JPH0715645Y2 - Closed forging machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a closed forging die apparatus, and in particular, it can be press-fitted into an impression part formed between an upper die and a lower die constituting the closed forging die apparatus. The present invention relates to the improvement of a punch having a circular cross section.

[Conventional technology]

In general, closed forging uses a die structure in which an outlet for burr from the inside of the die to the outside is eliminated during forging. An example thereof will be described with reference to FIG. 4 (cross-sectional view) and FIG. 5 (partially enlarged cross-sectional view). The closed forging die apparatus includes an upper die 1 and a lower die 2 and a through hole 1a formed in the center thereof. And 2a, a punch 3 and a punch 4 each having a circular cross-section that can be press-fitted into an impression portion 8 formed between the upper die 1 and the lower die 2.

In the conventional closed forging die apparatus, a clearance of a small dimension a (for example, about 0.1 mm) is provided between the inner peripheral surface of the through hole 1a and the outer peripheral surface of the punch 3 to enable the reciprocating motion of the punch 3. 9 is set.

Needless to say, similar clearances are set for the through hole 2a and the punch 4.

[Problems to be solved by the device]

By the way, in the conventional closed forging die apparatus as described above, since the internal pressure generated at the time of forging is very high, a part of the material 5 flows into the clearance 9 to generate the thin burr 5a. The length b of the thin burr 5a reaches 3 to 5 mm, which hinders the backward movement of the punch 3 after the completion of forming, causing so-called seizure of the die or defective release of the die. There is a problem in that post-processing takes time and labor.

The present invention is intended to solve such a problem, and in a circular cross-section punch in a closed forging machine, a small-sized depth is formed on the entire circumference of the ridge portion where the peripheral side surface and the tip surface intersect. And a step portion having a width are formed, and part of the material flows into the step portion at a relatively early stage of forging,
This causes work hardening and acts as a plug that closes the inlet of the clearance, and prevents a part of the material from flowing into the clearance, thereby preventing the occurrence of thin burrs. The purpose is to provide.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, in the closed forging die device of the present invention, in the die device for closed forging, an upper die and a lower die and an impression portion formed between these upper die and lower die are provided. A die body having the same and a punch having a circular cross-section that can be press-fitted into the impression portion are provided, and a clearance is formed between the peripheral side surface of the punch and the die body so that the punch can reciprocate. Together with the punch, the punch is formed of a rod body having a peripheral side surface parallel to the reciprocating direction and a front end surface perpendicular to the peripheral side surface, and at the ridge portion where the peripheral side surface and the front end surface intersect, A step portion having a minute depth and width and communicating with the clearance is bored along the entire circumference thereof, and the impression material is flowed from the impression portion to the step portion at the time of forging by the molding material. Between ® emission section and the clearance is characterized in that it is configured to be blocked.

[Action]

In the closed forging die apparatus of the present invention described above, since the step portion is formed along the entire circumference of the ridge line portion of the tip surface of the punch, a small part of the material enters the step portion at a relatively early stage of forging. It flows in and stays here. Then, this material is hardened by work hardening and acts as a plug that closes the inlet of the clearance, and prevents the material from flowing out from the impression portion to the clearance.

〔Example〕

A closed forging die apparatus as one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view thereof, and FIG.
The drawing is a partial enlarged side sectional view thereof, and FIG. 3 is a sectional view of the III portion in FIG. 1 during forging.

The closed forging die apparatus of this embodiment also has a structure as shown in FIG.
An upper die 1 and a lower die 2, an impression portion 8 formed between the upper die 1 and the lower die 2, and a punch 3 formed by a rod body having a circular cross section that can be press-fitted into the impression portion 8. And a punch 4, and a through hole 1a and a through hole 2a respectively formed in the upper die 1 and the lower die 2 through which the punch 3 and the punch 4 can pass. Further, the clearances 9 are set between the outer peripheral surfaces of both punches 3 and 4 and the inner peripheral surfaces of through holes 1a and 2a, respectively, which are substantially the same as those in the above-described conventional example.

