JP2003266440A - Molding tool for golf ball and manufacturing method for golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding tool for a golf ball from which air is easily discharged. <P>SOLUTION: The molding tool is equipped with a holding pin 7. The holding pin 7 has notch parts 19 provided in the outer peripheral surface thereof and extending longitudinally. The upper end of the notch part 19 is positioned slightly lower than the upper end of the holding pin 7. The sectional shape of the holding pin 7 is circular above the upper end of the notch part 19. Above the upper end of the notch part 19, a clearance between the holding pin 7 and a holding pin hole 15 is narrow, while a clearance between the holding pin hole 15 and the notch part 19 is wide. A molten polymer composition is filled around a core held at the center of a cavity by the holding pin 7 and thereby a cover constituted of this polymer composition is molded. On the occasion, the air being present between the surface of the cavity and the core is discharged outside the molding tool through the clearance between the holding pin hole 15 and the notch part 19. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball mold and a golf ball manufacturing method. More particularly, the present invention relates to improvements in molds used to mold golf ball covers.

[0002]

2. Description of the Related Art A golf ball, depending on its structure, is a one-piece golf ball, a two-piece golf ball, a multi-piece golf ball (having a three or more layer structure),
It is classified as a thread-wound golf ball or the like.

A two-piece golf ball is composed of a core and a cover that covers the surface of the core. A mold having a spherical cavity is used for manufacturing a two-piece golf ball. This mold has a holding pin that can advance and retreat with respect to the cavity, and a vent pin that communicates the cavity with the outside air. The advanced retaining pin retains the core in the center of the cavity.
Then, the resin composition is put into an injection molding machine, melted, and injected toward the cavity. The molten resin composition is filled in the gap between the cavity surface and the core. This molten resin composition coats around the core and is then solidified to form a cover.

At the stage when the core is held by the holding pin, air is present in the gap between the cavity surface and the core. As the molten resin composition flows into the cavity, the air in the cavity is discharged to the outside. The discharge is performed from the clearance of the holding pin and the vent pin.

The molten resin composition may flow into the clearance, and the molten resin composition may form fins. Oversized fins reduce the appearance of the golf ball. From the viewpoint of suppressing fins, the clearance needs to be as small as possible. Normally clearance is
It is set to 0.01 mm to 0.05 mm.

Since the clearance is narrow as described above, the discharge of air may be insufficient. If the discharge is insufficient, bare (space due to residual air), air entering the cover, burning (burning on the cover), weld mark (line-shaped mark at the joint between resin compositions), etc. Defects occur. In particular, when the flow rate of the molten resin composition is high, air is likely to be insufficiently discharged. In recent years, golf balls provided with a cover having a small thickness have been developed and put on the market. In molding the cover of this golf ball, it is necessary to fill the molten resin composition at a high speed, which causes a problem of poor air discharge.

Japanese Unexamined Patent Publication No. 2000-37480 discloses a technique in which a holding pin is made of a porous material to enhance the air discharging property. This retaining pin causes clogging of the hole with repeated use. This retaining pin is expensive. Moreover, this holding pin is fragile and easily damaged. Retaining pins made of porous material are not practical.

[0008]

As described above, in a mold in which fins are heavily weighted, air ejection failure is likely to occur. On the other hand, fins are likely to be formed in a mold having a large clearance for the purpose of smoothly discharging air.
The poor ejection and the generation of fins deteriorate the quality of the golf ball.

The present invention has been made in view of such circumstances, and an object thereof is to provide a mold for a golf ball in which air is easily discharged. Another object of the present invention is to provide a manufacturing method capable of obtaining a high quality golf ball.

[0010]

A golf ball molding die according to the present invention comprises a holding pin. This holding pin has a notch portion extending in the longitudinal direction on its outer peripheral surface. The upper end of this cutout is located below the upper end of the holding pin. The holding pin can move back and forth with respect to the spherical cavity. By filling the molten polymer composition around the core held in the center of the cavity by the holding pin, a cover made of the polymer composition is molded.
At the time of filling, the air in the cavity is discharged to the outside through the notch. Therefore, even if the clearance near the upper end of the holding pin is small, defective discharge of air is unlikely to occur. Since there is no notch near the top of the holding pin,
Generation of fins is suppressed. By using this golf ball mold, the quality of the golf ball can be improved.

