JP4025938B2 - Golf ball manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a golf ball manufacturing method capable of injection-molding a uniform thin layer on the surface of a solid core of a solid golf ball or a wound core of a wound golf ball.
[0002]
[Prior art]
Golf balls have a solid type with a rubber elastic elastic body covered with a resin cover around a spherical solid core, and a balata or resin on the surface of a wound core with a thread rubber layer on the solid center. Although it is roughly classified into a thread-wound type formed by covering with a cover such as a cover, when a cover is formed on a core (core ball) using a resin such as a thermoplastic resin, the cover is applied to any type of core. It is common to perform injection molding of the material.
[0003]
For example, FIG. 6 is a cross-sectional view of a mold 1 showing conventionally known injection molding, and this mold 1 has a split mold composed of an upper mold 2 and a lower mold 3, A spherical cavity 4 is formed inside by joining the respective split surfaces (parting lines) P of the upper and lower molds 2 and 3, and the equator plane of the cavity 4 coincides with the position of the split surface P It is.
[0004]
Here, the upper mold 2 and the lower mold 3 are each provided with a plurality of support pins 5 so that the tips are located in the very vicinity of the spherical cavity 4, and a core ball (core in the illustrated example) disposed at the center of the cavity. 6 is provided so as to be sandwiched by the tips of these support pins 5 from above and below.
[0005]
6 includes a runner 7 for supplying an injection material by joining the upper and lower split molds 2 and 3 and a gate 8 for introducing a molding resin supplied from the runner 7 into the cavity 4. To do. In addition, gas venting means 9 including a pin a having a convex cross section and a gas vent hole b through which the pin a passes are provided at the pole (pole) position of the cavity 4. It is provided so that the gas in the cavity 4 is discharged from the gap formed between them.
[0006]
In order to injection-mold thermoplastic resin as a cover material on the core 6 using the mold shown in FIG. 6, the core 6 is inserted into the cavity 4, and the core 6 is supported from above and below by the support pins 5. Then, a thermoplastic resin is supplied from a supply source (not shown) to the runner 7 and the gate 8, and the resin 12 is injected (press-fitted) into the space 11 between the surface of the core 6 and the inner wall surface 10 of the mold. It is done by doing.
[0007]
In this case, the support pins 5 that support the core 6 are gradually retracted according to the material introduction state, and the level of the mold wall surface 10 (the tip of the pin is the shape of the desired molding surface) at the end of material injection or just before the end. The injection molding is terminated by ending the resin supply.
[0008]
Although not shown, a large number of projections for molding dimples are arranged on the mold inner wall surface 10 constituting the cavity 4, and a large number of dimples are formed on the surface of the golf ball when the injection molding is completed. It is configured to be.
[0009]
[Problems to be solved by the invention]
When the state before injection of the mold 1 in FIG. 6 is taken up only by taking only the center of the cavity, the core 6 is the tip of each support pin 5 provided in the upper and lower molds 2 and 3 as shown in FIG. Thus, both poles are supported near the center of the cavity. In this case, the tip of the support pin 5 is usually press-fit enough to support the core, and the core 6 is hardly deformed.
[0010]
By the way, in recent years, with the softening of golf balls, the core hardness of solid cores in particular tends to be soft, and a thin cover tends to be required. On the other hand, the gate of the mold is provided by joining the split mold as in the above type, or even if it is a tunnel gate formed only in one split mold, the purpose of gate cutting Therefore, an injection port is often provided at a position very close to the split surface, and a resin having an internal pressure of 400 to 2000 kg / cm ² or more is supplied to the core during injection molding.
[0011]
For this reason, when the core is hard and the cover is thick, if the cover material resin is well balanced, the core will not be decentered. However, if the core is soft, injection is performed as shown in FIG. The core surface close to the gate may be partially deformed by the pressure, which may cause a problem that eccentricity or unevenness of the formed cover thickness occurs.
[0012]
The reason for this is that if the core is soft, deformation and blurring during injection increase, and the resin is slightly out of balance between the gates, making it easy to be eccentric.
[0013]
Further, when the cover is to be formed thin with the above-described mold, the gap at the deepest portion (near the pole) of the cavity becomes small due to the deformation of the core as described above, and the cover thickness of this portion becomes thin. There is also a problem that filling failure tends to occur when forming a cover of 3 mm or less, particularly 1.0 mm or less.
