0001]The present invention relates to a front axle beam and a manufacturing method thereof.
BACKGROUND
[0002]Front axle beam (hereinafter may be referred to as "front axle") is primarily a vehicle (e.g. a truck or bus, etc. (however, two-wheeled vehicles are excluded)) front wheel mounted to support the vehicle body They are used to. The front axle, as a component for transmitting the load of the vehicle body to the left and right front wheels, and, as a structural safety components, is important. The front axle, by securing a front wheel of the steering performance while securing the wheel in position, responsible for the running stability. Further, during braking, the front axle is a transmission path for transmitting the braking forces of the wheels. In this way, the front axle, running property, a steering resistance, and strongly affect parts in braking performance. Since required high rigidity for the front axle, the front axle weight is greater. On the other hand, from the viewpoint of fuel efficiency, weight reduction of the front axle is required.
[0003]
　In general, for the running stability of the vehicle, heavy object is disposed in a low position of the vehicle height direction of the vehicle. That is, the position of the engine mounted on the front axle is preferably mounted on a lower vehicle height direction position. Kingpin mounting portion is provided at both ends of the front axle. It is attached underbody parts to the front wheels of the vehicle. Kingpin is inserted into a front wheel of the undercarriage parts through the kingpin mounting portion from the vehicle height direction improves side connecting the front axle and the front wheels. The front wheel is pivoted a king pin in the axial turn off the steering of the vehicle by the configuration. Because of this configuration, as shown in FIG. 2, front axle, for example, vehicle-widthwise center is low in vehicle height direction, the vehicle width direction end portion is higher in the vehicle height direction, a bow shape. The front axle cross-section is in the H-type, but is not produced by the universal rolling machine as H-section steel. Because the arcuate shape is can not be molded by a universal rolling mill.
[0004]
　Normally, the front axle is produced by die forging. For forging, as shown in FIG. 10, for example, the angle Q for demolding, the draft of Q 'is required. Therefore, the shape of the front axle is limited. As a result, improvement of the rigidity of the front axle is limited.
[0005]
　JP 2003-285771 (Patent Document 1) proposes a front axle which can reduce the aerodynamic resistance during vehicle travel. The invention described in Patent Document 1 is aimed at improving fuel economy by reducing the aerodynamic drag.
[0006]
　Also, it has been proposed also a method for manufacturing the front axle. JP 2009-106955 (Patent Document 2) discloses a manufacturing method of the axle beam with a pair of left and right spring seat. In this manufacturing method, press molding one of the spring seat in the first round of the pressing process, press-molding the other spring seat at the second pressing step.
[0007]
　One strategy lighter front axle, and to increase the rigidity of the front axle. If it is possible to increase the rigidity of the front axle, the same rigidity as the conventional, more or lighter front axle can be realized in a more compact front axle. Further, if it is possible to increase the rigidity of the front axle, the same size and the same weight as the conventional products, the front axle is possible to improve the various properties concerned. Therefore, new technology that can increase the rigidity of the front axle is required.
[0008]
　On the other hand, around the front axle, the moving parts of the engine and steering are arranged densely. Therefore, the front axle, is also required to fit into tight spaces so as not to interfere with these peripheral parts. Therefore, technology that can enhance the rigidity without increasing the size of the front axle, in particular sought.
CITATION
Patent Document
[0009]
Patent Document 1: JP 2003-285771 Patent Publication
Patent Document 2: JP 2009-106955 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　In such circumstances, one object of the present invention, the front axle beam capable of increasing its rigidity, and to provide its manufacturing method.
Means for Solving the Problems
[0011]
　Manufacturing method according to an embodiment of the present invention includes a web portion, a manufacturing method of the front axle beam with a beam portion of the H-shaped cross-section of which comprises a flange portion which is joined to the opposite ends of the web portion. Forming manufacturing method, in the transverse plane, and die forging material forged type paired the central axis of the web section to the boundary, and the web section, the thickest flange portion wall thickness of the portion joined to the web portion to. Further, in the cross section, the location and pressure from the extending outward of the web portion by the first mold to form a thick portion on the outside of the portion of the flange portion.
[0012]
　Front axle beam according to an embodiment of the present invention includes a web portion, a front axle beam with a beam portion of the H-shaped cross-section of which comprises a joint the flanges at both ends of the web portion. In the cross section, of the flange portion, the central region having a width 50% region of the web portion comprises a thin walled portion of the outer maximum thickness than the thickness of the central region of the flange portion.
The invention's effect
[0013]
　According to the present invention, the front axle beam is obtained with high rigidity. According to the production method of the present invention can be easily produced the front axle beam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
[1] Figure 1 is a perspective view schematically showing an example of a front axle of the first embodiment.
FIG. 2 is a diagram showing the front of the front axle as shown in FIG. 1 schematically.
FIG. 3 is a diagram showing the upper surface of the front axle as shown in FIG. 1 schematically.
[4] FIG. 4 is a diagram showing a cross section of the front axle as shown in FIG. 1 schematically.
[Figure 5A] Figure 5A is produced by the production method of the second embodiment is a perspective view schematically showing a part of an example of a forged product after burr vent.
[Figure 5B] Figure 5B is a diagram illustrating the forging of the cross section shown in FIG. 5A schematically.
[Figure 6A] Figure 6A is a cross-sectional view schematically showing a state before the start of deformation of an example of a reduction process.
[Figure 6B] Figure 6B is a cross-sectional view showing a state during deformation completion schematically an example shown in FIG. 6A.
[7] FIG. 7 is a diagram showing a sectional shape of the sample which is assumed in the examples.
