Technical field
[0001]The present invention relates to a method of manufacturing a crank shaft by hot forging.
BACKGROUND
[0002]Automobiles, motorcycles, in agricultural machinery or reciprocating engine of a ship or the like, in order to convert the reciprocating motion of the piston into rotational movement takes power, the crankshaft is essential. Crankshaft can be produced by die forging or casting. When the high strength and high rigidity are required to the crankshaft, a crankshaft manufactured by die forging (hereinafter, also referred to as "forging crankshaft") is often used.
[0003]In general, raw materials forged crankshaft is billets. In that billet cross section is round or square, is constant cross-sectional area over the entire length. Manufacturing process of forging the crank shaft includes a pre-molding step, the mold forging step and burr punching process. If necessary, shaping step is added after the burr punching process. Usually, preforming step includes the steps of stamping and bending roll forming, die forging step comprises the steps of rough beating and finishing beating.
[0004]
　Figure 1A ~ FIG. 1F is a schematic diagram for explaining a conventional general forged crankshaft manufacturing process. Figure 1A is a billet, Figure 1B is a roll wasteland, Figure 1C the bending wasteland, Figure 1D rough forged material, FIG. 1E finish forged material, FIG. 1F shows crankshaft (final product), respectively. Forged crankshaft 1 illustrated in FIG. 1F is mounted on four-cylinder engines. Part crankshaft 1 includes five journal portions J1 ~ J5, four pin portions P1 ~ P4, the front portion Fr, and the flange portion Fl, 8 sheets of the crank arm portion (hereinafter, simply referred to as "arm" ) includes an A1 ~ A8, the. The arm A1 ~ A8 is, connecting the journal portion J1 ~ J5 and the pin portion P1 ~ P4, respectively. Also, all of the arm portions A1 ~ A8 includes counterweight unit (hereinafter, simply referred to as "weight part") W1 ~ W8 the integrally respectively.
[0005]
　Hereinafter, when collectively each journal portion J1 ~ J5, pin P1 ~ P4, the arm portions A1 ~ A8, and the weight portion W1 ~ W8, the sign, in the journal portion "J", a pin portion "P" , also referred to as "a", "W" in the weight portion in the arm portion. Together a pair of arm portions A (including the weight portion W) which leads to the pin portion P and the pin portion P is also referred to as "slow".
[0006]
　In the manufacturing method shown in FIGS. 1A ~ FIG 1F, forged crankshaft 1 is manufactured as follows. First, after heating the billet 2 of predetermined length, as shown in FIG. 1A by a heating furnace (e.g., an induction heating furnace or gas heating furnace or the like), and roll forming. The roll forming process, for example, rolling a billet 2 with grooved rolls, thereby reducing the cross-sectional area in a part of the length of the billet 2. Thus, allocating the volume of the billet 2 in the longitudinal direction to obtain a roll wasteland 3 is an intermediate material (see FIG. 1B). Next, in the bending beating process, the roll wasteland 3 partially pressure from a direction perpendicular to a longitudinal direction, thereby decentering the part of the length of the roll wasteland 3. Thus, allocating the volume of the roll wasteland 3, it is a further intermediate material bending obtain wasteland 4 (see FIG. 1C).
[0007]
　Subsequently, the rough beating process, obtained by pressing forging, rough forged material 5 with bent wasteland 4 a pair of molds (upper and lower dies) (see FIG. 1D). Rough forged material 5 obtained has the approximate shape of a crank shaft (final product). Furthermore, the finishing beating process, by press forging using a pair of molds rough forged material 5 up and down to obtain a finish forged material 6 (see FIG. 1E). Resulting finish forged material 6 has a shape that matches the crankshaft of the final product. When these rough beating and finishing beating, surplus material, the burrs to flow out from the gap between the upper and lower molds. Therefore, none of the rough forging 5 and the finishing forging 6, has a large burr B around.
[0008]
　The burr punching step, for example, the finish forged material 6 with burrs while maintaining across the pair of molds, punching burrs B by blade type. Thus, to remove the burr B from the finish forged material 6 to obtain the burrs without forging. Burr without forging is substantially the same shape as the forged crankshaft 1 shown in FIG. 1F.
[0009]
　The shaping step, slightly rolling a die key points of burrs without forging from above and below, to correct the burr without forging the dimensions of the final product. Here, the key point of burrs without forging, for example, a journal portion J, the pin portion P, a front portion Fr and the axial portion, such as flange portion Fl, more arm portions A and the weight portion W. Thus, forged crankshaft 1 is manufactured.
[0010]
　Manufacturing process shown in FIGS. 1A ~ FIG 1F is not limited to the crank shaft of a four-cylinder -8 Like counterweight shown in Fig. 1F, can be applied to various crankshaft. For example, it can be applied to the crankshaft of a four-cylinder -4 Like counterweight.
[0011]
　4 If the crankshaft of the cylinder -4 sheets counterweight, a portion of the arm portion A of the eight arm portions A having a weight portion W integrally. For example, the first arm portion A1 of the top eighth arm portions A8 and two arm portions of the center of the last (fourth arm A4, the fifth arm A5) has a weight portion W. Further, the remaining arm portions A, specifically, the second arm portion A2, the third arm A3, the sixth arm portion A6 and the seventh arm A7 has no weight portion. In the following, "the arm there is weight," the arm portion having a weight portion, an arm portion which does not have the weight portion is also referred to as "the weight without the arm."
