JPS6230056B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a hollow ball having a concave portion on the outer peripheral surface by press forming from a cylindrical material tube.

Conventionally, methods for forming this type of hollow ball include cutting methods and casting methods. However, in the cutting method, Fig. 1a,
As shown in b and c, a bar with a circular cross section is cut into appropriate dimensions (a in the figure), the outside is machined (b in the figure), and the inside is machined (c in the figure). However, since there are many parts to be shaved, material is wasted, the machining time becomes long, and the process becomes expensive, which is not desirable in terms of resource conservation, and the weight of the hollow ball is also heavy. In addition, in the casting method, as shown in Fig. 2 a, b, and c, molten material 2 is poured into a mold 1 (a in the same figure), and after it hardens, it is taken out from the mold (b in the same figure).
The removed material was machined and finished, as shown in figure c.However, with this method of casting, cavities are likely to form due to gas bubbles, so it was discovered after machining. There are many cases where the products are defective, resulting in a great deal of waste. In addition, due to the flow of the metal, the wall thickness becomes larger than necessary, which results in wasted material, and the weight also increases.Furthermore, the machined surface is rough, so a large amount of machining allowance is required, which increases the machining time. be.

In order to overcome the drawbacks of these cutting methods and casting methods, there is a method of making a hollow ball from a cylindrical material tube by press forming, which is shown in Figure 3 a, b, and c. First, pipe material is cut into appropriate dimensions to make a cylindrical material tube (see figure a), and this material tube is press-formed into a spherical shape using a press that has hemispherical concave portions in the upper and lower molds, respectively. (b in the same figure), and a recess 3 is formed on the outer peripheral surface by press molding (c in the same figure), and this recess 3 is used as a fitting part for a stem etc. for rotating the hollow ball. In this case, since the recess 3 can be formed only relatively shallowly, the contact area becomes small, the recess 3 quickly settles, and the durability is poor.

This invention was made in view of the above-mentioned circumstances, and its purpose is to first form a recess on the outer periphery of a cylindrical material tube by press working, and after inserting a space member into the recess. The material tube is formed into a spherical shape using a mold press, in which hemispherical recesses are formed in the upper and lower molds facing each other.Finally, by removing the space member, conventional mechanical cutting, casting, and press processing can be performed. The object of the present invention is to provide a method for molding a hollow ball having a concave portion on the outer circumferential surface, which eliminates all of the above-mentioned drawbacks.

The present invention will be described in detail below based on the accompanying drawings.

FIGS. 4a to 4e are process schematic diagrams showing the method according to the present invention. First, in FIG. The lower mold is divided left and right into a lower left mold 13 and a lower right mold 14, which can move forward and backward relative to each other in the horizontal direction (indicated by arrow A), and form a recess 12. It is inserted into a mold press 16 having a receiving recess 15. Next, as shown in FIG. 1B, the material tube 10 is pressed by the upper mold 11 and the left and right lower molds 13, 14 to form the recess 12 described above. Then, as shown in FIG.
The cylindrical axis of the material tube 10 is inserted into the mold press 22, which has hemispherical recesses 20 and 21 formed in the upper mold 18 and the lower mold 19 so as to face each other. Insert the tube 10 made of the same material so that it is in the vertical direction. Next, the material tube 10 is formed into a spherical shape by the pressing force of both the upper and lower molds 18 and 19 of the mold press 22. Finally, remove the space member 17 from the recess 12 and
A hollow ball having a recess 12 on the outer peripheral surface shown in FIG.

As described above, according to the present invention, in the method of manufacturing a hollow ball with a concave portion by press molding from a cylindrical material tube, (a) a concave portion is formed on the outer circumferential surface of the cylindrical material tube by pressing before forming into a spherical shape. (b) While inserting a space member into the recess,
The material tube is pressed in the direction of the cylinder axis to form a spherical shape. When a concave portion is formed on the outer surface by press molding after spherical molding, the concave portion cannot be made deep, as explained in relation to Fig. 3, and the concave portion is used as a locking groove for a stem, etc. In this case, there is a problem that the concave portion settles rapidly. However, in this invention, a deep recess is formed by (a) before spherical molding, and this recess is prevented from being deformed during spherical molding by (b), so that the deep recess is finally formed. It is possible to make hollow balls with In this way, both spherical molding and concave molding,
Since it is performed by press molding, the molding time can be shortened and costs can be reduced.

Furthermore, the surface texture is clean and finishing allowance is small, resulting in a uniform product and improved precision. In addition, the wall thickness can be reduced,
There is no waste of materials. Furthermore, unlike casting, there are no cavities, and the quality can be improved, so its utility value is remarkable.

[Brief explanation of the drawing]

Figure 1 a to c, Figure 2 a to c and Figure 3 a
Figures 4a to 4c are process schematic diagrams showing conventional methods using mechanical cutting, casting, and press working, and Figures 4a to 4e are process schematic diagrams showing the method according to the present invention. ,1
7... Space member, 18, 19... Both upper and lower types, 2
0, 21...Semispherical recess, 22...Mold press.

Claims (1)

[Claims] 1 A recess is formed on the outer peripheral surface of a cylindrical material tube by press molding, and the material tube with the recess formed therein has hemispherical recesses facing each other in the upper mold and the lower mold. The tube is inserted into both hemispherical recesses with the cylinder axis facing up and down, and
A space member capable of maintaining the shape of the recess is inserted into the recess on the outer circumferential surface of the material tube, and then the inserted material tube is processed into a spherical shape by the pressing force of both molds; A method for molding a hollow ball having a concave portion on an outer circumferential surface, characterized in that the space member is removed after the space member is removed.