JPH05208053A - Seamless golf ball and method and appa- ratus for manufacturing the same - Google Patents

Abstract

PURPOSE: To manufacture a golf ball which has a uniform characteristic and noncomformity. CONSTITUTION: An upper metal mold 30 and a lower metal mold 12 have a large number of pins 24, 26 respectively, and a core 28 that has been projectingly and previously manufactured is supported inside hemispherical cavity parts 34 and 36. The lower metal mold 12 on the one side is provided with ejection pins, so that the extrusion of the golf ball after cooling and the separation from the mold thereof can be enabled. Either or both of the upper metal mold 10 and/or the lower metal mold 12 are provided with pouring ports, and heated liquid polymer is supplied to the cavity parts 34, 36 of the respective molds. A plurality of projecting dimples are arranged to the surface of the cavity parts 34, 36 of both the upper metal mold 10 and the lower metal mold 12 of the same hemispherical dimension. Thus, recessed dimples are formed on the surface of a golf ball during the molding work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball having no seam on the surface of the outer cover and a method and apparatus for manufacturing the same.

[0002]

2. Description of the Related Art The manufacture of golf balls comprises several different stages depending on the type of ball, namely one-piece, two-piece and three-piece. Traditionally, the core is composed of a single elastomer or a composite elastomer, and the periphery of the core is covered with a dimpled skin. Injection molding is one of the methods for forming the outer cover of a golf ball. The core is placed in the center of the cavity of the two-part mold and fixed in the center using retractable pins. A constituent of the outer skin, for example, an ionomer, is heated to a liquid state and poured into the cavity of the mold from a sprue near the dividing line between the upper mold and the lower mold. When it is removed from the mold after cooling, many solidified runners and burrs made of excess skin material are attached and are scattered from the sprue to the seam of the mold's score lines. This burr or runner must be removed from the golf ball by a separate grinding operation. Grinding work lacks accuracy and often creates irregularities on the surface of the skin. After removing the burrs, the golf ball is coated with a known paint composition to give a gloss finish. Since burrs are formed along the line of the seam during the molding operation, it is not possible to cross the score lines to form dimples. As a result, the possible dimple patterns are limited. For example, US Pat.
The disclosure of 653,758 shows the use of two hemispherical shaped skins with wavy mating surfaces. Although this method shows an improvement in the dimple symmetry, burrs still remain on the golf ball, and it is not possible to provide dimples on the connecting surface of the two hemispherical-shaped outer skins. Another problem arises with the injection or molding of golf ball skins. This is particularly the case when a multicavity relative-type cavity is used in one machine. As is often the case, it is not possible to accurately align all of the upper and lower dies before or during the injection operation. As a result, a problem occurs. For example, imperfect joining of secant lines, non-round golf balls, outer skin that is not concentric with a spherical inner core, etc. All of the above problems have the drawback of resulting in golf balls with variations in performance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and a seamless golf ball and a method of manufacturing the same, which makes it possible to manufacture a golf ball having uniform characteristics and no defects. It is to provide a device.

[0004]

According to a first aspect of the present invention, a pair of an upper mold and a lower mold are fitted along a common center line that fits an upper mold and a lower mold and applies a high pressure to form a cavity. Combine the molds,
A method for manufacturing a golf ball in which a heated liquid polymer is injected into a cavity and then cooled to form no joint on the outer cover, which is used for connecting an upper mold and a lower mold. The slanted surface forces accurate fitting, and either the upper die or the lower die floats perpendicularly to the axis, which allows for centering around the axis. A fifth aspect of the present invention is an apparatus for seamlessly forming an outer cover on a golf ball, and by applying a high pressure to a pair of an upper mold and a lower mold, the device is joined around the central shaft and has a secant. The cavity of the mold is formed, and the plastic solution is injected into the mold to solidify, but the wedges are closed by tilting the opposing alignment surfaces between the mold cavities and closing the mold. In order to accurately align the upper and lower dies around the shaft and along the score line, one of the upper and lower dies performs limited movement in the direction perpendicular to the axis. The feature is that accurate alignment is possible. The invention of claim 10 is a golf ball having an outer skin formed between two upper and lower dies joined on a common dividing line, and some of a large number of dimples formed on the outer skin. The feature is that the dimples of cross the secant. The invention of claim 11 is a golf ball molded between a pair of upper mold and lower mold fitted around the score line, and after taking out from the mold, at a position corresponding to the score line. It features no seams and no burrs.