[8] FIG. 8 is a diagram showing a method of testing assumed in the examples.
[9] FIG. 9 is a diagram schematically showing a cross section of the front axle of the embodiment.
FIG. 10 is a cross-sectional view of a conventional front axle is a diagram schematically illustrating.
DESCRIPTION OF THE INVENTION
[0015]
　As a result of intensive studies, the present inventors have found that to improve the rigidity of the front axle by devising the sectional shape of the front axle. In addition, it was found also method of manufacturing a highly rigid front axle. The present invention is based on this new finding.
[0016]
　Manufacturing method according to an embodiment of the present invention includes a web portion, a manufacturing method of the front axle beam with a beam portion of the H-shaped cross-section of which comprises a flange portion which is joined to the opposite ends of the web portion. Forming manufacturing method, in the transverse plane, and die forging material forged type paired the central axis of the web section to the boundary, and the web section, the thickest flange portion wall thickness of the portion joined to the web portion to. Further, in the cross section, the location and pressure from the extending outward of the web portion by the first mold to form a thick portion on the outside of the portion of the flange portion.
[0017]
　In the above manufacturing method, the portion joined to the web portion of the flange portion to pressure from the extending outward of the web portion by the first mold may be longer flange portion in said transverse plane.
[0018]
　In the above manufacturing method, in the transverse plane, sandwiching the web portion in the second mold, and supports the flange portion in the second mold, pressure from extending outwardly of the web portion of the portion by the first mold to, it is preferable.
[0019]
　In the above manufacturing method, when the pressure from the extending outward of the web portion of the point by a first mold, also reduction portion to become thick portion, it is preferable.
[0020]
　Front axle beam according to an embodiment of the present invention includes a web portion, a front axle beam with a beam portion of the H-shaped cross-section of which comprises a joint the flanges at both ends of the web portion. In the cross section, of the flange portion, the central region having a width 50% region of the web portion comprises a thin walled portion of the outer maximum thickness than the thickness of the central region of the flange portion.
[0021]
　Further, in another aspect, the manufacturing method according to an embodiment of the present invention is the beam part and the method for producing a front axle beam and two kingpin mounting portions provided respectively on both longitudinal ends of the beam portions . Beam portion includes a web portion extending in the longitudinal direction, a first flange portion projecting forward and backward from the upper end of the web portion, and a second flange portion which projects back and forth from the lower end of the web portion. Manufacturing method, a rough web portion comprising a web portion, a first coarse flange portion projecting forward and backward from the upper end of the rough web portion, a second coarse flange portion projecting forward and backward from the lower end of the rough web portion a first forging comprising, a die forging forming by die forging the steel material, by rolling the first forging from a first vertical forgings by at least one first mold , and a reduction step of forming a second forging comprising at least one coarse flange portion having a certain thickness change section. At least one of the first and second coarse flange portion of the first forging includes a deformable portion which is the thickness change section. The thickness of the deformable portion is the largest in the area in the vertical direction of the rough web portion. Thickness variation of the second forging includes a forward portion that from the end of the rough web portion projects forward, and a rear portion projecting rearwardly from the end portion. Each front portion and rear portion, includes a first portion and a distant second portion from the crude web portion than thick and the first portion than the first portion. The reduction step, by reduction of the area in the vertical direction of at least the coarse web portion in a first mold of the deformable portion to move the material in the area in front and behind the first forgings, thereby forming the thickness changing section.
[0022]
　In the above manufacturing method, the length of the thickness change portion in the longitudinal direction of the second forging may be greater than the length of the deformed portion in the longitudinal direction of the first forging.
[0023]
　In the above manufacturing method, reduction step is performed in a state sandwiched by the rough web portion of the first forging the first two second mold from the front and rear direction of the forged product, it is preferable.
[0024]
　In the above manufacturing method, both the first and second coarse flange portion of the first forging includes a deformable portion, in reduction step, the thickness changing portion is on both the first and second coarse flange portion is formed, it is preferable.
[0025]
　In the above manufacturing method, the reduction process, as well as pressure deformation portion, shaping and reduction portions other than the deformed portion, it is preferable.
[0026]
　Further, in another aspect, the front axle beam, according to an embodiment of the present invention is a front axle beam comprising a beam portion, and two kingpin mounting portions provided respectively on both longitudinal ends of the beam portions. Beam portion includes a web portion extending in the longitudinal direction, a first flange portion projecting forward and backward from the upper end of the web portion, and a second flange portion which projects back and forth from the lower end of the web portion. At least one of the first and second flange portions include a certain thickness change section. The thickness change section includes a forward portion that projects forwardly from the end of the web portion, and a rear portion projecting rearwardly from said end. Front portion and rear portion, respectively, comprises a first portion and a distant second portion from the web portion than thick and the first portion than the first portion.
[0027]
　Hereinafter, embodiments of the present invention will be described by way of example. The present invention is not limited to the examples described below.
