JPH10314343A - Manufacture of golf ball and mold for preliminary molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly decrease eccentricity in an inner layer without damaging workability, in the manufacturing method for a multilayer golf ball. SOLUTION: In the manufacturing method, a semispherical unvulcanized outer layer half is molded in a preliminary molding mold 1 equipped with the first mold having a semispherical projecting portion 4 and a pair of the second molds 7 wherein an inner core supporting portion 9 is projected in at least one recessed portion 6. After that, a vulcanized inner core 2 is injected into the outer layer half in one of the second mold 7. After that, preliminary molding is formed by facing the second mold pair 7 to each other, bringing them closer to each other, and compressing them and by superposing a pair of outer layer halves on each other in a faced condition while holding the inner core in the center by the inner core supporting portion 9 of the recessed portion 6. After that, the preliminary molding is vulcanized and molded by a vulcanizing mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a golf ball, and more particularly to a method of manufacturing a golf ball having a multilayer structure, and a preforming die for forming a preformed product of the golf ball.

[0002]

2. Description of the Related Art Conventionally, there have been the following methods for producing a golf ball having a multilayer structure. In order to avoid eccentricity, when providing a certain layer, the inner part, that is, the inner core is separately vulcanized and then fixed at a predetermined position in the outer layer mold with a movable hold pin or the like,
A method of injecting a material for forming an outer layer with an injection molding machine or a transfer mold, pulling out a hold pin at an appropriate timing, and vulcanizing and molding as it is. The outer layer is semi-vulcanized in a semi-shell shape using a hemispherical concave shape and a hemispherical convex shape, or is heated in a non-vulcanized state for a certain period of time so as not to shrink, and then formed into a semi-shell shape. After removing, a vulcanization press molding is performed by setting a vulcanized inner core while keeping the semi-shell outer layer in a hemispherical concave shape (so-called core method). In the above method, a method in which the outer layer is formed in a sheet shape without forming a half shell shape. When forming one layer, it is a mold that is different from the mold that is vulcanized to the desired shape, and wraps the vulcanized layer inside it in an unvulcanized state in a floating state. Pre-molding method. A method in which a projection having the same length as the thickness of the outer layer is provided on the outer periphery of the inner core by integral molding, and the outer layer is covered with a quasi-spherical shell structure.

[0003]

However, the above method is not suitable for producing a golf ball having a multilayer structure. That is, in the above-described method, the entire structure of the mold apparatus is extremely complicated, and the number of presses per press is reduced due to the pressure limit at the time of material injection, which is not suitable for mass production. . Also, it has been difficult to set the diameter of the mold hole through which the movable pin is inserted. That is, if the clearance between the outer peripheral surface of the movable pin and the inner peripheral surface of the mold hole is extremely small, reciprocation of the movable pin cannot be performed smoothly. Conversely, if the clearance is large,
This is because rubber may flow out of the clearance.

[0004] In addition, although the above-mentioned method overcomes the problem of a small number of presses in one press and the problem of a mold hole, once the outer layer is formed in a half-shell shape, the half-shell is formed. Although the outer layer needs to adhere to the half-shell concave shape, it mostly adheres to the half-shell convex shape and needs to be transferred to the half-shell concave shape. could not. Further, the above-described method has the same drawback as the above-described method, except that the preparation of the outer layer half body is changed to a sheet shape.

Further, since the above-described method includes a molding step in an unvulcanized state, the vulcanized inner layer is eccentric, and once formed, uneven shrinkage due to eccentricity occurs.
Peeling, or so-called opening, occurred from the two bonded portions, resulting in eccentricity and reduced workability after vulcanization. In order to prevent this, it is necessary to finely adjust the pressing time and pressure according to the change of the rubber material, but this is not a sufficient measure, and it is necessary to absorb variations in the previous process and rubber material. I didn't get it. In addition, it is possible to enhance the adhesive strength by using an adhesive, but this increases the number of steps and also causes variation. In the method (1), the theoretical eccentricity can be reduced to zero, but the protrusion integrally formed on the inner core has poor peelability from the mold. In order to cope with this, it is conceivable to form the projection by shaping after forming with the outer layer diameter, but it is extremely troublesome and not realistic.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a golf ball capable of remarkably reducing the amount of eccentricity without deteriorating workability and capable of mass-producing a high quality golf ball having a multilayer structure. It is another object of the present invention to provide a preforming die capable of significantly reducing the amount of eccentricity of the inner core during preforming.

