JP2006212910A - Golf ball mold and golf ball manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball mold constituted so as to reduce the appearance defectiveness of a golf ball to the utmost by almost eliminating the occurrence of welding and reducing the formation of the burr caused by an intermediate vent pin to manufacture the golf ball of excellent quality, and a golf ball manufacturing method. <P>SOLUTION: In the golf ball mold comprising a split mold composed of upper and lower molds, having a spherical cavity, which has a core and a spherical body comprising a plurality of layers arranged therein, and equipped with a plurality of support pins capable of advancing and retreating with respect to the cavity and a plurality of resin injection gates arranged along the joining surface of the split mold so as to leave a predetermined interval, the intermediate vent pins, which allow the air or gas in the cavity to escape to the outside, are arranged to the outer wall surface of the cavity positioned at a place, where molten resins are converged mutually, or in the vicinity thereof and the arranging number of them is one or two per each split mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a two-piece solid golf ball having a core covered with a single cover layer, a three-piece or more multi-layer solid golf ball molding die having a core covered with a plurality of cover layers, and a method for manufacturing the golf ball.

  Golf balls manufactured by an injection molding method often have product defects due to air remaining in the mold during molding, air taken into the resin, or gas generated from the resin. Therefore, various ideas for degassing have been made.

  For example, as a method for producing a two-piece golf ball by an injection molding method, as shown in FIG. 5, a core 5 is placed in a spherical cavity 4 in a mold or a mold for forming a cover layer comprising an upper mold 2 and a lower mold 3. A plurality of (four in this example) supports that are inserted as cores and further disposed so that the core 5 can be advanced and retracted in the pin receiving holes 6 formed in the upper mold 2 and the lower mold 3, respectively. A plurality of (six in this example) gates 10 provided with pins 7 and then provided with a cover layer material resin 8 in the cavity 4 on the mold fitting surface 9 (near the fitting surface in the case of a tunnel gate). (In this example, the mold fitting surface 9 is at the equatorial plane position of the cavity), and the tip of the support pin 7 is inserted into the cavity 4 immediately before or after the cover layer resin 8 is injected. On the inside In general, a method of covering the core 5 with a cover layer having a large number of dimples by pulling it out so as to fit is adopted, and the support pins 7 of the core have been provided at arbitrary positions and numbers so as to match the dimple shape so far. It was.

  In this case, the injected cover layer material resin 8 flows into the gap 11 between the core 5 and the peripheral wall of the cavity 4, and the flow of this resin usually converges at the deepest location of the cavity 4, thereby the surface of the core 5. The cover layer material resin 8 is coated on the entire surface. For this reason, in the conventional injection molding apparatus, a gas vent hole 12 and a cylindrical fixing pin 13 as described in JP-A-7-80848 are provided at the deepest portion (pole) of the cavity 4, or As described in Japanese Patent Laid-Open No. 63-45040, a degassing movable lead pin has been provided.

  When the golf ball cover layer is formed by the above-described method, so-called weld is generated if gas escape is not good. In other words, the resin injected from each gate should merge with each other to converge and merge at the deepest part (pole) of the cavity. If the gas escape is insufficient, the weld line (boundary) of the individually injected resin Appears on the ball surface.

  Therefore, in order to smoothly and reliably escape the gas during molding to the outside, Japanese Patent Application Laid-Open No. 10-156891 discloses that the injected molten resin converges at the position of the tip of the support pin that supports the core. A molding method and molding in which a support pin is disposed so as to be positioned on the weld line, and gas and air pushed in the direction of the deepest part (pole) of the cavity are effectively released at the position of the support pin. Molds have been proposed.

  However, the role of the support pin is to stably hold the core in the cavity. However, in the above proposed molding method (molding die), the support pin that is restricted in the arrangement on the weld line is the core. The role of stably supporting this may be impaired. That is, the position of the weld line fluctuates depending on the flow rate and injection amount of the molten resin, the arrangement and number of injection gates, and if a weld line is generated near the pole of the cavity, the arrangement position of the support pin is also the cavity. There is an inconvenience that the core support becomes unstable due to concentration in the vicinity of the poles.