[0028]
　In this specification, when referring to the direction of the members constituting the front axle and which, unless otherwise stated, it refers to a direction in a state of arranging the front axle in the direction of use. For example, the term vertical direction of the front axle, unless otherwise stated, refers to a vertical direction in a state of arranging the front axle in the direction of use. That is, the up and down direction, which is the vehicle height direction of the front axle. Similarly, the horizontal and longitudinal directions, means a direction in a state of arranging the front axle in the direction of use. That is, the horizontal direction is a vehicle width direction of the front axle. The front-rear direction, which is the vehicle length direction of the front axle. Here, the front axle is provided with a beam portion having a H-shaped cross section of the beam portion comprises a plate-shaped web portion, a plate-shaped flange portion which projects from both ends of the web portion. When placing the front axle in the direction of use, the beam portion is disposed in a horizontal direction. Furthermore, in cross-section of the front axle, the web portion extends in a vertical direction, a flange portion protruding in the longitudinal direction. Therefore, in the transverse plane of the front axle, the vertical direction is the same direction as the extending direction of the web portion, the front-rear direction is the same direction as the direction orthogonal to the extending direction of the web portion. Incidentally, the front and rear of the front axle, respectively, a front axle means in the same direction as the front and rear of the vehicle to be located. However, if the front axle is in the form of a symmetrical before and after the one direction and the front to the other direction as the rear. The intermediate products in the production of front axle when referring to the direction of the (first and second forgings, etc.) and members constituting it, unless otherwise noted, the same as the front axle is finished It refers to the direction.
[0029]
　(Manufacturing method of the front axle beam)
　the production method of the present embodiment, the beam portion and the method for producing a front axle and two kingpin mounting portions provided respectively on both longitudinal ends of the beam portion (front axle beam) it is. Beam portion includes a web portion extending in the longitudinal direction, a first flange portion projecting forward and backward from the upper end of the web portion, and a second flange portion which projects back and forth from the lower end of the web portion. That is, the manufacturing method of this embodiment includes a web portion, in the manufacturing method of the front axle (front axle beam) with a beam portion of H-shaped cross-section of which comprises a flange portion which is joined to the opposite ends of the web portion, the is there. This manufacturing method includes a die forging process and the reduction process described below in this order. In the present disclosure, means that simply integrated in the bonding, does not necessarily mean that joining by means of welding or fastening.
[0030]
　Die forging process, by die forging steel first forging (e.g., the first forging forging 201 of FIG. 5A) is a step of forming a. The first forging a rough web portion comprising a web portion, a first coarse flange portion projecting forward and backward from the upper end of the rough web portion, a second coarse projecting around the lower end of the rough web portion and a flange portion. Each of the first and second coarse flange portion, a portion serving as the first and second flange portions of the front axle.
[0031]
　At least one of the first and second coarse flange portion of the first forging comprises deforming portion to be a thickness change section described later. The thickness of the deformable portion is the largest in the region in the vertical direction of the rough web portion. That is, the deformable portion is in the vicinity of the rough web portion (vertical direction in the region of at least rough web portion), has a thick portion (the thick regions) than other portions. The thickness of the deformable portion, means thickness along the vertical direction of the first forging (length).
[0032]
　That is, in the manufacturing method of this embodiment, die-forging a material (steel) using a pair of forging die. Forging die are paired with the center line of the web portion (coarse web portion) to the boundary. This die forging, web portion (coarse web portion), the thickness of the portions joined to the web portion forms a thickest flange.
[0033]
　Usually, the first forged article obtained by the die forging process burrs are formed. Therefore, it may be carried out burr punching step between the die forging process and the reduction process. There is no limitation on the burr punching process may be applied to known methods. When performing burr punching step, the first forging burr has been removed, it is subjected to a reduction process.
[0034]
　Reduction step, at least by the one first mold by rolling the first forging the vertical direction of the first forging second forgings (e.g., forging of the second forging Figure 6A 202) is a step of forming a. The second forging comprises at least one coarse flange portion having a certain thickness changing portion (specific rough flange portion).
[0035]
　Thickness variation of the second forging includes a forward portion that projects forwardly from the end of the rough web portion and a rear portion projecting rearwardly from the end. Each front portion and rear portion, and a first portion and than thick and the first portion than the first portion away from the crude web portion a second portion to be described later. That is, the front portion and rear portion, respectively, includes a thickened portion formed at a position away from the crude web portion.
[0036]
　The reduction step, by reduction region (thick region) in the first mold in the vertical direction of at least rough web portion of the deformed portion of the first forging, the material in the said region the first It moved forward and backward forging, thereby forming a thickness change section.
[0037]
　There is no particular limitation on the first mold, as long as it can be deformed deformation portion in the thickness changing portion. One example first mold has a protrusion for moving press the thick region of the deformable portion.
[0038]
　In other words, in the manufacturing method of this embodiment, the pressure from the extending outward of the web portion of the portion joined to the web portion of the flange portion (rough flange portion) (crude web portion) by the first mold. Thereby forming a thick portion on the outside of the portion of the flange portion.
[0039]
　First and second forgings, containing the crude beam portion comprising a beam unit. Hereinafter, the longitudinal direction of the beam portion and the coarse beam portion, sometimes referred to as "longitudinal direction LD". Further, the front-rear direction of the front axle and forgings called "front-rear direction HD", their vertical may be referred to as "vertical direction VD."
[0040]
　Thickness change portion may be formed over the entire longitudinal direction LD of the coarse beam portion may be formed only on a part of the longitudinal direction LD of the coarse beam portion. Normally, the front axle has two spring mounting seat. The thickness change section may be formed on all or part of the region between the two spring mounting seat thereof. Deformable portion is formed corresponding to a portion where the thickness changing portion is formed position.
[0041]
　According to the above manufacturing method, can be formed thickness change portion having the above shape. As described later, by using the thickness change section, it is possible to enhance the rigidity without increasing the weight of the front axle.
[0042]
　In this specification, when referred to the inner and outer the flanges (or coarse flange portion), unless contrary to the context, refers to inner and outer in the vertical direction VD of the front axle or forging. If the flange portion projecting from the upper end of the web portion (or coarse web portion) (or coarse flange portion), the inner direction means downward, the outer direction means upward. If the flange portion projecting from the lower end of the web portion (or coarse web portion) (or coarse flange portion), the inner direction means upwards, the outward direction refers to lower.
