Plastic deformation apparatus and plastic deformation method

Abstract

In a plastic deformation apparatus and method for reducing the diameter of a rod-shaped workpiece, the aim is to improve processing accuracy and yield. [Solution] The device includes a holding and moving unit 11 that holds the workpiece 2 such that the angle between the workpiece central axis 2a, which is the central axis of the rod-shaped workpiece 2, and the horizontal plane is 45° or more, and moves the workpiece 2 in the direction of the workpiece central axis 2a; a plurality of molding rollers 121 that rotate around the molding roller rotation shaft 121a and press against the workpiece 2 so that their outer surfaces sandwich the workpiece 2, thereby reducing the diameter of the workpiece 2, and are arranged such that the angle between the molding roller rotation shaft 121a and the workpiece central axis 2a is 45° or less; and a leveling roller 131 that leveles the surface of the workpiece 2 formed by the molding rollers 121.

Description

Technical Field

[0001] The present invention relates to a plastic processing apparatus and a plastic processing method.

Background Art

[0002] Conventionally, as a method for forming metal products, a forming method by die forging has been widely used. As an example of the forming method by die forging, first, rough forging is performed using a rough forging die to forge and form an intermediate forging product, and then, finish forging is performed on the intermediate forging product using a finish forging die to form a final forging product. This forming method is widely used.

[0003] In such a forming method that performs rough forging and finish forging, a rough forging die and a finish forging die are required, and the die cost becomes high. In particular, when forming forged products with multiple product types and small quantities, the ratio of the die in the cost of one forged product becomes high, so the product cost inevitably becomes high.

[0004] Therefore, conventionally, Patent Document 1 describes a forming method in which, instead of rough forging, the intermediate portion of a bar-shaped workpiece (hereinafter referred to as a work) is processed to have a smaller diameter to obtain an intermediate forging product. In this prior art, since it is possible to form intermediate forging products of multiple product types with a general-purpose forging apparatus, the product cost can be reduced compared to the case of preparing a dedicated rough forging die for each product type.

[0005] A general-purpose forging apparatus for forming an intermediate forging product in Patent Document 1 presses a bar-shaped work downward toward the axial center with a forming roll to reduce its diameter. Specifically, this forging apparatus holds a bar-shaped work in a horizontally lying posture and holds one end and the other end with the gripping portions of a manipulator so as to be rotatable.

[0006] A hydraulic cylinder rod is connected to the gripping section that holds one end of the workpiece. The hydraulic cylinder acts as an absorption mechanism that absorbs the axial elongation of the workpiece during machining. When the workpiece elongates, the cylinder rod retracts in accordance with the elongation, meaning the hydraulic cylinder contracts and absorbs the elongation of the workpiece. Any bulges that occur on the outer part of the workpiece in the width direction of the forming roll are pressed and smoothed by the leveling roller. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6291938 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the conventional technology described above, the rod-shaped workpiece is processed to reduce its diameter while lying horizontally. As a result, the rod-shaped workpiece is susceptible to gravity during the reduction process and tends to sag downwards in the direction of gravity due to its own weight.

[0009] In the conventional technology described above, the end of the rod-shaped workpiece is gripped, which leaves gripping marks on the intermediate forged product. If these marks remain on the final forged product, it can result in a quality defect. Therefore, in order to obtain a final forged product without quality defects, it becomes necessary to remove the gripping marks at either the intermediate or final forged product stage by means of cutting, machining, or other methods, which reduces the yield.

[0010] This invention was made in view of the above background, and aims to improve processing accuracy and yield in a plastic deformation apparatus and method for reducing the diameter of a rod-shaped workpiece. [Means for solving the problem]

[0011] A first aspect of the present invention is: A holding and moving unit that holds the workpiece such that the angle between the central axis of the rod-shaped workpiece and the horizontal plane is 45° or more, and moves the workpiece in the direction of the central axis of the workpiece, A plurality of molding rollers are arranged such that the angle between the molding roller rotation axis and the central axis of the workpiece is 45° or less, and the outer surfaces of the molding rollers press against the workpiece while rotating, thereby reducing the diameter of the workpiece, and the angle between the molding roller rotation axis and the central axis of the workpiece is 45° or less. The plastic deformation apparatus includes a leveling roller for leveling the surface of the workpiece formed by the molding roller.

[0012] A second aspect of the present invention is: A workpiece holding step in which the workpiece is held such that the angle between the central axis of the rod-shaped workpiece and the horizontal plane is 45° or more, The plastic deformation method includes a plastic deformation step of arranging a plurality of molding rollers that rotate around a molding roller rotation axis such that the angle between the molding roller rotation axis and the workpiece central axis is 45° or less, reducing the diameter of the workpiece by pressing the outer surfaces of the plurality of molding rollers against the workpiece while moving the workpiece in the direction of the workpiece central axis, and smoothing the surface of the workpiece formed by the molding rollers with a smoothing roller. [Effects of the Invention]

[0013] According to the first aspect of the present invention, since the rod-shaped workpiece is processed to reduce its diameter in a position closer to an upright position in the direction of gravity than in a horizontally laid position, it is possible to suppress the rod-shaped workpiece from sagging downward in the direction of gravity due to its own weight during the diameter reduction process. Furthermore, since it is easier to hold the rod-shaped workpiece compared to when it is processed to reduce its diameter in a horizontally laid position, it is possible to suppress the occurrence of marks left by holding the workpiece that result in quality defects.

[0014] According to the second aspect of the present invention, similar to the first aspect of the present invention, it is possible to suppress the bar-shaped workpiece from being affected by gravity and sagging downward in the direction of gravity due to its own weight during the diameter reduction process, and it is possible to suppress the marks left by holding the workpiece from becoming quality defects.

[0015] Therefore, according to the first and second aspects of the present invention, in a plastic processing apparatus and a plastic processing method for performing diameter reduction processing on a bar-shaped workpiece, it is possible to improve the processing accuracy and yield.

Brief Description of the Drawings

[0016] [Figure 1] Front view showing the plastic processing apparatus in Embodiment 1. [Figure 2] Side view showing the plastic processing apparatus in Embodiment 〖1〗. [Figure 3] Perspective view schematically showing the arrangement relationship between the forming roller and the flattening roller in Embodiment 1. [Figure 4] Flowchart showing the plastic processing method in Embodiment 1. [Figure 5] Schematic diagram for explaining the operation of the plastic processing apparatus during radial forming in Embodiment 1. [Figure 6] Schematic diagram for explaining the operation of the plastic processing apparatus during thrust forming in Embodiment 1. [Figure 7] External view showing the workpiece after radial forming in Embodiment 1. [Figure 8] External view showing the workpiece after thrust forming in Embodiment 1. [Figure 9] External view showing the workpiece in which radial forming and thrust forming are combined in Embodiment 1. [Figure 10] Explanatory drawing showing an example of the shape of the workpiece that can be formed by the plastic processing apparatus of Embodiment 1. [Figure 11] Cross-sectional view showing the plastic processing apparatus in Embodiment 2, which is the cross-sectional view taken along the line XI-XI in FIG. 12. [Figure 12] Cross-sectional view taken along the line XII-XII in FIG. 11. [Figure 13]A cross-sectional view showing the processing process by the plastic deformation apparatus in Embodiment 2. [Figure 14] A cross-sectional view showing the completion of processing by the plastic deformation apparatus in Embodiment 2. [Figure 15] A cross-sectional view showing a plastic deformation apparatus in Embodiment 3, specifically the XV-XV cross-sectional view in Figure 16. [Figure 16] Figure 15 shows the cross-sectional view between XVI and XVI. [Figure 17] A cross-sectional view showing the completion of processing by the plastic deformation apparatus in Embodiment 3. [Figure 18] A cross-sectional view showing a plastic deformation apparatus in Embodiment 4. [Figure 19] A cross-sectional view showing the processing process by the plastic deformation apparatus in Embodiment 4. [Figure 20] A cross-sectional view showing the completion of processing by the plastic deformation apparatus in Embodiment 4. [Modes for carrying out the invention]

[0017] The plastic deformation apparatus comprises a holding and moving unit that holds the workpiece such that the angle between the workpiece central axis, which is the central axis of the rod-shaped workpiece, and the horizontal plane is 45° or more, and moves the workpiece in the direction of the workpiece central axis; a plurality of forming rollers that rotate around a forming roller rotation axis and press against the workpiece so that their outer surfaces clamp the workpiece, thereby reducing the diameter of the workpiece, and are arranged such that the angle between the forming roller rotation axis and the workpiece central axis is 45° or less; and a leveling roller that levels the surface of the workpiece formed by the forming rollers.

