final shape out on the assumption that perform, and to provide a molding apparatus for molding materials for out finishing subjected to the finishing strike. Another object of the present invention may yield a forged crankshaft for 3-cylinder engine, moreover, it is to provide a production method capable of producing with high dimensional accuracy regardless of its shape.
Means for Solving the Problems
[0017]
　Forming apparatus according to an embodiment of the present invention, 3 in the process of producing the forged crankshaft for cylinder engine, the material for out finishing subjected to finishing strike to shape the final shape of the forged crankshaft, an apparatus for shaping the crude material is there.
　Forged crankshaft has no balance weight to the third and fourth crank arm connected to the second pin of the central, it has a balance weight to the remainder of the crank arm.
　The crude material is
　each journal portion and the axial length of the same rough journal portion of the forged crankshaft,
　each pin portion and the axial length is the same coarse pin portion of the forged crankshaft,
　a third forging crankshaft and a fourth said crank arm in response to the crank arm and the axial thickness identical third and fourth coarse crank arm portion,
　the corresponding to the weight with the crank arm having a balance weight forged crankshaft having an axial thickness is thick Weighted crude crank arm portion than the crank arm portion.
　Molding device of the material for finishing out for 3-cylinder engine forged crankshaft according to the present embodiment further includes the following configuration (1) or (2).
[0018]
　(1) Crude pin portion of the crude material, eccentricity of the axial perpendicular direction less than eccentricity of the pin portion of the forged crankshaft.
　Molding device comprises a reference pin type below, the movable pin type, a fixed journal type, a movable journaled, the.
　Reference pin type is disposed at a position of the second coarse pin portion, with addressed to the rough pin portion is cracked, while being in contact with the third and the side surface of the fourth coarse crank arm portion leading to the rough pin, axial constrained movement, moves in the axial direction and perpendicular.
　Movable pin type, is disposed in the first and third coarse pin portions of the respective positions of both ends, with addressed cracking each said coarse pin, each of which contacts the side surface of the rough crank arm portion leading to the rough pin portion while being moved in the axial direction and axially perpendicular direction toward the reference pin type.
　Fixed journal type is disposed at a position of rough journal portion connected to the third and fourth coarse crank arm holds sandwiched individually the crude journal portion in the axial direction and perpendicular, respectively third and while in contact with the side surface of the fourth coarse crank arm portion is constrained to movement in the axial direction.
　Movable journal types are disposed in the third and fourth coarse journal portions of each position other than crude journal portion leading to coarse crank arm holds sandwiched individually the crude journal portion in the axial direction and a direction perpendicular , each, while in contact with the side surface of the rough crank arm portion leading to the rough journal portion, moves axially toward the reference pin type.
　The molding apparatus, a crude journal portion held by sandwiching with a fixed journal type and movable journaled, the reference pin-type and movable pin types from destined wants state to the rough pin portion to move the movable journaled axially with, at the same time to move the movable pin type while moving in the axial direction in the axial direction and the direction perpendicular to move the reference pin-type axially perpendicular direction. As Accordingly, by pressing with reducing its thickness nipped the Weighted crude crank arm portion in the axial direction until the thickness of the weight with the crank arm portion of the forged crankshaft, the crude pin portion axially perpendicular direction increasing the eccentric amount to the eccentricity of the pin portion of the forged crankshaft.
[0019]
　In the molding apparatus of the above (1), the reference pin-type and the movable pin type, wherein the side on which the reference pin type and the movable pin mold was We have addressed in the rough pin portion respectively disposed outside the opposite It includes an auxiliary pin-type, the movable journaled, and the moves to an auxiliary pin-type axial direction forming the movable pin type and the movable pin type and pair with the movable journal type, and the reference pin mold, after the gap between the movable pin type and the auxiliary pin type is closed, so that the rough pin portion for pressing deformation reaches the auxiliary pin-type, in the axial direction perpendicular to the direction of the movable pin type it is preferable to adopt a configuration in which the movement of which is controlled.
[0020]
　In this molding apparatus, the time when the when the total distance traveled in the axial direction perpendicular to the direction of movable pin type was 100%, the movement in the axial direction of the movable journaled adjacent to the movable pin type is completed in moving distance to the movable pin type axial perpendicular direction is 90% or less of the total travel distance, the movement to the movable pin type axial direction perpendicular to the structure completed after this it is preferable.
[0021]
　Further, in the molding apparatus of the above (1), the reference pin-type, the movable pin type, the fixed journal type and the movable journal type, axially perpendicular direction to allow pressure press machine along the direction attached are, addressed with the pressure of the press, with the fixed journal type and the movable journal type holding sandwich the crude journal portion, the reference pin-type and the movable pin type in the rough pin portion Gaware directly with to continue the reduction of the press, at the same time when the movable journaled moves axially by the individual wedge mechanism, along with the movement of the movable journal type, the movable pin type individual it can be configured to move in the axial direction.
[0022]
　In this molding apparatus, differ from each other is preferable in each wedge angle of the wedge mechanism of the movable journaled. Further, the reference pin-type and the movable pin type is connected to the hydraulic cylinder, it is preferable to adopt a configuration that moves by driving of the hydraulic cylinder in the axial direction and perpendicular.
[0023]
　(2) the first and third coarse pin portion at both ends of the coarse material, than √3 / 2 of the eccentricity of the pin portion of the forged crankshaft in the axial direction and amount of eccentricity perpendicular directions opposite to each other small. The second coarse pin portion of the central crude material, eccentricity of the axial direction perpendicular zero, or the pin portion of the forged crankshaft in a first and a direction perpendicular to the eccentric direction of the third coarse pin portion is the same as the amount of eccentricity.
　Molding device comprises a reference pin type below, the movable pin type, a journal type, the.
　Reference pin type is disposed at a position of the second coarse pin portion, with addressed to the rough pin portion is cracked, while being in contact with the third and the side surface of the fourth coarse crank arm portion leading to the rough pin, axial It is constrained the movement of.
　Movable pin type, is disposed in the first and third coarse pins of each position, the addressed cracking each said coarse pin, each, while in contact with the side surface of the rough crank arm portion leading to the rough pin portion , moves in the axial direction and axially perpendicular direction toward the reference pin type.
　Fixed journal type is disposed at a position of rough journal portion connected to the third and fourth coarse crank arm holds sandwiched individually the crude journal portion in the axial direction and perpendicular, respectively third and while in contact with the side surface of the fourth coarse crank arm portion is constrained to movement in the axial direction.
　Movable journal types are disposed in the third and fourth coarse journal portions of each position other than crude journal portion leading to coarse crank arm holds sandwiched individually the crude journal portion in the axial direction and a direction perpendicular , each, while in contact with the side surface of the rough crank arm portion leading to the rough journal portion, moves axially toward the reference pin type.
　The molding apparatus, a crude journal portion held by sandwiching with a fixed journal type and movable journaled, the reference pin-type and movable pin types from destined wants state to the rough pin portion to move the movable journaled axially together, so while moving the movable pin type axially moved axially perpendicular direction. Thus, the reduced to the thickness of the weight with the crank arm portion of the thickness forged crankshaft nipped the Weighted crude crank arm portion in the axial direction, the first and third coarse pin portion in the axial direction and a direction perpendicular in increasing its eccentricity amount to √3 / 2 of the eccentricity of the pin portion of the forged crankshaft presses in opposite directions.
[0024]
　Manufacturing method according to an embodiment of the present invention is a method for producing a forged crankshaft for 3-cylinder engine, comprising any one of the following configurations (3) to (6).
[0025]
　(3) manufacturing method includes a first preforming step described below, the second preforming step, and the finishing beating process, a series of steps.
　First preforming step, shaping the crude material to be subjected to molding apparatus of the above (1). The first and third coarse pin portion at both ends of the rough material is the same as √3 / 2 of the eccentricity of the pin of the axial direction perpendicular forged crankshaft eccentricity is in the opposite direction to each other. The second coarse pin portion of the central crude material, eccentricity of the pin portion of the forging crankshaft direction eccentricity of the axial perpendicular direction perpendicular to the first and eccentric direction of the third coarse pin portion less than.
　Second preforming step, using a molding apparatus of the above (1), molding the material for out finish. For out finishing material, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped.
　Finish beating process is to strike the finishing material for the finishing out, the final shape of the forged crankshaft including an arrangement angle of the pin portion is molded finish that is shaped.
[0026]
　(4) manufacturing method includes a first preforming step described below, the second preforming step, finishing beating process, and twisting process, a series of steps.
　First preforming step, shaping the crude material to be subjected to molding apparatus of the above (1). The first and third coarse pin portion at both ends of the coarse material, eccentricity of the axial perpendicular direction less than eccentricity of the pin portion of the forged crankshaft in the same direction. The second coarse pin portion of the central crude material, from eccentricity of eccentricity of the axial direction perpendicular pin portion of the forged crankshaft in the opposite direction as the first and eccentric direction of the third coarse pin portion It is also small.
　Second preforming step, using a molding apparatus of the above (1), molding the material for out finish. For out finishing material, the final shape of the forged crankshaft except placement angle of the pin portion is shaped.
　Finish beating process is to strike the finishing material for the finishing out, the final shape of the forged crankshaft except placement angle of the pin portion is molded finish that is shaped.
　Twisting step, it adjusts the arrangement angle of the pin portion of the finish to the arrangement angle of the pin portion of the forged crankshaft.
[0027]
　(5) production process comprises first preforming step described below, the second preforming step, and the finishing beating process, a series of steps.
　First preforming step, shaping the crude material to be subjected to molding apparatus of (2). The first and third coarse pin portion at both ends of the coarse material is smaller than √3 / 2 of the eccentricity of the pin portion of the forged crankshaft in the axial direction and amount of eccentricity perpendicular directions opposite to each other. The second coarse pin portion of the central crude material, eccentricity of the axial perpendicular direction is zero.
　Second preforming step, using a molding apparatus of the above (2), molding the material for out finish. The first and third coarse pin portion at both ends of the material for the strike finishing is the same as √3 / 2 of the eccentricity of the pin of the axial direction perpendicular forged crankshaft eccentricity is in the opposite direction to each other is there. The second coarse pin portions of the central element for striking finish is eccentricity of the axial perpendicular direction remains the same as the crude material.
　Finish beating step is to strike finishing the first and third coarse pin portion at both ends of the material for the finishing out while the horizontal posture to press all the crude pin portion axially perpendicular direction, the pin the final shape of the forged crankshaft including an arrangement angle parts are molded finish that is shaped.
[0028]
　(6) manufacturing method includes a first preforming step described below, the second preforming step, and the finishing beating process, the series of steps.
　First preforming step, shaping the crude material to be subjected to molding apparatus of (2). The first and third coarse pin portion at both ends of the coarse material is smaller than √3 / 2 of the eccentricity of the pin portion of the forged crankshaft in the axial direction and amount of eccentricity perpendicular directions opposite to each other. The second coarse pin portion of the central crude material, eccentricity of the pin portion of the forging crankshaft direction eccentricity of the axial perpendicular direction perpendicular to the first and eccentric direction of the third coarse pin portion is the same as that.
　Second preforming step, using a molding apparatus of the above (2), molding the material for out finish. The first and third coarse pin portion at both ends of the material for the strike finishing is the same as √3 / 2 of the eccentricity of the pin of the axial direction perpendicular forged crankshaft eccentricity is in the opposite direction to each other is there. The second coarse pin portions of the central element for striking finish is eccentricity of the axial perpendicular direction remains the same as the crude material.
　Finish beating step is to strike finishing the first and third coarse pin portion at both ends of the material for the finishing out while the horizontal position, pressing the first and third coarse pin portion axially perpendicular direction and, the final shape of the forged crankshaft including an arrangement angle of the pin portion is molded finish that is shaped.
