JP2004322347A - Mold for molding golf ball and golf ball manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold 1 for molding a golf ball, constituted so as to easily discharge air. <P>SOLUTION: The lower mold L of the mold 1 is equipped with six gates G, one pole vent pin P, three support pins S, three first fixed pins F and three second fixed pins (f). All of the support pins S, the first fixed pins F and the second fixed pins (f) are intermediate vent pins. The latitude θ of the center of the intermediate vent pins is 45-85°. The support pins S can advance and retreat with respect to a cavity and the pole pin P, the first fixed pins F and the second fixed pins (f) are immovable. Longitude lines having the center values with the longitude ϕ of one gate and the longitudes ϕ of the other gates adjacent to one gate are center longitude lines M and the respective center longitude lines M cross at least one of the intermediate vent pins S, F and (f). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４２】
［実施例１］
図２に示された成形型に、直径が４１．１ｍｍのソリッドコアを投入し、このコアの周りにタイプＡのカバー材料を射出して、ゴルフボールを得た。このゴルフボールのカバー厚みは、０．８ｍｍであった。
【００４３】
［実施例２及び８］
コアの直径を異ならせた他は実施例１と同様にして、ゴルフボールを得た。カバーの厚みが、下記の表２及び３に示されている。
【００４４】
［実施例３から７及び比較例１］
下記の表２及び３に示される成形型を用いた他は実施例１と同様にして、ゴルフボールを得た。比較例１で用いた金型では、図９に示されるように、中心経線Ｍの上に中間ベントピンが存在していない。
【００４５】
［実施例９］
タイプＢのカバー材料を用いた他は実施例１と同様にして、ゴルフボールを得た。
【００４６】
［不良発生数のカウント］
下記表２及び３に示される数ゴルフボールを作成し、ベアー、エアー咬み込み及びウエルドマークの発生数を目視でカウントした。この結果が、下記の表２及び３に示されている。
【００４７】
［偏肉度の測定］
ゴルフボールをＸ線で検査し、カバー厚みの最大箇所と最小箇所とを特定した。最大箇所の厚みから最小箇所の厚みを減じた値を、偏肉度とした。１００個のゴルフボールについて得られた偏肉度の平均値が、下記の表２及び３に示されている。
【００４８】
【表２】

【００４９】
【表３】

【００５０】
表２及び３において、中心経線の上に中間ベントピンが存在しない比較例１の成形型では、不良率が高い。中心経線の上に５本のサポートピンが存在する実施例７の成形型では、ベアーが発生しやすく、偏肉も生じやすい。これは、サポートピンが溶融樹脂組成物の流動を阻害しているためと推測される。さらに、第一固定ピンの緯度が大きな実施例４の成形型では、エアーの咬み込み及びウエルドマークが若干発生している。これは、極ベントピンのクリアランスがふさがった段階で残留しているエアーが排出されにくいためと推測される。
【００５１】
【発明の効果】
以上説明されたように、本発明の成形型ではエアーが排出されやすい。この成形型により、高品質なゴルフボールが得られる。この成形型が用いられた製造方法では、歩留まりが高い。
【図面の簡単な説明】
【図１】図１は、本発明の一実施形態に係るゴルフボール用成形型が示された断面図である。
【図２】図２は、図１の成形型の下型が示された平面図である。
【図３】図３は、図２の下型の一部が示された拡大図である。
【図４】図４は、本発明の他の実施形態に係る成形型の下型が示された平面図である。
【図５】図５は、本発明のさらに他の実施形態に係る成形型の下型が示された平面図である。
【図６】図６は、本発明のさらに他の実施形態に係る成形型の下型が示された平面図である。
【図７】図７は、本発明のさらに他の実施形態に係る成形型の下型が示された平面図である。
【図８】図８は、本発明のさらに他の実施形態に係る成形型の下型が示された平面図である。
【図９】図９は、本発明の比較例１に係る成形型の下型が示された平面図である。
【符号の説明】
１・・・ゴルフボール用成形型
３・・・キャビティ面
５・・・ピンプル
７・・・パーティングライン
９、１１、１３・・・ピン孔
ｆ・・・第二固定ピン
Ｆ・・・第一固定ピン
Ｇ・・・ゲート
Ｌ・・・下型
Ｍ・・・中心経線
Ｐ・・・極ベントピン
Ｓ・・・サポートピン
Ｕ・・・上型[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a golf ball mold and a golf ball manufacturing method. More specifically, the present invention relates to an improvement in a mold used for molding a cover of a golf ball.
