STABILIZER MANUFACTURING DEVICE AND STABILIZER MANUFACTURING METHOD

Abstract

According to one embodiment, a stabilizer manufacturing device includes a first forming unit (31) and a second forming unit (32). The first forming unit (31) includes a first forming mandrel (61), a clamping member (62)(63), and a first bending roll (65). The first forming mandrel (61) includes a first forming portion (70) that is arc-shaped when viewed from above, and a support portion (71)(72) that supports a workpiece. The first bending roll (65) moves along the first forming portion (70). The second forming unit (32) includes a second forming mandrel (161), a clamping member (162)(163), and a second bending roll (165). The second forming mandrel (161) includes a second forming portion (170) that is arc-shaped when viewed from above, and a support portion (171) (172) that holds the workpiece.The second bending roller (165) moves along the second forming portion (170).

Description

Stabilizer manufacturing device and stabilizer manufacturing method

[0001] The present invention relates to a manufacturing apparatus for manufacturing a stabilizer for a vehicle, for example, and a manufacturing method for the stabilizer.

[0002] A stabilizer disposed in a suspension mechanism of a vehicle has a torsion section extending in the width direction of the vehicle, a pair of arm sections connected to both ends of the torsion section, and a plurality of bent sections, etc. In one example of the suspension mechanism, the torsion section is supported by the vehicle body, and the arm sections are connected to a suspension arm or the like.

[0003] To manufacture stabilizers made of materials such as steel rods or pipes, heated materials are bent into a desired shape. In one example of a solid stabilizer, the material is heated to a high temperature (e.g., 960°C or higher) and the portion to be bent is pressed and bent using a die. However, scratches may be formed on the surface of the stabilizer where the die comes into contact with the material. Furthermore, because the material is heated to a high temperature, scaling may occur on the surface of the material. Pressing and bending a material with scale adhesion using a die can undesirably cause so-called scale scratches in the areas where the scale had adhered. Furthermore, maintaining the material at a high temperature for a long period of time can cause decarburization, which is also a problem.

[0004] In the case of a hollow stabilizer, a pipe bender may be used, as shown in, for example, Japanese Patent Laid-Open Publication No. 2004-9125 (Patent Document 1). In one example of a pipe bender, a material is bent using a roller while being pulled.

[0005] Japanese Patent Application Laid-Open No. 2004-9125 International Publication WO2011 / 029434

[0006] However, pipe bending can sometimes cause problems with the cross-sectional shape of the bent portion. It has also been considered to use a mold instead of a pipe bender to bend the material. However, bending the material using a mold not only damages the surface of the material, but can also result in a flattened cross-section of the bent portion. International Publication WO 2011 / 029434 (Patent Document 2) has also proposed placing molten material in a mold cavity and hardening the material inside the mold. However, this method cannot be used to manufacture steel stabilizers.

[0007] An object of the present invention is to provide a stabilizer manufacturing apparatus and a stabilizer manufacturing method that can bend a bent portion without damaging the surface of the stabilizer.

[0008] A stabilizer manufacturing apparatus according to one embodiment includes a first forming unit and a second forming unit. The first forming unit includes a first forming mandrel, a first front holding member, a first rear holding member, and a first bending roller. The first forming mandrel includes a first forming portion having an arc shape when viewed from above, a front support portion that supports a workpiece between the first front holding member and the first forming mandrel, and a rear support portion that supports the workpiece between the first rear holding member and the first forming mandrel. When bending the workpiece in a first direction, the workpiece is clamped between the first front holding member and the first forming mandrel. Also, the workpiece is clamped between the second front holding member and the second forming mandrel. When bending the workpiece in a second direction, the workpiece is clamped between the first rear holding member and the first forming mandrel. Also, the workpiece is clamped between the second rear holding member and the second forming mandrel. The first bending roller rotates along the first forming portion, and the second bending roller rotates along the second forming portion.

[0009] In this specification, the front side of the forming mandrel refers to the side on which the workpiece is placed relative to the forming mandrel when bending the workpiece in a first direction, and the rear side of the forming mandrel refers to the side on which the workpiece is placed relative to the forming mandrel when bending the workpiece in a second direction.

[0010] The second forming unit includes a second forming core, a second front holding member, a second rear holding member, and a second bending roller. The second forming core has a second forming portion that is arc-shaped when viewed from above, a front support portion that supports the workpiece between itself and the second front holding member, and a rear support portion that supports the workpiece between itself and the second rear holding member.

[0011] The first and second forming cores may be bilaterally symmetrical to each other, and the first and second forming units may be movable along guide members extending horizontally, and may include a first unit drive mechanism for moving the first forming unit and a second unit drive mechanism for moving the second forming unit.

[0012] In the stabilizer manufacturing apparatus of this embodiment, the first molding section may have a large-diameter arcuate surface with a first radius of curvature and a small-diameter arcuate surface with a second radius of curvature smaller than the first radius of curvature, and the second molding section may have a large-diameter arcuate surface with the first radius of curvature and a small-diameter arcuate surface with the second radius of curvature. The stabilizer manufacturing apparatus of this embodiment is configured so that the first molding core and the second molding core are each movable in the vertical direction. The stabilizer manufacturing apparatus is further equipped with a first elevating mechanism that moves the first molding core so that the large-diameter arcuate surface or the small-diameter arcuate surface of the first molding core is flush with the first bending roller. The stabilizer manufacturing apparatus is also further equipped with a second elevating mechanism that moves the second molding core so that the large-diameter arcuate surface or the small-diameter arcuate surface of the second molding core is flush with the second bending roller.