[0018] In a plastic deformation apparatus, the holding and moving part may have a receiving part that receives the lower end surface of the workpiece from below in the direction of gravity. Compared to the conventional technique described above, where a rod-shaped workpiece is laid horizontally and its end is gripped, the holding of the rod-shaped workpiece is easier, and thus the marks left by the workpiece during handling can be effectively suppressed as defects in quality.

[0019] The molding roller is configured to restrict the length from the center of the workpiece's diameter reduction position, which corresponds to the widthwise center position of the molding roller, to the lower end surface of the workpiece, and to allow the length from the center of the workpiece's diameter reduction position to the upper end surface of the workpiece to extend. The leveling roller is positioned within a range including the widthwise center position of the molding roller, has a lower length from the widthwise center position of the molding roller to the lower end of the leveling roller, and has an upper length from the widthwise center position of the molding roller to the upper end of the leveling roller, the lower length may be longer than the upper length.

[0020] Therefore, when the diameter of the workpiece is reduced, the portion of the workpiece below the center position in the width direction of the forming roller does not elongate and is always leveled and formed by the leveling roller. On the other hand, as the diameter of the workpiece is reduced, the workpiece elongates upward. If the workpiece elongates upward by an amount exceeding the upper length of the leveling roller, it may not be leveled and formed by the leveling roller.

[0021] However, as the workpiece expands upward, at a certain point, radial expansion stops in the upper part of the workpiece's tapered section, and only upward expansion occurs. If the leveling roller remains in contact with the workpiece when it separates from the forming roller and expands upward, the leveling roller will exert a force that resists the workpiece's upward expansion. As a result, burrs may form on the workpiece. However, as described above, by making the upper length of the leveling roller shorter than the lower length, the formation of burrs on the workpiece can be suppressed.

[0022] The upper corner portion of the workpiece's tapered portion, located closer to the upper end surface, transitions from contact with the forming roller to a separated state as the length from the center of the tapered portion of the workpiece to the upper end surface of the workpiece increases with the tapering of the workpiece. The upper end of the leveling roller is positioned to correspond to the position of the upper corner portion of the workpiece at the time of separation from the forming roller. This suppresses the formation of burrs on the workpiece, as described above.

[0023] The upper length should be set to a different length depending on the outer diameter of the workpiece. The separation timing described above differs depending on the outer diameter of the workpiece. Therefore, by setting the upper length to an appropriate length according to the outer diameter of the workpiece, burrs can be prevented from forming on the workpiece.

[0024] The rotation axis of the leveling roller is positioned parallel to the central axis of the workpiece, and the leveling roller is preferably supported by both sides. This reduces the amount of deflection of the leveling roller, allowing the workpiece to be formed into the desired shape. The outer surface of the leveling roller may have a cylindrical surface. In this case, it becomes easier to support the leveling roller by both sides.

[0025] The rotation axis of the leveling roller is inclined with respect to the central axis of the workpiece, and the leveling roller may be cantilevered. This allows for increased rigidity of the support portion of the leveling roller, even if the leveling roller has a small diameter. By making the leveling roller smaller, the molding roller can be made larger, thereby increasing molding efficiency. Furthermore, by increasing the support rigidity of the leveling roller, the accuracy of leveling molding can be improved. In this case, the outer circumferential surface of the leveling roller may have a conical surface.

[0026] The leveling roller may be cantilevered at a portion near the base end of the conical surface, with the base end of the conical surface positioned closer to the lower end surface of the workpiece than the widthwise center position of the forming roller, the tip of the conical surface forming a free end, with the tip of the conical surface positioned closer to the upper end surface of the workpiece than the widthwise center position of the forming roller.

[0027] In a leveling roller, the area below the center in the width direction of the molding roller experiences a greater load than the area above it. Therefore, by positioning the area near the base of the conical surface of the leveling roller lower, the outer diameter of the lower area, which experiences a greater load, can be increased. This improves the accuracy of leveling molding.

[0028] The leveling roller may be configured to restrict the length from the center position of the workpiece's diameter reduction, which corresponds to the widthwise center position of the forming roller, to the lower end face of the workpiece in the axial direction, and to allow the length from the center position of the workpiece's diameter reduction to the upper end face of the workpiece in the axial direction, and to allow the leveling roller to include a lower leveling roller whose downward movement is restricted relative to the forming roller and which leveles the lower expansion portion located closer to the lower end face of the workpiece than the center position of the workpiece's diameter reduction when the workpiece is reduced in diameter, and an upper leveling roller which is arranged to move upward relative to the forming roller and which leveles the upper expansion portion located closer to the upper end face of the workpiece than the center position of the workpiece's diameter reduction when the workpiece is reduced in diameter, and which moves upward relative to the lower leveling roller as the upper expansion portion moves in the axial direction.

[0029] As the upper expansion section moves upward, the upper leveling roller moves upward in conjunction with the upward movement of the upper expansion section. Therefore, the formation of burrs on the workpiece can be suppressed as the upper expansion section is leveled and formed.

[0030] The lower leveling roller may be rotatably supported on a support shaft and restricted from moving downward relative to the support shaft, while the upper leveling roller may be rotatably supported on the support shaft and provided to be movable upward along the support shaft.

[0031] In a plastic deformation apparatus, the holding and moving part may have a drive mechanism that moves the workpiece in the direction of the workpiece's central axis by driving the receiving part in the direction of the workpiece's central axis. A mechanism that holds a rod-shaped workpiece and moves it in the direction of the workpiece's central axis can be realized with a simple configuration.

[0032] In a plastic deformation apparatus, the receiving portion may be capable of driven rotation around the central axis of the workpiece. Since the workpiece, which rotates driven by the forming roller, can be securely held by the receiving portion, the processing accuracy can be further improved.

[0033] In a plastic deformation apparatus, the holding and moving part has a cylindrical portion into which the workpiece is inserted, and the receiving part may move relative to the cylindrical portion in the direction of the workpiece's central axis. Since the workpiece can be securely held by the receiving part and the cylindrical portion as it moves in the direction of the workpiece's central axis, the processing accuracy can be further improved.

[0034] In a plastic deformation apparatus, the receiving portion may be movable to a position that protrudes above the upper end of the cylindrical portion in the direction of gravity. This makes it possible to reduce the diameter of the rod-shaped workpiece all the way to the lower end using the forming rollers, thereby further improving the yield.

[0035] In a plastic deformation apparatus, the receiving portion may be capable of driven rotation around the central axis of the workpiece. In a configuration in which the workpiece is held by the receiving portion and the cylindrical portion, the workpiece, which rotates driven by the forming roller, can be securely held by the receiving portion, thereby further improving the processing accuracy.

[0036] In a plastic deformation apparatus, the holding and moving part may have a cylindrical portion into which the workpiece is inserted. Since the workpiece can be held by the cylindrical portion, the processing accuracy can be further improved.

[0037] In a plastic deformation apparatus, the cylindrical portion may be capable of driven rotation around the central axis of the workpiece. Since the workpiece, which rotates driven by the forming roller, can be held by the cylindrical portion, the processing accuracy can be further improved.

[0038] A plastic deformation apparatus may be provided with a centering unit that suppresses the axial runout of the workpiece by regulating the radial position of the upper end of the workpiece. By suppressing the axial runout of the workpiece at the upper end, machining accuracy can be further improved.

[0039] In a plastic deformation apparatus, the centering unit may suppress the axial runout of the workpiece by pressing the upper end surface of the workpiece downward in the direction of gravity. This suppresses the axial runout of the workpiece while preventing the formation of marks on the upper end of the workpiece where the workpiece was held, thereby further improving processing accuracy and yield.