[0012]
　In addition, three-cylinder engine, series 6-cylinder engine, even crankshaft mounted in V-type 6-cylinder engine and 8-cylinder engine or the like, the manufacturing process is the same. Incidentally, when the adjustment of the arrangement angle of the pin portion is required, after the burr punching process, twisting process is added.
[0013]
　In the manufacture of such forging crankshaft, by reducing the outflow of burrs in the mold forging, it is desirable to improve the material yield. Here, the material yield, the volume of the forged crankshaft (final product) means a proportion (percentage) occupying the volume of the billet. The material yield is at preforming, by promoting the distribution of the volume, can be improved.
[0014]
　Technology related preformed, JP 2001-105087 (Patent Document 1), is described in JP-A 2-255240 (Patent Document 2) and JP 62-244545 (Patent Document 3).
[0015]
　Patent Document 1, preforming method using a pair of upper and lower molds are described. In that pre-molding method, when the reduction of the workpiece rod-shaped with the upper and lower molds, while reducing the cross-sectional area by extending a portion of the workpiece, slide the other portion continuous to a portion while to the eccentric move. In such Patent Document 1 preforming method according to, and from can be implemented extend and bend simultaneously, can provide a small preformed method of capital investment.
[0016]
　The preform according to Patent Document 2, instead of the roll forming of a conventional two-pass, using a high-speed roll equipment 4 pass. In its preformed, the cross-sectional area of ​​the roll wasteland, the weight portion of the forged crankshaft (final product), be determined in accordance with the distribution of the cross-sectional area of ​​the arm portion and the journal portion has been proposed. Accordingly, in Patent Document 2, and it can be improved material yield.
[0017]
　The preform according to Patent Document 3, to allocate the volume by cross rolling method in the axial direction and the radial direction, obtaining axially asymmetric intermediate material. The cross rolling method, reduction of the round bar material with two dice, allocating the volume by rolling action of the dies.
CITATION
Patent Document
[0018]
Patent Document 1: JP 2001-105087 Patent Publication
Patent Document 2: JP-A 2-255240 Patent Publication
Patent Document 3: JP 62-244545 Patent Publication
Patent Document 4: International Publication 2014/038183 Patent Laid
Summary of the Invention
Problems that the Invention is to Solve
[0019]
　In the manufacture of forged crankshaft, as described above, to reduce the outflow of burrs in the mold forging, it is desired to improve the material yield.
[0020]
　As in the manufacturing process shown in FIGS. 1A ~ FIG 1F, there is a case where preforming consists roll forming and bending beating. In this case, to ensure the material volume of the portion to be a weight portion, the bending beating, a portion the pin portion, and, by pressure of the portion to be a pair of arm portions which connect with the pin unit, those sites the eccentric direction of the pin portion is decentered in the opposite direction.
[0021]
　In the following, "Journal equivalent part" a portion to be a journal portion, "pin-corresponding portion" a portion to be a pin, "arms corresponding portion" a portion to be the arm part, and the pin corresponding portion and the pin portion corresponding a pair of arm portions become the site (containing the site to be the weight portion) connected also referred to as "slow-corresponding portion".
[0022]
　However, in the above method, is decentered in a direction opposite to the eccentric direction of the pin portion throws corresponding portion by bending stamped. Thus, in the die forging, the material volume of the position of the pin portion and the eccentric direction of the pin portion for biased in the opposite direction, many burrs around the pin portion is generated. To prevent underfill of the pin portion at the die forging, because it is necessary to increase the volume of the slow substantial portion (including the pin-corresponding portion). As a result, improvement of the material yield can not be expected.
[0023]
　Wherein in the preformed method described in Patent Document 1, in the same manner as above, it is decentered in a direction opposite to the eccentric direction of the pin portion slow-corresponding portion. Therefore, improvement of the material yield can not be expected.
[0024]
　Wherein in the preformed method described in Patent Document 2, since it is roll forming, it can not be offset a portion of the billet. Therefore, the roll wasteland obtained, it is necessary to further apply a clinched like. In this case, as described above, improvement of the material yield can not be expected.
[0025]
　Wherein in the preformed described in Patent Document 3, to allocate the volume by cross rolling method in the axial and radial directions. The cross rolling method, rather than a press machine used in bending stamped or die forging or the like, using special equipment. Also, the cross rolling method, it is difficult to process a plurality of locations at the same time, for example, a plurality of journal equivalent portions and a plurality of the slow portion corresponding order, so that the processing. For this reason, the die is increased in size. From these, the equipment cost is increased.
[0026]
　An object of the present invention, while suppressing an increase in equipment cost, is to provide a method for producing a forged crankshaft can improve material yield.
