JP5713982B2 - Method for forming hollow portion in shaft portion - Google Patents

Description

  The present invention relates to a method for forming a hollow portion by extrusion in a shaft portion having a flange portion extending radially outward at a midway position in the longitudinal direction.

The pulley of the belt-type continuously variable transmission includes a fixed conical plate and a movable conical plate that forms a V-groove between the fixed conical plate, and the movable conical plate moves forward and backward in the direction of the rotation axis. Thus, the groove width of the V-groove changes.
In the fixed conical plate, the flange-shaped sheave portion extends radially outward from the outer periphery of the shaft portion extending in the rotation axis direction, and an oil hole is formed in the shaft portion along the rotation axis direction.

  Conventionally, this oil hole has been formed by cutting using a drill or the like. However, if the inner diameter of the oil hole is increased in response to the demand for weight reduction of the continuously variable transmission, the cutting area increases, resulting in an increase in work cost. However, there are problems such as an increase in the amount of material to be cut and a decrease in yield due to an increase in the amount of material to be cut.

  Therefore, in order to solve these problems, a method has been proposed in which the oil hole of the shaft portion is formed by backward extrusion that plastically deforms the material (for example, Patent Document 1).

JP 2003-343672 A

  Patent Document 1 discloses a method in which a punch is formed from one end and the other end in the longitudinal direction of the shaft portion to form a hollow portion in the shaft portion.

In the case of such a method, the hollow portion is formed while pushing the surplus pushed by the punch to the opposite side (rear side) to the moving direction of the punch, so the hollow portion is formed so as to cross the inner diameter side of the sheave portion. If so, the shape of the sheave portion changes due to the surplus extruded.
Therefore, it is necessary to restrain the sheave portion from one end and the other end side of the shaft portion to prevent the sheave portion from being deformed. For this reason, there is a problem that the configuration of the forging device is increased in size.

  Therefore, in forming a hollow portion by extrusion molding in a shaft portion having a flange portion in the middle in the longitudinal direction, the hollow portion can be formed so as to cross the inner diameter side of the flange portion without deforming the flange portion. Therefore, a method that can be performed more simply is required.

According to the present invention, a hollow portion extending from one end of the shaft portion to the other end side beyond the inner diameter side of the flange portion is formed in a shaft portion having a flange portion extending radially outward at an intermediate position in the longitudinal direction. In the shaft portion, a reduced diameter portion is provided on the other end side of the flange portion, and the outer diameter of the shaft portion decreases as the distance from the flange portion increases. However, until reaching the inner diameter side of the flange part, the hollow part is formed by forward extrusion, and after reaching the inner diameter side of the flange part, the hollow part is formed by rearward extrusion process, and the tip of the punch is the reduced diameter part. When the boundary is reached, the formation of the hollow part is switched from the rear extrusion process to the front extrusion process, and the hollow part extending to the other end side is formed across the inner diameter side of the reduced diameter part to the other end side. Features It was the method of forming the hollow portion of the shaft portion.

According to the present invention, until the tip of the punch reaches the inner diameter side of the flange portion, the hollow portion is formed while pushing the surplus material pushed by the punch forward, and after reaching the inner diameter side of the flange, the surplus A hollow portion is formed while pushing the meat backward.
Therefore, until the tip of the punch reaches the inner diameter side of the flange part, the surplus part does not move to the side or rear side, so the surplus part moves to the flange part side and the shape of the flange part changes greatly. There is no.
In addition, after the punch tip reaches the inner diameter side of the flange part, if the excess part continues to be pushed forward, the flange part side meat is pulled forward and the base of the flange part is broken. However, when the tip of the punch reaches the inner diameter side of the flange, the surplus wall is pushed backward, so the meat on the flange side is pulled forward and the base of the flange is No breakage or the like occurs.
Therefore, a hollow portion extending from one end of the shaft portion to the other end side beyond the inner diameter side of the flange portion can be formed in the shaft portion without greatly impairing the shape of the flange portion.

It is a flowchart of the formation method of the hollow part concerning embodiment. It is a figure explaining the formation method of the hollow part concerning embodiment. It is a figure explaining the formation method of the hollow part concerning embodiment. It is a figure explaining the formation method of the hollow part concerning embodiment. It is a figure explaining the formation method of the hollow part concerning embodiment.

