[0001]This invention produces torsion beam applied to metal fatigue is suppressed in torsion beam suspension apparatus for an automobile, to a torsion beam manufacturing method and torsion beam manufacturing apparatus. Further, the present invention relates to a torsion beam produced by these torsion beam manufacturing method and torsion beam manufacturing apparatus.
　This application, in May 10, 2016, claiming priority on Japanese Patent Application No. 2016-094819 filed in Japanese, which is incorporated herein by reference.
BACKGROUND
[0002]
　As is well known, torsion beam suspension apparatus have been widely used as a form of automotive suspension systems.
　The torsion beam suspension apparatus: is connected a pair of left and right trailing arms for rotatably supporting the left and right wheels by the torsion beam further comprises a torsion beam assembly pair of left and right spring receiving portions are joined to the left and right ends near the torsion beam; torsion beam and a spring and absorber for connecting the vehicle body; comprising a. The torsion beam is, via a pivot axis extending from the left and right of the vehicle body toward the center side, are swingably connected to the vehicle body.
[0003]
　Torsion beam, for example, is formed by plastic working a metal pipe by press molding and hydro forming, in cross section perpendicular to the longitudinal direction of the torsion beam, toward the mounting portion of the trailing arm to a constant shape closed-section portion It is formed on the closed section of the substantially V-shaped or substantially U-shaped Te (e.g., see Patent Document 1).
[0004]
　The torsion beam is provided with a predetermined shape closed cross-section portion, and a mounting portion connected to the left and right trailing arms, longitudinal shape changing portion located between predetermined shape closed-section portion and the mounting portion (gradually changing portion) , when the vehicle body is subjected to an external force from the road surface so as to ensure the roll stiffness of the vehicle body by torsional rigidity mainly torsion beam.
[0005]
　On the other hand, even torsion beam had sufficient roll stiffness, torsion beam, for receiving a variety of external force from the road surface through the wheels and trailing arm, complex stress distribution due to such external force is generated to.
　Therefore, even when subjected to various external forces from the road surface, it is necessary to suppress the development of metal fatigue, various techniques have been developed to suppress such metal fatigue (e.g., Patent Documents 2 and 3 , see 4.).
[0006]
　The technique described in Patent Document 2, after press forming torsion beam, quenching, tempering, performing shot peening, by curing the outer surface of the torsion beam, improve the fatigue properties of the torsion beam.
[0007]
　The technique described in Patent Document 3, by using a steel pipe surface hardness is high after the heat treatment, to improve the surface hardness of the torsion beam, improve the fatigue properties of the torsion beam.
[0008]
　The technique described in Patent Document 4, by applying a tensile stress to the torsion beam, improve the fatigue properties by reducing the residual stress of the torsion beam.
CITATION
Patent Document
[0009]
Patent Document 1: Japanese Patent 2011-635 JP
Patent Document 2: Japanese Patent 2001-123227 JP
Patent Document 3: Japanese Patent 2008-063656 JP
Patent Document 4: Japanese Patent 2013-091433 No.
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　However, to improve the fatigue properties of the torsion beam by applying the technique described in Patent Documents 2 to 4, on which not necessarily easy, there is a problem of initial costs and production running costs such as equipment investment increases . Therefore, the torsion beam fatigue characteristics excellent, easily and efficiently torsion beam manufacturing techniques that can be produced is desired.
[0011]
　The present invention has been made in view of such circumstances, and an object thereof is to provide a superior torsion beam fatigue properties. Further, the present invention is capable of producing such torsion beam easily and efficiently, also aims provide a torsion beam manufacturing method and torsion beam manufacturing apparatus.
Means for Solving the Problems
[0012]
　The inventors of the present invention made intensive studies on techniques for improving the fatigue properties of the torsion beam used in the torsion beam suspension of a motor vehicle. As a result, the closed section of the substantially V-shaped or substantially U-shaped, the folded wall portion that connects the second wall section forming the first wall portion and the convex side outer surface forms a concave side outer surface (ears) stress easily concentrated, by processing the thickness of the folded wall portion thicker than the first wall portion and the second wall portion, it is possible to alleviate the stress concentrated on the folded wall portion efficiently, the torsion beam the fatigue properties of knowledge was obtained that it is possible to efficiently increase.
　Then, obtained in processing the folded wall portion thicker, by causing a compressive stress along the closed cross-section, a large effect on decreasing the residual stress of the folded wall portion suppresses development of metal fatigue it was found that to be.
[0013]
　In order to solve the above problems, the present invention proposes the following means.
(1) torsion beam manufacturing method according to an embodiment of the present invention, a cross section perpendicular to the longitudinal direction, and the constant shape closed cross-section portion is a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ears, the constant shape and shape change unit which changes in accordance with closed continuous to the surface and the shape of the closed section away from said predetermined shape closed cross-section portion, a method of manufacturing a torsion beam with a, at least the shape change unit, while supporting the both outer side surfaces of each of the pair of ear portions, increasing to form a pair of thickened portion is pressed from the outside of the pair of ear portions respectively to resist bulging of the pair of ear portions with a meat process.
　Before the thickening step, the residual stress is generated in each unit including a pair of ears. According to the embodiment described in the above (1), the residual stress in the thickness increasing process, by plastically deforming by pressing from outside a pair of ears, it can be eliminated or reduced. Eliminate or reduce such residual stress is conventionally not obtained form unless special processing such as hydroformed, it takes a great effort. This aspect can be dropped residual stress in a simple press working without requiring such effort.
[0014]
The torsion beam manufacturing method described in (2) above (1), in the thickening process, except for the pair of ear portions, while supporting the inner surface of the closed section, to press the pair of ear portions it may be.
　In the case of (2), since it is possible to prevent deformation in favor of portions other than a pair of ears, the pressing force applied to the pair of ears, to concentrate the thickening processing of the pair of ear portions be able to. As a result, it is possible to more reliably eliminate or reduce the residual stress of each part including a pair of ears.
[0015]
(3) In the torsion beam manufacturing method according to (1) or (2), in the thickening step, the maximum value of the thickness in the thickening section, the plate in the portion other than the thickening portions of the same cross-section thick so that 1.01 to 1.50 times, or by pressing the pair of ear portions.
[0016]
(4) torsion beam manufacturing apparatus according to an embodiment of the present invention, a cross section perpendicular to the longitudinal direction, and the constant shape closed cross-section portion is a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ears, an apparatus for manufacturing a torsion beam and a shape changing portion which changes according to the shape of said predetermined shape closed continuous to face and the closed section away from said predetermined shape closed-section portion, the pair of ear portions both comprises; a first mold for supporting the both outer surfaces; a second mold to press inwardly of the closed section than the outer top portion of the pair of ear portions both.
　Prior to thickening processing by torsion beam manufacturing apparatus of the embodiments described in the above (4), the residual stress is generated in each unit including a pair of ears. In this manner, while supporting the both outer surfaces of the pair of ear portions both by the first mold, the top of the pair of ear portions both by the second die towards than outside inwardly closed section by plastic deformation pressed, it is possible to eliminate or reduce the residual stress. Eliminate or reduce such residual stress is conventionally not obtained form unless special processing such as hydroformed, it takes a great effort. This aspect can be dropped residual stress in a simple press working without requiring such effort.