  In addition, the support pin must be configured to be located on the weld line, which restricts the arrangement of dimples on the ball surface. In recent golf balls, many dimples are arranged on the ball surface with high density and uniformity, and the arrangement of one support pin has a great influence on the dimple arrangement.

Japanese Patent Laid-Open No. 7-80848 Japanese Patent Laid-Open No. 63-45040 Japanese Patent Laid-Open No. 10-155891

  The present invention has been made in view of the above circumstances, and can sufficiently and reliably escape the gas and air generated in the cavity, eliminate the generation of weld lines, and minimize the formation of burrs. It is an object of the present invention to provide a golf ball manufacturing method and a golf ball molding die capable of obtaining a golf ball having almost no poor appearance on the ball surface.

In order to achieve the above object, the present inventor provides the following golf ball manufacturing method and golf ball molding die.
[1] A split mold of upper and lower molds, having a spherical cavity in which a spherical body composed of a core or a plurality of layers is disposed, and a plurality of support pins each capable of moving back and forth in the cavity; In a golf ball molding die provided with a plurality of resin injection gates spaced apart by a predetermined distance along the joining surface, an intermediate vent pin for escaping air or gas in the cavity to the outside is provided with molten resin. A golf ball molding die, which is disposed on a cavity outer wall surface located at or near a converging portion, and the number of arrangement is one or two for each split mold.
[2] The golf ball molding die according to [1], wherein the hole diameter of the intermediate vent pin is 0.8 to 6.0 mm.
[3] The golf ball molding die according to [1] or [2], wherein an injection amount of the molten resin injected into the cavity is 5 to 15 cc.
[4] The golf ball according to any one of [1] to [3], wherein the intermediate vent pin is disposed at a latitude of 60 to 85 ° when the spherical cavity joint surface of each split mold is regarded as the equator. Mold.
[5] The golf ball molding die according to any one of [1] to [4], wherein the number of the support pins is 3 to 6 for each split mold.
[6] At the center of the spherical cavity of the upper and lower mold dies, a spherical body consisting of a core or a plurality of layers is supported by a plurality of support pins capable of moving back and forth toward the cavity, and the joint surface of the upper and lower mold split molds A golf club in which a molten resin is injected into the cavity from a plurality of resin injection gates arranged at predetermined intervals along the core, and the molten resin is injection molded around the core or the spherical body to form a cover layer In the ball manufacturing method, the gas in the cavity is allowed to escape to the outside from one or two intermediate vent pins for each split mold disposed on the outer wall surface of the cavity located at or near the location where the molten resin converges. A method for producing a golf ball, comprising injection molding a molten resin.
[7] When manufacturing a three-piece solid golf ball comprising a core, a cover layer, and an intermediate layer interposed therebetween, a cover having a thickness of 0.5 to 2.0 mm around a spherical body comprising the core and the intermediate layer The method for producing a golf ball according to [6], wherein the layer is covered to form a three-piece solid golf ball.

  According to the present invention, when the molten resin is injected into the mold cavity from a plurality of resin injection gates arranged at predetermined intervals along the joining surface of the upper and lower mold split molds, the molten resins converge on each other. On the outer wall surface of the cavity located at or near the location (that is, near both poles of the spherical cavity), there are limited to one or two intermediate vent pins each having a predetermined diameter that serves as a vent pin. Because it communicates with the cavity, the gas or air in the cavity can be sufficiently escaped from the intermediate vent pin, the occurrence of weld lines can be prevented, and the number of intermediate vent pins can be reduced as much as possible. The burr formed on the trace can be reduced as much as possible, and the appearance defect on the ball surface can be almost eliminated.