[0013] In one embodiment of a method for manufacturing a stabilizer, a steel workpiece, which is the material for the stabilizer, is heated to a temperature suitable for warm working (below point A1). The heated workpiece is set on a forming mandrel having an arc-shaped forming portion, and the workpiece is fixed to the forming mandrel with a pressing member. The forming portion includes a plurality of arc surfaces each having a different radius of curvature. A rotatable bending roller is moved along a selected arc surface from the plurality of arc surfaces, thereby bending the workpiece to a radius of curvature corresponding to the selected arc surface. The bent workpiece is then reheated to a temperature at which hardening is possible, for example, by electrical heating (or a furnace), and the reheated workpiece is quenched by being placed in a coolant (e.g., water) to cool. The coolant may be oil or another fluid.

[0014] According to the stabilizer manufacturing apparatus and manufacturing method of this embodiment, stabilizers having a plurality of bent portions each having a different radius of curvature can be efficiently manufactured. Moreover, roll bending is performed in the warm region below point A1 using a forming mandrel having an arcuate surface and a bending roller. This avoids problems such as scaling and decarburization on the surface of the stabilizer, and prevents the occurrence of so-called scale defects. Moreover, compared to cold forming, deformation resistance is smaller, and bent portions with high shape accuracy can be formed relatively easily.

[0015] 1 is a perspective view showing a portion of a vehicle and a stabilizer. FIG. 2 is a plan view showing an example of a stabilizer. FIG. 3 is a front view of the stabilizer shown in FIG. 2. FIG. 4 is a side view of the stabilizer shown in FIG. 2. FIG. 5 is a diagram showing an example of a manufacturing process for a stabilizer. FIG. 6 is a front view of a stabilizer manufacturing apparatus according to one embodiment. FIG. 7 is a plan view of the stabilizer manufacturing apparatus. FIG. 8 is an enlarged plan view of a portion of the stabilizer manufacturing apparatus. FIG. 9 is an enlarged front view of a portion of the stabilizer manufacturing apparatus. FIG. 10 is a plan view schematically showing a portion of the stabilizer manufacturing apparatus and a workpiece. FIG. 11 is a plan view schematically showing a portion of the stabilizer manufacturing apparatus and the workpiece on which the first bent portion and the second bent portion have been formed. FIG. 12 is a plan view schematically showing a portion of the stabilizer manufacturing apparatus and the workpiece that has been moved. FIG. 13 is a plan view schematically showing a portion of the stabilizer manufacturing apparatus and the workpiece on which the third bent portion and the fourth bent portion have been formed. 1A and 1B are plan views schematically showing a part of the stabilizer manufacturing apparatus and the workpiece on which the fifth bent portion has been formed. 2A and 2B are plan views schematically showing a part of the stabilizer manufacturing apparatus and the workpiece on which the seventh bent portion has been formed. 3A and 3B are plan views schematically showing a part of the stabilizer manufacturing apparatus and the workpiece on which the sixth bent portion has been formed. 4A and 4B are plan views schematically showing a part of the stabilizer manufacturing apparatus and the workpiece on which the eighth bent portion has been formed.

[0016] A stabilizer manufacturing apparatus and a stabilizer manufacturing method according to one embodiment will be described below with reference to FIGS. 1 to 16. FIG. 1 shows a portion of a vehicle 11 equipped with a stabilizer 10. The stabilizer 10 is disposed in a suspension mechanism 12 of the vehicle 11. The stabilizer 10 includes a torsion portion 15 extending in the width direction of the vehicle body 13 (the direction indicated by the double-headed arrow Y in FIG. 1), and a pair of arm portions 16 and 17 connected to both ends of the torsion portion 15. Eye portions 18 and 19 are formed at the tips of the arm portions 16 and 17, respectively.

[0017] The torsion section 15 is supported on a part of the vehicle body 13 via a pair of support sections 20, 21 equipped with rubber bushings or the like. The eye sections 18, 19 are connected to the suspension arms of the suspension mechanism section 12 via link members 22, 23, respectively. When the vehicle 11 travels around a curve, loads of opposite phases are input to the arm sections 16, 17. This applies a bending force to the arm sections 16, 17 and twists the torsion section 15, thereby suppressing rolling of the vehicle body 13.

[0018] FIG. 2 is a plan view showing an example of the stabilizer 10. FIG. 3A is a front view of the stabilizer 10, and FIG. 3B is a side view of the stabilizer 10. The material of the stabilizer 10 (hereinafter referred to as the workpiece W) is made of steel (e.g., low-carbon steel) whose strength can be improved by heat treatment such as quenching. An example of low-carbon steel is SAE15B26, which complies with the standards of the U.S. Society of Automotive Engineers (SAE). The workpiece W may be solid or hollow. The stabilizer 10 may have one or more bent portions formed in each of the arm portions 16 and 17, including a three-dimensionally bent shape. Alternatively, the torsion portion 15 may have two or more bent portions along its longitudinal direction. In this specification, the line segment X2 extending in the longitudinal direction of the stabilizer 10 (workpiece W) in FIG. 2 is referred to as the axis X2 of the workpiece W.

[0019] The shape of the stabilizer 10 is not limited to the example shown in Fig. 2. The stabilizer 10 shown in Fig. 2 is bilaterally symmetrical with respect to the center in the longitudinal direction as the axis of symmetry X1. One example of the stabilizer 10 has, in order from the positions closest to the eye portions 18, 19, a pair of first and second bent portions R1 and R2, a pair of third and fourth bent portions R3 and R4, a pair of fifth and sixth bent portions R5 and R6, and a pair of seventh and eighth bent portions R7 and R8.

[0020] FIG. 4 shows the manufacturing process of the stabilizer 10 according to this embodiment. In the heating step ST1 shown in FIG. 4, the workpiece W, which is the material of the stabilizer 10, is heated to a temperature suitable for warm forming. The heating temperature is, for example, 400°C or higher, with the upper limit being a temperature not exceeding the A1 point (723°C) of the steel. In the case of a solid workpiece, the workpiece is heated to, for example, 600°C. In the case of a hollow workpiece, the workpiece is preferably heated to a warm range (a temperature lower than the austenitizing temperature of steel) of, for example, 700°C or lower. Heating in the warm range is preferable because it does not substantially produce scale, decarburization, or the like on the surface of the workpiece W. One example of a heating means is a heating furnace in which the workpiece is heated while being moved by a walking beam. However, resistance heating or high-frequency induction heating may also be used as the heating means.

