JPH11290482A - Golf ball forming metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the releasability with a molded golf ball or molding intermediate product and extend the maintenance inspection period by setting the average surface roughness of the inner surface of a cavity to a specified range in a golf ball forming metal mold having upper and lower dies having semispherical recessed cavities. SOLUTION: A metal mold for forming a cover around a core by injection molding as a golf ball forming metal mold is formed of an upper die 1 having a semispherical recessed cavity 11 and a lower die 2 having a semispherical recessed cavity 12, and small projections 3 and so forth for dimple formation are arranged on the inner surface of each cavity 11, 12. The average surface roughness of the inner surface of the cavity and the inner surface of a material passage 13 is set within the range of 5 μm-60 μm. By setting the surface roughness to 5 μm-60 μm, a clearance (air layer) can be formed between the inner surface of the cavities 11 and 12 or the inner surface of the material passage 13 and the ball after molding to facilitate the releasing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball molding die.

[0002]

2. Description of the Related Art Conventionally, a molding die used for covering a core with a single-layer or plural-layer cover or a molding die used for molding the core itself has a cavity having a hemispherical concave shape. A mold and a lower mold were provided, and molding was performed by injecting or injecting or compressing a material into the cavity. The inner surface of a cavity and a material flow passage (runner) of a conventional molding die have been mirror-finished by minimizing the surface roughness.

[0003]

However, a golf ball material containing a metal salt of an unsaturated carboxylic acid such as zinc acrylate adheres to a molding die and has extremely poor releasability (demolding). Had reduced productivity. In addition, it is necessary to perform maintenance of the molding die in a short period.

[0004] The present invention solves such problems,
It is an object of the present invention to provide a golf ball molding die which has good releasability from a molded golf ball or molded intermediate product, improves productivity, and can extend a maintenance and inspection cycle.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a golf ball mold having an upper mold and a lower mold having a hemispherical concave cavity, wherein the average surface roughness of the inner surface of the cavity is 5 μm or less. It is 60 μm.

Further, in a golf ball molding die having an upper die and a lower die having a hemispherical concave cavity and a material flow passage communicating with the cavity, an inner surface of the cavity and / or the material flow passage is formed. Average surface roughness is 5 μm to 60
μm.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the illustrated embodiments.

In the cross-sectional front view of FIG. 1 and the simplified plan view of the main part of FIG. 2, a mold for forming a cover around the core C by injection molding as a golf ball molding mold. Is exemplified.

That is, 1 is an upper mold having a hemispherical concave cavity 11, and 2 is a lower mold having a hemispherical concave cavity 12. The two cavities 11, 12 are combined to form a spherical shape of the outer shape of a golf ball. Dimensions and shapes are set as possible, and small projections 3 for forming dimples are arranged on the inner surfaces of the cavities 11 and 12.

More specifically, an upper plate 5 having through holes 4
The block 6 having the cavity 11 is fitted into the through hole 4, and the lower plate 8 having the through hole 7 is fitted with the cavity 6.
The block 9 having the upper and lower cavities 11 and
12 are opposed to each other to form a spherical cavity space.

Reference numeral 13 denotes a material flow passage for sending the molten material of the cover of the golf ball to the cavity space.
This material flow passage 13 is a weir (ingate) 14 radially disposed (recessed) from the outer peripheral edge of the mating surface of the cavities 11 and 12.
And an annular runner connecting the outer ends of the weirs 14 ...
r) Consists of 15 etc.

Are holding pins for holding the core C at the center of the cavity space. The holding pins are reciprocally movable in the direction of arrow A and are inserted through insertion holes communicating with the cavities 11 and 12.

Although the material flow passage 13 is illustrated in FIG. 1 as an example in which grooves formed in both the upper mold 1 and the lower mold 2 are formed together, either the upper mold 1 or the lower mold 2 may be used. Only one of them may be provided, or a part may be formed in the upper mold 1 and the remaining part may be formed in the lower mold 2 (not shown).

Thus, in the golf ball molding die according to the present invention, the average surface roughness of the inner surface of the cavity 11 and the inner surface of the material flow passage 13 is set to 5 μm to 60 μm. Alternatively, the average surface roughness of either the inner surface of the cavity 11 or the material flow passage 13 is set to 5 μm to 60 μm.