Hereinafter, a method for forming a hollow portion according to the present invention will be described by taking as an example a case where a hollow portion is formed in a shaft portion of a movable conical plate constituting a pulley of an automatic transmission.
FIG. 1 is a flowchart of a method for forming a hollow portion according to an embodiment.
2A and 2B are diagrams for explaining a method for forming a hollow portion according to the embodiment, in which FIG. 2A is a diagram illustrating a state in which a workpiece W1 having an initial shape is placed on a die 50, and FIG. It is a figure which shows the formation process of the hollow part 12 by front extrusion.
In the following, when explaining the movement direction of the surplus workpiece of the workpiece pressed by the punch P, the movement direction side (lower side in the figure) of the punch P is the front side, and the opposite side to the movement direction (upper side in the figure). ) Is also labeled backward.

As shown in FIG. 2, in the method for forming a hollow portion according to the embodiment, a workpiece W <b> 1 in which a flange-like sheave portion 15 extending radially outward is formed at an intermediate position in the longitudinal direction of a cylindrical shaft portion 11. On the other hand, the hollow part 12 is formed in the shaft part 11 while performing the extrusion process using the cylindrical punch P to adjust the shape of the tip side of the shaft part 11.
Therefore, in forming the hollow portion 12, after applying the lubricant to the surface of the workpiece W1 processed into the initial shape, the workpiece W1 is placed on the die 50 located on the moving direction side (lower side in the drawing) of the punch P. It is set (see FIG. 1: Step S101, (a) of FIG. 2).

Here, the workpiece W1 having an initial shape will be described.
In the workpiece W1, the sheave portion 15 extends from the outer periphery at a position near the one end 11a in the longitudinal direction of the shaft portion 11 in the radial direction of the central axis of the shaft portion 11 (hereinafter referred to as the axis line X). It is formed with the same radial height over the entire circumference of the direction.
The sheave portion 15 has a sheave surface 15a that is inclined at a predetermined angle θ with respect to the axis X on the other end 11b side (lower side in the figure), and the inner diameter side of the sheave portion 15 is thicker than the outer diameter side. The thick portion 15b is formed.

  One end 11a side of the sheave portion 15 of the shaft portion 11 is a base portion 111 in which an insertion hole 12a for the punch P is formed. The insertion hole 12a has an inner diameter that matches the punch P and a cross-sectional shape. From the one end 11a of the base 111, the sheave portion is coaxial with the hollow portion 12 formed in the shaft portion 11. It is formed along the axis X with an axial length L1 extending to the thick portion 15b on the inner diameter side.

  The other end 11b side of the shaft portion 11 than the sheave portion 15 is reduced in diameter in two steps in the direction away from the sheave portion 15, and the cylindrical large diameter portion 112 extending from the inner diameter side of the sheave portion 15 is the sheave portion. It is connected to a cylindrical middle diameter portion 114 via a reduced diameter portion 113 whose outer diameter decreases with distance from 15. A truncated cone-shaped reduced diameter portion 115 having an outer diameter that decreases with distance from the sheave portion 15 is provided at the tip of the medium diameter portion 114.

The die 50 has a hole 51 into which the shaft portion 11 of the workpiece W1 is inserted, and a workpiece support surface 50a that supports the sheave surface 15a side of the sheave portion 15.
Similar to the sheave surface 15a, the work support surface 50a is inclined at a predetermined angle θ with respect to the axis X, and when the work W1 is placed on the die 50, the substantially entire surface of the sheave surface 15a is the work support surface. It is held in contact with 50a.

The hole 51 is provided through the die 50 along the axial direction of the axis X, and has a shape corresponding to the outer diameter of the shaft 11 of the workpiece W4 (see FIG. 5) to be finally formed. doing.
In the embodiment, the diameter of the hole 51 is reduced in three steps in the direction away from the work support surface 50a, and the large diameter hole 511, the reduced diameter hole 512, and the medium diameter are sequentially formed from the work support surface 50a side. A hole 513, a reduced diameter hole 514, and a small diameter hole 515 are formed.