[0014]
The present invention has been made in view of the above problems. Even when a relatively soft core is used or when a thin molding layer of 1.3 mm or less, particularly 1.0 mm or less is formed, a conventional injection molding metal is used. An object of the present invention is to provide a golf ball manufacturing method capable of forming a molding layer having a uniform thickness while avoiding eccentricity of a core using a mold.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides the following golf ball manufacturing method.
Claim 1: A spherical cavity is formed on the inner wall surface, and there are a plurality of split molds having split faces at positions substantially coincident with the equator plane of the spherical cavity, and a plurality of molds are perpendicular to the equator plane. Using molds each provided with a support pin capable of advancing and retreating, a core ball is placed in the spherical cavity, the core ball is supported by the support pin at the center of the cavity, and between the surface of the core ball and the inner wall surface of the mold. In the golf ball manufacturing method for forming a molding layer on the surface of the core ball by introducing the molding material into the void,
When supporting the core ball in the center of the cavity, if the deflection when the core ball is pressed with 100 kg is A (mm) and the thickness of the molding layer to be formed is B (mm), the holding margin of each support pin ( A method of manufacturing a golf ball, comprising adjusting a deformation amount Y (mm) of a core ball by each support pin so as to satisfy the following range (1).
A / 4B− (0.1 + A / 10B) ≦ Y ≦ A / 4B + (0.1 + A / 8B)
Claim 2: The mold is composed of two split molds, each of which has at least three support pins, and these support pins are arranged at equal intervals at the pole center of the cavity. The method for manufacturing a golf ball according to claim 1.
(3) If the region that completely surrounds all the support pins in which the mold is arranged in the same split mold in the vertical direction is a virtual region, the support pins are arranged so that the minimum virtual region is 60 to 450 mm ^2. The method for producing a golf ball according to claim 1, wherein the golf ball is produced.
Claim 4: The support pins are arranged such that the sum of the cross-sectional areas of all the support pins in which the molds are arranged in the same split mold is 20 to 100 mm ^2. A method for producing the golf ball according to claim.
[0016]
That is, the present inventor forms a spherical cavity on the inner wall surface, has a plurality of split molds having split faces at positions substantially coincident with the equator plane of the spherical cavity, and is perpendicular to the equator plane. Using a mold provided with a plurality of support pins that can be advanced and retracted, a core ball is placed in the spherical cavity, the core ball is supported by the support pin at the center of the cavity, the surface of the core ball, the inner wall surface of the mold, When forming a molding layer on the surface of the core sphere by introducing a molding material into the space between, depending on the hardness of the core sphere on which the molding layer is formed and the desired thickness of the layer to be molded, By optimizing the gripping allowance of the support pins that support the core ball, it is possible to injection-mold a thin cover with a uniform thickness without any eccentricity, especially for softened core balls. Yes, and also applicable when forming a thin layer such as an intermediate layer other than the cover Getting, solid core of a single-layer or multi-layer structure of the solid golf ball, found that can satisfactorily injection molded to wound core or cover of a multilayer structure, the thread-wound golf balls, in which the present invention has been accomplished.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0018]
As described above, the golf ball manufacturing method of the present invention performs injection molding using a conventionally known injection molding die.
[0019]
That is, the injection mold used in the present invention forms a spherical cavity 4 on the inner wall surface, like the injection mold 1 shown in FIG. 6 described above, and substantially coincides with the equator plane of the spherical cavity 4. A plurality of split molds 2 and 3 having a split surface at a position (two split types in the example of FIG. 6) and a plurality of support pins provided through the split mold in a direction perpendicular to the equator plane. Things can be illustrated.
[0020]
In the following description, with respect to the configuration of the mold 1, the same components as those shown in FIG.