Instead of the notch or together with the notch, a groove extending in the circumferential direction may be formed on the outer peripheral surface of the holding pin. In this golf ball mold, the air in the cavity is discharged to the outside through the groove. This golf ball mold is excellent in air discharge.

A molding die for a golf ball according to another invention is
A holding pin that can move forward and backward with respect to the spherical cavity and a vent pin are provided. This vent pin has a notch portion extending in the longitudinal direction on its outer peripheral surface. The upper end of this cutout is located below the upper end of the vent pin. By filling the molten polymer composition around the core held in the center of the cavity by the holding pin, a cover made of the polymer composition is molded. At the time of filling, the air in the cavity is discharged to the outside through the cutout portion of the vent pin. Therefore, even if the clearance near the upper end of the vent pin is small, defective discharge of air is unlikely to occur. Since there is no notch near the upper end of the vent pin, generation of fins is suppressed. By using this golf ball mold, the quality of the golf ball can be improved.

Instead of the notch or together with the notch, a groove extending in the circumferential direction may be formed on the outer peripheral surface of the vent pin. In this golf ball mold, the air in the cavity is discharged to the outside through the groove of the vent pin. This golf ball mold is excellent in air discharge.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, with reference to the drawings,
The present invention will be explained in detail based on the preferred embodiments.

FIG. 1 is a partial sectional view showing a golf ball molding die 1 (hereinafter referred to as "molding die") according to an embodiment of the present invention. The molding die 1 includes an upper die 3, a lower die 5, a plurality of holding pins 7 and two vent pins 9. The holding pin 7 is located equidistant from the pole in each of the upper die 3 and the lower die 5. In each of the upper mold 3 and the lower mold 5, the holding pins 7 are 3 to 8
Books, in particular 3 to 6, are provided. In FIG. 1, the upper mold 3
Two holding pins 7 are shown in each of the lower mold 5 and the lower mold 5. The vent pin 9 is located at the pole of the upper die 3 and the pole of the lower die 5.

The upper die 3 and the lower die 5 have a body 11, a cavity surface 13, a holding pin hole 15, and a vent pin hole 17.
It has and. The cavity surface 13 has a hemispherical shape.
When the mold 1 is tightened, as shown in FIG.
A spherical cavity is formed by the cavity surface 13 and the cavity surface 13 of the lower mold 5. The holding pin hole 15 and the vent pin hole 17 penetrate the body 11 from the outside toward the spherical cavity. The cross-sectional shapes of the inner peripheral surfaces of the holding pin hole 15 and the vent pin hole 17 are circular. Although not shown, a large number of protrusions are formed on the cavity surface 13. At the time of molding the cover, the projection forms a dimple having a shape that is the inverse of the shape of the projection.

FIG. 2A shows a holding pin 7 of the molding die 1 shown in FIG.
FIG. 2B is an enlarged front view showing a part of FIG.
It is sectional drawing which followed the BB line of (a), and FIG.2 (c) is sectional drawing which followed the CC line of FIG.2 (a). The holding pin 7 has a notch 19 extending in the longitudinal direction (vertical direction in FIG. 2A) on its outer peripheral surface. The upper end of the cutout portion 19 is located slightly below the upper end of the holding pin 7.
The notch 19 is formed by scraping off the outer peripheral surface of the cylindrical base material to form a flat surface. In this example, the number of notches 19 is four. A curved portion 21 is provided between the adjacent notched portions 19 on the outer peripheral surface.

The width (circumferential dimension) of the notch 19 is 0.3.
mm or more is preferable. If the width is less than the above range, the air discharging property may be insufficient. From this viewpoint, the width is more preferably 0.5 mm or more, and particularly preferably 1 mm or more. The width is usually 3.0 mm or less.