The invention's effect
[0029]
　Forming apparatus of this embodiment, and according to the manufacturing method including a pre-forming step using the same, from no burrs crude material Weighted arm at a thickness of the arm portion be thin three-cylinder engine forged crank shape roughly matching the shape of the shaft, it is possible to form the material for out finish without burrs. If out finishing such finishing out for material no burr, but has some burrs occur, it is possible to manufacture a final shape of the forged crankshaft including a contour shape of the arm portion. Therefore, good yield forged crankshaft for 3-cylinder engine, moreover, it is possible to manufacture with high dimensional accuracy regardless of its shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030]
[1] Figure 1 is a schematic diagram for explaining a conventional typical three-cylinder engine forged crankshaft manufacturing process.
FIG. 2 is the manufacturing method of the first embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and finishing each shape of finish after beating schematically It illustrates.
FIG. 3 is a schematic diagram showing a manufacturing process of a forged crankshaft in the first embodiment.
[4] FIG. 4 is a longitudinal sectional view showing the structure of the molding apparatus in the first embodiment.
[Figure 5A] Figure 5A is a longitudinal sectional view for explaining a method of molding the material for out finishing by molding device of the first embodiment shown in FIG. 4, showing the molding initial state.
[Figure 5B] Figure 5B is a longitudinal sectional view for explaining a method of molding the material for out finishing by molding device of the first embodiment shown in FIG. 4, showing a state during molding completed.
FIG. 6 is a diagram for explaining a situation where the chewing out occurs in the molding of finishing out for the material by the molding apparatus.
[7] FIG. 7 is a diagram for explaining a situation when subjected to countermeasures out chewy molding finishing out for the material by the molding apparatus.
[8] FIG. 8 is a manufacturing method of the second embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, finishing beating after the finish, and twisting after the twisting shaping finish each shape of the wood is a diagram schematically illustrating.
[9] FIG. 9 is a schematic view showing a manufacturing step of forging the crank shaft in the second embodiment.
[10] FIG 10 is a longitudinal sectional view showing the structure of the molding apparatus in the second embodiment.
FIG 11A] FIG 11A is a longitudinal sectional view for explaining a method of molding the material for out finishing by molding device of the second embodiment shown in FIG. 10, showing a molding initial state.
FIG 11B] FIG 11B is a longitudinal sectional view for explaining a method of molding the material for out finishing by molding device of the second embodiment shown in FIG. 10, showing a state during molding completed.
[12] FIG. 12 is the manufacturing method of the third embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and finishing each shape of finish after beating schematically It illustrates.
[13] FIG 13 is a schematic diagram showing a manufacturing process of a forged crankshaft in the third embodiment.
[14] FIG 14 is a longitudinal sectional view showing the structure of the molding apparatus in the third embodiment.
[Figure 15A] Figure 15A is a longitudinal sectional view for explaining a third method of forming the finishing out for the material by the molding apparatus of the embodiment shown in FIG. 14, showing a molding initial state.
[FIG. 15B] FIG 15B is a longitudinal sectional view for explaining a third method of molding the material for out finishing by molding apparatus of the embodiment shown in FIG. 14, showing a state during molding completed.
[16] FIG. 16 is the manufacturing method of the fourth embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and finishing each shape of finish after beating schematically It illustrates.
[17] FIG 17 is a schematic view showing a manufacturing step of forging the crank shaft in the fourth embodiment.
DESCRIPTION OF THE INVENTION
[0031]
　In the present invention, upon producing a forged crankshaft for 3-cylinder engine, it is assumed to perform the finish beating in the manufacturing process. Molding apparatus of the present invention is a finishing beating of the previous step, is used to mold the crude material material for out finishing subjected to the finishing strike. Hereinafter, finishing out material for molding apparatus for forging crankshaft for 3-cylinder engine of the present invention and a 3-cylinder manufacturing method for an engine for a forged crankshaft comprising preforming process using the same, detailed embodiments thereof to.
[0032]
　1. First Embodiment
　1-1. Crude material, for out finishing material, and finish
　Figure 2 is the manufacturing method of the first embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and the finishing beating after the finish each shape of a diagram schematically showing. Figure 2 shows a situation in the case of producing the crankshaft of the three-cylinder -4 Like counterweight. Further, in FIG. 2, for easy understanding of the shape of each step, shown side by side and a plan view showing the external appearance, the layout of the pin portion when viewed along the axial direction.
[0033]
　As shown in FIG. 2, the crude material 4 of the first embodiment, a coarse crankshaft shape as a whole, while relying on the shape of the forged crankshaft 1 of 3 cylinders -4 Like counterweight shown in FIG. 1 (f) is there. The crude material 4, connecting four rough journal portion J1a ~ J4A, 3 single coarse pin portions P1a ~ P3a, crude front portion Fra, crude flange FIa, and coarse journals J1a ~ J4A and coarse pin portion P1a ~ P3a, respectively six crude crank arm portion (hereinafter, simply referred to as "coarse arm") consists A1a ~ A6a. Third and fourth coarse arm portion A3a leading to the center of the second coarse pin portion P2a, A4a, since it does not have a balance weight, the shape of the oval. The crude material 4 Bali does not have. Hereinafter, crude journal portion J1a ~ J4A crude material 4, crude pin portion P1a ~ P3a, and will be collectively each coarse arm portions A1a ~ A6a, the sign "Ja" in the rough journal portion, in the rough pin " Pa ", referred to as" Aa "in the rough arm portion. The first has a balance weight, the second, fifth and sixth coarse arm A1a, A2a, A5a, A6a is also referred to as Weighted coarse arm portion Aa. On the other hand, the third and fourth coarse arm portion A3a having no balance weight, A4a is weight without coarse arm Aa, or also oval coarse arm Aa say.
[0034]
　The finishing out for material 5 of the first embodiment, the above crude material 4, details of which are molded by a molding device to be described later. The material 5 for beating finishing, four rough journal portion J1b ​​~ J4B, 3 single coarse pin portions P1b ~ P3b, crude front portion Frb, crude flange FLB, and the crude journal portion J1b ​​~ J4B coarse pin portion P1b ~ P3b six crude crank arm portion connecting each (hereinafter, simply referred to as "coarse arm") composed of A1b ~ A6b. Third and fourth coarse arm portion A3b leading to the center of the second coarse pin unit P2b, A4b, since it does not have a balance weight, the shape of the oval. It is to hit the material for 5 finish Bali does not have. Hereinafter, will be collectively rough journal portion J1b ​​~ J4B for out finishing material 5, crude pin portion P1b ~ P3b, and each coarse arm portion A1b ~ A6b, the sign, "Jb" in rough journal portion, rough pin portion in it referred to as "Pb", "Ab" in the rough arm portion. The first has a balance weight, the second, fifth and sixth coarse arm A1b, A2b, A5b, A6b is also referred to as Weighted coarse arm Ab. On the other hand, the third and fourth coarse arm portion A3b having no balance weight, A4b may wait without coarse arm Ab, or also oval coarse arm Ab say.
[0035]
　Finish 6 in the first embodiment is obtained by beating finishing materials 5 for beating finishing above. Finish 6, four journal portions J1c ~ J4c, 3 one pin portion P1c ~ P3c, front portion Frc, flange Flc, and the journal portion J1c ~ J4c a pin portion P1c ~ P3c six crank arm portion connecting each (hereinafter, simply referred to as "arm portion") consists of A1c ~ A6c. Third and fourth arm portions A3c leading to the center of the second pin portion P2c, A4c, since it does not have a balance weight, the shape of the oval. Hereinafter, the journal portion J1c ~ J4c the finish 6, the pin portion P1c ~ P3c, and will be collectively each arm portion A1c ~ A6c, the sign, in the journal portion "Jc", "Pc" in the pin portion, the arm portion in referred to as "Ac". The first has a balance weight, the second, fifth and sixth arm portion A1c, A2c, A5c, A6c is also referred to as Weighted arm Ac. On the other hand, the third and fourth arm portions A3c no balance weight, A4c is weight without arm Ac, or also oval arm Ac say.
[0036]
　The shape of finish 6 is consistent with the shape of the crankshaft including the placement angle of the pin portion Pc (final forged product), equivalent to forging the crank shaft 1 shown in FIG. 1 (f). That is, the journal portion Jc of finish 6, the journal portion J and the axial length of the forged crankshaft final shape is the same. Pin portion Pc of the finish 6, the pin portion length P and the axial direction of the forged crankshaft final shape is the same. Further, the pin portion Pc of the finish 6, compared pin portion P of the forged crankshaft final shape, a eccentricity of the axial direction perpendicular the same, the arrangement angle is also the same 120 °, the normal position It is located in. Arm of the finish 6 Ac is the arm portion A and the axial thickness of the forged crankshaft final shape is the same.
[0037]
　The shape of the finishing out for material 5 is generally matched to the shape of the finish 6, just corresponds to the portion excluding the burr 105a of rough forged material 105 shown in FIG. 1 (d). That is, the coarse journal portion Jb finishing out for material 5, the axial length (journal Jc of finish 6) journal portion J of the forged crankshaft final shape is the same. Crude pin portion Pb of the finishing out for material 5, the axial length (pin portion Pc of the finish 6) the pin portion P of the forged crankshaft final shape is the same. Further, the pin portion Pb of the finishing out material for 5, to the pin portion P of the forged crankshaft final shape, a eccentricity of the axial direction perpendicular the same, the arrangement angle is also the same 120 °, a regular It is arranged at the position. Crude arm Ab finishing out for material 5, the axial thickness (arm Ac of finish 6) arm portion A of the forged crankshaft final shape is the same.
[0038]
　In contrast, crude journal portion Ja of crude material 4 is rough journal portion Jb finishing out for material 5, that is, the axial length (journal Jc of finish 6) journal portion J of the forged crankshaft same it is. Crude pin portion Pa of the crude material 4, coarse pin portion Pb of the finishing out for material 5, that is, the axial length (pin portion Pc of the finish 6) the pin portion P of the forged crankshaft is the same, eccentricity amount is smaller than the coarse pin portion Pb of the strike for the material 5 finish. Specifically, of the crude pin portion Pa of the crude material 4, the first and third coarse pin portion P1a, eccentricity of P3a at both ends, eccentricity of the pin portion P of the forged crankshaft in directions opposite to each other is the same as that of √3 / 2. On the other hand, the amount of eccentricity of the second coarse pin portion P2a of central, the eccentricity of the first and third coarse pin portion P1a, the pin portion P of the forged crankshaft in a direction perpendicular to the direction of eccentricity of the P3a 1 / it is about 2.
[0039]
　Of coarse arm portion Aa of the crude material 4, Weighted coarse arm Aa (first, second, fifth and sixth coarse arm A1a, A2a, A5a, A6a) is, material for striking finish corresponding to each with 5 weight coarse arm Ab, that is, a thick axial thickness than Weighted arm a forged crankshaft (Weighted arm portion of the finish 6 Ac). On the other hand, oval crude material 4 coarse arm Aa (the third and fourth coarse arm portion A3a, A4a) is oval-shaped coarse arm Ab finishing out for material 5 corresponding to each, i.e. oval forged crankshaft form arm a (oval arm portion of the finish 6 Ac) and axial thickness are the same. In short, the coarse material 4, as compared to finish out the material for 5 (forged crankshaft and finish 6 final shape), long total length have thicker min thickness of Weighted coarse arm portion Aa, crude pin portion Pa eccentricity is small. Thus, the crude material 4 has a relatively gentle crankshaft shape.
