Method for manufacturing a vehicle suspension arm and vehicle suspension arm

Abstract

Provided is a manufacturing method for a vehicle suspension arm that can satisfy the quality (coaxiality and circularity) of a pair of through holes, and a vehicle suspension arm. In the manufacturing method for the vehicle suspension arm, a stage bending process has a first bending process and a second bending process. In the first bending process, a punch 106 (first punch) is used to press a portion of a workpiece W that constitutes a base portion 23 of a main body portion 20 and a portion that constitutes a first link portion 31, and pre-bending is performed. After the first bending process, the second bending process releases the press of the first punch on the portion that constitutes the first link portion, and a punch 108 (second punch) is used to press the portion of the base portion 23 that constitutes the main body portion 20, while bending is performed along a bend line 72 formed in the first bending process.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a vehicle suspension arm and the vehicle suspension arm itself. Background Technology

[0002] A vehicle suspension arm is used to connect the vehicle body and the wheels. The vehicle suspension arm has through holes facing each other at the connecting portion at its longitudinally positioned end (see Patent Documents 1 and 2). The through holes are formed by flanging and have cylindrical flanges.

[0003] Patent document 1 discloses a manufacturing process in which a through hole is formed by flanging after the main body of the forming arm is formed when manufacturing a suspension arm for a vehicle.

[0004] Patent document 2 discloses a processing method for forming an arm using a progressive method. In this process, a through hole is pre-formed by flanging a flat base material, and then the workpiece is bent.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-39716

[0008] Patent Document 2: International Publication No. 2020 / 116320 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, in the case of a machining process using a cam mechanism, as in Patent Document 1, there is a problem of increased mold structure complexity. Furthermore, as the product width between the connecting parts forming the through hole narrows, it restricts the mold support structure during flanging. Therefore, problems arise such as mold die deformation or increased maintenance operations. Moreover, depending on the product shape, the space for supporting the flanging die is restricted, making the die structure itself impossible to establish.

[0011] In the case of a progressive machining process as described in Patent Document 2, when the product width between the connecting parts is narrow, the shape of the feed stack connecting the base material and the arm component becomes thinner. Therefore, the cutting edge of the punch that cuts the arm component from the base material becomes thinner. This causes problems with the durability of the punch, making it unsuitable for stable manufacturing. Consequently, it is unsuitable for mass production of the arm component.

[0012] In view of this, the object of the present invention is to provide a technique for satisfying the quality (coaxiality and roundness) of a pair of through holes in a vehicle suspension arm manufactured by forming at least a pair of through holes with cylindrical flanges by flanging a workpiece and performing staged bending on the workpiece.

[0013] Problem Solving Methods

[0014] One embodiment of the present invention is a method for manufacturing a vehicle suspension arm, wherein at least a pair of through holes having cylindrical flanges rising from a plate surface are formed in a workpiece by flanging, and a phased bending process is performed on the workpiece. The vehicle suspension arm has a hollow main body and connecting portions opposite to each other with the axes of the pair of through holes aligned. The main body has two opposing sidewalls and a base connecting the two sidewalls to each other, and extends in one direction. The connecting portions extend from the ends of the two sidewalls in the one direction along the one direction and are spaced apart and opposite to each other. The phased bending process includes a first bending step and a second bending step. In the first bending step, a first punch presses the portion of the workpiece constituting the base of the main body and the portion constituting the connecting portion, while pre-bending. The second bending process continues the first bending process. While releasing the pressure of the first punch on the part constituting the connecting portion, the second punch presses on the part constituting the base portion of the main body portion and bends along the crease formed in the first bending process.

[0015] Another embodiment of the present invention is a vehicle suspension arm manufactured using the above-described method for manufacturing vehicle suspension arms.

[0016] The effects of the invention

[0017] According to the present invention, in a vehicle suspension arm manufactured by forming at least one pair of through holes with cylindrical flanges using a flanging process on a workpiece, and by performing a phased bending process on the workpiece, the quality (coaxiality and roundness) of the pair of through holes can be satisfied. Even if the product width of the connecting part is narrow and it is difficult to form the product shape of the through holes using a cam mechanism (mold), vehicle suspension arms that satisfy the quality (coaxiality and roundness) of the pair of through holes can be mass-produced. Attached Figure Description

[0018] Figure 1 (A) Figure 1 (B) and Figure 1 (C) is a perspective view, front view and top view of a vehicle suspension arm according to an embodiment.

