Method for forming a toothed cylinder

Abstract

To reduce the possibility that cracks are generated during processing.SOLUTION: A toothed cylindrical body formation method includes a cylindrical body formation step S300, and a tooth formation step S302. In the cylindrical body formation step S300, a cylindrical body is formed so as to be divided into a tooth formation section, a small outer diameter section and a step section 112. In the tooth formation step S302, the tooth formation section is pressed to a die in a state in which the step section is supported and a part on the other end side of the cylindrical body rather than the step section in the cylindrical body floats. Thereby, a tooth of a gear is formed in the tooth formation section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for forming a toothed cylinder. [Background technology]

[0002] Patent Document 1 discloses a method for forming an internal gear. In this method, a material is attached to a mandrel having teeth on its outer periphery, and a drawing roller is pressed against the material to press it against the mandrel to form a cylindrical internal gear. In this method, a drawing roller is used that has two arcuate portions that come into contact with the material, and the outer diameter of the arcuate portion that comes into contact with the material later is larger than the outer diameter of the arcuate portion that comes into contact with the material first. A cylindrical internal gear is formed by moving the drawing roller in a direction parallel to the axis of the mandrel. According to the method for forming an internal gear disclosed in Patent Document 1, even when forming an internal gear by plastic processing a thin-walled material, undercutting does not occur and the cycle time can be shortened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-050905 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the invention disclosed in Patent Document 1 has a problem in that cracks tend to occur in the material during processing.

[0005] It is an object of the present invention to provide a method for forming a toothed cylinder which reduces the possibility of cracks occurring during processing. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for forming a toothed cylinder includes a cylinder forming step S300 and a teeth forming step S302. In the cylinder forming step S300, a metal plate is subjected to plastic processing to form a cylinder 12. In the teeth forming step S302, gear teeth are formed in a tooth forming section 30. The tooth forming section 30 is a section disposed at one end of the cylinder 12. The gear teeth are formed by plastic processing. In the cylinder forming step S300, the cylinder 12 is formed so as to be divided into a tooth forming section 30, a small outer diameter section 110, and a step section 112. The small outer diameter section 110 is disposed on the other end side of the cylinder 12 relative to the tooth forming section 30. The small outer diameter section 110 has a smaller outer diameter than the tooth forming section 30. The step section 112 is disposed between the tooth forming section 30 and the small outer diameter section 110. The step section 112 becomes a step between the tooth forming section 30 and the small outer diameter section 110. In the tooth forming step S302, the tooth forming section 30 is subjected to plastic processing in a state in which the step section 112 is supported and the portion of the cylinder 12 on the other end side of the cylinder 12 beyond the step section 112 is suspended in the air.

[0007] When the tooth forming section 30 is subjected to plastic processing in the tooth forming step S302, the step section 112 is supported and the part of the cylinder 12 on the other end side is suspended in the air from the step section 112. Since the part of the cylinder 12 on the other end side is suspended in the air from the step section 112, the possibility of plastic deformation occurring in the part of the cylinder 12 on the other end side from the step section 112 is low. The plastic deformation is caused by internal stress that occurs when the tooth forming section 30 is subjected to plastic processing and by the movement of the part of the cylinder 12 on the other end side being restricted. Since the possibility of plastic deformation occurring is low, the possibility of cracks occurring due to the plastic deformation is low. As a result, the possibility of cracks occurring during processing is low.

[0008] The cylindrical body forming step S300 includes a base material forming step S320, a small outer diameter section forming step S322, and a step forming step S324. do.In the preform forming step S320, a cylindrical preform 10 is formed by plastic processing of a metal plate. In the small outer diameter section forming step S322, the other end of the preform 10 is plastically processed so that the outer diameter of the other end of the preform 10 is reduced compared to the outer diameter of the one end of the preform 10. This forms the small outer diameter section 110. In the step forming step S324, a step section 112 is formed. In this case, in the step forming step S324, the step surface forming roller 74 presses and smooths the area between the tooth forming section 30 and the small outer diameter section 110, so that the step surface forming roller 74 forms a step surface in the step section 112. do.