The diameter-reduced hole 512 side (lower side in the figure) of the large-diameter hole 511 is formed in a cylindrical shape having the same inner diameter along the axial direction of the axis X, and the opposite side to the diameter-reduced hole 512 is Corresponding to the shape of the thick portion 15b of the sheave portion 15, the diameter is increased toward the upper side in the figure.
The large-diameter hole portion 511 is connected to the medium-diameter hole portion 513 through the reduced-diameter hole portion 512 that decreases in diameter as it goes downward in the drawing, and the medium-diameter hole portion 513 goes downward in the drawing. It is connected to the small-diameter hole 515 through the reduced-diameter hole 514 that decreases in diameter.

The small diameter hole portion 515 extends along the axis X, and a cylindrical knockout pin 30 is inserted on the lower end side of the small diameter hole portion 515.
An upper end 30a of the knockout pin 30 is provided with an interval Wa between the other end 11b of the shaft portion 11 of the workpiece W1 set on the die 50, and at an initial stage before the extrusion process is started, A space S is secured in the small diameter hole 515.

  Returning to the description of the method of forming the hollow portion 12, when the setting of the workpiece W1 on the die 50 is completed (FIG. 1: step S101), the punch P is inserted and set in the insertion hole 12a of the shaft portion 11, The punch P is moved to the other end 11b side (the lower side in the drawing) of the shaft portion 11, and an extrusion process for plastically deforming the material constituting the workpiece W1 is started.

Here, since the space S is provided between the other end 11b of the workpiece W1 and the knockout pin 30, when the extrusion process is started, the surplus wall of the workpiece W1 pressed by the punch P is the space S. The inside will move downward on the knockout pin 30 side.
Therefore, until the surplus of the workpiece W1 reaches the knockout pin 30 (filled in the space S), the shaft 11 is hollowed by adjusting the shape of the small diameter portion 116 of the shaft 11 by forward extrusion. The portion 12 is formed (see FIG. 1: Step S102, FIG. 2B).

Here, in the embodiment, the insertion hole 12a is formed in the base portion 111 of the shaft portion 11 in advance, and the formation of the hollow portion 12 by extrusion processing is performed from the inner diameter side of the thick portion 15b of the sheave portion 15. It has become.
For example, when the insertion hole 12a is not formed in the base 111 in advance or when the length of the insertion hole 12a in the axis X direction is short, the meat pressed by the punch P in forming the hollow portion 12 is There is a risk that the base 111 will be greatly deformed by moving to. In the embodiment, the insertion hole 12a is formed with a length L1 extending to the inner diameter side of the sheave portion 15 (thick wall portion 15b), so that the meat pressed by the punch P does not move in a large amount in the radial direction. Therefore, the base 111 and its vicinity are not greatly deformed.

  In the following description, the hollow portion formed in the shaft portion 11 by the punch P including the portion of the insertion hole 12a of the punch P is denoted as the hollow portion 12 using the reference numeral 12.

  FIG. 3 is a diagram illustrating a method for forming a hollow portion according to the embodiment, and (a) is a diagram illustrating a state in which the punch P has reached a switching point from a front extrusion process to a rear extrusion process. A workpiece W2 having an intermediate shape obtained by forward extrusion is shown. (B) is a figure which shows the formation process of the hollow part 12 by back extrusion.

When the punch P is pushed further downward from the position shown in FIG. 2B, the movement of the surplus of the workpiece W1 to the front side (downward side) is prevented by the knockout pin 30 (FIG. 1). : Step S103, Yes, see FIG. 3A).
If it does so, the surplus pushed by punch P will move the inside of hole 51 to the back side (upper side), and will be pushed out from large diameter hole 511.
Therefore, at the time shown in FIG. 3A, the extrusion process is switched from the front extrusion process to the rear extrusion process.

  At this time, the basic shape of the large-diameter hole portion 511 has a substantially cylindrical shape, and directivity is given to the movement direction of the extruded surplus. Therefore, the extruded surplus moves to the rear side (upper side) along the axis X while maintaining the cross-sectional shape of the large-diameter hole 511, and the large-diameter portion 112 in the workpiece W2 is the axis of the axis X. It will be stretched in the direction.

  Here, in the embodiment, when the tip of the punch P reaches the intersection of the virtual line Im1 passing through the sheave surface 15a and the axis X, the movement of the surplus of the workpiece W1 to the front side is caused by the knockout pin 30. A distance Wa between the other end 11b of the workpiece W1 in the initial shape and the upper end 30a of the knockout pin 30 is set so as to be prevented (see FIG. 2A).

