JP2000288126A - Manufacture of golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing golf ball capable of efficiently manufacturing golf balls in high quality, considerably reducing the eccentricity of an inner core. SOLUTION: A vulcanized inner core 9 is retained, with a spherical shell- shaped cavity to the inner surface of a cavity, in a transfer molding die 1 provided with an upper mold 3 and a lower mold 4 and having a pot part for retaining a specified quantity of unvulcanized rubber material 6, and the unvulcanized rubber material 6 in the pot part is filled in the spherical shell-shaped cavity. An unvulcanized rubber layer 13 is therefore laminated on the inner core 9 to transfer-mold a spherical intermediate product 14. The spherical intermediate product 14 is taken out of the transfer molding die 1 and charged in a vulcanization molding die to vulcanization-mold the unvulcanized rubber layer 13, thus forming core material or a golf ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a golf ball.

[0002]

2. Description of the Related Art Conventionally, the following method has been widely used for producing a core material of a multi-piece golf ball such as a two-layer core or a three-layer core. That is, as shown in FIG. 8A, a lower mold b in which a pair of halves a, a having a hemispherical recess c are connected at a hinge portion, and each hemispherical recess c of the lower mold b,
Each of the hemispherical concave portions c of the preforming mold having an upper mold f (dome type) having hemispherical convex portions e corresponding to.
The unvulcanized rubber material d is charged, and FIG. 8 (b) (c)
As shown in (d), the upper mold f is lowered and the upper mold f and the lower mold b are lowered.
Presses the rubber material d to form a hemispherical shell-shaped unvulcanized rubber layer g.

After that, as shown in FIG. 8 (e), a vulcanized inner core h is put on an unvulcanized rubber layer g formed in a hemispherical concave portion c of one half a. As shown in FIG. 8 (f) and FIG. 9 (a), the other half a is folded, overlapped with one half a, and pressed. Thus, as shown in FIG. 9B, the unvulcanized rubber layer g of the other half a is covered on the inner core h. That is, the inner core h is externally covered with a pair of unvulcanized rubber layers g, g to form a spherical intermediate product k. Thereafter, as shown in FIG. 9 (c), the ejectors m provided on the one half a side are actuated to take out the respective intermediate products k, and the vulcanization mold n shown in FIG. And the uncured rubber layer g of each intermediate product k ...
Are vulcanized to form a core material (not shown).

[0004]

However, in such a conventional manufacturing method, there is a problem that the inner core h moves due to the pressure at the time of covering, and the inner core h is largely eccentric. In addition, the bonding surface (seam) between the pair of unvulcanized rubber layers g bonded to the inner core h may be peeled off, resulting in a quality problem. In order to prevent the adhesive surface from peeling off,
Optimization of the temperature, mold clamping pressure, mold clamping time, etc. of the rubber material was tried, but this peeling could not be completely prevented.

Accordingly, an object of the present invention is to provide a method of manufacturing a golf ball which can greatly reduce the eccentricity of the inner core and can be manufactured with high quality and efficiency.

[0006]

In order to achieve the above object, a method of manufacturing a golf ball according to the present invention has a pot portion for holding a predetermined amount of an unvulcanized rubber material, and has an upper mold and a lower mold. The vulcanized inner core is held in a transfer molding die having a mold with a spherical shell-shaped gap between itself and the inner surface of the cavity, and the unvulcanized rubber material in the pot portion is filled in the spherical shell-shaped gap. Filling, transfer the spherical intermediate product by laminating an unvulcanized rubber layer on the inner core, and then take out the spherical intermediate product from the transfer molding die and put it into the vulcanization molding die. The unvulcanized rubber layer is vulcanized to form a core material or a golf ball.

Further, a plurality of hold pins projecting into the cavity of the transfer molding die are provided in the upper mold and the lower mold so as to be able to advance or retreat, and the inner core is formed by the plurality of hold pins. It has a spherical shell-shaped space between the inner surface and the inner surface.

The difference between the protrusion of the upper mold side hold pin projecting into the cavity and the protrusion of the lower mold side hold pin projecting into the cavity is 0.03 mm to 0.2 m.
It is set to m.

Further, the surface of the inner core held in the transfer molding die is polished in advance. Further, a runner portion communicating with a gate portion of a cavity of the transfer molding die is disposed inside one of the upper die and the lower die.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments.