[0002]
[Prior art]
A two-piece golf ball includes a core and a cover that covers the surface of the core. In the production of a two-piece golf ball, a mold having an upper mold and a lower mold having both hemispherical cavities is used. By combining the upper mold and the lower mold, a spherical cavity is formed. This mold includes a support pin that can move forward and backward with respect to the cavity, and a vent pin for communicating the cavity with outside air. The vent pins are provided at the extreme points of the upper mold and the lower mold. The advanced support pin holds the core in the center of the cavity. Then, the resin composition is put into an injection molding machine, melted, and injected toward a cavity through a plurality of gates. The molten resin composition is filled between the cavity surface and the core. The molten resin composition coats the periphery of the core and then solidifies to form a cover.
[0003]
When the core is held by the support pins, air exists between the cavity surface and the core. As the molten resin composition is injected into the cavity, the air in the cavity is discharged to the outside. The discharge is performed from the clearance between the support pin and the vent pin. A molding die that uses a support pin made of a porous material and discharges air from the support pin has also been proposed (JP-A-2000-37480).
[0004]
[Patent Document 1]
JP 2000-37480 A
[0005]
[Problems to be solved by the invention]
Insufficient air discharge causes defects such as generation of bears, biting of air into the cover, burning of resin, and generation of weld marks. In molding a thin cover, the molten resin composition is unlikely to flow, so that defects are particularly likely to occur.
[0006]
The molten resin composition injected from the first gate merges with the molten resin composition injected from the second gate adjacent thereto. Air tends to remain at the junction. If the molten resin composition blocks the clearance of the extreme vent pin before the filling of the entire cavity with the molten resin composition is completed, there is a high possibility that air remains at the junction.
[0007]
Some golf balls have a cover made of two or more layers. Also in the formation of each layer of the golf ball, air remains a problem.
[0008]
An object of the present invention is to provide a molding die for a golf ball from which air is easily discharged. Another object of the present invention is to provide a method for manufacturing a golf ball that can provide a high-quality golf ball and has a high yield.
[0009]
[Means for Solving the Problems]
The golf ball mold according to the present invention comprises an upper mold and a lower mold. This mold includes a substantially spherical cavity, a plurality of gates through which the polymer composition injected into the cavity passes, and a plurality of intermediate vent pins having a center θ of 45 ° or more and 85 ° or less. Have. In this molding die, when a meridian having a center value between the longitude φ of one gate and the longitude φ of another gate adjacent to this gate is taken as the center meridian, the upper mold and the lower mold each have a cavity surface. Any central meridian present intersects or touches the intermediate vent pin. In this mold, air does not easily remain.
[0010]
Preferably, in each of the upper and lower dies, all of the central meridians intersect the intermediate vent pin. The ratio R of the intersection width to the radius of the intermediate vent pin is 50% or more in longitude conversion. In this mold, the residual air at the junction of the polymer composition is suppressed.
[0011]
Preferably, the number of intermediate vent pins intersecting or contacting the central meridian is 6 or more and 18 or less in each of the upper mold and the lower mold. From the viewpoint of smooth flow of the polymer composition, it is preferable that all of the intermediate vent pins intersecting with or in contact with the central meridian are fixed pins.
[0012]
An intermediate vent pin that intersects or touches the central meridian may include a fixed pin and a support pin that is retractable with respect to the cavity. In each of the upper mold and the lower mold, the number of support pins that intersects or contacts the central meridian is 3 or more and 6 or less, and the number of fixed pins that intersects or contacts the central meridian is 3 or more and 10 or less. It is. Preferably, the number of support pins intersecting or contacting the central meridian is three or four.