[0021] The workpiece W heated to a temperature suitable for warm forming is formed into a predetermined stabilizer shape in the forming step ST2 in Fig. 4. In the forming step ST2, the workpiece W is bent (roll-bent) using a stabilizer manufacturing apparatus 25 (shown in Figs. 5 to 16), which will be described in detail below. The workpiece W handled in the forming step ST2 has been heated to a temperature suitable for warm forming (lower than point A1), and therefore has a hardness that makes plastic processing easier than when it is cold (at room temperature).

[0022] In the eye-forming step ST3, the eye portions 18, 19 are bent at predetermined angles (indicated by θ1 and θ2 in FIG. 2) by a press-bending die while the temperature of the workpiece W is maintained in the warm range. It goes without saying that the shapes and angles θ1 and θ2 of the eye portions 18, 19 are not limited to the examples shown in FIG. 2 and FIG. 3A and FIG. 3B, and may be implemented in various ways.

[0023] In the reheating step ST4 in FIG. 4, the workpiece W is heated to a temperature at which quenching is possible (for example, 910-980°C ± 30°C), i.e., a temperature above the A3 transformation point. The heated workpiece W is quenched using a coolant in the quenching step ST5. For quenching, the workpiece W, which has been kept at a temperature at which quenching is possible, is immersed, for example, in a water tank and rapidly cooled. The cooling rate of the workpiece W is set to a temperature gradient at which a quenched structure (martensite) is formed in the workpiece W. Since water quenching is performed here, it is relatively safe compared to oil quenching. Note that oil or other fluids may be used as the coolant.

[0024] The stabilizer manufacturing apparatus 25 used in the forming process ST2 will be described below with reference to Figs. 5 to 16. Fig. 5 is a front view of the stabilizer manufacturing apparatus 25, and Fig. 6 is a plan view of the stabilizer manufacturing apparatus 25. Fig. 7 is a plan view of an enlarged portion of the stabilizer manufacturing apparatus 25, and Fig. 8 is a front view of an enlarged portion of the stabilizer manufacturing apparatus 25.

[0025] 5 and 6, the stabilizer manufacturing apparatus 25 includes a base 30 installed on the floor of a factory or the like, a first forming unit 31 and a second forming unit 32 mounted on the base 30, and a robot 33 provided near the base 30. The first forming unit 31 and the second forming unit 32 are substantially bilaterally symmetrical to each other. The robot 33 has a robot arm 34. A holding unit 35 equipped with a chuck or the like capable of holding a workpiece W is provided at the tip of the robot arm 34.

[0026] The workpiece W held by the holder 35 can be moved to a desired position by the robot arm 34. The example of the stabilizer 10 shown in FIG. 3B has a bent portion that bends at an angle α when viewed from the side. Therefore, the robot arm 34 rotates the workpiece W around the axis X2 (the direction indicated by θ3 in FIGS. 2 and 3B) depending on the direction in which the workpiece W is to be bent. This allows the subsequent bending process to form bent portions that are three-dimensionally bent in different directions.

[0027] The base 30 has guide members 41, 42, 43, and 44 (shown in FIG. 6) extending horizontally. The first molding unit 31 can move horizontally along the guide members 41 and 42. The second molding unit 32 can move horizontally along the guide members 43 and 44. The first molding unit 31 and the second molding unit 32 are arranged so that they can move toward and away from each other on the same straight line.

[0028] 6, the stabilizer manufacturing apparatus 25 includes a first unit drive mechanism 51 for moving the first forming unit 31 and a second unit drive mechanism 52 for moving the second forming unit 32. The first unit drive mechanism 51 and the second unit drive mechanism 52 can change the distance between the first forming unit 31 and the second forming unit 32. One example of the unit drive mechanisms 51 and 52 is a servo motor and a ball screw, each of which can move the forming units 31 and 32 to predetermined positions.

[0029] First, the first shaping unit 31 shown on the right side of Fig. 7 will be described. The first shaping unit 31 has a first movable frame 60 (shown in Fig. 6) that moves along the guide members 41, 42, a first shaping core 61, a first front pressing member 62, a first rear pressing member 63, and a first bending roller mechanism 64. The first bending roller mechanism 64 includes a rotatable first bending roller 65 and an actuator 66 that moves the first bending roller 65 toward the shaping core 61. A groove 65a corresponding to the diameter of the workpiece W is formed on the circumferential surface of the first bending roller 65.

[0030] The first forming core 61 is fixed to the first movable frame 60 by bolts 67 and 68. As shown in FIG. 7 , the first forming core 61 has a first forming portion 70 that is arc-shaped (almost semicircular) when viewed from above, a front support portion 71, and a rear support portion 72. The front support portion 71 and the rear support portion 72 are each substantially straight and parallel to each other. As will be described in detail later, the front support portion 71 supports a surface W1 of the workpiece W between itself and the first front holding member 62 when the workpiece W is bent in a first direction (indicated by arrow F1 in FIG. 10 ). The first rear support portion 72 supports a surface W2 of the workpiece W between itself and the first rear holding member 63 when the workpiece W is bent in a second direction (indicated by arrow F2 in FIG. 12 ).

[0031] The first bending roller 65 can be moved by an actuator 66 in a direction toward or away from the forming portion 70 of the first forming core 61. The first bending roller 65 revolves along the arc-shaped first forming portion 70, as shown by the double-headed arrow Z1 in Figure 7. That is, the first bending roller 65 revolves within a range of approximately 180° around the center C1 of the first forming portion 70 by a first revolving mechanism 75 (part of which is shown in Figure 5). The height of the first bending roller 65 is constant.