  For example, even after the intermediate shape workpiece W2 shown in FIG. 3A is obtained, the front end Pa of the punch P is pushed further forward beyond the imaginary line Im1 while being pushed forward, and is indicated by a wavy line in the figure. When reaching the position shown in the figure, in the process, the meat on the side of the thick portion 15b of the sheave portion 15 is drawn to the front side (lower side in the figure) following the movement of the punch P (in the figure, virtual arrow) This is because the base of the sheave portion 15 may be broken or cracked.

Therefore, in the embodiment, when the front end Pa of the punch P reaches the inner diameter side of the sheave portion 15, the front extrusion processing is switched to the rear extrusion processing, and the sheave portion 15 is configured. The meat is prevented from being drawn into the movement direction side of the punch P.
Therefore, while the hollow portion 12 is formed by the backward extrusion with respect to the intermediate-shaped workpiece W2 obtained by the forward extrusion processing, the surplus material pushed by the punch P is extruded to the rear side (in FIG. 3). (B), see arrow), the large diameter portion 112 is extended backward without breaking the shape of the sheave portion 15.

FIG. 4 is a diagram for explaining a method for forming a hollow portion according to the embodiment. FIG. 4A is a diagram for explaining a state in which the punch P has reached a switching point from backward extrusion processing to forward extrusion processing. There is shown a workpiece W3 having an intermediate shape obtained by backward extrusion.
(B) is a figure which shows the state from which the knockout pin 30 was removed from the die | dye for the front extrusion process.

When the formation of the hollow portion 12 by the backward extrusion process is continued from the state shown in FIG. 3B, the tip Pa of the punch P reaches the inner diameter side of the reduced diameter portion 113 (FIG. 1: step). S105, Yes, see FIG. 4A).
Then, at that time, knockout pin 30 is removed (see FIG. 4B). Thereby, since the surplus pushed by the punch P can be moved to the front side (lower side in the figure), the extrusion process is switched from the rear extrusion process to the front extrusion process (FIG. 1: step). S106, see FIGS. 4A and 4B).

For example, even after the intermediate-shaped workpiece W3 shown in FIG. 4A is obtained, the tip Pa of the punch P is pushed below the reduced diameter portion 113 while being pushed backward, and is indicated by a wavy line in the drawing. When reaching the position on the inner diameter side of the medium diameter portion 114 shown, in the process, the meat in the medium diameter portion 114 on the front side of the punch P passes through the gap ΔW (step) with the medium diameter hole portion 513. Thus, it will be drawn back (upper side in the figure) (see the virtual arrow in the figure).
Here, since the medium diameter portion 114 has a smaller diameter than the large diameter portion 112, the amount of meat that can be moved to the rear side is limited to the large diameter portion 112 side. When the meat on the medium diameter portion 114 side is drawn to the large diameter portion 112 side with the movement, there is a risk that cracks may occur in the reduced diameter portion 113 due to the lack of movable meat.

  Therefore, in the embodiment, the knockout pin 30 is at an arbitrary time point (any position within the range indicated by ΔL in the drawing) while the tip Pa of the punch P is positioned on the inner diameter side of the reduced diameter portion 113. Is removed and the meat on the medium diameter part 114 side is pushed to the front side instead of moving the meat on the medium diameter part 114 side to the rear on the large diameter part 112 side by switching from the rear extrusion process to the front extrusion process. In this way, the possibility of cracking is reduced.

  Note that the switching from the backward extrusion process to the forward extrusion process may be performed within the range indicated by ΔL in the drawing of the punch P, but the distal end Pa of the punch P is the large diameter portion 112 of the reduced diameter portion 113. It is preferable to be performed when the base end on the side is reached. This is because the amount of meat that can move to the rear side (upper side in the figure) decreases as it approaches the middle diameter portion 114 side.

  FIG. 5 is a diagram illustrating a method for forming a hollow portion according to the embodiment, and (a) is a diagram illustrating a state in which the punch P has reached a formation end point of the hollow portion 12 by forward extrusion processing. A work W4 having a final shape obtained by forward extrusion is shown. (B) is a figure explaining the removal from the die | dye 50 of the workpiece | work W4 of the last shape.