[0040] In a plastic deformation apparatus, the centering unit may be capable of driven rotation around the central axis of the workpiece. Since the centering unit can reliably suppress the axial runout of the workpiece that rotates driven by the forming rollers, the processing accuracy can be further improved.

[0041] In a plastic deformation apparatus, the centering unit may be capable of moving in the direction of the workpiece's central axis. Since the centering unit can reliably suppress the runout of the workpiece when the workpiece is being moved in the direction of the workpiece's central axis by the holding and moving unit, the machining accuracy can be further improved.

[0042] The plastic deformation method includes a workpiece holding step of holding the workpiece such that the angle between the workpiece central axis, which is the central axis of the rod-shaped workpiece, and the horizontal plane is 45° or more, and a plastic deformation step of arranging a plurality of forming rollers that rotate around a forming roller rotation axis such that the angle between the forming roller rotation axis and the workpiece central axis is 45° or less, and reducing the diameter of the workpiece by pressing the outer surfaces of the plurality of forming rollers together so as to sandwich the workpiece while moving the workpiece in the direction of the workpiece central axis, and then smoothing the surface of the workpiece formed by the forming rollers with a smoothing roller.

[0043] (Embodiment 1) 1. Overall configuration of the plastic deformation machine The plastic deformation apparatus 1 shown in Figures 1 and 2 is a general-purpose plastic deformation apparatus capable of forming various types of rough materials. A rough material is a preformed product created in the stage before finish forging. The plastic deformation apparatus 1 forms the rough material by plastic deformation of a rod-shaped (cylindrical in this example) workpiece 2. The rough material formed from the workpiece 2 by the plastic deformation apparatus 1 is then formed into, for example, a steering attachment, which is an automobile part, by finish forging. The workpiece 2 can be either a cold-worked material or a hot-worked material.

[0044] Plastic deformation apparatus 1 is capable of plastically deformation of workpiece 2 by using a combination of radial forming and thrust forming. Radial forming is a method of forming workpiece 2 by applying a radial load (a load perpendicular to the axis of workpiece 2). Thrust forming is a method of forming workpiece 2 by applying a thrust load (a load parallel to the axis of workpiece 2).

[0045] In Figures 1 and 2, the X, Y, and Z directions represent the directions in a Cartesian coordinate system, with the X and Y directions being parallel to the horizontal and the Z direction being parallel to gravity.

[0046] The plastic deformation apparatus 1 comprises a holding and moving section 11, a pair of forming roller units 12, a pair of leveling roller units 13, a centering section 14, and a control device 15.

[0047] The holding and moving part 11 holds the lower end of the workpiece 2 and moves the workpiece 2 in the direction of the workpiece central axis 2a, which is the central axis of the workpiece 2. The holding and moving part 11 is a thrust unit having a cylindrical part 111, a receiving part 112, and a drive mechanism 113.

[0048] The cylindrical portion 111 is a member that holds the orientation of the workpiece 2 that has been brought into the plastic deformation apparatus 1. The cylindrical portion 111 is a cylindrical member having an inner diameter slightly larger than the outer diameter of the workpiece 2. The cylindrical portion 111 is positioned such that the direction in which the central axis of the cylindrical portion 111a extends is closer to the direction of gravity than to the horizontal direction. That is, the cylindrical portion 111 is positioned such that the angle between the central axis of the cylindrical portion 111a and the direction of gravity is 45° or less. In this example, the cylindrical portion 111 is positioned such that the central axis of the cylindrical portion 111a is parallel to the direction of gravity. That is, in this example, the cylindrical portion 111 is positioned such that the angle between the central axis of the cylindrical portion 111a and the direction of gravity is 0°.

[0049] The cylindrical portion 111 is supported in the holding and moving portion 11 so as to be able to rotate coaxially with the central axis 111a of the cylindrical portion by external force. Specifically, the cylindrical portion 111 is able to rotate in accordance with the rotation of the workpiece 2.

[0050] The receiving portion 112 is a thrust member that receives the lower end surface 21 of the workpiece 2 from below in the direction of gravity and moves the workpiece 2 in the direction of gravity by being displaced in the direction of gravity. In other words, the receiving portion 112 supports the lower end surface 21 of the workpiece 2. The receiving portion 112 is a columnar member having an outer diameter smaller than the inner diameter of the cylindrical portion 111 and is arranged coaxially with the cylindrical portion 111.

[0051] The receiving portion 112 is displaceable in the direction of gravity within the cylindrical portion 111. The receiving portion 112 is displaceable up to a point above the upper end of the cylindrical portion 111 in the direction of gravity.

[0052] The receiving portion 112 is supported in the holding and moving portion 11 so as to be able to rotate coaxially with the central axis 111a of the cylindrical portion by external force. Specifically, the receiving portion 112 is able to rotate in accordance with the rotation of the workpiece 2.

[0053] The drive mechanism 113 is an actuator for the receiving part that drives the receiving part 112 linearly in the direction of gravity.

[0054] By inserting the workpiece 2 into the cylindrical portion 111 from above in the direction of gravity and placing it on the upper end surface of the receiving portion 112, the workpiece 2 can be held so that its central axis, the workpiece central axis 2a, is coaxial (parallel) with the cylindrical portion central axis 111a. In other words, the orientation of the workpiece 2 can be held vertically.

[0055] In this example, since the central axis 111a of the cylindrical part is parallel to the direction of gravity, the workpiece 2 can be held so that the central axis 2a of the workpiece is parallel to the direction of gravity.

[0056] Each of the pair of molding roller units 12 includes a molding roller 121, a molding roller motor 122, and a molding roller actuator 123.

[0057] The molding roller 121 rotates around the molding roller rotation axis 121a and presses against the outer surface of the workpiece 2, thereby plastically deforming the workpiece 2 and reducing its diameter.

[0058] The molding roller 121 is positioned such that its rotation axis 121a is closer to parallel than perpendicular to the workpiece central axis 2a. In other words, the molding roller 121 is positioned such that its rotation axis 121a is closer to parallel than perpendicular to the cylindrical central axis 111a.

[0059] In other words, the molding roller 121 is positioned such that the angle between the molding roller rotation axis 121a and the central axis 111a of the cylindrical part is 45° or less.

[0060] In this example, the molding roller 121 is positioned such that its rotation axis 121a is parallel to the central axis 111a of the cylindrical part. That is, in this example, the molding roller 121 is positioned such that the angle between the rotation axis 121a and the central axis 111a of the cylindrical part is 0°.

[0061] The two molding rollers 121 are positioned opposite each other so as to sandwich the workpiece 2. This allows the molding rollers 121 to press against the outer surface of the workpiece 2 in order to reduce its diameter.

[0062] The molding roller motor 122 is a rotary drive unit for the molding roller that rotates the molding roller 121. The molding roller actuator 123 linearly displaces the molding roller 121 so as to move it closer to or further away from the workpiece 2. In this example, the molding roller actuator 123 linearly displaces the molding roller 121 in a direction perpendicular to the molding roller rotation axis 121a.

[0063] Each leveling roller unit 13 comprises a leveling roller 131 and a leveling roller actuator 132.

[0064] The leveling roller 131 presses against the outer surface of the workpiece 2, leveling and shaping it. In other words, the leveling roller 131 suppresses the formation of bulging portions (so-called excess material) on both outer widthwise sides of the forming roller 121 when the workpiece 2 is reduced in diameter by the forming roller 121. These bulging portions may occur near one axial end of the workpiece 2 and near the other axial end of the workpiece 2.

[0065] The leveling roller 131 rotates around the leveling roller rotation axis 131a. The leveling roller 131 is positioned such that the leveling roller rotation axis 131a is parallel to the workpiece central axis 2a. In other words, the leveling roller 131 is positioned such that the leveling roller rotation axis 131a is parallel to the cylindrical central axis 111a. That is, the leveling roller 131 is positioned such that the angle between the leveling roller rotation axis 131a and the cylindrical central axis 111a is 0°.

[0066] The two leveling rollers 131 are positioned opposite each other so as to sandwich the workpiece 2.