FIG. 1 is a simplified explanatory view of a method of manufacturing a golf ball of the present invention. A transfer molding die 1 used in the present invention includes a compression extruding portion 2, an upper die 3, and a lower die 4. 1
As shown in (a), a predetermined amount of the unvulcanized rubber material 6 is
The resin is injected into the pot portion 5 above the upper die 3 through the injection hole 7 of the compression extrusion unit 2. (Note that the pot portion 5 may be fed by hand or a machine hand.) The pot portion 5 may be provided with a heating section such as a heater, and the rubber material 6 may be plasticized in the pot portion 5. In a plurality of (in this embodiment, nine as shown in FIG. 2) cavities 8 formed by the upper die 3 and the lower die 4 in the transfer molding die 1, the vulcanized inner core is formed. 9 is held with a spherical shell-shaped gap 10 between itself and the inner surface of the cavity 8.

Then, as shown in FIG. 1B, when the compression extrusion section 2 is lowered in the direction of arrow A, the unvulcanized rubber material 6 in the pot section 5 is distributed in the upper mold 3 in the vertical direction. A spherical intermediate product 14 in which an unvulcanized rubber layer 13 is laminated on the inner core 9 is formed by press-fitting into the spherical shell-shaped voids 10 through the provided supply flow channels 11 and the runner portions 12 arranged in the horizontal direction. Is done.

Then, as shown in FIG. 1 (c), the upper mold 3 is opened, the spherical intermediate products 14 are taken out of the transfer molding die 1, and then put into a vulcanizing die (not shown). The vulcanized rubber layer 13 is vulcanized and formed to form a core of a two-layer core.
Accordingly, there is no waste of the rubber material 6 and an extremely thin layer can be manufactured, the eccentricity of the inner core 9 can be greatly reduced, and a golf ball with particularly high dimensional accuracy can be manufactured.

FIG. 2 is a plan view showing the positional relationship between the supply passage 11 and the runner portion 12 of the rubber material 6 with respect to the cavity 8. A plurality of (16 in the present embodiment) cylindrical supply flow paths communicating with the pot portion 5 on the upper part of the upper die 3
Are arranged in the upper die 3 in the vertical direction, and communicate with the cylindrical runner portions 12 at the lower end thereof.

The runner portions 12 are arranged (in a grid) so as to communicate with a plurality of (in this embodiment, nine) cavities 8 from four sides in plan view. , And their intersections and ends communicate with the lower ends of the supply channels 11.

The lower end of the supply channel 11 is
A supply flow path 11a communicating with an end of the runner section 12 in one direction (one), a supply flow path 11b communicating with an end of the runner sections 12 in two directions (two), Supply flow path 11c communicating with the intersection of the runners 12, 12 in two directions (two)
And three types.

Accordingly, the sectional area of the supply flow path 11b is
The cross-sectional area is set to twice the cross-sectional area of the supply flow path 11c.
Is set to be four times the cross-sectional area of the supply channel 11a, and the unvulcanized rubber material 6 is placed in each of the cavities 8.
They are quickly and evenly filled.

FIG. 3 is a cross-sectional view of a main part of the transfer molding die 1 in a clamped state, and FIG. 4 is a cross-sectional view of a main part of the transfer molding die 1 in a released state. The upper mold 3
It has a rectangular plate-shaped main body 15 and a plurality of recesses 17... Provided on the lower surface of the main body 15 in an orderly manner.
A hemispherical concave portion 8a for forming the upper half of the cavity 8 is formed in the back portion of the cavity. The lower mold 4 is
A rectangular plate-shaped main body 16 and a plurality of convex portions provided on the upper surface of the main body 16 and at positions corresponding to the concave portions 17 of the upper die 3.
, And a hemispherical concave portion 8b for forming the lower half of the cavity 8 is formed on the upper surface of each convex portion 18.

A slight step 19 is provided between the concave portion 17 of the upper die 3 and the hemispherical concave portion 8a provided in the deep portion of the concave portion 17. The upper end surface of the convex portion 18 of the lower mold 4 comes into contact with 19. The gate portion 20 of the cavity 8 includes a semicircular narrow groove formed on the step 19 and a semicircular narrow groove formed on the upper end surface of the convex portion 18 of the lower mold 4. A runner section communicating with the gate section 20
Part of the end of 12 is open to the side of the concave portion 17, but is closed by the convex portion 18 of the lower die 4 when closing the mold, so that the gate portion 20 is closed.
Only the cavity 8 is opened.