[0019] Figure 2 (A) and Figure 2 (B) is along Figure 1 (B) Cross-sectional view of line 2A-2A, and along Figure 1 (B) Cross-sectional view of line 2B-2B.

[0020] Figure 3 (A) Figure 3 (B) and Figure 3 (C) is an explanatory diagram used to illustrate the problem of achieving arm weight reduction by utilizing the bending shape of the suspension arm for a vehicle.

[0021] Figure 4 A diagram showing the workpiece in the blanking process.

[0022] Figure 5 (A) is a drawing showing the workpiece in the flange bending process. Figure 5 (B) is along Figure 5 (A) View of line 5B Figure 5 (C) is along Figure 5 (A) The cross section of line 5C-5C represents the cross section of the flange bending process.

[0023] Figure 6 A diagram showing the workpiece in the trimming process.

[0024] Figure 7 (A) is a drawing showing the workpiece in the flanging process. Figure 7 (B) is along Figure 7 (A) shows the cross-section of line 7B-7B in the flanging process. Figure 7 (C) is along Figure 7 (A) shows the cross-section of the 7C-7C line, which is a cross-sectional view of the flanging process.

[0025] Figure 8 (A) is a drawing showing the workpiece in the first bending process. Figure 8 (B) is along Figure 8 (A) shows the cross-section of line 8B-8B in the first bending process. Figure 8 (C) is along Figure 8 (A) shows the cross-section of the 8C-8C line, which represents the cross-section of the first bending process.

[0026] Figure 9 (A) is a drawing showing the workpiece in the second bending process. Figure 9 (B) is along Figure 9 (A) shows the cross-section of line 9B-9B in the second bending process. Figure 9 (C) is along Figure 9 (A) shows the cross-section of the 9C-9C line, which represents the cross-section of the second bending process.

[0027] Figure 10 (A) is a drawing showing the workpiece in the third bending process. Figure 10 (B) is along Figure 10 (A) shows the cross-section of line 10B-10B in the third bending process. Figure 10 (C) is along Figure 10 (A) shows the cross-section of the 10C-10C line, which is the cross-sectional view of the third bending process.

[0028] Figure 11 (A) is a diagram showing the workpiece in the shaping process. Figure 11 (B) is along Figure 11 (A) shows a cross-sectional view of the shaping process along line 11B-11B. Figure 11 (C) is along Figure 11 (A) The cross section of line 11C-11C represents the cross section of the shaping process.

[0029] Figure 12 A diagram showing the workpiece in the cam punching process.

[0030] Figure 13 (A) to (D) are cross-sectional views showing examples of deformation of the punch and die used in the second bending process.

[0031] Explanation of symbols in the attached drawings

[0032] 10 A vehicle suspension, 20 Main body, 21, 22 Side walls, 23 Base, 24, 25 Inward ribs, 26 Clearance, 31 First connecting part (connecting part), 32 Second connecting part, 41 First flat plate part, 42 Second flat plate part, 51 First through hole (through hole), 51a Flange, 51b Bottom hole, 52 Second through hole, 60a Suspension arm, 60b Suspension arm, 60c Suspension arm, 72 Crease formed in the first bending process, 101 Die used in the flange bending process, 10 2. Punch used in the flange bending process; 103. Die used in the flanging process; 104. Punch used in the flanging process; 105. Die used in the first bending process; 106. Punch used in the first bending process (first punch); 107. Die used in the second bending process; 108. Punch used in the second bending process (second punch); 109. Die used in the third bending process; 110. Punch used in the third bending process (third punch); W. Workpiece Detailed Implementation

[0033] Hereinafter, the methods for carrying out the present invention will be described in detail with reference to the accompanying drawings. The embodiments shown herein are examples for embodying the technical concept of the present invention and do not constitute a limitation thereof. Therefore, all other implementable methods, embodiments, and techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included within the scope and spirit of the present invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0034] Furthermore, for ease of illustration and understanding, the accompanying drawings illustrate changes from the actual object to appropriate scales, aspect ratios, shapes, etc., but these are merely examples and do not limit the interpretation of the present invention.