Means for Solving the Problems
[0027]
　Method for producing a forged crankshaft according to an embodiment of the present invention includes a plurality of journal portion as a rotational center, and a plurality of pin portions eccentric to the plurality of journal portions, and a plurality of journal portions and a plurality of pin portions a plurality of crank arm portion connecting the a method for producing a forged crankshaft with a. The production method held by sandwiching the first region is a part of the length of the rod-like member by the first mold pair, the steps scissors holds the first portion, the first portion by the first mold in state includes an eccentric step of decentering the second portion of the rod-like member by the second die, the. The second portion is at least one pin corresponding portion of the plurality of pins corresponding portion comprising a plurality of pin portions. The first site, of a plurality of arms corresponding portion comprising a plurality of crank arm portion, a plurality of arms corresponding portion the pin portion corresponding contacts of the second portion. Eccentric direction of the second mold, the direction sandwiching the first mold, and a respective perpendicular direction of the longitudinal direction of the bar-like member is the same direction as the eccentric direction of the corresponding pin portion.
The invention's effect
[0028]
　According to the production method of the present invention for producing a forged crankshaft, the pin corresponding section, is decentered in the eccentric direction of the corresponding pin portion. Thus, in the die forging, since the material volume of the position of the pin portion is biased in the same direction as the eccentric direction of the pin portion, underfill of the pin portion is unlikely to occur. Then, it is possible to reduce the material volume of the pin corresponding portion. As a result, it is possible to improve the material yield. The manufacturing method of the present invention can be carried out using a press machine. Therefore, it is possible to suppress the increase in equipment cost.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
[Figure 1A] Figure 1A is a schematic diagram showing the billet in conventional general forged crankshaft manufacturing process.
FIG 1B] Figure 1B is a schematic diagram showing a roll wasteland in a conventional typical forged crankshaft manufacturing process.
[Figure 1C] Figure 1C is a schematic diagram showing a wasteland bending in a conventional typical forged crankshaft manufacturing process.
[Figure 1D] Figure 1D is a schematic diagram showing a rough forged material in a conventional typical forged crankshaft manufacturing process.
FIG 1E] FIG. 1E is a schematic diagram showing a finishing forging material in a conventional typical forged crankshaft manufacturing process.
[FIG. 1F] FIG. 1F is a schematic diagram showing a crankshaft in a conventional typical forged crankshaft manufacturing process.
[Figure 2A] Figure 2A is a longitudinal sectional view showing a pre-start scissors in the processing flow example by scissors step and the eccentric step.
[Figure 2B] Figure 2B is a longitudinal sectional view showing a the end scissors in the processing flow example in steps and the eccentric step scissors.
[Figure 3A] Figure 3A is a top view showing a at the end scissors in the processing flow example by scissors step and the eccentric step.
[Figure 3B] Figure 3B is a top view showing a time eccentric ends in the processing flow example in steps and the eccentric step scissors.
[Figure 4A] Figure 4A is a cross-sectional view taken along line IVA-IVA of FIG. 3A.
[Figure 4B] Figure 4B is a cross-sectional view taken along line IVB-IVB of FIG. 3A.
[Figure 4C] Figure 4C is a cross-sectional view taken along line IVC-IVC in FIG. 3A.
[Figure 5A] Figure 5A is a cross-sectional view taken along line VA-VA in FIG. 3B.
[Figure 5B] Figure 5B is a cross-sectional view taken along line VB-VB in Figure 3B.
[Figure 5C] Figure 5C is a cross-sectional view taken along line VC-VC in FIG. 3B.
FIG. 6 is a top view showing a rod-like member at the eccentric ends in the processing flow example by scissors step and the eccentric step.
[Figure 7A] Figure 7A is a cross-sectional view showing a modification of the first mold, showing the cross-sectional shape of the end of the journal portion.
[Figure 7B] Figure 7B is a cross-sectional view showing a modification of the first mold, showing the cross-sectional shape of the end of the pin portion.
[8] FIG. 8 is a cross-sectional view showing a modified example of the second mold.
FIG 9A] FIG 9A is a cross-sectional view showing a pre-start scissors in the configuration example using a wedge mechanism.
[FIG. 9B] FIG 9B is a cross-sectional view showing a the end scissors in the configuration example using a wedge mechanism.
FIG 9C] FIG 9C is a cross-sectional view showing the operation of the second die in the configuration example using a wedge mechanism.
DESCRIPTION OF THE INVENTION
[0030]
　It will be described below embodiments of the present invention. In the following description, will be described by way of example embodiments of the present invention, the present invention is not limited to the examples described below.
[0031]
　Manufacturing method of the present embodiment is a method for producing a forged crankshaft. Its forged crankshaft, a plurality of journal portion J as a center of rotation, a plurality of pin portion P which is eccentric with respect to a plurality of journal portions J, a plurality of connecting the plurality of journal portions J and a plurality of pin portion P comprising a crank arm portion a, a. The manufacturing method of this embodiment includes a a scissors Step eccentric step.
[0032]
　Pinching step, by sandwiching the first region is a part of the length of the rod-like member by the first mold pair, it is a step of holding the first part. When sandwiching the first region by the first mold, the first portion may be pressure by the first mold. The first site is in a state of being held by the first mold, the next eccentric step is performed.
[0033]
　Rod-like members sandwiched by sandwiching step is a member made of a material of the forged crankshaft. The said rod-like member, it is possible to use a material called as the above-described billet.