An ejector is provided on the lower mold 4 side, and advancing / retracting sections 21 of the ejector are arranged at positions corresponding to the respective convex portions 18 of the lower mold 4. That is, a through hole is formed from the convex portion 18 to the main body portion 16 to allow the advance / retreat portion 21 to be inserted so as to be able to advance / retreat in the vertical direction. In the retracted state of the advance / retreat portion 21, the upper end surface 22 of the advance / retreat portion 21 and the upper end surface 23 of the surrounding convex portion 18 are formed in a mutually continuous concave curved shape.

The upper mold 3 and the lower mold 4 are provided with a plurality of hold pins 24 projecting into the cavity 8 so as to be able to advance and retreat. That is, in the main body 15 of the upper mold 3 and at positions corresponding to the respective hemispherical recesses 8a, vertical holes for inserting and holding the hold pins 24 on the upper mold 3 side so as to be able to advance and retreat are formed. In each of the advancing / retracting portions 21 of the ejector, there are formed vertical holes for inserting and holding the hold pins 24. Also, the upper die 3 and the lower die 4
The side hold pins 24 are provided at equal center angles and vertically opposed positions in a plan view, for example, three to four. The hold pins 24 on the upper die 3 side and the hold pins 24 on the lower die 4 side are driven up and down by an advance / retreat drive mechanism (not shown).

By the way, the tip surface of each of the hold pins 24 is formed in a concave curved surface, and when the hold pins 24 are retracted, the inner surface of the cavity 8, ie, the hemispherical concave portion 8 is formed.
The inner surfaces の of the a and 8b and the tip surfaces of the hold pins 24... are continuous (see FIG. 6).

When the hold pins 24 project, the hold pins on the upper die 3 project into the cavity 8.
A projecting dimension T ₁ of the 24, the lower die 4 projecting into the cavity 8
The difference between the projecting dimension T ₂ of the side of the hold pin 24, 0.03 mm to
It is set to 0.2mm. Specifically, for example, the upper mold 3
With projecting dimension T ₁ of the side of the hold pin 24 is set to 1.8 mm, the projecting dimension T ₂ of the lower die 4 side of the hold pin 24
It is set to 1.7 mm, and the upper die 3 has a slightly longer protruding dimension than the lower die 4.

Next, FIG. 5 shows a cross-sectional view of a main part in a state in which the inner core 9 is held in the cavity 8, and FIG. 6 shows a cross-sectional view of a main part in a transfer molding state. I will elaborate. Note that the present invention is a method for producing a multi-piece golf ball, and here, a multi-piece golf ball is defined as one having two or more pieces.

First, a golf ball core material (two-layer core)
First, as shown in FIG. 5, a vulcanized inner core 9 is placed in a transfer molding die 1.
To the inner surface of the cavity 8, ie, the hemispherical concave portions 8a, 8
and a spherical shell-shaped space 10 is held between the inner surface of b. That is, the hold pins 24 on the upper mold 3 side and the hold pins 24 on the lower mold 4 side are projected into the cavity 8 with predetermined projecting dimensions T ₁ and T ₂ , respectively. At 24, the inner core 9 is held and fixed. At this time, it is desirable that the surface of the inner core 9 is polished (buff polished) in advance.

Thereafter, as shown in FIGS. 1 and 6, an unvulcanized rubber material 6 is transfer-molded into a spherical shell-shaped space 10 in a cavity 8. That is, the unvulcanized rubber material 6 held (accommodated) in the pot portion 5 at the upper part of the upper die 3 is pressed by the compression extrusion portion 2 to supply the supply channels 11 and the respective runner portions 12.
Are filled in the voids 10 of each cavity 8. Then, an unvulcanized rubber layer 13 is laminated on the inner core 9 to form a spherical intermediate product.
14 is formed. At this time, since the pressed unvulcanized rubber material 6 is not vulcanized, the supply passages 11 and the runner portions 12
… And so on. In addition, spherical shell-shaped space
When the rubber material 6 is almost completely filled in the holder 10, the hold pins 24 are retracted.