[0017]
(5) In the above torsion beam manufacturing apparatus according to (4), said out of closed plane, it may further comprise a third mold for supporting the inner surface excluding the pair of ear portions.
　Above (5), the it is possible to prevent deformation in favor than inner portions other than a pair of ears in the third die, the pressing force applied to the pair of ears, a pair it can be concentrated to increase meat processing ears. As a result, it is possible to more reliably eliminate or reduce the residual stress of each part including a pair of ears.
[0018]
(6) torsion beam according to one aspect of the present invention, a cross section perpendicular to the longitudinal direction, a constant shape closed cross-section portion and a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ears, the constant and radius variations which varies in accordance with continuous to form closed-section portion and the shape of the closed section away from said predetermined shape closed-section portion; wherein the pair of ear portions, respectively, in at least the shape change portion, of the pair None the thickened portion thickness is increased than the portion other than the ear portion; residual stress in the thickest location of the thickness of each of thickened portions, is estimated from the Vickers hardness at the outer surface of the thickest position it is 70% or less of that tensile strength.
　The pair of ears before thickened portion is formed, the residual stress has occurred in each unit containing a pair of ears. However, the torsion beam embodiment described above (6) has been produced by the torsion beam manufacturing apparatus aspects described torsion beam manufacturing method or the aspects described (4) to (1), the above-mentioned reasons residual stress is eliminated or reduced by. Then, as a result, residual stress in the thickest location of the plate thickness of each of thickened portions becomes less tensile 70% of the intensity estimated from Vickers hardness at the outer surface of the thickest position.
[0019]
Torsion beam according to (7) above (6), wherein the thickness at the thickest location, may be 1.01 to 1.50 times the thickness of the portion other than the thickening portions of the same cross-sectional .
Effect of the invention
[0020]
　According to the above aspect of the present invention can provide an excellent torsion beam fatigue properties. Further, capable of producing such torsion beam easily and efficiently, it can also provide the torsion beam manufacturing method and torsion beam manufacturing apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
FIG. 1 is a perspective view illustrating a schematic configuration of a torsion beam type rear suspension apparatus according to an embodiment of the present invention.
[Figure 2] A diagram illustrating a schematic configuration of a torsion beam assembly according to the embodiment is a perspective view from below.
3 is a perspective view illustrating a schematic configuration of a torsion beam according to the embodiment.
4 is a perspective view illustrating a schematic configuration of a longitudinal shape change of the torsion beam.
[Figure 5A] is a sectional view showing a schematic structure of the torsion beam, a closed cross-section indicated by palm VA-VA in FIG.
[Figure 5B] is a sectional view showing a schematic structure of the torsion beam, a closed cross-section indicated by palm VB-VB in FIG.
6 is a flowchart illustrating an example of a torsion beam of the manufacturing process according to the embodiment.
[FIG 7A] is a front view for explaining an example of a torsion beam manufacturing apparatus according to the embodiment.
[Figure 7B] is a view for explaining an example of a torsion beam manufacturing apparatus according to the embodiment, a sectional view showing by arrow VIIB-VIIB in FIG. 7A.
[Figure 7C] is a view for explaining an example of a torsion beam manufacturing apparatus according to the embodiment, a sectional view showing by arrow VIIC-VIIC in FIG. 7A.
A diagram for explaining the position of Figure 7B an example of a manufacturing process of the torsion beam according to FIG. 8A] the embodiment, a cross-sectional view showing a state of arranging the torsion beam material on the lower fixed mold.
A diagram for explaining the position of Figure 7B an example of a manufacturing process of the torsion beam according to FIG. 8B] the embodiment, a cross-sectional view showing a state of inserting the punch type torsion beam material was set on the lower fixed mold.
A diagram for explaining the position of Figure 7B an example of a manufacturing process of the torsion beam according to FIG. 8C] the embodiment, a cross-sectional view showing a state of pressing on the movable-type torsion beam material was set on the lower fixed mold.
A diagram for explaining the position of Figure 7B an example of a manufacturing process of the torsion beam according to FIG. 8D] to the embodiment, the upper movable die, the lower fixed mold, folded wall portion of the torsion beam materials were restrained by a punch-type (ears) is a sectional view showing a state of pressing the.
A diagram for explaining the position of Figure 7C an example of a manufacturing process of the torsion beam according to FIG. 9A] the embodiment, a cross-sectional view showing a state of arranging the torsion beam material on the lower fixed mold.
A diagram for explaining the position of Figure 7C an example of a manufacturing process of the torsion beam according to FIG. 9B] the embodiment, a cross-sectional view showing a state of pressing on the movable-type torsion beam material was set on the lower fixed mold.
A diagram for explaining the position of Figure 7C an example of a manufacturing process of the torsion beam according to FIG. 9C] the embodiment, presses folded wall portion of the torsion beam material was restrained on a movable die and a lower fixed mold (the ears) it is a cross-sectional view illustrating a state.
In the manufacturing process of the torsion beam according to FIG. 10A] the embodiment, showing a stress generated in thickened scheduled processing unit at the time of forming the torsion beam material.
In the manufacturing process of the torsion beam according to FIG. 10B] same embodiment, showing the stress generated during the thickening process the thickness increase scheduled processing unit.
In the manufacturing process of the torsion beam according to FIG. 10C] same embodiment, showing the residual stress in the thickened section.
[Figure 11] A perspective view showing an embodiment using the analysis to verify the effects of the present invention, (A) is a preparation step, (B) is press working step, after processing (C) It shows the torsion beam.
[Figure 12] A sectional view showing a residual stress distribution in the torsion beam after processing in the embodiment, shows a comparative example that does not perform thickening step (A), (B) and (C) is thickened illustrate the present invention example in which the step.
DESCRIPTION OF THE INVENTION
[0022]
　Hereinafter, with reference to the accompanying drawings, a description will be given of an embodiment of the present invention.
　Figure 1 is a perspective view showing a schematic configuration of a torsion beam type rear suspension apparatus according to the present embodiment (torsion beam suspension apparatus). In the figure, reference numeral 1 denotes a torsion beam type rear suspension apparatus, reference numeral 2 denotes a torsion beam assembly, reference numeral 10 denotes a torsion beam. Reference numeral F shown in FIG. 1 shows the front of the vehicle (not shown) that the torsion beam type rear suspension apparatus 1 is mounted, reference numeral R represents the rear.
[0023]
　Torsion beam type rear suspension apparatus 1, as shown in FIG. 1, for example, includes a torsion beam assembly 2, a spring 3 and absorber and 4 for connecting the torsion beam assembly 2 and the vehicle body (not shown), a.
　The torsion beam assembly 2, the left and right wheels WL, while supported by a pair of left and right trailing arms 5 a WR, pivot shaft JL extending toward slightly front center side of the vehicle body from the left and right of the vehicle body, said vehicle body via the JR it has been linked. The torsion beam assembly 2 is pivotable relative to the vehicle body.
[0024]
　The torsion beam assembly 2, as shown in FIG. 2, for example, a pair of left and right trailing arms (arm) 5, and torsion beam 10 for connecting the these trailing arm 5, a pair of left and right spring receiver for supporting the spring 3 and a 3A. Further, one end side of the absorber 4 is a buffer device is connected to a buffer receiving portion (not shown).