[0032] 7, the arc-shaped first forming portion 70 has a large-diameter arc surface 70a with a first radius of curvature r1, a small-diameter arc surface 70b with a second radius of curvature r2 smaller than the first radius of curvature r1, and a smallest arc surface 70c with an even smaller radius of curvature than the second radius of curvature r2. The large-diameter arc surface 70a is used when bending a bent portion with a large radius of curvature (e.g., bent portion R5). The small-diameter arc surface 70b is used when bending a bent portion with a small radius of curvature (e.g., bent portions R1, R3, R7). The smallest arc surface 70c is used when bending a bent portion with an even smaller radius of curvature.

[0033] The molding portion 70 of this embodiment has three types of arcuate surfaces 70a, 70b, and 70c with different radii of curvature. However, it is sufficient to have arcuate surfaces with at least two types of radii of curvature. In some cases, it may have arcuate surfaces with four or more types of radii of curvature.

[0034] 7 and 8, the front support portion 71 of the first forming core 61 includes a lower support surface 71a, an intermediate support surface 71b, and an upper support surface 71c. The lower support surface 71a is continuous with the large-diameter arcuate surface 70a and extends horizontally. The intermediate support surface 71b is continuous with the small-diameter arcuate surface 70b and extends horizontally. The upper support surface 71c is continuous with the smallest arcuate surface 70c and extends horizontally. Grooves corresponding to the diameter of the workpiece W are formed in each of these support surfaces 71a, 71b, and 71c.

[0035] 8, the first front pressing member 62 includes a lower pressing surface 62a, a middle pressing surface 62b, and an upper pressing surface 62c. The lower pressing surface 62a faces the lower support surface 71a and extends horizontally. The middle pressing surface 62b faces the middle support surface 71b and extends horizontally. The upper pressing surface 62c faces the upper support surface 71c and extends horizontally.

[0036] The lower pressing surface 62a is at the same height as the large-diameter arcuate surface 70a. The intermediate pressing surface 62b is at the same height as the small-diameter arcuate surface 70b. The upper pressing surface 62c is at the same height as the smallest arcuate surface 70c. Grooves corresponding to the diameter of the workpiece W are formed in each of these pressing surfaces 62a, 62b, and 62c. The distance from the lower support surface 71a to the lower pressing surface 62a, the distance from the intermediate support surface 71b to the intermediate pressing surface 62b, and the distance from the upper support surface 71c to the upper pressing surface 62c are all equal to one another.

[0037] 7 and 8, the rear support portion 72 of the first forming core 61 also includes a lower support surface 72a, an intermediate support surface 72b, and an upper support surface 72c. The lower support surface 72a is continuous with the large-diameter arcuate surface 70a and extends horizontally. The intermediate support surface 72b is continuous with the small-diameter arcuate surface 70b and extends horizontally. The upper support surface 72c is continuous with the smallest arcuate surface 70c and extends horizontally. Grooves corresponding to the diameter of the workpiece W are formed in each of these support surfaces 72a, 72b, and 72c.

[0038] 8, the first rear pressing member 63 includes a lower pressing surface 63a, a middle pressing surface 63b, and an upper pressing surface 63c. The lower pressing surface 63a faces the lower support surface 72a and extends horizontally. The middle pressing surface 63b faces the middle support surface 72b and extends horizontally. The upper pressing surface 63c faces the upper support surface 72c and extends horizontally.

[0039] The lower pressing surface 63a is at the same height as the large-diameter arcuate surface 70a. The intermediate pressing surface 63b is at the same height as the small-diameter arcuate surface 70b. The upper pressing surface 63c is at the same height as the smallest arcuate surface 70c. Grooves corresponding to the diameter of the workpiece W are formed in each of these pressing surfaces 63a, 63b, and 63c. The distance from the lower support surface 72a to the lower pressing surface 63a, the distance from the intermediate support surface 72b to the intermediate pressing surface 63b, and the distance from the upper support surface 72c to the upper pressing surface 63c are all equal to one another.

[0040] The first molding unit 31 has a first front actuator 80 for driving the first front holding member 62 and a first rear actuator 81 for driving the first rear holding member 63. The first front holding member 62 and the first rear holding member 63 can be simultaneously moved toward the first molding core 61 in synchronization with each other by the actuators 80, 81.

[0041] The workpiece W can be clamped between the front support portion 71 of the first forming core 61 and the first front holding member 62. The workpiece W can be clamped between the rear support portion 72 of the first forming core 61 and the first rear holding member 63. An example of the actuators 80, 81 is a hydraulic cylinder, but other drive sources (for example, electric actuators such as servo motors) may also be used.

[0042] The first molding core 61, the first front holding member 62, and the first rear holding member 63 can be moved up and down (indicated by the double-headed arrow Z3 in FIG. 8) by a first lifting mechanism 86 (shown in FIG. 5). An example of a drive source for the first lifting mechanism 86 is an electric actuator such as a servo motor, but other drive sources (for example, a hydraulic cylinder) may also be used.

[0043] By moving the first forming core metal 61 up and down by the first lifting mechanism 86, the large-diameter arcuate surface 70a, the small-diameter arcuate surface 70b, or the smallest arcuate surface 70c can be moved to the same height as the first bending roller 65. Figure 8 shows a state in which the smallest arcuate surface 70c has moved to the same height as the first bending roller 65.

[0044] Next, the second shaping unit 32 shown on the left side of Fig. 7 will be described. The second shaping unit 32 has a second movable frame 160 (shown in Fig. 6) that moves along the guide members 43, 44, a second shaping core 161, a second front pressing member 162, a second rear pressing member 163, and a second bending roller mechanism 164. The second bending roller mechanism 164 includes a rotatable second bending roller 165 and an actuator 166 that moves the second bending roller 165 toward the shaping core 161. A groove 165a corresponding to the diameter of the workpiece W is formed on the circumferential surface of the second bending roller 165.