[0009] In the step forming step S324, the step surface forming roller 74 presses and smooths the gap between the tooth forming section 30 and the small outer diameter section 110. As a result, the step surface forming roller 74 forms a step surface in the step section 112. When a step surface is formed in the step section 112 by pressing and smoothing, it becomes possible to support the step surface in the tooth forming step S302. When the step surface formed by pressing and smoothing is supported, the possibility of a large force being applied to a part of the cylindrical body 12 is reduced compared to when the step section 112 is supported by a part of the unevenness remaining between the tooth forming section 30 and the small outer diameter section 110 due to not being pressed and smoothed. When this possibility is reduced, the possibility of plastic deformation occurring in the step section 112 and the part of the cylindrical body 12 on the other end side thereof is reduced. Since the possibility of plastic deformation is reduced, the possibility of cracks occurring due to the plastic deformation is reduced. As a result, the possibility of cracks occurring during processing is reduced.

[0010] Alternatively, it is preferable that the stepped surface forming roller 74 is rotatable about an axis extending in a direction from the other end of the preform 10 to one end of the preform 10. In this case, it is preferable that the preform 10 rotates about an axis extending along the axis of rotation of the stepped surface forming roller 74 in the step forming step S324.

[0011] When the preform 10 rotates about an axis aligned with the rotation axis of the stepped surface forming roller 74, it becomes easier for the stepped surface forming roller 74 to roll between the tooth forming section 30 and the small outer diameter section 110 when pressing and smoothing between them, compared to the case described below. This case is when the rotation axis of the preform 10 is not aligned with the rotation axis of the stepped surface forming roller 74. When the stepped surface forming roller 74 rolls more easily, it becomes more difficult for the stepped surface forming roller 74 to apply frictional force between them, compared to when the stepped surface forming roller 74 slides between them when pressing and smoothing between them. When frictional force is less easily applied, there is less possibility that the surface between them will be adversely affected by frictional heat.

[0012] Alternatively, in the above-described small outer diameter section forming step S322, it is preferable that the other end of the preformed material 10 is subjected to plastic processing as described below. That is, the stepped surface forming roller 74 moves in a direction from the other end of the preformed material 10 toward one end of the preformed material 10 while being pressed against the outer periphery of the other end of the preformed material 10, and the preformed material 10 rotates about an axis that is aligned with the rotation axis of the stepped surface forming roller 74.

[0013] The stepped surface forming roller 74 moves in a direction from the other end of the preform 10 to one end of the preform 10 while being pressed against the outer periphery of the other end of the preform 10. The stepped surface forming roller 74 is rotatable about an axis that runs along the direction from the other end of the preform 10 to one end of the preform 10. The preform 10 rotates about an axis that runs along the axis of rotation of the stepped surface forming roller 74. As a result, the other end of the preform 10 is spread out in a spiral shape by the stepped surface forming roller 74. As a result, the difference in the degree of plastic deformation between the various points that are spread out is smaller than when the preform 10 is spread out linearly from the other end to one end. Because the difference in the degree is smaller, the possibility of distortion occurring in the preform 10 due to the difference in the degree is reduced. Effect of the Invention

[0014] The present invention reduces the likelihood of cracks occurring during processing. [Brief description of the drawings]

[0015] [Figure 1] 2 is a flowchart showing each step of a method for forming a toothed cylinder according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a conceptual diagram showing the appearance of a base material according to one embodiment of the present invention. [Diagram 3] 1 is a conceptual diagram showing the configuration of an outer diameter reduction processing device according to one embodiment of the present invention; [Figure 4] 1 is a conceptual diagram showing an outer diameter reduction processing device performing a small outer diameter section forming process according to one embodiment of the present invention. FIG. [Diagram 5] 11 is a conceptual diagram showing a state in which the stepped surface forming roller has moved to near the end of the section scheduled to reduce the outer diameter in one embodiment of the present invention. FIG. [Figure 6] FIG. 2 is a conceptual diagram showing the appearance of a cylindrical body according to one embodiment of the present invention. [Figure 7] 1 is a conceptual diagram showing a configuration of a tooth formation device according to one embodiment of the present invention. [Figure 8] FIG. 2 is a conceptual diagram showing a tooth forming device performing a tooth forming process in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed descriptions thereof will not be repeated.