　In the present embodiment, the torsion beam 10, FIG. 1, as shown in FIG. 2, has a closed cross section of the substantially V-shape is convex upward.
[0025]
　Trailing arm 5, as shown in FIG. 2, for example, a pivot mounting member supported and the trailing arm body 5A, connected to the front end of the trailing arm body 5A in the vehicle body via a pivot shaft J and 5F, is coupled to the rear end wheel WL of the trailing arm body 5A, and a wheel mounting member 5R supporting the WR.
[0026]
　Spring receiver 3A is arranged on the opposite side of the pivot mounting members 5F sandwiched between the torsion beam 10, one end of the spring 3 is mounted. Load received from the road surface is, the wheels WL, WR, trailing arm 5, and is transmitted to the vehicle body via a spring 3.
[0027]
　Referring to FIGS 5B, described torsion beam 10 according to this embodiment.
　Figure 3 is a perspective view illustrating a schematic configuration of the torsion beam 10 according to this embodiment. Figure 4 is a perspective view illustrating a longitudinal shape changes the vicinity of the torsion beam 10. Figure 5A, Figure 5B is a cross-sectional view of the torsion beam 10, FIG. 5A shows a cross section at arrow VA-VA in FIG. 4, FIG. 5B shows a cross section at arrow VB-VB in FIG. 4 .
[0028]
　Torsion beam 10, as shown in FIGS. 3 and 4, a constant shape closed-section portion 11 having a closed cross section of constant shape of a substantially V-shape is formed on the center side in the longitudinal direction, the longitudinal shape changing portion 12 a mounting closed cross-section portion 13, and has a closed cross section of substantially elliptical shape are formed at the outer end of the attachment closed cross-section portion 13, and a mounting portion 14 trailing arm 5 is attached.
[0029]
　Constant shape closed cross-section portion 11, longitudinal shape changing portion 12, the attachment closed cross-section portion 13, the mounting portion 14 is formed in this order toward both ends from the longitudinal center of the torsion beam 10.
[0030]
　Constant shape closed-section portion 11, as shown in FIGS. 3 and 4, are located in the center of the longitudinal direction of the torsion beam 10, and is connected to each longitudinal shape changing portion 12 at its longitudinal ends.
　Constant shape closed-section portion 11, when viewed in cross section perpendicular to the torsion beam 10 in the longitudinal direction, forming a substantially uniform closed cross section of the substantially V-shaped or substantially U-shaped in succession along the longitudinal direction is a portion that is. Torsion beam 10 of the present embodiment has a shape which is symmetrical in the longitudinal direction of the vehicle body. Note that in certain shape closed portion 11, the valley portions of the wall portion constituting the concave side of the substantially V-shaped or substantially U-shaped (bottom), it may be partially irregularities formed.
[0031]
　As shown in FIG. 4, the longitudinal shape changing portion 12, the longitudinal inboard torsion beam 10 is connected to a constant shape closed cross-section portion 11, towards the longitudinal outer is connected to the mounting closed cross-section portion 13.
　Further, the longitudinal shape changing portion 12, closed cross section perpendicular to the longitudinal direction of the torsion beam 10 is gradually changed toward the predetermined shape closed cross-section portion 11 to the mounting closed cross-section portion 13. That is, the shape changing portion 12, the valley portions of the wall portion constituting the concave side of the substantially V-shaped or substantially U-shaped depth (bottom) toward the longitudinal outside (vehicle width direction outside) it is gradually shallow become part. Incidentally, in the middle of the shape changing portion 12, portions of valleys (bottom) is further shallower may be partially formed.
[0032]
　Longitudinal shape changing portion 12, as shown in FIG. 5A is a cross-section shown in arrow VA-VA in FIG. 4, the first wall portion 110 which forms the concave side outer surface in the closed section of the substantially V-shaped, the closed a second wall portion 120 forming the convex side outer surface in the cross section, the two folded wall portion 130 that bulges outward in the closed section forms the two ends of the first wall portion 110 and the second wall portion 120, respectively (a pair is equipped with ears), the. Each folded-back wall portions 130, thickened section 140 is formed.
[0033]
　The thickening process refers to a process of forming thicker than both the thickened scheduled processing unit first wall portion 110 and the second wall portion 120.
[0034]
　Further, the folded wall portion 130 includes the end portions of the first wall portion 110 and the second wall portion 120, with bulging outward from the inside in the closed section of the substantially V-shaped or substantially U-shaped, a first wall portion side turn point 131 is a wall portion which is located between the second wall portion side turn point 132.
[0035]
　Thickened processing section 140, in this embodiment, of the torsion beam 10, the total length excluding mounting closed cross-section portion 13, that is, formed into a predetermined shape closed cross-section portion 11 and the longitudinal radius variations 12. However, not limited to this embodiment, it may be formed thickened section 140 only in the shape changing part 12. The shape changing portion 12 for particular strength a portion that varies in shape along the longitudinal direction is required, it is effective to form a thickened section 140 to at least the shape changing portion 12.
[0036]
　Incidentally, by forming the thickened section 140, as compared with the plate thickness is uniform over both the circumferential direction and the entire length of the torsion beam 10, the roll stiffness is increased. On the other hand, in the vehicle body design, since roll stiffness required for the torsion beam 10 are determined within a predetermined range, roll stiffness of the torsion beam 10 is an actual product is undesirable higher or lower than the design value. Therefore, the bringing the roll stiffness to a predetermined design value, and reduction of residual stress, it is required to achieve at the same time. For example, if the roll stiffness deviates from the design value by the formation of thickened portions, by previously thin thickness of the torsion beam 10 (circumferential length) at the design stage, to balance the two conditions of the it can be.
[0037]
　In the longitudinal direction the shape changing portion 12, a first wall portion 110 and the second wall portion 120 are spaced apart from each other, substantially V-shaped between the first wall portion 110 and the second wall portion 120 hollow portion 150A is formed of.
　Further, the longitudinal shape changing portion 12 has a symmetrical shape in the longitudinal direction of the vehicle body.
[0038]
　Folded wall portion 130, as shown in FIG. 5A, is formed between the first wall portion side turn point 131 and the second wall portion side turn point 132.
[0039]
　Thickened processing unit 140, for example, is formed over the entire length in a direction along the closed section of the two folded wall portion 130. That is, thickened processing unit 140, along the first wall portion 110 and the plate thickness equal first wall portion side turn point 131 in closed section gradually thickness is increased the maximum thickness at the top, turn the top gradually decreases the thickness along the more closed cross section, and finally has a shape leading to the second wall portion 120 and the plate thickness equal second wall portion side turn point 132.
[0040]
　Maximum thickness of the thickened section 140 (mm), the relative thickness of the first wall portion 110 and the second wall portion 120 (e.g., 1.0 mm-5.0 mm), for example, 101% - 150% (1.01 to 1.50 times. preferably 1.05 times to 1.50 times greater than) have been a, toward the maximum thickness portion from each end of the first wall portion 110 and the second wall portion 120 It is increasingly thickened Te.
