JPH05337587A - Method and apparatus for forging stepped tube - Google Patents

Abstract

PURPOSE:To improve the precision and to shorten the process at the time of forging a stepped tube consisted by connecting a large diameter cylindrical part with the rear end of a small diameter cylindrical part in the same axis. CONSTITUTION:In this apparatus, a fixed die 8 providing an outer forming hole 19, a mandrel 11 consisted by connecting a guide part 11b with tip end side of an expanding diameter part 11a in the same axis and a tube stock 5 having the inner and the outer diameters corresponding to the inner and the outer diameters of the small diameter cylindrical part are prepared. Then, a first step for inserting the tip end part of the tube stock 5 into the small diameter forming hole 17 of the outer forming hole 19 and also regulating the axial directional position of the tube stock 5, a second step for inserting the guide part 11b in the mandrel 11 into the tube stock 5 from the rear side thereof, a third step for expanding the diameter to the rear end part of the tube stock 5 in the condition of regulating the axial directional position by the diameter expanding part 11a in the mandrel 11 and a fourth step for pushing the tube stock 5 into the outer forming hole 19 in the condition of inserting the mandrel 11 are executed in order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepped pipe forging method and apparatus for forging a stepped pipe in which a large diameter cylindrical portion is coaxially connected to a rear end of a small diameter cylindrical portion.

[0002]

2. Description of the Related Art Conventionally, when forging such a stepped pipe, a rod-shaped heating billet positioned in a die is formed by pushing a punch from the rear side thereof, or
The hollow shaft is pushed into the die by applying a pressing force from one side in the axial direction to draw the hollow shaft.

[0003]

However, in the case where the punched pipe is pressed into the heating billet to obtain the stepped pipe, the extraneous part remains in the stepped pipe after forging and is not completely hollow. Is required, and since the billet is heavy, the load on the worker who sets the billet on the die is heavy. Also, in the case where the hollow shaft is pushed into the die, the load on the worker for setting is reduced, but since the shaft is relatively long, when the pressing force acts from one side in the axial direction, uneven thickness and Bending is likely to occur, and the shut height of the forging device becomes relatively large, so that the size of the device is inevitable.

The present invention has been made in view of the above circumstances, and it is possible to forge a stepped pipe with high precision and a reduced number of steps, and forge the stepped pipe that enables downsizing of the apparatus. It is an object to provide a method and a device.

[0005]

In order to achieve the above object, in the forging method according to the first aspect, a large diameter cylindrical portion is formed at the outer end of a small diameter forming hole having an inner diameter corresponding to the outer diameter of the small diameter cylindrical portion. A fixed die having an outer shape forming hole formed by coaxially arranging large diameter forming holes having an inner diameter corresponding to the outer diameter, and a tip end side of an enlarged diameter portion having an outer diameter corresponding to the inner diameter of the large diameter cylindrical portion. A mandrel formed by coaxially connecting guide portions having an outer diameter corresponding to the inner diameter of the small-diameter cylindrical portion, and a pipe material having an inner diameter and an outer diameter corresponding to the outer diameter of the small-diameter cylindrical portion are prepared. A first step of inserting the tip of the material into the small-diameter forming hole of the die and limiting the axial position of the pipe material at a position where the rear end of the pipe material protrudes rearward from the rear end of the large-diameter forming hole; From the rear side of the pipe material whose axial position is regulated Second inserting the guide portion of the Ndoreru
A step, and a third step of expanding the rear end portion of the pipe material by pushing the expanded diameter portion of the mandrel into the rear end portion of the pipe material whose axial position is restricted; The fourth step of releasing the axial movement restriction of the pipe material and pushing the pipe material into the outer shape forming hole while the mandrel is inserted is sequentially executed.

Further, in the forging method according to claim 2, in addition to the structure according to claim 1, the stepped pipe is provided with a groove portion extending in the axial direction on the tip side of the small diameter cylindrical portion,
The axial movement of the pipe material is regulated from the first step to the third step by bringing a groove forming projection provided in the middle of the small diameter forming hole for forming the groove portion into contact with the tip of the pipe material. In the fourth step, the groove portion is formed by the groove forming projection when the pipe material is pushed into the outer shape forming hole.