[0017] [Steps of forming a toothed cylinder] 1 is a flow chart showing each step of the method for forming a toothed cylinder according to the present embodiment. Each step of the method for forming a toothed cylinder according to the present embodiment will be described with reference to FIG.

[0018] The toothed cylinder forming method according to this embodiment includes a cylinder forming step S300 and a teeth forming step S302.

[0019] In the cylinder forming process S300, the metal plate is plastically processed to form the cylinder 12. In this embodiment, the cylinder forming process S300 includes a preform forming process S320, a small outer diameter section forming process S322, and a step forming process S324. In the preform forming process S320, a cylindrical preform 10 is formed by plastic processing the metal plate. In the small outer diameter section forming process S322, the other end of the preform 10 is plastically processed so that the outer diameter of the other end of the preform 10 is reduced compared to the outer diameter of the one end of the preform 10. In the step forming process S324, a step surface forming roller 74 presses and smooths a section of the preform 10, which will be described later.

[0020] In the tooth forming step S302, the gear teeth are formed by plastic processing. In this embodiment, the gear teeth are formed at one end of the base material 10.

[0021] [Description of the operations in each step when the toothed cylinder forming method is carried out] FIG. 2 is a diagram showing the appearance of the base material 10 according to this embodiment. FIG. 3 is a conceptual diagram showing the configuration of the outer diameter reduction processing device 50 according to this embodiment. FIG. 4 is a conceptual diagram showing the outer diameter reduction processing device 50 during the small outer diameter section forming step S322. FIG. 5 is a conceptual diagram showing a state in which the step surface forming roller 74 has moved to the vicinity of the end of the outer diameter reduction planned section 32. FIG. 6 is a conceptual diagram showing the appearance of the cylindrical body 12 according to this embodiment. FIG. 7 is a conceptual diagram showing the configuration of the tooth forming device according to this embodiment. FIG. 8 is a conceptual diagram showing the tooth forming device during the tooth forming step S302. Based on FIG. 1 to FIG. 8, the specific contents of each step when the toothed cylindrical body forming method according to this embodiment is carried out will be described.

[0022] A person who carries out the toothed cylinder forming method according to this embodiment (hereinafter referred to as the "practitioner") forms a cylindrical preform 10 by plastic processing of a metal plate (S320). As shown in FIG. 2, the preform 10 according to this embodiment has an opening forming portion 20, a body portion 22, and a bottom portion 24. The opening forming portion 20 is an annular surface disposed at one end of the body portion 22. The provision of the opening forming portion 20 results in the preform 10 having an opening. The body portion 22 is a portion of the preform 10 that is mainly to be processed. The body portion 22 forms a curved surface on the outer periphery of the preform 10. The bottom portion 24 is disposed at the other end of the body portion 22. The bottom portion 24 closes the other end of the body portion 22. The body portion 22 has a tooth forming section 30 and an outer diameter reduction planned section 32. The tooth forming section 30 is disposed at one end of the body portion 22. Gear teeth are formed in the tooth forming section 30. The section 32 intended to reduce the outer diameter is disposed on the other end side of the body portion 22 as viewed from the tooth forming section 30. The section 32 intended to reduce the outer diameter is continuous with the tooth forming section 30. The method for forming the base material 10 according to this embodiment is the same as a known plastic processing method, and therefore detailed description thereof will not be repeated here.

[0023] Once the preform 10 is formed, the practitioner mounts the preform 10 on an outer diameter reduction processing apparatus 50. As shown in Fig. 3, the outer diameter reduction processing apparatus 50 according to this embodiment includes a mandrel 70, a preform pressing member 72, a stepped surface forming roller 74, a pressing member holder 76, a stepped surface forming roller holder 78, a reduction processing holder base 80, a coil spring 82, a mandrel rotation device (not shown), and a lowering drive device (not shown).

[0024] The mandrel 70 is a cylindrical member with a rounded tip. The preform 10 is attached so as to cover the tip of the mandrel 70. The mandrel 70 is rotatable about its central axis.

[0025] The preform pressing member 72 is a thick, disk-shaped member with a concave surface facing the mandrel 70. The preform pressing member 72 is also rotatable about its own central axis. The central axis of the mandrel 70 and the central axis of the preform pressing member 72 are connected. As a result, the mandrel 70 and the preform pressing member 72 are rotatable about the same axis.