[0035] In addition, this specification may use ordinal numbers such as "first" and "second". However, unless otherwise specified, these ordinal numbers are added to identify the constituent elements during the description, and are not used to specify a quantity or order.

[0036] Embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in this embodiment, the surface on which the workpiece is disposed is designated as the XY plane, the direction in which the flat plate extends is designated as the X direction (first direction), the direction orthogonal to the X direction in the disposal surface is designated as the Y direction (second direction), and the direction orthogonal to the XY plane is designated as the Z direction (third direction).

[0037] Figure 1 (A) Figure 1 (B) and Figure 1 (C) is a perspective view, front view and top view of the vehicle suspension arm 10 according to the embodiment. Figure 2 (A) and Figure 2 (B) is along Figure 1 (B) Cross-sectional view of line 2A-2A, and along Figure 1 (B) Cross-sectional view of line 2B-2B.

[0038] The vehicle suspension arm 10 in the embodiment is, for example, used in a multi-link suspension. In the following description, the vehicle suspension arm 10 will also be simply referred to as "suspension arm 10".

[0039] like Figure 1 (A) Figure 1 (B) Figure 1 (C) Figure 2 (A) and Figure 2As shown in (B), generally speaking, the suspension arm 10 is formed by performing a phased bending process on the workpiece after forming at least a pair of through holes 51 with cylindrical flanges 51a through a flanging process. The suspension arm 10 has a hollow main body 20 and connecting portions 31 that are opposite to each other in a state where the axes of the pair of through holes 51 are aligned. The main body 20 has two side walls 21, 22 that are opposite to each other and a base 23 that connects the two side walls 21, 22 to each other, and extends in one direction. The connecting portions 31 extend from the ends of the two side walls 21, 22 in one direction and are spaced apart from each other. In the embodiment, one direction corresponds to the X direction (first direction). Hereinafter, a detailed description will be given.

[0040] like Figure 1 (A) Figure 1 (B) and Figure 1 As shown in (C), the suspension arm 10 has a main body 20, a first connecting part 31 (equivalent to a connecting part) provided at the left end of the main body 20 in the X direction view, and a second connecting part 32 provided at the right end of the main body 20 in the X direction view.

[0041] like Figure 2 As shown in (A), the main body 20 has two sidewalls 21, 22 facing each other and a base 23 connecting the two sidewalls 21, 22. The main body 20 also has inward ribs 24, 25 in a cross section orthogonal to the X direction, where the end faces of the two sidewalls 21, 22 face each other. The end faces of the inward ribs 24, 25 face each other with a gap 26 between them. Thus, the main body 20 has a hollow shape with an open surface through the gap 26.

[0042] The first connecting portion 31 is composed of two first flat plate portions 41 facing each other along the Y direction. The two first flat plate portions 41 extend from the two side walls 21, 22 along the X direction. Figure 1 (B) and Figure 1 The left end of (C) extends along the X direction. The two first plate portions 41 are not connected by a component like the base 23 of the main body portion 20, but are spaced apart and opposite each other. Figure 2 As shown in (B), two first flat plate portions 41 have first through holes 51 (equivalent to through holes) formed at opposite positions along the Y direction. The first through holes 51 are formed by flanging and have cylindrical flanges 51a. A bushing is pressed into the first through holes 51 and connected to a shaft component (not shown) protruding from the side of the vehicle body via an elastic material such as rubber.

[0043] The second connecting portion 32 is the same as the first connecting portion 31, and is composed of two second flat plate portions 42 facing each other along the Y direction. The two second flat plate portions 42 extend from the two side walls 21, 22 along the X direction. Figure 1 (B) and Figure 1 The right end of (C) extends along the X direction. The two second plate portions 42 are not connected by a component like the base 23 of the main body portion 20, but are spaced apart and opposite to each other. The two second plate portions 42 have second through holes 52 formed at opposite positions along the Y direction. The second through holes 52 are formed by punching using a cam mechanism (die). The diameter of the second through hole 52 is smaller than the diameter of the first through hole 51. A bolt (not shown) from the wheel side is inserted into the second through hole 52 and connected to the wheel (not shown) by a nut (not shown).

