JPH091274A - Closed forging mold structure - Google Patents

Abstract

(57) [Summary] [Purpose] The press ram drives a container or mandrel to generate a relative speed difference between the rough material and the container, thereby enhancing the fill-up property. [Structure] At the time of forging, one or both of the mandrels 18 and 38 and the container 20 are driven by the upper press ram 11.
There is a relative velocity difference between the material that has undergone plastic flow of No. 2 and the inner surface of the container 20 with which this material is in contact. Therefore, the material in contact with the inner surface of the container 20 is
It is drawn in the moving direction of the container 20 by the frictional force,
The material is promoted to flow into a corner or the like where the material in the mold is difficult to be filled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a mold used for closed forging.

[0002]

2. Description of the Related Art The structure of a conventional general closed forging die is shown in FIG.
It is shown in In this mold structure, a cylindrical punch 2 and a mandrel 3 are arranged on the same axis inside a cylindrical container 1 with their end faces facing each other. Further, a cylindrical forged rough material 4 is loaded in a portion of the container 1 which is closed by the punch 2 and the mandrel 3 (see the left half portion of FIG. 5).

In this conventional closed forging die, when the punch 2 presses the forging raw material 4 and presses it against the mandrel 3, the forging raw material 4 causes plastic flow and the container 1
Flows into the free surface portion (in-mold space) between the punch 2 and the outer peripheral surface of the mandrel 3 (see the right half portion of FIG. 5).

At this time, the punch surface pressure sharply increases at the start of processing and then gradually decreases due to the inflow of material,
The material re-rises from the point of contact with the inner surface of the container 1. Then, the contact rate of the material with the inner surface of the container 1 is 85
%, The punch surface pressure rises sharply. This is because the material gradually fills the mold, the free surface portion decreases, and the deformation constraint increases. At this time, container 1
It is considered that the contact portion between the inner surface of and the material is approximately in the hydrostatic compression state, and the compression hydrostatic pressure rapidly increases. In this state, in order to completely fill (fill up) the material to the corners of the die, a high surface pressure ratio of 7.4 was required for the punch 2.

Therefore, a closed forging die has been proposed in which the material can be completely filled in the die with a relatively low pressure. This is equipped with a mechanism for driving a closed forging die container, and in the latter half of the closed forging process, when the free surface part of the flowing material decreases and the deformation constraint increases, the flow direction of the material changes. The container is driven in parallel directions to reduce the contact resistance between the inner surface of the container and the material.

For example, FIG. 6 shows a closed forging die for processing a columnar rough material 5 into a flanged part, which is a cylindrical shape which is installed on a floor and horizontally provided between opposing frames 6 and 6. Die 7 and a cylindrical container 8 covering the outer periphery of the die 7 so as to close the opening formed in the center in the circumferential direction.
A mandrel 9 that closes one end side (the right end side in the drawing) of the die 7, a punch 10 that strokes on the same axis as the mandrel 9 and presses the rough material 5 with the mandrel 9, It is provided with push rods 8a, 8a for driving the container 8 in a direction parallel to the compression direction of the rough material 5.

When the closed forging process is performed, the rough material 5 is loaded between the mandrel 9 and the punch 10 and then the container 8 is driven by the push rod 8a while the rough material 5 is installed by the punch 10. , Promotes material flow to the free surface. That is, by driving the container 8, the material is drawn in the movement direction of the container 8 by the frictional force of the material in contact with the container 8, and the material flows into the free surface portion to fill up the corner portion. Therefore, by driving the container 8, it is possible to forge with a lower pressure than when the container is fixed.

[0008]

However, in the above-described closed forging die for driving the container, the operation of driving the punch 10 to generate a force to take up most of the deformation of the rough material 5 and the free surface portion. It is necessary to perform two operations, that is, an operation of driving the container 8 at a predetermined timing in order to promote the material flow to the. For this reason, a so-called CNC press machine (Computer Numerical control Press) having two or more controllable multi-axis pressurizers in one equipment must be used. It was a technology that could not be implemented.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a closed forging die structure that can be completely filled with a normal press machine at a relatively low pressure.

[0010]

As a means for solving the above problems, the present invention is provided between a press ram and a reaction force receiving portion facing the press ram, and is attached to the reaction force receiving portion side. And a punch attached to the side of the press ram, reciprocating on the same axis as the mandrel, and pinching and deforming the rough material between the mandrel and the mandrel, and arranged between the punch and the mandrel. In a closed forging die structure including a tubular container provided so as to cover the rough material from the outside, one or both of the mandrel and the container have a displacement amount due to a pressing force of the press ram. It is characterized in that it is held by different holding members so as to be movable in a direction parallel to the moving direction of the punch so that a relative speed difference is generated between the rough material and the container. .