The reason for buffing the surface of the inner core 9 is that the adhesion of the unvulcanized rubber layer 13 laminated on the inner core 9 becomes good, and the buffing is performed in comparison with the case where no buffing is performed.
This is because the deformation and eccentricity of the intermediate product (due to the shrinking force of the unvulcanized rubber layer) are greatly reduced.

Thereafter, as shown in FIG. 4, when the transfer molding die 1 is opened, the intermediate products 14 are separated from the hemispherical concave portions 8a of the upper die 3 and separated from the hemispherical concave portions 8b of the lower die 4. Remains on the side. More specifically, since the unvulcanized rubber layer 13 filled in the spherical shell-shaped space 10 is under pressure, the mold 1 is about to expand immediately upon opening, and this force (repulsive force) Is larger as the rubber volume is larger. By the way, as described in FIGS. 3 and 5, the hold pin 24 on the upper die 3 side is used.
Because ... is set a predetermined dimension (0.03mm~0.2mm) longer the protrusion dimension T ₁ from the lower mold 4 side of the hold pin 24 ... projecting dimension T ₂ of the of the upper die 3 side unvulcanized rubber layer 13 Volume (thickness)
Is larger than the lower mold 4 side. Accordingly, the unvulcanized rubber layer 13 having a larger volume on the upper mold 3 side has a larger repulsive force than the unvulcanized rubber layer 13 on the lower mold 4 side. The unvulcanized rubber layer 13 on the third side separates, and the intermediate product 14 remains on the lower mold 4 side.

The hold pins on the upper mold 3 and lower mold 4 sides
Is less than the difference between the protrusion dimension T _1, T ₂ of 24, 24 0.03 mm, there is a case where the intermediate article 14 when opening the mold 1 is attached to the upper die 3 side, it takes time to retrieve. Also, the protrusion dimensions T ₁ , T ₂
If the difference exceeds 0.2 mm, the thickness of the unvulcanized rubber layer 13 on the upper mold 3 side and the lower mold 4 side becomes too large, causing the eccentricity of the inner core 9.

Next, after the mold 1 is opened, the ejectors are driven to move the respective retracting portions 21 provided on the respective convex portions 18 of the lower mold 4.
… Is raised to push up each of the spherical intermediate products 14, and the intermediate products 14 are removed from the mold 1. And these intermediates 14 ...
Is put into a vulcanizing mold (not shown), and the unvulcanized rubber layers 13.
The core material is formed by vulcanizing (see FIG. 6). That is, a core material of a two-layer core in which a vulcanized rubber layer is laminated on the vulcanized inner core 9 is formed.

Since the unvulcanized rubber material 6 remaining in the runner portions 12 and the supply flow channels 11 does not solidify, it can be used for transfer molding to be performed sequentially. In addition, the thickness (inner diameter) and number of the runner portion 12 and the gate portion 20 can be freely changed to an appropriate design so that the unvulcanized rubber layer 13 is more strongly fitted to the inner core 9.
The cross-sectional areas (sizes) and ratios of the supply channels 11a, 11b, and 11c described with reference to FIG. 2 may be better changed depending on the material and the like.

In the case of manufacturing a core material of a three-layer core,
An unvulcanized rubber layer is transfer-molded again on a vulcanized inner core laminated with a vulcanized rubber layer (two-layer core),
Thereafter, vulcanization molding may be performed.

According to the present invention, a two-piece golf ball can also be manufactured. That is, an unvulcanized rubber layer is laminated on the vulcanized inner core by transfer molding to form a spherical intermediate product, and then the intermediate product is vulcanized into a vulcanizing mold having a dimple-forming protrusion on the inner surface of the cavity. And put
Dimples are formed while vulcanizing the unvulcanized rubber layer.

In the transfer molding die 1 described with reference to FIGS. 1 to 6, the advancing / retracting portions 21 of the ejector are omitted, and intermediate products are provided by hold pins 24 provided to the lower die 4 so as to be able to reciprocate. 14 may be pushed up so that it can be taken out. That is, the hold pins 24 are configured to be able to protrude in two steps so that they can protrude to a height dimension (height at which the intermediate product 14 can be easily taken out) larger than the protruding dimension for holding the inner core 9.