[0044] Figure 3 (A) Figure 3 (B) and Figure 3 (C) is an explanatory diagram used to illustrate the problem of achieving arm weight reduction by utilizing the bending shape of the suspension arm for a vehicle.

[0045] like Figure 3 As shown in (C), when the suspension arm 60c is viewed from the front, the upper and lower parts of the main body 20 are not curved and are straight along the X direction. The dimension between the upper and lower parts of the main body 20 and the line segments (e.g., Lc described later) on the surfaces of the side walls 21 and 22 along the X direction is constant. In this configuration, the axis Lc connecting the center of the first through hole 51 and the center of the second through hole 52 is located at the center of the main body 20 in the Z direction.

[0046] like Figure 3 As shown in (B), when the suspension arm 60b is viewed from the front, the base 23 of the main body 20 is not curved and has a straight shape along the X direction. On the other hand, in the sidewalls 21 and 22, the ends opposite to the base 23 (above the inward ribs 24 and 25) have a curved shape (concave shape) whose dimensions with respect to the line segments (e.g., Lb described later) along the X direction on the surfaces of the sidewalls 21 and 22 gradually increase towards the ends in the X direction. In this case, the axis Lb connecting the center of the first through hole 51 and the center of the second through hole 52 is located near the upper part of the main body 20 in the Z direction. Figure 3 (B) The suspension arm 60b shown has a bending shape that is more... Figure 3 The suspension arm 60c shown in (C) is lighter.

[0047] like Figure 3As shown in (A), when the suspension arm 60a is viewed from the front, the base 23 of the main body 20 has a curved shape (convex shape) with the dimension between it and the line segment (e.g., La, described later) along the X direction on the surface of the sidewalls 21, 22, gradually increasing with the end facing the X direction. In the sidewalls 21, 22, the end opposite to the base 23 (the upper surface of the inward ribs 24, 25) has a curved shape (concave shape) with the dimension between it and the line segment (e.g., La, described later) along the X direction on the surface of the sidewalls 21, 22, gradually increasing with the end facing the X direction. In this configuration, the axis La connecting the center of the first through hole 51 and the center of the second through hole 52 is located at the center of the main body 20 in the Z direction. Figure 3 (A) The suspension arm 60a shown has a bending shape that is more than... Figure 3 (B) The suspension arm 60b shown is even lighter.

[0048] Next, the manufacturing method of the suspension arm 10 will be described. Furthermore, of the two surfaces in the thickness direction of the workpiece W, the surface forming the outer side of the suspension arm 10 is referred to as the surface, and the surface forming the inner side of the suspension arm 10 is referred to as the back side. As used in this specification, the term "plate surface" refers to the surface or back side in the thickness direction of the workpiece W.

[0049] Figure 4 This is a diagram showing the workpiece W in the blanking process. The front side of the workpiece W in the diagram is the back side.

[0050] There are no special restrictions on the material of the workpiece W, but high-tensile steel sheet with strength and light weight is preferred. During the blanking process, the machining datum (e.g., datum surface, datum hole, positioning hole, etc.) is determined. Furthermore, the outline is determined, and the cutting edges of the inward ribs 24 and 25 are determined. In addition, depending on the product shape, all cutting edges may be determined.

[0051] Figure 5 (A) is a diagram showing the workpiece W in the flange bending process. Figure 5 (B) is along Figure 5 (A) View of line 5B Figure 5 (C) is along Figure 5 (A) The cross section of line 5C-5C represents the cross section of the flange bending process.

[0052] In the flange bending process (equivalent to the bending into curvature process and the rib bending process), the curvature surface (the part constituting the base 23 of the main body 20) and the inward ribs 24 and 25 are pre-bent. In order to improve the positional accuracy of the first through hole 51 formed by the flanging process, before machining the bottom hole for the flanging process, the curvature surface is bent into a curvature that matches the bending shape of the base 23 (see reference). Figure 5(B)). Furthermore, ribs are formed in the third bending process described later to maintain the necessary punch width. These ribs constitute inward ribs 24 and 25. (See below) Figure 5 As shown in (C), the workpiece W is stamped using a die 101 and a punch 102, bending the portions forming the inward ribs 24 and 25. At this time, the surface side of the workpiece W is placed on the die 101, and stamping is performed on the back side by the punch 102. The inward ribs 24 and 25 are bent toward the back side of the workpiece W.