[0034]
　Eccentric step, while holding the first portion by a first mold, a step of decentering the second portion of the rod-like member by the second mold. Here, the second portion is at least one pin corresponding portion of the plurality of pins corresponding portion comprising a plurality of pin portions. The first site, of a plurality of arms corresponding portion comprising a plurality of crank arm portion, a plurality of arms corresponding portion the pin portion corresponding contacts of the second portion. That is, when setting the first portion and second portion, at least one slow-corresponding portion of the plurality of slow-corresponding portion is selected. Pins corresponding portion included in the thrown equivalent portion selected as the second portion, to a pair of arms corresponding portion included in the thrown equivalent part to the first part. In one example, all of the slow substantial portion is selected, all the pins corresponding portion and the second portion, to all of the arm portion corresponding to the first site.
[0035]
　Eccentric direction of the second mold (eccentric direction of the eccentric step), the direction sandwiching the first mold (direction scissors in scissors step), and a respective perpendicular direction of the longitudinal direction of the rod-like member, the corresponding is the same direction as the eccentric direction of the pin portion. In a typical example, the pinching step, the first mold is moved in the vertical direction, the second mold is moved mainly in a horizontal direction in an eccentric step.
[0036]
　According to the manufacturing method of this embodiment, while holding a pair of arms corresponding portion in contact with the pin-corresponding portion, the pin corresponding portion is eccentric to the eccentric direction of the corresponding pin portion. Thus, in the die forging, since the material volume of the position of the pin portion is biased in the same direction as the eccentric direction of the pin portion, underfill of the pin portion is unlikely to occur. Then, it is not necessary to secure the material volume of the pin corresponding portions excessively as in the prior art. Therefore, it is possible to reduce the material volume of the pin corresponding portion. As a result, it is possible to improve the material yield. The manufacturing method of this embodiment may be implemented using a pressing machine. Therefore, it is possible to suppress the increase in equipment cost.
[0037]
　When to eccentric pins corresponding portion by the second die, if holding the arm corresponding portion by the first mold, it can be effectively offset only pin-corresponding portion. Furthermore, it is possible to suppress excessive deformation of the arm portion corresponding to contact with the pin-corresponding portion. Without if holding of the arm portion corresponding the first mold, with the eccentric movement of the pin corresponding portion of the second mold, the arm corresponding portion is deformed at random.
[0038]
　In the production method of the present embodiment, the first portion further comprises of a journal portion corresponding to a plurality of journal portions may include a journal portion corresponding to the arm corresponding portion as the first portion is in contact. That is, a pair of arms corresponding unit included in the thrown equivalent portion selected, and the journal equivalent portions of the arm portion corresponding contacts may be first site. In this case, the first part of the holding by the first mold is further stabilized. Therefore, it is possible to effectively offset the second portion (pin portion corresponding) in an eccentric step.
[0039]
　In the production method of the present embodiment, at least one of the plurality of arm portions may be a arm there weight having a weight portion. In this case, the first site may comprise an arm corresponding portion there weight becomes the weight there arm. In this case, sandwiching step, by reduction of the first portion (wait there arm equivalent portion) by the first mold, the first portion, opposite to the eccentric direction of the corresponding pin portion direction (the weight of the it may be flared in the eccentric direction). Because it can be secured material volume of the weight portion.
[0040]
　Hereinafter, an example of a method for manufacturing the forged crankshaft of the present embodiment will be described with reference to the drawings. The embodiments described below are exemplary, at least a portion of the configuration in the following embodiment, can be replaced with the above-described configuration.
[0041]
1. Manufacturing process Example
　forged crankshaft manufacturing method of this embodiment is the subject connects the journal portion J which is a rotation center, and the pin portion P which is eccentric with respect to the journal portion J, the journal portion J and the pin portion P It comprises an arm section a, a. Some or all of the arm portion A is provided with a weight portion W. The manufacturing method of this embodiment, for example, can be directed to a crankshaft of a four-cylinder -8 Like counterweight shown in FIG 1F. It is also possible to target the crankshaft of a four-cylinder -4 sheets counterweight above. Alternatively, it is also a three-cylinder engine, to be directed to a crankshaft mounted in series 6-cylinder engine, V-type 6-cylinder engine or an eight-cylinder engine or the like.
[0042]
　Method for producing a forged crankshaft of the present embodiment includes a step scissors, an eccentric step. The scissors step sandwich the longitudinal part of the rod-like member (first portion) by a first mold pair, retains some such. The eccentric step, while holding the first portion by the first mold, the second mold, is decentered longitudinal part of the rod-shaped member (second part). Details of scissors steps and the eccentric step, described below.
[0043]
　Processing consisting of scissors steps and the eccentric step of the present embodiment corresponds to preforming of the conventional manufacturing process, and more specifically, corresponds to a preformed consisting roll forming and bending beating. Roll forming and bending beating is carried out respectively by a different equipment, but in the manufacturing method of this embodiment, the processing consisting of scissors steps and eccentric step can be carried out in a single press machine.
[0044]
　Rod-like member is a workpiece, for example, can be a billet. Alternatively, it can be an initial wasteland with reduced cross-sectional area in a part of the length. Its initial wasteland, for example, obtained by performing the roll forming or the like billets.