[0013]
Golf ball manufacturing method according to another invention,
(1) It comprises an upper mold and a lower mold, and has a substantially spherical cavity, a plurality of gates, and a plurality of intermediate vent pins whose central latitude θ is 45 ° or more and 85 ° or less. When the meridian having the center value of the longitude φ of the gate and the longitude φ of another gate adjacent to this gate is taken as the center meridian, in each of the upper mold and the lower mold, all the center meridians existing on the cavity surface are A step in which the core is put into a mold that intersects or contacts the intermediate vent pin, and
(2) A step in which the polymer composition is injected into the cavity through the gate while the air existing in the cavity is exhausted from the clearance of the intermediate vent pin.
including. By this manufacturing method, a high-quality golf ball can be obtained.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.
[0015]
FIG. 1 is a cross-sectional view illustrating a molding die 1 for a golf ball according to an embodiment of the present invention. The molding die 1 includes an upper die U and a lower die L. Each of the upper mold U and the lower mold L has a hemispherical cavity surface 3. In FIG. 1, a spherical cavity is formed by combining the upper mold U and the lower mold L. A large number of pimples 5 are formed on the cavity surface 3. The pimple 5 has a shape in which the shape of the dimple is inverted. In this mold 1, when the deepest part of the cavity surface 3 of the upper mold U is assumed to be the north pole of the globe, and the deepest part of the cavity surface 3 of the lower mold L is assumed to be the south pole of the globe, The parting line 7 between the lower mold L and the lower mold L corresponds to the equator. In this specification, the position on the cavity surface 3 is represented by spherical polar coordinates (θ, φ). θ corresponds to the north latitude or the south latitude of the globe. The range of the latitude θ is from 0 ° to 90 °. φ corresponds to the longitude of the globe. The range of longitude φ is 0 ° to 360 °.
[0016]
FIG. 2 is a plan view showing a lower mold L of the molding die 1 of FIG. The bottom view of the upper mold U has a shape in which FIG. 2 is turned upside down. Each of the upper mold U and the lower mold L has six gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 60 °. What is indicated by a two-dot chain line in FIG. 2 is a central meridian M. The central meridian M is an arc connecting the parting line 7 and the pole. The longitude φ of the central meridian M is the central value of the longitude φ of each of the two gates G adjacent to each other across the central meridian M. For example, the longitude φ of the central meridian M located between the gate G whose longitude φ is 240 ° and the gate G whose longitude φ is 300 ° is 270 °. The length of the central meridian M is 1/4 of the circle. The lower mold L shown in FIG. 2 has six central meridians M. The longitude difference between adjacent center meridians M is 60 °. Although not shown, the upper die U also has six central meridians M similarly.
[0017]
Each of the upper mold U and the lower mold L includes one pole vent pin P, three support pins S, three first fixing pins F, and three second fixing pins f. The support pin S, the first fixing pin F, and the second fixing pin f are all intermediate vent pins. In this specification, the intermediate vent pin means a vent pin whose center (latitude center) has a latitude θ of 45 ° or more and 85 ° or less. As is evident from FIG. 2, on one central meridian M there is at least one intermediate vent pin S, F, f. In other words, all central meridians M intersect or touch the intermediate vent pins S, F, f. The number of support pins S existing on the central meridian M is zero. The number of the fixing pins F and f existing on the central meridian M is six.
[0018]
The tip of the pole vent pin P coincides with the pole of the cavity surface 3. In other words, the latitude θ of the tip of the pole vent pin P is 90 °. The three support pins S are arranged at equal intervals. The longitude difference between adjacent support pins S is 120 °. The latitude of each support pin S is the same as each other. The three first fixing pins F are arranged at equal intervals. The longitude difference between adjacent first fixed pins F is 120 °. The latitude of each first fixing pin F is the same as each other. The three second fixing pins f are arranged at equal intervals. The longitude difference between adjacent second fixed pins f is 120 °. The latitude of each second fixing pin f is the same as each other. The pole vent pin P and the intermediate vent pins S, F, f are made of carbon steel, alloy steel, or the like. The pole vent pin P and the intermediate vent pins S, F, f may be formed from a porous material.