[0011]

As described above, in the closed forging die structure of the present invention, one or both of the mandrel and the container are made of an elastic material such as a coil spring or a urethane spring having different displacements when pressed by the press ram. While being held by a holding member provided with movably in a direction parallel to the moving direction of the punch, either or both of the mandrel and the container during the forging process are driven and displaced by the press ram. Since the relative speed difference is generated between the rough material and the container, the rough material is deformed by being pinched between the punch and the mandrel, and the material causes plastic flow toward the free surface portion. At this time, a relative velocity difference is generated between the material having the plastic flow and the inner surface of the container with which the material is in contact. Therefore, the material in contact with the inner surface of the container is drawn in the moving direction of the container by the frictional force, and the material is promoted to flow into the corners or the like where the material in the mold is difficult to fill.

[0012]

Embodiments of the closed forging die structure of the present invention will be described below with reference to FIGS.

FIG. 1 shows a first embodiment of the closed forging die structure of the present invention. Of the upper and lower press rams 11 and 12 which are arranged to face each other of the press machine, the movable upper press ram 1
1, an upper bolster 13 is provided so as to linearly stroke together with the upper press ram 11, and a lower bolster 1 serving as a reaction force receiving portion is provided on the lower press ram 12 on the fixed side.
4 are provided integrally.

A cylindrical container pushing member 15 is attached to the center of the lower surface of the upper bolster 13, and a cylindrical punch 16 is provided inside the container pushing member 15.
Is fitted so as to be slidable in the vertical direction. Further, the punch 16 has a flange portion 16a at an upper end thereof engaged with an annular rib 15a extending to an inner periphery of a lower portion of the container pushing member 15 to prevent the punch 16 from coming off.

Further, the lower surface of the upper bolster 13 and the punch 16
A cylindrical urethane spring 17 made of urethane rubber as an elastic material is interposed between the upper end surface of the punch 16 and the flange portion 16a of the punch 16 approaches the annular rib 15a by the elastic force of the urethane spring 17. Direction (downward in FIG. 1), the urethane bolster 17 is compressed by being pushed by the descending upper bolster 13 to reduce the descending speed of the punch 16.

Below the punch 16, a cylindrical mandrel 18 having a diameter larger than the outer diameter of the punch 16 is fixedly mounted on the lower bolster 14 so as to be located on the same axis as the punch 16. . Further, on the outer periphery of the upper portion of the punch 16, a ring-shaped die 19 having a thickness that fills the difference in outer diameter between the punch 16 and the mandrel 18 is pushed by the container pushing member 15 and descends. It is provided.

Further, on the outer periphery of the punch 16 and the mandrel 18, there is provided a cylindrical container 20 for closing the outer periphery of the space between the lower ends of the punch 16 and the die 19 and the upper end of the mandrel 18, respectively. A return spring 21 which is a holding member is interposed between the lower bolster 14 and the upper surface of the lower bolster 14, and the die 19 is pushed by the container pushing member 15 together with the container 20. And slide together.

The outer circumference of the container 20 is surrounded by the lower ends of the punch 16 and the die 19 and the upper end of the mandrel 18.
The rough material 22 is loaded into the space surrounded by and closed forging is performed. In FIG. 1, reference numeral 23 is a guide post that guides the up and down movement of the upper bolster 13.

Next, the operation of this embodiment having the above-described structure will be described. The upper press ram 1 with the coarse material 22 loaded in the space between the punch 16 and the mandrel 18.
When 1 is lowered, first, as the upper bolster 13 is lowered, the container 20 is pushed through the container pushing member 15 and is lowered at the speed V1. Then, when the upper bolster 13 further descends and the lower end of the punch 16 comes into contact with the rough material 22 to start pressing, the urethane spring 17 is compressed by the deformation resistance of the rough material 22, and the urethane spring 17 is compressed. The lowering speed is decelerated accordingly, and the punch 16 descends at the speed V2.

At this time, the coarse material 22 clamped between the mandrel 18 and the punch 16 does not move because the mandrel 18 is fixed on the lower bolster 14, and therefore is driven by the upper bolster 13. Container 20 descending
A relative speed difference occurs between the rough material 22 and the rough material 22. As a result, the rough material 22 sandwiched and pressed by the descending punch 16 and the mandrel 18 from the vertical direction flows toward the space below the die 19 on the outer peripheral side where the free surface portion remains, and the rough material 22 of the container 20 is discharged. As the free surface portion decreases due to contact with the inner surface, the resistance increases and it becomes difficult to flow.