FIG. 7 shows another transfer molding die 1. This transfer die 1 has a fixed upper die 3 and a lower die 4 with the hold pins 24 projecting into the cavity 8. As shown in FIG.
It is provided in. In this case, in the unvulcanized rubber layer of the intermediate product taken out from the mold 1 after the transfer molding, the holes due to the hold pins 24 are clear, but the holes are shallow (short) due to shrinkage immediately because they are unvulcanized. The holes are completely closed by the flow of rubber during vulcanization molding. At this time, the amount of the unvulcanized rubber material to be filled at the time of transfer molding is set so that the holes are closed.

The present invention is not limited to the above-described embodiment. For example, the hold pin 24 on the lower mold 4 may be protruded by a predetermined length longer than the hold pin 24 on the upper mold 3 to form the mold 1.
At the time of release, an intermediate product may be attached to the upper mold 3 side.
In this case, the intermediate product is taken out, for example, by dropping the intermediate product by projecting the retreating hold pin 24 on the upper die 3 side again and moving the intermediate plate between the upper die 3 and the lower die 4. And collect it.

In this embodiment, the case where the runner section 12 and the supply flow path 11 are provided on the upper mold 3 side has been described, but the runner section 12 and the supply flow path 11. (In this case, a mold obtained by turning the mold 1 shown in FIGS. 1 and 7 upside down is used.) That is, the inside of one of the upper mold 3 and the lower mold 4 is used. , The runner sections 12 and the supply flow paths 11 may be provided.

Next, under the following conditions, an intermediate golf ball core material was manufactured by the golf ball manufacturing method of the present invention as an example, and FIGS. 8 and 9 show comparative examples.
By using the conventional manufacturing method described in the above section, a golf ball core material intermediate product was produced.

(Preparation Conditions of Examples) The composition of the inner core and the composition of the rubber material for the outer layer were as follows. BR01: 100 parts by weight (cis 97% polybutadiene manufactured by Nippon Synthetic Rubber Co., Ltd.) Zinc acrylate: 25 parts by weight Zinc flower: 20 parts by weight Dicumyl peroxide: 1 part by weight A vulcanized press manufactured at 34 ° C. for 20 minutes was used. The rubber material for the outer layer was prepared by kneading the above composition. The transfer molding die described with reference to FIG. 7 was used. The inner diameter of the cavity was 37 mm. The rubber material for the outer layer is injected into the pot portion of the transfer molding die using an injection molding machine and weighed, and then the weighed rubber material is compressed at the compression extrusion portion (mold clamping speed 20 mm / s).
Injected into the cavity. After clamping, the mold was held for 1 second, the mold was opened, a spherical intermediate product (preliminary molded product) was taken out, and then put into a vulcanization mold, and the outer layer was vulcanized.

(Preparation Conditions for Comparative Example) The preforming mold described with reference to FIGS. 8 and 9 was used. 3.4 g is added to each concave portion c, c of the pair of half bodies a, a of the lower mold b.
Was pressed for 10 seconds with the upper mold f to form unvulcanized rubber layers g, g in a hemispherical shell shape. After that, the vulcanized inner core h is put on one unvulcanized rubber layer g, the other half a is folded and pressed for 10 seconds, and a spherical intermediate product (preformed product) is taken out. It was put into a molding die and the outer layer was vulcanized.

As a result, the time required for forming the outer layer was 11 seconds in the example and 20 seconds in the comparative example. Further, there was no peeling of the vulcanized rubber layer of the example, and about 30% of the vulcanized rubber layer of the comparative example was peeled off. The eccentricity of the inner core was 0.1 mm in the example and 0.3 mm in the comparative example. In the case of the comparative example, if the pressing time was shorter than 10 seconds, the peeling became more severe, and the peeling could not be prevented even if the pressing pressure was increased.

As described above, the embodiment has less eccentricity, does not peel off, and is more efficient than the comparative example. That is, the core material and golf ball formed by vulcanization molding,
It can be efficiently manufactured with high quality.

[0043]

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

According to claim 1, an unvulcanized rubber layer laminated outside the inner core 9 by transfer molding
Since a strong force can be applied to the unvulcanized rubber layer 13
No peeling occurs, the rubber material 6 is not wasted, and an extremely thin layer can be manufactured. Further, a spherical shell-shaped space 10 is formed in the cavity 8.
Since the inner core 9 is held and filled with the unvulcanized rubber material 6, the eccentricity of the inner core 9 of the transfer molded intermediate product 14 is reduced. Therefore, a high-quality golf ball with high dimensional accuracy can be manufactured.

