JPH08322966A - Manufacture of golf ball - Google Patents

Abstract

PURPOSE: To effectively and certainly manufacture a high quality golf ball having no eccentricity. CONSTITUTION: A hemisphere of a core (d) is supported on a first base die 2a so that the core is held, and the other hemisphere of the core protruding from the first base die is covered with a first cover molding die 5a, and a cover layer 8a is injection-molded onto the hemisphere, and one hemisphere of the core provided with the cover layer is supported by a second base die 2b so that the core is held, and the other hemisphere of the core protruding from the second base die is covered with a second cover molding die 5b, and a cover layer 8b is injection-molded onto the other hemisphere, and thereby cover layers are formed on the surface of the core (d) in such an arrangement as hemisphere by hemisphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a golf ball by covering a core ball with a cover. More specifically, the cover is injection-molded on the surface of the core ball so that there is no eccentricity. The present invention relates to a golf ball manufacturing method for efficiently and reliably manufacturing a high quality golf ball.

[0002]

2. Description of the Related Art Conventionally, when a cover layer is injection-molded on the surface of a core ball to obtain a golf ball in which the core ball is covered with a cover,
A core ball is placed in a mold that is divided into two parts, and the core ball is supported by a support pin, and a cover material is injected into a cavity formed between the inner surface of the mold and the surface of the core ball to cover the core ball. The method of forming the layers is taken.

That is, as shown in FIG. 4, a core ball d is placed in a mold c composed of two mold halves a and b, and both mold halves a,
Runners formed on the mating surface (PL surface) of both mold halves a and b by holding the core sphere d at the center position in the mold c by support pins e provided in the vertical direction on b respectively. A cavity h formed between the inner surface of the mold c and the surface of the core ball d using the molten resin as a cover material from f to the gate g.
The molten resin is injected into the inside of the cavity, and when the molten resin flows around the support pin e, the support pin e is withdrawn from the cavity h.
By filling the inside of the core ball d with the molten resin, a cover layer is formed on the entire surface of the core ball d to obtain a golf ball in which the core ball d is covered with a cover.

In this case, as shown in FIG. 5, the golf ball i taken out from the mold c after the cover is molded is
In addition to having the ring-shaped resin j cured in the runner f and the gate g of the mold c, burrs k are generated in the PL surface portions of both the mold halves a and b. Therefore, in FIG.
As shown in (A), after the cover is molded, the ring-shaped resin j is cut off from the golf ball i by cutting the ring-shaped resin j at the gate portion g ′ to remove the traces of the cut gate portion g ′ and the burr k. As shown in FIG. 6B, a finishing process is performed to remove pin burrs m, m generated when the support pin e supporting the core ball d is pulled out.

[0005]

However, in the above golf ball manufacturing method, eccentricity is likely to occur, the structure of the mold is complicated, the adjustment work is complicated, and the finishing process after the cover molding is complicated. In addition, it is difficult to form a thin cover, which easily causes problems in appearance.
There are problems such as.

That is, as shown in FIG. 4B, the mold c is provided with 4 to 12 (8 in the figure) gates g at equal intervals around the cavity h. The molten resin is configured to be injected into the cavities in a well-balanced manner. However, in the case of producing a golf ball, in general, a plurality of cavities h are provided in the mold c, and each cavity h is provided. The runners f for injecting the molten resin are connected by the connection runners n, and the molten resin is injected simultaneously into the respective cavities h through the connection runners n. In this case, it is extremely difficult to inject the molten resin in good balance from all the gates g of each cavity, and there is a difference in resin injection timing and injection pressure between the gates g. Likely to occur. Therefore, as shown in FIG. 6A, the core ball d is likely to be laterally displaced and laterally eccentric. Further, as described above, the core ball d is held at the center position of the cavity h by the support pin e arranged in the mold c along the vertical direction, but the length of the support pin e is delicate. Due to the deviation, a vertical deviation may occur as shown in FIG. 6 (B), and a vertical eccentricity may occur.
As described above, the above conventional method is apt to cause eccentricity.