Further, the ridge line where the tip surface 3a and the peripheral side surface 3b of the punch 3 intersect with each other has a small dimension (for example, 0.5 mm to
A step portion 6 having a depth of 1.0 mm) and a width of almost the same dimension is formed.

It is needless to say that the punch 4 is also formed with the same stepped portion 7.

With the above configuration, the material 5 placed in the impression portion 8 during the forging process is deformed so as to conform to the shape of the inner wall surface of the impression portion 8 as the punches 3 and 4 are pressed inward. At this time, a small part of the material flows into the step portions 6 and 7 at a relatively early stage of this forging process. The material flowing out to the step portions 6 and 7 stays here and gradually hardens due to work hardening and loses fluidity, and has a function as a plug for blocking between the impression portion 8 and the clearance 9. As a result, the material is prevented from flowing into the clearance 9 thereafter.
Therefore, only a small amount of thin burr that has flowed out to the clearance 9 in the initial stage of the forging process remains in the clearance 9. Therefore, the dimension b ₁ of the thin burr 5a including the step is
It is much smaller than the dimension b in the conventional example.

The depth and width of the stepped portion 6 (or 7) are both preferably 0.5 mm to 1.0 mm when the punch diameter is 22 mm to 40 mm, and the inventors of the present invention have found that the closed forging die using the punch having the above-mentioned size. By the equipment, closed forging of the material preheated to about 200 ° C was performed, and a forged product with almost no thin burrs was able to be obtained.

It should be noted that the above-mentioned dimensions of the stepped portion are appropriately selected according to the forming load (these dimensions may be small when the forming load is small), and it is desirable that the angle A is an acute angle. If it is rounded by a finishing file considering breakage, it may be attached.

[Effect of device]

As described in detail above, according to the closed forging die apparatus of the present invention, the following effects and advantages can be obtained.

(1) A small portion of the material flows into the stepped portion that is formed along the entire circumference of the ridge line portion of the punch tip surface and communicates with the clearance at a relatively early stage during the forging process, which causes work hardening and causes clearance Since it acts as a plug that closes the inlet portion, it is possible to prevent the material from flowing out from the impression portion to the clearance, and to prevent the occurrence of thin burrs.

(2) Since it is only necessary to perform a simple process of forming a step portion having a minute depth and width along the ridge line where the tip end surface and the peripheral side surface of the punch intersect, the cost can be reduced. It is advantageous in terms.

(3) Since the occurrence of thin burrs can be prevented, post-processing of the forged product becomes easy.

[Brief description of drawings]

1 to 3 show a closed forging die apparatus as one embodiment of the present invention. FIG. 1 is a side sectional view thereof, FIG. 2 is a partially enlarged side sectional view thereof, and FIG. Figure 1 III
4 is a sectional side view, and FIGS. 4 and 5 show a conventional closed forging die apparatus. FIG. 4 is a side sectional view thereof, and FIG. 5 is a sectional side view of a V portion of FIG. 4 during forging. is there. 1 ... Upper mold, 2 ... Lower mold, 1a, 2a ... Through hole, 3,4 ... Punch, 3a, 4a ... Tip surface, 3b, 4b ... Peripheral side surface, 5 ... Material, 6, 7 ... step, 8 ... impression, 9 ...
…clearance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 61-3627 (JP, A) JP 62-77143 (JP, A) JP 63-20137 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A mold apparatus for closed forging, wherein a mold body having an upper mold and a lower mold and an impression part formed between the upper mold and the lower mold, and the mold body can be press-fitted into the impression part. A punch having a circular cross-section is formed, and a clearance is formed between the peripheral side surface of the punch and the die body so that the punch can reciprocate, and the punch is parallel to the reciprocating direction. It is formed from a rod body having a peripheral side surface and a tip surface perpendicular to the peripheral side surface, and at the ridge line portion where the peripheral side surface and the tip surface intersect with each other, the clearance and the clearance are provided with a minute dimension. A step portion communicating with the step portion is bored along the entire circumference thereof, and a molding material flowing out from the impression portion to the step portion during forging is used to seal between the impression portion and the clearance. Wherein the configured, enclosed forging type device.