When the punch P is pushed further downward from the state shown in FIG. 4B, the punch P pushes the surplus portion forward (downward in the figure), and the small diameter portion 116 of the workpiece W4 is moved along the axis X. The hollow portion 12 is formed in the shaft portion 11 while extending in the axial direction.
Then, when the length of the hollow portion 12 formed in the shaft portion 11 reaches a predetermined length (for example, a length indicated by L2 in the drawing) by this forward extrusion processing (FIG. 1: step). S107, Yes, see FIG. 5A), the movement of the punch P in the downward direction in the drawing is finished, and the formation of the hollow portion 12 by the forward extrusion process is finished (FIG. 1: step S108).

  In the embodiment, immediately before the tip Pa of the punch P reaches the inner diameter side of the reduced diameter portion 115, the formation of the hollow portion 12 by the forward extrusion process is finished. This is because if the hollow portion 12 is formed up to the position where the tip Pa of the punch P reaches the inner diameter side of the reduced diameter portion 115, the reduced diameter portion 115 after the hollow portion 12 is formed becomes too thin.

  When the forward extrusion process is completed, as shown in FIG. 5 (b), the punch P is pulled out from the final workpiece W4, and then the knockout pin 30 is inserted into the hole 51 (small-diameter hole 515). The workpiece W4 is removed from the die 50 by pushing up W4.

  As described above, when the hollow portion 12 is formed in the shaft portion 11 by the extrusion processing using the cylindrical punch P, the direction of the sheave portion 15 is changed by appropriately switching the direction in which the surplus material pushed by the punch P is pushed. The hollow portion 12 can be formed so as to cross the inner diameter side of the sheave portion 15 without causing deformation or breaking of the root of the sheave portion 15. Therefore, unlike the case of the forming method according to the conventional example, it is not necessary to restrain the sheave portion 15 from both sides in the axial direction of the axis X, and only the die 50 that restrains one side of the sheave portion 15 may be prepared. The hollow portion can be formed more easily without increasing the size of the forging device.

As described above, in the embodiment, the inner diameter side of the sheave portion 15 is extended from the one end 11a of the shaft portion 11 into the shaft portion 11 having the sheave portion 15 (flange portion) extending radially outward at an intermediate position in the longitudinal direction. A method of forming the hollow portion 12 that extends beyond the other end 11b by extrusion using a columnar punch P,
The hollow portion 12 is formed by forward extrusion until the tip Pa of the punch P reaches the inner diameter side of the sheave portion 15, and after reaching the inner diameter side of the sheave portion 15, the hollow portion 12 is formed by rearward extrusion processing. A method of forming the hollow portion 12 in the shaft portion 11 having the configuration described above was adopted.

If comprised in this way, until the front-end | tip Pa of punch P reaches the inner diameter side of the sheave part 15, the hollow part 12 will be formed, pushing the surplus of the workpiece W1 of an initial shape ahead, and the inner diameter side of the sheave part 15 Then, the hollow portion 12 is formed while pushing the surplus of the intermediate-shaped workpiece W2 backward.
Therefore, until the tip Pa of the punch P reaches the inner diameter side of the sheave portion 15, the surplus does not move radially outward or rearward in the movement direction of the punch P. It does not move and the shape of the sheave portion 15 does not change greatly.
Further, after the leading end Pa of the punch P reaches the inner diameter side of the sheave portion 15, when the surplus meat is continuously pushed forward, the meat on the sheave portion 15 side is drawn forward and the sheave portion 15 is deformed. However, when the tip Pa of the punch P reaches the inner diameter side of the sheave portion 15, the surplus wall is pushed out rearward. Therefore, the flesh on the sheave portion 15 side is drawn forward and the shape of the sheave portion 15 does not change greatly, and the base of the sheave portion 15 does not break or break.
Therefore, the hollow portion 12 extending from the one end 11a of the shaft portion 11 to the other end 11b side beyond the inner diameter side of the sheave portion 15 can be formed in the shaft portion 11 without greatly impairing the shape of the sheave portion 15 and the like.

