JP2506593B2 - Closure forging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed forging device,
More specifically, the present invention relates to a closed forging device in which a recess effective for forming a large-diameter shaft hole is formed on both end surfaces of a billet by closed forging prior to punching the shaft hole.

[0002]

2. Description of the Related Art As an example of a method for forming a shaft hole in a billet made of a hard material, the applicant of the present application has proposed a method for punching out the shaft hole of a spider for a constant velocity joint (Japanese Patent Application No. 2- 68742). FIG. 7 shows this constant velocity joint spider 10. The constant velocity joint spider 10 includes a boss portion 14 having a shaft hole 12, and a boss portion 14
A plurality of roller shafts 16a to 16c provided on the outer peripheral surface of the roller
Consists of

First, a material such as a billet is subjected to closed forging to form an intermediate body 20 having recesses 18a and 18b on both end surfaces corresponding to the boss portion 14, as shown in FIG. Next, the space between the recesses 18a and 18b of the intermediate body 20 is removed by using a punch punch to form the shaft hole 12. It should be noted that the recesses 18a, 1 are formed in the intermediate body 20 by the closed forging.
The purpose of providing 8b is to reduce the load when punching the shaft hole 12.

[0004]

By the way, in forming a large-diameter shaft hole in forming the spider for a constant velocity joint, etc., the depth and diameter of the recess are also determined according to the diameter of the shaft hole during closed forging. It needs to be large.

However, it has been pointed out that when such a large-diameter deep recess is formed by closed forging, the disadvantage of cracks occurring at the peripheral edge of the recess is very difficult to form a large-diameter shaft hole. In particular, when the step h of the recesses 18a and 18b with respect to the roller shafts 16a to 16c becomes large, the influence becomes remarkable.

Therefore, according to the present invention, in order to overcome the above-mentioned inconvenience, it is possible to provide a recess having a depth and a diameter effective for forming a large-diameter shaft hole without forming a crack. An object of the present invention is to provide a closed forging device.

[0007]

In order to solve the above-mentioned problems, according to the present invention, prior to the punching of the shaft hole, a punch is provided at a portion corresponding to the shaft hole on both end faces of a billet held by a die. In a closed forging device that press-fits to form a recess, the center portion of the tip of the punch is a curved surface with a large radius, and the peripheral portion of the tip is a curved surface with a radius smaller than the central portion. To do.

[0008]

In the closed forging device according to the present invention, prior to the punching of the shaft hole, the center portion of the tip of the punch is formed of a curved surface having a large radius, and the peripheral portion of the tip has a diameter smaller than that of the center portion. By forging the billet with a punching punch having a curved surface with a large radius, a crack having a depth and a diameter effective for drilling a large-diameter shaft hole is formed in both end faces of the billet. Can be formed without. Then, a large diameter shaft hole can be obtained by press-fitting the punching punch with the center line of the punching punch aligned with the recess.

[0009]

The preferred embodiments of the closed forging device according to the present invention will now be described in detail with reference to the accompanying drawings.

In this embodiment, a closed forging device for forming a constant velocity joint spider will be described.

In FIG. 1, reference numeral 30 indicates a closed forging device for manufacturing the spider 10 for a constant velocity joint shown in FIG. The closed forging device 30 basically includes an upper die 32, a lower die 34, and a space portion 36 having an intermediate body shape described later, which is arranged in a mechanical or hydraulic press device (not shown). A cavity 32a formed in the center of each of the upper die 32 and the lower die 34,
The hollow cylindrical guide members 38 and 40 are detachably inserted into the guide member 34a, and the upper forging punch 42 and the lower forging punch 44 are detachably inserted into the hollow portions of the guide members 38 and 40.

FIG. 2 shows an upper forged punch 42 and a lower forged punch 4.
4 is shown. Since the upper forging punch 42 and the lower forging punch 44 have exactly the same shape, the same components will be denoted by the same reference numerals in the following description, and redundant description will be omitted.

The upper forging punch 42 and the lower forging punch 4
4 is basically composed of a cylindrical portion 46 and a tip portion 48, and the tip portion 48 is 5/5 with respect to the diameter D of the cylindrical portion 46.
A central curved surface portion 50 formed of a curved surface having a large radius R set to 4 times, and a small radius r located at the peripheral portion of the central curved surface portion 50 and set to 1/3 times the diameter D. And a peripheral curved surface portion 52 formed of a curved surface. Further, between the cylindrical portion 46 and the peripheral curved surface portion 52, an inclination α (≈) is formed so that the diameter is directed from the cylindrical portion 46 toward the peripheral curved surface portion 52 and has a small diameter.
The taper surface 46a set to 4 ° is formed.

The closed forging device 30 of this embodiment is basically constructed as described above. Next, the forming process of the spider 10 for a constant velocity joint using the closed forging device 30 and its action. The effect will be described.

