JPH0744350Y2 - Forging die - Google Patents

Description

TECHNICAL FIELD The present invention relates to a structure of a forging die for so-called flash forging, which is one of die forgings.

Conventional technology and its problems In the overhang forging method (semi-closed forging method), as shown in FIGS. 3 (A) and 3 (B), the material W preliminarily processed in the previous step (rough land step) is used as the upper die. 1 and the lower mold 2 are pressed and constrained to mold into a predetermined product shape. Normally, at the end of molding, a gap C is formed on the mold split surface between the upper and lower molds 1 and 2 as a flash path. Thus, the bottom dead center position of the upper die 1 is set. That is, the presence of the gap C positively allows the occurrence of the flash (excessive thickness) F to absorb the variation in the material volume.

In the conventional forging method as described above, as is clear from FIG. 3 (A), since the clearance C ₁ at the initial stage of molding is large, the product part space R is filled with the material meat sufficiently. The flash F is generated, and the volume that finally becomes a surplus is large and the material yield is poor.

On the other hand, for the purpose of reducing the above-mentioned flash as much as possible, for example, a forging die of Japanese Utility Model Application No. 61-71716 has been proposed by the present applicant. In this die structure, one of the upper die and the lower die is divided into an inner punch that presses and restrains the central portion of the material, and an outer punch that presses and restrains the outer peripheral edge portion of the material. The outer punch contacts the other mold from the initial stage of forming to form a sealed product space, while it is separated from the other mold at the final stage of molding to prevent burrs from forming between the other mold. The inner punch is slidably and elastically supported so as to form an allowable flash path.

According to such a die structure, since a substantially closed structure is formed during molding and burrs are generated only at the final stage of molding, burrs are remarkably smaller than those of conventional flash forging.

On the other hand, on the contrary, since the flash is small, it is difficult to trim in the post-process. Especially, if the flash volume and thickness are extremely small and the rigidity of the flash itself is not sufficient, the flash will not be trimmed when sheared by the trim mold. Bite between the cutting edges,
Alternatively, slippage may occur between the cutting edge and the burrs, and the burrs may not be cut and removed cleanly from the boundary with the product shape section.

The present invention is based on the mold structure of Japanese Utility Model Application No. 61-71716, and provides a mold structure that facilitates trimming in a later step.

Means for Solving Problems In the forging die of the present invention, the upper die is divided into an inner punch that presses and restrains the central portion of the material and an outer punch that presses and restrains the outer peripheral edge portion of the material. is doing.

The outer punch contacts the lower mold from the initial stage of forming to form a sealed product space, while at the end of molding, the internal pressure of the product space increases to raise the inner space from the lower mold by a predetermined amount. It is slidably supported with respect to the inner punch through an elastic body that urges the outer punch downward so as to form a flash path that allows the occurrence of flash on the split surface between the lower punch and the lower mold. ing.

Further, in the vicinity of the molding surface of the molding surface of at least one of the lower die and the outer punch, a flash that is continuous with the flash path while forming a part of the product part space and is generated in the flash path. At the same time, it is characterized in that a stepped portion is formed integrally with a peripheral portion of the product shape portion to be cut and removed in a subsequent step.

The stepped portion may be formed on both the lower die and the outer punch.

Action As is apparent from FIGS. 1 (A) and 1 (B), when the outer punch contacts the lower die, it becomes a substantially complete hermetic forging until the raw material meat fills the product space. There is no room for flash to occur on the parting surface. Then, when the entire material space including the stepped portion is filled with the raw material meat at the final stage of molding, the outer pressure of the outer punch is moved upward for the first time to allow the occurrence of burrs on the burrs formed on the mold splitting surface. As a result, when the shape of the stepped portion is transferred, burrs are generated continuously in the stepped portion formed on the peripheral portion of the product shape portion.