The depth of the notch 19 (radial dimension) is
0.02 mm or more is preferable. If the depth is less than the above range, the air discharging property may be insufficient. From this viewpoint, the depth is more preferably 0.03 mm or more, and 0.
A thickness of 05 mm or more is particularly preferable. Depth is usually 1.0 mm
It is considered as follows.

As is apparent from FIG. 2 (b), the notch 1
Above the upper end of 9, the holding pin 7 has a circular cross-sectional shape. The diameter of this circle is usually 2 mm or more and 6 mm or less,
Furthermore, 2.5 mm or more and 5 mm or less, especially 2.5 mm
It is 4 mm or less. The holding pin hole 15 is shown by a chain double-dashed line in FIG. Holding pin 7
The clearance between the vicinity of the upper end and the holding pin hole 15 is 0.
It is preferably 005 mm or more and 0.10 mm or less. If the clearance is less than the above range, the air discharging property may be insufficient, and the holding pin 7 may not be able to move back and forth. From this viewpoint, the clearance is more preferably 0.010 mm or more, and particularly preferably 0.020 mm or more.
If the clearance exceeds the above range, the molten resin composition may flow into the clearance to form large fins. From this viewpoint, the clearance is more preferably 0.075 mm or less, further preferably 0.05 mm or less,
It is particularly preferably 0.03 mm or less.

The holding pin hole 15 is also shown in FIG. 2 (c). The clearance between the holding pin hole 15 and the curved portion 21 is equivalent to the clearance between the vicinity of the upper end of the holding pin 7 and the holding pin hole 15 shown in FIG. The clearance between the holding pin hole 15 and the cutout portion 19 is larger than the clearance between the holding pin hole 15 and the curved portion 21.
The ratio of the maximum clearance between the holding pin hole 15 and the cutout portion 19 to the clearance between the holding pin hole 15 and the curved portion 21 is preferably 110% or more. If the ratio is less than the above range, the air discharging property may be insufficient. From this viewpoint, the ratio is more preferably 150% or more, and particularly preferably 200% or more. The ratio is usually 500
It is set to 0% or less.

A convex portion 23 is formed at the front end of the holding pin 7. At the time of molding the cover, the convex portion 23 forms a dimple having a shape in which the shape of the convex portion 23 is reversed. When the front end of the holding pin contacts the land portion (a portion of the golf ball surface other than the dimples), the convex portion 23 is not provided. In this case, the front end of the holding pin has an inclined flat surface.

FIG. 3 (a) is an enlarged front view showing the vent pin 9 of the mold 1 of FIG. 1, FIG. 3 (b) is a bottom view thereof, and FIG. 3 (c) is FIG. 3 (a). ) Is a cross-sectional view taken along the line C-C in FIG. 3D, and FIG. 3D is a cross-sectional view taken along the line D-D in FIG. The vent pin 9 has a flange 25,
The rear groove portion 27, the body portion 29, the front groove portion 31, the front end portion 33, and the cutout portion 35 are provided. The front groove portion 31 and the rear groove portion 27 are formed by scraping off the surface of the cylindrical base material in the circumferential direction. The cutout portion 35 extends from the front groove portion 31 through the rear groove portion 27 to the lower surface of the flange 25. There are four notches 35. A curved portion 37 is provided between the adjacent notches 35 on the outer peripheral surface of the body portion 29.

The width (circumferential dimension) of the notch 35 is 0.3.
mm or more is preferable. If the width is less than the above range, the air discharging property may be insufficient. From this viewpoint, the width is more preferably 0.5 mm or more, and particularly preferably 0.7 mm or more. The width is usually 2.0 mm or less.

The depth (radial dimension) of the notch 35 is
It is preferably 0.05 mm or more. If the depth is less than the above range, the air discharging property may be insufficient. From this viewpoint, the depth is more preferably 0.1 mm or more, and is 0.3
mm or more is particularly preferable. The depth is usually 1.0 mm or less.

The width (longitudinal dimension) of the front groove portion 31 and the rear groove portion 27 is preferably 0.2 mm or more. If the width is less than the above range, the air discharging property may be insufficient. From this viewpoint, the width is more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. Width is usually 1.0
mm or less.