[0021]
In the manufacturing method of the present invention, a core sphere 6 (solid core in the illustrated example) is placed in the spherical cavity 4 of the mold 1, and the core sphere 6 is supported at the center of the cavity by a support pin 5. The molding material is introduced into the space 11 between the mold and the inner wall surface 10 of the mold, but since the injection molding layer can be thinned as described later, the outer layer cover, the inner layer cover, and the intermediate layer are formed. Therefore, the present invention is applied to a single-layer or multi-layer core of a solid golf ball, a thread-wound core formed by winding a thread-wound rubber around a solid center or a liquid center of a thread-wound golf ball. Further, as the molding material, a cover material or an intermediate layer material that is currently used for golf balls, such as a thermoplastic resin such as an ionomer resin, polyether ester, polyurethane, or polyamide, can be used.
[0022]
The golf ball manufacturing method of the present invention requires that the core sphere 6 in contact with the support pin 5 be supported in a partially deformed state.
[0023]
That is, FIG. 1 is a partially enlarged cross-sectional view showing a core ball arranged in the mold 1, and uses an injection mold that supports the core ball with a support pin 5. When the sphere 6 is supported, a part of the core sphere is supported by the support pin 5 instead of simply supporting the core sphere 6 at the center of the cavity without being bent as in the conventional example (for example, the holding method of FIG. 7). Is deformed, and the deformation amount of the core ball (hereinafter referred to as a gripping margin) is optimized and supported.
[0024]
Here, the gripping allowance Y (mm) of the present invention is the following range A when the deflection amount A (mm) when the core ball is loaded with 100 kg and the thickness of the formed layer is B (mm). /4B-(0.1+A/10B)≦Y≦A/4B+(0.1+A/8B)
It is necessary to adjust to the hardness of the core sphere and the thickness of the molding layer. If the gripping allowance is smaller than the above value, the core is easily decentered due to the deformation of the core due to the injection pressure and the gate balance, and if it is a large value, the pin will touch the core and cause a chipping of the core, The core is deformed too much and the space 11 near the gate 8 becomes narrow, making it difficult for the molding material to enter, and the mold internal pressure (injection pressure) becomes excessively high.
[0025]
The amount of deflection of the core ball refers to the amount of deformation that occurs when the core ball is placed on a flat surface and a load of 100 kg is applied via a flat plate.
[0026]
The manufacturing method of the present invention is to support the core ball by adjusting the gripping amount. In this case, as shown in FIG. 2, the support pin 5 is in contact with the surface of the core ball 6 without being bent. , And the core ball 6 is deformed by pressing with the support pin 5 so as to be a value specified within the above range with reference to this position. As shown in FIG. The distance between the deformed core spheres (solid lines) is set to the specified gripping allowance.
[0027]
Here, the gripping margin is set for each support pin, but is determined by the hardness of the core ball and the thickness of the molding layer, so the length of the support pins arranged in the same split mold Even if the cross-sectional areas have different widths or the like, they are set to have the same gripping allowance.
[0028]
The mold used in the present invention may be any mold having a plurality of conventionally known split molds. However, in order to improve the injection conditions, the mold is divided into two split molds having the same shape. The type is preferred.
[0029]
In addition, the support pins included in each split mold can be appropriately selected according to the support state of the core ball, but 3 or more, particularly 3 to 5 are arranged in each split mold, In this case, the tip of the pin should be arranged at equal intervals around the pole of the cavity, which is provided perpendicular to the equatorial plane (split mold joint surface) of the spherical cavity to be formed. Is preferred.
[0030]
In the present invention, further, if the area that completely surround the entire support pins arranged in the same mold part in a vertical direction and a virtual area, the minimum virtual area 60～450Mm ^2, so that particularly in 80～300Mm ² If it is less than 60 mm ² , the core may not be held at the center. On the other hand, if it exceeds 450 mm ² , an error in the gripping margin with respect to the outer diameter of the core becomes large, and it becomes easy to be eccentric. In addition, when used as a pin for forming dimples at the tip, the dimples are not preferable.
[0031]
Here, a specific example of the minimum virtual region will be described with reference to FIG. 4. FIG. 4 is a front view of one split mold viewed from the inner wall side, and the tips of the three support pins 5 are the cavities 4. They are arranged at equal intervals so as to be located on a concentric circle with the pole p as the center.
