JPH0229320A - Manufacture of colored partly hollow rubber ball - Google Patents

Abstract

PURPOSE:To form clearly a boundary between a colored section and an uncolored section by heating a ball material inserted into a molding chamber of a second vulcanizing mold, bringing the surface of the ball material into close contact with the inner surface of the molding chamber, expanding a colored piece in a recess section in said state and bringing the same into close contact with the inner surface of the molding chamber. CONSTITUTION:A ball material 6 is inserted into a molding chamber 3 of a fist vulcanizing mold l and heated. The ball material 6 is molded into the globular shape with a recessed section 7 on the surface. A belt-shaped colored piece 8 made of unvulcanized rubber is buried in said recessed section 7. The ball material 6 is inserted into a mold chamber 4 of a second vulcanizing mold 2 and heated. The ball material 6 is expanded by heating because of the internal pressure rising, and the whole surface of the ball material 6 except the recessed section 7 is brought into close contact with the inner surface of molding chamber 4. A colored piece 8 in the recessed section 7 is expanded and brought into close contact with the inner surface of the molding chamber 4. Vulcanization reaction of the ball material 6 is restarted by said heating to start vulcanization reaction of the colored piece 8, and a hollow rubber ball (a) consisting of the ball material 6 bonded integrally with the colored piece 8 is prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to a method of manufacturing hollow rubber balls, such as partially colored soft-ball baseballs.

[Prior Art] Recently, hollow rubber balls such as softball baseball balls whose surfaces are partially colored have been provided.

For such hollow rubber balls, predetermined portions of the surface of the ball are colored by painting, or colored strips are pasted onto predetermined portions of the ball surface, and this coloring is done by heating the strip. The method used is to apply pressure while fixing the ball integrally to the surface of the ball.

[Problems to be Solved by the Invention] However, the method of providing colored portions by painting has the disadvantage that the ball wears out quickly as the ball is used, and the colored portions become unclear or easily disappear. be.

In addition, when a coloring strip is attached to the surface of the ball and the coloring is fixed by applying pressure while heating the coloring strip, the periphery of the coloring strip protrudes due to the pressure and the coloring is stopped. There is a problem that the boundary line between one part and another part becomes distorted or unclear, deteriorating the appearance. In particular, when a design is applied to the surface of the ball, it is almost difficult to clearly distinguish between the design and the coloring.

The present invention has been made with attention to these points, and it is possible to obtain a hollow rubber ball with a good appearance by clearly dividing the boundary between the colored part and the non-colored part without disturbance or distortion. The purpose of this invention is to provide a method for manufacturing hollow rubber balls that can be manufactured using the following methods.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a molding chamber in a first vulcanization mold in which a convex portion corresponding to the portion of the ball to be colored is provided on the inner surface. A ball element made of unvulcanized rubber is inserted into the inside of the ball element, the ball element is heated and expanded, and this expansion forms a recess corresponding to the convex part on the surface of the ball element. Before the vulcanization reaction of the body is completed, the ball body is taken out from the first vulcanization mold, and the recesses of the ball body are colored with a predetermined color, and the depth of the recesses is A colored piece made of unvulcanized rubber that is thinner than the mold is embedded, and then the ball cord body is inserted into the molding chamber of the second vulcanization mold and heated. This was followed by coloring by expanding each piece and allowing the vulcanization reaction to complete.

[Function] When the ball element inserted into the molding chamber of the second vulcanization mold is heated, the surface of the ball element first comes into close contact with the inner surface of the molding chamber, and in this state, the coloring in the recessed part is removed. The piece expands and adheres tightly to the inner surface of the molding chamber, so the periphery of the colored piece does not protrude to the surface of the ball body, and there is no difference between the colored part and the non-colored part. The border line is clearly formed without any disturbance or distortion.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

In Fig. 2, 1 is a first vulcanization mold, 2 is a second vulcanization mold, and these are E-types 1a, 2a and lower molds 1b, 2b.
The upper mold 1a is divided into two parts.

A spherical molding chamber 3.4 is formed inside each vulcanization mold 1.2 by joining 2a and the lower molds 1b, 2b. The inner surface of the molding chamber 3 in the first vulcanization mold 1 is integrally provided with, for example, a band-shaped convex portion 5 corresponding to the portion of the ball to be colored.

Reference numeral 6 shown in FIG. A chemical that generates a large amount of gas is sealed in advance.

Next, the process of manufacturing hollow rubber balls will be described.

First, as shown in FIG. 3, the ball body 6 is inserted into the molding chamber 3 of the first vulcanization mold 1. In this state, the ball body 6 is heated through the vulcanization mold 1 for a predetermined period of time. Due to this heating, the chemicals sealed inside the ball body 6 are decomposed and a large amount of gas is generated, and the ball body 6 expands due to the pressure of this gas and the thermal expansion of the rubber itself, and its outer surface is molded. The ball body 6 is in close contact with the inner surface of the chamber 3, and the vulcanization reaction of the rubber of the ball body 6 progresses as a result of this heating. However, before the vulcanization reaction is completed, the vulcanization mold 1 is cooled and stopped. Then, open the vulcanization mold 1 and release the ball body 6.
Take out.