[0053] Figure 6 A diagram showing the workpiece W in the trimming process.

[0054] In the trimming process, trimming to form the product outline and machining of the bottom hole 51b for flanging are performed. To prevent changes in the shape of the outline during flanging, trimming and machining of the bottom hole 51b are performed simultaneously. Figure 6 The symbol 71 in the figure is a positioning hole used to position the workpiece W.

[0055] Figure 7 (A) is a diagram showing the workpiece W in the flanging process. Figure 7 (B) is along Figure 7 (A) shows the cross-section of line 7B-7B in the flanging process. Figure 7 (C) is along Figure 7 (A) shows the cross-section of the 7C-7C line, which is a cross-sectional view of the flanging process.

[0056] In the flanging process, a pair of first through holes 51 with cylindrical flanges 51a rising from the plate surface are formed on the workpiece W by flanging. To improve the positional accuracy of the first through holes 51, all the first through holes 51 (two in this embodiment) are formed simultaneously by flanging. Figure 7 (B) and Figure 7 As shown in (C), the workpiece W is stamped using a die 103 and a punch 104, forming a pair of first through holes 51 while clamping the portion constituting the main body 20. At this time, the portion constituting the main body 20 of the workpiece W is clamped by contacting the die 103 on the back side and the punch 104 on the surface side (see reference). Figure 7 (B)). The protrusion of the punch 104 is pressed into the bottom hole 51b from the surface side to form the first through hole 51 (see reference). Figure 7 (C)). Through the flanging process, the cylindrical flange 51a stands up from the plate surface of the workpiece W, that is, from the back side.

[0057] Figure 8 (A) is a diagram showing the workpiece W in the first bending process. Figure 8 (B) is along Figure 8(A) shows the cross-section of line 8B-8B in the first bending process. Figure 8 (C) is along Figure 8 (A) shows the cross-section of the 8C-8C line, which represents the cross-section of the first bending process.

[0058] In the first bending process, the punch 106 (equivalent to the first punch) presses down on the portion of the workpiece W that constitutes the base 23 of the main body 20 and the portion that constitutes the first connecting portion 31, while simultaneously performing pre-bending. There is no particular limitation on the bending angle; for example, it can be between 20 and 50 degrees. Figure 8 (B) and Figure 8 As shown in (C), the workpiece W is stamped using a die 105 and a punch 106. The punch 106 presses down on the portion constituting the base 23 of the main body 20 and the portion constituting the first connecting portion 31, while simultaneously pressing down on the workpiece W in conjunction with the die 105. The portion constituting the base 23 of the main body 20 and the portion constituting the first connecting portion 31 of the workpiece W contact the punch 106 on the back side and contact the die 105 on the surface. According to this first bending process, a crease 72 (see reference) can be formed while maintaining the coaxiality and roundness of the first through hole 51. Figure 8 (A)).

[0059] The pre-bending in the first bending process is performed by pressing the two side walls 21 and 22 that make up the main body 20 together with the punch 106 (see reference). Figure 8 (B)). The portions forming the two sidewalls 21, 22 contact the punch 106 on the back and the die 105 on the surface. Thus, the crease 72 can be formed correctly.

[0060] The portion constituting the first connecting part 31 includes the plate surface surrounding the raised flange 51a. The pre-bending in the first bending process is performed by pressing the plate surface surrounding the flange 51a with the punch 106 (see reference). Figure 8 (C)). The plate surface around the flange 51a contacts the punch 106 on the back side and the die 105 on the surface. Thus, the crease 72 can be formed while maintaining the coaxiality and roundness of the first through hole 51 more accurately.

[0061] Figure 9 (A) is a diagram showing the workpiece W in the second bending process. Figure 9 (B) is along Figure 9 (A) shows the cross-section of line 9B-9B in the second bending process. Figure 9 (C) is along Figure 9 (A) shows the cross-section of the 9C-9C line, which represents the cross-section of the second bending process.