[0019]
As shown in FIG. 1, the pole vent pin P is inserted into the pin hole 9. The clearance between the pole vent pin P and the pin hole 9 communicates the outside of the mold 1 with the spherical cavity. The support pin S is inserted into the pin hole 11. The clearance between the support pin S and the pin hole 11 communicates the outside of the mold 1 with the spherical cavity. The first fixing pin F is inserted into the pin hole 13. The clearance between the first fixing pin F and the pin hole 13 communicates the outside of the mold 1 with the spherical cavity. Although not shown in FIG. 1, the second fixing pin f is also inserted into the pin hole similarly to the first fixing pin F, and its clearance communicates the outside of the mold 1 with the spherical cavity. As shown in FIG. 1, the tip of the pole vent pin P is flat, and the tips of the support pin S and the first fixing pin F are convex. Although not shown in FIG. 1, the tip of the second fixing pin f is also convex. The cross sections of the pole vent pin P, the support pin S, the first fixing pin F, and the second fixing pin f are circular.
[0020]
The support pin S can move forward and backward with respect to the cavity. The support pin S is moved by means (not shown) (for example, a hydraulic cylinder). The pole vent pin P, the first fixing pin F, and the second fixing pin f are immobile.
[0021]
In order to manufacture a golf ball by an injection molding method using the molding die 1, first, a core is put into a cavity of the lower die L. Next, the mold is clamped, and the support pin S moves forward. The support pin S holds the core by advancing. The core is located at the center of the spherical cavity. Air exists between the cavity surface 3 and the core. Next, the molten resin composition passes through the gate G and is injected into the spherical cavity. The molten resin composition flows toward an extreme point. With the flow, air existing between the cavity surface 3 and the core is gradually discharged to the outside. The discharge is performed from the clearance between the pole vent pin P, the support pin S, the first fixing pin F, and the second fixing pin f. Immediately before the injection of the molten resin composition is completed, the support pin S retreats. Although the tip of the support pin S is separated from the core, the core hardly moves because the resin composition exists between the core and the cavity surface 3. After the injection of the molten resin composition is completed and the resin composition solidifies, the mold 1 is opened and the golf ball is taken out. This golf ball has a core and a cover made of a resin composition. On the surface of the cover, dimples having a shape in which the pimples 5 are inverted are formed. Dimples are also formed by the tips of the support pin S, the first fixing pin F, and the second fixing pin f. Burrs are formed on the surface of the golf ball at locations corresponding to the clearance. If the size of the burr is large, the burr is removed by grinding.
[0022]
The molten resin composition is injected almost simultaneously from the six gates G. The molten resin composition flows toward the poles while spreading in the longitude direction. The molten resin composition injected from one gate G and the molten resin composition injected from another gate G adjacent to this gate G merge. The junction moves from the vicinity of the parting line 7 toward the pole. The locus of the junction is called a weld line. The weld line substantially coincides with the central meridian M. In the conventional molding die 1, air tends to remain on the weld line. In the mold 1 shown in FIGS. 1 and 2, since at least one intermediate vent pin S, F, f exists on the central meridian M as described above, the intermediate vent pin S, F, f The residual air is suppressed by the discharge. The molding die 1 provides a high quality golf ball. In the manufacturing method using the molding die 1, the yield is high.
[0023]
Ideally, the respective molten resin compositions injected from the respective gates G flow at substantially the same speed and reach the poles almost simultaneously. During the flow process, the clearances of the intermediate vent pins S, F, and f are closed by the molten resin composition, and thereafter, air is discharged from the clearance of the pole vent pins P. When the gate balance is broken for some reason and the molten resin composition injected from one gate G blocks the clearance of the pole vent pin P before the molten resin composition injected from one gate G reaches the extreme point. However, due to the large number of intermediate vent pins S, F, and f existing on the central meridian M, air residue is suppressed.
[0024]
When the tip of the pole vent pin P corresponds to a dimple, the tip is convex. When the tip of the support pin S, the first fixing pin F, or the second fixing pin f corresponds to a land (an area other than the dimple on the surface of the golf ball), the tip is flat.