Therefore, in the subsequent process, when removing the flash, the step itself is provided with sufficient rigidity by cutting and removing the flash along with the step attached to the product shape section from the boundary between the product shape section and the step. Since it has, the trimming property is improved as compared with the trimming by the flash alone.

Embodiments FIGS. 1A and 1B are views showing an embodiment of the present invention, in which an upper die 3 includes an inner punch 4 for pressing and restraining a central portion of a material W and an outer portion of the material W. It is divided into a cylindrical outer punch 5 that pressurizes and restrains the peripheral portion, and the inner punch 4 is fixed to a press ram 7 by a holder block 6. The outer punch 5 is vertically movable with respect to the inner punch 4, and is supported by a lower holder 8 fixed to a holder block 6. A disc spring 9, which is an elastic body, is interposed between the holder block 6 and the outer punch 5, and the disc punch 9 biases the outer punch 5 downward.

On the other hand, the mold splitting surface 10 of the molding surface 2a of the die 2 as the lower mold
In the vicinity of, a stepped portion 11 is formed so as to cut off a part of the molding surface 2a. This stepped portion 11 is shown in FIG.
As shown in, the die 2 and the outer punch 5 are separated from each other by the mold dividing surface 10
When the outer punch 5 is lifted from the die 2 by a predetermined amount as shown in FIG. 1B, it forms a part of the sealed product space R when they are in contact with each other. It will be continuous with the gap C as a flashway formed on the surface 10.

In such a die structure, since the tip of the outer punch 5 is always located lower than the tip of the inner punch 4, when the upper die 3 is lowered with respect to the die 2, the outer punch 5 is first moved. The outer peripheral edge portion of the material W is pressed and restrained by coming into contact with the die 2, and then the inner punch 4 pressurizes and restrains the central portion of the material W. That is, the first
As shown in FIG. 1A, the outer punch 5 comes into contact with the die 2, so that the product space R becomes a completely closed space, and the inner punch 4 gradually descends together with the press ram 7. The material W is relatively moved upward while being in close contact with the die 2, and the material W is crushed to fill the product space R.

At this time, since the stepped portion 11 forms a part of the sealed product space R, the stepped portion 11 is also filled with the material meat, and the shape of the stepped portion 11 remains the same as the material W. The stepped portion 11 is transferred to the peripheral portion of the product shape portion Q (material W).
The stepped portion M as a non-product portion corresponding to the shape of is integrally formed.

As shown in FIG. 1 (B) at the end of molding, when the raw material meat fills the product space R, the internal pressure increases, and the disc spring 9
The pushing force of the outer punch 5 due to the internal pressure is larger than the downward pushing force of the outer punch 5 due to. As a result, the outer punch 5 is pushed up by a predetermined amount just before the upper die 3 reaches the bottom dead center, and the outer punch 5 and the die 2 are pushed.
Since a clearance C as a flash path is formed on the mold splitting surface 10 between the and, a flash (surplus thickness) F is formed continuously from the clearance C to the step M.

Here, considering only the flash F generated in the gap C,
Although its volume is extremely small, it is advantageous in terms of material yield, but it is difficult to perform trimming in a post process. This is as described above.

On the other hand, in the part of the product P after forging corresponding to the stepped portion 11, the stepped portion M as a non-product portion which is continuous with the product shaped portion Q is integrally formed so that the shape of the stepped portion 11 is transferred. Unlike the thin beam F that extends horizontally in the gap C, the stepped portion M is in close contact with the product shape portion Q as a part of the product shape portion Q and has a sufficient sense of rigidity.

Therefore, after the product P is taken out from the die 2, for example, as shown in FIG. 2, the step M is trimmed so as to be scraped off along the outer peripheral surface of the product P (product shape part Q) from the a direction. Not only the part M but also the flash F is trimmed at the same time and removed from the product shape part Q.

Similar effects can be obtained when the stepped portion 11 is provided on the outer punch 5 side or both the die 2 side and the outer punch 5 side.