[0045] The second forming core 161 is fixed to the second movable frame 160 by bolts 167 and 168. As shown in FIG. 7 , the second forming core 161 has a second forming portion 170 that is arc-shaped (almost semicircular) when viewed from above, a front support portion 171, and a rear support portion 172. The front support portion 171 and the rear support portion 172 are each substantially straight and parallel to each other. As will be described in detail later, the front support portion 171 supports a surface W1 of the workpiece W between itself and the second front holding member 162 when the workpiece W is bent in a first direction (indicated by arrow F1 in FIG. 10 ). The rear support portion 172 supports a surface W2 of the workpiece W between itself and the second rear holding member 163 when the workpiece W is bent in a second direction (indicated by arrow F2 in FIG. 12 ).

[0046] The second bending roller 165 can be moved toward or away from the forming portion 170 of the second forming core 161 by an actuator 166. The second bending roller 165 revolves along the arc-shaped second forming portion 170, as shown by the double-headed arrow Z2 in Figure 7. That is, the second bending roller 165 revolves within a range of approximately 180° around the center C2 of the second forming portion 170 by a second revolving mechanism 175 (part of which is shown in Figure 6). The height of the second bending roller 165 is constant.

[0047] 7, the arc-shaped second forming portion 170 has a large-diameter arc surface 170a with a first radius of curvature r1, a small-diameter arc surface 170b with a second radius of curvature r2 smaller than the first radius of curvature r1, and a smallest arc surface 170c with an even smaller radius of curvature than the second radius of curvature r2. The large-diameter arc surface 170a is used when bending a bent portion with a large radius of curvature (e.g., bent portion R6). The small-diameter arc surface 170b is used when bending a bent portion with a small radius of curvature (e.g., bent portions R2, R4, R8). The smallest arc surface 170c is used when bending a bent portion with an even smaller radius of curvature.

[0048] The molding portion 170 of this embodiment has three types of arcuate surfaces 170a, 170c, and 170b with different radii of curvature. However, it is sufficient to have arcuate surfaces with at least two types of radii of curvature. In some cases, it may have arcuate surfaces with four or more types of radii of curvature.

[0049] As shown in Figure 7, the front support portion 171 of the second forming core 161 includes a lower support surface 171a, an intermediate support surface 171b, and an upper support surface 171c. The lower support surface 171a is continuous with the large-diameter arcuate surface 170a and extends horizontally. The intermediate support surface 171b is continuous with the small-diameter arcuate surface 170b and extends horizontally. The upper support surface 171c is continuous with the smallest arcuate surface 170c and extends horizontally. Grooves corresponding to the diameter of the workpiece W are formed in each of these support surfaces 171a, 171b, and 171c. Note that the second front holding member 162 has a structure common to the first front holding member 62, and therefore a description thereof will be omitted.

[0050] As shown in Figure 7, the rear support portion 172 of the second forming core metal 161 includes a lower support surface 172a, an intermediate support surface 172b, and an upper support surface 172c. The lower support surface 172a is continuous with the large-diameter arcuate surface 170a and extends horizontally. The intermediate support surface 172b is continuous with the small-diameter arcuate surface 170b and extends horizontally. The upper support surface 172c is continuous with the smallest arcuate surface 170c and extends horizontally. Grooves corresponding to the diameter of the workpiece W are formed in each of these support surfaces 172a, 172b, and 172c. Note that the second rear holding member 163 has a structure common to the first rear holding member 63, and therefore a description thereof will be omitted.

[0051] The second molding unit 32 has a second front actuator 180 for driving the second front holding member 162 and a second rear actuator 181 for driving the second rear holding member 163. The second front holding member 162 and the second rear holding member 163 can be simultaneously moved toward the second molding core metal 161 in synchronization with each other by the actuators 180 and 181.

[0052] The workpiece W can be clamped between the front support portion 171 of the second forming core metal 161 and the second front holding member 162. The workpiece W can be clamped between the rear support portion 172 of the second forming core metal 161 and the second rear holding member 163. An example of the actuators 180, 181 is a hydraulic cylinder, but other drive sources (for example, electric actuators such as servo motors) may also be used.

[0053] The second forming core 161, the second front pressing member 162, and the second rear pressing member 163 can be moved up and down by a second lifting mechanism. The second lifting mechanism has the same structure as the first lifting mechanism 86. By moving the second forming core 161 up and down by the second lifting mechanism, the large diameter arcuate surface 170a, the small diameter arcuate surface 170b, or the smallest arcuate surface 170c can be moved to the same height as the second bending roller 165.

[0054] In the previous process (positioning process), the workpiece W is placed (positioned) at a predetermined position facing a predetermined direction. When bending the workpiece W in a first direction (indicated by arrow F1 in FIG. 10 ), the robot arm 34 sets the workpiece W positioned in the positioning process directly in front of the forming mandrels 61, 161. When bending the workpiece W in a second direction (indicated by arrow F2 in FIG. 12 ), the robot arm 34 sets the workpiece W behind the forming mandrels 61, 161.

[0055] The process of bending the bent portions R1-R8 of the workpiece W using the stabilizer manufacturing apparatus 25 will be described below with reference to FIGS. 9 to 16. FIGS. 9 and 10 show the case where the first bent portion R1 and the second bent portion R2 are bent. The first forming core bar 61 has been moved to a position corresponding to the first bent portion R1. The second forming core bar 161 has been moved to a position corresponding to the second bent portion R2. The first forming core bar 61 and the second forming core bar 161 are spaced apart by a distance L1. The workpiece W is substantially straight. In this case, the small-diameter arcuate surfaces 70b and 170b are selected and used in the bending process.