However, in this embodiment, since the container 20 descends, the rough material 22 contacting the inner surface of the container 20 is pulled downward by the frictional force with the inner surface (in the direction of arrow Wb in the figure). Flow into the lower corners and the filling of the material in the lower corners is improved.

In this way, the container 2
Since 0 is relatively moved while forging is performed, it is possible to manufacture a good forged product having no thin portion by a relatively low pressure.

Even when the urethane spring 17 is not provided between the upper bolster 13 attached to the upper press ram 11 and the punch 16, the effect of accelerating the fill-up can be obtained.

FIG. 2 shows a second embodiment of the closed forging die structure of the present invention. The same components as those of the first embodiment are designated by the same reference numerals and their detailed description will be given. Will be omitted and will be described below with reference to the drawings.

At the center of the lower surface of the upper bolster 13, a cylindrical punch 26 is mounted vertically with its upper end supported, and a cylindrical container pushing member 25 is concentrically provided on the outer periphery of the punch 26. Installed.

Below the punch 26, a cylindrical mandrel 18 having the same thickness as the punch 26 is provided.
6 is erected on the lower bolster 14 so as to be on the same axis as 6. A cylindrical container 20 that closes the outer circumference of the space between the lower end of the punch 26 and the upper end of the mandrel 18 is provided on the outer circumference of the punch 26 and the mandrel 18.
However, a return spring 21 is interposed between the lower end thereof and the upper surface of the lower bolster 14 so as to be vertically slidable.

A cylindrical urethane spring 27 is sandwiched between the upper end of the container 20 and the lower end of the container pushing member 25. The spring constant of the urethane spring 27 is the return spring. 21
It is set smaller than the spring constant of. Therefore, when lowering the container 20, the urethane spring 27 is first compressed to some extent and then the return spring 2 is pressed.
When 1 is compressed, the timing at which the container 20 starts descending is delayed, and since the urethane spring 27 descends while being compressed, the descending speed of the container 20 is also reduced.

Next, the operation of the second embodiment constructed as described above will be explained. The punch 26 and the mandrel 18 are described below.
The rough material 22 is loaded into the space between and, and the closed forging process is performed. At this time, first, the punch 26 and the container pushing member 25 are driven downward by being driven by the descending upper bolster 13.
Therefore, the punch 26 descends at the speed V2, and the rough material 22 is pressed against the fixed mandrel 18.

On the other hand, when the container pushing member 25 descends, the container 20 is pushed down via the urethane spring 27. However, since the spring constant of the urethane spring 27 interposed is smaller than that of the return spring 21, first the urethane spring 27 is released. When it is compressed by a predetermined amount and the spring constant increases, the descent is started, so that the container 20 descends later than the punch 26.

Therefore, the mandrel 18 and the punch 26
Since the mandrel 18 is fixed on the lower bolster 14, the rough material 22 pinched between and is pressed by the upper bolster 13 and the container 20 starts to descend. There is a relative speed difference with 22. As a result, the rough material 22 sandwiched by the punch 26 and the mandrel 18 from above and below and pressed, flows toward the space on the outer peripheral side where the free surface portion remains, contacts the inner surface of the container 20, and contacts the free surface. As the parts decrease, the resistance increases and it becomes difficult to flow.

However, in this embodiment, the container 2 is moved at the lowering speed V1 lower than the lowering speed V2 of the punch 26.
Since 0 is lowered, the rough material 22 contacting the inner surface of the container 20 is pulled by the frictional force with the inner surface of the container 20 and the downward flow (the direction of arrow Wb in the figure) is promoted. Particularly, in the case of this embodiment, when the rough material 22 that is pinched and deformed by the preceding punch 26 comes into contact with the inner surface of the container 20 and the resistance increases, the container 20 delays and starts descending. Therefore, the material is effectively flowed into the lower corner portion.

In this way, the container 2
Since 0 is relatively moved while forging is performed, it is possible to manufacture a good forged product having no thin portion by a relatively low pressure.

Further, FIG. 3 shows a third embodiment of the closed forging die structure of the present invention. In this embodiment, the structure is such that the filling property of the material in the upper corner portion is enhanced.
The same components as those in the first embodiment will be designated by the same reference numerals, detailed description thereof will be omitted, and description will be given with reference to the drawings.