[0045]
　After preforming, for example, similarly to the manufacturing process shown in FIG. 1D ~ Figure 1F, it can be added to the die forging process and burr punching process, if necessary, add shaping step after the burr punching process. Die forging step may be comprised of rough stamped and finishing beating. Incidentally, when the adjustment of the arrangement angle of the pin portion is required, after the burr punching process, twisting process is added. These steps are all carried out in a series between heat.
[0046]
　Alternatively, as a step after the preforming, it may be added step of processing the molding apparatus described in WO 2014/038183 (Patent Document 4). Patent Document 4, the molding apparatus for molding materials for striking finish from a crude material roughness shape of the crankshaft is shaped is proposed. As a crude material, using a wasteland obtained by pinching step and the eccentric step. In this case, after the step of processing by the above forming apparatus, may be added finishing forging step and burr punching step may be to add a shaping step as needed. These steps are all carried out in a series between heat.
[0047]
　Usually, when manufacturing the crankshaft for 4-cylinder engines, twisting step is omitted. By the finishing forging, because including the placement angle of the pin portion the shape of the final product obtained. The crankshaft for a four-cylinder engine, the arrangement angle of the pin portion is 180 °. Therefore, in an eccentric step, the eccentric direction of the second mold (the direction to decenter the second portion (pin portion corresponding)) are entirely consistent with the eccentric direction of the corresponding pin portion.
[0048]
　The crankshaft for 3-cylinder engine, the arrangement angle of the pin portion is 120 °. When manufacturing a crankshaft for a three-cylinder engine, there are two variations of the following. First, by the finishing forging, the case where, except the arrangement angle of the pin portion the shape of the final product obtained. First and a third pin portion corresponding to the third pin portion of the three pin portions (first to third pin portion) is set as the second region. In this case, these a first pin portion arranged angle of the third pin portion of the resulting finish forged material is 180 °. Therefore, in an eccentric step, the eccentric direction of the second mold (the direction to decenter the second portion (pin portion corresponding)) are entirely consistent with the eccentric direction of the finishing forging corresponding pin portion. In this case, for the final adjustment of the arrangement angles of the first and third pin portion, twisting step is added.
[0049]
　Second, by the finishing forging is when including the placement angle of the pin portion the shape of the final product obtained. In this case, the arrangement angle of the pin portion of the resulting finish forged material is 120 °. Therefore, in an eccentric step, the eccentric direction of the second mold (the direction to decenter the second portion (pin portion corresponding)) substantially coincides with the eccentric direction of the finishing forging corresponding pin portion. Strictly speaking, the first and third pins corresponding portion serving as the first and third pin portion of the three pin portions (first to third pin portion) is set as the second region. In eccentric step, the eccentric direction of the second mold (second site (the first and third pins corresponding section) direction to decenter the) from the eccentric direction of the corresponding pin portion (first and third pin portion) 30 ° displaced. In this case, final adjustment of the arrangement angle of the pin portion is not required, the twisting step is omitted.
[0050]
　The crankshaft for straight-six engine, the arrangement angle of the pin portion is 120 °. Therefore, when manufacturing a crankshaft for straight-six engine, becomes similar to the case that variations of manufacturing a crankshaft for 3-cylinder engine.
[0051]
　In the present specification, the "same direction as the eccentric direction of the pin portion" relates to the eccentric direction of the second mold, as well to mean a direction which exactly matches the eccentric direction of the pin portion, the eccentric direction of the further pin portion some (eg: 30 °) from also means in a direction deviating.
[0052]
2. Scissors step and the eccentric step
　for processing flow example by scissors step and the eccentric step will be described with reference to the drawings. This processing flow example is directed to the crankshaft of a four-cylinder -8 sheets counterweight.
[0053]
　Figure 2A ~ 6 are schematic views showing a processing flow example by scissors step and the eccentric step. Figures 2A and 2B of which is a longitudinal sectional view, FIG. 2A shows a front start scissors, Figure 2B shows the time scissors ends. FIG 2A and FIG 2B is omitted, the rod-like member 51 (billet), shows a first mold 10 of the pair, to facilitate the understanding of the drawings, the second mold to be described later.
[0054]
　3A and 3B, a top view, FIG. 3A shows a time scissors completion, Figure 3B shows the time offset ends. FIG 3A and 3B, the first upper die 11 of the rod-shaped member 51, wasteland 52, first mold 10 of the pair, and show a second die 20. To facilitate understanding of the drawings, in FIGS. 3A and 3B, respectively hatching first upper die 11 and second die 20 is subjected.
[0055]
　FIGS. 4A ~ 4C are cross-sectional view showing a state at the end (the eccentric before start) scissors. Figure 4A is a cross-sectional view taken along the line IVA-IVA of FIG. 3A, FIG. 4B is a cross-sectional view taken along the line IVB-IVB of FIG. 3A, FIG. 4C is a cross-sectional view along line IVC-IVC in FIG. 3A. Further, FIGS. 5A ~ 5C are cross-sectional views showing a state when the eccentric ends. 5A is a cross-sectional view taken along the line VA-VA in FIG. 3B, FIG. 5B is a cross-sectional view taken along the line VB-VB in FIG. 3B, FIG. 5C is a cross-sectional view along line VC-VC in FIG. 3B. 4A and 5A shows a cross-sectional shape of the journal portion of the end of the first mold, 4B and 5B show cross-sectional shape of the pin portion of the end of the first mold. 4C and 5C show the cross-sectional shape of the second mold.