Here, in the case where the lateral eccentricity occurs, it is possible to deal with the problem by enlarging the diameter of the gate by cutting off the slow (bad) gate in order to balance the gate g. When the gate is cut in one cavity, this may affect the flow of resin to the other cavity, and the gate balance in the other cavity may be deteriorated. In this case, the gate may be removed in the other cavity. In that case, the gate balance of the cavity that was shaved first becomes bad again and it may be necessary to grind the gate again, which makes the work of adjusting the gate balance extremely complicated and further grinds the gate. This may cause a problem that the trace of the gate becomes thick and the appearance of the product deteriorates. When the vertical eccentricity occurs, it can be dealt with by changing the length of the support pin e to change the position for supporting the core ball b. In this case, the mold c is disassembled and assembled. Must be done, and in this case very complicated work is required. As described above, in the above-mentioned conventional method, the structure of the mold is complicated, and the adjusting work thereof is extremely complicated.

Further, as described above, the golf ball after the cover is molded needs the finishing treatment for cutting the gate portion g'of the resin and removing the gate trace and the burr k generated on the PL surface portion. Since the pin burr m is likely to be formed around the support pin e, a process step for the pin burr m is also required and a complicated post-process is required. Further, since the support pin e is pulled out after the resin has come around, pin marks are likely to remain on the cover surface, which is not preferable in appearance. in this way,
In the above-mentioned conventional method, the finishing process after molding the cover is complicated, and a problem in appearance is likely to occur.

Further, since the core ball d is an elastic body, it is easily deformed by the pressure when the resin is injected. Further, if the balance of each gate is lost and the position supporting the core ball is displaced even a little, the phenomenon becomes remarkable. This tendency becomes even more pronounced when a particularly thin cover layer is formed. This is because if the core ball is slightly displaced due to the pressure when the cover material is injected, part of the cover layer solidifies before the core ball returns to the center position (before the cover material fills the cavity). It is due to doing. As described above, it is difficult to form a thin cover by preventing the thickness variation by the above-mentioned conventional method.

The present invention has been made in view of the above circumstances, and provides a method for manufacturing a golf ball which solves the above-mentioned problems (1) to (5) and can efficiently and reliably manufacture a high-quality golf ball without eccentricity. The purpose is to provide.

[0011]

In order to achieve the above object, the present invention is a method for producing a golf ball in which a cover layer is injection-molded on the surface of a core ball to obtain a golf ball in which the core ball is covered with a cover. Then, using a first trapezoid having a hemispherical holding recess matching the diameter of the core ball, holding the core ball in the holding recess of the first trapezoid, a hemispherical cavity A first cover forming die having a cover on the hemispherical portion of the core ball protruding from the trapezoidal mold and the first trapezoidal mold, and an inner surface of the first cover molding die and a hemispherical portion surface of the core ball. The cover material is injected into the cavity formed between the two to form a cover layer on the surface of the hemispherical portion of the core ball, and then a second holding recess having a hemispherical shape matching the diameter of the cover layer is formed. A trapezoid is used, and the cover of the core ball is placed in the holding recess of the second trapezoid. Holding the hemispherical portion to form a layer,
A second cover forming die having a hemispherical cavity is covered on the other hemispherical portion of the core ball protruding from the second trapezoidal mold and combined with the second trapezoidal mold to form the second cover forming die. A cover layer is formed on the surface of the other hemisphere of the core sphere by injecting a cover material into a cavity formed between the inner surface of the core and the surface of the other hemisphere of the core sphere. A method for manufacturing a ball is provided.

In this case, the cover mold used as the first cover mold may be reused as the second cover mold, or the cover mold used as the first cover mold. Can also be used as the second trapezoid.

