JPS62173046A - Enclosed forging method - Google Patents

Abstract

PURPOSE:To prevent the generation of a failure of a formed part caused by a deformation of an R part of a punch, by using a punch which has provided a down plane part projected to the outside of an external form of the formed part, on both side ends of the R part, and bringing a burr generated due to this plane part to blanking in the succeeding process. CONSTITUTION:A partially formed part W2 which has been forged and formed is set into a formed part forging die 11 which has been fixed to a holder 2, and a formed part W3 is forged and formed by using a punch 15 which has provided a down plane part 15a on both side ends of an R part. Subsequently, the obtained formed part W3 is set to a deburring die, and a burr (a) of the formed part W3 is removed by the punch. In this way, in case of enclosed forging, a deformation of the R part of the punch 15 is avoided, and also, the generation of a failure of the formed part caused by the deformation of the R part of the punch is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a closed forging method for forming a yoke for a universal joint used, for example, in the main shaft of a vehicle steering wheel.

(Prior Art) Generally, when a molded product such as the above-mentioned yoke is formed by forging, many burrs are generated on the outer peripheral portion of the molded product. For this reason, deburring is performed in the finishing process after forging, but this reduces the yield of the molded product material by 50% or more.
Very low at 70%.

Therefore, conventionally, a semi-formed product W2, which is previously forged into a predetermined shape using a closed-type die 31 and a punch 35 shown in FIGS. 7(A) and 7(B), is produced as shown in FIG. 'J:
The punch 35 is lowered toward the semi-formed product W2 as shown in FIG. 7(B), thereby forging the molded product W shown in FIG. 8.

(Problems to be Solved by the Invention) A molded product W such as a yoke has a cylindrical portion Wa on the right side as shown in FIG. For this reason, the punch 35 is provided with eight parts 35a for forming the cylindrical part Wa, as shown in FIG. Therefore, as shown in Fig. 10, it is conceivable to provide a downward flat part at the tip of the 8 part 35a, but when punched with such a punch, as shown in Fig. 11, An extra protrusion B is formed on the product.This protrusion B may cause problems such as interference with the V bevel of the processing standard or interference with mating parts when the molded product is assembled, resulting in malfunctions during operation. be.

The object of the present invention is to provide a closed forging method that does not cause deformation of the R portion in the process of forging a molded product having a cylindrical shape using a closed type die and punch.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a process for forging a molded product using a closed type die and a punch having an R portion forming a cylindrical surface. This is a closed forging method characterized by using a punch with downward flat parts projecting outward from the outside of the molded product at both ends, and punching out burrs caused by these flat parts in the next step.

(Example) Hereinafter, the closed forging method of the present invention will be specifically described based on drawings showing examples of forging of a yoke for a universal joint used in a main shaft of a vehicle steering wheel.

First, as shown in FIG. 3(A), a die 1 for forging a semi-formed product is attached to a clamp 3 and fixed to a holder 2.
1, one material W1 is set as shown in FIG. 1 (A>).

, /I is a knockout pin that is 3ffl later. Next, operate the press machine.
1, as shown in FIG. 3(B), the semi-formed product W2 shown in FIG. 4(B) is forged.

Next, this semi-formed product W2 is set in a die 11 for forging a molded product, as shown in FIG. 5 (Δ).

This die 11 is also shown in FIG. 3(A).

As in the case of the die 1 shown in (B), it is fixed to the holder 2 by a clamp 3. The punch 15 used for finishing forming is provided with downward flat parts 15a at the lower ends of both sides of the R forming part.

As shown in FIG. 1, the flat portion 15a is located on the outside of the width of the molded product. This punch 15 is shown in Figure 5 (B).
By lowering it as shown in FIG. 1, the molded product W3 shown in FIG. 1 is forged. At this time, as is clear from FIG. 1, the molded product W3 is under tension in a direction perpendicular to the operating direction (up and down direction) of the punch 15 in the forging process shown in FIGS. 5(A) and 5(B). The barrier to be released is molded.

In addition, Fig. 3 (A>, (B) and Fig. 5 (A), (B)
), the knockout pin 4 provided on the holder 2 side is used to forge a semi-formed product W2 or a molded product W3 with each die 1°11, and then push it up and take it out from each die 1°11. It is for.

Next, to explain the process of removing the barrier of the molded product W3 that has been forged as shown in FIG. It is set in a deburring die 21 fixed with a clamp 3. At this time, the molded product W3 is supported with respect to the die 21 only by the barrier portion. Therefore, as shown in FIG. 6(B), the punch 25 is
Move down. Since the width of the punch 25 is set to the dimension excluding each barrier a of the molded product W3, the molded product W3 is formed by inserting the barriers a into the die 2 as shown in FIG.
The burr is left on the burr support portion (not shown) of No. 1 and punched downward. As a result, the barrier will be properly removed from the molded product W3.

(Effects of the Invention) As explained above, the present invention provides a process for forging a molded product using a closed type die and a punch having an R section for forming a cylindrical surface, at both ends of the R section. This is a closed forging method characterized by using a punch with a downwardly facing flat part that protrudes outside the outer shape of the molded product, and punching out burrs caused by punching on this flat part in the next process. This has the effect of preventing defects in the molded product due to deformation of the R portion and improving the durability of the punch.

[Brief explanation of drawings]

1 to 6 show examples of the present invention, FIG. 1 is a perspective view showing a punch for forging and a molded product, and FIG. 2 is a perspective view of a molded product with burrs punched out. , Figure 3 (A
), (B) are cross-sectional views showing the forging process of the semi-molded product, FIG. 4(A) is a perspective view of the material, FIG. 4(B) is a perspective view of the semi-molded product, and FIG. 5( △) and (B) are cross-sectional views showing the forging process of molded products, and Fig. 6 (A>, (
B) is a cross-sectional view showing the deburring process for a molded product, FIGS. 7(A) and (B) are cross-sectional views showing the conventional forging process for a molded product, and FIG. 8 is a cross-sectional view showing the conventional forging process. FIGS. 9 and 10 are perspective views showing the R portion of a conventional punch, and FIG. 11 is a perspective view of a molded product formed using the punch of FIG. 10. 11...Dice 15...Punch 15a...Flat part 21...Deburring die 25...Deburring punch W3...Molded product a...Burr Applicant 1-Yota Jidosha Co., Ltd. Agent Patent Attorney Hidehiko Okada (2 others) Figure 1 Figure 2 Figure 3 (A) Figure 4 (A) Figure 3 (B) Figure 4 (B) Figure 5 (A) Figure 6 (A) Figure 5 (B) Figure 7 (B) Figure 7 (A) Figure 7 (B) Figure 9 Figure 10

Claims (1)

[Claims] In the process of forging a molded product using a closed-type die and a punch having an R portion that forms a cylindrical surface, a punch is used that has downward flat portions protruding outside the outer shape of the molded product at both ends of the R portion. , a closed forging method characterized by punching out burrs caused by this flat part in the next step.