[0043]
　The length of the thickness change section in the front-back direction HD of the second forging is greater than the length of the deformed portion in the longitudinal direction HD of the first forging. That is, when the deformable portion is deformed in the thickness changing portion length that they protrude from the crude web portion may be increased.
[0044]
　In other words, in the manufacturing method of this embodiment, the pressure from the extending outward of the web portion of the portion joined to the web portion of the flange portion (rough flange portion) (crude web portion) by the first mold. Thus, it may be longer flange portion.
[0045]
　Reduction step may be performed in a state sandwiched by the rough web portion of the first forging the first forging two second mold from the front and rear direction in HD.
[0046]
　That is, in the manufacturing method of this embodiment, sandwiched web portion (crude web portion) in the second mold support flanges (crude flange portion) in the second mold. In this state, it may be pressure from extending outwardly of the web portion of the portion joined to the web portion of the flange portion (rough flange portion) (crude web portion) by the first mold.
[0047]
　Both the first and second coarse flange portion of the first forging may include a deformed portion. In this case, in the reduction step, the thickness changing portion is formed in both the first and second coarse flange portion. Note that only one of the first and second coarse flange portion of the first forging may include a deformed portion. In this case, in the reduction step, only on one thickness changing portion of the first and second coarse flange portion is formed.
[0048]
　Typically, the shaping step is performed after the reduction process. The shaping step, the shape of the predetermined portion (e.g., a spring mounting seat) is trimmed. It may be carried out simultaneously shaping step and reduction step in the production method of the present embodiment. That is, in the reduction step, as well as reduction of the deformation portion may be shaped by rolling the portion other than the deformed portion. According to this configuration, it is possible to suppress the number of steps to a conventional manufacturing method is increased. In this case, the first mold may also serve as a mold shaping process.
[0049]
　That is, in the manufacturing method of this embodiment, when the pressure from the extending outward of the web portion of the portion joined to the web portion of the flange portion (rough flange portion) (crude web portion) by the first mold, thick place where it can be used as a part may also be under pressure.
[0050]
　(Front axle beam)
　front axle of the embodiment (front axle beam) can be produced by the production method of this embodiment. Matter manufacturing method described in this embodiment, it is possible to apply to the front axle of the present embodiment, there may be omitted the duplicate description. Also, matters described front axle of this embodiment is applicable to the production method of this embodiment. Incidentally, the front axle of this embodiment may be manufactured by a method other than the manufacturing method of this embodiment.
[0051]
　Front axle of this embodiment includes a web portion, and four flange portions joined to opposite ends of the web portion, the beam portion of the H-shaped cross-section of which comprises a. Comprising a thin portion in a central region disposed web portion side of the area of ​​the flange portion. The central region of the flange portion is a region from the end of the web portion side to 50% of the total width of the flange portion. The thickness of the thin portion is thinner than the maximum thickness of the outer central area of ​​the flange portion. In the present disclosure, means that simply integrated in the bonding, does not necessarily mean that joining by means of welding or fastening.
[0052]
　The front axle of this embodiment includes a beam portion, and two kingpin mounting portions provided on both ends in the longitudinal direction LD of the beam portion. Beam portion includes a web portion extending in the longitudinal direction LD, a first flange portion projecting forward and backward from the upper end of the web portion, and a second flange portion which projects back and forth from the lower end of the web portion. At least one of the first and second flange portions include a certain thickness change section. The thickness change section includes a forward portion projecting from the end of the web portion at the front, and a rear portion projecting rearwardly from the end. Front portion and rear portion, respectively, comprises a first portion and a distant second portion from the web portion than thick and the first portion than the first portion.
[0053]
　As described above, both the first and second flange portions may include a thickness change section. Alternatively, only the first flange portion may include a thickness change section, only the second flange portion may include a thickness change section.
[0054]
　In general, the bending stiffness can be assessed by the magnitude of the second moment, second moment sectional in proportion to the cube of the distance from the neutral line bending member becomes larger. In other words, it is effective in improving the stiffness to increase the cross-sectional area of ​​a portion away from the neutral line bending. The thickness change section includes a part of the thick at a position away from the web portion. In other words, the flange portion has a thin portion in the web portion side has a thick portion at a position away from the web portion. In this case, the cross section of the front axle, the center of gravity of the flange portion from the center of gravity of the beam portion relatively far position (a position farther than the conventional front axle) is arranged. Therefore, as compared with the flange portion of a conventional front axle extending in a plate shape, it is possible to increase the second moment of the flange portion. As a result, according to the front axle of the present embodiment, it is possible to increase the rigidity (flexural rigidity, and bending rigidity in the vertical direction VD in the front-rear direction HD) without increasing the mass. Furthermore, in comparison with the conventional flange portion, it is possible to increase the polar second moment of the flange portion. As a result, according to the front axle of the present embodiment, it is possible to increase the torsional rigidity without increasing the weight. In other words, it is possible to increase the rigidity per unit mass of the front axle (flexural and torsional rigidity). Further, by using the thickness change section, it is possible to achieve high rigidity without increasing the overall size of the front axle.
[0055]
　Usually, of the thickness variation of the surface, the outer surface of the vertical VD of the front axle, the distance from the web portion, inclined inwardly in the vertical direction VD after inclined outwardly in the vertical direction VD. Such thickness variation unit, when the flange portion is seen horizontally from the side which projects, with a portion to be a blind spot on the outer surface in the vertical direction VD. Portion serving as the blind spot for the inverse gradient in the mold forging step, it is difficult to form only at the die forging step thickness change section. Therefore, when forming the thickness changing section by a manufacturing method including a die forging process, it is necessary above reduction step. Conversely, the thickness changing portions can be easily formed by the die forging process and reduction step described above. Therefore, the front axle of this embodiment is also advantageous in terms of manufacturing.