[0026] The stepped surface forming roller 74 is disposed so as to be freely movable along the side surface of the mandrel 70. The stepped surface forming roller 74 is also freely rotatable about its own central axis. The stepped surface forming roller 74 is a member for plastically deforming the base material 10.

[0027] The pressing member holder 76 holds the preform pressing member 72. When the pressing member holder 76 receives a force, it moves the preform pressing member 72 by the force.

[0028] The stepped surface forming roller holder 78 rotatably holds the stepped surface forming roller 74. When a force is applied to the stepped surface forming roller holder 78, the stepped surface forming roller 74 is moved by the force.

[0029] The reducing processing holder base 80 movably holds the pressing member holder 76. The stepped surface forming roller holder 78 is fixed to the reducing processing holder base 80. When the reducing processing holder base 80 receives the above-mentioned force and moves, the stepped surface forming roller holder 78 also moves.

[0030] The coil spring 82 connects the pressing member holder 76 to the reducing processing holder base 80. When the reducing processing holder base 80 receives the above-mentioned force and moves, the coil spring 82 presses the pressing member holder 76. When the pressed pressing member holder 76 moves, the base material pressing member 72 also moves.

[0031] The mandrel rotating device drives the mandrel 70 so that it rotates. The lowering drive device drives the reducing holder base 80 so that it descends. This drive causes the reducing holder base 80 to receive the above-mentioned force. As a result, the blank pressing member 72 approaches the mandrel 70. The stepped surface forming roller 74 moves along the side of the mandrel 70.

[0032] When the preform 10 is attached to the mandrel 70 of the outer diameter reduction processing device 50, the operator starts the lowering drive device. The started lowering drive device drives the reducing holder base 80. The reducing holder base 80 receives force from this drive and descends. This causes the pressing member holder 76 and the stepped surface forming roller holder 78 to also descend. When the pressing member holder 76 descends, the preform pressing member 72 presses the preform 10 against the mandrel 70. The stepped surface forming roller holder 78 moves the stepped surface forming roller 74 close to the preform 10. When the preform 10 is pressed against the mandrel 70 and the stepped surface forming roller 74 is close to the preform 10, the operator starts the mandrel rotation device. The started mandrel rotation device rotates the mandrel 70. Accordingly, the preform 10 rotates. The preform pressing member 72 also rotates. Therefore, the preform pressing member 72 is rotatable. When the mandrel 70, preform 10, and preform pressing member 72 rotate, the operator controls the lowering drive device so that the reducing holder base 80 further descends. When the reducing holder base 80 further descends as a result of this control, the coil spring 82 contracts. Since the coil spring 82 contracts, the preform pressing member 72 does not move, and the stepped surface forming roller 74 moves toward the base of the mandrel 70. In other words, the stepped surface forming roller 74 moves freely on its own axis in a direction from the other end of the preform 10 toward one end of the preform 10. Accordingly, the stepped surface forming roller 74 is pressed against the outer periphery of the other end of the preform 10 as shown in FIG. 4. As the step surface forming roller 74 moves, the section of the preform 10 between the bottom portion 24 and the teeth forming section 30 is plastically worked so that the outer diameter is reduced (S322). As a result, the other end of the preform 10 is plastically worked.

[0033] Thereafter, the step surface forming roller 74 moves to the vicinity of the end of the section 32 where the outer diameter is to be reduced. During this time, the base material 10 continues to rotate. FIG. 5 is a diagram showing a state where the step surface forming roller 74 has moved to the vicinity of the end of the section 32 where the outer diameter is to be reduced. In the present embodiment, the step surface forming roller 74 has a roller tapered surface 90. Accordingly, the roller tapered surface 90 of the step surface forming roller 74 is pressed against the end of the section 32 where the outer diameter is to be reduced. By pressing the roller tapered surface 90, the step surface forming roller 74 presses and smoothes the end of the section 32 where the outer diameter is to be reduced. Since the end of the section 32 where the outer diameter is to be reduced is pressed and smoothed, a tapered surface is formed at the end of the section 32 where the outer diameter is to be reduced. Since the tapered surface is formed, a step is formed at the end of the section 32 where the outer diameter is to be reduced (S324). When the step is formed, the base material 10 becomes a cylindrical body 12. The operator removes the cylindrical body 12 from the outer diameter reduction processing device 50.