Further, in the forging device according to the third aspect, a large diameter forming hole having an inner diameter corresponding to the outer diameter of the large diameter cylindrical portion is provided at the outer end of the small diameter forming hole having the inner diameter corresponding to the outer diameter of the small diameter cylindrical portion. A die fixed to a fixed base with an external forming hole formed by being coaxially connected, a movable base that can be moved toward and away from the die along the axial direction of the external forming hole, and a small-diameter cylindrical portion. A cylindrical punch that can be brought into contact with the rear end of a pipe material having an inner diameter and an outer diameter that corresponds to the inner diameter and the outer diameter, and an expansion diameter that has an outer diameter that corresponds to the inner diameter of the large diameter cylindrical portion. A guide portion having an outer diameter corresponding to the inner diameter of the small-diameter cylindrical portion is coaxially provided on the tip side of the diameter portion, and a mandrel fitted to the punch for relative movement in the axial direction and the mandrel in the axial direction. Drive that is connected to the mandrel to drive the Means for contacting the tip of the pipe material inserted into the outer shape forming hole of the die to regulate the axial position of the pipe material, and the axial direction when the pressing force acts on the pipe material from the punch. And a restriction means provided on the die side so that the position restriction can be released.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 11 show an embodiment of the present invention. FIG. 1 is a vertical sectional view of a stepped pipe, and FIG. 2 is a vertical sectional view of a stator shaft formed by using the stepped pipe. FIG. 3 is a vertical cross-sectional side view of the forging device in the state of the first step, FIG. 4 is a simplified diagram showing the configuration of the pump in a state where the movable table is at the upper limit position, and FIG. 5 is immediately after the descent from the upper limit position of the movable table. Schematic view showing the operating state of the pump in the state of FIG.
Is a simplified diagram showing the operating state of the pump while the movable table is being lowered, FIG. 7 is a vertical sectional side view of the forging device in the state of the second step, and FIG. 8 is a vertical sectional side view of the forging device in the state of the third step. 9, FIG. 9 is a vertical sectional side view of the forging device in the state of the fourth step, FIG. 10 is a simplified diagram showing an operating state of the pump in a state where the movable table is at the lower limit position, and FIG. 11 is an elevation of the movable table from the lower limit position. It is a simplified diagram showing the operating state of the pump immediately after the start.

First, in FIG. 1, a stepped pipe 1 is formed by coaxially connecting a large diameter cylindrical portion 1b to a rear end of a small diameter cylindrical portion 1a. A serration groove 2 is engraved on the tip side as a groove portion extending in the axial direction.

This stepped pipe 1 is used, for example, as a material for a stator shaft 3 for a torque converter shown in FIG. 2, and has a serration groove 2 on the outer surface on the tip side.
The stator shaft 3 having the
It is formed by processing the outer surface, and the base end of the lever 4 is welded to the stator shaft 3 near the rear end.

In FIG. 3, when the stepped pipe 1 is forged, the small-diameter cylindrical portion 1 of the stepped pipe 1 is forged.
Pipe material 5 having inner and outer diameters corresponding to the inner and outer diameters of a
Is prepared, and the stepped pipe 1 is formed by forging the pipe material 5 with the forging device 6.

The forging device 6 includes a die 8 fixed on a fixed base 7, a movable base 9 which is connected to a ram (not shown) and can be moved up and down above the die 8, and a punch fixed on the movable base 9. 10, a mandrel 11 fitted to the punch 10 so as to be capable of relative movement in the axial direction, and a double action as a driving means connected to the mandrel 11 for driving the mandrel 11 in the axial direction and provided on the movable base 9. A cylinder 12 and a pump 13 provided between the movable table 9 and the base 7 are provided.

The lower end of the die 8 is fitted into a fitting recess 14 provided on the upper surface of the base 7. Moreover, the lower end of the die 8 is provided with a locking brim portion 8a that projects outward, and the pressing plate 15 that is locked to the locking brim portion 8a is fastened to the base 7 by a plurality of bolts 16. To be done. The die 8 is provided with a contour forming hole 19 extending in the vertical direction corresponding to the contour of the stepped pipe 1.
Is a large-diameter forming hole 18 having an inner diameter corresponding to the outer diameter of the large-diameter cylindrical portion 1b at the outer end, that is, the upper end of the small-diameter forming hole 17 having an inner diameter corresponding to the outer diameter of the small-diameter cylindrical portion 1a in the stepped pipe 1. Are coaxially connected in series. on the other hand,
In the base 7, a large diameter hole 20 having the same inner diameter as the small diameter molding hole 17 and coaxially connected to the small diameter molding hole 17, and a small diameter hole 21 having a smaller diameter than the large diameter hole 20 are coaxially arranged through a step. It will be serialized. A knockout pin 22 is vertically movably inserted in the small-diameter hole 21, and a diameter-expanding head 22a that is vertically movable in the small-diameter forming hole 17 and the large-diameter hole 20 has a tip end of the knockout pin 22. That is, it is provided at the upper end.