Further, a pin-shaped gate valve for opening and closing the gate is provided in a gate for injecting and injecting the cover material into a cavity formed between the inner surface of the cover mold and the surface of the core ball. The tip of the gate valve has a shape complementary to the dimple shape, the gate valve closes the gate when the cover material is filled in the cavity, and the tip of the gate valve projects into the cavity from the gate. It is possible to form dimples at the gate position of the cover layer at the tip of the protruding gate valve. Furthermore, a cover layer composed of a plurality of layers may be formed by repeating the work of forming the cover layer by the method of the present invention a plurality of times.

[0014]

As described above, the method of manufacturing a golf ball according to the present invention includes the method of supporting the hemispherical portion of the core ball by the first trapezoid, holding the core ball, and projecting the core from the first trapezoid. One hemisphere part of the sphere is covered with a first cover molding die, a cover layer is injection-molded on the hemisphere part, and then one hemisphere part of the core sphere on which the cover layer is formed is supported by a second trapezoidal mold. And hold the core ball,
The other hemisphere portion of the core ball protruding from the second trapezoid is covered with the second cover forming die, and the cover layer is injection-molded on the other hemisphere portion to form a cover layer on the surface of the core ball. Is formed.

As described above, according to the manufacturing method of the present invention, the hemisphere portion of the core ball is supported by the first or second trapezoidal mold to hold the core ball, and in this state, the first or second platform is held. Since the cover layer is formed on the hemispherical portion protruding from the mold, the core sphere does not deviate from being eccentric.

Here, in the method of the present invention, since the covers are molded for each hemisphere, it is possible to uniformly inject the resin into the entire cavity by injecting the molten resin from the apex (pole) of the hemisphere. Gas can be easily degassed from the split surface (PL surface) between the trapezoidal mold and the cover molding die, so that the resin can be well filled into the cavity even when the injection pressure is low. Burrs do not easily occur, and since support pins are not required, pin burrs do not occur due to support pins. Therefore, the finishing process can be performed very easily, and in some cases, the finishing process can be omitted. Furthermore, as mentioned above,
Since the injection pressure of the molten resin can be set to a low pressure, it is possible to prevent deformation of the core ball at the time of injection, which makes it possible to form an extremely uniform cover layer, and thus to reduce the thickness. Even when a thin cover layer having a thickness of 1.5 mm or less is formed, it is possible to cope with it well.

Further, as described above, since the support pin is not required and the gate for injecting the resin only needs to be provided at one place,
Since the structure of the mold is extremely simple and there is no need to balance the gate, there is no need to adjust the mold. Further, as described above, since there is almost no burr and there is no support pin, no pin mark is left and a golf ball having an excellent appearance can be reliably obtained.

Thus, according to the manufacturing method of the present invention,
A high-quality golf ball without eccentricity can be efficiently and reliably manufactured.

Here, in the case of manufacturing a golf ball by covering a core ball with a cover by the method of the present invention, a cover material is injection-injected into a cavity formed between the inner surface of a cover mold and the surface of the core ball. A gate valve having a pin shape for opening and closing the gate is provided in the gate, and the tip of the gate valve has a shape complementary to the dimple shape, and when the cover material is filled in the cavity, the gate valve is opened. When the gate is closed, the tip of the gate valve may protrude from the gate into the cavity, and the tip of the protruding gate valve may form a dimple at the gate position of the cover layer. This makes it possible to form a more beautiful cover layer without leaving a gate mark on the formed cover layer. Further, the cover layer forming operation by the method of the present invention can be repeated a plurality of times to form a cover layer composed of a plurality of layers.

[0020]

EXAMPLES Hereinafter, the present invention will be described more specifically by showing examples. FIG. 1 shows a method for manufacturing a golf ball according to an embodiment of the present invention. First, as shown in FIG. 1 (A), a first holding recess 1a having a hemispherical shape that is aligned with a core ball d is formed. By inserting the core ball d into the holding recess 1a of the one trapezoid 2a and sucking the core ball d from the suction passage 3a communicating with the holding recess 1a provided in the first trapezoid 2a,
The core ball d is held in a state where the hemispherical portion projects from the first trapezoidal mold 2a.