[0034] As is clear from FIG. 6, in the cylindrical body 12 according to this embodiment, the portion of the outer diameter reduction planned section 32 of the preform 10 becomes a small outer diameter section 110 and a step section 112. The small outer diameter section 110 is a section of the outer diameter reduction planned section 32 that is formed by the passage of the step surface forming roller 74. As a result, the small outer diameter section 110 is disposed closer to the bottom 24 than the tooth formation section 30. The small outer diameter section 110 has a smaller outer diameter than the tooth formation section 30. The step section 112 is a section that is formed by the end of the outer diameter reduction planned section 32 being pressed and leveled by the roller taper surface 90 of the step surface forming roller 74. As a result, the step section 112 is disposed between the tooth formation section 30 and the small outer diameter section 110. The step section 112 forms a step between the tooth formation section 30 and the small outer diameter section 110. As a result, in the cylindrical body forming step S300, the body portion 22 of the preform 10 is plastically worked so as to be divided into the teeth forming section 30, the small outer diameter section 110, and the step section 112.

[0035] When the cylindrical body 12 is removed from the outer diameter reduction processing device 50, the practitioner attaches the cylindrical body 12 to the external teeth forming device 130. As shown in Fig. 7, the external teeth forming device 130 according to this embodiment includes a base 150, a cylindrical body holding member 152, a tooth forming member 154, an anti-swaying member 156, a diameter expanding roller 158, a diameter expanding roller holding body 160, a teeth forming holder base 162, a coil spring 164, a base rotation device (not shown), and a lowering drive device (not shown).

[0036] The base 150 is a cylindrical member with a flat tip. The bottom 24 of the cylindrical body 12 faces the base 150 with a gap therebetween. The base 150 is rotatable about its central axis.

[0037] The cylindrical body holding member 152 is disposed so as to cover the pedestal 150. A hole is formed in the center of the cylindrical body holding member 152. As a result, the tip of the pedestal 150 is exposed through the hole. The cylindrical body 12 enters the hole. Accordingly, the cylindrical body holding member 152 supports the cylindrical body 12 on the edge of the hole. Therefore, the edge of the hole has a tapered surface.

[0038] The tooth forming member 154 is fixed to the cylindrical body holding member 152 so as to be placed thereon. A hole is formed in the center of the tooth forming member 154. The hole is connected to a hole formed in the cylindrical body holding member 152. As a result, the tip of the base 150 is exposed through the hole. The cylindrical body 12 enters the hole. Gear teeth are formed on the inner peripheral surface of the hole. As described above, the cylindrical body holding member 152 supports the cylindrical body 12 at the edge of the hole formed in its center. Therefore, the inner peripheral surface of the hole formed in the tooth forming member 154 faces the tooth forming section 30 of the cylindrical body 12.

[0039] The anti-swaying member 156 is a member having a circular plate-shaped contact portion at the tip of a cylindrical shaft portion. The outer edge of the contact portion is curved. The anti-swaying member 156 is rotatable around the shaft portion.

[0040] The diameter expanding roller 158 is disposed so as to be movable along the inner circumferential surface of the hole formed in the tooth forming member 154. The diameter expanding roller 158 is rotatable about the central axis of the diameter expanding roller 158 itself. The diameter expanding roller 158 is a member for plastically deforming the cylindrical body 12.

[0041] The diameter expanding roller holder 160 rotatably holds the diameter expanding roller 158. When a force is applied to the diameter expanding roller holder 160, the diameter expanding roller 158 also moves in response to the movement of the diameter expanding roller holder 160.

[0042] The diameter expanding roller holder 160 is fixed to the teeth formation holder base 162. When the teeth formation holder base 162 receives a force and moves, the diameter expanding roller holder 160 also moves.

[0043] The coil spring 164 connects the anti-swaying member 156 to the holder base 162. When the holder base 162 receives a force and moves, the coil spring 164 pushes the anti-swaying member 156. The pushed anti-swaying member 156 moves.

