JPS59156532A - Forging punch - Google Patents

Abstract

PURPOSE:To extend the life of a punch by dividing a punch holder and a punch body to avoid stress concentration in a corner part. CONSTITUTION:A forging punch 1 is so formed that the top surface of a punch holder 1d is made flush with the top surface of a body 1b in the state of fitting the body 1b into the central hole of the holder 1d. Then the corner part 1c of the body 1b exists in the holder 1d and can be made to have a large radius R of curvature without being affected by the shape of a forging. Since the corner part 1c exists in the holder 1d, said part does not directly contact the forged product and is kept free from a thermal damage. The concentration of stress in the corner part 1c is avoided and the life of the punch is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a forging punch, and particularly to a forging punch that is of a split type to increase the number of punches.

As shown in FIG. 1, a die punch for ordinary die forging has a mounting portion 1a and a main body 1b integrally formed, and has a T-shaped cross section. When forging is performed using such a punch 1, a stress concentration of mechanical stress and thermal stress occurs at the corner IC, and when stress exceeding the material proof stress is applied, cracks (heat scratches) occur from the corner 1c. , damaging the punch 1. Damage caused by this stress concentration is particularly severe under the condition that t/d>0.80 with respect to the diameter of the punch 1 (body diameter). It was possible to forge only a few hundred to 2,000 molds per piece.

Therefore, in order to increase the number of lives, it is conceivable to increase the radius of curvature Re of the core portion 1c, for example, by setting the radius of curvature R) to 20 mm to improve the material yield strength. The increase in the radius of curvature R at the corner 1c also depends on the relationship t/d between the length t and diameter d of the punch, but for example, if ft = 5 m+ ~ 20 mm, the stress concentration factor It will decrease by about 20%. However, in the punch 1 having the configuration shown in Fig. 1, if the radius of curvature at the corner IC is simply increased, the absolute number of punches will be as small as about 2,000, so increasing the number of punches by about 20% will not result in a significant improvement. .

Also, depending on the forged product, the radius of curvature R of the corner IC cannot be increased unnecessarily due to the need for machining.
There is also a limit to the increase in the radius of curvature R. In addition, Fig. 2(a)
(b) shows an overview of the forging process;
(b) shows the product after forging.

In view of the above-mentioned drawbacks, the present invention aims to provide a forged punch that prevents damage to the punch and increases its life.

In order to achieve this object, the present invention features a forging punch in a forging die in which the punch holder and the punch body are separated.

The present invention will now be described in detail with reference to FIGS. 3 and 4. Note that the same parts as in FIG. 1 are given the same reference numerals. In Fig. 3, the punch 1 is of a split type, with a punch body 1b.
and a punch holder 1d. . That is,
It has a structure in which the punch body 1 is fitted into the center hole of the punch holder ld, and when fitted, the punch holder 1d
The upper surface and the upper surface of the punch body 1b are formed to be on the same plane. For fitting, the upper part of the corner part 1c with a large radius of curvature R formed on the upper part of the punch body 1b is used as the mating surface with the punch holder 1d. In the case of a punch, the corner IC of the punch body 1'b becomes a trap if it exists inside the punch holder ld, so it is possible to have a large radius of curvature R regardless of the shape of the forged product, as in the conventional case. By the way, it is only necessary to fit the upper edge punch holder 1dK of the punch body 1b and have a large radius of curvature, so there is no need to make the attachment part la (see Figure 1) have a long protruding structure as in the past. A structure that protrudes left and right (see Figure 3) is sufficient. Note that the function of the conventional mounting portion 1a is performed by a punch holder 1d, and this I-inch holder 1d also has the role of supporting and positioning the punch body 1b.

Note that the lower surface of the punch holder 1d is a surface perpendicular to the punch body 1b. Further, fixing to the die holder is performed by a punch holder 1d.