Then, in this state, a first cover molding having a hemispherical cavity 4a having a diameter larger than that of the core ball d in a hemispherical portion of the core ball d protruding from the first trapezoidal mold 2a. The mold is covered with a mold 5a and combined with the first base mold 2a, and an apex portion of the cavity 4a is formed in a cavity 4a formed between the inner surface of the first cover molding mold 5a and the hemispherical surface of the core ball b. Molten resin is injected and injected as a cover material from the gate 6a communicating with the pole portion) to form the cover layer 8a on one hemispherical portion of the core ball d.

A pin-shaped gate valve 7a is arranged in the gate 6a, and the cavity 4 is formed.
As soon as the resin is completely filled in a, the gate valve 7a closes the gate 6a to stop the injection of the resin. In this case, the tip of the gate valve 7a has a shape complementary to the dimples formed on the surface of the cover layer 8a to be molded, and when the gate 6a is closed, the tip extends from the gate 6a to the cavity 4a.
This gate valve 7a is designed to project inside.
A dimple is formed at the position of the gate 6a of the cover layer 8a by the tip of the.

Then, as shown in FIG. 1B, a hemispherical cover layer 8a molded by the first cover molding die 4a.
The second trapezoidal mold 2b having the corresponding holding recess 1b is fitted with the hemispherical portion of the core ball d on which the cover layer 8a is formed, and the holding provided on the first trapezoidal mold 2b. By sucking the core ball d from the suction passage 3b communicating with the recess 1b, the core ball d is held in a state where the other hemisphere portion where the cover layer 8b is not formed protrudes from the second trapezoidal mold 2b.

In this state, a second hemispherical cavity 4b having a diameter larger than that of the core ball d is formed in the other hemisphere portion of the core ball d protruding from the second trapezoidal mold 2b. The cover molding die 5b is put on and combined with the second base mold 2b, and the cavity 4b is formed in a cavity 4b formed between the inner surface of the second cover molding die 5b and the other hemispherical surface of the core ball b. Gate 6 that communicates with the apex (pole) of
A molten resin is injection-injected from b as a cover material to form a cover layer 8b on the other hemispherical portion of the core ball d. This connects the cover layer 8b and the cover layer 8a,
The core ball d is covered with both cover layers 8a and 8b.

In this case, a gate valve 7b is also provided in the gate 6b provided in the second cover molding die 5b, like the gate 6a of the first cover molding die 5a, and inside the cavity 4b. Is completely filled with resin,
Immediately, the gate valve 7b closes the gate 6b to stop the injection of the resin and forms a dimple at the tip of the gate valve 7b at the position of the gate 6a of the cover layer 8b.

Here, the first and second platform dies 2a, 2
b, the first and second cover molding dies 5a and 5b can be prepared separately, but one cover molding die can be used as the first and second cover molding dies 5a and 5b. That is, the first cover mold 5a used when molding the cover layer 8a by the first injection molding is used again as the second cover molding mold 5b when molding the cover layer 8b by the second injection molding. You can also
Further, the first cover molding die 5a can be used as the second platform die 2b. That is, the first cover molding die 5a used when molding the cover layer 8a by the first injection molding.
Can also be used as the second trapezoidal mold 2b when the cover layer 8b is molded by the second injection molding. In this case, the gate 6a of the first cover molding die 5a is replaced with the second base die 2b.
When used as, it can be used as the suction passage 3b. Further, a hot runner or a cold runner may be used as a runner (not shown) for guiding the molten resin to the gates 6a and 6b. When the cord runner is used, the gates 6a and 6b are not of the valve gate type.