  In particular, since the hollow portion 12 that becomes the oil passage is formed in the shaft portion 11 by the backward extrusion process that plastically deforms the material, there arises a problem of the processing of the cutting scrap as in the case of forming the hollow portion by the cutting process. Absent. In addition, even when the inner diameter of the hollow portion is increased, there are problems in forming the hollow portion by cutting, that is, the work cost increases, the amount of material discarded increases, and the yield of the material deteriorates. Does not occur.

In the shaft portion 11, a reduced diameter portion 113 is provided closer to the other end 11 b than the sheave portion 15, and the diameter of the shaft portion 11 decreases as the outer diameter of the shaft portion 11 moves away from the sheave portion 15.
When the tip Pa of the punch P reaches the boundary with the reduced diameter portion 113, the formation of the hollow portion 12 in the shaft portion 11 is configured so that the formation of the hollow portion 12 can be switched from the rear extrusion processing to the front extrusion processing. .

Even if the leading edge Pa of the punch P reaches the reduced diameter portion 113, if the rearward extrusion of the surplus is continued, the amount of meat that can be moved from the middle diameter portion 114 side before the reduced diameter portion 113 is increased. Since it decreases, there is a possibility that cracks or the like may occur in the reduced diameter portion 113.
With the configuration as described above, when the tip Pa side of the punch P reaches the reduced diameter portion 113, the meat on the medium diameter portion 114 side is not moved rearward on the large diameter portion 112 side, but the medium diameter portion 114 is moved. By pushing the inner meat forward, the possibility of cracking in the reduced diameter portion 113 can be reduced.

In addition, since the load applied to the punch in the case of the backward extrusion is larger than that in the case of the forward extrusion, when the hollow portion is formed only by the conventional backward extrusion, the length of the hollow portion formed in the shaft portion is If the length is longer, the length of the punch becomes longer, and there is a risk that the punch will break.
In the embodiment, when the hollow portion is formed by the extrusion process using the punch P, the extrusion direction of the surplus material pushed by the punch P is changed in the order of forward extrusion, backward extrusion, and forward extrusion. And the front extrusion are combined to form the hollow portion 12. Therefore, since the load acting on the punch can be reduced throughout the extrusion process, the durability of the punch is improved.

Further, with the initial shape workpiece W1 having the shaft portion 11 and the flange-shaped sheave portion 15 extending radially outward at a midway position in the longitudinal direction of the shaft portion 11, cold using a cylindrical punch P is performed. The hollow portion 12 extending from one end of the shaft portion 11 to the other end side of the sheave portion 15 is formed in the shaft portion 11 while adjusting the shape of the shaft portion 11 by performing extrusion processing by plastic deformation. A method,
(A) The workpiece of the initial shape is formed on a die 50 having a hole portion 51 having a shape corresponding to the shape of the shaft portion 11 of the final-shaped workpiece W4 and a workpiece support surface 50a for supporting the sheave surface 15a of the sheave portion 15. W1 is set, the other end 11b side of the shaft portion 11 is inserted into the hole portion 51, and the sheave surface 15a is supported by the workpiece support surface 50a.
(B) After inserting and setting the punch P in the insertion hole 12a opened in the one end 11a of the shaft portion 11 of the workpiece W1 having the initial shape, the punch P is moved to the other end 11b side of the shaft portion 11,
(A) The tip Pa of the punch P reaches the inner diameter side of the sheave part 15,
(B) Until the movement of the excess wall pushed forward by the punch P is hindered by the knockout pin 30 inserted into the hole 51,
Forming a hollow portion 12 in the shaft portion 11 by a forward extrusion process to obtain a workpiece W2 having an intermediate shape;
(C) In the intermediate-shaped workpiece W2, the punch P is further moved to the other end 11b side of the shaft portion 11, and the tip Pa of the punch P is a boundary with the reduced diameter portion 113 in the shaft portion 11 of the workpiece W2. To form a hollow portion 12 in the shaft portion 11 by backward extrusion until the workpiece W3 has an intermediate shape,
(D) After removing the knockout pin 30 from the hole 51, in the intermediate workpiece W3, the punch P is further moved to the other end 11b side of the shaft portion 11 to perform forward extrusion, Forming a hollow portion 12 in the shaft portion 11 while adjusting the shape of the shaft portion 11 to obtain a workpiece W4 having a final shape.