[0025]
FIG. 3 is an enlarged view showing a part of the lower mold L of FIG. FIG. 3 shows one intermediate vent pin (for example, a support pin S) and a central meridian M. In FIG. 3, the upper side is the pole side, and the lower side is the parting line 7 side. The central meridian M extends in the vertical direction in FIG. In FIG. 3, what is indicated by a double-headed arrow r is the radius of the support pin S. On the other hand, what is indicated by the double-headed arrow w is the intersection width between the central meridian M and the support pin S. The ratio R of the intersection width w to the radius r of the support pin S is preferably 50% or more, and more preferably 80% or more. The larger the ratio R, the less air remains. The ratio R is ideally 100%. In other words, ideally, the central meridian M passes through the center of the support pin S. The radius r and the intersection width w are calculated by longitude conversion. When the longitude of the portion F1 where the longitude φ is the smallest among the support pins S is φ1, and the longitude of the portion F2 where the longitude φ is the largest is φ2, the radius r is ((φ2−φ1) / 2). . On the other hand, when the longitude φ of the central meridian M is φ3, the intersection width w is (φ3−φ1). Therefore, the ratio R is calculated by the following equation.
R = ((φ3-φ1) / (φ2-φ1)) 200
When the center meridian M passes on the right side of the center of the support pin S, the ratio R is calculated by the following equation.
R = ((φ2-φ3) / (φ2-φ1)) 200
[0026]
In each of the upper mold U and the lower mold L, the number of intermediate vent pins S, F, and f that intersects or contacts the central meridian M is preferably 6 or more and 18 or less. When the number is less than the above range, air remains easily. In this respect, the number is more preferably eight or more. If the number exceeds the above range, the structure of the mold 1 becomes complicated. In this respect, the number is more preferably equal to or less than 15.
[0027]
All of the intermediate vent pins that intersect or contact the central meridian M may be support pins, and all of the intermediate vent pins that intersect or contact the central meridian M may be fixed pins. When the support pin advances, the tip of the support pin projects from the cavity surface 3 and may hinder the flow of the molten resin composition. Flow inhibition causes uneven thickness of the cover. If the flow is blocked on the weld line, air tends to remain. From the viewpoint of residual suppression, it is preferable that all of the intermediate vent pins that intersect or contact the central meridian M are fixed pins. In the mold shown in FIG. 2, since all of the intermediate vent pins that intersect or contact the central meridian M are fixed pins F and f, flow inhibition is suppressed.
[0028]
On the other hand, when all of the intermediate vent pins that intersect or contact the central meridian M are fixing pins, it is necessary to provide support pins separately from these fixing pins, and the structure of the mold 1 becomes complicated. From the viewpoint of economy, it is preferable that both the support pin and the fixing pin are provided as intermediate vent pins that intersect or contact the central meridian M. In each of the upper mold U and the lower mold L, the number of intermediate vent pins intersecting or contacting the central meridian M is 6 or more and 18 or less, and the number of fixing pins intersecting or contacting the central meridian M is 3 It is preferable that the number is not less than 10 and not more than 10 and that the number of support pins intersecting with or contacting the central meridian M is not less than 3 and not more than 8. From the viewpoint that manufacturing of the molding die 1 is easy, it is more preferable that the number of the fixing pins that intersect or contact the central meridian M is six or less. From the viewpoint that the flow of the molten resin composition is not easily inhibited, the number of support pins that intersect or contact the center meridian M is more preferably four or less.
[0029]
As described above, the latitude θ of the center of the intermediate vent pins S, F, and f is not less than 45 ° and not more than 85 °. If the latitude θ is less than the above range, the clearance will be closed at the beginning of the injection of the molten resin composition. In this respect, the latitude θ is more preferably equal to or greater than 50 °, further preferably equal to or greater than 52 °, and particularly preferably equal to or greater than 60 °. If the latitude θ exceeds the above range, air remains easily when the gate balance is lost. In this respect, the latitude θ is more preferably equal to or less than 83 °, more preferably equal to or less than 80 °, and particularly preferably equal to or less than 79 °.