[0062] After the first bending process, a second bending process is performed. In the second bending process, the pressure of the punch 106 (first punch) on the portion constituting the first connecting portion 31 is released, while the portion constituting the base 23 of the main body portion 20 is pressed by the punch 108 (equivalent to the second punch), and simultaneously bent along the crease formed in the first bending process. There is no particular limitation on the bending angle; for example, it is 50 degrees to less than 90 degrees. Figure 9 (B) and Figure 9 As shown in (C), the workpiece W is stamped using a die 107 and a punch 108. Instead of pressing the portion forming the first connecting portion 31, the punch 108 presses the portion forming the base 23 of the main body portion 20, while simultaneously pressing the workpiece W in conjunction with the die 107. The portion of the workpiece W forming the base 23 of the main body portion 20 contacts the punch 108 on its back side and the die 107 on its surface. The front end of the punch 108 has an R (arc) shape formed by the curved surface (base 23 of the main body portion 20) and the side walls 21, 22. According to this second bending process, portions of the two first flat plate portions 41 forming the first connecting portion 31 can be bent while maintaining the coaxiality and roundness of the first through hole 51.

[0063] In this specification, the phrase "bending along the crease 72 formed in the first bending process" for the second bending process does not refer only to bending from the crease 72. Bending from the crease 72 by moving a small distance away from it, or bending along a bending line set parallel or substantially parallel to the crease 72, should also be understood as included in "bending along the crease 72 formed in the first bending process".

[0064] Figure 10 (A) is a diagram showing the workpiece W in the third bending process. Figure 10 (B) is along Figure 10 (A) shows the cross-section of line 10B-10B in the third bending process. Figure 10 (C) is along Figure 10 (A) shows the cross-section of the 10C-10C line, which is the cross-sectional view of the third bending process.

[0065] After the second bending process, the third bending process is performed. In the third bending process, the punch 106 (first punch) is released. for While the portion constituting the first connecting part 31 is pressed, it is bent until the portion constituting the base 23 of the main body 20 is pressed by the punch 110 (equivalent to the third punch), causing the portions constituting the two side walls 21, 22 to face each other, and the axes of the pair of first through holes 51 of the first connecting part 31 to be aligned. The bending angle is 90 degrees. Figure 10 (B) and Figure 10As shown in (C), the workpiece W is stamped using a die 109 and a punch 110. The punch 110 passes through the gap 26 between the inward ribs 24 and 25, pressing down on the portion of the base 23 constituting the main body 20, while simultaneously pressing down on the workpiece W in conjunction with the die 109. The portion of the workpiece W constituting the base 23 of the main body 20 contacts the punch 110 on its back side and the die 109 on its surface. By pressing the workpiece W into the die 109, the two sidewalls 21 and 22 of the main body 20 are bent at 90 degrees relative to the base 23, thereby causing the two first flat plate portions 41 of the first connecting portion 31 to face each other parallel to each other.

[0066] Figure 11 (A) is a diagram showing the workpiece W in the shaping process. Figure 11 (B) is along Figure 11 (A) shows a cross-sectional view of the shaping process along line 11B-11B. Figure 11 (C) is along Figure 11 (A) The cross section of line 11C-11C represents the cross section of the shaping process.

[0067] In the shaping process, the product width is corrected and the inward ribs 24 and 25 are formed. For example... Figure 11 (B) and Figure 11 As shown in (C), the workpiece W is stamped using dies 111 and 112. To avoid excessive bending, the protrusion 113 of die 111 is inserted into and supported in the gap 26 between the inward ribs 24 and 25, while the workpiece W is formed by pressure from the outer periphery to the inner periphery. By pressing the two sidewalls 21 and 22, the product width is corrected, and the two first flat portions 41 of the first connecting portion 31 are corrected to be parallel. Through a shaping process, a hollow shape with open surfaces facing each other across the gap 26 is formed. By setting the protrusion 113 of die 111 to have a distance equal to or greater than that of the gap 26 extending in the X direction, a hollow shape with open surfaces is formed from one end to the other along the X direction.

[0068] Figure 12 A diagram showing the workpiece W in the cam punching process.

[0069] In the cam punching process, second through holes 52 are formed on the two second flat plates 42 of the second connecting part 32 at opposite positions along the Y direction. The workpiece W is positioned by locating pins. The second through holes 52 are formed by the cam mechanism (die) and by punching (see reference). Figure 12 (Arrow 73 in the image).