By the way, as shown in FIG. 1, after the core C is put into the cavity space in advance, the upper die 1 and the lower die 2
Is closed, and while the core C is centered with the holding pins 16, a single synthetic resin such as an ionomer resin, a polyester elastomer, a polyurethane elastomer, and a polyamide elastomer, or a mixture of plural kinds thereof is mixed through the material flow passage 13. The molten material is supplied from an injection molding machine. As soon as the molten material is filled into the cavity, the pins 16 are retracted, and the cover is formed on the core C.

If cooled to some extent, the molded golf ball and the solidified material (runner) in material flow passage 13
Must be separated from the upper mold 1 and the lower mold 2 which are open to each other, but can be easily separated from the cavities 11 and 12 and / or the material flow passage 13 having a surface roughness of 5 μm to 60 μm as described above. , Can be released.

In the present invention, the "average surface roughness" is an average value of arithmetic average roughness (Ra) measured by a roughness meter in parallel with a mold at intervals of 10 mm. The roughness is measured using, for example, Surfcom570 of Tokyo Seimitsu Co., Ltd.

If the average surface roughness is less than 5 μm,
The releasability is the same as the conventional mirror surface without roughness.
It is the same as a conventional mold having a cavity having an inner surface (poor).

Conversely, when the average surface roughness exceeds 60 μm,
In the outermost cavities 11 and 12, small dimples 3
Are provided, and even if the molded golf ball is painted and finished, the surface is rough and unfavorable in appearance (as a final ball).

As described above, in order to obtain a surface roughness of 5 μm to 60 μm, blasting is suitable. For example, glass beads, steel balls and diamonds having a diameter of 0.2 to 2.0 mm are crushed with an air pressure of 1 to 20 kg / Processing is possible under shot blast conditions such as spraying with cm ² .

In the present invention, by setting the surface roughness to 5 μm to 60 μm in this way, the gap between the inner surfaces of the cavities 11 and 12 and the inner surface of the material flow passage 13 and the ball (or ball intermediate product) after molding is obtained. It is considered that a gap (air layer) is formed to facilitate release (release).

It is more preferable that the average surface roughness is 10 μm to 50 μm. In addition, the present invention is not limited to the above-described illustrated embodiment, and may be freely changed in design, for example, may be applied to a molding die used in a compression molding method. Material flow passage
13 corresponds to a burr protruding groove, a spew groove or the like from which an extra material is extruded during compression molding. In addition, core C
It is also preferable to apply it to a mold for molding itself.

[0023]

EXAMPLE In order to cover a core C for a solid two-piece golf ball with a cover (ionomer resin), as shown in the following Table 1, cavities 11 and 12 having a hemispherical concave shape and a material flow passage 13 were blasted. Average surface roughness of 5 μm
(Example 1) Continuous injection molding was performed using a mold having a thickness of 25 µm (Example 2), a thickness of 50 µm (Example 3), and a mold having a thickness of 75 µm (Comparative Example 2). The cavity 11 and the material flow passage 13 are mirror-finished to have an average surface roughness of 0 μm.
Was made as Comparative Example 1 and continuously injection-molded.

The following Table 1 shows the above-mentioned "average surface roughness",
"Releasability" and "Final ball appearance" corresponding to it
Is shown. "Releasability" is represented by an index. In the conventional comparative example, the number of moldings (life) until the release becomes difficult is 100 times.
And In the “final ball appearance”, “○” indicates that roughness was not conspicuous on the ball surface, and “×”
Indicates that the roughness of the ball surface is large and the appearance is poor.

[0025]

[Table 1]

From Table 1 above, the surface roughness of the mold was set to 0
It can be seen that the releasability is improved by making the roughness larger than μm (mirror surface).

[0027]

According to the present invention, the following significant effects can be obtained by the above-described structure.

The releasability of the molded golf ball or its intermediate product from the upper mold 1 and the lower mold 2 can be remarkably improved, and the productivity of the golf ball is improved. Moreover, the appearance of the molded final ball is also good.

[Brief description of the drawings]

FIG. 1 is a sectional front view showing an embodiment of the present invention.

FIG. 2 is a simplified plan view for explaining a main part configuration.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 11 Cavity 12 Cavity 13 Material flow passage

Claims (2)

[Claims] In a golf ball mold having upper and lower dies having hemispherical concave cavities, an average surface roughness of the inner surfaces of the cavities is 5 μm to 60 μm.
A golf ball molding die having a diameter of μm. 2. A golf ball molding die having upper and lower dies 1 and 2 having hemispherical concave cavities 11 and 12 and material flow passages 13 communicating with the cavities 11 and 12. A golf ball molding die, wherein the average surface roughness of the inner surface of the material flow path 11 and / or the material flow path 13 is 5 μm to 60 μm.