[0056]
　Figure 6 is a top view showing an eccentric end of the rod-like member (wasteland 52). The bottom of FIG. 6, with different parts of wasteland 52, to indicate the correspondence between each part of the forged crankshaft (final product) shows the shape of a forged crankshaft 1 in phantom.
[0057]
　In this processing flow example, the first die 10 of the pair is constituted by a first upper die 11 and the first lower die 12. The first upper die 11 is fixed to the upper base plate of the press (not shown), the first lower die 12 is fixed to the lower base plate of the press (not shown).
[0058]
　The first mold 10 is arranged at a position of the first portion 51a of the rod-like member 51 (billet). In this processing flow example, site comprising an arm portion (arm equivalent portion) becomes the first portion 51a (see FIG. 6). Such pair of first mold 10, sandwiching the first region 51a, and holds the first portion 51a.
[0059]
　In this processing flow example, the first die 10, the range corresponding to the site (pin equivalent part) serving as a pin portion among the slow-corresponding portion is opened. Moreover, the range corresponding to the site (journal equivalent portions) serving as a journal portion is also opened. Range corresponding to the site of the site and the flange portion as the front portion is also opened.
[0060]
　At least a portion of their open range, the second die 20 is disposed. Specifically, the second die 20 is disposed at a position of the second portion 51b. In this processing flow example, the pin corresponding portion of the slow-corresponding portion is the second portion 51b (see FIG. 6). By its second die 20, thereby decentering the second portion 51b. The second die 20, the direction scissors according to the first mold 10, and, a respective perpendicular direction of the longitudinal direction of the bar-like member 51, the same direction as the eccentric direction of the corresponding pin portion (hatching in FIG. 3B it is movable along the arrow reference) which has been subjected.
[0061]
　Here, the first upper die 11 and the first lower mold 12 (first mold 10) includes respective concave mold engraved portion to sandwich the first portion 51a of the above. Cross-sectional shape of the mold engraving unit, for example, parabolic, semi-elliptical or semicircular. Specifically, with reference to FIGS. 4A and 5A, at the end of the journal portion of the first die 10, the cross-sectional shape of the mold engraved portion is, for example, semicircular. The journal portion of the first portion 51a, in order to restrain the range of the eccentric direction side of the second portion 51b (pin equivalent part) by the first mold 10. On the other hand, with reference to FIGS. 4B and 5B, at the end of the pin portion of the first die 10, the cross-sectional shape of the mold engraved portion is, for example, a semi-elliptical shape. The pin side of the first portion 51a, in order to open the range of the eccentric direction side of the second portion 51b (the pin-corresponding portion) from the first mold 10. Thus, in the mold engraved portion of the first mold 10, at least a range as the eccentric direction side of the second portion 51b (the pin corresponding portion) is expanded from the journal portion toward the pin side (FIG. 3A and see the dotted line in FIG. 3B).
[0062]
　The second mold 20 has a mold engraved portion of the concave in order to decentering of the second portion 51b of the above. Cross-sectional shape of the mold engraving unit, for example, parabolic, semi-elliptical or semicircular. Specifically, with reference to FIGS. 4C and 5C, the cross sectional shape of the mold engraved portion of the second die 20 is, for example, semicircular. The eccentric direction of the second portion 51b of the second portion 51b (pin equivalent part) in order to constrain the range on the opposite side by the second die 20.
[0063]
　Scissors step and the eccentric step can be performed as follows using the first mold 10 and second mold 20 described above.
[0064]
　With the operation of the press, is separated from the first upper die 11 and the first lower mold 12, on the first lower mold 12, the cross-sectional shape for mounting the rod-shaped member 51 is circular (see Figure 2A). At that time, the second die 20, in order to prevent interference of the rod 51 is retracted.
[0065]
　Then, the scissors step, lowers the first upper die 11 with the operation of the press. By the lowering of the first upper die 11, the first upper die 11 and the first lower die 12 sandwich the first portion 51a of the rod 51. When the first upper die 11 reaches the bottom dead center, scissors step is completed (see FIG. 2B, FIG. 4A ~ view and FIG. 3A, 4C). As a result, the first portion 51a is held by the first mold 10 (the first upper die 11 and the first lower die 12). In this processing flow, the cross-sectional shape of the first portion 51a is not deformed while the circular (see FIG. 4A and FIG. 4B).
[0066]
　The eccentric step, by maintaining the position of the first upper die 11 to the bottom dead center, pinching and holding the first portion 51a of the rod 51 in the first mold 10 of the pair. In this state, by moving the second mold 20 is pressed against the rod-shaped member 51. By further moving the second die 20, thereby decentering the second portion 51b (see FIGS. 3B and 5A ~ FIG 5C,). At that time, in one of the slow-corresponding portion, since the two first portions 51a in contact with one of the second portion 51b (pin equivalent part) (arm equivalent portion) is held by the first mold 10, a second gold thereby decentering the second portion 51b (pin equivalent part) by the mold 20. In this way, as shown in FIG. 6, wasteland 52 pin corresponding portion (second portion 51b) is decentered in the eccentric direction of the pin portion is formed.