  Further, according to the present invention, it is possible to escape the gas or air in the cavity to the outside through the gap between the support pin and the pin hole arranged so as to be able to advance and retract toward the cavity. Therefore, it is not necessary to arrange the support pin on the weld line so that the gas can be sufficiently vented, and the support pin can be freely used so that it can fully fulfill the original role of supporting the core. Can be arranged.

  According to the golf ball molding die and the manufacturing method of the present invention, it is possible to eliminate the occurrence of welds, reduce the formation of burrs caused by the intermediate vent pins, and reduce the appearance defects of the ball as much as possible. A golf ball excellent in quality can be manufactured.

The golf ball molding die and manufacturing method of the present invention will be described below with reference to the drawings.
FIG. 1 shows an arrangement example of runners, gates, support pins, pole vent pins, and intermediate vent pins in a golf ball molding die according to a first embodiment (embodiment 1) of the present invention. Reference numeral 40 is a runner, 33 is an injection gate, 32 is a support pin, and 35 is an intermediate vent pin. In this embodiment, as shown in FIG. 1, an intermediate vent pin 35 for escaping the gas in the cavity to the outside is disposed on the outer wall surface 31 of the cavity 36 located at or near the location where the molten resins converge with each other. The number of arrangement is one for each split mold 30a, 30b. Other than that, it is the same component as the conventional molding die shown in FIG. In addition, the vent hole of the code | symbol 38 in FIG. 1 is a pole vent pin located in the both poles of a cavity, respectively, The pin hole diameter is 0.8-6.0 mm, and is arrange | positioned with the intermediate vent pin 35 said by this invention The position is different.

FIGS. 2-4 show the arrangement | positioning aspect of the runner in the shaping | molding die of the golf ball which concerns on Example 1- Example 12 including the said Example, a gate, a support pin, a pole vent pin, and an intermediate | middle vent pin. In the drawings in each embodiment, the arrangement of the runner, the gate, the support pin, and the intermediate vent pin can be grasped with reference to FIG. In the figure, the arrow indicates the inflow direction of the resin, and in a light-colored spherical surface representing the ball surface, black circles and white circles are marks of intermediate vent pins and support pins on the ball surface, respectively. In addition, in the center position of the drawings of each embodiment, there is also a case where a small circle (white) is drawn, which indicates a pole vent pin. In the present invention, it is shown in each embodiment of FIGS. As described above, the intermediate vent pin is limited to one or two for each of the upper mold and the lower mold. If the number of intermediate vent pins arranged in each split mold is three or more, the air or gas in the cavity can be effectively scattered to the outside by an increase in the number. On the other hand, a relatively large burr is formed on the cavity wall surface where the intermediate vent pin communicates due to the arrangement of the intermediate vent pin. As a result of polishing a part of the ball surface in order to remove the burr, the ball performance There is an inconvenience that greatly affects. Therefore, from the viewpoint of reducing the number of intermediate vent pins as much as possible, in the present invention, the number of intermediate vent pins is limited to one or two for each split mold.

  About the position of said intermediate | middle vent pin, when considering the spherical cavity joint surface of each split type | mold as an equator, it is desirable that an intermediate | middle vent pin is arrange | positioned in the position of latitude 45-85 degrees, especially 60-85 degrees. Here, the latitude is an intersection angle α between an equator plane (PL plane) passing through the center of the cavity and a perpendicular line toward the center of the cavity in the intermediate vent pin, as shown by a dotted line portion in FIG. Specifically, the location where the resin converges depends on the flow rate of the molten resin, the number of injection gates, the location of the injection, the thickness of the cover (space volume of the cavity), etc. Is shifted from both poles of the cavity to the side where the final runner is located, and the molten resin material having low fluidity is shifted from both poles of the cavity in the opposite direction where the final runner is located. Therefore, in consideration of the melt flow rate (MFR) of the resin material used, the position where the molten resin converges is grasped by a preliminary experiment or the like, and an intermediate vent pin is predicted at one or two of the converged positions. Can be arranged.