The depth (radial dimension) of the front groove portion 31 and the rear groove portion 27 is preferably 0.05 mm or more. If the depth is less than the above range, the air discharging property may be insufficient. From this viewpoint, the depth is more preferably 0.1 mm or more, and particularly preferably 0.3 mm or more. The depth is usually 1.0 mm or less.

As is apparent from FIG. 3 (c), the front end portion 3
The cross-sectional shape of 3 is a circle. What is indicated by a chain double-dashed line in FIG. 3C is the vent pin hole 17. The clearance between the front end portion 33 and the vent pin hole 17 is 0.00
It is preferably 5 mm or more and 0.10 mm or less. If the clearance is less than the above range, the air discharging property may be insufficient. From this viewpoint, the clearance is 0.010.
mm or more is more preferable, and 0.015 mm or more is particularly preferable. If the clearance exceeds the above range, the molten resin composition may flow into the clearance to form large fins. From this point of view, the clearance is 0.07m
m or less is more preferable, 0.05 mm or less is further preferable, and 0.03 mm or less is particularly preferable.

The vent pin hole 17 is also shown in FIG. 3 (d). The clearance between the vent pin hole 17 and the curved portion 37 is equal to the clearance between the front end portion 33 and the vent pin hole 17 shown in FIG. The clearance between the vent pin hole 17 and the cutout portion 35 is larger than the clearance between the vent pin hole 17 and the curved portion 37.
The ratio of the maximum clearance between the vent pin hole 17 and the cutout portion 35 to the clearance between the vent pin hole 17 and the curved portion 37 is preferably 110% or more. If the ratio is less than the above range, the air discharging property may be insufficient. From this viewpoint, the ratio is more preferably 150% or more, and particularly preferably 200% or more. The ratio is usually 50
It is set to less than 00%.

A convex portion 39 is formed on the front end portion 33. At the time of molding the cover, the convex portions 39 are used to form the convex portions 3.
A dimple having a shape obtained by inverting the shape of 9 is formed. When the front end of the vent pin contacts the land portion, the convex portion 39 is not provided. In this case, the front end of the vent pin has a flat surface.

The clearance between the front groove 31 and the vent pin hole 17 and the clearance between the rear groove 27 and the vent pin hole 17 are usually 0.1 mm or more and 2 mm or less. The front groove portion 31 and the rear groove portion 27 are formed over the entire circumference, but the groove portions may be partially formed. It is not necessary for all of the rear groove portion 27, the front groove portion 31, and the cutout portion 35 to be provided. By providing any of these, the air discharging property is improved.

The shortest distance between the front groove portion 31 of the vent pin 9 and the cavity surface 13 is preferably 5 mm or less. If the shortest distance exceeds the above range, the air discharging property may be insufficient. From this viewpoint, the shortest distance is more preferably 3 mm or less, and particularly preferably 1 mm or less. The shortest distance is
Usually, it is set to 0.1 mm or more. When the front groove portion 31 is not provided, the front end of the cutout portion 35 and the cavity surface 1
The shortest distance to 3 is set within the above range.

FIG. 4 is an enlarged sectional view showing a part of the molding die 1 of FIG. When the cover is molded by the molding die 1, first, the core 41 is put into the cavity of the lower die 5. Next, the mold is clamped and the holding pin 7 advances. FIG. 4A shows a state in which the holding pin 7 has advanced. By the forward movement, the holding pin 7 holds the core 41. The core 41 is located at the center of the spherical cavity. Air is present between the cavity surface 13 and the core 41.

Next, the molten resin composition is gradually filled into the spherical cavity through a gate (not shown). With the filling, the air existing between the cavity surface 13 and the core 41 is gradually discharged to the outside. The discharge is performed from the clearance between the holding pin 7 and the holding pin hole 15. The holding pin 7 is formed with a cutout portion 19, and the clearance between the cutout portion 19 and the holding pin hole 15 is large, so that the discharge is smoothly performed. The discharge is also made from the clearance between the vent pin 9 and the vent pin hole 17. Since the front groove portion 31, the rear groove portion 27, and the cutout portion 35 are formed in the vent pin 9, air is smoothly discharged through these.