By the way, the stepped pipe 1 is provided with a serration groove 2 extending in the axial direction on the tip side of the small diameter cylindrical portion 1a, and is regulated in order to form the serration groove 2 at the same time when the stepped pipe 1 is forged. A large number of groove forming projections 23 are provided on the inner surface of the small diameter forming hole 17 at intervals in the circumferential direction. This groove forming projection 23 is
It is possible to contact the tip of the pipe material 5 inserted into the outer shape forming hole 19 to restrict the axial movement of the pipe material 5, and the pipe material 5 is pushed into the outer shape forming hole 19 with a large pressing force. When the pipe material 5 is wrapped, the serration groove 2 can be formed on the distal end side of the small diameter cylindrical portion 1a by allowing the pipe material 5 to move in the outer shape forming hole 19 in the axial direction.

A holder 25 is fixed to the lower surface of the movable table 9 so as to correspond to the die 8. This holder 25 has a through hole 26 in the center portion and an inner flange portion 27 that extends radially inward at the lower end and an outer flange portion 28 that extends radially outward.
Is formed in a cylindrical shape having a top end. The upper end portion of the holder 25 is fitted into the fitting recess 29 provided on the lower surface of the movable table 9, and the pressing plate 30 locked to the outer flange portion 28 is fastened to the movable table 9 by the plurality of bolts 31. Thus, the holder 25 is fixed to the movable table 9.

The punch 10 has a cylindrical shape and is inserted into the through hole 26 of the holder 25.
At the upper end of 0, a locking collar 10a that engages with the inner collar portion 27 of the holder 25 is provided so as to project outward in the radial direction. Further, the cylinder body 32 of the double-acting cylinder 12 is formed in a bottomed cylindrical shape with the punch 10 side as a closed end, and the open end is oil-tightly closed by a closing member 33 that abuts on the movable table 9. The cylinder body 32 and the closing member 33 are housed in the holder 25 so as to be sandwiched between the upper end of the punch 10 and the lower surface of the movable table 9.

In this way, the punch 10 and the cylinder body 32 are fixed to the movable table 9. In this fixed state, the punch 10 is fixed to the rear end of the pipe blank 5 inserted into the outer shape forming hole 19 of the die 8. The tip of the punch 10 can be brought into contact with and is projected from the holder 25.

In the double-acting cylinder 12, a piston 36 coaxially connected to a rod 35 penetrating the closed end of the cylinder body 32 oil-tightly and slidably forms a piston-side hydraulic chamber 37 between the piston 36 and the closing member 33. In addition, a rod-side hydraulic chamber 38 is formed between the closed end of the cylinder body 32 and the cylinder body 32 so as to be slidably fitted therein. The mandrel 11 slidably fitted to the punch 10 is coaxially and integrally connected to the rod 35. Therefore, when hydraulic pressure acts on the piston side hydraulic chamber 37, the mandrel 11 is driven in a direction to bring its tip closer to the die 8, and when hydraulic pressure acts on the rod side hydraulic chamber 38, the mandrel 11 moves in a direction away from the die 8. Will be done.

The mandrel 11 has a guide portion 11b having an outer diameter corresponding to the inner diameter of the small diameter cylindrical portion 1a on the tip side of the enlarged diameter portion 11a having the outer diameter corresponding to the inner diameter of the large diameter cylindrical portion 1b.
Are formed coaxially in a continuous manner while forming a step, and the expanded diameter portion 11a
A small-diameter shaft portion 11c is coaxially connected to the rear end side with a step, and the shaft portion 11c is coaxially connected to the rod 35. Thus, the length of the rod 35 is set so that substantially the entire length of the mandrel 11 projects from the punch 10 when the piston 36 is at the moving end of the cylinder body 32 toward the closed end.