　Note relates measurements of each part thickness, with the maximum thickness for thickened section 140, it is preferable to use the average value thereof was measured several points wall thickness except for the thickened section 140.
[0041]
　Constant shape closed-section portion 11, as shown in FIG. 5B is a cross-section shown in arrow VB-VB in FIG. 4, the first wall portion 110 which forms the concave side outer surface in the closed section of the substantially V-shaped, the closed includes a second wall portion 120 forming the convex side outer surface in cross-section, the two folded wall portions 130 which are connected to both ends of the first wall portion 110 and the second wall portion 120, respectively bulged outwardly, the ing. Each folded-back wall portions 130, thickened section 140 is formed.
　A first wall portion 110 and the second wall portion 120 are in contact with each other via the contact portion 150B.
[0042]
　Folded wall portion 130, as shown in FIG. 5B, which is formed between the first wall portion side turn point 131 of the second wall portion side turn point 132.
[0043]
　Thickened section 140 is formed over the entire length in a direction along the closed section of the two folded wall portion 130.
[0044]
　Maximum thickness of the thickened section 140 (mm), the relative thickness of the first wall portion 110 and the second wall portion 120 (e.g., 1.0 mm-5.0 mm), for example, 101% - 150% (1.01 to 1.50 times. preferably 1.05 times to 1.50 times greater than) have been a, toward the maximum thickness portion from each end of the first wall portion 110 and the second wall portion 120 It is increasingly thickened Te.
[0045]
　Mounting closed-section portion 13 in the longitudinal direction of the torsion beam 10 have been formed on the outer side of the longitudinal shape changing portion 12, the outer end portion is a mounting portion 14. Mounting closed-section portion 13 has a closed cross section of the same substantially elliptical shape as the mounting portion 14. Mounting closed-section portion 13 is disposed longitudinally outward of the shape-changing portion 12 (the vehicle width direction outside), refers to a moiety that is concave having a substantially V-shaped or substantially U-shaped not formed.
[0046]
　Next, with reference to FIG. 6, the outline of the manufacturing process of the torsion beam 10 according to this embodiment. Figure 6 is a flowchart showing manufacturing steps of the torsion beam 10. 6, a block of single frame indicates an article, blocks of the double frame shows the process.
[0047]
　Referring to FIG 6, a description will be given of a manufacturing process of the torsion beam 10.
(1) preparing a metal material tube (step S101).
　The metal material pipe to be prepared, for example, it is possible to wall thickness using a uniform circular steel tube.
(2) Next, pressing a metal material tube (step S102).
　In the press working of a metal material tube, of the outer shape of the torsion beam 10, the portion other than the thickened section 140 is shaped into a final shape, as thickened scheduled processing section to the portion corresponding to the thickened section 140, the torsion beam 10 It is molded to the displacement shape outward from the outer.
(3) pressing a metal material tube in the above (2) (step S102), the torsion beam material is formed (step S103).
(4) Then, the boosted meat processing and thickened section 140 to press the thickened scheduled processing section of the torsion beam material (step S104).
The thickening process in (5) above (4), the torsion beam 10 is formed (step S105).
[0048]
　The torsion beam manufacturing method according to the present embodiment, at step S104, with at least a longitudinal shape changing portion 12, folded wall portions 130 (a pair of ear portions) supporting each of both outer surfaces, swelling of the folded wall portion 130 as against, it is performed thickening forming a pair of thickened portion by pressing the respective top folded wall portion 130 toward from outside inward.
　The thickening process before each folded-back wall portion 130, the residual stress at the time of forming these folded wall portion 130 occurs. The residual stress, in the thickening step, and a folded wall portion 130 is pressed from the outside by plastic deformation is eliminated or reduced. Such folded wall portion 130 which is thickened in the, compared to other portions, but the hardness is increased residual stress by work hardening is increased is reduced, and also the plate thickness.
[0049]
　With particular describe the residual stress, torsion beam 10 of the present embodiment, the residual stress at the thickest position (top) of the respective plate thickness folded wall portion 130, tension is estimated from a Vickers hardness in the outer surface of the thickest position and has a 70% strength or less.
[0050]
　Considering the fatigue strength of the torsion beam 10 improves, since it is particularly eliminate or reduce the residual stress at the folded wall portion 130 forming the ear part is effective, pressurizes the pair of folded wall portions 130 in the present embodiment It is made to meat increase Te. Pressure at this time, mainly but used thickening of the pair of folded wall portions 130, it is being transmitted to result in a portion other than these folded wall portion 130. More specifically, for example, in Figure 5B, the forming a portion 120a extending from the bottom portion 120b of the second wall portion 120 forming a V-shape to the second wall portion folding point 132 on both sides, the same V-shape also both from the bottom 110b of the first wall portion 110 and the portion 110a reaching the first wall portion folding point 131 on both sides thereof, so that the compressive force along the closed cross-section is applied. This compressive force, the portion 110a, thereby eliminating or reducing the residual stress in both 120a. Thus, thickening processing of the present embodiment is carried out to eliminate or reduce the residual stress in the pair of folded wall portions 130 as the main purpose, simultaneously secondarily, the residual stress of the other parts are also eliminated or It has become a possible reduction.
[0051]
　Incidentally, when estimating the tensile strength from Vickers hardness is, for example, SAE (Society of Automotive Engineers: Society of Automotive Engineers) for defined in SAE J 417 is a standard, conversion table between tensile strength and Vickers hardness and it can be used an approximate expression (the following equation (1)). In equation (1), TS denotes the tensile strength of the unit MPa, Hv denotes Vickers hardness.
[0052]
　TS = 3.12 × Hv + 16 · · · (1) of formula
[0053]
　Further, the residual stress at the thickest position (top) of the plate thickness of each of the folded wall portions 130 is determined by performing X-ray measurement with respect to the outer surface of the thickest position. As the apparatus used in the X-ray measurement, can be used, for example the following device suitably.
- device name: manufactured) manufactured by Rigaku PSPC / MS F-2M
-characteristic X-ray: CrKarufa
-scanning method: 2θ-sin2Ψ method (side傾法)
[0054]
　Incidentally, the thickness increasing process in the step S104, or thickened treatment after thickened scheduled processing unit is formed to a predetermined time elapses at step S102, or meat up continues immediately after the thickened scheduled processing unit is formed for either process, it can be set arbitrarily.
[0055]
　Next, with reference to FIGS. 7A ~ Figure 7C, illustrating a schematic configuration of a torsion beam manufacturing apparatus according to this embodiment. In FIG. 7A ~ Figure 7C, reference numeral 100 denotes a torsion beam manufacturing apparatus.
[0056]
　7A is a front view for explaining an example of a torsion beam manufacturing apparatus according to this embodiment. 7B is a cross-sectional view of the torsion beam manufacturing apparatus 100 shown in palm VIIB-VIIB in FIG. 7A. 7C is a cross-sectional view of the torsion beam manufacturing apparatus 100 shown in arrow VIIC-VIIC in FIG. 7A.
[0057]
　The torsion beam manufacturing apparatus 100, for example, FIGS. 7A, 7B, as shown in FIG. 7C, the lower fixed mold (a second wall portion supporting) D110, the upper movable die (first wall-supporting) D120, punch -type P100, the thickness increasing process pressure member D130, and a top movable mold pressing springs S100.