[0067] The leveling roller 131 is supported in the leveling roller unit 13 so as to be rotatable by external force. Specifically, the leveling roller 131 is rotatable in accordance with the rotation of the workpiece 2.

[0068] The leveling roller actuator 132 linearly displaces the leveling roller 131 so as to move it closer to or further away from the workpiece 2. In this example, the leveling roller actuator 132 linearly displaces the leveling roller 131 in a direction perpendicular to the leveling roller rotation axis 131a.

[0069] The positions of the two leveling rollers 131 in the direction of the workpiece central axis 2a (Z direction, gravity direction) overlap with the positions of the two forming rollers 121.

[0070] The centering unit 14 is a centering unit having a centering member 141 and a cylinder 142, and suppresses axial runout of the workpiece 2 by regulating the radial position of the upper end of the workpiece 2. The centering member 141 is a member for pressing the upper end surface 22 of the workpiece 2 downward in the direction of gravity, and contacts the upper end surface 22 of the workpiece 2. That is, by sandwiching the workpiece 2 between the centering member 141 and the receiving part 112 in the direction of the workpiece central axis 2a, the radial position of the upper end of the workpiece 2 during plastic deformation is regulated, thereby centering the workpiece 2. This suppresses runout of the workpiece central axis 2a during plastic deformation.

[0071] The centering member 141 is supported in the centering section 14 so as to be rotatable by external force. Specifically, the centering member 141 is rotatable in accordance with the rotation of the workpiece 2.

[0072] The cylinder 142 applies a biasing force to the self-aligning member 141 in the direction of gravity, downward. In this example, the cylinder 142 is an air cylinder, and it is capable of biasing the workpiece 2 downward in the direction of gravity via the self-aligning member 141 while also following the upward displacement of the workpiece 2 in the direction of gravity caused by the receiving portion 112.

[0073] The control device 15 controls the operation of the drive mechanism 113, the molding roller motor 122, the molding roller actuator 123, the leveling roller actuator 132, and the cylinder 142.

[0074] Figure 3 is a schematic perspective view showing the arrangement of the forming rollers 121 and leveling rollers 131 with respect to the workpiece 2. The positions of the two leveling rollers 131 in the circumferential direction of the workpiece 2 are different from those of the two forming rollers 121 so that the two leveling rollers 131 do not interfere with the two forming rollers 121. In this example, the positions of the two leveling rollers 131 in the circumferential direction of the workpiece 2 are 90° different from those of the two forming rollers 121.

[0075] The width dimension (Z-direction dimension) of the leveling roller 131 is greater than the width dimension (Z-direction dimension) of the forming roller 121. The two leveling rollers 131 are positioned such that, in the direction of the workpiece central axis 2a (Z-direction), both ends of the leveling roller 131 in the width direction (Z-direction) are located further out than both ends of the forming roller 121 in the width direction (Z-direction).

[0076] 2. Plastic deformation method using a plastic deformation apparatus The plastic deformation method of workpiece 2 using plastic deformation apparatus 1 will be described. As shown in Figure 4, the plastic deformation method of workpiece 2 using plastic deformation apparatus 1 includes a workpiece holding step S100, a plastic deformation step S110, and a workpiece unloading step S120.

[0077] In the workpiece holding process S100, the workpiece 2 is inserted into the cylindrical portion 111 from above in the direction of gravity and placed on the upper end surface of the receiving portion 112. This holds the workpiece 2 so that its central axis 2a is parallel to the central axis 111a of the cylindrical portion. In other words, the orientation of the workpiece 2 is held vertically. The workpiece holding process S100 is a workpiece loading process in which the workpiece 2 is loaded into the plastic deformation apparatus 1.

[0078] In the plastic deformation process S110, the control device 15 performs thrust control, centering control, forming roller control, and leveling roller control to perform the desired diameter reduction process on the workpiece 2.

[0079] In thrust control, the drive mechanism 113 drives the receiving portion 112 in the direction of gravity, thereby displacing the workpiece 2 placed on the receiving portion 112 to a predetermined position in the direction of gravity.

[0080] In thrust control, the original position of the support portion 112 is set such that the upper end of the support portion 112 is located below the upper end of the cylindrical portion 111 in the direction of gravity. Therefore, when the support portion 112 is in its original position or below its original position in the direction of gravity, and the workpiece 2 is inside the cylindrical portion 111, the outer circumferential surface of the workpiece 2 is supported by the inner circumferential surface of the cylindrical portion 111, so that the workpiece 2 is stably held in a vertical position.

[0081] In the self-aligning control, the cylinder 142 drives the self-aligning member 141 downward in the direction of gravity, thereby pressing the upper end of the workpiece 2 downward in the direction of gravity with the self-aligning member 141. The initial position of the self-aligning member 141 in the self-aligning control is set at a position spaced away from the upper end of the workpiece 2.

[0082] In the molding roller control, the molding roller 121 is rotated by the molding roller motor 122, while the molding roller actuator 123 moves the molding roller 121 closer to and further away from the workpiece 2.

[0083] The outer surface of the workpiece 2 is pressed by the forming roller 121, causing the workpiece 2 to become smaller in diameter. When the outer surface of the workpiece 2 is pressed by the forming roller 121, the workpiece 2 rotates in accordance with the forming roller 121. As the workpiece 2 rotates in accordance with the forming roller 121, the receiving portion 112, the centering member 141, and the leveling roller 131 rotate in accordance with the workpiece 2.

[0084] When the outer surface of the workpiece 2 is pressed by the forming roller 121, the workpiece 2 is sandwiched between the two forming rollers 121. Therefore, even if the lower end of the workpiece 2 is displaced above the upper end of the cylindrical portion 111 in the direction of gravity, the workpiece 2 can still be held by the two forming rollers 121, allowing the workpiece 2 to be reduced in diameter along its entire longitudinal direction, from its upper end to its lower end.

[0085] In the molding roller control, the initial position of the molding roller 121 is set to a position spaced apart from the outer surface of the workpiece 2.

[0086] In the leveling roller control, the leveling roller actuator 132 brings the leveling roller 131 into contact with the outer circumferential surface of the workpiece 2. The leveling roller 131 suppresses the excess material of the workpiece 2 that is generated on both outer widthwise portions of the forming roller 121.

[0087] In the leveling roller control, the initial position of the leveling roller 131 is set at a position spaced away from the outer surface of the workpiece 2.

[0088] By using thrust control, the longitudinal position of the workpiece 2 relative to the molding roller 121 is adjusted, so that a desired portion of the workpiece 2 in the longitudinal direction can be made smaller in diameter.

[0089] By controlling the molding rollers, the position of the molding rollers 121 in the radial direction of the workpiece 2 is adjusted, so that the workpiece 2 can be reduced in diameter to a desired outer diameter.

[0090] By arbitrarily combining thrust control and forming roller control, at least one or both of radial forming and thrust forming can be applied to the workpiece 2.

[0091] Figure 5 is a schematic diagram showing the operation of the plastic deformation apparatus 1 during radial forming. Figure 6 is a schematic diagram showing the operation of the plastic deformation apparatus 1 during thrust forming. During radial forming, a radial load (a load perpendicular to the central axis 2a of the workpiece) is applied to the workpiece 2 to form it. During thrust forming, a thrust load (a load parallel to the central axis 2a of the workpiece) is applied to the workpiece 2 to form it.

[0092] Figure 7 shows a workpiece 2 that has undergone radial forming. When radial forming is performed on workpiece 2, the longitudinal position of workpiece 2 relative to the forming roller 121 is adjusted by thrust control, and then the longitudinal displacement of workpiece 2 is stopped. Then, the position of the forming roller 121 in the radial direction of workpiece 2 is displaced to a predetermined position by forming roller control, thereby reducing the diameter of workpiece 2. In the example in Figure 7, multiple parts of workpiece 2 are reduced in diameter by performing such radial forming multiple times.

[0093] Figure 8 shows a workpiece 2 that has undergone thrust forming. When thrust forming is applied to workpiece 2, the longitudinal position of workpiece 2 relative to the forming roller 121 is changed by thrust control, and the position of the forming roller 121 in the radial direction of workpiece 2 is displaced to a predetermined position by forming roller control, thereby reducing the diameter of workpiece 2. In the example in Figure 8, the upper end of workpiece 2 is reduced in diameter by applying such thrust forming to the upper end of workpiece 2.