[0056]
　We define the thickness of the flange portion at the junction of the flange portion and web portion, as follows. In cross-section of the beam portion, the base of the contour of the web portion has an arc rather than a right angle. In other words, there is a corner R. Of the flange portion, the center point of the thickness of a portion not in contact with the web portion of the web in the vicinity, determined on either side of the flange portion sandwiched between the web portion. A direction connecting the center points between the extending direction of the flange portion. The extending direction of the flange portion, the tangent of the corner R, the angle between the tangent of the contact is increased closer to the web portion center. A flange portion extending direction, the tangent of the corner R, the angle of the tangent contact point of the corner R of when it becomes 10 °, determined on either side of the flange portion sandwiched between the web portion. The straight line connecting the contact points regarded as the boundary of the flange portion and web portion. Evaluating the thickness of the flange portion on the basis of the boundary.
[0057]
　Here, the cross section of a conventional front axle 500 (cross section perpendicular to the longitudinal direction LD), shown in FIG. 10. By die forging, when manufacturing front axle, line by moving in the direction in which the flange portions 530a ~ 530d protrudes (longitudinal direction HD (direction orthogonal to the extending direction of the web portion 520)) mold (forging die) divide. Therefore, the flange portion 530a ~ 530d, are provided gradients for demolding. Figure 10 shows the angle Q, Q 'of the draft for stamping direction (front-rear direction HD). For this slope, the conventional flange portion 530a ~ 530d is thinner closer to its end. In other words, in the conventional front axle 500, the flange portion 530a ~ 530d is thicker closer to the center of the web portion 520. In contrast, the flange portion of the present embodiment has a thin portion in the web portion side has a thick portion at a position away from the web portion.
[0058]
　As described above, the thickness changing portion has at least a portion of the region between the two spring mounting seat may be formed in (some or all). For example, the thickness change section, 50% of the area between the two spring mounting seat (based on the length in the longitudinal direction LD) may be formed above.
[0059]
　(Manufacturing apparatus)
　In another aspect, the present invention relates to apparatus for manufacturing front axle. This manufacturing device comprises a mold described above to be used in the reduction step, and a mechanism for moving the mold as described above. The mechanism for moving the mold can be applied to mechanisms that have been used in such known pressing apparatus.
[0060]
　The following description with reference to the drawings exemplary embodiments of the present invention. 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. In the following description, it may be omitted from redundant explanation are denoted by the same reference numerals to like parts. Moreover, are all figures schematically shown below, may be omitted and unnecessary portions in the description.
[0061]
　(First Embodiment)
　In the first embodiment, an example of a front axle of the present invention. A perspective view of the front axle 100 of the first embodiment, shown in FIG. A front view of the from the front of the front axle 100 viewed horizontally front axle 100, shown in FIG. A top view of the front axle 100 shown in FIG. Furthermore, the cross-sectional view taken along the line IV-IV in FIG. 3, shown in FIG. 4. In Figure 4, it will not be hatched. The drawing described in these figures and the following, the front axle 100 (or first forging 201 and second forgings 202), the forward direction FWD, may indicate the vertical direction VD, and the front-rear direction HD is there. Similarly, the figures may indicate a longitudinal direction LD of the beam portion 110 (or coarse beam portion 210).
[0062]
　Referring to FIG. 1, the front axle (front axle beam) 100 includes a beam portion 110, and two kingpin mounting portion 150 provided on both ends in the longitudinal direction LD of the beam portion 110. The kingpin mounting portion 150, through hole kingpin is attached is formed. Normally, the front axle 100 has a generally symmetrical shape about a center in the vehicle width direction, and have a generally arcuate shape as a whole. As shown in FIG. 2, the kingpin mounting portion 150, the tire 1 is connected via a kingpin.
[0063]
　Beam unit 110 includes a web portion 120 extending in the longitudinal direction LD, a first flange portion 131 which projects forward and backward from the upper end of the web portion 120, a second flange portion which projects back and forth from the lower end of the web portion 120 and a 132. Each of the first and second flange portions 131 and 132, including the thickness changing portions 141 and 142. In another aspect, the beam portion 110 includes a web portion 120 and a flange portion 131 and 132 joined to both ends of the web portion has a cross-section of H-type.
[0064]
　As shown in FIG. 4, the thickness change section 141 includes a forward portion 141a that protrudes forward from an end portion of the web portion 120, and a rear portion 141b projecting rearwardly from the end of the web portion 120. Each front portion 141a and the rear portion 141b, includes a first portion P1 and a second portion P2. The second portion P2 (thickened portion), far from the web portion 120 than thick and the first portion P1 than the first portion P1 existing in the vicinity of the web portion.
[0065]
　Similarly, the thickness changing portion 142 includes a forward portion 142a that protrudes forward from an end portion of the web portion 120, and a rear portion 142b projecting rearwardly from the end of the web portion 120. Similar to the front portion 141a and the rear portion 141b, respectively front portion 142a and rear portion 142b, includes a first portion P1 and a second portion P2 (thickened portion).
[0066]
　The thickness of the thickness changing portions 141 and 142, it refers thickness along the vertical direction VD of the front axle 100 (length). Figure 4 shows the front portion 141a and a front portion 142a, the thickness D2 of the thicknesses D1 and a second portion P2 of the first portion P1. Incidentally, the thickness D1 of the first portion P1 and the thickness D2 of the second portion P2, is compared in a single forward portion or one of the rear portion.