[0032]
In the present invention, the minimum virtual region means a virtual plane T (when there are three support pins 5) formed by connecting three support pins on the same plane from the outside (so as to contact each other) with straight lines. Is a shape close to an equilateral triangle), and when there are four support pins, the virtual plane connected by straight lines circumscribing each pin has a shape similar to a square, and similarly 5 In the case of having more than one support pin, the minimum virtual region is a planar region similar to a regular polygon of a regular pentagon or more.
[0033]
In this invention, it is preferable to adjust so that the sum total of the cross-sectional area of the support pin arrange | positioned in the same split mold may be 20-100 mm < ² >, especially 20-75 mm < ² >. If the total cross-sectional area is less than 20 mm ² , the pin will touch the core and the core will be easily chipped. On the other hand, if it is greater than 100 mm ² , the flow of the molding material will be poor with respect to the support position by the pin and May decrease.
[0034]
The production method of the present invention is not particularly limited as long as the above requirements are satisfied, and injection molding can be performed according to a known method. Therefore, in the injection molding, an appropriate molding material may be supplied in the order of the runner 7 and the gate 8 and introduced into the cavity.
[0035]
In this case, since the molding material injected from the gate 8 hits the nearest core ball 6 while maintaining a high injection pressure, the gripping allowance of the pin 5 supporting the core ball is restored with the momentum, and the support pin is moved. When pushed out to the outside, the core sphere returns to the original spherical shape, and when the filling of the void is completed, the shape of the core sphere is completely restored (FIG. 5).
[0036]
Therefore, according to the manufacturing method of the present invention, there is no eccentricity of the core ball due to the injection pressure, and a molding layer having a uniform thickness can be formed. Even when the thickness is 0 mm or less, injection molding can be easily performed by simply adjusting the gripping margin.
[0037]
The mold used in the present invention can be appropriately selected depending on the type of the molding layer formed on the core ball. For example, when the molding layer is a cover, the illustration is omitted, but the inner wall surface of the mold is omitted. Can be used in which a large number of projections for shaping the dimples are arranged.
[0038]
In addition, when producing a multilayer structure core by injection molding, for example, when producing a solid structure having a multilayer structure composed of a plurality of layers having different physical properties, when covering the inner layer of the cover on the core, For further coating on the inner layer coated with the outer layer, a mold having a flat inner wall surface can be selectively used.
[0039]
Furthermore, the gate type of the mold is not limited to the type formed when the above-described split molds are joined, and may be a tunnel gate formed inside one split mold.
[0040]
The embodiment of the present invention will be described. In this embodiment, the core ball 6 (elastic spherical core in this embodiment) is supported by a support pin as shown in FIG. By joining the split molds 2 and 3, a spherical cavity 4 is formed inside, and a split surface P is provided at a position coinciding with the equator plane of the cavity 4. Injection molding is performed using a mold 1 provided with three support pins 5 so as to be able to advance and retreat in a direction perpendicular to the surface.
[0041]
The mold 1 supports a spherical elastic core 6 as a core sphere at the center of the cavity 4 by respective support pins 5, and splits against a cavity 11 formed between the core 6 and the mold wall surface. The molding is performed by injecting a molding material (in this example, a cover material such as an ionomer resin) through the runner 7 and the gate 8 formed on the surface P. Although not shown, the position of the gate 8 is illustrated. These are provided at six locations spaced apart at equal intervals around the split surface P of the upper and lower molds 2 and 3.
[0042]
Here, in this embodiment, when the core 6 is supported by the support pin 5, the core 4 is urged until it is pushed by the pin and partially deformed as shown in FIG. As a result, the core 4 is pressed in the axial direction of the support pin 5, that is, the upper and lower directions and spreads and deforms in the equator direction, and the gap space of the space 11 formed on the wall surface between the core 4 and the mold 1 is In the vicinity of both poles where the support pins 5 are provided, the area expands and decreases in the vicinity of the equator near the gate 8 (FIG. 1).
[0043]
In this case, the holding margin Y of the support pin 5 is obtained by deforming the solid core 6 as shown in FIG. 3 from the position where the support pin 5 contacts without deforming the core 6 as shown in FIG. It is something to support. That is, FIG. 2 is a partially enlarged view showing a state in which the tip of the support pin 5 is in contact with the solid core 6. Most of the injection-molded core 6 of the conventional example is supported at this position and injection is performed. On the other hand, in the present invention, the core support state by the support pins 5 is not limited to the position shown in FIG. 2, but is supported by pressing further from the state shown in FIG. Is. That is, as shown in FIG. 3, due to the axial pressing of each support pin 5, the original surface shape of the core 6 indicated by a broken line becomes a concave portion with a deformation amount Y (mm) at a position indicated by a solid line. Deformed and supported.