[0070] Through the above processes, the suspension arm 10 is manufactured.

[0071] As described above, the staged bending process in the manufacturing method of the vehicle suspension arm 10 of this embodiment includes a first bending process in which the portion constituting the base 23 of the main body 20 and the portion constituting the first connecting portion 31 of the workpiece W are pressed by the punch 106 (first punch) and pre-bent at the same time, and after the first bending process, the pressing of the punch 106 (first punch) on the portion constituting the first connecting portion 31 is released, and on the other hand, the portion constituting the base 23 of the main body 20 is pressed by the punch 108 (second punch) and bent along the crease formed in the first bending process.

[0072] Furthermore, the vehicle suspension arm 10 of this embodiment is manufactured using the manufacturing method described above.

[0073] With this configuration, at least one pair of first through holes 51 are formed on the workpiece W, each having a cylindrical flange 51a that rises from the plate surface through a flanging process. For the vehicle suspension arm 10 manufactured by performing a staged bending process on the workpiece W, the quality (coaxiality and roundness) of the pair of first through holes 51 can be satisfied. Even if the product width of the first connecting portion 31 (the width between the first flat portions 41) is narrow and it is difficult to use a cam mechanism (mold) to flanging and form the product shape of the first through holes 51, it is possible to mass-produce vehicle suspension arms 10 that meet the quality (coaxiality and roundness) of the pair of first through holes 51.

[0074] In this embodiment, a support mold for the pair of first through holes 51 formed by the flanging process is not required. Therefore, deformation and insufficient strength caused by mold reduction (especially reduction in the thickness direction and the support mold), which are problems related to product width and flanging shape in cam-structured processing, can be avoided. Thus, mold costs can be reduced through the mold's own structure, fewer mold failures, and increased lifespan. Furthermore, preparation time can be reduced, and consistent flanging quality can be obtained. Moreover, since the constraints of product width reduction and the peripheral shape of the first through holes 51 are eliminated, the freedom of layout design increases, contributing to both high strength and lightweight design.

[0075] The pre-bending in the first bending process is performed simultaneously by pressing the two side walls 21 and 22 that constitute the main body 20 with the punch 106 (first punch). With this configuration, the crease 72 can be formed correctly.

[0076] The portion constituting the first connecting part 31 includes the plate surface surrounding the raised flange 51a. The pre-bending in the first bending process is performed simultaneously by pressing the plate surface surrounding the flange 51a with the punch 106 (first punch). This configuration allows for the formation of the crease 72 while more accurately maintaining the coaxiality and roundness of the first through hole 51.

[0077] The phased bending process includes a third bending process following the second bending process. In this third bending process, bending is performed while the punch 106 (first punch) is released from pressing on the portion constituting the first connecting portion 31. This bending continues until the portion constituting the base 23 of the main body 20 is pressed by the punch 110 (third punch), causing the portions constituting the two sidewalls 21, 22 to face each other, and the axes of the pair of first through holes 51 of the first connecting portion 31 to be aligned. With this configuration, the two sidewalls 21, 22 of the main body 20 can be bent at 90 degrees relative to the base 23, and the two first flat portions 41 of the first connecting portion 31 can be parallel to each other.

[0078] The base 23 of the main body 20 has a curved shape whose dimensions gradually increase towards the end in the X direction as it connects with the line segments on the surfaces of the side walls 21, 22 along the X direction. The staged bending process also includes a step in which the portion constituting the base 23 is bent into a curvature consistent with the curved shape in the workpiece W before the pair of first through holes 51 are formed. With this configuration, the arm can be lightweighted by means of the curved shape of the suspension arm 10.

[0079] The ends of the sidewalls 21 and 22 opposite to the base 23 have a curved shape whose dimensions gradually increase with the length of the line segment on the surface of the sidewalls 21 and 22 along the X direction. With this configuration, the arm can be lightweight by means of the curved shape of the suspension arm 10.

[0080] The main body 20 has inward ribs 24 and 25, in a cross section orthogonal to the X direction, where the end faces of two side walls 21 and 22 face each other. The staged bending process also includes a rib bending process in the workpiece W before forming a pair of first through holes 51, where the portions constituting the inward ribs 24 and 25 are bent. With this configuration, a hollow shape can be formed in which the end faces of the two side walls 21 and 22 of the main body 20 face each other with open surfaces separated by a gap 26.