[0056] 9, the first front pressing member 62 is spaced apart from the front support portion 71 of the first forming core bar 61. The first rear pressing member 63 is spaced apart from the rear support portion 72 of the first forming core bar 61. The first forming core bar 61 has moved to a position where the small-diameter arcuate surface 70b is at the same height as the first bending roller 65.

[0057] The second front pressing member 162 is spaced apart from the front support portion 171 of the second forming core bar 161. The second rear pressing member 163 is spaced apart from the rear support portion 172 of the second forming core bar 161. The second forming core bar 161 has moved to a position where the small diameter arcuate surface 170b is at the same height as the second bending roller 165. The first bending roller 65 and the second bending roller 165 have retracted to positions where they will not interfere with the workpiece W. In this state, the robot arm 34 positions the workpiece W in front of the forming core bars 61, 161.

[0058] 10, the first front holding member 62 moves in the direction indicated by arrow P1, whereby the workpiece W is clamped by the first front holding member 62 and the first forming core bar 61. At the same time, the first rear holding member 63 moves in the direction indicated by arrow P2. The first rear holding member 63 comes into contact with the first forming core bar 61, thereby supporting the first forming core bar 61 from the rear side.

[0059] Furthermore, as the second front holding member 162 moves in the direction indicated by arrow P1, the workpiece W is clamped by the second front holding member 162 and the second forming core bar 161. At the same time, the second rear holding member 163 moves in the direction indicated by arrow P2. As the second rear holding member 163 comes into contact with the second forming core bar 161, the second forming core bar 161 is supported from the rear side.

[0060] In this way, since the load is applied from both the front and rear sides of the first molding core bar 61, it is possible to prevent a large clamp load from being applied unevenly to one side of the first molding core bar 61. As a result, an excessive load is not applied to the first molding core bar 61 or the bolts 67, 68, and it is also possible to prevent the first molding core bar 61 from shifting out of position. Since the load is also applied to the second molding core bar 161 from both the front and rear sides, it is possible to prevent a large clamp load from being applied unevenly to one side of the second molding core bar 161. As a result, an excessive load is not applied to the second molding core bar 161 or the bolts 167, 168, and it is also possible to prevent the second molding core bar 161 from shifting out of position.

[0061] 10, the first bending roller 65 moves along the small-diameter arcuate surface 70b of the first forming core 61, bending the eye 18 side of the workpiece W in the first direction F1 to form a first bent portion R1. At the same time, the second bending roller 165 moves along the small-diameter arcuate surface 170b of the second forming core 161, bending the eye 19 side of the workpiece W in the first direction F1 to form a second bent portion R2.

[0062] 11 and 12 show the case where the third bent portion R3 and the fourth bent portion R4 are bent. The first molding core bar 61 is moved to a position corresponding to the third bent portion R3. The second molding core bar 161 is moved to a position corresponding to the fourth bent portion R4. The distance between the first molding core bar 61 and the second molding core bar 161 is changed to L2.

[0063] As shown in FIG. 11 , the first rear pressing member 63 is spaced apart from the first forming mandrel 61. The second rear pressing member 163 is also spaced apart from the second forming mandrel 161. In this state, the robot arm 34 sets the workpiece W behind the forming mandrels 61, 161. At this time, the robot arm 34 rotates and positions the workpiece W about the axis X2 according to the bending direction of the bent portions R3, R4 (for example, the angle α shown in FIG. 3B ). This allows the bent portions R3, R4 to bend in a direction (three-dimensional direction) different from the bent portions R1, R2. Similarly, the other bent portions R5-R8 can be bent in the desired direction by rotating the workpiece W about the axis X2 by the robot arm 34.

[0064] 12 , the first front holding member 62 moves in the direction indicated by arrow P1, thereby supporting the front side of the first forming core metal 61. At the same time, the first rear holding member 63 moves in the direction indicated by arrow P2, thereby clamping the workpiece W between the first rear holding member 63 and the first forming core metal 61.

[0065] Furthermore, the second front pressing member 162 moves in the direction indicated by arrow P1, thereby supporting the front side of the second forming core metal 161. At the same time, the second rear pressing member 163 moves in the direction indicated by arrow P2, thereby clamping the workpiece W between the second rear pressing member 163 and the second forming core metal 161.

[0066] 12, the first bending roller 65 moves along the small-diameter arcuate surface 70b of the first forming core 61, bending the eye 18 side of the workpiece W in the second direction F2 to form a third bent portion R3. At the same time, the second bending roller 165 moves along the small-diameter arcuate surface 170b of the second forming core 161, bending the eye 19 side of the workpiece W in the second direction F2 to form a fourth bent portion R4.

[0067] The fifth bending portion R5 and the sixth bending portion R6 are located close to each other. The seventh bending portion R7 and the eighth bending portion R8 are also located close to each other. Therefore, if the fifth bending portion R5 and the sixth bending portion R6 are bent simultaneously, there is a risk that the first forming unit 31 and the second forming unit 32 will interfere with each other. Furthermore, if the seventh bending portion R7 and the eighth bending portion R8 are bent simultaneously, there is a risk that the first forming unit 31 and the second forming unit 32 will interfere with each other. For this reason, in this embodiment, when bending the bending portions R5, R6, R7, and R8 that are located close to each other, each bending process is performed separately.

[0068] FIG. 13 shows the bending of the fifth bent portion R5. The first forming core 61 is moved to a position corresponding to the fifth bent portion R5. In this case, the large-diameter arcuate surface 70a is selected and used in the bending process. Therefore, the large-diameter arcuate surface 70a of the first forming core 61 faces the first bending roller 65. The workpiece W is clamped by the first front pressing member 62 and the first forming core 61. At the same time, the first rear pressing member 63 abuts against the first forming core 61, thereby supporting the first core 61 from the rear side. In this state, the first bending roller 65 moves along the large-diameter arcuate surface 70a of the first forming core 61, bending the eye portion 18 side of the workpiece W in the first direction F1, thereby forming the fifth bent portion R5.