At the center of the lower surface of the upper bolster 13, a cylindrical punch 36 is mounted vertically with its upper end supported, and below the punch 36, a cylindrical mandrel having the same thickness as the punch 36. 38 is disposed on the same axis as the punch 36, and further, the urgent spring 3 is provided between the mandrel 38 and the lower bolster 14 serving as a reaction force receiving portion.
7 is installed. A cylindrical container 30 is provided on the outer circumference of the punch 36 and the mandrel 38 so as to close the side of the space between the lower end of the punch 36 and the upper end of the mandrel 38. It is fixedly provided on the upper surface.

Then, when the punch 36 descends by being driven by the upper press ram 11, the mandrel 38 is deformed by the deformation resistance of the rough material 22 which is pinched between the mandrel 38 and the mandrel 38.
The mandrel 38 moves relative to the fixed container 30 by compressing and lowering the urethane spring 37.

Next, the operation of the third embodiment constructed as described above will be explained. The punch 36 and the mandrel 38 are described.
The rough material 22 is loaded into the space between and, and the closed forging process is performed. At this time, first, the punch 36 is driven by the upper bolster 13 to descend at the speed V2. Therefore, when the lower end of the punch 36 that descends at the speed V2 comes into contact with the rough material 22, the urethane spring 37 is compressed by the deformation resistance of the rough material and the mandrel 38 is pushed down.

Therefore, since the container 30 is fixed, a relative speed difference is generated between the coarse material 22 descending together with the mandrel 38 and the container 30. As a result, the coarse material 22 that descends while being sandwiched from the vertical direction by the punch 36 and the mandrel 38 flows toward the space on the outer peripheral side where the free surface portion remains, and flows as the free surface portion decreases. It will be difficult. However, in this embodiment, since the coarse material 22 descends with the container 30 fixed, the coarse material 22 contacting the inner surface of the container 20 is pulled upward by the frictional force, and Material flow is promoted into the corners of the.

As a result, the container 30 is used against the rough material 22.
Since the forging is carried out while moving relatively, it is possible to manufacture a good forged product having no thin portion by a relatively low pressure.

FIG. 4 shows a fourth embodiment of the present invention. In each of the above-mentioned embodiments, one of the containers 20, 30 and the rough material 22 is placed above or relatively to the other. It is moved downward so as to promote the flow of the material to the upper or lower corners, but in this embodiment, from the time when the upper press ram 11 starts descending to the time when the bottom dead center is reached. First, one of the container 20 and the rough material 22 is moved relatively upward or downward with respect to the other, and thereafter, it is relatively moved downward or upward. That is, the flow of the material to both the upper and lower corners is promoted, the same components as those in the second embodiment are designated by the same reference numerals, and the detailed description thereof will be omitted. It will be described with reference to the drawings.

At the center of the lower surface of the upper bolster 13 of the press machine, a cylindrical punch 26 is vertically mounted with its upper end supported, and a cylindrical container pushing member 25 is provided on the outer periphery of the punch 26. It is mounted concentrically.

Below the punch 26, a cylindrical mandrel 38 having the same thickness as the punch 26 is formed between the lower bolster 14 serving as a reaction force receiving portion and a material having a rectangular cross section. A coil spring 39 having a modified cross section for loading is provided so as to be movable in the vertical direction. Further, a cylindrical container 20 is provided on the outer circumference of the punch 26 and the mandrel 38 so as to close the outer circumference of the space between the lower end of the punch 26 and the upper end of the mandrel 38. A return spring 21 is interposed between and so as to be slidable in the vertical direction.

A cylindrical urethane spring 27 is sandwiched between the upper end of the container 20 and the lower end of the container pushing member 25. The spring constant of the urethane spring 27 is the return value. Spring 21
Is set to be slightly smaller than the spring constant of. for that reason,
When the container pushing member 25 is lowered, the return spring 21 is compressed while compressing the urethane spring 27.
Is compressed, the descending speed of the container 20 is reduced.

Further, the mandrel 38 and the lower bolster 1
The spring constant of the irregular cross-section coil spring 39 interposed between the rough material 22 and the rough spring 22 is increased by the pressing of the descending punch 26 to cause the rough material 22 to undergo plastic flow and deform. It is set to start contraction when the deformation resistance increases to a predetermined value.

Next, the operation of the fourth embodiment constructed as described above will be explained. The punch 26 and the mandrel 38 are described.
The rough material 22 is loaded into the space between and, and the closed forging process is performed. At this time, first, the punch 26 and the container pushing member 25 are driven by the descending upper bolster 13 to descend. Therefore, the punch 26 descends at the speed V2, and the rough material 22 is compressed between the punch 26 and the mandrel 38. In this state, the irregular cross-section coil spring 39 having a large spring constant is hardly compressed.