[0067]
　In another aspect, the front axle 100 of the present embodiment can be interpreted as follows. Figure 9 shows a cross section of the beam portion 110 of the front axle 100 of the present embodiment corresponding to FIG. Beam portion 110 has a cross-section of H-type. Beam unit 110 includes a web portion 120, and a four flange portions 130a ~ 130d joined to both ends of the web portion 120. For example, a thin portion 130aa in the central region Aa disposed web portion 120 side of the area of ​​the flange portion 130a. Central area Aa of the flange portion 130a is a region from the end of the web portion 120 side up to 50% of the total width Wa of the flange portion 130a. The thickness of the thin portion 130aa ta is smaller than the maximum thickness tmax of the outer central area Aa of the flange portion 130a.
[0068]
　In FIGS. 1 to 4, although the thickness variation portion 141 and the thickness variation portion 142 indicates an example which is asymmetrical in the vertical direction VD, they may be symmetrical in the vertical direction VD. Entire front axle has a bow-type structure, moreover, although the torsional load is generated when the kingpin is loaded load back and forth due to the upward rotation center of the torsional load is applied to the front axle, for example, since not always match the web center of FIG. 4, there are cases where better to the vertical asymmetry becomes high rigidity. Further, in FIGS. 1 to 4, the thickness changing portions 141 and the thickness changing portion 142, respectively, is shown an example which is symmetrical in the longitudinal direction HD, they may be asymmetrical in the longitudinal direction HD .
[0069]
　Outer surface 141s in the vertical direction VD of the surface of the thickness change section 141, the distance from the web portion 120, inclined inwardly in the vertical direction VD after inclined outwardly in the vertical direction VD. Surface of the thickness change section 142 also has a similar shape. Such thickness variation section, when viewed horizontally from the side where the first flange portion 131 protrudes, with a portion to be a blind spot on the outer surface in the vertical direction VD. As described above, it is difficult to form a portion serving as the blind spot only by die forging process.
[0070]
　In the example shown in FIG. 4, the inner surface 141t of the vertical VD of the surface of the thickness change section 141 is inclined toward the outside in the vertical direction VD throughout. Inner surface of the thickness change section 142 is also inclined similarly. However, the inclination of their inner surfaces is not limited to the inclined shown in FIG.
[0071]
　Referring to FIG. 1, the first flange portion 131, two spring mounting seat 111 is formed. Two spring mounting seat 111 is disposed on the left and right symmetrical positions at a distance. Spring is arranged in the spring mounting seat 111, a vehicle body (including the engine) is mounted on the spring. In the first embodiment, a description is given of a case where the thickness changing portions 141 and 142 are formed in the region between the two spring mounting seat 111, they may be formed at other positions.
[0072]
　In the cross section shown in FIG. 4 has a boundary between the inner surface 141t and the web portion 120 of the surface of the thickness change section 141 rounded shape (R shape). 4, the boundary of the thickness change section 141 (first flange portion 131) and the web portion 120, the one end of the R-shaped (R put away), the surface 141t side two end (front portion 141a is a straight line connecting the end) at the end and the rear portion 141b in. Boundaries of thickness change section 142 (second flange portions 132) and the web portion 120 is similar.
[0073]
　(Second Embodiment)
　In the second embodiment, an example of producing a front axle 100 shown in FIGS. 1 to 4 will be described with reference to the drawings. This manufacturing method includes a die forging process and reduction process described below in this order. Die forging step and reduction step is a hot processing carried out by heating the processing target.
[0074]
　In die forging process to form a first forging by die forging steel. There is no limitation to the die forging step can be carried out by known die forging process. In the die forging process, usually, burrs are formed in the first forging. If the burr is formed in the first forging burr punching step is performed before the reduction step. There is no limitation on the burr punching process can be carried out by known burr punching process.
[0075]
　Figure 5A is a perspective view showing a part of a cross section of a first forging 201 after burr punching process is performed. The first forging 201 includes a coarse beam portion 210 as the beam portion 110. Crude beam portion 210 includes a coarse web portion 220 serving as the web portion 120, a first rough flange portion 231 which projects back and forth from the upper end of the rough web portion 220, and protrudes forward and backward from the lower end of the rough web portion 220 and a second coarse flange portion 232. The first coarse flange portion 231, the portion 211 comprising a spring mounting seat 111 is formed. In Figure 5A, it shows a burr line BL portion burrs are removed by a dotted line.
[0076]
　First coarse flange portion 231 includes a deformable portion 231a, second coarse flange portion 232 includes a deformable portion 232a. Each deformed portion 231a, and 232a is a portion which is the thickness changing portions 141 and 142. In the following, mainly described the shape of the deformable portion 231a, has a similar shape deformation portion 232a.
[0077]
　Section through the deformable portions 231a and 232a (the section perpendicular to the longitudinal direction LD), shown in Figure 5B. Referring to Figure 5B, the thickness of the deformed portion 231a is larger closer to the rough web portion 220. More specifically, so as to maximize the portion of the burr line BL shown in FIG. 5B, the thickness of the deformed portion 231a is increased toward the burr line BL from the end portion. That is, the thickness of the deformed portion 231a is maximum becomes a certain area in the vertical direction VD of the crude web portion 220. In another aspect, the thickness of the first and second coarse flange portions 231 and 232 (deformable portions 231a and 232a) is thickest at a point joined to the coarse web portion 220 (corresponding to the burr line BL). Therefore, the shape of the deformed portion 231a in the cross section of FIG. 5B is generally in Yamagata. To such a shape is to form a thickness changing portion material by moving the region (thick region) in the vicinity of the rough web portion 220 in the reduction step described below.