Immediately before the completion of filling the molten resin composition,
The holding pin 7 retracts. FIG. 4B shows a state in which the holding pin 7 is retracted. Although the holding pin 7 is separated from the core 41, a resin composition is not provided between the core 41 and the cavity surface 13 (not shown in FIG. 4B).
Exists, the core 41 hardly moves.
After the filling of the molten resin composition is completed, the mold 1 is opened and the golf ball is taken out.

Even when the holding pin 7 is most advanced, it is preferable that the front end of the cutout portion 19 be present inside the holding pin hole 15. As a result, friction between the stepped portion of the cutout portion 19 and the cavity surface 13 is prevented, wear of the holding pin 7 and the body 11 is suppressed, and inflow of the molten synthetic resin into the cutout portion 19 is prevented. The shortest distance between the front end of the cutout portion 19 and the cavity surface 13 when the holding pin 7 is most advanced is preferably 3 mm or less. If the shortest distance exceeds the above range, the air discharging property may be insufficient. From this viewpoint, the shortest distance is more preferably 1 mm or less,
0.5 mm or less is particularly preferable. The shortest distance is usually set to 0.05 mm or more.

From the viewpoint of air exhaustability, the number of the cutout portions 19 of the holding pin 7 and the cutout portions 35 of the vent pin 9 is preferably 1 or more, and particularly preferably 2 or more. From the viewpoint of easy processing, the number of the cutout portions 19 of the holding pin 7 and the cutout portions 35 of the vent pin 9 is preferably 8 or less, particularly preferably 4 or less.

In this mold 1, notches 19 and 35 are formed in both the holding pin 7 and the vent pin 9,
The notch 19 may be formed only in the holding pin 7, and the notch 35 may be formed only in the vent pin 9.

FIG. 5 (a) is a front view showing a part of the holding pin 43 of the golf ball mold according to another embodiment of the present invention, and FIG. 5 (b) is shown in FIG. 5 (a). 5B is a cross-sectional view taken along line BB of FIG. 5, FIG. 5C is a cross-sectional view taken along line CC of FIG. 5A, and FIG. 5D is D of FIG. 5A. −
It is sectional drawing which followed the D line. The holding pin 43 has four notches 45 and one groove 47. The structure of the part of the mold except the holding pin 43 is the same as that of the mold 1 shown in FIG.

The notch portion 45 extends in the longitudinal direction (vertical direction in FIG. 5A). The upper end of the cutout portion 45 is continuous with the groove portion 47. Notch 4 (not shown)
The lower end of 5 extends to the outside of the body 11. A curved portion 49 is provided between the adjacent notched portions 45 on the outer peripheral surface. The size of the cutout portion 45 is the same as that of the cutout portion 19 of the holding pin 7 shown in FIG.

The width (dimension in the longitudinal direction) of the groove portion 47 is 0.2.
mm or more is preferable. If the width is less than the above range, the air discharging property may be insufficient. From this viewpoint, the width is more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. The width is usually 10.0 mm or less.

The depth (radial dimension) of the groove portion 47 is 0.
It is preferably at least 05 mm. If the depth is less than the above range, the air discharging property may be insufficient. From this viewpoint, the depth is more preferably 0.1 mm or more, and 0.3 m
m or more is particularly preferable. The depth is usually 1.0 mm or less.

As is apparent from FIG. 5B, the groove 47
Above that, the cross-sectional shape of the holding pin 43 is a circle.
The holding pin hole 15 is shown by a chain double-dashed line in FIG. The clearance between the upper end of the holding pin 43 and the holding pin hole 15 is 0.005 mm or more and 0.1
It is preferably 0 mm or less. If the clearance is less than the above range, the air discharging property becomes insufficient and the holding pin 4
It may be impossible to move back and forth in 3. From this point of view, the clearance is more preferably 0.010 mm or more, and 0.
Particularly preferred is 020 mm or more. If the clearance exceeds the above range, the molten resin composition may flow into the clearance to form large fins. From this viewpoint, the clearance is more preferably 0.07 mm or less, and 0.0
5 mm or less is particularly preferable.