[0040]
　However, strictly speaking, the material 5 for beating finish, with respect to forging the crank shaft and finish 6 final shape, is slightly thinner thickness of the coarse arm Ab, that much crude journal Jb and coarse pin portion Pb It is slightly greater axial length of the. Material 5 for beating finish during finish stamped easily accommodated in a mold, in order to prevent the occurrence of galling flaws. In response to this, the crude material 4 also, with respect to forging the crank shaft and finish 6 final shape, is slightly greater axial length of the coarse journal Ja and coarse pin portion Pa.
[0041]
　1-2. Manufacturing process of forging the crank shaft
　Figure 3 is a schematic diagram showing a manufacturing process of a forged crankshaft in the first embodiment. As shown in FIG. 3, method for manufacturing a forged crankshaft of the first embodiment, the first preformed second preforming, comprises the steps of finishing strike, if necessary, burrs punching, each step of shaping including.
[0042]
　First preforming step is a step of shaping the crude material 4 above. In the first preforming step, cross-section a round billet round a raw material, subjected to preliminary molding after heating the round billet by induction heating furnace or gas heating furnace. For example, the volume of the volume by rolling diaphragm the round billet by grooved rolls do roll forming to allocate longitudinally, thereby resulting roll wasteland partially pressing pressure from the longitudinal and perpendicular directions It repeated bending beating to allocate. Thus, it is possible to manufacture a crude material 4. Its Besides, even using the techniques disclosed in Patent Documents 1 and 2, shaping the crude material 4 is possible. It is also possible to employ cross-roll, a blockage such as forging.
[0043]
　Second preforming step is a step of forming the finishing beating material for 5 above. In the second preforming step, the process using a molding apparatus shown in Figure 4 below. Thus, the above crude material 4, the final shape of the forged crankshaft including an arrangement angle of the pin portion can be molded finish beating material for 5, which is shaped.
[0044]
　Finish beating step is a step of obtaining a finish 6 above. The finishing beating process, material for out finishing of the 5 is subjected to press-forging using a pair of dies vertically. Accordingly, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped, it is possible to obtain a finish 6 shaped to conform to the crankshaft.
[0045]
　1-3. Molding device of the material for the hit finishing
　Figure 4 is a longitudinal sectional view showing the structure of the molding apparatus in the first embodiment. 4 shows a molding apparatus in the case of producing the crankshaft of the three-cylinder -4 Like counterweight, i.e. illustrate molding apparatus for molding a material 5 for finishing out from the coarse material 4 shown in FIG. 2. Incidentally, in the longitudinal section shown in FIG. 4, portions of the first and third coarse pin section, in fact, one of the other located in front of the paper is positioned in the back, for convenience, the same surface It is shown in the figure above.
[0046]
　As shown in FIG. 4, the molding apparatus is obtained by utilizing a press having a lower hard plates 20 of the underlying fixed, the upper hard plate 21 to descend with the ram of the drive of the press. Directly above the lower hard plates 20, the lower die support base 22 is elastically supported via the elastic member 24. The lower mold support platform 22 is moved in the vertical direction is allowed. As the elastic members 24, disc springs, coil springs, it can be applied to air spring or the like, can be applied to hydraulic spring system to other. Directly below the upper hard plate 21, the upper mold support 23 is fixed through the supports 25. The upper die support 23 is lowered integrally with the upper hard plate 21 by the driving of the press (ram).
[0047]
　In the molding apparatus shown in Figure 4, the crude material 4, the first and third coarse pin unit P1a, a horizontally arranged P3a, in the mold in a position of arranging the second coarse pin portion P2a in a downward vertical direction accommodating to. Forming the crude material 4 in this position the material for out finish. Therefore, the lower mold support base 22 and the upper mold support 23 is divided along the axial direction of the crude material 4, the fixed journal type 9U, each forming a vertical against, 9B, the movable journal type 10 U, 10B, and the reference pin-type 11 and the auxiliary pin-type 13, and the movable pin die 12 and the auxiliary pin mold 13 is attached.
[0048]
　Reference pin mold 11 and the auxiliary pin-type 13 forming a vertically pair are arranged in a reference position of the second coarse pin portion P2a of the center of the coarse pin portion Pa in the coarse material 4, each upper and lower upper metal type support 23, attached to the lower die support base 22. Reference pin mold 11 of the first embodiment, the side where the normal position of the second coarse pin portion P2a are arranged on the opposite side. Other auxiliary pin die 13 is located outside of the side as the position of the normal of the second crude pin portion P2a. For example, in the position of the second coarse pin portion P2a, its normal position also under the arrangement of the second coarse pin portion P2a is a lower side. Therefore, the reference pin-type 11 with attached to the upper mold support 23, the auxiliary pin mold 13 is attached to the lower mold support base 22 forming a pair therewith.
[0049]
　In particular, the reference pin-type 11 and the auxiliary pin mold 13, both the upper and lower, on the upper mold support 23 and lower die support base 22, movement in the axial direction is restricted. The only reference pin mold 11, a direction perpendicular to the axial direction, the movement is allowed in the direction toward the normal position of the rough pin portion Pa (FIG. 4 in a downward direction).
[0050]
　Criteria pin-type 11 and the auxiliary pin die 13, respectively, semi-cylindrical engraved portions 11a, 13a are formed. Engraved portions 11a, the length of 13a is the same as the axial length of the second coarse pin portion P2b in the material 5 for beating finish.
[0051]
　Reference pin mold 11, lowering of the upper mold support 23 with the drive of the press, i.e. the pressure of the press, engraved portion 11a addressed to divide the second coarse pin portion P2a. At the same time, both sides of the reference pin-type 11, the third and fourth coarse arm portion A3a connected to the second rough pin portion P2a, contacts the side surface of the second coarse pin portion P2a side in A4a.
[0052]
　Movable pin die 12 and the auxiliary pin mold 13 which forms the upper and lower in pairs, the first and third coarse pin portion P1a, disposed P3a each position, each of the upper and lower upper mold support 23 and lower die support It is attached to the pedestal 22. Movable pin die 12 of the first embodiment, the side where the normal position of the rough pin portion Pa is arranged on the opposite side. Other auxiliary pin die 13 is located outside of the side as the normal position of the rough pin portion Pa. For example, at the position of the first coarse pin portion P1a, normal position of the first coarse pin portion P1a is upward. Therefore, the movable pin die 12 is attached to the lower die support base 22, the auxiliary pin mold 13 is attached to the upper mold support 23 forming a pair therewith.
[0053]
　In particular, the movable pin die 12 and the auxiliary pin mold 13, both the upper and lower, are moved on the lower mold support platform 22 and the upper mold support 23, in the axial direction toward the reference pin mold 11 acceptable It is. Only the movable pin die 12, a direction perpendicular to the axial direction, the movement is allowed in the direction toward the normal position of the rough pin portion Pa (FIG. 4 upward direction).
[0054]
　The movable pin die 12 and the auxiliary pin-type 13, respectively, semicylindrical engraved portions 12a, 13a are formed. Engraved portions 12a, the length of 13a is the same as the axial length of each coarse pin portion Pb of the material 5 for beating finish.
[0055]
　Fixed journaled 9U, 9B are oval in the crude material 4 coarse arm Aa (the third and fourth coarse arm portion A3a, A4a) crude journals Ja leading to (the second and third coarse journal portion J2a, J3A) disposed position, each vertically mounted on the upper mold support 23 and lower mold support platform 22. In particular, the fixed journal type 9U, 9B, both upper and lower, are completely fixed to the upper mold support 23 and lower die support base 22, movement in the axial direction is restricted.
[0056]
　Fixed journaled 9U, the 9B, respectively, the semi-cylindrical first engraved portion 9Ua, 9Ba and, the first engraved portion 9Ua, second engraved portions adjacent the front and rear (in FIG. 4, left and right) of 9Ba 9Ub, 9Bb and third engraved portion 9Uc, 9Bc are formed. First engraved portion 9Ua, length of 9Ba is rough journal portions of material 5 for beating finishing Jb (second and third coarse journal portion J2b, J3B) is the same as the axial length of the. Second engraved portion 9Ub, length of 9Bb is Weighted coarse arm portion leading to the crude journal portion Jb in material 5 for beating finishing Ab (the second and fifth coarse arm A2b, A5b) and the axial thickness of the it is the same. Third engraved portion 9Uc, length of 9Bc is oval coarse arm portion leading to the crude journal portion Jb in material 5 for beating finishing Ab (third and fourth coarse arm portion A3b, A4b) and the axial thickness of the it is the same.
[0057]
　Fixed journaled 9U, 9B, due pressure of the press, the first engraved portion 9Ua, held by sandwiching from above and below each crude journal portion Ja corresponding to each individually 9Ba. At the same time, the fixed journal type 9U, 9B, the second engraved portion 9Ub, 9Bb and third engraved portion 9Uc, first engraved portion 9Ua of 9bc, surface of 9Ba side, each crude journals Ja corresponding to each contacting the side of each crude journals Ja side of Weighted coarse arm portions Aa and oval coarse arm Aa lead.
[0058]
　Movable journaled 10 U, 10B are oval shaped in the crude material 4 coarse arm Aa (the third and fourth coarse arm portion A3a, A4a) crude journals Ja leading to (the second and third coarse journal portion J2a, J3A) other coarse journal portion Ja (first and fourth coarse journal portion J1a, J4A) is arranged at the position of each of the upper and lower is attached to the upper mold support 23 and lower mold support platform 22. In particular, the movable journal type 10 U, 10B, both the upper and lower, on the upper mold support 23 and lower die support base 22, movement is permitted in the axial direction toward the reference pins type 11.
[0059]
　Movable journaled 10 U, the 10B, respectively, the semi-cylindrical first engraved portion 10Ua, 10Ba and, the first engraved portion 10Ua, the second engraved portions adjacent the front and rear (in FIG. 4, left and right) of 10Ba 10UB, 10Bb are formed. First engraved portion 10Ua, the length of the 10Ba is rough journal portions of material 5 for beating finishing Jb (first and fourth coarse journal portion J1b, J4B) is the same as the axial length of the. Second engraved portion 10UB, the length of 10Bb are Weighted coarse arm portion leading to the crude journal portion Jb in material 5 for beating finishing Ab (first and sixth coarse arm A1b, A6b) and the axial thickness of the it is the same.
[0060]
　Movable journaled 10 U, 10B, due pressure of the press, the first engraved portion 10Ua, held by sandwiching from above and below each crude journal portion Ja corresponding to each individually 10Ba. At the same time, the movable journal type 10 U, 10B, the second engraved portion 10UB, first engraved part 10Ua of 10Bb, the surface of the 10Ba side, the Weighted coarse arm Aa connected to each coarse journals Ja corresponding to each contacting the side of each crude journal portion Ja side.
[0061]
　At that time, the reference pin-type 11 and the movable pin die 12, the pressure of the press, engraved portions 11a, 12a are addressed to cracking in the coarse pin portion Pa, both side surfaces of the reference pin die 11 and the movable pin mold 12, contacting the side of each coarse pin portion Pa side in the coarse arm Aa connected to each coarse pin portion Pa.
[0062]
　Here, the first and fourth coarse journal portion J1a, movable journaled disposed position of J4A 10 U across, 10B the end faces of the inclined surface 14U, and has a 14B. In contrast, on the lower hard plates 20, their first and fourth coarse journal portion J1a, movable journaled 10U of J4A, 10B of the inclined surface 14U, corresponding to the position of 14B, individually, wedge 26 is erected. Each wedge 26, projecting upwardly through the lower mold support base 22. The first and fourth coarse journal portion J1a, movable journaled 10U of J4A, among 10B, the inclined surface 14B of the lower side of the movable journal die 10B is in contact with the inclined surface of the wedge 26 in the initial state. On the other hand, the inclined surface 14U of the upper movable journaled 10U, due pressure of the press, in contact with the inclined surface of the wedge 26.