The ball body 6 is shaped to correspond to the molding chamber 3, that is, as shown in FIG. Then,
The inside of the recess 7 is polished to remove foreign matter and dirt, and a band-shaped colored piece 8 made of unvulcanized rubber that has been colored in a predetermined color is embedded in the recess 7. This coloring is based on the thickness t of piece 8.
is slightly thinner than the depth h of the recess 7, for example, if the depth h of the recess 7 is 31111, as shown in FIG. Therefore, the coloring leaves a small space 9 between the surface of the piece 8 and the opening surface of the recess 7.

Thereafter, as shown in FIG. 6, the ball element 6 is inserted into the molding chamber 4 of the second vulcanization mold 2. And vulcanization mold 2
The ball body 6 is heated for a predetermined period of time. Due to this heating, the ball element 6 expands due to an increase in internal pressure, and the seventh
As shown in the figure, the entire surface of the ball body 6 except for the recess 7 is in close contact with the inner surface of the molding chamber 4. Thereafter, the colored piece 8 in the recess 7 expands to fill the space 9 and comes into close contact with the inner surface of the molding chamber 4. For this close contact, the ball element 6
This also contributes to the increase in internal pressure, and therefore coloring can be applied sufficiently even when a design of protrusions 8a is provided on the surface of the piece 8, as shown in FIG. Further, due to the heating at this time, the vulcanization reaction of the ball body 6 is restarted, and thereafter, the vulcanization reaction of the colored piece 8 is further started. After a while, the vulcanization reaction of the ball body 6 and the colored piece 8 is completed, and a hollow rubber ball a as shown in Figure 1 is formed in which the colored piece 8 is integrally combined with the ball body 6. Complete.

According to such a manufacturing process, when the surface of the ball body 6 is in close contact with the inner surface of the molding chamber 4, the coloring in the recess 7 is caused by the expansion of the piece 8, which is in close contact with the inner surface of the molding chamber 4. Therefore, the periphery of the colored piece 8 does not protrude to the surface side of the ball body 6, and the boundary line between the colored part and the non-colored part is clear and clear without disturbance or distortion. A hollow rubber ball a having a good appearance can be obtained. Since the colored piece 8 is embedded in the recess 7 and is integrally bonded to the ball body 6, the bonding strength is strong, and it is suitable for use with softball baseball balls that are hit hard, for example. Even in this case, since the colored piece 8 has a sufficient thickness, there is an advantage that loss due to wear can be almost permanently prevented.

[Effects of the Invention] As explained above, according to the present invention, the boundary line between the colored part and the non-colored part is clearly formed without disturbance or distortion, and a hollow rubber ball with a good appearance can be obtained. In addition, the coloring has the effect of firmly bonding the piece to the ball and almost permanently preventing it from disappearing due to wear.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a front view of a completed hollow rubber ball, FIG. 2 is a sectional view of the first and second vulcanization molds, and FIG. 3 is a cross-sectional view of the first vulcanization mold. A cross-sectional view of the ball body inserted into the vulcanization mold, Fig. 4 is a front view of the ball body after molding in the first vulcanization mold, and Fig. 5 is a cross-sectional view of the ball body inserted into the vulcanization mold. Figure 6 is a cross-sectional view of the ball body inserted into the second vulcanization mold.
FIG. 7 is a cross-sectional view showing a state in which the colored piece inside the recess is expanded, and FIG. 8 is a cross-sectional view showing a state in which a protrusion is provided as a design on the surface of the colored piece. 1... First vulcanization mold, 2... Second vulcanization mold, 3
．． 4...Molding chamber, 5...Convex portion, 6...Ball body, 7...Concave portion, 8...Coloring is one piece. Figure 1 Figure 2 Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (1)

[Claims] A ball body made of unvulcanized rubber is inserted into the molding chamber of a first vulcanization mold whose inner surface is provided with a convex portion corresponding to the portion of the ball to be colored, and this ball body is heated. This expansion forms a concave portion corresponding to the convex portion on the surface of the ball body, and before the vulcanization reaction of the ball body is completed, the ball body is placed in a first vulcanization mold. A colored piece made of unvulcanized rubber, which is colored in a predetermined color and whose thickness is thinner than the depth of the recess, is embedded in the recess of the ball element, and then the ball element is removed. is inserted into the molding chamber of the second vulcanization mold and heated, and this heating causes the ball body and subsequently the colored piece to expand and complete the vulcanization reaction. A method for manufacturing colored hollow rubber balls.