Referring also to FIG. 4, the pump 13 includes a hydraulic pressure generating cylinder 39 provided on the movable table 9 side and a telescope type cylinder 40 provided on the base 7 side. The hydraulic pressure generating cylinder 39 has a piston 42 slidably fitted in a cylinder body 41 that has an axis line extending vertically and is fixed to the movable base 9, and the upper end of the cylinder body 41 and the piston Between 42, cylinder body 4
1, a first hydraulic pressure generating chamber 43 that generates hydraulic pressure as the piston 42 moves upward is formed.
A second hydraulic pressure generating chamber 44 that generates hydraulic pressure as the piston 42 moves downward with respect to the cylinder body 41 is formed between the lower end of the cylinder 42 and the piston 42. Then cylinder body 4
A first discharge port 45 connected to the first hydraulic pressure generating chamber 43 is provided at the upper end of the first hydraulic pressure generating chamber 43, and the first discharge port 45 is connected to the piston side hydraulic chamber 37 of the double acting cylinder 12. Cylinder body 4
A second discharge port 46 connected to the second hydraulic pressure generation chamber 44 is provided at the lower end of the first hydraulic pressure generation chamber 44, and the second discharge port 46 is connected to the rod side hydraulic chamber 38 of the double acting cylinder 12. Therefore, in the hydraulic pressure generating cylinder 39, the piston 42 is
When moving upward, the double-acting cylinder 12 causes the mandrel 11 to approach the die 8 by the hydraulic pressure generated in the first hydraulic pressure generating chamber 43 acting on the piston-side hydraulic chamber 37 from the first discharge port 45. When the piston 42 is moved downward with respect to the cylinder body 41 in the hydraulic pressure generating cylinder 39 by operating the hydraulic pressure generating cylinder 39, the hydraulic pressure generated in the second hydraulic pressure generating chamber 44 becomes the second hydraulic pressure.
By acting on the rod-side hydraulic chamber 38 from the discharge port 46, the double-acting cylinder 12 is operated in the direction of separating the mandrel 11 from the die 8.

The telescope type cylinder 40 has a fixed cylinder body 47 which is fixed on the base 7 coaxially with the hydraulic pressure generating cylinder 39, and is formed in a bottomed cylindrical shape with the upper end closed and a piston at the lower end. A movable cylinder body 48 having a portion 49 and penetrating the upper end of the fixed cylinder body 47 in an oil-tight and slidable manner, and a piston portion 51 which can come into contact with the piston portion 49 from above and are movable. A rod 5 that penetrates the upper end of the cylinder body 48 in an oil-tight and slidable manner.
The piston portion 49 is slidably fitted in the fixed cylinder body 47, and the piston portion 51 is slidably fitted in the movable cylinder body 48. Also rod 5
The upper end of 0 penetrates the lower end of the cylinder body 41 in the hydraulic pressure generating cylinder 39 in an oil-tight and slidable manner, and is coaxially connected to the piston 42.

In the telescope type cylinder 40, a first hydraulic chamber 52 is formed between the fixed cylinder body 47 and the movable cylinder body 48 and the piston portions 49, 51 so as to face the lower surfaces of the piston portions 49, 51. , A piston portion 49 between the fixed cylinder body 47 and the movable cylinder body 48.
An annular second hydraulic chamber 53 that faces the upper surface of the piston is formed between the movable cylinder body 48 and the rod 50.
An annular third hydraulic chamber 54 that faces the upper surface of No. 1 is formed.

The first hydraulic chamber 52 is connected to a reservoir 59 via a relief valve 55 that opens when the hydraulic pressure in the first hydraulic chamber 52 exceeds a predetermined value. Check valves 56 that allow only the flow of hydraulic oil to the hydraulic chamber 52 side are connected in parallel. Also, the second and third hydraulic chambers 53, 54 are
4 is connected to a reservoir 59 via a relief valve 57 that opens when the hydraulic pressure exceeds a predetermined value.
A check valve 58 that allows only the flow of the hydraulic oil to the second and third hydraulic chambers 53 and 54 is connected in parallel to the valve 7.

Next, the forging process of the stepped pipe 1 by the forging device 6 will be described in order.