[0007]

In order to achieve the above-mentioned object, a method of manufacturing a golf ball according to the present invention comprises a first mold having a hemispherical projection and a hemispherical recess having at least one of After forming a half-shell-shaped unvulcanized outer layer half using a preforming mold having a pair of second dies having an inner core supporting portion protruding from the concave portion, one of the second dies is formed. The vulcanized inner core is put into the outer layer half body in the mold, and then the pair of second dies are pressed against each other so as to face each other, and the inner core is held at the center by the inner core support portion of the concave portion. In addition, a pair of the outer layer halves are superposed on each other to form a preform, and then the preform is vulcanized by a vulcanization mold.

The preforming die according to the present invention is a preforming die for wrapping a vulcanized inner core with an unvulcanized outer layer to form a preform of a golf ball having a multilayer structure. A first mold having a hemispherical convex portion and a pair of second molds having a hemispherical concave portion are provided, and the vulcanized inner core is held at the center of the concave portion in the concave portion of at least one of the second types. The inner core support part to be protruded. It is preferable that at least three inner core support portions are formed in the recess.
Further, it is desirable that the inner core supporting portion is formed in a flake shape having an arc-shaped abutting edge along the outer peripheral surface of the vulcanized inner core.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3, FIG. 4, and FIG. 5 schematically show a method of manufacturing a golf ball according to the present invention, and a preforming mold having a cavity of a different shape from the cavity of a vulcanizing mold (not shown). At 1, a vulcanized inner core 2 is wrapped with an unvulcanized outer layer 3 to form a multi-layer golf ball preform S.
Thereafter, the preformed product S is vulcanized and molded by a vulcanizing mold (not shown) to produce a product (a golf ball having a multilayer structure).

The preforming mold 1 includes a first mold 5 having a hemispherical convex portion 4 and a pair of second molds 7 having a hemispherical concave portion 6. Thus, as shown in FIG. 1, FIG. 2, and FIG. 6, the half shell-shaped cavity 8 is formed by the first and second dies 5, 7. Further, inner core supporting portions 9 for holding the vulcanized inner core 2 at the center of the concave portions 6 and 6 are protruded from the concave portions 6 and 6 of the pair of second dies 7 and 7. Specifically, in the recess 6,
4 small radial grooves at 90 ° pitch when viewed from the opening direction
Are formed, and the flaky inner core support portions 9 are fitted into and fixed to the small groove portions 10. Further, the inner core supporting portion 9 is formed in a flake shape having an arc-shaped abutting edge 11 along the outer peripheral surface of the vulcanized inner core 2.

More specifically, the second dies 7, 7
Is a mold body 12, and a slide body fitted to the mold body 12.
13 is provided. The mold body 12 has a large diameter portion 14a and a small diameter portion 14b.
Is formed, and a small diameter portion 14b of the hole 14 is formed.
In addition, a slide body 13 having a concave surface 15 formed at the upper end is slidably fitted. Then, the large diameter portion 14a of the mold body 12
Then, the concave portion 6 is constituted by the concave surface 15 of the slide body 13.