[0058]
　Lower fixed D110 also serves as a press-molding the lower mold for molding the second wall portion 120 of the torsion beam material M10 and torsion beam 10. Upper movable mold D120 also serves as a press-molding upper die for molding the first wall portion 110 of the torsion beam material M10.
[0059]
　Further, a lower fixed mold D110, an upper movable mold D120, punch-type P100 constitutes a torsion beam material supporting member.
　The torsion beam material support member, the support portion of the torsion beam material M10 (e.g., supportable sites other than thickened scheduled processing unit) supports the, being deformed upon addition thickened scheduled processing unit is increased Meat to suppress.
[0060]
　The torsion beam material M10, for example, FIG. 7B, as shown in FIG. 7C, the first wall portion 110 which forms the concave side outer surface in a substantially V-shaped closed cross-section, a second wall portion 120 forming the convex side outer surface, folded a folded-back wall portion scheduled portion M130 corresponding to the wall portion 130, and a thickened scheduled processing unit M140 corresponding to the thickened section 140 is formed between the folded-back wall portion scheduled portion M130, a.
[0061]
　The first wall portion 110 of the torsion beam material M10, for the second wall portion 120 is the same shape as the torsion beam 10.
　On the other hand, the folded wall portion scheduled portion M130 of the torsion beam material M10, and the thickness increase scheduled processing unit M140 includes the torsion beam 10 and the shape is different.
[0062]
　Lower fixed to the (second wall-supporting) D110, the second wall portion support recess D110U is being formed, by arranging a second wall portion 120 of the torsion beam material M10 to the second wall portion support recess D110U , to support the second wall portion 120 side of the torsion beam material M10 from below.
[0063]
　Upper movable mold A (first wall-supporting) D120, have been the first wall portion supporting the pressing portion D120P is formed above the first wall portion 110 of the torsion beam material M10 by the first wall portion supporting the pressing portion D120P It is pressed from, to support.
[0064]
　Punch type P100, from the openings of both ends of the torsion beam material M10 (mounting portion 14), mounting the closed-section portion 13 of the torsion beam material M10, is insertable in the longitudinal direction the shape changing portion 12, inwardly of respective sections of the torsion beam material M10 to support from.
[0065]
　Thickening process pressing member D130 has a guide portion D130A, and a thickened section formed recess D130U.
　Thickening process pressing member D130 is toward the lower fixed mold D110, the upper movable die D120, the thickness increase scheduled processing unit M140 of the punch-type P100 torsion beam material M10 that is supported by (torsion beam material supporting member) from the outside inwards to press.
[0066]
　Upper movable die push-up springs S100 is mounted between the thickened process pressing member D130 and the upper movable die (first wall-supporting) D120. Upper movable die push-up springs S100, when presses the thickening process the pressing member D130 by the press drive portion (not shown), the first wall portion of the torsion beam material M10 while being gradually compressed by the first wall portion supporting the pressing portion D120P 110 pressing the and support.
　Then, the by pressing the thickened process pressing member D130 by the press drive portion further large pressing force, to press the thickened scheduled processing unit M140, which thickened handle thickened scheduled processing unit M140.
　When the press drive portion raises the thickening process the pressing member D130, the upper movable die push-up springs S100 decompresses, the upper movable mold a thickening process pressing member D130 (first wall-supporting) from D120 It is moved away.
[0067]
　Next, with reference to FIGS. 8A ~ Figure 8D, in molding the torsion beam material M10 to the torsion beam 10 by the torsion beam manufacturing apparatus 100 will be described processing in the position of Figure 7B.
[0068]
(1) First, as shown in FIG. 8A, by arranging the torsion beam material M10 to the second wall portion supporting the recess D110U lower fixed D110, to support the second wall portion 120 from below.
(2) Next, as shown in FIG 8B, by inserting a punch-type P100 to the hollow portion M150A from both ends of the torsion beam material M10 has been set on the lower fixed mold D110, the first wall portion 110 and the torsion beam material M10 supported from the inside of the second wall portion 120.
(3) Next, as shown in FIG. 8C, lowers the upper movable die D120 in the direction of the arrow T1 by the press drive portion. Then, the first wall portion supporting the pressing portion D120P, supported by pressing the first wall portion 110 of the torsion beam material M10 from above.
　As a result, sites other than the increase in meat processing scheduled portion M140 of the torsion beam material M10 is supported (restraint).
(4) Next, as shown in FIG. 8D, the lower fixed mold D110, the upper movable die D120, a torsion beam material M10 that is constrained by the punch type P100, is pressed by increasing Meat pressing member D130.
　As a result, thickened scheduled processing unit M140 by thickened section forming recess D130U is pressed is thickened processed plastically deformed, thickened section 140 is formed.
[0069]
　Next, with reference to FIGS. 9A ~ Figure 9C, in molding the torsion beam material M10 to the torsion beam 10 by the torsion beam manufacturing apparatus 100 will be described processing in the position of FIG. 7C.
　Note that the following steps, basically, is carried out simultaneously with the step described with reference to FIGS. 8A ~ Figure 8D, may be carried out separately rather than simultaneously.
[0070]
(1) First, as shown in FIG. 9A, by placing a torsion beam material M10 to the second wall portion supporting the recess D110U lower fixed D110, to support the second wall portion 120 from below.
(2) Next, as shown in FIG. 9B, lowers the upper movable die D120 in the direction of the arrow T1 by the press drive portion (not shown). Then, the first wall portion supporting the pressing portion D120P, supported by pressing the first wall portion 110 of the torsion beam material M10 from above.
　As a result, sites other than the increase in meat processing scheduled portion M140 of the torsion beam material M10 is supported (restraint).
(3) Next, as shown in FIG. 9C, the lower fixed mold D110, is pressed by increasing the torsion beam material M10 that is constrained by the upper movable die D120 Meat pressing member D130.
　As a result, thickened scheduled processing unit M140 by thickened section forming recess D130U is pressed is thickened processed plastically deformed, thickened section 140 is formed.
[0071]
　Next, with reference to FIGS. 10A ~ FIG 10C, a description will be given of the operation at the time of thickening process the thickness increase scheduled processing unit M140.
[0072]
(1) First, as shown in FIG. 10A, the metal material pipe is plastically deformed during the molding of the torsion beam material M10, by applying the bending moment MS, tensile outward side of the thickened scheduled processing unit M140 while stress is loaded, the inner side of the thickened scheduled processing unit M140 compressive stress is loaded. As a result, the thickness outward (outer surface and inner surface), the plastic deformation occurs, the thickness inward (central portion), the elastic deformation occurs.
　Then, when the bending moment MS is eliminated by the stop of the press, thickened scheduled processing unit M140 is restored deformed based on the elastic deformation, the elastic deformation and plastic deformation and the stress distribution by pre Fukumoto, double by elastic deformation difference obtained by subtracting the stress change at the time of the original deformation, eventually remain as residual stress.