  With this configuration, when the hollow portion 12 is formed, the meat constituting the sheave portion 15 is not drawn by the punch P moving in the shaft portion 11 and the sheave portion 15 is not deformed. As in the case of the method, it is not necessary to restrain the sheave portion 15 from both sides in the axial direction of the axis X, and only the die 50 that restrains one side of the sheave portion 15 may be prepared. Therefore, the hollow portion can be formed more easily.

  In the embodiment, the case where the hollow portion is formed in the shaft portion of the movable conical plate constituting the pulley of the automatic transmission is illustrated, but the shaft member in which the radially extending flange is provided at the midway position in the longitudinal direction. Furthermore, if the hollow portion is formed so as to cross the inner diameter side of the flange, the method according to the present invention can be suitably applied. Therefore, it can be suitably used not only when the hollow conical plate of the pulley is formed but also when the hollow portion is formed in the shaft portion of a reduction gear or the like.

11 shaft portion 11a one end 11b other end 111 base portion 112 large diameter portion 113 reduced diameter portion 114 medium diameter portion 115 reduced diameter portion 116 small diameter portion 12 hollow portion 12a insertion hole 15 sheave portion 15a sheave surface 15b thick portion 30 knockout pin 30a upper end 50 Dies 50a Workpiece Support Surface 51 Hole 511 Large Diameter Hole 512 Reduced Diameter Hole 513 Medium Diameter Hole 514 Reduced Diameter Hole 515 Small Diameter Hole Im1 Virtual Line P Punch Pa Tip S Space W1 Work W2 Work W3 Work W4 Work Wa interval X axis

Claims (2)

A hollow portion extending from one end of the shaft portion to the other end side beyond the inner diameter side of the flange portion is extruded using a columnar punch into a shaft portion having a flange portion extending radially outward at an intermediate position in the longitudinal direction. A method of forming by processing,
In the shaft portion, a reduced diameter portion is provided on the other end side of the flange portion, and the diameter of the shaft portion decreases as the outer diameter of the shaft portion increases.
Tip of the punch until it reaches the inner diameter side of the flange portion, forming said hollow portion by the forward extrusion, after reaching the radially inner side of the flange portion, the hollow portion is formed by backward extrusion process ,
When the tip of the punch reaches the boundary with the reduced diameter portion, the formation of the hollow portion is switched from the rear extrusion processing to the front extrusion processing, and the inner diameter side of the reduced diameter portion is changed to the other end side. A method for forming a hollow portion in a shaft portion, comprising forming the hollow portion extending across to the other end side . A flange portion that has a reduced diameter portion whose outer shape becomes smaller from one end side to the other end side of the shaft portion at a midway position in the longitudinal direction of the shaft portion, and that extends radially outward to the one end side of the reduced diameter portion The workpiece having the initial shape is subjected to extrusion using a columnar punch, and the other end of the shaft portion extends from the one end to the inner diameter side of the flange portion and the inner diameter side of the reduced diameter portion. A method for forming a hollow portion in a shaft portion that forms a hollow portion extending to an end side,
The initial shape workpiece is set in a die having a shape corresponding to the outer shape of the shaft portion of the final shape workpiece and the support surface of the flange portion, and the other end side of the shaft portion is placed in the hole portion. And supporting the flange portion on the support surface;
The punch was moved from one end to the other end side in the shaft portion of the workpiece of the initial shape, and the tip of the punch reached the inner diameter side of the flange portion and was pushed out to the other end side by the punch. Forming a hollow portion in the shaft portion by a forward extrusion process until the movement of the surplus wall is hindered by a knockout pin inserted into the hole portion, and forming a first intermediate shape workpiece;
In the first intermediate shape workpiece, the punch is further moved to the other end side of the shaft portion, and the tip of the punch is at the boundary with the reduced diameter portion of the shaft portion of the first intermediate shape workpiece. Forming a hollow portion in the shaft portion by backward extrusion until reaching a second intermediate shape workpiece;
After the knockout pin is removed from the hole, the punch is further moved to the other end side of the shaft portion in the second intermediate-shaped workpiece to perform forward extrusion, thereby forming the shape of the shaft portion. forming the hollow portion to the shaft portion while established a method of forming the hollow portion of the shaft portion you, comprising the steps, a to the final shape the workpiece.

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