The holding pin hole 15 is also shown in FIG. 5 (c). The clearance between the holding pin hole 15 and the groove portion 47 is extremely large. Clearance is usually 0.1m
It is set to m or more and 2 mm or less. In this example, the groove portion 47 is formed over the entire circumference, but the groove portion may be partially formed.

The holding pin hole 15 is also shown in FIG. 5 (d). The clearance between the holding pin hole 15 and the curved portion 49 is equal to the clearance between the vicinity of the upper end of the holding pin 43 and the holding pin hole 15 shown in FIG. 5B.
The clearance between the holding pin hole 15 and the cutout portion 45 is larger than the clearance between the holding pin hole 15 and the curved portion 49. The ratio of the maximum clearance between the holding pin hole 15 and the cutout portion 45 to the clearance between the holding pin hole 15 and the curved portion 49 is preferably 110% or more. If the ratio is less than the above range, the air discharging property may be insufficient. From this viewpoint, the ratio is more preferably 150% or more, and particularly preferably 200% or more. The ratio is usually 50
It is set to less than 00%.

Also in this holding pin 43, the air existing between the cavity surface 13 and the core 41 is gradually discharged to the outside as the molten resin composition is filled. The discharge is performed from the clearance between the holding pin 43 and the holding pin hole 15. Since the groove portion 47 and the cutout portion 45 are formed in the holding pin 43, the discharge is smoothly performed.

Even when the holding pin 43 is most advanced, it is preferable that the groove portion 47 exists inside the holding pin hole 15. As a result, friction between the groove portion 47 and the cavity surface 13 is prevented, wear of the holding pin 43 and the body 11 is suppressed, and in addition, the molten synthetic resin is prevented from flowing into the groove portion 47. Groove portion 47 when holding pin 43 is most advanced
The shortest distance between the cavity surface 13 and the cavity surface 13 is preferably 5 mm or less. If the shortest distance exceeds the above range, the air discharging property may be insufficient. From this viewpoint, the shortest distance is 3
mm or less is more preferable, and 1 mm or less is particularly preferable.
The shortest distance is usually set to 0.1 mm or more.

[0048]

The effects of the present invention will be clarified by the following examples, but the present invention should not be construed in a limited way based on the description of the examples.

[Example 1] 5 for each of the upper die and the lower die
A mold having a holding pin for each and a vent pin for each was prepared. The retaining pin is of the type shown in FIG. 2 and has a cutout. The vent pin is of the type shown in FIG. 3 and has a notch, a front groove and a rear groove. A core made of solid rubber and having a diameter of 39.5 mm was placed in the cavity of this mold. While holding this core with a holding pin, a resin composition composed of an ionomer resin and titanium dioxide was injected between the core and the cavity surface to form a golf ball having a diameter of 42.7 mm.

[Examples 2 to 5 and Comparative Example] Golf balls were obtained in the same manner as in Example 1 except that the specifications of the holding pin and the vent pin were as shown in Table 1 below. The holding pin used in Example 5 and the comparative example is a conventional type, and its front view is shown in FIG. Examples 3 and 4
The vent pin used in the comparative example is of a conventional type, and its front view is shown in FIG.

[Calculation of Defective Rate] 100 golf balls of each of the examples and comparative examples were visually observed to calculate the defective rate of appearance. All the defects were weld marks. The results are shown in Table 1 below.

[0052]

[Table 1]

In Table 1, the defective rate of the manufacturing method of each example is lower than the defective rate of the manufacturing method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

The present invention has been described in detail above with the case where the cover of the two-piece golf ball is molded as an example.
The mold of the present invention is also suitable for molding an inner cover of a golf ball having an inner cover and an outer cover. The mold of the present invention is also suitable for molding a cover made of a polymer composition (for example, a rubber composition) other than the resin composition.