[First step]: As shown in FIGS. 3 and 4, with the movable table 9 raised to the upper limit position, the tip of the pipe material 5 prepared in advance is connected to the small diameter forming hole 17 of the die 8. To insert. Then, the tip of the pipe material 5 is provided in the middle of the small diameter forming hole 17 and the groove forming projection 2 is formed.
When the pipe material 5 comes into contact with the outer shape forming hole 19, the axial position of the pipe material 5 is determined, and the rear end portion of the pipe material 5 projects upward from the rear end of the large diameter forming hole 18, that is, the upper end. ..

At this time, in the hydraulic pressure generating cylinder 39 of the pump 13, the piston 42 is at a position where the volume of the second hydraulic pressure generating chamber 44 is minimized, and in the double-acting cylinder 12, the hydraulic pressure of the rod side hydraulic chamber 38 becomes high. That causes the piston 36 to move upward, and therefore the piston 36
The mandrel 11 connected to is pulled into the punch 10.

When the movable table 9 starts descending from its upper limit position, the relief valve 55 is activated when the hydraulic pressure discharged from the first hydraulic chamber 52 in the telescopic cylinder 40 does not exceed a predetermined value. Since the valve 50 is prevented from being opened, the rod 50 is prevented from descending. Therefore, in the hydraulic pressure generating cylinder 39, the downward movement of the piston 42 is prevented, while the cylinder body 41 is prevented.
As shown in FIG. 5, the first hydraulic pressure generating chamber 4
The volume of 3 decreases, and the hydraulic pressure generated in the first hydraulic pressure generating chamber 43 acts on the piston side hydraulic chamber 37 of the double-acting cylinder 12 from the first discharge port 45. Therefore, the piston 36 descends, and the mandrel 11 projects downward from the punch 10.

[Second Step]: When the movable table 9 is further lowered, as shown in FIG. 6, in the hydraulic pressure generating cylinder 39, the piston 42 is directly pushed downward by the upper end of the cylinder body 41. .. Thus, in the telescope type cylinder 40, the rod 50, that is, the piston portion 51
Operates to reduce the volume of the first hydraulic chamber 52, and the relief valve 55 opens as the hydraulic pressure of the first hydraulic chamber 52 increases, whereby the downward movement of the piston portion 51 is allowed. ..

In this way, the movable table 9 descends while contracting the telescopic cylinder 40, and as shown in FIG. 7, the mandrel 1 in a state of protruding from the punch 10.
The guide portion 11b of No. 1 is inserted into the pipe material 5 inserted into the outer shape forming hole 19 from above.

[Third step]: As the movable table 9 is further lowered, the expanded diameter portion 11a of the mandrel 11 is pushed into the rear end of the pipe material 5 as shown in FIG. Will be expanded.

At this time, the movement of the pipe material 5 inward in the axial direction is restricted by the tip of the pipe material 5 being in contact with the groove forming projection 23. In addition, the guide portion 11b
Is inserted in the pipe material 5, the pipe material 5 is not bent by the action of the pressing force from the expanded diameter portion 11a.

[Fourth Step]; When the mandrel 11 is pushed into the rear end of the pipe blank 5, as shown in FIG.
As the movable table 9 descends, the tip of the punch 10 comes into contact with the rear end of the pipe material 5, and the pipe material 5 is directly pressed by the punch 10 while the mandrel 11 is inserted, thereby forming a groove. The axial movement restriction by the projecting projection 23 is released, and the projection 23 is pushed into the outer shape forming hole 19. As a result, the serration groove 2 is formed by the groove forming projection 23 at the tip of the pipe material 5, and the rear end of the pipe material 5 is squeezed by the large diameter forming hole 18 of the outer shape forming hole 19. Therefore, the stepped pipe 1 in which the large diameter cylindrical portion 1b is coaxially connected to the rear end of the small diameter cylindrical portion 1a having the serration groove 2 on the tip side is forged.

In this way, the stepped pipe 1 is molded by sequentially passing through the series of first to fourth steps associated with the lowering of the movable table 9, but the pipe material 5 is pushed into the die 8. Since the guide portion 11b of the mandrel 11 is inserted into the small-diameter cylindrical portion 1a when it is wound, it is possible to prevent the small-diameter cylindrical portion 1a from bending and improve the accuracy of the inner and outer diameters. Further, the large-diameter cylindrical portion 1b is expanded by the expanded diameter portion 11a of the mandrel 11, and then the outer shape forming hole 19 is formed.
Since it is squeezed by the large-diameter forming hole 18, it is possible to improve the outer diameter accuracy by eliminating the need for restriking after forging.