A large number of dimples are usually formed on the cover layers 8a and 8b. As shown in FIG. 2, when the dimples 9 are present on the PL surface portion, a broken line 10 is shown in FIG. As shown in (4), the PL surface is unevenly formed along the edge of the dimple 9 ((A)).
), It may be formed in a sawtooth shape (Fig. (B)) or an uneven shape (Fig. (C)) while avoiding the dimples 9.
Among (C), the method shown in (A) is most preferable. Further, the connecting portions of the cover layers 8a and 8b may be meshed with each other in an uneven shape in order to make the connection between the cover layers 8a and 8b good, as shown by a broken line 11 in FIG. In this case, irregularities complementary to these irregularities 11 may be formed on the cover molding surface portion 11a of the first trapezoidal mold 2a (see FIG. 1A).

As described above, in the golf ball manufacturing method of this embodiment, the first trapezoid 2a supports the hemispherical portion of the core sphere d to hold the core sphere d. The first cover molding die 5a is placed on one of the hemispheres of the core ball d protruding from 2a to form a cover layer 8a on the hemisphere, and then one of the core balls d on which the cover layer 8a is formed. The hemisphere part is supported by the second trapezoidal mold 2b to hold the core ball d, and the other hemisphere part of the core ball d protruding from the second trapezoidal mold 2b is covered with the second cover forming mold 5b. The cover layer 8 is formed on the other hemisphere.
The cover layers 8a and 8b are formed on the surface of the core sphere b by hemispheres by injection-molding b.

As described above, in the golf ball manufacturing method of this embodiment, the hemisphere portion of the core ball d is supported by the first trapezoidal mold 2a and the second trapezoidal mold 2b to hold the core ball b, In this state, since the cover layers 8a, 8b are injection-molded on the hemispherical portions protruding from the first or second trapezoidal molds 2a, 2b, the core balls b are displaced and eccentric. There is no end.

Further, the cover layers 8a and 8 are provided on the core sphere b and the hemispheres on the core sphere b.
Since b is molded, the first and second cover molding dies 5a, 5
By injecting the molten resin from the apexes (pole points) of the respective hemispherical cavities 4a and 4b in FIG.
Since it is possible to uniformly inject the resin into the entire a, 4b, in this case, it is possible to easily degas from the split surface (PL surface) between the trapezoidal molds 2a, 2b and the cover molding dies 5a, 5b. Resin with good low injection pressure cavity 4
Since it can be filled in a and 4b, burrs are unlikely to occur on the PL surface, and no pin burrs are generated by the support pins because no support pin is required. Further, the gates 6a and 6b are provided with gate valves 7a and 7b, and the gate valves 7a and 7b are adapted to close the gates 6a and 6b immediately after the resin is filled.
The cover layers 8a, 8b after molding are completely cut off from the resin in the gates 6a, 6b and runners (not shown), and the gates 6a, 6b and runners (not shown) as in the conventional method are removed. There is no need to cut it off. Therefore, the finishing process after the cover molding can be performed very easily, and the finishing process can be omitted in some cases.

Further, as described above, since the injection pressure of the molten resin can be set to a low pressure, it is possible to favorably prevent the core ball from being deformed by the injection pressure at the time of injection, which makes it extremely uniform. The cover layer can be molded. Therefore, it is possible to satisfactorily deal with the case where a thin cover layer having a thickness of 1.5 mm or less is formed.

Further, as described above, since the support pin is not required and the gate for injecting the resin only needs to be provided at one place,
Since the structure of the mold is extremely simple and there is no need to balance the gate, there is no need to adjust the mold. Further, as described above, almost no burr is generated, and since there is no support pin, no pin mark is left and the gate 6
Since dimples are formed in the portions a and 6b by the tip portions of the gate valves 7a and 7b, the gates 6a and 6b are formed.
It is possible to surely obtain a golf ball having an excellent appearance without leaving a gate mark on the part.