[0063]
　Then, along with the continuation of the pressure of the press, the upper movable journaled 10U is depressed by the movable journaled 10B integral with the lower side. Thus, the first and fourth coarse journal portion J1a, movable journaled 10U of J4A, 10B, both the upper and lower, since the inclined surfaces 14U, 14B slides along the inclined surface of the wedge 26, the reference and made to move in the axial direction toward the reference pin mold 11 of the second coarse pin portion P2a. In short, the movable journal type 10 U, 10B can be moved axially by the individual wedge mechanism.
[0064]
　Further, the movable pin die 12 and the auxiliary pin mold 13 is pushed down integrally with the continuation of the pressure of the press. Thus, the movable pin die 12 and the auxiliary pin die 13, the movable journaled 10U as described above, 10B is brought to move in the axial direction, the reference pin-type 11 of the second coarse pin portion P2a as a reference moves in the axial direction towards. Also, movement in the axial direction perpendicular to the direction of the reference pin die 11 and the movable pin mold 12 is performed by driving the hydraulic cylinder 16 connected to the pin-type 11 and 12.
[0065]
　Incidentally, the movement of the movable pin die 12 in the axial direction of the auxiliary pin-type 13, the movable journal type 10 U, or using the same wedge mechanism and 10B, by using a hydraulic cylinder, a separate mechanism such as a servo motor, force it may be carried out. Auxiliary pin die 13, a pair of adjacent movable journaled 10 U, one of 10B, or fixed journal type 9U, may be integrated with one of 9B.
[0066]
　In the initial state shown in FIG. 4, the movable journal type continuous individually axially 10 U, 10B and the fixed journal type 9U, and 9B, between the movable pin die 12 and the auxiliary pin-type 13, a gap is ensured. Movable journaled 10 U, 10B, as well as to permit axial movement of the movable pin die 12 and the auxiliary pin-type 13. The dimensions of each of these gaps is the difference between the thickness of the weight with the coarse arm Aa in the thickness and roughness material 4 Weighted coarse arm Ab in material 5 for beating finish.
[0067]
　Next, a description will be given such a configuration method of molding the material for out finishing by molding apparatus.
　5A and 5B are a longitudinal sectional view for explaining the method of molding the material for out finishing by molding device of the first embodiment shown in FIG. Of these figures, FIG. 5A shows a forming initial state, FIG. 5B shows a state during molding completed.
[0068]
　Movable journaled 10B of the lower side shown in FIG. 4, the fixed journal type 9B, houses the crude material 4 to the movable pin die 12 and the auxiliary pin-type 13, starts the reduction of the press. Then, first, as shown in FIG. 5A, the upper movable journaled 10U and the fixed journal type 9U, respectively, abut against the movable journal die 10B and a stationary journaled 9B lower.
[0069]
　Thus, the coarse material 4, each coarse journal portion Ja is movable journaled 10 U, 10B and the fixed journaled 9U, held from above and below by 9B, destined reference pin die 11 and the movable pin die 12 within each coarse pin portion Pa in a state where the crack was. In this state, the side surface of the rough journal portion Ja side of each coarse arm portions Aa of crude material 4, the movable journal type 10 U, 10B and the fixed journal type 9U, 9B contacts, crude pins in each coarse arm portions Aa the side parts Pa side, the reference pin-type 11 and the movable pin die 12 are in contact. Further, in this state, the first and fourth coarse journal portion J1a, movable journaled 10U of J4A, 10B of the inclined surfaces 14U, 14B are in contact with the inclined surface of the wedge 26.
[0070]
　From this state, to continue the pressure of the press as it is. Then, the first and fourth coarse journal portion J1a, movable journaled 10U of J4A, 10B, each of the inclined surfaces 14U, 14B slides along the inclined surface of the wedge 26, the wedge mechanism, a second coarse pins moves in the axial direction toward the reference pin type 11 parts P2a. Thus the movable journal type 10 U, 10B along with the movement by the wedge mechanism axially individually movable pin die 12 and the auxiliary pin die 13 is also moved in the axial direction toward the reference pin type 11.
[0071]
　Thus, the movable journal type 10 U, 10B and the fixed journal type 9U, 9B, narrowed gradually the gap between the movable pin die 12 and the auxiliary pin-type 13, each of which gaps is eliminated in the final. At that time, crude material 4, the movable journal type 10 U, 10B, the fixed journal type 9U, 9B, the reference pin-type 11 and the movable pin die 12, the axial length of the coarse journal Ja and coarse pin portion Pa is maintained while being, Weighted coarse arm portion Aa is clamped in the axial direction. Then, reduced to a thickness of the weight with the coarse arm Ab threshing material for 5 finish the thickness of the Weighted coarse arm Aa (see FIG. 5B).
[0072]
　The movable journaled 10 U, 10B, and depending on the axial movement of the movable pin die 12 and the auxiliary pin die 13, to drive the reference pin die 11 and the movable pin die 12 each hydraulic cylinder 16. Then, each pin-type 11 and 12, individually, to press the rough pin portion Pa of the crude material 4 in the axial direction and perpendicular. Thus, the coarse pin portion Pa of the crude material 4, since the axially offset and perpendicular vertical direction, increases to eccentricity of crude pin portion Pb of the strike for the material 5 that eccentricity is finishing, either crude pin portion Pb is also a state of being arranged in the normal position (see FIGS. 2 and 5B).
[0073]
　In this manner, the no burrs crude material 4, generally in matching shape as the Weighted arm A at a thickness of the arm portion A be a thin three-cylinder engine forged crankshaft (final forged product), it is possible to mold the material 5 for finishing out with no burrs. Then, by performing such was subjected to finish out a material 5 without burrs finish beating by finishing beating, although some burrs occur, three-cylinder engine including an arrangement angle of the contour shape and the pin portion of the arm portion the final shape of use forged crankshaft can be shaped. Therefore, good yield forged crankshaft for 3-cylinder engine, moreover, it is possible to manufacture with high dimensional accuracy regardless of its shape.
[0074]
　FIG 4, in the molding apparatus shown in FIGS. 5A and 5B, movable journaled 10U of the first coarse journal portion J1a, 10B of the inclined surface 14U, and the slope of the wedge 26 to 14B and in contact with this, the fourth coarse journals movable journaled 10U of J4A, 10B of the inclined surface 14U, and 14B and the inclined surface of the wedge 26 in contact with this, the inclination angle is an opposite relative to the vertical plane. The reason for varying the wedge angle of the wedge mechanism for moving the movable journaled 10 U, and 10B in the axial direction movable journaled 10 U, per. 10B, thickness nipped the Weighted crude arm portion Aa axially This is to constant for all weights with coarse arm Aa a deformation rate to reduce.
[0075]
　FIG 4, crude material 4 used in the molding apparatus shown in FIGS. 5A and 5B, the cross-sectional area of ​​the coarse journal portion Ja is finishing out for material 5 of the coarse journal portion Jb, i.e. interruption of the journal portion J of the forged crankshaft or is the same as the area is larger than that. Similarly, the cross-sectional area of ​​the coarse pin portion Pa of the crude material 4, coarse pin portion Pb of the finishing out material for 5, i.e. whether it is the same as the cross-sectional area of ​​the pin portion P of the forged crankshaft, larger than that. Even if the cross-sectional area of ​​the coarse journal portion Ja of crude material 4 is larger than the cross-sectional area of ​​the coarse journal portion Jb threshing material for 5 finish, rough journal threshing material for 5 finish the cross-sectional area of ​​the coarse journal portion Ja until the cross-sectional area of ​​the part Jb can be reduced. This movable journaled 10U, 10B of the crude journal portion Ja pinching hold, and the movable journaled 10U following this, by movement in the axial direction of 10B. Further, even if the cross-sectional area of ​​the coarse pin portion Pa of the crude material 4 is larger than the cross-sectional area of ​​the coarse pin portion Pb of the strike for the material 5 finish, coarse pin portion the cross-sectional area finishing out for material 5 Pa until the cross-sectional area of ​​the coarse pin portion Pb can be reduced. This is in addition to the movement in the axial direction perpendicular to the direction of the reference pin type 11, due to movement of the mobile and this direction perpendicular to the axial direction of the movable pin die 12.
[0076]
　Above It should be noted the described finish out molding material, there is occurrence of localized chewing out against Weighted coarse arm portion Aa. The following is a description generation principle of out chewing and their countermeasures.
[0077]
　Figure 6 is a diagram for explaining a situation that out chewy molding material for out finishing by molding device occurs, FIG. 7 is a diagram for explaining a situation when subjected to the countermeasure . In FIG. 6 and FIG. 7, (a) shows the state of forming the initial, the (b) is in the middle of molding conditions, (c) a state during molding completed, (d) was taken out from the molding apparatus after completion molding shows the material for the hit finish, respectively.
[0078]
　As shown in FIG. 6 (a), when the molding is started, the movable journal type 10 U, with 10B is moved in the axial direction, the movable pin die 12 and the auxiliary pin-type 13 in the axial direction and this direction perpendicular Moving. Thereafter, as shown in FIG. 6 (b), in Weighted coarse arm Aa, the movable journal type 10 U, 10B, and before axial movement of the movable pin die 12 and the auxiliary pin mold 13 is completed, i.e. , movable journaled 10 U, 10B and the fixed journal type 9U, and 9B, before the gap between the movable pin die 12 and the auxiliary pin mold 13 is closed, crude pin portion Pa for pressing deformed axially perpendicular direction auxiliary Upon reaching the pin mold 13, it occurs a situation described below. Auxiliary pin die 13 and the movable journal type 10 U, 10B and the fixed journal type 9U, the gap between 9B, meat coarse pin portion Pa flows. The inflow meat, although gradually extended thinly with the progress of molding, as shown in FIG. 6 (c), also remain in the molding complete. Thus, as shown in FIG. 6 (d), on the outside of the coarse pin portion Pb of the finishing out material for 5, local chewing out section 5a at the boundary between the Weighted coarse arm Aa adjacent appears.
[0079]
　Chewing out section 5a is a head flaws driven into the product on a finish beating the next step. Therefore, in order to ensure the product quality, it is necessary to prevent the occurrence of out chewing.
[0080]
　The countermeasures to prevent the occurrence of out chewing, the Weighted coarse arm Aa, the movable journal type 10 U, 10B and the fixed journal type 9U, and 9B, a gap between the movable pin die 12 and the auxiliary pin mold 13 is closed after the crude pin portion Pa for pressing deformation so as to reach the auxiliary pin mold 13 may be controlled to move in the axial direction perpendicular to the direction of movable pin die 12. Specifically, the movable journal type 10 U, 10B, and after the axial movement of the auxiliary pin-type 13 which forms a movable pin die 12 and the movable pin die 12 and the counter has been completed, the axial direction of the movable pin type 12 it is sufficient to complete the movement in the perpendicular direction. For example, when the total distance in the axial direction perpendicular to the direction of movable pin die 12 and 100%, when the movable journal type 10 U, the axial movement of the 10B was completed adjacent to the movable pin die 12 , the moving distance in the axial direction perpendicular to the direction of the movable pin die 12 is less than 90% of the total distance traveled (more preferably 83% or less, more preferably 60% or less) is preferably. Move in that direction of the movable pin die 12 may be completed after this.