[0094] Figure 9 shows a workpiece 2 that has been subjected to a combination of radial and thrust forming. When radial and thrust forming are used in combination on workpiece 2, the longitudinal position of workpiece 2 relative to the forming roller 121 is changed by thrust control, while the forming roller control continuously displaces the forming roller 121 in the radial direction of workpiece 2, thereby reducing the diameter of workpiece 2. In other words, the forming roller 121 moves relative to workpiece 2 like a human hand in pottery making on a potter's wheel, resulting in the formation of workpiece 2 with various outer diameters.

[0095] When radial forming and thrust forming are used in combination for workpiece 2, the displacement direction of workpiece 2 due to thrust control is basically unidirectional, and workpiece 2 is basically displaced from the downward side in the direction of gravity to the upward side in the direction of gravity.

[0096] When radial forming and thrust forming are used in combination for workpiece 2, the displacement direction of workpiece 2 by thrust control may be bidirectional depending on the shape to be formed. In other words, workpiece 2 may be displaced reciprocally in the longitudinal direction.

[0097] In the plastic deformation process S110, once the desired diameter reduction of the workpiece 2 is completed, the receiving portion 112, the centering member 141, the forming roller 121, and the leveling roller 131 are all returned to their original positions, and the rotation of the forming roller 121 is stopped. As a result, the workpiece 2 after the diameter reduction is completed is held inside the cylindrical portion 111.

[0098] In the workpiece removal process S120, the workpiece 2, which has undergone diameter reduction processing, is removed from the cylindrical section 111 and then transported to the next process.

[0099] 3. Effects Figure 10 shows an example of the shape of the workpiece 2 that can be formed by the plastic deformation apparatus 1 of this embodiment. By combining radial forming and thrust forming in various ways on the workpiece 2, various diameter reduction processes can be applied to the workpiece 2 to form rough shapes of various types. The various workpieces 2 formed by the plastic deformation apparatus 1 are then formed into various final forged products by corresponding finish forging processes.

[0100] As described above, the plastic deformation apparatus 1 and plastic deformation method of this embodiment allow for various diameter reduction processes on the workpiece 2 by combining thrust control, centering control, forming roller control, and leveling roller control in the plastic deformation process S110. Therefore, multiple types of rough materials can be formed in a single process using the same plastic deformation apparatus 1. Consequently, compared to forming multiple types of rough materials using a dedicated forging die for each type, forming costs can be significantly reduced and productivity can be significantly improved.

[0101] In this embodiment, the holding and moving unit 11 holds the workpiece 2 such that the angle between the workpiece central axis 2a and the horizontal plane is 45° or more, and moves the workpiece 2 in the direction of the workpiece central axis 2a. The multiple molding rollers 121 are arranged such that the angle between the molding roller rotation axis 121a and the workpiece central axis 2a is 45° or less.

[0102] According to this method, the rod-shaped workpiece 2 is processed to reduce its diameter in a position closer to an upright position in the direction of gravity than in a horizontal position. This suppresses the downward sagging of the rod-shaped workpiece 2 due to its own weight during the diameter reduction process. Furthermore, compared to processing the rod-shaped workpiece 2 in a horizontal position, it is easier to hold the workpiece 2, thus suppressing quality defects caused by marks left by holding the workpiece 2. Therefore, processing accuracy and yield can be improved.

[0103] In this embodiment, the receiving portion 112 of the holding and moving portion 11 receives the lower end surface of the workpiece 2 from below in the direction of gravity. This makes it easier to hold the rod-shaped workpiece 2 compared to the case where the rod-shaped workpiece 2 is laid horizontally and its end is gripped, thus effectively suppressing the occurrence of defects in quality due to marks left by holding the workpiece 2.

[0104] In this embodiment, the drive mechanism 113 of the holding and moving part 11 moves the workpiece 2 in the direction of the workpiece central axis 2a by driving the receiving part 112 in the direction of the workpiece central axis 2a. This makes it possible to realize a mechanism that holds the rod-shaped workpiece 2 and moves it in the direction of the workpiece central axis 2a with a simple configuration.

[0105] In this embodiment, the receiving portion 112 is rotatable by the workpiece central axis 2a. This allows the workpiece 2, which rotates in accordance with the rotation of the molding roller 121, to be securely held by the receiving portion 112, thereby further improving machining accuracy.

[0106] In this embodiment, the workpiece 2 is inserted into the cylindrical portion 111 of the holding and moving portion 11. This allows the workpiece 2 to be securely held by the receiving portion 112 and the cylindrical portion 111, thereby further improving machining accuracy. Furthermore, the workpiece 2, which is moved in the direction of the workpiece central axis 2a by the receiving portion 112, is securely held by the cylindrical portion 111, thereby further improving machining accuracy.

[0107] In this embodiment, the receiving portion 112 is movable to a position that protrudes above the upper end of the cylindrical portion 111 in the direction of gravity. This allows the molding roller 121 to reduce the diameter of the rod-shaped workpiece 2 all the way to the lower end, thereby further improving the yield.

[0108] In this embodiment, the cylindrical portion 111 is rotatable by following the rotation of the workpiece central axis 2a. This allows the workpiece 2, which rotates in accordance with the rotation of the molding roller 121, to be securely held by the cylindrical portion 111, thereby further improving machining accuracy.

[0109] In this embodiment, a centering unit may be provided to suppress the axial runout of the workpiece by regulating the radial position of the upper end of the workpiece. By suppressing the axial runout of the workpiece at the upper end, machining accuracy can be further improved.

[0110] In this embodiment, the centering unit 14 suppresses the axial runout of the workpiece 2 by pressing the upper end surface of the workpiece 2 downward in the direction of gravity. This suppresses the axial runout of the workpiece 2 while preventing the formation of marks on the upper end of the workpiece 2 where the workpiece 2 was held, thereby further improving machining accuracy and yield.

[0111] In this embodiment, the centering unit 14 is capable of driven rotation around the workpiece central axis 2a. This ensures that the axial runout of the workpiece 2 is reliably suppressed by the centering unit 14 when the forming roller 121 presses the workpiece 2 against it while rotating, thereby further improving machining accuracy.

[0112] In this embodiment, the centering unit 14 may be movable in the direction of the workpiece central axis 2a. When the workpiece 2 is moved in the direction of the workpiece central axis 2a by the holding and moving unit 11, the axial runout of the workpiece 2 can be reliably suppressed by the centering unit 14, thereby further improving machining accuracy.

[0113] The plastic deformation method of this embodiment includes a workpiece holding step S100 and a plastic deformation step S110. In the workpiece holding step S100, the workpiece is held so that the angle between the workpiece central axis 2a and the horizontal plane is 45° or more. In the plastic deformation step S110, a plurality of forming rollers 121 are arranged so that the angle between the forming roller rotation axis 121a and the workpiece central axis 2a is 45° or less. The workpiece 2 is moved in the direction of the workpiece central axis 2a, and the outer surfaces of the plurality of forming rollers press against the workpiece 2 so as to sandwich it, thereby reducing the diameter of the workpiece 2. At the same time, the surface of the workpiece 2 formed by the forming rollers 121 is smoothed with a smoothing roller 131.

[0114] According to this, it is possible to suppress the rod-shaped workpiece 2 from sagging downward in the direction of gravity due to its own weight during the diameter reduction process in the plastic deformation process S110, and to suppress the marks left by holding the workpiece 2 from becoming defects in quality.

[0115] (Modified form of Embodiment 1) In the above embodiment 1, the centering portion 14 suppresses the axial runout of the workpiece 2 by having the centering member 141 press the upper end surface of the workpiece 2 downward in the direction of gravity. However, the centering member 141 may also suppress the axial runout of the workpiece 2 by fitting into the upper end of the workpiece 2. For example, if a protrusion is formed on the upper end surface of the workpiece 2 that projects toward the centering member 141, and a recess is formed on the lower surface of the centering member 141 into which the protrusion of the workpiece 2 is fitted, the centering portion 14 can suppress the axial runout of the workpiece 2.

