JPS61289930A - Forming method for hollow spherical item - Google Patents

Abstract

PURPOSE:To enable the forming with high efficiency without causing any buckling by squeezing the opening part of a blank with its forging with driving with turning by holding the boss part of a cup shaped blank and then by finishing it. CONSTITUTION:The boss part 31 of a cup shaped blank 3 is held by the knockout 43 provided on the lower die 42 of a rotary forging machine 4. The blank 3 is subjected to a rolling reduction with rotating the upper die 41 around the slant shaft by rotatively driving the cup shaped blank 3 around its center shaft. With this movement a hollow spherical body 5 is formed by subjecting to the squeezing by forging on the opening part 32 of the blank 3. Finally the squeezing part 51 and boss part 52 are finished by machining. A thin product can thus be formed with good yield.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method for forming a hollow spherical part from a bossed cup-shaped material by rotary forging.

(b) Prior Art Hollow spherical articles are used in high-pressure containers, mechanical joints, and the like. Conventionally, to manufacture this type of article, a block-shaped material was machined and shaped using a machine tool. This forming method has a very poor yield, the metal flow is not continuous, the strength is low, and cutting takes time.

Therefore, as shown in FIG. 4(A), a disk-shaped billet material is made into a cup-shaped molded body 1 by backward extrusion processing, and a fourth
As shown in Figure (B), a hollow spherical body 2 is produced by drawing the end of the cup-shaped molded body 1 by press working. The product obtained in this way has high strength and
It has the advantage of being able to be produced with high yield and high efficiency.

However, during press working, buckling is likely to occur in the drawing part (FIG. 4(B)), making it impossible to form a thin-walled product. Furthermore, if the cup-shaped molded body is thick, processing wrinkles will occur on the inner surface of the hollow spherical body (FIG. 4(C)).

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to provide a method for molding hollow spherical articles with high yield and high efficiency without causing material buckling during the molding process. It's about getting.

B) Means for Solving the Problems The method for molding a hollow spherical article of the present invention includes preparing a cup-shaped material having a boss portion at the bottom and an opening portion at the top; gripping and rotating forging around the central axis of the material, performing a mouth drawing process on the opening portion of the cup-shaped material to form a hollow spherical body with a boss portion; the boss portion of the hollow spherical body; And by finishing the mouth drawing part by machining,
The above problems have been resolved.

(E) Example A method for molding a hollow spherical article of the present invention will be described with reference to FIGS. 1(A) to 1(D).

The method of the present invention uses a cup-shaped material 3 (Figure (A)) as a starting material. The cup-shaped material 3 has a boss portion 31 at the bottom and an opening portion 32 at the top. The cup-shaped material 3 is formed by casting or pressing.

(B) As shown in the figure, the cup-shaped material 3 is cut into a rotary forging machine 4.
It is installed between the upper mold 41 and the lower mold 42.

A knockout 43 is provided in the center of the lower die 42;
The boss portion 31 of the cup-shaped material 3 is grasped at the top of the cup-shaped material 3, and the cup-shaped material 3 is rotated around its central axis. The cup-shaped material 3 rotates together with the lower die 42, the lower die support block 44, and the knockout 43. At the same time, as shown in the figure, with the central axis of the upper mold 41 tilted by an angle θ with respect to the central axis of the lower mold 42, the upper mold 41 rotates around the tilt axis and moves the material in the direction of the central axis of the lower mold. Press down.

Due to this movement, the opening portion 32 of the cup-shaped material 3 is subjected to a drawing process (see (C)), and the hollow spherical body 5 is formed.

Finally, the hollow spherical body 5 has a mouth opening part 5 according to the purpose of use.
1 and the boss portion 52, etc., are subjected to necessary machining and finished (Fig. D). In this way, the bossed hollow spherical article 6 is produced.

An example of the dimensions of the hollow spherical article 6 is shown in FIG. 1). The outer diameter of the article 6 is D1, the wall thickness is t1, and the inner diameter of the upper opening is d.

(F) Effect In the forming method of the present invention, as shown in FIG. 2, buckling is unlikely to occur in the upper part of the material during rotary forging. Unlike press forming, in rotary forging, the upper die 41 does not contact the entire circumference of the top of the material at the same time, but only partially, so even if the material tries to buckle in one direction (Figure (A)), the upper die 41 The part that is not in contact with the contact part 33NC) supports the contact part 33NC), and even if some buckling occurs, when the contact part 33 moves 180 degrees from there, it acts to correct the buckling that occurred previously. (
(B) Figure). In this way, the buckling limit is improved by rotary forging.

It is preferable that the cup-shaped material is designed taking into account the increase in thickness after the mouth is drawn. The boss portion 31 provided at the bottom of the cup-shaped material 3 is for preventing the material 3 from falling during rotary forging.

The cup-shaped material 3 is preferably heated to a predetermined temperature for ease of processing. Partial heating may be possible depending on the material of the material and the amount of processing. FIG. 3 shows the method of the present invention and the conventional method ( Shows the rate of mouth squeezing by press-based mouth squeezing method). Symbol ri, d.

Regarding t, the dimensions of each part are the same as shown in FIG. 1(D). It can be seen that according to the method of the present invention, the opening rate is significantly improved.

(G) Effects According to the present invention, buckling is less likely to occur, making it possible to form thin-walled products.Also, since most of the material is formed through the rotary forging process, yields are greatly improved, and metal・The flow becomes continuous, further improving strength, reducing processing time, and making it possible to mold even difficult-to-process materials.

[Brief explanation of drawings]

FIGS. 1A to 1D are explanatory diagrams showing steps of the method of the present invention. FIG. 2 is an explanatory diagram showing the operation of the method of the present invention. FIG. 3 is a graph showing the effect of the method of the present invention. FIG. 4 is an explanatory diagram showing a part of the process of the conventional method. 3: Cup-shaped material 5: Hollow spherical body 6: Hollow spherical article%

Claims (1)

[Claims] preparing a cup-shaped material having a boss portion at the bottom and an opening portion at the top; gripping the boss portion of the cup-shaped material and rotating it around the central axis of the material;
A hollow spherical article comprising: performing a mouth drawing process on the opening part of the cup-shaped material by rotary forging to form a hollow spherical body with a boss part, and finishing the boss part and the mouth drawing part of the hollow spherical body by machining. molding method.