[0081]
　For example, as shown in FIG. 7 (a), it starts forming. Thereafter, as shown in FIG. 7 (b), in the Weighted coarse arm portion Aa, until the moving distance in the axial direction perpendicular to the direction of the movable pin die 12 reaches 90% of the total distance traveled, the movable journal type 10 U, 10B, and to complete the movement in the axial direction of the movable pin die 12 and the auxiliary pin-type 13. Then, at this time, the movable journal type 10 U, 10B and the fixed journal type 9U, 9B and, although the gap between the movable pin die 12 and the auxiliary pin mold 13 is closed, the coarse pin portion Pa that presses deformable auxiliary pins It does not reach the mold 13. When the rough pin portion Pa with the movement in the axial direction perpendicular to the direction of the movable pin die 12 reaches the auxiliary pin-type 13, the movement is completed, as shown in FIG. 7 (c), molding completed. Therefore, the auxiliary pin-type 13 and the movable journal type 10 U, 10B and the fixed journal type 9U, the gap between 9B, situation in which the meat of the coarse pin portion Pa flows does not occur. Thus, as shown in FIG. 7 (d), it is possible to obtain a material 5 for beating finishing without chewing out high quality.
[0082]
　Moving process of the movable pin type axial direction perpendicular to the axial movement of the movable journal type is completed, can be arbitrarily changed. For example, the movement in the axial direction perpendicular to the direction of movable pin type, may be started simultaneously with the start of movement in the axial direction of the movable journal type, it may be started before it or movable journal movement of the mold in the axial direction of the may start after certain extent. Also, movement in the axial direction perpendicular to the direction of movable pin type, after the start, temporarily stopped at a position a certain amount of movement, may be resumed after the movement in the axial direction of the movable journal type has been completed.
[0083]
　2. Second Embodiment
　The second embodiment is basically the structure of the first embodiment described above. The second embodiment, with the addition of torsional molding step to the production process of forged crankshaft, is a modification of the structure related thereto.
[0084]
　2-1. Crude material, finishing out for material, finish, and torsional finish
　8 is the manufacturing method of the second embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, after the finish beating finish, and is a diagram schematically illustrating a shape of the torsion finish after twisting molding. 8, similarly to FIG. 2, showing the situation in the case of producing the crankshaft of the three-cylinder -4 Like counterweight. Incidentally, omitted in order to avoid redundancy and the first embodiment as appropriate. The same applies to the third and fourth embodiments described below.
[0085]
　As shown in FIG. 8, the crude material 4 of the second embodiment is rough crankshaft shape as a whole, while relying on the shape of the forged crankshaft 1 of 3 cylinders -4 Like counterweight. The crude material 4, four crude journals Ja, 3 single coarse pin portions Pa, crude front portion Fra, crude flange FIa, and consists of six crude arm portion Aa. The finishing out for material 5 of the second embodiment, the above crude material 4, details of which are molded by a molding device to be described later. Finishing out material for 5, four crude journals Jb, 3 single coarse pin portions Pb, crude front portion Frb, crude flange FLB, and consists of six crude arm Ab. Finish 6 of the second embodiment is obtained by beating finishing materials 5 for beating finishing above. Finish 6 has four journals Jc, 3 one pin portion Pc, a front portion Frc, flange Flc, and consists of six arm portions Ac.
[0086]
　Twisting finish 7 of the second embodiment is obtained by the above the finish 6 and torsion molding. Twisting finish 7, four journal portions J1d ~ J4d, 3 one pin portions P1d ~ P3d, the front portion Frd, flange Fld, and six crank arm connecting the journal portion J1d ~ J4d a pin portion P1d ~ P3d respectively section (hereinafter, simply referred to as "arm portion") consists of A1d ~ A6d. Hereinafter, the journal portion J1d ~ J4d torsional finish 7, the pin unit P1d ~ P3d, and will be collectively each arm portion A1d ~ A6d, the sign, in the journal portion "Jd", "Pd" in the pin, the arm It referred to as "Ad" in parts.
[0087]
　The shape of the torsion finish 7 is consistent with the shape of the crankshaft (final forged product), including the placement angle of the pin portion Pd. That is, the journal portion Jd torsion finish 7, the journal portion J and the axial length of the forged crankshaft final shape is the same. Pin portion Pd of the torsion finish 7, pin length P and the axial direction of the forged crankshaft final shape is the same. Further, the pin portion Pd of the torsion finish 7, compared pin portion P of the forged crankshaft final shape, a eccentricity of the axial direction perpendicular the same, the arrangement angle is also the same 120 °, a regular It is disposed at a position. Arm Ad torsion finish 7, the arm portion A and the axial thickness of the forged crankshaft final shape is the same.
[0088]
　The shape of finish 6 is consistent with the shape of the crankshaft (final forged product) except placement angle of the pin portion Pc. That is, the journal portion Jc of finish 6, the journal portion J and the axial length of the forged crankshaft final shape is the same. Pin portion Pc of the finish 6, the pin portion length P and the axial direction of the forged crankshaft final shape are the same, eccentricity of the axial perpendicular direction is the same. However, the arrangement angle of the pin portion Pc of the finish 6 is out of the normal position. Specifically, of the pin portion Pc of the finish 6, the first and third pin portion P1c at both ends, P3c are eccentric in the same direction in the axial direction perpendicular to the direction. The second pin portion P2c of central, first and third pin portion P1c, and the direction of eccentricity of P3c are eccentric in opposite directions. Arm of the finish 6 Ac is the arm portion A and the axial thickness of the forged crankshaft final shape is the same.
[0089]
　The shape of the finishing out for material 5 is generally consistent with the shape of the finish 6. That is, the coarse journal portion Jb finishing out for material 5, the axial length (journal Jc of finish 6) journal portion J of the forged crankshaft final shape is the same. Crude pin portion Pb of the finishing out material for 5, to the pin portion P of the forged crankshaft final shape (pin portion Pc of the finish 6), a length in the axial direction is the same, the axial direction perpendicular of but eccentricity is the same, is out of Likewise the normal position and its placement angle finish 6. Crude arm Ab finishing out for material 5, the axial thickness (arm Ac of finish 6) arm portion A of the forged crankshaft final shape is the same.
[0090]
　In contrast, crude journal portion Ja of crude material 4 is rough journal portion Jb finishing out for material 5, that is, the axial length (journal Jc of finish 6) journal portion J of the forged crankshaft same it is. Crude pin portion Pa of the crude material 4, coarse pin portion Pb of the finishing out for material 5, that is, the axial length (pin portion Pc of the finish 6) the pin portion P of the forged crankshaft is the same, eccentricity amount is smaller than the coarse pin portion Pb of the strike for the material 5 finish. Specifically, of the crude pin portion Pa of the crude material 4, the first and third coarse pin portion P1a ends, eccentricity of P3a is the eccentricity of the pin portion P in the same direction forged crankshaft it is about 1/2. On the other hand, the amount of eccentricity of the center of the second coarse pin portion P2a, the first and third coarse pin portion P1a, the eccentricity of the pin portion P of the forged crankshaft in a direction opposite to the direction of eccentricity of the P3a 1/2 it is the degree.
[0091]
　Of coarse arm portion Aa of the crude material 4, Weighted coarse arm Aa (first, second, fifth and sixth coarse arm A1a, A2a, A5a, A6a) is, material for striking finish corresponding to each with 5 weight coarse arm Ab, that is, a thick axial thickness than Weighted arm a forged crankshaft (Weighted arm portion of the finish 6 Ac). On the other hand, oval crude material 4 coarse arm Aa (the third and fourth coarse arm portion A3a, A4a) is oval-shaped coarse arm Ab finishing out for material 5 corresponding to each, i.e. oval forged crankshaft form arm a (oval arm portion of the finish 6 Ac) and axial thickness are the same.
[0092]
　2-2. Manufacturing process of forging the crank shaft
　9 are schematic views showing a manufacturing process of forging the crank shaft in the second embodiment. As shown in FIG. 9, the manufacturing method of forging the crank shaft of the second embodiment, the first preformed second preformed, finish out, it comprises the steps of twisting molding, optionally, prior to twisting shaping Bali opener, comprising the steps of shaping after twisting molding.
[0093]
　First preforming step is a step of shaping the crude material 4 above. Second preforming step, by using a molding apparatus shown in Figure 10 below, the above from the crude material 4, except for the arrangement angle of the pin portion forged crankshaft final shape is material for finishing beating defined above which is shaped 5 is a step of forming a. Finish beating process, material 5 for beating finishing the above is provided, the final shape of the forged crankshaft except placement angle of the pin portion is a step of obtaining a finish 6 above that have been shaped.
[0094]
　Twisting forming step is a step of obtaining the above-mentioned torsion finish 7. The twisting molding process, twisted around the axial center of the journal portion while holding the journal portion and the pin portion of the finishing material 6. Thus, by adjusting the arrangement angle of the pin portion on the arrangement angle of the pin portion of the forged crankshaft, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped, twisting finish shape that matches the crankshaft 7 can be obtained.
[0095]
　2-3. Finish out molding device of the material
　Figure 10 is a longitudinal sectional view showing the structure of the molding apparatus in the second embodiment. Figure 10 illustrates a molding apparatus for molding a material 5 for striking finish from a crude material 4 shown in FIG. 8. The longitudinal section shown in FIG. 10, actually part of all crude pin portion is included on the same plane.
[0096]
　In the molding apparatus of the second embodiment shown in FIG. 10, the crude material 4 is accommodated in the mold direction of eccentricity of the crude pin portion Pa in the combined position in the vertical direction. For example, the crude material 4, the first and third coarse pin portion P1a, arranged above the P3a, and posture of the second coarse pin portion P2a was placed under. Forming the crude material 4 in this posture out for the material 5 finish. Configuration other than this point, because in common with the molding device of the first embodiment shown in FIG. 4, a detailed description thereof will be omitted.
[0097]
　11A and 11B are a longitudinal sectional view for explaining a method of molding the material for out finishing by molding device of the second embodiment shown in FIG. 10. Of these figures, FIG. 11A shows the molding initial state, FIG. 11B shows a state during molding completed.
[0098]
　As shown in FIG. 11A, the lower side of the movable journaled 10B, fixed journaled 9B, houses the crude material 4 to the movable pin die 12 and the auxiliary pin-type 13 to pressure of the press. Then, the crude journal portions Ja movable journaled holding the 10 U, 10B is moved in the axial direction toward the reference pin type 11 destined is cracking the second coarse pin portion P2a, along with this, the first and third coarse pin portion P1a, the movable pin die 12 and the auxiliary pin-type 13 destined has We also P3a, moves in the axial direction toward the reference pin type 11. Thus, the coarse material 4, the movable journal type 10 U, 10B, the fixed journal type 9U, 9B, the reference pin-type 11 and the movable pin die 12, the axial length of the coarse journal Ja and coarse pin portion Pa maintained while being, Weighted coarse arm portion Aa is clamped in the axial direction. Then, reduced to a thickness of the weight with the coarse arm Ab threshing material for 5 finish the thickness of the Weighted coarse arm Aa (see FIG. 11B).
[0099]
　Further, according to the movement of the movable journal type 10 U, 10B, and the axial direction of the movable pin die 12 and the auxiliary pin-type 13, the reference pin-type 11 and the movable pin die 12, with the drive of the respective hydraulic cylinders 16, each in, presses the rough pin portion Pa of the crude material 4 in the axial direction and perpendicular. Thus, the coarse pin portion Pa of the crude material 4, since the axially offset and perpendicular, while the arrangement angle is not deviated from the regular position, the coarse pin portion of the strike for the material 5 that eccentricity is finish the increased until eccentricity amount of pb (see FIGS. 8 and 11B).