[0116] The workpiece 2 (rough shape) formed by the plastic deformation apparatus 1 of this embodiment can be molded into various molded products, not only steering attachments which are automobile parts.

[0117] (Embodiment 2) Regarding the plastic deformation apparatus 200 of Embodiment 2, components identical to those of the plastic deformation apparatus 1 of Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted. The plastic deformation apparatus 200 shown in Figures 11 and 12 comprises a holding and moving section 210, a pair of forming roller units 12, a pair of leveling roller units 230, a centering section 240, and a control device (not shown).

[0118] The holding and moving part 210 holds the lower end of the workpiece 2 and moves the workpiece 2 in the direction of the workpiece central axis 2a. The holding and moving part 210 is a thrust unit having a receiving part 212 and a drive mechanism 113. The receiving part 212 has a shape in which the cylindrical part 111 and the receiving part 112 in Embodiment 1 are integrated.

[0119] The receiving portion 212 is a thrust member that receives the lower end surface 21 of the workpiece 2 from below in the direction of gravity and moves the workpiece 2 in the direction of gravity by being displaced in the direction of gravity. In other words, the receiving portion 212 supports the lower end surface 21 of the workpiece 2.

[0120] Each pair of molding roller units 12 includes a molding roller 121, a molding roller motor 122 (shown in Figure 1), and a molding roller actuator 123 (shown in Figure 1). The outer circumferential surface of the molding roller 121 has a convex arc shape in cross-section along the molding roller rotation axis 121a. The molding roller 121 has a predetermined width (width in the direction of the molding roller rotation axis 121a). The molding roller 121 protrudes most radially outward near the center position 121b in the width direction. For example, the molding roller 121 protrudes most radially outward at the center position 121b in the width direction.

[0121] A pair of leveling roller units 230 includes leveling rollers 231 and leveling roller actuators 132 (shown in Figure 2).

[0122] The outer surface of the leveling roller 231 has a cylindrical surface of the same outer diameter. The leveling roller 231 rotates around the leveling roller rotation axis 231a. The leveling roller rotation axis 231a is arranged parallel to the workpiece central axis 2a. The leveling roller 231 is rotatably supported on the support shaft 232. The support shaft 232 is supported at both ends by the holding parts 233. Therefore, the leveling roller 231 is supported at both ends.

[0123] The leveling roller 231 is restricted from moving relative to the holding portion 233 in the direction of the leveling roller rotation axis 231a. The leveling roller 231 is positioned within a range that includes the widthwise center position 121b of the molding roller 121.

[0124] The leveling roller 231 has a lower length L1 from the widthwise center position 121b of the molding roller 121 to the lower end of the leveling roller 231. The leveling roller 231 has an upper length L2 from the widthwise center position 121b of the molding roller 121 to the upper end of the leveling roller 231. The lower length L1 is longer than the upper length L2.

[0125] The centering unit 240 is a centering unit having a centering member 241 and a cylinder 142 (shown in Figure 1). The centering member 241 centers the workpiece 2 by restricting the radial position of the upper end of the workpiece 2 during plastic deformation. The centering member 241 is configured to allow axial movement relative to the upper end surface 22 of the workpiece 2 without restriction.

[0126] Next, a plastic deformation method using the plastic deformation apparatus 200 will be described. In the initial state shown in Figure 11, the forming roller 121 is rotated. Subsequently, as shown in Figure 13, the forming roller 121 is moved toward the workpiece 2, and the outer circumferential surface of the workpiece 2 is pressed by the forming roller 121. In this way, grooves 23 are formed on the outer circumferential surface of the workpiece 2, with the outer circumferential surface of the forming roller 121 transferred onto it. In other words, the diameter of the workpiece 2 is reduced.

[0127] At this time, in workpiece 2, as the groove 23 is formed, the material located in the groove 23 shifts. As a result, a lower expansion portion may be formed at the lower edge of the groove 23, which expands radially outward compared to the outer diameter before the groove 23 was formed. Similarly, an upper expansion portion may be formed at the upper edge of the groove 23.

[0128] However, because the leveling roller 231 is present, the leveling roller 231 levels the lower expansion portion, forming the lower leveling portion 24. Similarly, the leveling roller 231 levels the upper expansion portion, forming the upper leveling portion 25. When the leveling roller 231 is in contact with the outer circumferential surface of the workpiece 2 before the groove 23 is formed, the lower leveling portion 24 and the upper leveling portion 25 are flush with the rest of the outer circumferential surface of the workpiece 2. On the other hand, when the leveling roller 231 has a slight gap with the outer circumferential surface of the workpiece 2 before the groove 23 is formed, the lower leveling portion 24 and the upper leveling portion 25 protrude slightly from the rest of the outer circumferential surface of the workpiece 2. In Figures 13 and 14, the slightly protruding state is shown to make the positions of the lower leveling portion 24 and the upper leveling portion 25 clearer.

[0129] Here, the lower end surface 21 of the workpiece 2 is supported by the receiving portion 212. In other words, it is configured to restrict the length from the center position of the workpiece 2 where the diameter is reduced (corresponding to the center position 121b in the width direction of the forming roller 121) to the lower end surface 21 of the workpiece 2 from extending. Therefore, even if a groove 23 is formed, the distance between the center position of the workpiece 2 where the diameter is reduced (corresponding to the center position 121b in the width direction) and the lower end surface 21 of the workpiece 2 remains constant.

[0130] On the other hand, the upper end surface 22 of the workpiece 2 is not restricted by the centering portion 240. In other words, it is configured to allow the length from the center position of the workpiece 2 corresponding to the widthwise center position 121b of the forming roller 121 to the upper end surface 22 of the workpiece 2 to extend. Therefore, as the groove 23 is formed, the workpiece 2 extends upward by the amount of the material that was located in the groove 23. In other words, the position of the upper end surface 22 of the workpiece 2 rises.

[0131] Then, as shown in Figure 14, the molding roller 121 is moved further toward the workpiece 2, and the molding roller 121 is pressed further toward the outer circumferential surface of the workpiece 2. The groove 23 formed toward the outer circumferential surface of the workpiece 2 has a depth corresponding to the position of the outer circumferential surface of the molding roller 121.

[0132] As described above, the workpiece 2 is allowed to extend upward. Therefore, of the grooves 23 that form the diameter reduction portion of the workpiece 2, the upper corner portion 26 located closer to the upper end surface 22 of the workpiece 2 extends in length from the diameter reduction center position of the workpiece 2 (corresponding to the widthwise center position 121b) to the upper end surface 22 of the workpiece 2 as the diameter reduction progresses. Consequently, the upper corner portion 26 transitions from a state of contact with the molding roller 121, as shown in Figure 13, to a state of separation from the molding roller 121, as shown in Figure 14. In other words, a gap is formed between the upper groove surface of the groove 23 formed in the workpiece 2 and the molding roller 121. On the other hand, no gap is formed between the lower groove surface of the groove 23 formed in the workpiece 2 and the molding roller 121, and the lower groove surface of the groove 23 is in contact with the molding roller 121.

[0133] As shown in Figure 14, when the upper corner 26 of the workpiece 2 and the forming roller 121 are separated, the upper end of the leveling roller 231 is located below the upper corner 26 of the workpiece 2. In other words, at this time, the upper end of the leveling roller 231 is not in contact with the workpiece 2. This is because the upper end of the leveling roller 231 is positioned according to the position of the upper corner 26 of the workpiece 2 at the timing of separation between the upper corner 26 of the workpiece 2 and the forming roller 121.

[0134] Let's explain the effects. When the diameter of workpiece 2 is reduced, the portion of workpiece 2 below the widthwise center position 121b of the forming roller 121 does not elongate and is therefore always leveled and formed by the leveling roller 231. On the other hand, as the diameter of workpiece 2 is reduced, workpiece 2 elongates upward. If workpiece 2 elongates upward by an amount exceeding the upper length L2 of the leveling roller 231, it may not be leveled and formed by the leveling roller 231.