[0044] The base rotation device drives the base 150, the cylindrical body holding member 152, and the tooth forming member 154 so as to rotate them. The lowering drive device drives the teeth forming holder base 162 so as to lower it. This drive causes the teeth forming holder base 162 to receive the force described above. As a result, the anti-swaying member 156 approaches the base 150. The expanding roller 158 moves along the inner circumferential surface of the hole formed in the tooth forming member 154.

[0045] The cylindrical body 12 is attached to the external teeth forming device 130 so as to be placed on the base 150. When the cylindrical body 12 is attached to the external teeth forming device 130, the practitioner starts the lowering drive device. When the lowering drive device is started, the anti-swaying member 156 presses the bottom 24 of the cylindrical body 12. Meanwhile, the practitioner starts the base rotation device. The started base rotation device rotates the base 150, the cylindrical body holding member 152, and the tooth forming member 154. As a result, the cylindrical body 12 rotates. The anti-swaying member 156 also rotates. When they rotate, the practitioner controls the lowering drive device to move the expanding roller 158 toward the base 150. As a result, the expanding roller 158 is pressed against the rotating cylindrical body 12 as shown in FIG. 8. As the expanding roller 158 moves, the tooth forming section 30 is expanded. The outer peripheral surface of the expanded tooth forming section 30 is pressed against the inner peripheral surface of a hole formed in the tooth forming member 154. As a result, gear teeth are formed on the outer periphery of the tooth forming section 30 (S302). At this time, the step section 112 is supported. The small outer diameter section 110 and the bottom portion 24 are suspended in mid-air. In this state, the outer periphery of the tooth forming section 30 is pressed against the inner peripheral surface of a hole formed in the tooth forming member 154. When gear teeth are formed on the outer periphery of the tooth forming section 30, the externally toothed cylinder according to this embodiment is completed.

[0046] [Effects of the method for forming a toothed cylinder according to this embodiment] According to the toothed cylinder forming method of this embodiment, when the tooth forming section 30 is pressed against the gear tooth form, the step section 112 is supported. At this time, the small outer diameter section 110 and the bottom 24 are suspended in the air. Since these parts are suspended in the air, it is less likely that internal stress will be applied to these parts while their movement is restricted. When this possibility is reduced, it is less likely that plastic deformation will occur in these parts. Since it is less likely that plastic deformation will occur in these parts, it is less likely that cracks will occur due to the plastic deformation. As a result, it is less likely that cracks will occur during processing.

[0047] Further, according to the toothed cylinder forming method of this embodiment, in the step forming step S324, the roller taper surface 90 of the step surface forming roller 74 presses and smooths the gap between the tooth forming section 30 and the small outer diameter section 110. As a result, the step surface forming roller 74 forms a tapered surface in the step section 112. When the tapered surface is formed in the step section 112, it becomes possible to support the tapered surface in the tooth forming step S302. When the tapered surface is supported, the possibility of a large force being applied to a part of the cylinder 12 is reduced compared to when the step section 112 is supported by a part of the unevenness remaining between the tooth forming section 30 and the small outer diameter section 110 due to not being pressed and smoothed. When this possibility is reduced, the possibility of plastic deformation occurring in the step section 112 and the part of the cylinder 12 on the other end side thereof is reduced. Since the possibility of plastic deformation is reduced, the possibility of cracks occurring due to the plastic deformation is reduced. As a result, the possibility of cracks occurring during processing is reduced.

[0048] Furthermore, according to the method for forming a toothed cylindrical body of this embodiment, the base material 10 rotates about an axis that is aligned with the rotation axis of the stepped surface forming roller 74. When the base material 10 rotates, the stepped surface forming roller 74 can more easily roll between the tooth forming section 30 and the small outer diameter section 110 when pressing and smoothing them, compared to when the rotation axis of the base material 10 is not aligned with the rotation axis of the stepped surface forming roller 74. When the stepped surface forming roller 74 rolls more easily, it becomes more difficult for the stepped surface forming roller 74 to apply a frictional force between them, compared to when the stepped surface forming roller 74 slides between them when pressing and smoothing them. When frictional force is less easily applied, the surface between them is less likely to be adversely affected by frictional heat.