The inner surface of the concave portion 6 of the second mold 7, 7 (specifically, the inner surface of the large diameter portion 14a of the mold body 12) has a circumferential groove.
16, 16 are formed. Further, as shown in FIG. 1, the radius of curvature b of the arc of the contact end edge 11 of the inner core supporting portion 9 of the second mold 7, 7 is substantially the same as the radius c of the vulcanized inner core 2 shown by a virtual line. And is set slightly larger than the radius of curvature a of the convex portion 4 of the first mold 5. Then, the inner core support portion 9
When the first mold 5 is superimposed on the molds 7, 7, the contact edge 11 is
And at the center of the concave portions 6, 6 facing each other so that the vulcanized inner core 2 is not displaced in the horizontal direction or the vertical direction during the pressure molding (preliminary molding) shown in FIG. It is formed so that it can be held.

Further, as shown in FIG.
Is set to 0.2 to 2.0 mm. This is because if the thickness T is less than 0.2 mm, the strength of the inner core supporting portion 9 is insufficient at the time of pressure molding, and the inner core 2 cannot be held at the center. On the other hand, if the thickness T exceeds 2.0 mm, the groove formed in the preform S by the inner core supporting portion 9 becomes too large,
This is because air pools are generated during vulcanization molding.

Thus, the pair of second dies 7, 7 are (in FIG. 3 to FIG. 5) swing-driven by a folding device having a hinge mechanism H. Specifically, as shown in FIG. 3 (a), the open state in which the concave portions 6 of both the second molds 7, 7 face upward, and as shown in FIG. The second die 7 can be swung between an overlapping state in which the second die 7 is in an opposed state. In the illustrated example, the second molds 7 and 7 each have two concave portions 6.
Although each is provided, it is needless to say that the number is not limited to two, and the number can be freely increased or decreased. Further, an upper plate 17 and a lower plate 18 of a press device are disposed above the first die 5 and below the second dies 7, 7, and the upper plate 17 and the lower plate 18 are relatively moved by a driving mechanism (not shown). Can be approached and separated from

Next, a method of manufacturing a golf ball using the above-configured mold apparatus will be described. First, FIG.
As shown in (a), the second molds 7, 7 are in a horizontal open state (that is, the recesses 6 of the second molds 7, 7 are open upward), and each of the recesses 6 is After the material (raw rubber) R for forming the outer layer is charged, the first die 5 is arranged below the upper plate 17 of the pressing device as shown in FIG.
As shown in (c) of FIG.
Is pressed against the second molds 7, 7 at a predetermined pressure for a predetermined time to form a half-shell-shaped unvulcanized outer layer half body 20.

Thereafter, as shown in FIG.
17 and the first mold 5 are raised. At this time, the second mold 7, 7
Since the circumferential grooves 16, 16 are formed in the concave portion 6, a part of the outer layer half body 20 enters into the circumferential grooves 16, 16 to form a locking shape. (See FIG. 1). Thereafter, the first mold 5 is removed from the press device.

Next, as shown in FIG. 4A, the vulcanized inner core 2 is put into the outer half half body 20 of one of the second molds 7, and the vulcanized inner core 2 is put into one of the second molds 7. The other second mold 7 (the outer half half 20 is adhered to the other second mold 7) shown in FIG. 4 is rocked as shown in FIG. As shown in (c), they are superposed and pressed by the upper plate 17 and the lower plate 18 of the press device to form a preform S. That is, the preformed product S is formed by superposing the pair of outer half halves 20, 20 facing each other while holding the vulcanized inner core 2 at the center by the inner core support portions 9 of the concave portions 6, 6.

At this time, as shown in the enlarged sectional view of FIG. 6, the vulcanized inner core 2 is held at the center by the inner core support portions 9 of the concave portions 6, 6 of the second molds 7, 7. Thereby, the vulcanized inner core 2 can be reliably positioned at the center of the preformed product S (the center of the unvulcanized outer layer 3).

Thereafter, as shown in FIG. 4D, the second dies 7, 7 are opened, and as shown in FIG.
The slide body 13 is raised, and the preform S (unvulcanized golf ball) is removed from the second mold 7. Thereafter, the preformed product S is vulcanized and molded by a vulcanization molding die (not shown).
A golf ball (product) is formed by covering the cover. In the preform S, small grooves formed by the inner core supporting portions 9 are formed, but the small grooves completely disappear during vulcanization molding.