  As described above, vent pins (reference numeral 38 in FIG. 1) can be arranged on both poles of the cavity.

The hole diameter of the intermediate vent pin is preferably 2 to 6 mm, particularly preferably 2 to 3 mm. Although it depends on the size of the hole diameter of the intermediate vent pin, the clearance between the pin and the hole diameter is preferably in the range of 5 to 40 μm. If the hole diameter or clearance of the intermediate vent pin is too larger than a predetermined value, a molding defect does not occur due to the degassing effect, but a burr becomes large and an appearance defect is caused.

  The injection amount of the molten resin injected into the cavity, that is, the space volume of the cavity for forming the cover, is 5 to 15 cc, particularly 8 to 12 cc, in order to sufficiently function as a cover. Is preferred.

  In the present invention, the number of support pins (reference numeral 32 in FIG. 1) is not particularly limited, but when the molten resin flowing in the cavity contacts the outer peripheral surface of the support pins, the surface temperature of the support pins is melted. Since it is lower than the resin, the portion where the support pin is disposed becomes brittle and tends to be easily broken by repeated hitting of the ball. For this reason, it is preferable to set the number of support pins to 3 to 6, particularly 3 to 4, with as few as possible.

In the present invention, as shown in FIG. 1A, the mold 30 is provided with a plurality of (six locations in FIG. 1) gates 33 around the cavity 36 at equal intervals, Is injected into the cavity in a well-balanced manner. When a golf ball is manufactured, a plurality of cavities 36 are provided in a mold, and the runners 40 for injecting molten resin into the cavities 36 are connected by connecting runners 41. By injecting molten resin into each cavity simultaneously through 41, it is preferable to manufacture a plurality of golf balls simultaneously with a set of molds 30.

  There are no particular restrictions on the number of injection gates used in the present invention, the arrangement position, etc., but six or eight injection gates are allowed to flow in the molten resin uniformly and in a balanced manner from the viewpoint of restrictions on dimple arrangement. It is desirable to arrange the injection gates so as to face each other evenly. Further, the shape of the final runner used in the present invention is not particularly limited, such as a ring shape or a horseshoe shape.

  In the present invention, the core constituting the golf ball is not particularly limited. For example, a solid core for two-piece balls, a solid core having a plurality of vulcanized rubber layers, a solid core having a plurality of resin layers, and a thread wound core having a thread rubber layer Various cores can be used. In the present invention, a three-piece solid golf ball including a core, a cover layer, and an intermediate layer interposed therebetween is manufactured, and a spherical body formed by covering the core with the intermediate layer is disposed in the cavity. You can also As the material for the intermediate layer, a known thermoplastic resin or thermoplastic elastomer can be suitably used.

As the material of the cover layer, a known thermoplastic resin or thermoplastic elastomer mainly composed of ionomer resin or urethane resin can be suitably used. As described above, the fluidity (MFR) of the resin material can be used. It is preferable to select the material in consideration of the above.
The thickness of the cover layer is particularly preferably 0.5 to 2.0 mm. The cover layer is not limited to a single layer and can be formed in a multilayer structure.

  The golf ball manufactured by the molding die and the manufacturing method of the present invention is preferably formed to have a diameter and a mass in accordance with the golf regulations, and usually has a diameter of 42.67 mm or more and a mass of 45.93 g or less.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Examples 1-4, Comparative Examples 1-4]
A core material having the following composition was kneaded.
Core composition Polybutadiene rubber (trade name: BR730) 50 parts by mass polybutadiene rubber (trade name: BR01) manufactured by JSR 50 parts by mass zinc acrylate 23.2 parts by mass Dicumyl peroxide (trade name: Park Mill D) manufactured by NOF Corporation 0.6 parts by mass 1,1 bis (t-butylperoxy) 3,3,5-trimethylcyclohexane (trade name: Perhexa 3M-40) manufactured by NOF Corporation 0.6 parts by mass Inhibitor (trade name: NOCRACK NS-6) 0.1 parts by mass of zinc oxide 28.6 parts by mass, manufactured by Ouchi Shinsei Chemical Co., Ltd.