[0078]
　Die forging step, moving the first and second coarse flange portion 231 and the direction 232 protrudes (the direction orthogonal to the extending direction of the longitudinal HD (rough web portion 220)) to the mold (forging die) It is carried out by. Forging die is the center line of the rough web portion 220 (burr line BL) in pairs in the boundary. Therefore, the deformed portion 231a, is provided gradients for demolding. FIG 5B, showing the angles Q1 and Q2 of the surface of the slope of the deformation portion 231a for stamping direction (front-rear direction HD). For this inclination, deformation part 231a is thinner closer to its end.
[0079]
　Angle Q2 and inner surfaces of the deformed portion 231a of the front-rear direction HD forms may be angular for general stamping (such as in the range of 0 ° ~ 10 °). Angle Q1 formed between the outer surface and the longitudinal direction HD of the deformed portion 231a is greater than the angle for general demolding. Angle Q1, for example may be in the range of 10 ° ~ 60 °. Although the surface of the deformed portion 231a indicates an example is planar in Figure 5B, the surface may be a curved surface. Further, in FIG. 5B, although the front-rear direction center of the deformed portion 231a, and 232a (a region in the vertical direction VD of the crude web portion 220 of the deformation portion 231a and 232a) are exemplified a pointed shape projecting, longitudinal the thickness of the vicinity of center in the direction is not limited to this shape if a thicker than the front-rear direction outside. For example, the front-rear direction center to have a flat surface, may be in the form of trapezoidal.
[0080]
　Steel as a material for the die forging process typically has a shape suitable for die forging. Such steel can be formed by preforming a billet which is a starting material in the preforming step. That is, the steel material may be a preform. There is no limitation to the preforming step, it may be applied known preforming process. For example, pre-molding step, and the step of squeezing the billet may include bending beating process. Preforming step is usually hot working.
[0081]
　An example of a reduction process shown in the sectional view of FIG. 6A and 6B. The reduction step to form a second forgings 202 by rolling the first forging 201 in the vertical direction VD of the first forging 201 by at least one first mold 310. Here, the at least one first mold 310, refers to at least one of the upper and lower mold of the first mold 310.
[0082]
　In reduction step First, as shown in FIG. 6A, placing a first forging 201 between the first mold 310 and the first mold 310 of the upper downward. The first mold 310 has a convex portion 310a. At least one of the first mold 310 is moved in the vertical direction VD of the first forging 201.
[0083]
　As shown in FIG. 6A, reduction step may be carried out in a state sandwiched by the front-rear direction HD from the two second mold 320 of a coarse web portion 220 of the first forging 201 first forging 201 . In other words, it may be carried out reduction step in a state sandwiching the rough web portion 220 by the two second mold 320 in the direction perpendicular to the moving direction of the first mold 310. By fixing the forging 201 in the second mold 320, it can be carried out reduction process accurately. Furthermore, by fixing across the rough web portion 220 in the second mold 320, the coarse web portion 220 can be prevented from being deformed by the pressure process.
[0084]
　As shown in FIG. 6A, the second mold 320 is deformed portion may have the 231a and 232a inner surface and shaped to contact the rough web portion 220 of the surface of, if those Sessure the rough web portion 220 other parts (rough web portion 220 and the portion other than the portion abutting) of the second mold 320 may not be in contact with deformable portions 231a and 232a.
[0085]
　Next, as shown in FIG. 6B, rolling the first forging 201 lowers the first mold 310 of the upper. By reduction area in the vertical direction VD of the crude web portion 220 of the deformation portion 231a and 232a (the thick regions) and its vicinity in the first mold 310, the material in the said region the first forging 201 is moved forward and rearward of, thereby forming a thickness change section 141 and 142. The first mold 310 to have a convex portion 310a, tends to move the material. Furthermore, first mold 310 is because it has a thick region, it is possible to move large amounts of material.
[0086]
　In another aspect, FIG. 4, as shown in FIGS. 5B and 6B, the coarse flanges 231 and 232 (deformable portions 231a and 232a) of the crude web portion (corresponding to the burr line BL) the joined portion 220 of the web portion to reduction by the first mold 310 from the outside of the 220 in the extending direction (vertical direction VD). Thus, to form a thick portion on the outside of the portion of the flange portion 131 and 132 (second portion P2), the thin portion in the center region of the web portion 120 side of the flange portion 131 and 132 (first part P1 ) to form. The thickness of the thin portion is thinner than the maximum thickness of the thick portion.
[0087]
　Second forging 202 is thus obtained. Second forgings 202 includes a third coarse flange portion 241 having a thickness changing portion 141, and a fourth coarse flange portion 242 having a thickness changing portion 142.
[0088]
　By the above die forging process and reduction process, the second forging 202 having substantially the same outer front axle 100 is obtained. The resulting second forging 202 may be subjected to various processes as needed. Examples of these processes, the shaping process, drilling process, the heat treatment step, bend-up step, surface treatment step, and the like coating process. These steps can be carried out by known methods. In this way, the front axle 100 is manufactured. As described above, reduction step may also serve as the shaping step.
Example
[0089]
　Hereinafter, more detailed description of the examples the invention.