As described above, according to the golf ball manufacturing method and the preforming mold 1, the vulcanized inner core 2 is formed in the inner core supporting portions 9 of the concave portions 6, 6 of the second dies 7, 7. Can be positioned at the center of the preform S. Therefore, inner core 2
Can be significantly reduced.

Compared with the case where the inner core supporting portions 9 are not provided, as shown in FIG. 7A, the second molds e and f having the concave portions g and g without the inner core supporting portions are provided. To form the preform s, the uncured outer layer half h, h
The vulcanized inner core i floats between (raw rubbers) and is offset from the center, causing an offset. In this case, as shown in (b), non-uniform shrinkage after pressure molding occurs, and as shown in (c), the opening j opens in the outer layer k. In this case, the inner core i is cured by the vulcanization molding in the next step as shown in (d).
Would be greatly eccentric.

On the other hand, in the present invention, as shown in FIG. 6, the vulcanized inner core 2 can be surely positioned at the center of the preform S, so that the shrink of the outer layer 3 becomes uniform and the mouth is opened. And the eccentricity of the inner core 2 hardly occurs during vulcanization molding. Therefore, a golf ball having a high-quality multilayer structure can be manufactured. Further, the concave portion 6 of each of the second dies 7, 7 has an upper opening shape, so that material can be easily introduced into the concave portion 6,
And a mold for forming the outer layer half 20 and a pair of outer layer half
Since it can be used as a mold for preforming by superimposing 20, 20, the work efficiency is excellent.

Also, since the preform S can be pushed out by sliding the slide body 13 of the second molds 7, 7 toward the opening of the recess 6, even if the releasability is poor, the preform S
It can be easily and reliably taken out without applying excessive force to the device.

Next, FIG. 8 shows another embodiment of the preforming mold, in which the inner core support portions 9 of the second dies 7, 7 are rectangular, and each corner of the support portion 9 is formed. The parts 21 and 21 are configured to abut on the outer peripheral surface of the vulcanized inner core 2 indicated by the imaginary line and hold it at the center. Other configurations are the same as those in FIGS.

The preforming mold of the present invention can be designed and modified in addition to the above-described embodiment.
In some cases, the inner core support 9 may protrude only in one of the recesses 6 of the molds 7, 7. The shape of the inner core supporting portion 9 is preferably a thin rod shape other than the flake shape as described above. In this case, the outer diameter of the thin rod-shaped support portion 9 should be 0.2 to 0.2 mm.
Set to 2.0 mm. The reason for this is that if the outer diameter is less than 0.2 mm, the strength of the inner core supporting portion 9 is insufficient at the time of pressure molding, and the inner core 2 cannot be held at the center. If the outer diameter exceeds 2.0 mm, the preformed product S This is because the hole formed by the inner core supporting portion 9 is too large, and an air pool is generated during vulcanization molding. In addition, the inner core support portions 9 for each recess 6 ...
Is not limited to four, but three or five to eight.
In some cases, it may be good. If the number is less than three, the inner core 2 cannot be held at the center, and if the number is nine or more, an air pocket occurs at the time of vulcanization molding.

[0027]

EXAMPLES Next, preforming dies of Examples 1 and 2 and Comparative Example were produced. Example 1 is a mold similar to that shown in FIG. 8 in which the inner core support is rectangular flakes and receives the inner core at its corners, and Example 2 is an arcuate mold having the inner core support. A mold similar to that shown in FIG. 1 having a flaky shape with a tangential edge was used. In Comparative Example, a mold similar to that shown in FIG.

