JPS59220343A - Preparation of sphere made of synthetic resin - Google Patents

Abstract

PURPOSE:To inexpensively obtain a sphere made of a synthetic resin having excellent appearance and strength, by a method wherein a ring body having three or more of protrusions formed to the outer periphery thereof is inlaid with a core sphere and the formed assembly is mounted in a mold while a molten resin is injected into the mold to form a skin layer on the surface of the core sphere. CONSTITUTION:An inlaying groove 22 is provided to the entire peripheral edge of the split surface 21 of one semi-spherical core 2 formed by splitting a sphere at the equator surface thereof into two halves and a ring body 3 having at least three protrusions 31 radially provided to the outer periphery in almost equal intervals is inlaid with said inlaying groove 22. Subsequently, the protrusion 12 and the recessed part 23 of the other semi-spherical core 1 and the recessed part 24 and the protrusion 23 of the semi-spherical core 2 are respectively inlaid to fabricate an integral core sphere 4 which is, in turn, subsequently mounted in a skin layer forming mold 5 and a molten resin is injected into the space 6 formed between the surface of the core sphere 4 and the molding surface of the skin layer forming mold 5 to mold a skin layer with a constant thickness. By this method, an objective sphere made of a synthetic resin is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing synthetic resin spheres. For K, which manufactures solid spheres made of synthetic resin by injection molding, a method has been developed in which an outer skin layer is formed by injection molding on the surface of a pre-molded core sphere. In order to provide a space between the mold surface and the mold surface in which the outer skin layer is injected, attempts have been made to use a core ball with protrusions on its surface.

However, if the core ball is provided with a protrusion, the tip of the protrusion will appear on the surface of the outer skin layer, that is, the surface of the sphere, so if the core ball and the protrusion are not the same color as the outer layer resin, the appearance of the sphere will be spoiled. In addition, if the materials of the protrusion and the outer skin layer resin are different, there is a disadvantage that the melt adhesion is poor and damage or peeling may occur due to impact from external forces or expansion and contraction due to temperature changes. There is also the inconvenience of having to use the same color and resin as N.

The present invention solves the above-mentioned conventional drawbacks, and the present invention is a synthetic resin that has a good appearance and no decrease in strength, without causing the color or material of the core to appear on the surface of the sphere, even if the color or material of the core sphere and the outer skin layer resin are different. The present invention aims to provide a method for manufacturing a spherical body.

Next, embodiments of the present invention will be described with reference to the drawings.

One hemisphere core 20 is shown in Fig. 1 and is angled by 2 minutes at the equatorial plane.
A fitting groove 22 is provided around the entire circumference of the dividing surface 210. 3 is a ring body of the same color and quality as the outer layer resin that will later be coated on the core ball, and has a size and shape that can be fitted into the fitting groove 22, and has a thickness of the outer layer resin that is coated on the outer periphery. Convex portions 31, 31, . . . having a length equal to , are provided radially at approximately equal intervals. Each dividing surface 11.21Vc of the hemispherical core 1.2 is provided with a protrusion 12.23 and a recess 13.24 that fit together.

During manufacturing, the fitting groove 22 of the hemispherical core 2! Fit the J-ring body 1. The protrusion 12 and recess 13 of one hemispherical core 1 and the recess 24 and protrusion 23 of the other hemispherical core 2 are fitted, respectively, to obtain an integrated core sphere 4.

Next, as shown in Figure 4jIJ2, when the core ball 4 is placed into the outer skin layer molding die 5 with the hemispherical core 2 fitted with the ring body 3 facing down, the protrusion 31 provided on the ring body 3 ,3
1...° is inscribed in the surface of the mold for forming the outer skin layer, and the core ball Fi is loaded in a suspended state on the inner surface of the mold by the convex portions 31, 31...K, and the surface of the core ball 4 and the outer surface of the core ball 4 are A mold cavity 6 for molding the outer skin layer is formed between the mold surface of the mold 5 for molding the skin layer.

After the mold is clamped, an outer skin layer resin is injected into the mold cavity 6 by injection molding, so that the outer skin layer is molded and coated with a constant thickness on the surface of the core sphere.

In addition, in the assembly example, the core ball was made by joining two hemispherical cores, but it is also possible to use a core ball that is integrated from the beginning. As a means of fitting and attaching, the ring body may be fitted to the core ball and then bonded with an adhesive.

However, if the ring body is fitted into the groove provided on the periphery of the split surface of one hemispherical core and then the two hemispherical cores are joined to form a core ball, as in the example above, the ring body can be inserted into the core. Can be firmly and easily attached to the ball.

In addition to joining the two hemispherical windows by fitting the projections and the four parts, a joining method using an adhesive may also be used.

According to the manufacturing method of the present invention, a ring body having a convex portion is fitted and attached to a core ball. As long as the core ball is made of the same color and material as the outer skin resin, the core ball may be made of a different material and color from the outer skin layer resin, and cheaper materials such as recycled resin or wooden method can be used, which is economical. For example, it is suitable for manufacturing balls for gateball games.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention, and FIG. 2 is a sectional view taken along the line n--■ in FIG. 1, showing one embodiment of the present invention. Patent applicant Sekisui Chemical Co., Ltd. Representative Mototoshi Hizunuma

Claims (1)

[Scope of Claims] L A core ball to which a ring body having three or more convex portions at approximately equal intervals on the outer circumference is fitted and attached is loaded into an injection mold, and the outer surface of the core and the mold are 1. A method for producing a synthetic resin sphere, which comprises injecting molten resin into a mold cavity for molding the outer skin layer formed between the core sphere and the outer skin layer to form an outer skin layer on the surface of the core sphere. 2. Two hemispherical cores in the shape of a core sphere divided approximately at the equator plane are joined together, and the ring body is fitted into a fitting groove provided on the periphery of the divided surface of one hemispherical core. A method for manufacturing a synthetic resin sphere according to claim 1.