When the movable table 9 is lowered to the lower limit position, the telescopic cylinder 40 of the pump 13 is in the most contracted state as shown in FIG. Thus, the second and third hydraulic chambers 53 of the telescopic cylinder 40,
54 is filled with hydraulic oil from a reservoir 59 via a check valve 58 as the volumes of the hydraulic chambers 53, 54 increase as the pistons 49, 51 descend.

[Fifth Step]: After the movable table 9 is lowered to the lower limit position and the stepped pipe 1 is forged, the knockout pin 22 is raised and the movable table 9 is raised. As a result, the stepped pipe 1 after forging
Will be extracted upward from the outer shape forming hole 19 while keeping its upper end in contact with the punch 10. At this time, in the telescope type cylinder 40 of the pump 13, the second
And the relief of the hydraulic pressure in the third hydraulic chambers 53, 54
7 is blocked by the valve closed state. Therefore, in the hydraulic pressure generating cylinder 39, the cylinder body 41 rises together with the movable base 9, while the upward movement of the piston 42 is blocked. Therefore, as shown in FIG. 11, in the hydraulic pressure generating cylinder 39, the piston 42 is connected to the cylinder body 41.
Relative to the second hydraulic pressure generating chamber 44, the hydraulic pressure generated in the second hydraulic pressure generating chamber 44 acts on the rod side hydraulic chamber 38 of the double-acting cylinder 12 from the second discharge port 46. .. As a result, the piston 36 operates to reduce the volume of the piston side hydraulic chamber 37, and the mandrel 11 is drawn into the punch 10. As a result, punch 10 at the upper end.
The mandrel 11 is pulled out from the stepped pipe 1 brought into contact with.

When the movable table 9 further rises, the piston 42 in the hydraulic pressure generating cylinder 39 is directly pushed upward by the lower end of the cylinder body 41, and in the telescope type cylinder 40, the rod 50, that is, the piston portion 51 is moved to the first position. It operates to reduce the volume of the third hydraulic chamber 54, and the relief valve 5 increases as the hydraulic pressure of the second and third hydraulic chambers 53, 54 increases.
By opening 7 the telescope cylinder 40
Extension operation is allowed. When the movable table 9 is raised to the upper limit position, the forging device 6 is in the state shown in FIG. 3 and the pump 13 is in the state shown in FIG.

According to the forging process by the forging device 6, the stepped pipe 1 in which the large-diameter cylindrical portion 1b is coaxially connected to the rear end of the small-diameter cylindrical portion 1a by the lowering of the movable table 9 once, It is possible to accurately forge while preventing the occurrence of bending and uneven thickness. Moreover, when the guide portion 11b of the mandrel 11 is inserted into the pipe material 5 and when the diameter of the pipe material 5 is expanded by the expanded diameter portion 11a of the mandrel 11, the pipe material 5 inside the outer shape forming hole 19 is formed.
Since the axial movement of the above is restricted by the groove forming projection 23 for forming the serration groove 2, a dedicated structure for restricting the axial movement is not required. further,
A pump 13 for driving the mandrel 11 by making the mandrel 11 axially movable relative to the punch 10.
Since the movable base 9 is operated according to the elevation of the movable base 9, even if the upper limit position of the movable base 9 is set to be relatively low when the pipe material 5 is inserted into the outer shape forming hole 19,
It does not hinder the insertion of the forging device 6, and thus contributes to the reduction of the height of the forging device 6 as a whole, and the mandrel 11 can be easily pulled out from the stepped pipe 1 after forging.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various small design changes can be made without departing from the present invention described in the claims. Is possible.

For example, the groove portion provided on the tip side of the small diameter cylindrical portion 1a in the stepped pipe 1 may be a key groove, or a throttle portion may be provided instead of the groove portion.

Further, it is not necessary to provide a groove portion or a narrowed portion on the tip side of the small diameter cylindrical portion 1a. In that case, in the first to third steps, the pipe material 5 is moved in the axial forming hole 19 in the axial direction. Although it is regulated, the die 8 is a regulating means that can release the regulation of the axial movement in the fourth step.
It should be provided on the side.