[0100]
　In this manner, the no burrs crude material 4, pin 3-cylinder engine forged crankshaft except placement angle P shape roughly matching the shape of the (final forged product), material for striking finish no burrs 5 it can be molded. Then, by performing the finish beating subjecting the material 5 for beating finishing without such burrs finish beating, some burr occurs but the final shape of the three-cylinder engine forged crankshaft except placement angle of the pin portion There can be obtained a finish 6 which are shaped. Then, if Hodokose molding twisting to the finish 6, it is possible to manufacture a final shape of the forged crankshaft for 3-cylinder engine, including an arrangement angle of the pin portion. Therefore, good yield forged crankshaft for 3-cylinder engine, moreover, it is possible to manufacture with high dimensional accuracy regardless of its shape.
[0101]
　3. Third Embodiment
　The third embodiment is a basic configuration of the first and second embodiments described above. The third embodiment, without adding a forming process torsion production process of forged crankshaft, intended to shape the final shape of the crankshaft in the finishing beating process, is a modification of the structure related thereto .
[0102]
　3-1. Crude material, for out finishing material, and finish
　12 is the manufacturing method of the third embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and the finishing beating after the finish each shape of a diagram schematically showing. FIG 12, similarly to FIG. 2 and FIG. 8 illustrates a situation in the case of producing the crankshaft of the three-cylinder -4 Like counterweight.
[0103]
　As shown in FIG. 12, the coarse material 4 of the third embodiment is rough crankshaft shape as a whole, while relying on the shape of the forged crankshaft 1 of 3 cylinders -4 Like counterweight. The crude material 4, four crude journals Ja, 3 single coarse pin portions Pa, crude front portion Fra, crude flange FIa, and consists of six crude arm portion Aa. The finishing out for material 5 of the third embodiment, the above crude material 4, details of which are molded by a molding device to be described later. Finishing out material for 5, four crude journals Jb, 3 single coarse pin portions Pb, crude front portion Frb, crude flange FLB, and consists of six crude arm Ab. Finish 6 of the third embodiment is obtained by beating finishing materials 5 for beating finishing above. Finish 6 has four journals Jc, 3 one pin portion Pc, a front portion Frc, flange Flc, and consists of six arm portions Ac.
[0104]
　The shape of finish 6 is consistent with the shape of the crankshaft (final forged product), including the placement angle of the pin portion Pc. That is, the journal portion Jc of finish 6, the journal portion J and the axial length of the forged crankshaft final shape is the same. Pin portion Pc of the finish 6, the pin portion length P and the axial direction of the forged crankshaft final shape is the same. Further, the pin portion Pc of the finish 6, compared pin portion P of the forged crankshaft final shape, a eccentricity of the axial direction perpendicular the same, the arrangement angle is also the same 120 °, the normal position It is located in. Arm of the finish 6 Ac is the arm portion A and the axial thickness of the forged crankshaft final shape is the same.
[0105]
　In contrast, crude journal portion Jb finishing out for material 5, the journal portion Jc of finish 6, that is, the journal portion J and the axial length of the forged crankshaft is the same. Crude pin portion Pb of the finishing out for material 5, the pin portion Pc of the finish 6, i.e. the pin portion length P and the axial direction of the forged crankshaft have the same eccentricity amount arrangement angles the normal position It is out from. Specifically, of the crude pin portion Pb of the finishing out for material 5, the first and third coarse pin portion P1b both ends, eccentricity of P3b are polarization of the pin portion P of the forged crankshaft in directions opposite to each other is the same as the √3 / 2 of the core amount. On the other hand, the second coarse pin portion P2b of the central without being eccentric, the eccentricity amount is zero. Crude arm Ab finishing out for material 5, the axial thickness (arm Ac of finish 6) arm portion A of the forged crankshaft final shape is the same.
[0106]
　Further, crude journal Ja of crude material 4 is a rough journal portion Jb finishing out for material 5, that is, the axial length (journal Jc of finish 6) journal portion J of the forged crankshaft same . Crude pin portion Pa of the crude material 4, coarse pin portion Pb of the finishing out for material 5, that is, the axial length (pin portion Pc of the finish 6) the pin portion P of the forged crankshaft is the same. However, among the rough pin portion Pa of the crude material 4, the first and third coarse pin portion P1a, eccentricity of P3a is smaller than that of the finishing out for material 5, pin forged crankshaft in directions opposite to each other less than √3 / 2 of the eccentricity of the parts P. On the other hand, the amount of eccentricity of the second coarse pin portion P2a is similar to the finishing out for material 5, is zero.
[0107]
　Of coarse arm portion Aa of the crude material 4, Weighted coarse arm Aa (first, second, fifth and sixth coarse arm A1a, A2a, A5a, A6a) is, material for striking finish corresponding to each with 5 weight coarse arm Ab, that is, a thick axial thickness than Weighted arm a forged crankshaft (Weighted arm portion of the finish 6 Ac). On the other hand, oval crude material 4 coarse arm Aa (the third and fourth coarse arm portion A3a, A4a) is oval-shaped coarse arm Ab finishing out for material 5 corresponding to each, i.e. oval forged crankshaft form arm a (oval arm portion of the finish 6 Ac) and axial thickness are the same.
[0108]
　3-2. Manufacturing process of forging the crank shaft
　13 is a schematic diagram showing a manufacturing process of a forged crankshaft in the third embodiment. As shown in FIG. 13, the production method of the forged crankshaft of the third embodiment, the first preformed second preforming, comprises the steps of finishing strike, if necessary, burrs punching, each step of shaping including.
[0109]
　First preforming step is a step of shaping the crude material 4 above. Second preforming step, by using a molding apparatus shown in Figure 14 below, the above crude material 4, the final shape of the forged crankshaft except eccentricity and arrangement angles of all of the pin portion is shaped a step of molding the finish beating material for 5 above.
[0110]
　Finish beating step is a step of obtaining a finish 6 above. The finishing beating process, material 5 for beating finishing the above is provided, in a state of orientation in which place the first and third coarse pin horizontally, pressed forging using a pair of dies vertically, all the crude pin portion is pressed in the axial direction perpendicular to the vertical direction. Accordingly, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped, it is possible to obtain a finish 6 shaped to conform to the crankshaft.
[0111]
　3-3. Molding device of the material for the striking finish
　14 is a longitudinal sectional view showing the structure of the molding apparatus in the third embodiment. Figure 14 illustrates a molding apparatus for molding a material 5 for striking finish from a crude material 4 shown in FIG. 12. The longitudinal section shown in FIG. 14, actually part of all crude pin portion is included on the same plane.
[0112]
　Molding apparatus of the third embodiment shown in FIG. 14, as compared to the molding device of the second embodiment shown the molding apparatus and FIG. 10 of the first embodiment shown in FIG. 4, large differences in the following points to. The molding apparatus of the third embodiment, the crude material 4 is accommodated in the mold in a posture in which disposed first and third coarse pin portion P1a and eccentric in opposite directions, the P3a along the vertical direction. Forming the crude material 4 in this posture out for the material 5 finish. At that time, the reference pin-type 11 disposed at the position of the second coarse pin portion P2a not only movement in the axial direction, is also constrained movement in the direction perpendicular to the axial direction. Therefore, the reference pin mold 11 of the third embodiment, one of the first and the hydraulic cylinder is not connected as in the second embodiment, the upper mold support 23 and lower mold support platform 22 on the other hand to be directly mounted. The other of the auxiliary pin-type 13 forming the reference pin mold 11 pair is directly attached. In Figure 14, the reference pin-type 11 is attached to the upper die support 23, showing an aspect auxiliary pin die 13 is attached to the lower mold support base 22.
[0113]
　Further, in the molding apparatus of the third embodiment, the first and third coarse pin portion P1a, the movable pin die 12 and the auxiliary pin mold 13 disposed P3a of each position, a position of the first coarse pin portion P1a first 3 the arrangement of the up and down position of the rough pin portion P3a are interchanged. The first and third coarse pin portion P1a, because P3a are eccentric in opposite directions in the vertical direction. In Figure 14, the auxiliary pin-type 13 position of the first coarse pin portion P1a, and the third movable pin die 12 in the position of the coarse pin portion P3a is disposed on the upper side, the movable pin type position of the first coarse pin portion P1a 12, and shows a third embodiment in which the auxiliary pin-type 13 position of the coarse pin portion P3a is disposed on the lower side.
[0114]
　15A and 15B are a longitudinal sectional view for explaining a third method of molding the material for out finishing by molding apparatus of the embodiment shown in FIG. 14. Of these figures, FIG. 15A shows the molding initial state, FIG. 15B shows a state during molding completed.
[0115]
　As shown in FIG. 15A, the lower side of the movable journaled 10B, fixed journaled 9B, houses the crude material 4 to the movable pin die 12 and the auxiliary pin-type 13 to pressure of the press. Then, firstly, the crude material 4, each coarse journal portion Ja is movable journaled 10 U, 10B and the fixed journal type 9U, at the same time is held sandwiched from above and below by 9B, second coarse pin portion P2a reference pin type 11 and is held sandwiched from above and below by auxiliary pin die 13, a state where the first and third coarse pin portion P1a, movable pin die 12 in P3a is destined Broken. From this state, when the continued reduction of the press, each coarse journal portions Ja movable journaled holding the 10 U, 10B is moved in the axial direction toward the reference pin mold 11 which holds the second coarse pin portion P2a, accordingly, the first and third coarse pin portion P1a, the movable pin die 12 and the auxiliary pin-type 13 destined has We also P3a, moves in the axial direction toward the reference pin type 11. Thus, the coarse material 4, the movable journal type 10 U, 10B, the fixed journal type 9U, 9B, the reference pin-type 11 and the movable pin die 12, the axial length of the coarse journal Ja and coarse pin portion Pa maintained while being, Weighted coarse arm portion Aa is clamped in the axial direction. Then, reduced to a thickness of the weight with the coarse arm Ab threshing material for 5 finish the thickness of the Weighted coarse arm Aa (see FIG. 15B).
[0116]
　Further, according to the movement of the movable journal type 10 U, 10B, and the axial direction of the movable pin die 12 and the auxiliary pin mold 13, the movable pin die 12, with the drive of the respective hydraulic cylinders 16, individually, the crude material 4 the first and third coarse pin portion P1a of pressing the P3a axially perpendicular vertical. Thus, the crude material 4 the first and third coarse pin portion P1a, P3a, since axially offset and perpendicular vertical direction, in the opposite direction of the eccentricity of the pin portion P of the forged crankshaft together √3 / the increased state to the same eccentricity as 2 (FIG. 12, see FIG. 15B). On the other hand, the second coarse pin portion P2a of the crude material 4, before and after the molding, its axial kept unchanged is perpendicular position, and remains eccentricity amount is zero.
[0117]
　In this manner, the no burrs crude material 4 in the form roughly matched the shape of all of the pin portion eccentricity and arrangement angles except 3-cylinder engine forged crankshaft P (final forged product), Bali it is possible to mold the material 5 for finishing out no. Then, subjecting the material 5 for beating finishing without such burrs finish beating, performing finish beating the first and third coarse pin portion in a state of horizontally arranged posture. At this time, by pressing all the crude pin for striking finishing material 5 in the axial direction perpendicular vertical direction, if to displace to the position of normal, although some burrs occur, the contour of the arm portion shape, including eccentricity and arrangement angle of the pin portion can be shaped the final shape of the forged crankshaft for 3-cylinder engine. Therefore, good yield forged crankshaft for 3-cylinder engine, moreover, it is possible to manufacture with high dimensional accuracy regardless of its shape.
[0118]
　4. Fourth Embodiment
　The fourth embodiment is a modification of the configuration of the third embodiment described above.
[0119]
　4-1. Crude material, finishing out for materials and finish,
　Figure 16 is the manufacturing method of the fourth embodiment, the coarse material to be object to be molded in the molding apparatus, the molded finish out a material, and the finishing beating after the finish each shape of a diagram schematically showing.