According to such a structure, the corner portion 1 of the punch body 1b
Since point c is located within the punch holder and does not come into direct contact with the forged product, the corner IC is hardly subjected to thermal stress and is not damaged by heat. Further, the radius of curvature R of the corner portion 1c is not affected by the shape of the forged product as in the conventional case, so it can be set to a safe value in terms of design, and damage caused by mechanical load stress can be prevented. This mechanical stress is related to the degree of left and right protrusion of the upper part of the punch body 1b, but the left and right (
3), the mechanical stress applied to the corner portion 1c is reduced together with the above-mentioned increase in the radius of curvature, which is also very effective in preventing damage.

When an unbalanced load is applied to the punch 1, stress concentration occurs at the corner in the conventional case, but in this embodiment, the punch holder 1d and the punch body 1b are separate bodies, and the upper surface of the punch body 1b is aligned with the diameter of the punch body 1b. Since it does not change much, stress concentration on the corner portion 1c can be avoided. In addition, since the punch 1 is a split type, when forming the punch 1, the remainder of the die shape can be used for mold processing, and furthermore, the wear of the punch can be reduced by reducing the wear of the punch body 1b. By replacing this part, the amount of expensive molding material used can be reduced.

FIG. 4 shows a punch body 1 of a punch 1 in another embodiment of the present invention.
b has a cylindrical shape (or may be a square prism), and this pinch body '1b is fitted into the center hole of the punch holder 1d. In this case, since the punch body 1b does not have any curvature, it is necessary to fasten both the punch body 1b and the punch holder 1d to the die holder using bolt connection buttons or the like. Since this structure has no corners, the problem of stress concentration does not occur, and it is more effective than the mold shape shown in FIG. 3 as a measure to improve uneven loads.

It goes without saying that the inch holder ld is used to adjust the position of the punch body 1b and to attach it to the forging machine.

FIG. 5 shows the difference in the number of punch dies when the conventional punch and the punch according to the embodiment of the present invention are actually forged. In this Figure 5, the forging temperature is 1250℃, the die material is 5KD62,
This is a comparison under the condition that the forged material 848C-i was used, and the resink t was performed once, in which a die worn out during forging was machined to standard dimensions. In FIG. 5, R=3, R=5, and R=10 indicate the radius of curvature R(,,) of the coach portion IC of the punch shown in FIG. The third night is the value for the split type punch 1 in FIG. 2 and punch 1 in FIG. 3, respectively. As can be seen from Figure 5, the number of lives was significantly different, and we were able to improve the number of lives to 8,000. Note that the punch body can be applied even if it has a complicated shape.

As explained above, according to the present invention, the disadvantages caused by stress concentration at the corners, which had been a problem in the past, can be prevented by creating a split type pinch with a pinch holder and the punch body, thereby improving the life of the punch. This reduces the need for mold materials, processing materials, maintenance, etc., and allows the production of many forged products using the same mold, which directly leads to cost reduction and makes a significant social contribution.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional forged punch, Figure 2 (jL)
(b) is a forging process diagram, FIGS. 3 and 1M4 are sectional views showing two embodiments of the forging punch according to the present invention, and FIG. This is a bar graph showing the results. In the drawings, 1 is a punch, 1b is a punch body, 1c is a corner portion, and 1d is a punch holder. Patent applicant: Mitsubishi Heavy Industries, Ltd. Mitsubishi Motors Corporation, sub-agent Patent attorney: Shibu Mitsuishi (and one other person) No. 1 Diagram 2 (a)
(b) Figure 3: Figure 4: Figure 5: R-3R-5R-10-21! l Continued from page 1 of I3N 0 Author: Yamada Omote 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Mitsubishi Heavy Industries, Ltd. Hiroshima Research Center 0 Author: Mitsubishi Hirakuni Akira, 1 Mizushima Kaigandori-chome, Kurashiki City Inventor: Masataka Kasai, Mizushima Kaigan-dori-1-chome, Kurashiki-shi Inventor: Masataka Nagase, Mizushima Kaigan-dori-1, Kurashiki City, Mizushima Auto Works, Mitsubishi Motors Corporation People Mitsubishi Motors Corporation 5, Shiba, Minato-ku, Tokyo
Chome 33-8

Claims (1)

[Claims] A forging punch in a forging die, characterized in that a punch holder and a punch body are separated.