[0042]

As described above, according to the method of claim 1, an inner diameter corresponding to the outer diameter of the large diameter cylindrical portion is provided at the outer end of the small diameter molding hole having an inner diameter corresponding to the outer diameter of the small diameter cylindrical portion. A fixed die equipped with an outer shape forming hole that is formed by coaxially connecting large diameter forming holes, and an outer diameter corresponding to the inner diameter of the large diameter cylindrical portion. The mandrel formed by coaxially connecting the guide portions having the outer diameter and the pipe material having the inner diameter and the outer diameter corresponding to the outer diameter of the small diameter cylindrical portion are prepared, and the tip end of the pipe material is The first step of inserting into the small-diameter forming hole and regulating the axial position of the pipe material at the position where the rear end portion of the pipe material protrudes rearward from the rear end of the large-diameter forming hole, and the axial position is regulated. Insert the guide part of the mandrel into the pipe material in the state from the rear side. A second step, a third step of expanding the rear end portion of the pipe material by pushing the expanded diameter portion of the mandrel into the rear end portion of the pipe material whose axial position is restricted, and an outer shape forming hole The fourth step of canceling the axial movement restriction of the pipe material inside and pushing the pipe material into the outer shape forming hole while the mandrel is inserted is sequentially executed. With the series of steps, it is possible to forge the stepped pipe with high accuracy while preventing the occurrence of bending and uneven thickness.

According to a second aspect of the present invention, the stepped pipe is provided with a groove portion extending in the axial direction on the tip side of the small diameter cylindrical portion, and the small diameter forming hole is formed in the middle of the small diameter forming hole for forming the groove portion. By abutting the provided groove forming projection on the tip of the pipe material, the axial movement of the pipe material is restricted from the first step to the third step, and the pipe material is inserted into the outer shape forming hole in the fourth step. Since the groove is formed by the groove-forming projection when it is pushed in, it is not necessary to provide a dedicated restricting means for restricting the axial movement of the pipe material.

According to a third aspect of the present invention, a large diameter forming hole having an inner diameter corresponding to the outer diameter of the large diameter cylindrical portion is coaxially provided at the outer end of the small diameter forming hole having the inner diameter corresponding to the outer diameter of the small diameter cylindrical portion. Among the small-diameter cylindrical portion, a die fixed to a fixed base with an external forming hole formed continuously, a movable table that can be moved toward and away from the die along the axial direction of the external forming hole, A cylindrical punch that can contact the rear end of the pipe material having an inner diameter and an outer diameter corresponding to the outer diameter and is fixed to the movable base, and an enlarged diameter portion having an outer diameter corresponding to the inner diameter of the large diameter cylindrical portion. A guide part having an outer diameter corresponding to the inner diameter of the small-diameter cylindrical part is coaxially connected to the tip side of the mandrel, and the mandrel fitted in the punch is axially movable, and the mandrel is driven in the axial direction. Drive means connected to the mandrel so as to be provided on the movable table, (A) The axial position of the pipe material can be regulated by contacting the tip of the pipe material inserted into the outer shape forming hole of (a) and the axial position regulation can be performed when a pressing force acts on the pipe material from the punch. Since it includes a restriction means provided on the die side so as to be releasable, it is possible to appropriately carry out the forging method described in claim 1 while reducing the size of the forging device.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a stepped pipe.

FIG. 2 is a vertical sectional view of a stator shaft formed by using a stepped pipe.

FIG. 3 is a vertical sectional side view of the forging device in a state of a first step.

FIG. 4 is a simplified diagram showing the configuration of a pump with the movable table in the upper limit position.

FIG. 5 is a simplified diagram showing an operating state of the pump immediately after the movable base starts to descend from the upper limit position.

FIG. 6 is a schematic view showing an operating state of the pump while the movable table is being lowered.

FIG. 7 is a vertical cross-sectional side view of the forging device in the state of the second step.

FIG. 8 is a vertical sectional side view of the forging device in a state of a third step.

FIG. 9 is a vertical sectional side view of the forging device in a state of a fourth step.

FIG. 10 is a simplified diagram showing an operating state of the pump with the movable table in the lower limit position.

FIG. 11 is a simplified diagram showing an operating state of the pump immediately after the movable table starts to be lifted from the lower limit position.