[0067]
　In the pin portion of the first portion 51a (arm equivalent portion), range of the eccentric direction side of the second portion 51b (the pin corresponding portion) is released from the first mold 10. Therefore, in an eccentric step, the material flows from the second portion 51b to the first portion 51a. Therefore, range of the eccentric direction side of the second portion 51b within the first portion 51a is smoothly connected to the second portion 51b.
[0068]
　After eccentric completion, it retracts the second die 20, thereby raising the first top die 11. In this state, the wasteland 52 is taken out to be conveyed to a subsequent step. The rough beating and finishing beating in a later step, to die forging the wasteland 52. This die forging, the material volume of the position of the pin portion (the volume of the second portion 51b) is biased in the same direction as the eccentric direction of the pin portion. Therefore, it is possible to reduce the outflow of burrs and improve the material yield.
[0069]
　As described above, the operation by the first mold 10 of the pair, can be achieved by a press machine. Operation of the second die 20, for example, below the wedge mechanism, or can be realized by a hydraulic cylinder or the like. Therefore, the pinching step and the eccentric step, can use existing presses, special equipment like a cross rolling method is required. Therefore, it is possible to suppress the increase in equipment cost.
[0070]
　Also, as in the processing flow example described above, in one stroke of the press machine (1 reciprocates), can be performed scissors steps and the eccentric step. Thus, while maintaining or improving the manufacturing efficiency can be improved material yield.
[0071]
　The first portion 51a may further include a journal portion corresponding. In this case, the holding of the first portion 51a of the first mold is further stabilized.
[0072]
　Also, all of the arm portion may be a arm there weight, an arm there a part of the arm portion weight, the rest of the arm portion may be weight without arm. In this case, sandwiching step, by reduction of the first portion (wait there arm equivalent portion) by the first mold, the first portion, opposite to the eccentric direction of the corresponding pin portion direction (the weight of the it may be flared in the eccentric direction). Thus, while suppressing the volume of the pin corresponding portion, it can be secured material volume at the site to be the weight section. As a result, it is possible to improve the material yield.
[0073]
　From the viewpoint of securing the material filling of to pin die engraving unit in the die forging, eccentricity E1 of the pin corresponding portion of wasteland 52 (mm), the eccentricity of the pin portion of the eccentric amount of the finished size (forged crankshaft an amount) E0 (mm) ratio (E1 / E0) for preferably set to (1.0-Dp / 2 / E0 ) to 1.0 (see Figure 6). Here Dp means the diameter of the pin portion of the finished size (the diameter of the pin portion of the forged crankshaft). From the same viewpoint, the cross-sectional area of the pin corresponding portion of wasteland 52 Sp1 (mm 2 ), the cross-sectional area of the pin portion of the forged crankshaft Sp0 (mm 2 in ratio) (Sp1 / Sp0), 0.7 or 1. preferably 5 or less. More preferred ratios (Sp1 / Sp0) is 0.75 to 1.1.
[0074]
　Cross-sectional shape of the first die 10 and second die 20 is not limited to the above shape. A modification of the first mold 10 and second mold 20 will be described with reference to the drawings.
[0075]
　7A and 7B are a cross-sectional view showing a modification of the first mold. Figure 7A shows a cross-sectional shape of the journal portion of the end of the first mold, corresponding to the cross-sectional view taken along line IVA-IVA of FIG. 3A. Figure 7B shows a cross-sectional shape of the pin portion of the end of the first mold, corresponding to the cross-sectional view taken along line IVB-IVB of FIG. 3A.
[0076]
　Referring to FIGS. 7A and 7B, mold engraved portion of the first upper die 11 and the first lower mold 12 (first mold 10), the eccentric direction of the second portion 51b (the pin corresponding portion) and the opposite side It is open the range of. This is because no effect on the retention of the first portion 51a of an eccentric step.
[0077]
　Figure 8 is a cross-sectional view showing a modification of the second mold. Figure 8 shows a cross-sectional shape of the second mold corresponding to the cross-sectional view taken along line IVC-IVC in FIG. 3A.
[0078]
　Referring to FIG. 8, the second mold 20 is composed of a second upper die 21 and the second lower die 22. In this case, the cross-sectional shape of the mold engraved portion of the second upper die 21 and the second lower mold 22 (second mold 20) is, for example, a semicircular. However, it may be opened a distance to the eccentric direction side of the second portion 51b (the pin corresponding portion). This is because not affect the eccentric action of the second portion 51b of the eccentric step.
[0079]
　As described above, the operation of the second die 20, for example, below the wedge mechanism, or can be realized by a hydraulic cylinder or the like. With operating the second mold reliably synchronized with reciprocation of the press, from the viewpoint of realizing a high speed operation, it is preferable to operate the second die by the wedge mechanism. Hereinafter, a configuration example of a case of operating the second die by the wedge mechanism will be described with reference to the drawings.