[0044]
Here, the deformation amount Y (mm) of the core, that is, the gripping margin Y (mm) of the support pin, the deflection amount A (mm) when the core is loaded with 100 kg load, and the thickness of the cover to be formed B ( mm), as described above, it is adjusted to a value shown in the following range.
A / 4B− (0.1 + A / 10B) ≦ Y ≦ A / 4B + (0.1 + A / 8B)
[0045]
In this example, the amount of bending of the core when a 100 kg load is applied is 4.0 mm, the desired thickness of the cover layer to be molded is 1.3 mm, and the gripping margin is 0.77 mm.
[0046]
FIG. 4 is an enlarged plan view showing an arrangement portion of the support pins 5 when the upper mold 2 or the lower mold 3 is viewed from the inner surface of the mold in the examples of FIGS.
[0047]
In FIG. 4, the support pins 5 are arranged such that the tips of the three support pins 5 are arranged at equal intervals on a concentric circle with the pole p as the center. In this case, the area of the imaginary plane (nearly equilateral triangle) and the equator plane of the cavity (division surface of the mold) formed when the support pins are connected in a straight line so as to circumscribe each pin is The range is 139.3 mm ² . Furthermore, in FIG. 4, the sum total of the cross-sectional areas shown by diagonal lines of the support pins is 30.5 mm ² .
[0048]
【The invention's effect】
The golf ball manufacturing method of the present invention is capable of avoiding eccentricity and injection-molding a uniform thin layer on the surface of a solid core or the like of a solid golf ball.
[Brief description of the drawings]
FIG. 1 is a partially enlarged view showing an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a base point of a gripping allowance in the same example.
FIG. 3 is an explanatory diagram showing a gripping allowance in the same example.
FIG. 4 is an explanatory diagram showing a virtual plane of the present invention.
FIG. 5 is a partially enlarged view showing the inside of a mold after injection molding according to the present invention.
FIG. 6 is a schematic view showing an injection mold.
FIG. 7 is a partially enlarged view showing a conventional supporting method.
FIG. 8 is a partially enlarged view showing a state where a core of a conventional example is deformed.
[Explanation of symbols]
1 Mold 2 Upper mold 3 Lower mold 4 Cavity 5 Support pin 6 Core ball

Claims (4)

A spherical cavity is formed on the inner wall surface, and there are a plurality of split molds having a split surface at a position substantially coincident with the equator plane of the spherical cavity, and a plurality of support pins are provided in a direction perpendicular to the equator plane. Using a mold prepared for advancement and retraction, a core ball is placed in the spherical cavity, the core ball is supported at the center of the cavity by a support pin, and molded in a space between the core ball surface and the inner wall surface of the mold. In the golf ball manufacturing method of forming a molding layer on the surface of the core ball by introducing the material,
When supporting the core ball in the center of the cavity, if the deflection when the core ball is pressed with 100 kg is A (mm) and the thickness of the molding layer to be formed is B (mm), the holding margin of each support pin ( A method for producing a golf ball, characterized in that the deformation amount (Y) of the core ball by each support pin (Y) is adjusted within the following range.
A / 4B− (0.1 + A / 10B) ≦ Y ≦ A / 4B + (0.1 + A / 8B) 2. The mold according to claim 1, wherein the mold includes two split molds, each of the split molds includes at least three support pins, and the support pins are arranged at equal intervals at the pole center of the cavity. Golf ball manufacturing method. When an area that completely surrounds all the support pins arranged in the same split mold in the vertical direction is a virtual area, the support pins are arranged so that the minimum virtual area is 60 to 450 mm ^2. A method for producing a golf ball according to claim 1. 4. The golf ball according to claim 1, wherein the support pins are arranged such that a total cross-sectional area of all the support pins in which the molds are arranged in the same split mold is 20 to 100 mm ^2. Manufacturing method.

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