[0030]
The clearance between the intermediate vent pins S, F, and f (half the difference between the inner diameter of the pin hole and the outer diameter of the pin) is preferably 5 μm or more and 100 μm or less. If the clearance is less than the above range, it is difficult to discharge air. In this respect, the clearance is more preferably equal to or greater than 10 μm. If the clearance exceeds the above range, large burrs are likely to occur. In this respect, the clearance is more preferably equal to or less than 50 μm, and particularly preferably equal to or less than 40 μm.
[0031]
The number of gates G in each of the upper mold U and the lower mold L is preferably 4 or more and 16 or less. If the number of gates G is less than the above range, the thickness of the cover tends to be uneven. In this respect, the number of gates G is more preferably six or more. If the number of gates G exceeds the above range, the structure of the mold 1 becomes complicated. In this respect, the number of gates G is preferably equal to or less than 12, more preferably equal to or less than 10, and particularly preferably equal to or less than 8.
[0032]
This mold 1 is suitable for molding a cover having a small thickness. Specifically, it is suitable for molding a cover having a thickness of 0.3 mm or more and 1.4 mm or less. The cover is usually based on an ionomer resin or a thermoplastic elastomer. Specific examples of the thermoplastic elastomer include a thermoplastic polyurethane elastomer, a thermoplastic styrene elastomer, a thermoplastic polyamide elastomer, and a thermoplastic polyester elastomer. In particular, it is preferable that the cover contains an ionomer resin or a thermoplastic polyurethane elastomer. When an ionomer resin, a thermoplastic polyurethane elastomer or a mixture thereof is used, the ratio of the total amount of the ionomer resin and the thermoplastic polyurethane elastomer to the total base polymer is preferably 50% by mass or more, more preferably 75% by mass or more, 90% by mass or more is particularly preferred.
[0033]
The mold according to the present invention can also be used for molding an inner cover of a golf ball having two or more layers of covers. When the inner cover is molded, no pimples are provided on the cavity surface. When the inner cover is molded, the tips of all the vent pins P, S, F, and f are flat. The mold according to the present invention can also be used for molding a cover made of a rubber composition.
[0034]
FIG. 4 is a plan view showing a lower mold L of a molding die according to another embodiment of the present invention. The bottom view of the upper mold U has a shape in which FIG. 4 is turned upside down. Each of the upper mold U and the lower mold L has six gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 60 °. Each of the upper mold U and the lower mold L has six central meridians M. The longitude difference between adjacent center meridians M is 60 °. Each of the upper mold U and the lower mold L includes one pole vent pin P, three support pins S, three first fixing pins F, and three second fixing pins f. The support pin S, the first fixing pin F, and the second fixing pin f are all intermediate vent pins. As is clear from FIG. 4, on one central meridian M, there is at least one intermediate vent pin S, F, f. In other words, all central meridians M intersect or touch the intermediate vent pins S, F, f. The number of support pins S existing on the central meridian M is zero. The number of the fixing pins F and f existing on the central meridian M is six. In this molding die, the first fixing pin F and the second fixing pin f suppress the residual air.
[0035]
FIG. 5 is a plan view showing a lower mold L of a molding die according to still another embodiment of the present invention. The bottom view of the upper mold U has a shape in which FIG. 5 is turned upside down. Each of the upper mold U and the lower mold L has six gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 60 °. Each of the upper mold U and the lower mold L has six central meridians M. The longitude difference between adjacent center meridians M is 60 °. Each of the upper mold U and the lower mold L includes one pole vent pin P, three support pins S, and three first fixing pins F. Each of the support pin S and the first fixing pin F is an intermediate vent pin. As is clear from FIG. 5, on one central meridian M, at least one intermediate vent pin S, F exists. In other words, all central meridians M intersect or touch the intermediate vent pins S, F. The number of the support pins S existing on the central meridian M is three. The number of the first fixing pins F existing on the central meridian M is three. In this molding die, the residual air is suppressed by the support pin S and the first fixing pin F.