[0120]
　As shown in FIG. 16, finish 6 of the fourth embodiment is the same shape as the finish 6 of the third embodiment shown in FIG. 12.
[0121]
　In contrast, the finishing out for material 5 of the fourth embodiment, compared with the finishing out for material 5 of the third embodiment shown in FIG. 12, the following points are different. As shown in FIG. 16, the second coarse pin portion P2b of the center of the finishing out for material 5 of the fourth embodiment, the first and third coarse pin portion P1b at both ends, in a direction perpendicular to the direction of eccentricity of the P3b eccentric pin portion Pc of the eccentricity amount is finish 6, i.e. the same as the pin portion P of the forged crankshaft.
[0122]
　The crude material 4 of the fourth embodiment, as compared to the crude material 4 of the third embodiment shown in FIG. 12, the following points are different. As shown in FIG. 16, the second coarse pin portion P2a of the center in the coarse material 4 of the fourth embodiment, the first and third coarse pin portion P1a at both ends, eccentricity in the direction perpendicular to the direction of eccentricity of the P3a and its eccentricity is, similarly to that of the finishing out for material 5, the same as the pin portion P of the forged crankshaft (pin portion Pc of the finish 6).
[0123]
　4-2. Manufacturing process of forging the crank shaft
　17 are schematic views showing a manufacturing process of forging the crank shaft in the fourth embodiment. As shown in FIG. 17, the production method of the forged crankshaft of the fourth embodiment, like the third embodiment shown in FIG. 13, comprises a first preformed second preforming, the steps of finishing beating , if necessary, including the Bali opener, each step of the shaping.
[0124]
　First preforming step is a step of shaping the crude material 4 above.
[0125]
　Second preforming step is a step of forming the finishing beating material for 5 above. In the second preforming step, the 14, used the same as the molding apparatus of the third embodiment shown in FIGS. 15A and 15B. In the fourth embodiment, in a longitudinal section shown in FIG. 14, the portion of the second coarse pin portion is actually positioned in the plane of the front or rear.
[0126]
　In the second preforming step of the fourth embodiment, FIG. 14, similarly to the third embodiment shown in FIGS. 15A and 15B, below the journal type 10B, the fixed journal type 9B, the movable pin die 12 and the auxiliary pins the crude material 4 is accommodated in the mold 13, and the reduction of the pressing machine. Thus, each coarse journal portions movable journaled holding the Ja 10 U, 10B, and the first and third coarse pin unit P1a, a movable pin type 12 destined is cracked P3a auxiliary pin mold 13, a second coarse pins moves in the axial direction toward the reference pin mold 11 holding the part P2a. Accordingly, the coarse material 4, the axial length of the coarse journal Ja and coarse pin portion Pa is while being maintained, Weighted coarse arm portion Aa is clamped in the axial direction. Then, reduced to a thickness of the weight with the coarse arm Ab threshing material for 5 finish the thickness of the Weighted coarse arm portion Aa.
[0127]
　Further, the movable pin die 12 has first and third coarse pin unit P1a, presses the P3a axially perpendicular vertical. Thus, the first and third coarse pin portion P1a of crude material 4, P3a is a state of being increased to the same eccentricity as √3 / 2 of the eccentricity of the pin portion P of the forged crankshaft in directions opposite to each other Become. On the other hand, the second coarse pin portion P2a of the crude material 4, before and after the molding, its axial kept unchanged is perpendicular position, eccentricity of the pin portion of the eccentricity is forged crankshaft the same remains in the state with.
[0128]
　In this way, from the crude material 4 without burrs, roughly consistent with the shape of the first and third pin portions P1, P3 eccentricity and arrangement angles except 3-cylinder engine forged crankshaft (final forged product) shape can be molded materials 5 for beating finishing burr-free above.
[0129]
　Finish beating step is a step of obtaining a finish 6 above. The finishing beating process, material 5 for beating finishing the above is provided, performing finish beating the first and third coarse pin portion in a state of horizontally arranged posture. At this time, the first and threshing material for 5 finishing third coarse pin portion P1b, and pressed in the axial direction perpendicular vertical direction P3b, it is displaced to the position of normal. That way, the slight burr will be generated, the contour shape of the arm portion, eccentricity and final shape for the three-cylinder engine forged crankshaft including an arrangement angle of the pin portion is shaped to match the crankshaft it can be obtained finish 6 shape.
[0130]
　Others The invention is not limited to the above embodiments, without departing from the scope of the present invention, various modifications are possible. For example, the mechanism for moving the movable journaled axially, in the above embodiment employs a wedge mechanism using a press, but not limited thereto, may be employed a link mechanism, a press a hydraulic cylinder instead of the use of the machine, may be utilized servo motor or the like. As the mechanism for moving the pin-type axially perpendicular direction is not limited to hydraulic cylinders, it may be a servo motor.
[0131]
　In the above embodiment, as a wedge mechanism for moving the movable journaled axially inclined surfaces provided on the end face of the movable journal type, provided the wedge in response to the inclined surface. As a wedge mechanism in place of this, the sides off the first engraved portion and the second engraved portion of the movable journal type, a block having an inclined surface is fixed, it is provided with a wedge corresponding to the inclined surface of the block I do not care.
[0132]
　Further, in the above embodiment, the fixed upper mold support base to the upper hard plate, elastically supports the lower mold support base at the lower hard plates, the wedge is placed on the lower hard plates Te, is a structure in which to move the upper and lower movable journaled in the wedge, may be a structure obtained by inverting the vertically thereto. Below each die support base and elastically supported by each hard plate, installed respectively wedge the hard plate may be configured to move each movable journaled vertically on each wedge.
[0133]
　Further, in the above embodiment, the auxiliary pin type, but moves only in the axial direction is allowed, it may be configured to move is permitted in a direction toward the pin-type paired. In this case, the pin-type and the auxiliary pin type while retaining sandwiched from above and below individually each coarse pin Pa, moves axially perpendicular direction in conjunction with each other.
[0134]
　In the above embodiment, as it is a configuration in which pressing by moving the pin-type axially perpendicular vertical coarse pin portion Pa in the vertical direction, presses the rough pin portion Pa horizontally pin it is also possible to deform the arrangement of the mold and the journal type.
Industrial Applicability
[0135]
　The present invention is useful in the production of forged crankshaft for 3-cylinder engine.
DESCRIPTION OF SYMBOLS
[0136]
　　1: Forged crankshaft, J, J1 ~ J4: journal
　　portion, P, P1 ~ P3: pin, Fr: the front
　　section, Fl: flange portion, A, A1 ~ A6: crank
　　arm, 2: billet 4: the crude
　　material, Ja, J1a ～ J4a: crude journal portion of the crude
　　material, Pa, P1a ～ P3a: rough pin portion of the crude
　　material, Fra: rough front portion of the crude
　　material, Fla: rough flange portion of the crude
　　material, Aa, A1a ~ A6a: crude crank arm portion of the crude
　　material, 5: finish out a material,
　　Jb, J1b ~ J4B: rough journal portion of the material for out
　　finishing, Pb, P1b ~ P3b: coarse pin portion of the material for out
　　finishing, Frb: crude front portion of the finishing out for
　　material, FLB: rough flange portion of the material for out
　　finishing, Ab, A1b ~ A6b: crude crank arm portion of the material for out
　　finishing, 5a: chewing out
　　portion, 6: finish Jc, J1c ~ J4c: journal portion of the finishing
　　material, Pc, P1c ～ P3c: pin end of the
　　finish, Frc: the front part of the finish, Flc: flange portion of the finish,
　　Ac, A1c ~ A6c: crank arm portion of the
　　finish, 7: torsional
　　finish, Jd, J1D ~ J4d: journal portion of the torsion
　　finish, Pd, P1d ~ P3d: pin portion of the torsion
　　finish, Frd: torsional finish the front portion
　　of, Fld: flange portion of the torsion
　　finish, Ad, A1d ~ A6d: crank arm portion of the torsional
　　finish, 9U, 9B: the fixed journal
　　type, 9Ua, 9Ba: first engraved portion of the fixed journal
　　type, 9Ub, 9bb: second engraved portions of the fixed journal type,
　　9Uc, 9bc: third engraved portion of the fixed journal
　　type, 10 U, 10B: movable
　　journaled, 10Ua, 10Ba: first engraved portion of the movable journal
　　type, 10UB, 10Bb: movable second engraved portions of the journal
　　type, 11: reference pin type, 11a: engraved
　　portion, 12: movable pin type, 12a : Engraved
　　portion, 13: auxiliary pin-type, 13a: engraved
　　portion, 14U, 14B: inclined surface of the movable journal type first and fourth coarse
　　journal, 16: hydraulic cylinder,
　　20: lower hard plates 21: the upper hard
　　plate 22: lower mold support base, 23: upper mold support
　　base, 24: elastic member, 25: support column, 26: wedge

WE claims

[Requested item 1]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm in the process of manufacture, the material for out finishing subjected to finishing strike to shape the final shape of the forged crankshaft, an apparatus for forming from a crude material,
　the coarse material,
　each journal portion and the shaft of the forging crankshaft and the length in a direction the same rough journal portion,
　said each pin portion and the length in the axial direction is the same coarse pin portion of the forged crankshaft,
　in response to said third and fourth crank arm portion of the forged crankshaft the crank arm portion and the axial thickness the same third and fourth coarse crank arm portion,
　the Weighted crank arm portion having a balance weight of the forged crankshaft Anda axial thickness is thick Weighted crude crank arm portion than the crank arm in response,
　it said coarse pin portion of the crude material, eccentricity of the axial direction perpendicular said forging eccentricity of the pin portions of the crankshaft are smaller than,
　the molding apparatus,
　is disposed at a position of the second coarse pin portion, with addressed cracking in the coarse pin portion, leading to the rough pin portion while in contact with the side surface of the third and fourth coarse crank arm portion is constrained to movement in the axial direction, the reference pin-type which moves in the axial direction and perpendicular,
　Disposed in said first and said third coarse pin portions of the respective positions of both ends, with addressed cracking each said coarse pin, each, while contacting the side surface of the rough crank arm portion leading to the rough pin portion a movable pin type which moves in the axial direction and axially perpendicular direction toward the reference pin-type,
　is arranged at a position of the rough journal portion connected to said third and fourth coarse crank arm portion, the crude journal parts with individually holding sandwiches from the axial direction and perpendicular to, while in contact with the side surface of each of said third and fourth coarse crank arm, a fixed journal type constrained movement in the axial direction,
　the the third and the lead to fourth coarse crank arm portion is disposed on the rough journal portions of each position other than crude journal portion, or the direction perpendicular axial the crude journal portion individually While sandwiched by the holding, each, while contacting the side surface of the rough crank arm portion leading to the rough journal portion, and a movable journaled to move axially toward the reference pin-type,
　the rough journal part was held sandwiched by the fixed journal type and the movable journal type and the said reference pin type and the movable pin type roughness pin from directed Therefore condition, moves the movable journaled axially , at the same time is moved while moving the movable pin type axially in the axial direction and perpendicular direction by moving the reference pin-type axially perpendicular direction, the axis of the Weighted crude crank arm clamping pressure and a slight proportion its thickness to a thickness of the Weighted crank arm portion of the forged crankshaft direction, the rough pin Parts pressed axially perpendicular direction to increase its eccentricity amount to eccentricity of the pin portion of the forged crankshaft, material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 2]
　In the molding apparatus according to claim 1,
　wherein the reference pin type and the movable pin type, is arranged outside the opposite to the reference pin-type and side where the movable pin mold was We have addressed in each of the coarse pin portion auxiliary pin-type includes,
　the movable journaled, and the with the movement of the movable pin type and the axial direction of the auxiliary pin-type which forms the movable pin type and pair with the movable journal type and the movable after the gap between the pin-type and the auxiliary pin type is closed, so that the rough pin portion for pressing deformation reaches the auxiliary pin-type, the movement control of the movable pin type axial perpendicular direction is the, material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 3]
　In the molding apparatus according to claim 2,
　the movement when the total travel distance in the axial direction perpendicular to the direction of the movable pin type as 100%, the axial direction of the movable journaled adjacent to the movable pin type Once There completion, and the moving distance in the axial direction perpendicular to the direction of the movable pin type than 90% of the total distance, movement in the axial direction perpendicular to the direction of the movable pin mold is completed after this to, the material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 4]
　In the molding apparatus according to any one of claims 1 to 3,
　pressure to the reference pin-type, the movable pin type, the fixed journal type and the movable journal type, in a direction along the axial direction and a direction perpendicular is attached to the can press
　with the pressure of the press, with the fixed journal type and the movable journal type holding sandwich the crude journal portion, the reference pin-type and the movable pin type the addressed to cracking in the coarse pin portion, as with the to continue the reduction of the press, at the same time when the movable journaled moves axially by the individual wedge mechanism, along with the movement of the movable journal type, wherein movable pin type individually moving in the axial direction, the molding device of the material for out finish forging crankshaft for 3-cylinder engine.