The method of manufacturing the golf ball of the present invention is not limited to the above embodiment, and for example, the gate valves 7a and 7b provided on the gates 6a and 6b and the trapezoidal mold 2 are provided.
The suction passages 3a and 3b provided in a and 2b are not necessarily indispensable components, and a normal gate or trapezoid without them may be used. It is also possible to form a cover layer composed of a plurality of layers by repeating the work of forming the cover layer by the method of the above-described embodiment a plurality of times using a plurality of cover molding dies of which the inner diameters are successively increased. Further, other configurations may be variously modified without departing from the gist of the present invention.

[0034]

As described above, according to the method of manufacturing a golf ball of the present invention, the cover is injection-molded on the surface of each core ball, so that a high-quality golf ball without eccentricity can be efficiently and reliably secured. It can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a golf ball manufacturing method of the present invention, in which (A) shows the first injection molding and (B) shows the second injection molding.

FIG. 2 is an explanatory view illustrating a split surface (PL surface) of a mold when a golf ball is manufactured by the manufacturing method.

FIG. 3 is a partially enlarged schematic cross-sectional view showing an example of a connecting portion of a cover layer when a golf ball is manufactured by the manufacturing method.

FIG. 4 shows a conventional golf ball manufacturing method,
(A) is a schematic sectional view, (B) is a sectional view taken along the line BB of (A).

FIG. 5 is a schematic perspective view showing a state of a golf ball having a cover molded by the manufacturing method before finishing treatment.

FIG. 6 is a schematic partially enlarged view illustrating a finishing process of a golf ball having a cover molded by the manufacturing method.

FIG. 7 is an explanatory diagram showing a mode of eccentricity that occurs when a golf ball is manufactured by the manufacturing method.

[Explanation of symbols]

 1a, 1b Holding recess 2a First trapezoid 2b Second trapezoid 3a, 3b Suction path 4a, 4b Cavity 5a First cover mold 5b Second cover mold 6a, 6b Gate 7a, 7b Gate valve 8a, 8b Cover Layer 9 Dimple d Core ball

Claims (5)

[Claims] 1. A cover layer is injection-molded on the surface of a core ball,
A method for producing a golf ball, in which a core ball is covered with a cover, wherein a first trapezoid having a hemispherical holding concave portion matching the diameter of the core ball is used, Holding the core ball in the holding recess, the first cover forming mold having a hemispherical cavity is covered with the hemispherical portion of the core ball protruding from the trapezoidal mold and the first trapezoidal mold, A cover material is injected into a cavity formed between the inner surface of the first cover mold and the surface of the hemisphere portion of the core ball to form a cover layer on the surface of the hemisphere portion of the core ball, and then the above. Using a second trapezoid having a hemispherical holding recess matched to the diameter of the cover layer, holding the hemispherical portion forming the cover layer of the core ball in the holding recess of the second trapezoid,
A second cover forming die having a hemispherical cavity is covered on the other hemispherical portion of the core ball protruding from the second trapezoidal mold and combined with the second trapezoidal mold to form the second cover forming die. A cover layer is formed on the surface of the other hemisphere of the core sphere by injecting a cover material into a cavity formed between the inner surface of the core and the surface of the other hemisphere of the core sphere. Ball manufacturing method. 2. The cover mold used as the first cover mold is also used as the second cover mold.
A method for manufacturing the golf ball described above. 3. The method of manufacturing a golf ball according to claim 1, wherein the cover mold used as the first cover mold is used as the second trapezoid. 4. A pin-shaped gate valve for opening and closing the gate is provided in a gate for injecting and injecting the cover material into a cavity formed between the inner surface of the cover mold and the surface of the core ball. The tip of the gate valve has a shape complementary to the dimple shape, the gate valve closes the gate when the cover material is filled in the cavity, and the tip of the gate valve projects into the cavity from the gate. 4. The method of manufacturing a golf ball according to claim 1, wherein dimples are formed at the gate position of the cover layer at the tip of the protruding gate valve. 5. A method of manufacturing a golf ball, comprising forming a cover layer composed of a plurality of layers by repeating the work of forming the cover layer by the method according to any one of claims 1 to 4 a plurality of times.