On the other hand, the container pushing member 15 which is driven by the upper bolster 13 and descends pushes down the container 20 via the urethane spring 27, but the urethane spring 27 interposed has a spring constant higher than that of the return spring 21. Since the deformation is small, the descending speed is reduced by the deformation, and the container 20 descends at the speed V1.

Therefore, a relative speed difference is generated between the punch 26 and the container 20 (V1 <V2). as a result,
The rough material 22 sandwiched and compressed by the descending punch 26 and the mandrel 38 from the vertical direction flows toward the space on the outer peripheral side where the free surface portion remains, and becomes harder to flow as the free surface portion decreases. . At this time, a relative speed difference is generated between the coarse material 22 compressed on the stopped mandrel 38 and the container 20 which is decelerated and descends, and the coarse material 22 contacting the inner surface of the container 20 is The material is drawn relatively downward (in the direction of arrow Wb in FIG. 4) by the frictional force, and the material flows and fills the lower corner portion of the space.

When the upper press ram 11 further descends and the deformation resistance of the rough material 22 increases, the coil spring 39 having the irregular cross section is compressed and the mandrel 38 and the punch 26.
It descends at a speed V3 almost equal to. Therefore, a relative speed difference (V1> V3) occurs between the container 20 that is decelerated and descends, and the coarse material 22 that descends together with the mandrel 38, and the coarse material 22 that contacts the inner surface of the container 20 is frictional force. Since the material is relatively drawn upward (in the direction of arrow Wa in FIG. 4) and the material flows into the upper corner portion of the space to be filled, therefore, according to the closed forging die of this embodiment, the upper press ram 11 has one stroke. During that time, the flow of the material in both directions in the closed forging die is promoted, so that the upper and lower corners are filled with the material, and a good forged product without defects can be manufactured.

In each of the above-mentioned embodiments, the case where the material flow is promoted upward or downward, or both up and down in the closed forging die has been described as an example. However, regarding the direction of promoting the material flow, The optimum direction can be selected according to the shape of the forged product.

In each of the above-described embodiments, the case where the coil spring, the urethane spring, or the coil spring having a modified cross section is used as the holding member has been described, but as another example of the holding member, a fluid filled liquid cushion or an air cushion is used. There are various rubber materials such as silicone rubber.

[0050]

As described above, according to the closed forging die structure of the present invention, one or both of the mandrel and the container are provided so as to be movable in a direction parallel to the moving direction of the punch. Since either or both of the mandrel and the container are configured to be driven by the press ram of a press machine for forging, a relative speed difference is generated between the rough material and the container, and a relatively low pressure is generated. The closed forging process performed in (1) can be performed using an ordinary press machine.

[Brief description of the drawings]

FIG. 1 is a sectional front view showing a first embodiment of a closed forging die structure of the present invention.

FIG. 2 is a sectional front view showing a mold structure according to a second embodiment of the present invention.

FIG. 3 is a sectional front view showing a mold structure according to a third embodiment of the present invention.

FIG. 4 is a sectional front view showing a mold structure according to a fourth embodiment of the present invention.

FIG. 5 is a sectional front view showing a general example of a conventional closed forging die.

FIG. 6 is a sectional side view showing another conventional closed forging die.

[Explanation of symbols]

 11 Upper Press Ram 12 Lower Press Ram 14 Lower Bolster (Reaction Force Receiver) 16 Punch 18 Mandrel 20 Container 21 Return Spring (Holding Member) 22 Rough Material 26 Punch 27 Urethane Spring (Holding Member) 30 Container 36 Punch 37 Urethane Spring (Holding) Member) 38 Mandrel 39 Deformed cross-section coil spring

Claims (1)

[Claims] 1. A mandrel disposed between a press ram and a reaction force receiving portion facing the press ram, and mounted on the reaction force receiving portion side, and on the same axis as the mandrel mounted on the press ram side. A punch that reciprocates and deforms by sandwiching the rough material between the mandrel and the mandrel, and a cylindrical container provided so as to cover the rough material arranged between the punch and the mandrel from the outside. In the closed forging die structure provided with, one or both of the mandrel and the container, by the holding member different displacement amount due to the pressing force of the press ram, the relative speed difference between the rough material and the container A closed forging die structure, characterized in that it is held so that it can move in a direction parallel to the movement direction of the punch as it occurs.