[0135] However, as workpiece 2 expands upward, at a certain point, radial expansion stops in the upper part of the tapered portion of workpiece 2, and only upward expansion occurs. If workpiece 2 separates from the forming roller 121 and expands upward, and the leveling roller 231 remains in contact with workpiece 2, the leveling roller 231 will exert a force that resists the upward expansion of workpiece 2. As a result, burrs may form on workpiece 2. However, as described above, by making the upper length L2 of the leveling roller 231 shorter than the lower length L1, the formation of burrs on workpiece 2 can be suppressed.

[0136] In particular, the upper end of the leveling roller 231 is positioned to correspond to the position of the upper corner 26 of the workpiece 2 at the separation timing between the upper corner 26 and the forming roller 121. The upper end of the leveling roller 231 is preferably positioned near the position of the upper corner 26 at the separation timing. For example, the upper end of the leveling roller 231 may coincide with the position of the upper corner 26 at the separation timing, or it may be positioned slightly above or below it. As a result, the formation of burrs on the workpiece 2 can be suppressed.

[0137] In particular, the upper length L2 should be set to a different length depending on the outer diameter of the workpiece 2. The separation timing described above differs depending on the outer diameter of the workpiece 2 (outer diameter before reduction). For example, the larger the outer diameter of the workpiece 2, the longer the upper length L2 should be. By setting the upper length to an appropriate length according to the outer diameter of the workpiece 2 in this way, burrs can be prevented from forming on the workpiece 2.

[0138] (Embodiment 3) The plastic deformation apparatus 300 of Embodiment 3 differs from that of Embodiment 2 in that it has a pair of leveling roller units 330. The other configurations are substantially the same.

[0139] As shown in Figures 15 and 16, the pair of leveling roller units 330 include a leveling roller 331 and a leveling roller actuator 132 (shown in Figure 2).

[0140] The outer surface of the leveling roller 331 has a conical surface that tapers towards the tip. The leveling roller rotation axis 331a is inclined at an angle θ with respect to the workpiece center axis 2a. The angle θ is set to, for example, 10 to 45°, preferably 20 to 35°. For example, the angle θ may be set to 30°.

[0141] Furthermore, the leveling roller 331 is rotatably cantilevered to the holding part 333 at a portion 332 near the base end of the conical surface. The leveling roller 331 is restricted from moving relative to the holding part 333 in the direction of the leveling roller rotation axis 331a.

[0142] Here, the base end of the conical surface of the leveling roller 331 may be located downwards or upwards. However, if the holding part 333 is located below the leveling roller 331, it is easier to construct a support for the leveling roller 331. Therefore, it is preferable for the base end of the conical surface of the leveling roller 331 to be located downwards.

[0143] In this case, the base end of the conical surface of the leveling roller 331 is located closer to the lower end surface 21 of the workpiece 2 than the widthwise center position 121b of the forming roller 121. Also, the tip of the conical surface of the leveling roller 331 constitutes a free end. The tip of the conical surface is located closer to the upper end surface 22 of the workpiece 2 than the widthwise center position 121b of the forming roller 121.

[0144] Furthermore, the leveling roller 331 is positioned within a range that includes the widthwise center position 121b of the molding roller 121. The leveling roller 331 has a lower length L1 from the widthwise center position 121b of the molding roller 121 to its lower end. The leveling roller 331 has an upper length L2 from the widthwise center position 121b of the molding roller 121 to its upper end. The lower length L1 is longer than the upper length L2.

[0145] In this case, the portion of the leveling roller 331 that is lower than the widthwise center position 121b of the forming roller 121 experiences a greater load than the portion that is higher. Therefore, by positioning the portion 332 near the base end of the conical surface of the leveling roller 331 downwards, the outer diameter of the lower portion of the leveling roller 331, which experiences a greater load, can be increased. This increases the rigidity of the leveling roller 331, and as a result, the displacement of the leveling roller 331 during leveling can be suppressed. Consequently, the accuracy of leveling on the workpiece 2 can be improved.

[0146] The plastic deformation method using the plastic deformation apparatus 300 is shown in Figures 15 and 17. It is substantially the same as that of Embodiment 2.

[0147] (Embodiment 4) The plastic deformation apparatus 400 of Embodiment 4 differs from that of Embodiment 2 in that it has a pair of leveling roller units 430. The other configurations are substantially the same.

[0148] As shown in Figure 18, the pair of leveling roller units 430 includes a lower leveling roller 431, an upper leveling roller 432, and a leveling roller actuator 132 (shown in Figure 2).

[0149] The outer circumferential surface of the lower leveling roller 431 has a cylindrical surface of the same outer diameter. The lower leveling roller 431 rotates around the leveling roller rotation axis 431a. The leveling roller rotation axis 431a is arranged parallel to the workpiece central axis 2a. The lower leveling roller 431 is rotatably supported by the support shaft 433. The support shaft 433 is supported at both ends by the holding parts 434. Therefore, the lower leveling roller 431 is supported at both ends.

[0150] The lower leveling roller 431 is restricted from moving downward relative to the holding portion 434. Therefore, the lower leveling roller 431 is restricted from moving downward relative to the molding roller 121. The lower leveling roller 431 is positioned within a range that includes the widthwise center position 121b of the molding roller 121. In other words, the upper end surface of the lower leveling roller 431 is located above the widthwise center position 121b of the molding roller 121, and the lower end surface is located below the widthwise center position 121b.

[0151] Therefore, the lower leveling roller 431 levels the lower expansion portion, which is located closer to the lower end surface 21 of the workpiece 2 than the center position of the workpiece 2's diameter reduction (corresponding to the widthwise center position 121b of the forming roller 121) as the workpiece 2 is reduced in diameter. However, in the initial stages of the workpiece 2's diameter reduction, the lower leveling roller 431 levels the upper expansion portion, which is located closer to the upper end surface 22 of the workpiece 2 than the center position of the workpiece 2's diameter reduction (corresponding to the widthwise center position 121b of the forming roller 121) as the workpiece 2 is reduced in diameter.

[0152] The outer circumferential surface of the upper leveling roller 432 has a cylindrical surface of the same outer diameter. The upper leveling roller 432 is above the lower leveling roller 431 and is rotatably supported on the support shaft 433. Therefore, the upper leveling roller 432 rotates around the leveling roller rotation shaft 431a.

[0153] Furthermore, the upper leveling roller 432 is positioned to be relatively movable relative to the forming roller 121 in the axial direction of the workpiece central axis 2a. Specifically, the upper leveling roller 432 is provided to be movable in the axial direction along the support shaft 433. In other words, when the lower end surface of the upper leveling roller 432 is in contact with the upper end surface of the lower leveling roller 431, the upper leveling roller 432 becomes movable upward.

[0154] Then, during the process of reducing the diameter of workpiece 2, the upper leveling roller 432 levels the upper expansion portion, which is located closer to the upper end surface 22 of workpiece 2 than the center position of the diameter reduction of workpiece 2 (corresponding to the widthwise center position 121b of the forming roller 121) as workpiece 2 is reduced in diameter. Furthermore, the upper leveling roller 432 moves upward relative to the lower leveling roller 431 as the upper expansion portion moves axially.

[0155] Next, a plastic deformation method using the plastic deformation apparatus 400 will be described. As shown in Figure 19, the forming roller 121 is moved toward the workpiece 2, and the outer surface of the workpiece 2 is pressed by the forming roller 121. In this way, grooves 23 are formed on the outer surface of the workpiece 2, with the outer surface of the forming roller 121 transferred onto it. In other words, the diameter of the workpiece 2 is reduced.

[0156] At this time, the lower leveling roller 431 levels and shapes the lower expansion section, forming the lower leveling section 24. For the upper expansion section, the lower leveling roller 431 levels and shapes the upper expansion section in the initial stages of diameter reduction, forming the upper leveling section 25. After that, the upper leveling roller 432 levels and shapes the upper expansion section, forming the upper leveling section 25.

[0157] As the molding roller 121 is pushed onto the workpiece 2, the lower leveling section 24 moves downward. However, the lower leveling roller 431 is restricted from moving downward, so even while the lower leveling section 24 is moving downward, the lower leveling roller 431 does not move downward and continues to level the lower expansion section.