[0036]
FIG. 6 is a plan view showing a lower mold L of a molding die according to still another embodiment of the present invention. The bottom view of the upper mold U is equivalent to FIG. Each of the upper mold U and the lower mold L has eight gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 45 °. Each of the upper mold U and the lower mold L has eight central meridians M. The longitude difference between adjacent center meridians M is 45 °. Each of the upper mold U and the lower mold L includes one pole vent pin P, four support pins S, and eight first fixing pins F. Each of the support pin S and the first fixing pin F is an intermediate vent pin. As is clear from FIG. 6, on one central meridian M, at least one intermediate vent pin S, F exists. In other words, all central meridians M intersect or touch the intermediate vent pins S, F. The number of support pins S existing on the central meridian M is zero. The number of the first fixing pins F existing on the central meridian M is eight. In this mold, the first fixing pins F suppress the air from remaining.
[0037]
FIG. 7 is a plan view showing a lower mold L of a molding die according to still another embodiment of the present invention. The bottom view of the upper mold U has a shape in which FIG. 7 is turned upside down. Each of the upper mold U and the lower mold L has six gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 60 °. Each of the upper mold U and the lower mold L has six central meridians M. The longitude difference between adjacent center meridians M is 60 °. Each of the upper mold U and the lower mold L includes one pole vent pin P, three support pins S, and three first fixing pins F. Each of the support pin S and the first fixing pin F is an intermediate vent pin. As is clear from FIG. 7, at least one intermediate vent pin S, F exists on one central meridian M. In other words, all central meridians M intersect or touch the intermediate vent pins S, F. The number of the support pins S existing on the central meridian M is three. The number of the first fixing pins F existing on the central meridian M is three. In this molding die, the residual air is suppressed by the support pin S and the first fixing pin F.
[0038]
FIG. 8 is a plan view showing a lower mold L of a molding die according to still another embodiment of the present invention. The bottom view of the upper mold U has a shape in which FIG. 8 is turned upside down. Each of the upper mold U and the lower mold L has ten gates G. These gates G are arranged at equal intervals. The longitude difference between adjacent gates G is 36 °. Each of the upper mold U and the lower mold L has ten central meridians M. The longitude difference between adjacent center meridians M is 60 °. Each of the upper mold U and the lower mold L includes one pole vent pin P, five support pins S, and five first fixing pins F. Each of the support pin S and the first fixing pin F is an intermediate vent pin. The tip of the pole vent pin P is convex, and the tip forms a dimple. As is clear from FIG. 8, on one central meridian M, at least one intermediate vent pin S, F exists. In other words, all central meridians M intersect or touch the intermediate vent pins S, F. The number of the support pins S existing on the central meridian M is five. The number of the first fixing pins F existing on the central meridian M is five. In this molding die, the residual air is suppressed by the support pin S and the first fixing pin F.
[0039]
【Example】
Hereinafter, the effects of the present invention will be clarified based on examples, but the present invention should not be construed as being limited based on the description of the examples.
[0040]
[Preparation of cover material]
Type A and type B cover materials shown in Table 1 below were prepared.
[0041]
[Table 1]

[0042]
[Example 1]
A solid core having a diameter of 41.1 mm was charged into the mold shown in FIG. 2, and a type A cover material was injected around the core to obtain a golf ball. The cover thickness of this golf ball was 0.8 mm.
[0043]
[Examples 2 and 8]
A golf ball was obtained in the same manner as in Example 1 except that the diameter of the core was changed. The thickness of the cover is shown in Tables 2 and 3 below.
[0044]
[Examples 3 to 7 and Comparative Example 1]
A golf ball was obtained in the same manner as in Example 1, except that the molding dies shown in Tables 2 and 3 below were used. In the mold used in Comparative Example 1, there is no intermediate vent pin above the central meridian M as shown in FIG.
[0045]
[Example 9]
A golf ball was obtained in the same manner as in Example 1 except that the type B cover material was used.
[0046]
[Count of failure occurrences]
Golf balls shown in Tables 2 and 3 below were prepared, and the number of bears, air bites, and weld marks were visually counted. The results are shown in Tables 2 and 3 below.
[0047]
[Measurement of uneven thickness]
The golf ball was inspected by X-ray, and the maximum and minimum portions of the cover thickness were specified. The value obtained by subtracting the thickness of the minimum portion from the thickness of the maximum portion was defined as the thickness unevenness. Tables 2 and 3 below show the average values of the thickness unevenness obtained for 100 golf balls.