When molding the spider 10 for a constant velocity joint using the closed forging device 30, first, the space 3 is formed.
The billet 35 is inserted into 6. Then, a cavity 32a formed in the center of the upper die 32 and the lower die 34,
The billet 35 is vertically clamped by the guide members 38 and 40 inserted in 34a.

Next, after inserting the upper forging punch 42 and the lower forging punch 44 into the hollow portions of the guide members 38, 40, the upper forging punch 42 and the lower forging punch 44 are press-fitted in the vertical direction to perform the closed forging. To do. As a result of this closed forging, as shown in FIG. 3, the billet 35 has the recesses 54a and 54b corresponding to the shapes of the tips 48 of the upper forging punch 42 and the lower forging punch 44, and the roller shafts 16a to 16c.
To form the intermediate body 56.

In this case, in the closed forging step, depending on the shapes of the tip portions 48 of the upper forging punch 42 and the lower forging punch 44, the central portion is a curved surface having a large diameter R and the peripheral portion is a small diameter r. Since the curved concave portions 54a and 54b are formed, the intermediate body 56 having a depth and a diameter effective for forming the shaft hole 12 can be obtained without cracks on the inner surface.

Next, from the intermediate body 56 to the upper forging punch 4
After the 2 and the lower forging punch 44 are respectively removed, as shown in FIG. 5, the punching punch 58 is press-fitted into the recesses 54a and 54b to remove the material between the recesses 54a and 54b. A shaft hole 12 having a diameter of 5/6 times the diameter D of the upper forged punch 42 and the lower forged punch 44 was formed.

Here, the recesses 54a and 54b are formed in the shaft hole 12
Has a depth and diameter effective for drilling, and is formed sufficiently thin. Further, as shown in FIG. 5, the corner portion 58a of the punching punch 58 has the concave portions 54a and 54b.
The material that comes into contact with the inner surface of the punch and moves from the A position to the B position comes into contact with the corner portion 58a in the space between the punch punch 58 and the large-diameter central portions of the recesses 54a and 54b. Since it flows, the initial resistance during punching becomes small. Therefore, in the process of punching, the load required for punching can be reduced, so that the occurrence of cracks in the material can be avoided and the shaft hole 12 in a suitable state can be obtained.

[0020]

According to the shaft hole forming method of the present invention,
A large diameter shaft hole is formed by closed forging using a forged punch in which the center of the punch tip is a curved surface with a large radius and the peripheral edge of the punch tip is a curved surface with a radius smaller than the central portion. It is possible to form a recess having a depth and a diameter effective for drilling without cracking. Then, by punching out this recess, a large-diameter shaft hole can be formed without causing deformation in the molded product.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a closed forging device according to the present invention.

FIG. 2 is an explanatory view showing the shape of the tip of a forging punch of the closed forging device according to the present invention.

FIG. 3 is a partial vertical cross-sectional view showing a forging process by the closed forging device shown in FIG.

FIG. 4 is a vertical cross-sectional view of an intermediate body of a constant velocity joint spider formed by using the closed forging device according to the present invention.

FIG. 5 is a partial vertical cross-sectional view showing a punching process.

6 is a vertical sectional view of a spider for a constant velocity joint obtained by punching out the intermediate body shown in FIG.

FIG. 7 is a plan view of a constant velocity joint spider formed by the closed forging device according to the present invention.

FIG. 8 is a vertical cross-sectional view of an intermediate body of a spider for a constant velocity joint obtained in a conventional technique.

[Explanation of symbols]

 10 ... Spider for constant velocity joint 12 ... Shaft hole 14 ... Boss portions 16a to 16c ... Roller shaft 30 ... Closure forging device 32 ... Upper die 34 ... Lower die 35 ... Billet 36 ... Space portion 38, 40 ... Guide member 42 ... Upper Forged punch 44 ... Lower forged punch 48 ... Tip portion 50 ... Central curved surface portion 52 ... Peripheral curved surface portion 56 ... Intermediate body 58 ... Punch punch

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-1-104437 (JP, A) JP-A-50-157251 (JP, A) JP-A-59-133927 (JP, A) JP-A-63- 20137 (JP, A) JP-A-1-104438 (JP, A) JP-A-3-268838 (JP, A) JP-A-59-147732 (JP, A) JP-A-1-215427 (JP, A) Japanese Examined Sho 46-32730 (JP, B2)

Claims (1)

(57) [Claims] 1. A closed forging device for forming a recess by press-fitting a punch into both end surfaces of a billet held by a die at positions corresponding to the shaft hole prior to punching the shaft hole. A closed forging device characterized in that a central portion is a curved surface having a large radius and a peripheral portion of the tip is a curved surface having a smaller radius than the central portion.