[Requested item 5]
　In the molding apparatus according to claim 4,
　wherein the wedge angle of the wedge mechanism different from each other in each of said movable journal type molding apparatus of the material for out finish forging crankshaft for 3-cylinder engine.
[Requested item 6]
　In the molding apparatus according to claim 4 or 5,
　wherein the reference pin type and the movable pin type is connected to the hydraulic cylinder, is moved by driving the hydraulic cylinder in the axial direction and a direction perpendicular, for 3-cylinder engine molding device of the material for out finish forged crankshaft.
[Requested item 7]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm in the process of manufacture, the material for out finishing subjected to finishing strike to shape the final shape of the forged crankshaft, an apparatus for forming from a crude material,
　the coarse material,
　each journal portion and the axial direction of the forged crankshaft and length are the same rough journal portion of
　each pin portion and the axial length is the same coarse pin portion of the forged crankshaft,
　the in response to the third and fourth crank arm portion of the forged crankshaft a crank arm portion and the axial thickness the same third and fourth coarse crank arm,
　the pair crank arm with weights having a balance weight of the forged crankshaft And has an axial thickness is thick Weighted crude crank arm portion than the crank arm portion,
　said first and third coarse pin portion at both ends of the rough material, an axial direction perpendicular eccentricity amount is smaller than √3 / 2 of the eccentricity of the pin portion of the forged crankshaft in directions opposite to each other, the second coarse pin portion of a center of the coarse material, the axial direction perpendicular the eccentricity is zero, or are identical to the eccentricity of the pin portion of the forged crankshaft by the first and the direction perpendicular to the eccentric direction of the third coarse pin portion,
　the molding apparatus,
　is arranged at a position of the second coarse pin portion, with addressed cracking in the coarse pin, while in contact with the side surface of the third and fourth coarse crank arm portion leading to the rough pin portion, the axial movement a constrained reference pin type,
　Disposed on the first and third coarse pins of each position, the addressed cracking each said coarse pin, each, while contacting the side surface of the rough crank arm portion leading to the rough pin, the reference a movable pin type, which moves in the axial direction and axially perpendicular direction toward the pin-type
　individually disposed at the position of the rough journal portion connected to said third and fourth coarse crank arm portion, the crude journal portion the holds sandwich the axial direction and perpendicular, while contacting the side surfaces of each of said third and fourth coarse crank arm, a fixed journal type constrained movement in the axial direction,
　the third and fourth wherein other than the coarse journal portion leading to coarse crank arm portion disposed rough journal portions of each position, sandwiching the axial direction and a direction perpendicular to the crude journal portion individually It holds, each, while contacting the side surface of the rough crank arm portion leading to the rough journal portion, and a movable journaled to move axially toward the reference pin-type,
　the crude journal portion held sandwiched by the fixed journal type and the movable journal type and the said reference pin type and the movable pin type roughness pin from directed Therefore condition, moves the movable journaled axially, wherein by moving the movable pin type and in a direction perpendicular to the axial direction while moving in the axial direction, the Weighted crank arm portion of the forged crankshaft its thickness nipped the Weighted crude crank arm portion in the axial direction a slight proportion to the thickness thereof is pressed in opposite directions to the first and third coarse pin portion in the axial direction and a direction perpendicular Increasing the core weight to √3 / 2 of the eccentricity of the pin portion of the forged crankshaft, material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 8]
　In the molding apparatus according to claim 7,
　wherein the reference pin type and the movable pin type, is arranged outside the opposite to the reference pin-type and side where the movable pin mold was We have addressed in each of the coarse pin portion auxiliary pin-type includes,
　the movable journaled, and the with the movement of the movable pin type and the axial direction of the auxiliary pin-type which forms the movable pin type and pair with the movable journal type and the movable after the gap between the pin-type and the auxiliary pin type is closed, so that the rough pin portion for pressing deformation reaches the auxiliary pin-type, the movement control of the movable pin type axial perpendicular direction is the, material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 9]
　In the molding apparatus according to claim 8,
　the movement when the total travel distance in the axial direction perpendicular to the direction of the movable pin type as 100%, the axial direction of the movable journaled adjacent to the movable pin type Once There completion, and the moving distance in the axial direction perpendicular to the direction of the movable pin type than 90% of the total distance, movement in the axial direction perpendicular to the direction of the movable pin mold is completed after this to, the material forming apparatus for beating finish forging crankshaft for 3-cylinder engine.
[Requested item 10]
　In the molding apparatus according to any one of claims 7-9,
　pressure the reference pin-type, the movable pin type, the fixed journal type and the movable journal type, in a direction along the axial direction and a direction perpendicular is attached to the can press
　with the pressure of the press, with the fixed journal type and the movable journal type holding sandwich the crude journal portion, the reference pin-type and the movable pin type the addressed to cracking in the coarse pin portion, as with the to continue the reduction of the press, at the same time when the movable journaled moves axially by the individual wedge mechanism, along with the movement of the movable journal type, wherein movable pin type individually moving in the axial direction, the molding device of the material for out finish forging crankshaft for 3-cylinder engine.
[Requested item 11]
　In the molding apparatus according to claim 10,
　wherein the wedge angle of the wedge mechanism different from each other in each of said movable journal type molding apparatus of the material for out finish forging crankshaft for 3-cylinder engine.
[Requested item 12]
　In the molding apparatus according to claim 10 or 11,
　wherein is movable pin type is connected to the hydraulic cylinder, it is moved by driving the hydraulic cylinder in the axial direction and perpendicular, finish forging crankshaft for 3-cylinder engine molding apparatus of the material for the strike.
[Requested item 13]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm a method of manufacturing,
　the manufacturing method, first preforming step described below, including a second preforming step, and the finishing beating process, the series of steps:
　according to any one of claims 1 to 6 as the coarse material to be subjected to the molding apparatus, the first and third coarse pin portion at both ends, eccentricity of the pin portion of the forged crankshaft eccentricity of axial and perpendicular directions in opposite directions is the same as √3 / 2 of the second coarse pin portion of the center, said in a direction eccentricity of the axial perpendicular direction perpendicular to the first and eccentric direction of the third coarse pin portion smaller than eccentricity of the pin portion of the forged crankshaft First preforming step shaping the crude material that is;
　using the molding apparatus according to any one of claims 1 to 6, as the finishing out for material, the forged crankshaft including an arrangement angle of the pin portion second preforming step for forming the final shape is material for out finish which is shaped; and
　then hit finish the finishing out for material, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped finishing beating step of molding the finish.
[Requested item 14]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm a method of manufacturing,
　the manufacturing method, first preforming step described below, the second preforming step includes finishing beating process, and twisting processes, the series of steps:
　one of claims 1 to 6, 1 as the coarse material to be subjected to molding apparatus according to claim, wherein the first and third coarse pin portion at both ends, the polarization of the pin portion of the forged crankshaft eccentricity of axial and perpendicular directions in the same direction is smaller than the core volume, the second coarse pin portion of the central, eccentricity of the axial perpendicular direction of the forged crankshaft in a direction opposite to the eccentric direction of the first and third coarse pin portion It is smaller than the eccentricity of the pin portion First preliminary molding step to shape the crude material;
　using the molding apparatus according to any one of claims 1 to 6, as the finishing out material for the final of the forged crankshaft except placement angle of the pin portion second preforming step shape molding a material for striking finish which is shaped;
　Hardcode finishing material for the finishing out, the finish of the final shape of the forged crankshaft except placement angle of the pin portion is shaped molded to finish beating; and
　twisting step of adjusting the arrangement angle of the pin portion of the finish to the arrangement angle of the pin portion of the forged crankshaft.
[Requested item 15]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm a method of manufacturing,
　the manufacturing method, first preforming step described below, the second preforming step, and the finishing beating process comprises a series of steps of:
　according to any one of claims 7 to 12 as the coarse material to be subjected to the molding apparatus, the first and third coarse pin portion at both ends, eccentricity of the pin portion of the forged crankshaft eccentricity of axial and perpendicular directions in opposite directions is smaller than √3 / 2 of the second coarse pin portion of the central, first preforming step shaping the crude material eccentricity of the axial perpendicular direction is zero;
　claims 7 to 12 the forming apparatus according to any one of There, as the finishing out for material, said first and third coarse pin portion at both ends, eccentricity of the axial perpendicular direction in opposite directions of eccentricity of the pin portion of the forged crankshaft is the same as √3 / 2, the second coarse pin portion of the central, second preformed eccentricity of the axial direction perpendicular to the molding material for striking finish that is to remain the same as the coarse material ; and
　then out finishing the first and third coarse pin portion at both ends of the finishing out for material in a state of being in a horizontal posture to press all of the rough pin portion axially perpendicular direction, wherein finishing beating step final shape of the forged crankshaft including an arrangement angle of the pin portion is molded finish that is shaped.
[Requested item 16]
　A forged crankshaft for 3-cylinder engine, has no balance weight to the third and fourth crank arm connected to the second pin of the central, forged crankshaft having a balance weight to the remainder of the crank arm a method of manufacturing,
　the manufacturing method, first preforming step described below, the second preforming step, and the finishing beating process comprises a series of steps of:
　according to any one of claims 7 to 12 as the coarse material to be subjected to the molding apparatus, the first and third coarse pin portion at both ends, eccentricity of the pin portion of the forged crankshaft eccentricity of axial and perpendicular directions in opposite directions is smaller than √3 / 2 of the second coarse pin portion of the center, said in a direction eccentricity of the axial perpendicular direction perpendicular to the first and eccentric direction of the third coarse pin portion same and eccentricity of the pin portion of the forged crankshaft First preforming step shaping into the coarse material;
　using the molding apparatus according to any one of claims 7 to 12, as the finishing out for material, said first and third coarse pin portion at both ends is the same as √3 / 2 of the eccentricity of the eccentric amount of axial and perpendicular directions in opposite directions the pin portion of the forged crankshaft, said second coarse pin portion of the central, axial and; second preforming step eccentricity direction and perpendicular to mold the same leave been finishing out for materials and the crude material
　the first and third coarse pin portion at both ends of the finish out the material for the was out finish while the horizontal posture, to press the first and third coarse pin portion axially perpendicular direction, the final shape of the forged crankshaft including an arrangement angle of the pin portion is shaped finishing beating step of molding the finish was.