[0049] Furthermore, in the method for forming a toothed cylinder according to this embodiment, the preform 10 rotates on its axis in the small outer diameter section forming step S322. When the preform 10 rotates on its axis, the other end of the preform 10 is expanded in a spiral shape by the stepped surface forming roller 74. This reduces the difference in the degree of plastic deformation between each point on the other end of the preform 10 compared to when the preform 10 is expanded in a linear shape from the other end to one end. Because the difference in the degree is reduced, the possibility of distortion due to the difference in the degree occurring in the preform 10 is reduced. In particular, the possibility of cracks occurring is reduced when the material of the cylinder 12 is austenitic stainless steel.

[0050] The embodiments disclosed herein are illustrative in all respects. The scope of the present invention is not limited to the above-described embodiments. Of course, various design changes may be made without departing from the spirit of the present invention.

[0051] For example, the cylindrical body 12 does not have to have a bottom 24. The length of the cylindrical body 12 from one end to the other end is not particularly limited.

[0052] Furthermore, in the small outer diameter section forming step S322, the preform 10 does not have to rotate on its axis. Therefore, the stepped surface forming roller 74 may proceed linearly from the other end to one end of the preform 10. When the stepped surface forming roller 74 proceeds linearly, the other end of the preform 10 is pushed out linearly.

[0053] In the tooth forming step S302, the location where the gear teeth are actually formed in the tooth forming section 30 is not particularly limited, and the means for forming the teeth is not particularly limited either.

[0054] In the step forming step S324, the surface formed in the step section 112 is not limited to a tapered surface. For example, the surface may be a curved surface that narrows as it approaches the other end of the cylinder 12. [Explanation of symbols]

[0055] 10…Materials 12...Cylinder 20...Aperture forming part 22...Torso 24...Bottom 30…Tooth formation section 32…Section where outer diameter is planned to be reduced 50…Outer diameter reduction processing equipment 70…Mandrel 72...Formed material pressing member 74...Step surface forming roller 76...Pressing member holder 78...Step surface forming roller holder 80...Base of holder for reduction processing 82,164…Coil spring 90...Roller tapered surface 110...Small outer diameter section 112...Step section 130…External tooth preparation device 150…Pedestal 152...Cylindrical body holding member 154...Tooth forming member 156...Anti-sway member 158...Expanding roller

Claims

1. A cylinder forming process in which a metal plate is subjected to plastic working to form a cylinder; a tooth forming step of forming gear teeth by plastic processing on a tooth forming section, which is a section disposed at one end of the cylindrical body, In the cylindrical body forming step, the cylindrical body is formed so as to be divided into the tooth forming section, a small outer diameter section which is disposed on the other end side of the cylindrical body from the tooth forming section and has an outer diameter smaller than that of the tooth forming section, and a step section which is disposed between the tooth forming section and the small outer diameter section and serves as a step between the tooth forming section and the small outer diameter section, In the tooth forming step, the tooth forming section is subjected to plastic working in a state in which the step section is supported and a portion of the cylindrical body on the other end side of the cylindrical body beyond the step section is suspended in air, The cylindrical body forming step includes: a blank forming step in which a cylindrical blank is formed by plastic working the metal plate; a small outer diameter section forming step of forming the small outer diameter section by subjecting the other end of the preform to plastic working so that the outer diameter of the other end of the preform is reduced compared to the outer diameter of the one end of the preform; A step forming step in which the step section is formed, A method for forming a toothed cylindrical body, characterized in that in the step forming process, a step surface forming roller forms a step surface in the step section by pressing and smoothing the area between the tooth forming section and the small outer diameter section.

2. the step surface forming roller is rotatable about an axis extending in a direction from the other end of the base material to the one end of the base material, 2. The method for forming a cylindrical body with teeth according to claim 1, wherein in the step forming step, the base material rotates about an axis parallel to a rotation axis of the step surface forming roller.

3. The method for forming a toothed cylindrical body as described in claim 2, characterized in that in the small outer diameter section forming process, the step surface forming roller is pressed against the outer periphery of the other end of the base material while moving in a direction from the other end of the base material to one end of the base material, and the base material rotates about an axis along the rotation axis of the step surface forming roller, thereby subjecting the other end of the base material to plastic processing.

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