[0090]
　In this example, to evaluate the rigidity of the beam portion of the present embodiment has a thickness changing portion, the beam portion of the comparative example having no thickness change section and stiffness by simulation. In the simulation, as a model of the beam portion, the cross-sectional shape perpendicular to the longitudinal direction length constant is assumed to 100mm model. The physical properties of samples 1 and 2, assuming a Young's modulus and 210 GPa, and Poisson's ratio was assumed to 0.293. The simulation was carried out by the finite element method. Mass samples 1 and 2 were the same. That is, the vertical cross-sectional area in the longitudinal direction was the same in samples 1 and 2.
[0091]
　Sample 1 of the cross-sectional shape of the present embodiment, and FIG. 7 shows a sample 2 of the cross-sectional shape of comparative example. In cross-section (longitudinal direction LD in the cross section perpendicular) shown in FIG. 7, the cross section of Sample 1 and Sample 2 are and vertically symmetrical symmetrical. The flange portion of the sample 2, it was assumed that the projecting horizontally in the longitudinal direction HD from the upper and lower ends of the web portion. The angle of the draft of the sample 2 was assumed to 5 °.
[0092]
　As shown in FIG. 7, assuming X and Y coordinates as the origin centroid CT of each sample in the cross section of FIG. X-axis of the X-coordinate is parallel to the longitudinal direction HD of the beam portion, Y-axis of the Y coordinate is parallel to the vertical direction VD of the beam portion. A region X and Y coordinates are both positive, namely one quarter of the cross section was determined centroid. Position of the center of gravity CG1 of samples 1, and shows the position of the center of gravity CG2 of the sample 2 in Fig. These coordinates (unit: mm) are shown below.
The center of gravity of the sample 1 CG1: (X, Y) = (21.629,23.507)
Sample 2 of the center of gravity CG2: (X, Y) = (21.121,19.812)
[0093]
　As mentioned above, X and Y coordinates of the center of gravity CG1 of the sample 1 of this embodiment was greater than those of the center of gravity CG2 of sample 2 of Comparative Example. By this X-coordinate and Y-coordinate is large, enabling increased polar second moment against torsion and increase the second moment, also the increase of the moment of inertia with respect to bending deformation by the vertical load is light weight relative to bending deformation by longitudinal load , an effect that can be obtained.
[0094]
　For Samples 1 and 2, the rigidity on the basis of the deformation amount when a load is applied as shown in FIG. 8, it was obtained by simulation. Specifically, the one end face of one of the two end faces restrained, the load is applied in a direction indicated by an arrow shown in FIG. 8 on the other end face. From deformation amount of the position of the load is applied to determine the stiffness. Note the amount of deformation and stiffness is inversely proportional. The load of the bending back and forth shown in FIG. 8, was obtained the rigidity in the front-rear direction. The upper and lower bending load of 8 to determine the stiffness in the vertical direction. The load of the rotation torque shown in FIG. 8, was determined torsional rigidity. The evaluation results are shown in Table 1.
[0095]
[Table 1]

[0096]
　As shown in Table 1, longitudinal rigidity and torsional rigidity of the sample 1 of the present embodiment was higher than those of sample 2 of Comparative Example 2. Further, the vertical stiffness of the sample 1 was significantly higher than that of sample 2.
[0097]
　As is apparent from the above results, by using a beam portion having a thickness variation of the present embodiment, the mass is the same rigidity higher front axle is obtained. This indicates that you can weight the front axle without reducing a predetermined rigidity. This further shows that there is a possibility of realizing the conventional and more rigid comparable conventional products equal to or less than the size.
Industrial Applicability
[0098]
　The present invention can be used in the front axle beam.
DESCRIPTION OF SYMBOLS
[0099]
　100: front axle (front axle
　beam) 110: beam portion
　111: spring mounting seat
　120: web portion
　131: first flange portion
　132: second flange portion
　141, 142: the thickness changing portions
　141a, 142a: front portion
　141b, 142b: rear portion
　150: kingpin mounting portion
　201: first forging
　202: second forging
　210: crude beam part
　220: crude web portion
　231: first coarse flange portion
　232: second coarse flange part
　231a, 232a: deformation portion
　310: first mold
　320: second mold
　P1: first partial
　P2: second partial
　LD: longitudinal
　HD: longitudinal direction
　VD: vertical direction

WE CLAIM

And the web portion, the method of manufacturing a front axle beam with a beam portion of the H-shaped cross-section of which comprises a flange portion which is joined to the opposite ends of the web portion,
　in the cross section, the center of the web portion axis and die forging material forged type paired to the boundary of the said web portion, the thickness of the portions joined to the web portion forms a thickest said flange portion,
　in the cross section, the portion the the first die and pressure from the extending outward of said web portion, forming a thick portion on the outside of the portion of the flange portion, a method of producing a front axle beam.
[Requested item 2]
　The portion joined to the web portion of the flange portion to pressure from the extending outward of the web portion by the first mold, to prolong the flange portion in the cross section, the front axle beam according to claim 1 the method of production.
[Requested item 3]
　In the cross section, sandwiching said web portion in the second die, said supporting the flange portion in the second mold, for rolling the extending direction outer side of the web portion of the portion by the first mold the method of manufacturing a front axle beam according to claim 1 or claim 2.
[Requested item 4]
　When pressure from the extending outward of said web portion of said portion by said first die, said to be reduction portion to become thick portion, the front axle according to any one of claims 1 to 3 method for producing a beam.
[Requested item 5]
　And the web portion, said a front axle beam comprising a flange portion which is joined at both ends, the beam portion of the H-shaped cross-section of which comprises a web portion,
　in the cross section, of the flange portion, the web portion in the central region of width 50% area of the side, comprising the thin walled portion of the outer maximum thickness than the thickness of the central region of the flange portion, the front axle beam.