[0069] 14 shows the case where the seventh bent portion R7 is bent. The workpiece W is moved to the rear side of the first forming core 61 by the robot arm 34. The first forming core 61 is moved to a position corresponding to the seventh bent portion R7. In this case, the small-diameter arcuate surface 70b is selected and used in the bending process. Therefore, the small-diameter arcuate surface 70b of the first forming core 61 faces the first bending roller 65.

[0070] 14, the workpiece W is clamped by the first rear pressing member 63 and the first forming core 61. At the same time, the first front pressing member 62 comes into contact with the first forming core 61, thereby supporting the first forming core 61 from the front side. In this state, the first bending roller 65 moves along the small-diameter arc surface 70b of the first forming core 61, and the eye portion 18 side of the workpiece W is bent in the second direction F2, thereby forming a seventh bent portion R7.

[0071] 15 shows the case where the sixth bending portion R6 is bent. The workpiece W is moved to the front side of the second forming core bar 161 by the robot arm. The second forming core bar 161 is moved to a position corresponding to the sixth bending portion R6. In this case, the large-diameter arcuate surface 170a is selected and used in the bending process. Therefore, the large-diameter arcuate surface 170a of the second forming core bar 161 faces the second bending roller 165. The workpiece W is clamped by the second front pressing member 162 and the second forming core bar 161. At the same time, the second rear pressing member 163 abuts against the second forming core bar 161, thereby supporting the second core bar 161 from the rear side. In this state, the second bending roller 165 moves along the large-diameter arc surface 170a of the second forming core metal 161, and the eye portion 19 side of the workpiece W is bent in the first direction F1, thereby forming the sixth bent portion R6.

[0072] 16 shows the case where the eighth bent portion R8 is bent. The workpiece W is moved to the rear side of the second forming core 161 by the robot arm. The second forming core 161 is moved to a position corresponding to the eighth bent portion R8. In this case, the small-diameter arcuate surface 170b is selected and used in the bending process. Therefore, the small-diameter arcuate surface 170b of the second forming core 161 faces the second bending roller 165.

[0073] The workpiece W is clamped by the second rear pressing member 163 and the second forming core metal 161. At the same time, the second front pressing member 162 comes into contact with the second forming core metal 161, thereby supporting the second forming core metal 161 from the front side. In this state, the second bending roller 165 moves along the small-diameter arc surface 170b of the second forming core metal 161, and the eye portion 19 side of the workpiece W is bent in the second direction F2, thereby forming an eighth bent portion R8.

[0074] As described above, the stabilizer manufacturing method of this embodiment includes the following steps: (1) In the heating step ST1 shown in FIG. 4, the steel workpiece W, which is the material for the stabilizer, is heated to a temperature within the warm-working range. (2) In the forming step (roll bending) ST2 shown in FIG. 4, the heated workpiece W is bent (roll bending) at a temperature suitable for warm forming. This bending (roll bending) is performed by the stabilizer manufacturing apparatus 25, for example, through the steps shown in FIGS. 10 to 16. (3) For example, as shown in FIG. 9, the heated workpiece W is placed on one side (front side) of the forming core metals 61, 161. (4) As shown in FIG. 10, the workpiece W is fixed to the support portions 71, 171 of the forming core metals 61, 161 by one of the pressing members 62, 162. At the same time, the forming core metals 61, 161 are supported by the other pressing member 63, 163. (5) As shown in FIG. 10 , the bending rollers 65, 165 are moved along the arc-shaped forming portions 70, 170, respectively, to bend the workpiece W in the first direction F1. (6) As shown in FIG. 11 , the robot arm 34 moves the workpiece W to the other side (rear side) of the forming core metals 61, 161. (7) As shown in FIG. 12 , the workpiece W is fixed to the support portions 72, 172 of the forming core metals 61, 161 by the pressing members 63, 163. At the same time, the pressing members 62, 162 support the forming core metals 61, 161. (8) The bending rollers 65, 165 are moved along the arc-shaped forming portions 70, 170, respectively, to bend the workpiece W in the second direction F2. Note that in the case of a stabilizer having multiple bending portions at different distances from the eye, the bending portions closest to the eye are bent first, and then the bending portions farthest from the eye are bent. Furthermore, when bending a pair of bent portions at symmetrical positions, a pair of forming mandrels may be used to bend the two bent portions simultaneously. (9) The workpiece W is removed from the forming mandrels 61, 161. (10) In the eye portion forming step ST3 in Figure 4, the eye portions 18, 19 are bent using an eye portion mold so that they form angles θ1, θ2 (shown in Figure 2). (11) The workpiece W is set on an electrode for electrical heating, which is an example of a heating means. (12) In the reheating step ST4 in Figure 4, current is passed through the workpiece W through the electrode. This heats the workpiece W to a temperature suitable for hardening.The workpiece W may be heated in a heating furnace. (13) In the quenching step ST5 in Fig. 4, the heated workpiece W is placed in a coolant and quenched.

[0075] According to the stabilizer manufacturing apparatus and manufacturing method of this embodiment, stabilizers having a plurality of bent portions each having a different radius of curvature can be efficiently manufactured. Moreover, roll bending is performed in the warm region below point A1 using a forming mandrel having an arcuate surface and a bending roller. This avoids problems such as scale and decarburization on the surface of the stabilizer, and prevents the occurrence of so-called scale defects. Moreover, compared to cold forming, deformation resistance is smaller, and bent portions with high shape accuracy can be formed relatively easily.

[0076] The manufacturing apparatus and manufacturing method of the present invention can be used in the field of manufacturing stabilizers of various types, including stabilizers for vehicles.