[0073]
(2) Next, as shown in FIG. 10B, when the thickening process of plastically deforming the thickened scheduled processing unit M140 by pressing the thickened scheduled processing unit M140 in the arrow direction T2, thickened scheduled processing unit M140 overall compressive stress compressive force PS acts occurs in. Therefore, the bending outer side and a compressive stress state inwardly both also becomes a change in stress values thickness direction since the plastic region across small. As a result the thickness direction of the bending moment MS becomes very small, multi-source volume due to elastic deformation when removing the compressive force PS becomes very small, the final residual stress is also very small.
　Thus, residual stress in the bending portion 130 is reduced, the fatigue strength is improved.
[0074]
　According to the torsion beam manufacturing method using the torsion beam manufacturing apparatus 100 according to this embodiment, to support the support portion set in advance of the torsion beam material M10, by thickening process the thickness increase scheduled processing unit, folded wall portions 130 it is possible to manufacture an excellent torsion beam 10 on fatigue properties of efficiently. Here, the "efficient production" is without using a complicated molding process using a conventional such hydraulic shows the meaning of washable residual stress with only mechanical cold forming. In addition, the "preset support site" of the torsion beam material M10, to support at the time of increasing meat processing the increase meat processing scheduled portion of the torsion beam material M10 (restraining), which is the site of the non-thickened scheduled processing unit.
[0075]
　Further, by pressing from the outside to the inside of the closed section of the thickened scheduled processing unit M140 by increasing Meat pressing member D130, since the thickened process while compressing the thickened scheduled processing unit M140 along the closed section fatigue it is possible to produce a characteristic and excellent torsion beam efficiently.
[0076]
　According to the torsion beam manufacturing method using the torsion beam manufacturing apparatus 100 according to the present embodiment, the lower fixed mold D110 which supports the second wall portion 120 of the torsion beam material M10, the first wall portion 110 side of the torsion beam material M10 support an upper movable mold D120 to support the torsion beam material M10 by a punch-type P100 which supports the first wall portion 110 and the second wall portion 120 of the torsion beam material M10 from the inside by (constraining), thickening processing pressing member D130 because pressing the thickened scheduled processing unit M140 by, with a simple configuration and process, it can be formed easily and efficiently thickening processing unit 140 in the folded-back wall portion 130.
[0077]
　According to the torsion beam manufacturing method using the torsion beam manufacturing apparatus 100 according to this embodiment, since the hollow portion 150A is supported from the inside by the punch type P100, without deforming the hollow portion 150A, the thickness increase processing section 140 reliably it is possible to increase meat processing.
　As a result, longitudinal shape changing portion 12 of the torsion beam 10, mounted closed cross-section portion 13, the mounting portion 14 can be processed thickened stably and efficiently.
[0078]
　According to the torsion beam manufacturing method according to the present embodiment, the metallic material tube by plastic working, so forming a torsion beam material M10, it is possible to form the torsion beam material M10 efficiently.
　As a result, it is possible to produce a torsion beam 10 that is fatigue characteristics excellent efficiently.
[0079]
　The present invention is not limited to the above embodiments without departing from the scope and spirit of the present invention, it is possible to make various changes.
　For example, in the above embodiment, the case has been described where the torsion beam 10 is formed into a substantially V-shape which is convex upward when mounted on the vehicle body is applied to a torsion beam which is formed into a substantially U-shaped it may be, may be configured to be convex to the lower side with respect to the vehicle body.
[0080]
　Further, in the above embodiment, the case has been described where the thickened section 140 on both the folded wall portion 130 of the front side and the rear side of the vehicle body in the torsion beam 10 is formed, any vehicle on the front side and the rear side it may be applied to the torsion beam 10 which thickened section 140 is formed either on one of the folded-back wall portion 130.
[0081]
　In the embodiment described above, a certain shape closed cross-section portion 11, but if explained in the longitudinal direction the shape changing portion 12 thickened processor 140 over the entire length of is formed, on any range in the longitudinal direction of the torsion beam 10 it may form a thickened section 140.
[0082]
　Further, in the above embodiment, the case has been described where the thickened section 140 over the entire range in the direction along the closed section of the folded wall portion 130 is formed, thickened processing unit 140 in the direction along the closed cross-section to the extent that forms a can be set arbitrarily, may be formed thickened processing unit 140 in a part of the folded-back wall portion 130.
　Further, in the direction along the closed section, it may be formed thickened section 140 in a range exceeding the folded wall portion 130.
[0083]
　Further, in the above embodiment, the case has been described where the inner side of the closed cross section of constant shape closed-section portion 11 and the first wall portion 110 which constitutes the second wall portion 120 is formed in close contact, for example, when thickened handle thickened processing unit 140, folded-back wall portion 130, the first wall portion 110, unspecified deformation due to thickening processing site adjacent to the thickened section 140 of the second wall portion 120 If the influence of the case or thickening process of the can prevent occurring not occur, can be whether arbitrarily set or brought into close contact with each inner ends of the first wall portion 110 and the second wall portion 120.
[0084]
　In the above embodiment, the thickness of the thickened section 140 has been described for the case of changing gradually in the direction along the closed cross-section, for example, to adjust the shape of the pressing portion D130U of thickening process pressing member D130 it may be set arbitrarily the thickness changing the shape of the thickened section 140 by.
[0085]
　In the above embodiment, the torsion beam manufacturing apparatus 100, the lower fixed mold (second wall-supporting) D110, the upper movable die (first wall-supporting) D120, a punch-type P100, the thickening process a pressing member D130, has been described that includes an upper movable die pressing springs S100, whether provided with a punch-type P100 can be set arbitrarily.
[0086]
　In place of the upper movable mold pressing springs S100, actuators and cam such as a hydraulic cylinder or by combinations thereof, may be configured to be lowered with a delay with respect to the upper movable die D120 the thickening process the pressing member D130 .
　In the above embodiment, by forming a torsion beam element M10 in advance by pressing, after the upper movable mold pressing spring S100 is compressed from the supported by the lower fixed mold D110 and the upper movable mold D120 support portion of the torsion beam material M10 has described the case where the thickness increase process pressing member D130 is thickened process to press the thickened scheduled processing unit M140. However, by applying the upper movable die pressing actuator or a cam mechanism such as a hydraulic cylinder, for example, in place of the spring S100 or the like, and simultaneously thickened processed when being torsion beam material M10 is formed support portions of the torsion beam material M10 is supported it may be configured to start.
[0087]
　Further, the upper movable mold D120 and thickening processes pressing member D130 and configured to be pressed by a hydraulic cylinder, pressing (step S102) and the folded wall portion thickening processing (step S104) and the substantially one step it may be.
　That is, the upper movable die D120, connected to a hydraulic cylinder or the like having a pressing (step S102) possible pressure, has a thickness increase process folding the pressing member D130 wall thickening (step S104) possible pressure as well as connected to a hydraulic cylinder or the like, thereby interlocking the thickening process the pressing member D130 on the movable mold D120. Thus, the upper movable die D120 is pressing a torsion beam element M10 metallic material tube (step S102) and the after subsequently folded wall portion thickening process is the (step S104), and substantially one step (station) in may be produced torsion beam 10.
[0088]
　In the above embodiment, the second wall portion supporting a first wall portion supporting, has been described constituted by a lower fixed mold D110 and the upper movable die D120, die movement direction of the thickening process it can be set arbitrarily.