[0055]

As described above, the molding die of the present invention is excellent in air discharge. By using this mold, a high quality golf ball can be manufactured.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a mold for a golf ball according to an embodiment of the present invention.

2 (a) is an enlarged front view showing a part of a holding pin of the molding die of FIG. 1, and FIG. 2 (b) is taken along line BB of FIG. 2 (a). FIG. 2C is a sectional view, and FIG.
It is sectional drawing which followed CC line | wire of (a).

3 (a) is an enlarged front view showing a vent pin of the mold of FIG. 1, FIG. 3 (b) is a bottom view thereof, and FIG. 3 (c) is FIG. 3 (a). 3D is a cross-sectional view taken along line CC of FIG. 3, and FIG. 3D is a cross-sectional view taken along line DD of FIG.

FIG. 4 is an enlarged cross-sectional view showing a part of the mold of FIG.

FIG. 5 (a) is a front view showing a part of a holding pin of a mold for a golf ball according to another embodiment of the present invention, and FIG. 5 (b) is FIG. 5 (a). 5B is a cross-sectional view taken along line BB of FIG. 5, FIG. 5C is a cross-sectional view taken along line CC of FIG. 5A, and FIG. 5D is D of FIG. 5A. It is sectional drawing which followed the -D line.

FIG. 6 is a front view showing a part of a conventional holding pin.

FIG. 7 is a front view showing a conventional vent pin.

[Explanation of symbols]

1. Mold for golf ball (mold) 3 ... Upper mold 5 ... Lower mold 7, 43 ... Holding pin 9 ... Vent pin 11 ... Body 13 ... Cavity surface 15: Holding pin hole 17 ... Vent pin hole 19, 35, 45 ... Notch 21, 37, 49 ... Curved part 23, 39 ... Convex part 25 ... Flange 27 ... rear groove 29 ... Body 31 ... Front groove 33 ... Front end 41 ... Core 47 ... Groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Haruki Shinagawa             3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo               Sumitomo Rubber Industries, Ltd. F-term (reference) 4F202 AA45 AD18 AD20 AG03 AG19                       AH61 CA11 CA30 CB01 CB12                       CB17 CK52 CP01 CP04 CQ03                       CQ05                 4F206 JA07 JB12 JB17 JF05 JF46                       JL02 JQ03 JQ81

Claims (5)

[Claims] 1. A spherical cavity and a holding pin capable of advancing and retracting with respect to the cavity are provided, and a molten polymer composition is filled around a core held in the center of the cavity by the holding pin. A mold for a golf ball, in which a cover made of a polymer composition is molded, wherein the holding pin has a notch portion extending in the longitudinal direction on its outer peripheral surface, and the upper end of the notch portion is higher than the upper end of the holding pin. A molding die for a golf ball, which is also located below. 2. A spherical cavity and a holding pin capable of advancing and retracting with respect to the cavity, and the molten pin is filled with the molten polymer composition around a core held in the center of the cavity. A mold for a golf ball, in which a cover made of a polymer composition is molded, wherein the holding pin has a groove portion extending in the circumferential direction on its outer peripheral surface. 3. A spherical cavity, a holding pin capable of advancing and retracting with respect to the cavity, and a vent pin for communicating the cavity with the outside air. A mold for a golf ball, in which a cover made of the polymer composition is molded by filling the melted polymer composition into a mold, the vent pin having a notch extending in the longitudinal direction on its outer peripheral surface. The golf ball molding die is characterized in that the upper end of the notch is located below the upper end of the vent pin. 4. A spherical cavity, a holding pin capable of advancing and retreating with respect to the cavity, and a vent pin for communicating the cavity with the outside air. The holding pin surrounds a core held in the center of the cavity. A mold for a golf ball, in which a cover made of the polymer composition is molded by being filled with the molten polymer composition, wherein the vent pin has a groove portion extending in the circumferential direction on its outer peripheral surface. Mold for a golf ball, characterized by: 5. One of claims 1 to 4 above
A method of manufacturing a golf ball, which comprises a step of molding a cover around a core by using the golf ball molding die described in the item.