Further, as described above, the shape of the product P (product shape portion Q) changes due to the outer punch 5 rising by a predetermined amount in the final stage of molding, but the outer punch 5 is lifted by 1 to
Even though the outer punch 5 is lifted up, it is only 3 mm, and the center portion of the product P is completely constrained by the inner punch. It is well within the range allowed as a general dimensional intersection.

That is, the influence of the rise of the outer punch 5 on the shape or size of the product P can be regarded as the inner punch 4 is immovable when the outer punch 5 is raised, so that the die split surface 10 of the die 2 and the outer punch 5 are not affected. The volume of the molded product P slightly fluctuates between the two, which is within a practically sufficient range.

Furthermore, the variation in the volume of the individual material W before forging is managed in advance to the extent that it appears as the variation in the volume of the entire surplus portion to be the flash F and the step M after the forging. It goes without saying that the material W does not have such a large variation that the variation in the material W appears as a lack of thickness in the product shape portion Q.

As described above, according to the present invention, the outer punch contacts the lower mold from the initial stage of molding to form a sealed product space, while at the end of molding, the internal pressure of the product space increases. Is supported slidably with respect to the inner punch through an elastic body so as to form a flash path that allows the flash to rise by a predetermined amount, and at least one of the lower die and the outer punch is molded. In the vicinity of the parting surface of the surface, a step portion which is continuous with the burr path while forming a part of the product part space and which is to be cut and removed in a later step together with the burr generated in the burr path is formed in the product shape part. The stepped portion is formed integrally, and the stepped portion to be removed together with the flash as a surplus during trimming is previously formed integrally with the product shape portion.

Therefore, not only can the surplus volume be reduced and the material yield can be improved, but since the step portion to be removed together with the flash has sufficient rigidity, it has good trimability, In addition, the flash does not get caught between the cutting blades during the shearing by the trim mold, or the sliding between the cutting blades does not occur, and the flash can be cleanly cut and removed from the product shape portion together with the step portion.

[Brief description of drawings]

1 (A) and 1 (B) are sectional views of a die showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a flash, and FIGS. 3 (A) and 3 (B) are conventional forging dies. FIG. 2 ... Die as lower mold, 2a ... Molding surface, 3 ... Upper mold, 4 ... Inner punch, 5 ... Outer punch, 9
...... Belleville spring as an elastic body, 10 ...... mold splitting surface, 11 ...... stepped portion, C ...... gap as burrs, F ...... burrs (excess),
M: step (excess), P: product, Q: product shape,
R: product space, W: material.

Claims (1)

[Scope of utility model registration request] 1. A material (W) is pressed and restrained by an upper mold (3) and a lower mold (2) to be molded into a predetermined shape, and the upper mold (3) and the lower mold (at least at the end of molding). A forging die that allows the generation of flash (F) on the mold splitting surface (10) with 2), wherein the upper die (3) is an inner member that pressurizes and restrains the central portion of the material (W). It is divided into a punch (4) and an outer punch (5) that pressurizes and restrains the outer peripheral edge of the material (W), and the outer punch (5) is changed from the initial stage of molding to the lower mold (2). While forming a sealed product part space (R) by contact, at the end of molding, the internal pressure of the product part space (R) rises so that it rises from the lower mold (2) by a predetermined amount and the mold splitting surface (1
The inner punch (4) through an elastic body (9) that urges the outer punch (5) downward so as to form a flash path (C) that allows the occurrence of flash (F) in (0). Is slidably supported with respect to the product space (R) in the vicinity of the mold split surface (10) of the molding surface (2a) of at least one of the lower mold (2) and the outer punch (5). A part of the product shape part (M) that is continuous with the flash path (C) and that is to be cut and removed in a later step together with the flash (F) generated in the flash path (C). A forging die characterized in that a stepped portion (11) is formed integrally with the peripheral portion of Q).