The above core material was vulcanized at 155 ° C. for 15 minutes to obtain a solid core having a diameter of 37.6 mm. When the solid core was loaded with an initial load of 10 kgf to a final load of 130 kgf, the amount of deformation was 3.7 mm.

Next, an intermediate layer material having the following composition was prepared.
Intermediate layer material Ionomer resin (trade name: Surlyn 8120) 75 parts by mass block copolymer polybutadiene hydrogenated product (trade name: Dynalon E6100P) manufactured by DuPont
25 parts by mass behenic acid (trade name: NAA222-S beads designated) 20 parts by mass calcium hydroxide (trade name: CLS-B designated) 2.3 parts by mass manufactured by Shiroishi Kogyo Co., Ltd.

When the melt flow rate (MFR) of the intermediate layer material having the above composition was measured according to JIS-K6760 [test temperature 190 ° C., test load 21 N (21.6 kgf)], the MFR value was 2.1 g / 10 min. It was. Further, when the intermediate layer material was formed into a sheet and measured based on ASTM-D2240, the Shore D hardness was 51. The specific gravity of the intermediate layer material was 0.94. This material was coated on the solid core to form an intermediate layer. The thickness of the intermediate layer was 1.28 mm, the outer diameter of the sphere in which the intermediate layer was coated on the solid core was 40.15 mm, and the weight was 39.0 g.

  Next, by using the injection molds of Examples 1 to 4 and Comparative Examples 1 to 4 having the arrangement of the ring-shaped runner, injection gate, support pin and intermediate vent pin shown in FIG. Cover layer materials A and D were injection molded to produce a three-piece solid golf ball. The cover layer materials A and D are as follows.

＊上記の商品名「ハイミラン」シリーズは、三井・デュポンポリケミカル社製の製品
＊上記の商品名「ハイミランＡＤ８５２６」は、三井・デュポンポリケミカル社製の製品

* The above-mentioned product name "Hi-Milan" series is a product made by Mitsui DuPont Polychemical Co., Ltd. * The above-mentioned product name "Hi-Milan AD8526" is a product made by Mitsui DuPont Polychemical Co., Ltd.

Further, the Shore D hardness of the cover layer material A was 61, the Shore D hardness of the cover layer material D was 66, and the thickness of the cover layer was 1.275 mm.

About 500 of the obtained golf balls were manufactured, and the weld generation rate and appearance defect rate were examined according to the following criteria. The results are shown in Table 2 below.
The weld occurrence rate is a value obtained by averaging the defective rate obtained by visually inspecting the golf ball after the cover was injection molded by five inspectors.
Appearance defect rate This is a value obtained by averaging the defect rates obtained by visually inspecting the bent pin marks after the golf balls after the cover injection molding were subjected to spherical polishing according to a conventional method.
Observe by

[Examples 5-8, Comparative Examples 5-8]
The composition of the solid core and the composition of the intermediate layer material are all the same as in the above example. Using the injection molds of Examples 5 to 8 and Comparative Examples 5 to 8 having the arrangement of the horseshoe-shaped runner, injection gate, support pin and intermediate vent pin shown in FIG. A three-piece solid golf ball was prepared by injection molding the cover layer material B into a predetermined sphere. This cover layer material B is as follows.

＊上記の商品名「サーリン９９４５」は、デュポン社製の製品

* The product name "Surlin 9945" is a product made by DuPont.

The cover layer material B had a Shore D hardness of 63 and a cover layer thickness of 1.275 mm.

※ウエルド発生率と外観不良率の評価基準は表２と同じである。

* The evaluation criteria for weld incidence and appearance defect rate are the same as in Table 2.