[Explanation of symbols]

 1 Stepped Pipe 1a Small Diameter Cylindrical Part 1b Large Diameter Cylindrical Part 2 Serration Groove as Groove 5 Pipe Material 6 Forging Device 7 Base 8 Die 9 Moveable Base 10 Punch 11 Mandrel 11a Expanding Part 11b Guide Part 12 Double Action as Driving Means Cylinder 17 Small-diameter forming hole 18 Large-diameter forming hole 19 Outer-shape forming hole 23 Groove forming protrusion as regulating means

Claims (3)

[Claims] 1. A stepped pipe forging method for forging a stepped pipe (1) comprising a large diameter cylindrical portion (1b) coaxially connected to a rear end of a small diameter cylindrical portion (1a), comprising: A large diameter forming hole (18) having an inner diameter corresponding to the outer diameter of the large diameter cylindrical portion (1b) is coaxially provided at the outer end of the small diameter forming hole (17) having an inner diameter corresponding to the outer diameter of the cylindrical portion (1a). A fixed die (8) having a contour forming hole (19) formed in a row;
A guide portion (11b) having an outer diameter corresponding to the inner diameter of the small diameter cylindrical portion (1a) is coaxially connected to the tip end side of the enlarged diameter portion (11a) having an outer diameter corresponding to the inner diameter of the large diameter cylindrical portion (1b). A pipe material (5) having an inner diameter and an outer diameter corresponding to the inner diameter and the outer diameter of the mandrel (11) and the small-diameter cylindrical portion (1a) that are provided.
And the front end of the pipe blank (5) is inserted into the small diameter forming hole (17) of the die (8), and the axial position of the pipe blank (5) is adjusted so that the rear end of the pipe blank (5) is The first step of regulating the rear end of the large-diameter forming hole (18) at a position protruding rearward, and the mandrel (1) from the rear side of the pipe material (5) whose axial position is regulated.
A second step of inserting the guide portion (11b) of 1),
First, the diameter of the rear end portion of the pipe material (5) is expanded by pushing the enlarged diameter portion (11a) of the mandrel (11) into the rear end portion of the pipe material (5) whose axial position is restricted. Three
The pipe material (5) is released by releasing the axial movement restriction of the pipe material (5) in the step and the outer shape forming hole (19).
A step of forging a stepped pipe, which comprises sequentially performing a fourth step of pushing into the outer shape forming hole (19) with the mandrel (11) inserted. 2. The stepped pipe (1) is provided with a groove portion (2) extending in the axial direction on the tip side of a small diameter cylindrical portion (1a), and a small diameter forming hole for forming the groove portion (2). The groove forming projection (23) provided in the middle of (17) is brought into contact with the tip of the pipe material (5) to move the pipe material (5) in the axial direction from the first step to the third step. The groove part (2) is formed by the groove forming protrusion (23) when the pipe material (5) is regulated and is pushed into the outer shape forming hole (19) in the fourth step. How to forge stepped pipes. 3. A stepped pipe forging device for forging a stepped pipe (1) comprising a large diameter cylindrical portion (1b) coaxially connected to a rear end of a small diameter cylindrical portion (1a). A large diameter forming hole (18) having an inner diameter corresponding to the outer diameter of the large diameter cylindrical portion (1b) is coaxially provided at the outer end of the small diameter forming hole (17) having an inner diameter corresponding to the outer diameter of the cylindrical portion (1a). A die (8) fixed to a fixed base (7) having a series of external forming holes (19) and a die (8) along the axial direction of the external forming holes (19). The movable base (9) that can approach and separate, and the movable base (9) that can be brought into contact with the rear end of the pipe material (5) having an inner diameter and an outer diameter corresponding to the outer diameter of the small-diameter cylindrical portion (1a). ) Fixed cylindrical punch (10)
And a guide portion (11b) having an outer diameter corresponding to the inner diameter of the small diameter cylindrical portion (1a) is coaxial with the tip of the enlarged diameter portion (11a) having the outer diameter corresponding to the inner diameter of the large diameter cylindrical portion (1b). A mandrel (11) which is connected to the punch (10) and is axially movable, and is connected to the mandrel (11) to drive the mandrel (11) in the axial direction. The driving means (12) provided on the movable table (9) and the tip of the pipe material (5) inserted into the outer shape forming hole (19) of the die (8) are brought into contact with each other to contact the pipe material (5). A restriction means (23) provided on the die (8) side so that the axial position can be regulated and the axial position regulation can be released when a pressing force acts on the pipe material (5) from the punch (10). Stepped pad characterized by including Forging device of flops.