[0158] Meanwhile, as the molding roller 121 is pressed into the workpiece 2, the upper leveling section 25 moves upward. At this point, the upper leveling roller 432 is permitted to move upward. Therefore, as the upper leveling section 25 moves upward, the upper leveling roller 432 also moves upward.

[0159] Then, as shown in Figure 20, the molding roller 121 is moved further toward the workpiece 2, and the molding roller 121 is pressed further toward the outer surface of the workpiece 2. As a result, the upper leveling roller 432 moves further upward along with the movement of the upper leveling section 25. Therefore, as the upper expansion section is leveled and molded, the formation of burrs on the workpiece 2 can be suppressed.

[0160] Furthermore, the lower leveling roller 431 is rotatably supported on the support shaft 433 and its downward movement relative to the support shaft 433 is restricted, while the upper leveling roller 432 is rotatably supported on the support shaft 433 and is provided to be axially movable along the support shaft. This allows the lower leveling roller 431 and the upper leveling roller 432 to be arranged coaxially, and enables the upper leveling roller 432 to be moved upward. [Explanation of Symbols]

[0161] 1, 200, 300, 400 Plastic processing equipment 2 Work 2a Workpiece central axis 11, 210 Holding and moving part 14, 240 Alignment part 21 Lower end surface of the workpiece 22 Upper end face of the workpiece 26 Upper corner 111 Cylindrical part 112, 212 receiving part 113 Drive mechanism 121 Molding Roller 121a Molding roller rotation shaft 131, 231, 331 leveling rollers 431 Lower leveling roller 432 Upper leveling roller 232, 433 Support shaft S100 Workpiece Holding Process S110 Plastic working process

Claims

1. A holding and moving unit that holds the workpiece such that the angle between the central axis of the rod-shaped workpiece and the horizontal plane is 45° or more, and moves the workpiece in the direction of the central axis of the workpiece, A plurality of molding rollers are arranged such that the angle between the molding roller rotation axis and the central axis of the workpiece is 45° or less, and the outer surfaces of the molding rollers press against the workpiece while rotating, thereby reducing the diameter of the workpiece, and the angle between the molding roller rotation axis and the central axis of the workpiece is 45° or less. A plastic deformation apparatus comprising: a leveling roller for leveling the surface of the workpiece formed by the molding roller.

2. The plastic deformation apparatus according to claim 1, wherein the holding and moving part has a receiving part that receives the lower end surface of the workpiece from below in the direction of gravity.

3. The device is configured to restrict the length from the center position of the workpiece's diameter reduction, which corresponds to the widthwise center position of the molding roller, to the lower end surface of the workpiece, and to allow the length from the center position of the workpiece's diameter reduction to the upper end surface of the workpiece to extend. The aforementioned leveling roller is The molding roller is arranged in a range that includes the center position in the width direction, The lower length of the molding roller is from the center position in the width direction to the lower end of the leveling roller, The upper length from the center position in the width direction of the molding roller to the upper end of the leveling roller, The plastic deformation apparatus according to claim 2, wherein the lower length is longer than the upper length.

4. The upper corner portion of the reduced diameter portion of the workpiece, located closer to the upper end surface, transitions from a state of contact with the molding roller to a state of separation as the length from the center of the reduced diameter of the workpiece to the upper end surface of the workpiece increases due to the progress of the reduction in diameter of the workpiece. The plastic deformation apparatus according to claim 3, wherein the upper end of the leveling roller is positioned according to the position of the upper corner of the workpiece at the timing of separation between the upper corner of the workpiece and the forming roller.

5. The plastic deformation apparatus according to claim 4, wherein the upper length is set to a different length depending on the outer diameter of the workpiece.

6. The rotation axis of the leveling roller is arranged parallel to the central axis of the workpiece. The plastic deformation apparatus according to any one of claims 3 to 5, wherein the leveling roller is supported by both sides.

7. The plastic deformation apparatus according to claim 6, wherein the outer circumferential surface of the leveling roller has a cylindrical surface.

8. The rotation axis of the leveling roller is inclined with respect to the central axis of the workpiece. The plastic deformation apparatus according to any one of claims 3 to 5, wherein the leveling roller is cantilevered.

9. The plastic deformation apparatus according to claim 8, wherein the outer circumferential surface of the leveling roller has a conical surface.

10. The aforementioned leveling roller is The portion of the conical surface near its base is cantilevered, and the base of the conical surface is located closer to the lower end surface of the workpiece than the widthwise center position of the forming roller. The plastic deformation apparatus according to claim 9, wherein the tip of the conical surface constitutes a free end, and the tip of the conical surface is located closer to the upper end surface of the workpiece than the widthwise center position of the forming roller.

11. The device is configured to restrict the length from the center position of the workpiece's diameter reduction, which corresponds to the widthwise center position of the molding roller, to the lower end surface of the workpiece in the axial direction, and to allow the length from the center position of the workpiece's diameter reduction to the upper end surface of the workpiece in the axial direction. The aforementioned leveling roller is A lower leveling roller whose downward movement is restricted relative to the molding roller, and which levels the lower expansion portion located closer to the lower end surface of the workpiece than the center of the workpiece's diameter reduction when the workpiece is reduced in diameter, The plastic deformation apparatus according to claim 2, further comprising: an upper leveling roller positioned to be movable upward relative to the forming roller, which levels the upper expansion portion located closer to the upper end face of the workpiece than the center of the diameter reduction of the workpiece when the workpiece is reduced in diameter, and which moves upward relative to the lower leveling roller as the upper expansion portion moves in the axial direction.

12. The lower leveling roller is rotatably supported on a support shaft and its downward movement is restricted relative to the support shaft. The plastic deformation apparatus according to claim 11, wherein the upper leveling roller is rotatably supported on the support shaft and is provided to be movable upward along the support shaft.

13. The plastic deformation apparatus according to claim 2, wherein the holding and moving part has a drive mechanism that moves the workpiece in the direction of the workpiece central axis by driving the receiving part in the direction of the workpiece central axis.

14. The plastic deformation apparatus according to claim 12 or 13, wherein the receiving portion is rotatable by a drive around the central axis of the workpiece.

15. The holding and moving part has a cylindrical portion into which the workpiece is inserted. The plastic deformation apparatus according to claim 13, wherein the receiving portion moves relative to the cylindrical portion in the direction of the central axis of the workpiece.

16. The plastic deformation apparatus according to claim 15, wherein the receiving portion is movable to a position that protrudes upward in the direction of gravity from the upper end of the cylindrical portion in the direction of gravity.

17. The plastic deformation apparatus according to claim 15, wherein the receiving portion is capable of driven rotation around the central axis of the workpiece.

18. The plastic deformation apparatus according to claim 2, wherein the holding and moving part has a cylindrical part into which the workpiece is inserted.

19. The plastic deformation apparatus according to claim 15 or 18, wherein the cylindrical portion is rotatable by a drive around the central axis of the workpiece.

20. The plastic deformation apparatus according to claim 2, further comprising a centering unit that suppresses axial runout of the workpiece by regulating the radial position of the upper end of the workpiece.

21. The plastic deformation apparatus according to claim 20, wherein the centering part suppresses the axial runout of the workpiece by pressing the upper end surface of the workpiece downward in the direction of gravity.

22. The plastic deformation apparatus according to claim 21, wherein the centering part is capable of driven rotation around the central axis of the workpiece.

23. The plastic deformation apparatus according to claim 21, wherein the centering portion is movable in the direction of the central axis of the workpiece.

24. A workpiece holding step in which the workpiece is held such that the angle between the central axis of the rod-shaped workpiece and the horizontal plane is 45° or more, A plastic deformation method comprising: a plastic deformation step of arranging a plurality of molding rollers that rotate around a molding roller rotation axis such that the angle between the molding roller rotation axis and the workpiece central axis is 45° or less, reducing the diameter of the workpiece by pressing the outer surfaces of the plurality of molding rollers against the workpiece while moving the workpiece in the direction of the workpiece central axis, and smoothing the surface of the workpiece formed by the molding rollers with a smoothing roller.

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