[0089]
　In the above embodiment includes the torsion beam material support member, a lower fixed mold (second wall-supporting) D110, the upper movable die (first wall-supporting) D120, the punch-type P100 has been described, for example, capable of supporting the chuck device supporting portion, clamps or the like, may be other than a mold.
[0090]
　In this embodiment, a case has been described in which also serves as a press mold that lower fixed mold D110 and the upper movable mold D120 is formed a second wall portion 120 and the first wall portion 110 of the torsion beam material M10, torsion beam material support member or configuring or separately to the press mold and integrally can be set arbitrarily.
[0091]
　In the above embodiment, a metal material tube used for forming the torsion beam material M10 is, the case has been described where a uniform round steel pipe wall thickness, for example, corresponding parts are formed fatigue alleviated thick shape steel or a metal tube welded tube (metal material plate) formed by press forming or roll forming is formed by plastic working, extrusion molding, may be formed using a metal tube formed by a pultrusion.
　Further, in the above embodiment, the metal material pipes used in the production of the torsion beam 10 has been described is a steel tube, it may be applied in addition to the steel pipe.
Example 1
[0092]
　To verify the effect of the torsion beam manufacturing method according to the present invention, it was performed numerical analysis using the torsion beam 1/4 model. In this numerical analysis, a round steel pipe with a strength of 780MPa class and mother tube, the state of being press-molded to the raw tube was analyzed when viewed by 1/4 split plan view of the blank tube . Note that blank tube size, which is added to the press forming of the comparative example and thickness 2.9mm in outer diameter 89.1Mm, wall thickness outside diameter 90mm is intended to apply a torsion beam manufacturing method of the present invention example 2.9mm and the.
[0093]
　As shown in FIG. 11 (A), first, the mother pipe W500, placed between the lower fixed mold D110 and the upper movable mold D120 (hereinafter, referred to as preparation step). Note that in FIG. 11 (A) ~ FIG 11 (C), the lower fixed mold D110 and the upper movable mold D120 shows only pressing surface.
　Subsequently, FIG. 11 (B), the lower the upper movable die D120, pressing a blank tube W500 between the lower fixed mold D110 (hereinafter, referred to as pressing step). In the manufacturing method of the comparative example, since the product shape is determined in this step, torsion beam 500A is completed by directly releasing the next step. On the other hand, in the case of applying the manufacturing method of the present invention embodiment, in addition to the pressing step, as shown in FIGS. 7A ~ Figure 9C, performed thickening process by thickening process pressing member D130, then separated torsion beam 500B is completed by type. In the thickening step, processing crushing 1mm ears in the height direction, i.e. in the direction along the curved surface of the ear portion for machining crushing so as to reduce to about 2 mm. In this case, the added amount of distortion is about 5%.
　In FIG. 11 (B), it is omitted thickening process pressing member D130.
[0094]
　In the case of applying the manufacturing method of the present invention example, the preparation step corresponds to step S101 of FIG. 6, the pressing step corresponds to the step S102, S103, and the thickening process corresponds to step S104 .
[0095]
　The torsion beam 500A of the comparative examples obtained through the steps described above shown in FIG. 12 (A), a torsion beam 500B according to the present invention embodiment shown in FIG. 12 (B). These views 12 (A), in 12 (B), shows that residual stresses deeper portion color is high.
　In the torsion beam 500A of the comparative example shown in FIG. 12 (A), uniformly strong residual stress in almost the entire inner surface of the closed section is left. That is, while acting tensile force on the inner surface of the closed section, the outer surface of the closed section and acts compressive forces, 900 MPa about the residual stress at the maximum is remained as a result.
[0096]
　On the other hand, the torsion beam 500B of the present invention embodiment shown in FIG. 12 (B), not cause large tensile force or compression force in the inner and outer surfaces of the closed section, as a result, the residual stress at the ear portion inner surface below 100MPa , and Otose to 200MPa approximately at most a residual stress at the ear portion outer surface. Moreover, the residual stress of the other portions in addition to a pair of ears is also reduced at the same time.
　As explained above, torsion beam 500B of the present invention embodiment, it was confirmed residual stress compared to the torsion beam 500A of the comparative example can be effectively reduced.
Example 2
[0097]
　As to verify the effect of the torsion beam manufacturing method according to the present invention, a second embodiment of a case of changing the conditions of the thickening process is described. In the following description will focus on differences from the first embodiment, the description thereof is omitted as remaining elements are the same as those in Example 1.
　The thickening process of the second embodiment, processing crushing 3mm ears in the height direction, i.e. in the direction along the curved surface of the ear portion for machining crushing so as to reduce to about 6 mm. In this case, the added amount of distortion is about 15%.
[0098]
　The torsion beam 600B according to the present invention examples obtained through such thickening process shown in FIG. 12 (C). Also in the torsion beam 600B of the present invention embodiment, a large tensile force or compression force is not caused in a pair of ears, and, Drop residual stress. Moreover, the residual stress of the other portions in addition to these ears are also reduced at the same time.
　Or as in the description, in the torsion beam 600B of the present invention embodiment, it was confirmed residual stress compared to the torsion beam 500A of the comparative example can be effectively reduced.
　Also, as can be understood from the results of Example 2, reduction degree of residual stress inside the torsion beam 600B is approximately proportional to the degree of reduction of the residual stress at the outer surface. Thus, by measuring the residual stress in the outer surface of the ear portion, reducing the degree of residual stress in the inner surface of the ear portion can be estimated.
[0099]
　The gist of the embodiments described above are summarized below.
(1) a method torsion beam produced according to the present embodiment, a cross section perpendicular to the longitudinal direction, a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ear portions (a pair of folded wall portions 130) constant producing shaped closed cross-section portion 11, the longitudinal shape changing portion 12 and continuous to the certain shape closed-section portion 11 the shape of the closed cross section changes as the distance from the predetermined shape closed-section portion 11, the torsion beam 10 with a method of, in at least the longitudinal shape changing portion 12, while supporting the both outer side surfaces of each of the pair of ear portions, said pair of ears each to resist bulging of the pair of ear portions the was pressed from the outside with a thickening forming a pair of thickened portion.
　A pair of ears before the thickening step, the residual stress is generated in each unit containing a pair of ears. According to the production method described in above (1), the residual stress in the thickness increasing process, by plastically deforming by pressing from outside a pair of ears, it can be eliminated or reduced. Eliminate or reduce such residual stress is conventionally not obtained form unless special processing such as hydroformed, it takes a great effort. This aspect can be dropped residual stress in a simple press working without requiring such effort.
　Therefore, according to the torsion beam manufacturing method of this embodiment, an excellent torsion beam 10 in fatigue properties can be produced easily and efficiently.
[0100]
(2) In the torsion beam manufacturing method according to the above (1), as described for example with reference to FIG. 7B, in the thickening process, except for the pair of ear portions, the punch-type inner surface of the closed section P100 in the support state, or by pressing the pair of ear portions.
　If according to the above (2), since the portion other than the pair of ear portions can be prevented deformation supported by the punch type P100, the pressing force applied to the pair of ears, a pair of ears it can be concentrated to increase meat processing. As a result, it is possible to more reliably eliminate or reduce the residual stress of each part including a pair of ears.