[0081] (Examples of variations in the shapes of the die and punch)

[0082] Figure 13 (A) to (D) are cross-sectional views showing examples of deformation of the die and punch used in the second bending process.

[0083] The cross-sectional shape of the base 23 of the main body 20 is not limited to the planar shape shown in the embodiment (see reference). Figure 9 In case (B), the shape can be changed appropriately.

[0084] Figure 13(A) The concave die 121 and convex die 122 form the cross-sectional shape of the base 23 into an M-shaped curved shape. Figure 13 (B) The concave die 123 and convex die 124 form the cross-sectional shape of the base 23 into a U-shaped curved shape. Figure 13 (C) The concave die 125 and convex die 126 form the cross-sectional shape of the base 23 into a curved shape. Figure 13 (D) The concave mold 127 and convex mold 128 form the cross-sectional shape of the base 23 into a shoulder R (arc) slope shape.

[0085] The present invention is not limited to the embodiments described above, and appropriate modifications can be made. For example, the second through hole 52 can be formed by flanging.

[0086] The suspension arm 10 of the embodiment has Figure 3 The invention is not limited to the form shown in (A). The invention can also be applied to... Figure 3 (B) and Figure 3 (C) shows the configuration of suspension arms 60b, 60c. Furthermore, although the illustration is omitted, the present invention can also be applied to suspension arms with a curved shape at the base 23 of the main body 20 and a straight shape at the ends of the sidewalls 21, 22 opposite to the base 23 (above the inward ribs 24, 25).

Claims

1. A method for manufacturing a vehicle suspension arm, wherein the method comprises forming at least a pair of through holes having cylindrical flanges rising from a plate surface on a workpiece by flanging, and performing staged bending operations on the workpiece to manufacture a vehicle suspension arm having a hollow main body and connecting portions opposite each other with the axes of the pair of through holes aligned, characterized in that, The main body has two opposing sidewalls and a base connecting the two sidewalls to each other, and extends in one direction. The connecting portion extends from the ends of the two sidewalls in that one direction and is spaced apart from each other. The staged bending process has The first punch presses down on the base portion constituting the main body and the connecting portion of the workpiece, while simultaneously performing a first bending pre-bending process. After the first bending process, the pressure of the first punch on the portion constituting the connecting part is released, and the portion constituting the base of the main body is pressed by the second punch. At the same time, a second bending process is performed along the crease formed in the first bending process. The portion constituting the connecting part includes the plate surface surrounding the raised flange. The pre-bending in the first bending process is performed by pressing the plate surface around the flange with the first punch.

2. The method for manufacturing a vehicle suspension arm as described in claim 1, wherein, The pre-bending in the first bending process is performed by pressing the two sidewalls that make up the main body using the first punch.

3. The method for manufacturing a vehicle suspension arm as described in claim 1, wherein, The staged bending process also includes a third bending step. After the second bending process, the third bending process is performed while the first punch is released from pressing on the part constituting the connecting portion, until the part constituting the base portion of the main body portion is pressed by the third punch, and the parts constituting the two sidewalls are opposite to each other, and the axes of the pair of through holes of the connecting portion are aligned with each other.

4. The method for manufacturing a vehicle suspension arm as described in claim 1, wherein, The base of the main body has a curved shape in which the dimension between itself and a line segment on the surface of the sidewall along the one direction gradually increases with the end toward the one direction. The staged bending process also includes a step of bending a portion constituting the base into a curvature consistent with the bending shape in the workpiece before forming a pair of through holes.

5. The method for manufacturing a vehicle suspension arm as described in claim 1, wherein, The end of the sidewall opposite to the base has a curved shape whose dimensions with respect to a line segment on the surface of the sidewall along the one direction gradually increase as the end toward the one direction approaches.

6. The method for manufacturing a vehicle suspension arm as described in claim 1, wherein, The main body has inward ribs in a cross-section orthogonal to the one direction, where the end faces of the two sidewalls face each other. The staged bending process also includes a rib bending process in which the portion constituting the inward rib is bent in the workpiece before the pair of through holes are formed.

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