[0080]
　Figure 9A ~ 9C are a cross-sectional view schematically showing a configuration example of a case of operating the second die by the wedge mechanism, 9A before the start pinching, at Figure 9B scissors ends, FIG. 9C is a indicating when the second mold operation, respectively. FIG 9A ~ FIG 9C, showing a portion of the press 40, the rod-like member 51 (billet), and the first mold 10 of the pair, and the second die 20, and a wedge 44. Press 40 includes a bed 43, an upper base plate 41 to reciprocate vertically, a lower base plate 42, the elastic member 45 and a (eg, a spring). Lower base plate 42 is vertically movably held on the bed 43 via the elastic member 45.
[0081]
　The first upper die 11 of the first mold 10 is fixed to the upper base plate 41, the first lower die 12 is fixed to the lower base plate 42. The second mold 20 is a movable state along a (horizontal direction in this configuration example) sandwiched direction perpendicular to the direction of the first mold 10 is retained in the lower base plate 42. The part of the bottom surface of the second die 20, and an inclined surface 20a, the height of the inclined surface 20a is higher as the distance from the first die 10. The wedge 44 extends in the vertical direction, the lower end of the wedge 44 is fixed to the bed 43. The upper surface of wedge 44 is an inclined surface 44a, the height of the inclined surface 44a is higher as the distance from the first die 10.
[0082]
　When adopting such a configuration example, the pinching step, the first upper die 11 with the descent of the upper base plate 41 is lowered (see FIG. 9A). Accordingly, the first die 10 of the pair, rod-like member 51 is sandwiched. In this case, the parting surface of the first upper mold 11 and the parting surface of the first lower mold 12 abuts further an upper base plate 41 in contact with the second die 20 is brought, scissors step is completed (see FIG. 9B ).
[0083]
　After sandwiching completed and further lowering the upper base plate 41, it shrinks the elastic member 45 (see FIG. 9C). Accordingly, the first upper die 11, a first lower die 12 and second die 20 is lowered. At that time, the inclined surface 20a of the second mold 20 is pressed on the inclined surface 44a of the wedge 44, (see arrow hatched in FIG. 9C) in which the second die 20 is moved to the horizontal direction. Thus, the second die 20 is pressed against the rod-shaped member 51, a portion of the rod 51 eccentrically. Thus employing a wedge mechanism, it is possible to operate the second die 20 in accordance with the reciprocating motion of the upper base plate 41.
[0084]
　In the configuration example using the above-described processing flow example and a wedge mechanism, when the scissors of the first mold 10 of a pair has been completed, it starts the eccentricity of the second die 20. In the method of manufacturing the forged crankshaft of the present embodiment, if after the nip by the first mold 10 of a pair has been completed, any time may be started eccentricity of the second die 20.
Industrial Applicability
[0085]
　The present invention can be effectively utilized in the production of forged crankshaft mounted in a reciprocating engine.
DESCRIPTION OF SYMBOLS
[0086]
　1 forged crankshaft
　10 first mold
　11 first upper die
　12 first lower die
　20 and the second die
　20a inclined surface
　40 presses
　41 the upper base plate
　42 below the base plate
　43 bed
　44 the wedge
　44a inclined surface
　45 the elastic member
　51 bar-like member
　51a first portion (arm portion
　corresponding) 51b second portion (pin portion
　corresponding) 52 wasteland
　A, A1 ~ A8 crank arm
　B burr
　J, J1 ~ J5 journal portion
　P, P1 ~ P4 pin
　Fr front portion
　Fl flange
　W, W1 ~ W8 counterweight section

The scope of the claims

[Requested item 1]Forging and a plurality of journal portion as a rotational center, and a plurality of pin portions eccentric to the plurality of journal portions, and a plurality of crank arm connecting the said plurality of journal portions of the plurality of pin portions a method of manufacturing a crank shaft,
　wherein the manufacturing method,
　by sandwiching the first region is a part of the length of the rod-like member by the first mold pair, the steps scissors holds the first portion,
　in a state in which the first part was held by the first mold includes an eccentric step of decentering the second portion of the rod-shaped member by a second die,
　said second portion includes a plurality of pin portion comprising at least one pin corresponding portion of the plurality of pins corresponding portion,
　the first site, of a plurality of arms corresponding portions serving as the plurality of crank arm portion, said pin as said second portion Touching section is a plurality of arms corresponding portion in contact is,
　the eccentric direction of the second die, the direction scissors by the first mold, and a respective perpendicular direction of the longitudinal direction of the bar-like member, the corresponding in the same direction as the eccentric direction of the pin portion is, the production method of the forged crankshaft to.
[Requested item 2]
　A method of manufacturing a forged crankshaft according to claim 1,
　wherein the first portion further comprises journals of the journal portion corresponding to a plurality of journal portions, said arm corresponding portion as the first portion in contact including a substantial portion, the production method of the forged crankshaft.
[Requested item 3]
　A method of manufacturing a forged crankshaft according to claim 1 or 2,
　wherein at least one of the plurality of crank arm is the arm part there weight having a counterweight portion,
　said first site, there the weight and an arm corresponding portion there weight becomes an arm portion, the production method of the forged crankshaft.