Then, each mold is pressurized at a pressure of 1 ton per cavity for 10 seconds to form an outer layer half,
Thereafter, the vulcanized inner core was put into the half body, the pair of second dies was combined, and each cavity was pressurized at a pressure of 2 tons for 10 seconds, and further vulcanized at 160 ° C. for 20 minutes. The rubber was compounded with 100 parts of BROI, 25 parts of zinc acrylate, 20 parts of zinc white, and 1 part of dicumyl peroxide. The results of this molding are shown in Table 1 below.

[0029]

[Table 1]

In Table 1 above, the eccentricity of the inner core was the average of 60 preformed products. As is clear from Table 1, the eccentricity of the inner core of the preforming molds of Examples 1 and 2 is significantly smaller than that of the comparative example. In particular, the eccentricity of the mold of the second embodiment, which receives the inner core at the arcuate contact edge, is smaller. From these results, it can be said that according to the golf ball manufacturing method and the preforming mold of the present invention, a high-quality multi-layered golf ball with extremely small eccentricity can be manufactured.

[0031]

Since the present invention is configured as described above, the following effects can be obtained.

According to the method of manufacturing a golf ball according to the first aspect, a high-quality multi-layer golf ball having an extremely small eccentricity of the inner layer can be mass-produced simply, reliably, and efficiently.

According to the preforming die according to the second aspect,
A preformed product in which the eccentricity of the vulcanized inner core 2 with respect to the unvulcanized outer layer 3 is extremely small can be formed. According to the preforming die according to the third aspect, the eccentricity of the vulcanized inner core 2 with respect to the unvulcanized outer layer 3 is significantly reduced. According to the preforming die according to the fourth aspect, the amount of eccentricity of the vulcanized inner core 2 with respect to the unvulcanized outer layer 3 can be further reduced.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a preforming mold according to the present invention.

FIG. 2 is a plan view of a main part.

FIG. 3 is an explanatory view of a method of manufacturing a golf ball according to the present invention.

FIG. 4 is an explanatory diagram of a method of manufacturing a golf ball.

FIG. 5 is an explanatory diagram of a method of manufacturing a golf ball.

FIG. 6 is an enlarged sectional view of a main part during preforming.

FIG. 7 is an explanatory diagram of a comparative example.

FIG. 8 is an enlarged sectional view of a main part of another embodiment of a preforming die.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 Preforming mold 2 Vulcanized inner core 3 Outer layer 4 Convex part 5 First die 6 Concave part 7 Second die 9 Inner core support part 11 Contact edge 20 Outer layer half body S Preformed product

Claims (4)

[Claims] 1. A pair of second molds 7, having a first mold 5 having a hemispherical convex portion 4 and a hemispherical concave portion 6 and having at least one of the concave portions 6 provided with an inner core supporting portion 9. After forming half shell-shaped unvulcanized outer layer halves 20, 20 in the preforming mold 1 provided with the above, the outer layer half 20 in one of the second molds 7 is formed. The vulcanized inner core 2 is charged, and then the pair of second dies 7, 7 are pressed against each other so as to be opposed to each other, and the inner core 2 is held at the center by the inner core support portions 9 of the concave portion 6. A pair of the outer half halves 20, 20 are superposed on each other to form a preform S, and thereafter, the preform S is vulcanized by a vulcanization mold. Golf ball manufacturing method. 2. A preforming mold for wrapping a vulcanized inner core 2 with an unvulcanized outer layer 3 to form a preformed product S of a multi-layered golf ball, having a hemispherical convex portion 4. First type 5
And a pair of second dies 7 and 7 having a hemispherical concave portion 6. An inner core holding the vulcanized inner core 2 in the center of the concave portion 6 in the concave portion 6 of at least one of the second dies 7. Support part 9
... a preforming mold characterized by projecting. 3. The preforming die according to claim 2, wherein the inner core supporting portion is formed in at least three places in the concave portion. 4. The preforming metal according to claim 2, wherein the inner core supporting portion is formed in a flake shape having an arc-shaped abutting edge along the outer peripheral surface of the vulcanized inner core. Type.