[0077] 10... stabilizer, 25... stabilizer manufacturing apparatus, 30... base, 31... first forming unit, 32... second forming unit, 33... robot, 34... robot arm, 35... holding portion, 51... first unit drive mechanism, 52... second unit drive mechanism, 60... first movable frame, 61... first forming core bar, 62... first front pressing member, 63... first rear pressing member, 64... first bending roller mechanism, 65... first bending roller, 65a... groove, 66... ​​actuator, 70... first forming portion, 70a... large diameter arc surface, 70b... small diameter arc surface, 70c... minimum arc surface, 71... front support portion, 72... rear support portion, 75... first turning rotation mechanism, 80...first front actuator, 81...first rear actuator, 86...first lifting mechanism, 160...second movable frame, 161...second forming core bar, 162...second front holding member, 163...second rear holding member, 164...second bending roller mechanism, 165...second bending roller, 165a...groove, 166...actuator, 170...second forming portion, 170a...large diameter arc surface, 170b...small diameter arc surface, 170c...minimum arc surface, 171...front support portion, 172...rear support portion, 175...second rotation mechanism, 180...second front actuator, 181...second rear actuator, 186...second lifting mechanism.

Claims

1. A stabilizer manufacturing apparatus comprising a first forming unit (31) and a second forming unit (32), wherein the first forming unit (31) comprises: a first forming core (61) having a first forming portion (70) having an arc shape when viewed from above, a front support portion (71) for supporting a work, and a rear support portion (72) for supporting the work; a first front pressing member (62) for clamping the work between the first forming core (61) and the first forming core (61); a first rear pressing member (63) for clamping the work between the first forming core (61) and the first forming core (61); and a first bending roller (65) that revolves along the first forming portion (70); and the second forming unit (32) comprises: A stabilizer manufacturing apparatus comprising: a second forming core (161) having a second forming portion (170) that is arc-shaped when viewed from above, a front support portion (171) that supports the work, and a rear support portion (172) that supports the work; a second front pressing member (162) that clamps the work between the second forming core (161); a second rear pressing member (163) that clamps the work between the second forming core (161); and a second bending roller (165) that rotates along the second forming portion (170).

2. A stabilizer manufacturing apparatus according to claim 1, wherein the first forming core metal (61) and the second forming core metal (161) are bilaterally symmetrical to each other.

3. A stabilizer manufacturing apparatus according to claim 1, wherein the first forming unit (31) and the second forming unit (32) are movable along guide members (41), (42), (43), and (44) extending horizontally, respectively, and the stabilizer manufacturing apparatus is equipped with a first unit drive mechanism (51) for moving the first forming unit (31) and a second unit drive mechanism (52) for moving the second forming unit (32).

4. A stabilizer manufacturing apparatus according to claim 1, wherein the first forming portion (70) has a large-diameter arcuate surface (70a) with a first radius of curvature (r1) and a small-diameter arcuate surface (70b) with a second radius of curvature (r2) smaller than the first radius of curvature (r1), and the second forming portion (170) has a large-diameter arcuate surface (170a) with the first radius of curvature (r1) and a small-diameter arcuate surface (170b) with the second radius of curvature (r2).

5. A stabilizer manufacturing apparatus according to claim 4, wherein the first forming core metal (61) and the second forming core metal (161) are each movable in the vertical direction, and the stabilizer manufacturing apparatus comprises: a first lifting mechanism (86) that moves the first forming core metal (61) so that the large diameter arc surface (70a) or the small diameter arc surface (70b) of the first forming core metal (61) is at the same height as the first bending roller (65); and a second lifting mechanism (186) that moves the second forming core metal (161) so that the large diameter arc surface (170a) or the small diameter arc surface (170b) of the second forming core metal (161) is at the same height as the second bending roller (165).

6. A stabilizer manufacturing apparatus according to claim 1, comprising: a first front actuator (80) for moving the first front holding member (62) toward the first forming core bar (61); a first rear actuator (81) for moving the first rear holding member (63) toward the first forming core bar (61) in synchronization with the first front holding member (62); a second front actuator (180) for moving the second front holding member (162) toward the second forming core bar (161); and a second rear actuator (181) for moving the second rear holding member (163) toward the second forming core bar (161) in synchronization with the second front holding member (162).

7. A stabilizer manufacturing apparatus according to claim 1, wherein the first bending roller (65) has a groove (65a) on its peripheral surface corresponding to the diameter of the workpiece, and the second bending roller (165) has a groove (165a) on its peripheral surface corresponding to the diameter of the workpiece.

8. A stabilizer manufacturing apparatus according to claim 1, further comprising a robot arm (34) having a holding section (35) for holding and moving the workpiece, wherein the robot arm (34) places the workpiece in front of the first forming core bar (61) and the second forming core bar (161) when bending the workpiece in a first direction, and moves the workpiece to the rear of the first forming core bar (61) and the second forming core bar (161) when bending the workpiece in a second direction.

9. A stabilizer manufacturing apparatus as described in claim 8, wherein the robot arm (34) rotates the workpiece around its axis and sets it in front of or behind the first forming core bar (61) and the second forming core bar (161) depending on the direction in which the workpiece is to be bent.

10. A method for manufacturing a stabilizer, comprising: heating a steel workpiece, which is the material of the stabilizer, to a temperature below point A1 suitable for warm working; setting the heated workpiece on a forming mandrel (61) (161) having a forming portion (70) (170) including a plurality of arcuate surfaces with different radii of curvature; fixing the workpiece to the forming mandrel (61) (161) with pressing members (62) (63) (162) (163); bending the workpiece to a radius of curvature corresponding to the selected arcuate surface by moving a rotatable bending roller (65) (165) along a selected arcuate surface of the forming portion (70) (170); reheating the workpiece to a temperature at which hardening is possible; and quenching the reheated workpiece by placing it in a coolant to cool it.

11. A method for manufacturing a stabilizer as claimed in claim 10, wherein when the workpiece is set on the forming core metal (61) (161), the workpiece is rotated around its axis by a robot arm (34) in accordance with the direction in which the workpiece is to be bent.

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