[0048]
[Table 2]

[0049]
[Table 3]

[0050]
In Tables 2 and 3, in the mold of Comparative Example 1 in which the intermediate vent pin does not exist on the central meridian, the defective rate is high. In the molding die of Example 7 in which five support pins exist on the central meridian, a bear is easily generated and uneven thickness is easily generated. This is presumably because the support pins hinder the flow of the molten resin composition. Further, in the mold of Example 4 in which the latitude of the first fixing pin is large, air biting and weld marks are slightly generated. This is presumed to be due to the difficulty in discharging the remaining air when the clearance of the pole vent pin is closed.
[0051]
【The invention's effect】
As described above, air is easily discharged in the mold of the present invention. With this mold, a high-quality golf ball can be obtained. The production method using this mold has a high yield.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a golf ball mold according to one embodiment of the present invention.
FIG. 2 is a plan view showing a lower mold of the mold of FIG. 1;
FIG. 3 is an enlarged view showing a part of the lower mold of FIG. 2;
FIG. 4 is a plan view showing a lower mold of a molding die according to another embodiment of the present invention.
FIG. 5 is a plan view showing a lower mold of a molding die according to still another embodiment of the present invention.
FIG. 6 is a plan view showing a lower mold of a molding die according to still another embodiment of the present invention.
FIG. 7 is a plan view showing a lower mold of a molding die according to still another embodiment of the present invention.
FIG. 8 is a plan view showing a lower mold of a molding die according to still another embodiment of the present invention.
FIG. 9 is a plan view showing a lower mold of a molding die according to Comparative Example 1 of the present invention.
[Explanation of symbols]
1. Mold for golf ball
3 ... Cavity surface
5 ... pimples
7 ・ ・ ・ Parting line
9, 11, 13 ... pin hole
f: Second fixed pin
F: First fixed pin
G ・ ・ ・ Gate
L: Lower mold
M: Central meridian
P ・ ・ ・ Vent pin
S: Support pin
U ・ ・ ・ Upper type

Claims (7)

Consists of an upper mold and a lower mold,
A substantially spherical cavity, a plurality of gates through which the polymer composition injected into the cavity passes, and a plurality of intermediate vent pins having a center θ of 45 ° or more and 85 ° or less,
When a meridian having a center value between the longitude φ of one gate and the longitude φ of another gate adjacent to this gate is set as a center meridian, all the centers existing on the cavity surface in each of the upper mold and the lower mold. A mold for golf balls whose meridian crosses or touches an intermediate vent pin. 2. The upper mold and the lower mold each having a central meridian that intersects the intermediate vent pin, and a ratio R of the intersection width to the radius of the intermediate vent pin is 50% or more in longitude conversion. 3. Mold. The molding die according to claim 1, wherein the number of intermediate vent pins intersecting or contacting the center meridian is 6 or more and 18 or less in each of the upper mold and the lower mold. The mold according to claim 3, wherein all of the intermediate vent pins that intersect or contact the center meridian are fixed pins. The intermediate vent pin that intersects or contacts the center meridian includes a fixing pin and a support pin that is capable of moving back and forth with respect to the cavity. The molding die according to claim 3, wherein the number is 3 or more and 8 or less, and the number of the fixing pins which intersects or contacts the central meridian is 3 or more and 10 or less. The mold according to claim 5, wherein the number of the support pins intersecting with or contacting the center meridian is three or four. It comprises an upper mold and a lower mold, a substantially spherical cavity, a plurality of gates, and a plurality of intermediate vent pins whose central latitude θ is 45 ° or more and 85 ° or less, and the longitude of one gate When a meridian having a center value between φ and the longitude φ of another gate adjacent to this gate is taken as a center meridian, in each of the upper mold and the lower mold, all the center meridians existing on the cavity surface are regarded as intermediate vent pins. A step in which the core is put into a crossing or contacting mold,
Injecting the polymer composition into the cavity through the gate while discharging air existing in the cavity from the clearance of the intermediate vent pin.

Images