[0101]
(3) In the torsion beam manufacturing method according to (1) or (2), in the thickening step, the maximum value of the thickness in the thickening section, the plate in the portion other than the thickening portions of the same cross-section thick so that 1.01 to 1.50 times, or by pressing the pair of ear portions.
[0102]
Constant (4) torsion beam manufacturing apparatus according to the present embodiment, a cross section perpendicular to the longitudinal direction, a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ear portions (a pair of folded wall portions 130) producing shaped closed cross-section portion 11, the longitudinal shape changing portion 12 and continuous to the certain shape closed-section portion 11 the shape of the closed cross section changes as the distance from the predetermined shape closed-section portion 11, the torsion beam 10 with an apparatus for the pair of first mold for supporting the both outer surfaces of the ear portions both (lower fixed mold D110 and the upper movable mold D120); the more outward the top of the pair of ear portions both second die for pressing inward the closed surface (thickening process pressing member D130); comprises.
　Prior to thickening processing by torsion beam manufacturing apparatus according to the above (4), the residual stress is generated in each unit including a pair of ears. In the present embodiment, while supporting the both outer surfaces of the pair of ear portions both by the first mold, towards the inside of the closed section from outside the top of the pair of ear portions both by the second mold by plastically deforming by pressing Te, it is possible to eliminate or reduce the residual stress.
　Therefore, according to the torsion beam manufacturing apparatus of the present embodiment, an excellent torsion beam 10 in fatigue properties can be produced easily and efficiently.
[0103]
(5) In the above torsion beam manufacturing apparatus according to (4), of the closed plane, the third mold may further comprise a (punch type P100) for supporting the inner surface excluding the pair of ear portions .
　Above (5), the it is possible to prevent deformation in favor than inner portions other than a pair of ears in the third die, the pressing force applied to the pair of ears, a pair it can be concentrated to increase meat processing ears. As a result, it is possible to more reliably eliminate or reduce the residual stress of each part including a pair of ears.
[0104]
(6) torsion beam 10 according to this embodiment, a cross section perpendicular to the longitudinal direction, certain shapes are closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ear portions (a pair of folded wall portions 130) a closed-section portion 11; and the constant shape closed shape changing portion 12 which continues to the surface portion 11 and the shape of the closed cross section changes as the distance from the predetermined shape closed-section portion 11; wherein at least the shape-changing portion 12 wherein each pair of ears is, without a thickened portion which plate thickness is increased than the portion other than the pair of ears in; the residual stress in the thickest position of the plate thickness of each of thickened portions, the 70% or less of the tensile strength estimated from the Vickers hardness at the outer surface of the thickest position.
　The pair of ears before thickened portion is formed, the residual stress has occurred in each unit containing a pair of ears. However, the torsion beam embodiment described above (6) has been produced by the torsion beam manufacturing apparatus aspects described torsion beam manufacturing method or the aspects described (4) to (1), the above-mentioned reasons residual stress is eliminated or reduced by. Then, the residual stress at the thickest location of the plate thickness of each of thickened portion is equal to or less than 70% of the tensile strength estimated from the Vickers hardness at the outer surface of the thickest position.
　Accordingly, and it has a torsion beam 10 also is easily and efficiently manufactured while excellent fatigue properties.
[0105]
(7) torsion beam 10 according to the above (6), the said thickness at the thickest location, is 1.01 to 1.50 times the thickness of the portion other than the thickening portions of the same cross-section.
Industrial Applicability
[0106]
　The present invention can provide an excellent torsion beam fatigue properties. Further, capable of producing such torsion beam easily and efficiently, it can also provide the torsion beam manufacturing method and torsion beam manufacturing apparatus. Thus, the availability of the industry is large.
DESCRIPTION OF SYMBOLS
[0107]
　　1 torsion beam type rear suspension apparatus (torsion beam suspension
　　apparatus) 2 torsion beam assembly
　　5 trailing arm
　(arm) 10 the torsion beam
　11 fixed shape closed-section portion
　12 longitudinal radius variations (shape change
　unit) 13 mounted closed-section portion
　14 Mounting portion
　100 the torsion beam manufacturing apparatus
　110 first wall portion
　120 and the second wall portion
　130 folded-back wall portion
　131 first wall portion side turn point
　132 second wall portion side turn point
　140 thickening processing unit
　D110 lower fixed mold (second wall-supporting, torsion beam material supporting
　member) D120 upper movable die (first wall-supporting torsion beam material supporting
　member) D130 thickening process pressing member
　M10 torsion beam material
　M130 folded wall portion scheduled portion
　M140 thickening scheduled processing unit

WE CLAIM

Cross section perpendicular to the longitudinal direction, a constant shape closed cross-section portion and the fixed shape closed continuous with the surface portion and the shape of the closed cross section is a closed section of the substantially V-shaped or substantially U-shaped having a pair of ears there a method of manufacturing a torsion beam and a shape change unit that changes with distance from the predetermined shape closed-section portion,
　in a state where at least the shape change unit, supporting the both outer side surfaces of each of the pair of ear portions has a thickness increasing to form by pressing from the outside a pair of thickened portion of the pair of ear portions respectively to resist bulging of the pair of ear portions
torsion beam manufacturing method characterized by.
[Requested item 2]
　In the thickening step, except for the pair of ear portions, while supporting the inner surface of the closed section, the torsion beam method according to claim 1, characterized in that for pressing the pair of ear portions.
[Requested item 3]
　In the thickening step, so that the maximum value of the thickness in the thickening unit, and 1.01 to 1.50 times the thickness in a portion other than the thickening portions of the same cross-section, said pair of ears torsion beam method according to claim 1 or 2, characterized in that for pressing the parts.
[Requested item 4]
　Cross section perpendicular to the longitudinal direction, a constant shape closed cross-section portion and the fixed shape closed continuous with the surface portion and the shape of the closed cross section is a closed section of the substantially V-shaped or substantially U-shaped having a pair of ears there apparatus for producing a torsion beam and a shape change unit that changes with distance from the predetermined shape closed-section portion,
　the first mold and supporting the both outer surfaces of the pair of ear portions both;
　the pair ; the top of the ear portion both towards than outside inward of the closed cross section and the second mold to press the
torsion beam manufacturing apparatus comprising: a.
[Requested item 5]
　Wherein among the closed plane, the torsion beam manufacturing apparatus according to claim 4, further comprising a third die for supporting the inner surface excluding the pair of ear portions.
[Requested item 6]
　Cross section perpendicular to the longitudinal direction, a constant shape closed cross-section portion and a closed cross-section of substantially V-shaped or substantially U-shaped having a pair of ear portions;
　shape of the certain shaped closed continuous to face and the closed section ; but the a constant shape closed shape changing unit that changes with distance from the surface
provided with,
　increasing the pair of ear portions, respectively, in at least the shape change unit, the plate thickness than the portion other than the pair of ear portions has increased No meat portion;
　residual stress in the thickest location of the thickness of each of thickened portion, is 70% of the tensile strength below estimated from Vickers hardness at the outer surface of the thickest position;
characterized in that torsion beam to be.
[Requested item 7]
　Torsion beam according to claim 6, wherein said plate thickness at the thickest location, characterized in that 1.01 to 1.50 times the thickness of the portion other than the thickening portions of the same cross-section.