[Examples 9-12, Comparative Examples 9-12]
The composition of the solid core and the composition of the intermediate layer material are all the same as in the above example. Using the injection molds of Examples 9-12 and Comparative Examples 9-12 having the arrangement of the horseshoe-shaped runner, injection gate, support pin, and intermediate vent pin shown in FIG. A three-piece solid golf ball was produced by injection molding the cover layer material C into a predetermined sphere. This cover layer material C is as follows.

  Further, the Shore D hardness of the cover layer material C was 63, and the thickness of the cover layer was 1.275 mm.

※ウエルド発生率と外観不良率の評価基準は表２と同じである。

* The evaluation criteria for weld incidence and appearance defect rate are the same as in Table 2.

FIG. 1 (A) is a plan view showing a golf ball molding die according to one embodiment of the present invention, and FIG. 1 (B) is an AA cross-sectional view thereof. It is the schematic diagram which showed arrangement | positioning positions, such as an intermediate | middle vent pin, in the surface of the golf ball immediately after the injection molding by each Example (Examples 1-4, Comparative Examples 1-4). It is the schematic diagram which showed arrangement | positioning positions, such as an intermediate | middle vent pin, in the surface of the golf ball immediately after the injection molding by each Example (Examples 5-8, Comparative Examples 5-8). It is the schematic diagram which showed arrangement | positioning positions, such as an intermediate | middle vent pin, in the surface of the golf ball immediately after the injection molding by each Example (Examples 9-12, Comparative Examples 9-12). It is sectional drawing which showed the conventional metal mold | die for golf ball shaping | molding.

Explanation of symbols

30 Golf Ball Mold 30a Upper Mold 30b Lower Mold 32 Support Pin 35 Intermediate Vent Pin 5a Core 5 Spherical Body

Claims (7)

  The upper and lower molds have a spherical cavity in which a core or a multi-layered spherical body is disposed, and a plurality of support pins that can be advanced and retracted into the cavity, respectively, and a joint surface of the split mold In a golf ball molding die provided with a plurality of resin injection gates arranged at a predetermined interval along the middle, the molten resin converges on the intermediate vent pin for escaping air or gas in the cavity to the outside. Alternatively, a golf ball molding die, which is disposed on an outer wall surface of a cavity located in the vicinity thereof, and the number thereof is one or two for each split mold.   2. The golf ball molding die according to claim 1, wherein the hole diameter of the intermediate vent pin is 0.8 to 6.0 mm.   The golf ball molding die according to claim 1 or 2, wherein an injection amount of the molten resin injected into the cavity is 5 to 15 cc.   The golf ball molding die according to any one of claims 1 to 3, wherein the intermediate vent pin is disposed at a latitude of 60 to 85 ° when the spherical cavity joint surface of each split mold is regarded as the equator.   The golf ball molding die according to any one of claims 1 to 4, wherein the number of the support pins is 3 to 6 for each split mold.   At the center position of the spherical cavity of the upper and lower molds, a spherical body consisting of a core or a plurality of layers is supported by a plurality of support pins that can advance and retreat toward the cavity, and along the joint surface of the upper and lower mold split molds. Manufacturing of a golf ball in which a molten resin is injected into the cavity from a plurality of resin injection gates arranged at predetermined intervals, and the molten resin is injection molded around the core or the spherical body to form a cover layer In the method, the molten resin is discharged by letting the gas in the cavity escape to the outside from one or two intermediate vent pins for each split mold disposed on the cavity outer wall located at or near the location where the molten resins converge with each other. A golf ball manufacturing method, characterized by injection molding. When manufacturing a three-piece solid golf ball comprising a core, a cover layer, and an intermediate layer interposed therebetween, a cover layer having a thickness of 0.5 to 2.0 mm is coated around a spherical body made of the core and the intermediate layer. The method of manufacturing a golf ball according to claim 6, wherein a three-piece solid golf ball is formed.

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