According to the second aspect, at the time of transfer molding, the inner core 9 can be securely held in the cavity 8 (substantially at the center position) with the spherical shell-shaped space 10. The eccentricity of the inner core 9 can be reliably reduced.

According to the third aspect, when the mold 1 is released after the transfer molding, the spherical intermediate product 14 can be left on the lower mold 4 side or the upper mold 3 side. Therefore, when transfer molding a large number of intermediate products 14 at one time, the mold 1
When the intermediate products 14 are released, the intermediate products 14 can be aligned with the lower mold 4 or the upper mold 3, so that the intermediate product removal process can be performed smoothly and efficiently, and the productivity is greatly improved.

According to the fourth aspect, the adhesion of the transfer-molded unvulcanized rubber layer 13 to the inner core 9 is improved, and the deformation and eccentricity of the spherical intermediate product 14 are further reduced (compared to the case without polishing). I do.

When the mold 1 is released after the transfer molding, the unvulcanized rubber material 6 does not protrude from the runner portion 12. Accordingly, the protruding rubber material 6 does not hinder the mold clamping, and
Since there is no need to remove the rubber material, productivity is improved.

[Brief description of the drawings]

FIG. 1 is a simplified explanatory view showing one embodiment of a method for manufacturing a golf ball of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between a supply channel and a runner portion with respect to a cavity.

FIG. 3 is a cross-sectional view illustrating a main part of the transfer molding die in a clamped state.

FIG. 4 is a sectional view of a main part showing a released state of a transfer molding die.

FIG. 5 is a fragmentary cross-sectional view showing a state where an inner core is held in a cavity.

FIG. 6 is a sectional view of a main part showing a transfer molding state.

FIG. 7 is a cross-sectional view showing another transfer molding die.

FIG. 8 is a first explanatory diagram showing a conventional example.

FIG. 9 is a second explanatory diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Transfer molding die 3 Upper die 4 Lower die 5 Pot part 6 Rubber material 8 Cavity 9 Inner core 10 Spherical shell-shaped space 12 Runner part 13 Unvulcanized rubber layer 14 Spherical intermediate product 20 Gate part 24 Hold pin T ₁ Projection dimensions T ₂ projecting dimension

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B29K 105: 24 B29L 31:54 F term (Reference) 4F202 AA45 AD05 AD27 AG03 AH61 CA12 CB01 CB12 CK02 CK89 CQ03 CQ07 4F206 AA45 AD05 AD27 AG03 AH61 JA02 JB12 JF05 JQ81

Claims (5)

[Claims] 1. A transfer molding die 1 having a pot portion 5 for holding a predetermined amount of an unvulcanized rubber material 6 and having an upper die 3 and a lower die 4 is provided with a vulcanized inner core 9. Is held between the inner surface of the cavity 8 and the spherical shell-shaped void 10, the unvulcanized rubber material 6 in the pot portion 5 is filled in the spherical shell-shaped void 10, and the unvulcanized rubber is added to the inner core 9. The spherical intermediate product 14 is transfer-molded by laminating the layers 13 and then the spherical intermediate product 14 is taken out of the transfer molding die 1 and put into a vulcanization molding die, and the unvulcanized rubber layer is formed. 13. A method for producing a golf ball, comprising vulcanizing 13 to form a core material or a golf ball. 2. A plurality of hold pins 24 projecting into the cavity 8 of the transfer molding die 1 are provided in the upper mold 3 and the lower mold 4 so as to be able to advance and retreat or in a fixed manner. 24. The method of manufacturing a golf ball according to claim 1, wherein the inner core 9 is held with a spherical shell-shaped gap 10 between the inner core 9 and the inner surface of the cavity 8. 3. The difference between the protrusion dimension T ₁ of the hold pin 24 on the upper mold 3 side protruding into the cavity 8 and the protrusion dimension T ₂ of the hold pin 24 on the lower mold 4 side protruding into the cavity 8. 3. The method for producing a golf ball according to claim 1, wherein the distance is set to 0.03 mm to 0.2 mm. 4. The golf ball manufacturing method according to claim 1, wherein the surface of the inner core 9 held in the transfer molding die 1 is polished in advance. 5. A runner portion 12 communicating with a gate portion 20 of a cavity 8 of a transfer molding die 1 is disposed inside one of an upper die 3 and a lower die 4.
Or the method of manufacturing a golf ball according to 4.