[0005]

According to the present invention, by providing mating inclined surfaces on both the upper mold and the lower mold which are opposed to each other, when the upper mold and the lower mold are joined while being pressed, the upper mold and the lower mold are bonded to each other. The mold and lower mold can be aligned accurately. Either the upper mold or the lower mold is capable of lateral movement to some extent,
It is easy to line up. This prevents the liquid polymer from leaking around the secant during injection, and enables a very small tolerance in the secant.
Therefore, no visible seams are molded during the molding operation. The liquid shell material is injected into one or two poles through one or more heated sprues. Since the molten molten shell material is continuously flown through the sprue, runners and burrs that need to be removed later are not formed. Since the outer cover is formed in a seamless manner, it is possible to form the dimples on the score line or in the vicinity thereof. Further, since the molding is performed on a horizontal surface, it is easy to take out the completed golf ball. The molding of the golf ball according to the present invention is performed with a high degree of reliability and precision, and as a result, it is possible to manufacture a golf ball having uniform characteristics and no defects.

[0006]

EXAMPLE As shown in FIG. 1, an upper die 10 and a lower die 1
2 is formed in a cylindrical shape with respect to the shaft 14. Upper mold 10
And the lower mold 12 is held by the mold mounting plate,
For simplification, in FIG. 1, the lower mold mounting plate 16 for the lower mold 12 is shown.
Show only. Each of the upper mold 10 and the lower mold 12 is provided with a pair of spaced outer cylindrical shoulders 18 and 20, which fit into corresponding circular holes on the mold mounting plate. It is supposed to do. Shoulder 1
8, the closed chamber 21 defined by the shoulder 20 and the mold mounting plate 16 is for circulating the cooling liquid after the injection molding process. The upper mold 10 and the lower mold 12 shown in the separated positions are provided with a shaft 14
The mold is closed by simultaneously moving along and applying high pressure around the circular secant defined by the circular edge 22.
The upper mold 10 and the lower mold 12 are provided with a large number of pins 24 and 26, and are protruded into the hemispherical cavity portion 34 and the cavity portion 36 to be manufactured in advance of a conventional one-piece or two-piece structure. Supports an elastomeric core 28.
One of the lower molds 12 is provided with an ejection pin 30, which allows the golf ball to be extruded and separated from the mold after cooling. One or both of the upper die 10 and the lower die 12 has an injection port, and the cavity portion 34 of the die,
Feed heated liquid polymer to 36. The heated gate 32 reaches the cavity 34 point of the upper mold 10 away from the secant, preferably one or more poles along the axis 14. Upper mold 10 and lower mold 12
A plurality of convex dimples are attached to the surfaces of the hemispherical cavity portions 34 and 36 of the same size (not shown),
This forms concave dimples on the surface of the golf ball during the molding operation.

Next, a method of manufacturing a golf ball will be described. The upper mold 10 and the lower mold 12 are separated to separate the cavity parts 34, 3
Elastomer core 28 is placed in 6 and pins 24, 2
Use 6 to support it in the middle. The core 28 may be a known type of homogeneous elastomer composition, or may be layered, that is, the inner core may be wrapped with a rubber band. Alternatively, the core 28 may be omitted and the one-piece ball may be molded by injection only. By closing the upper mold 10 and the lower mold 12, a spherical outer shell-like space is formed between the core 28 and the surfaces of the cavities 34, 36. The hot liquid polymer is then injected through the gate 32 into the space around the wick 28. The polymers used to construct the skin may be thermosetting and thermoforming components such as inomers and other natural or synthetic elastomers, or polymers and mixtures thereof. Degassing is possible from the location of the pins 24,26. After the outer skin material is injected from the gate 32, the mold is cooled by the circulation of the cooling liquid in the closed chamber 21, and the pins 24 and 26 are retracted to the position of the same horizontal plane as the mold surface. As a result, a continuous skin is cast around the core 28. To avoid the problem of irregular dimple patterns, pins 24, 26
The head simulates one dimple. After cooling, the upper mold 10 and the lower mold 12 are opened and the golf ball is taken out.

2 and 3 show an apparatus for manufacturing a golf ball without joints. The upper mold 10 and the lower mold 12 are supported and housed by surrounding mold mounting plates 15 and 16. The mounting plate 15 is a manifold 5 having a central hole 52.
It is firmly attached to 0. The central hole 52 is adapted to receive a conventional injection nozzle that opens and closes to supply molten polymer to the mold. The nozzle and manifold 50 have heating elements to keep the polymer molten during the injection cycle. Some manifolds 50 have a plurality of flow paths for supplying to a plurality of molds. The molten polymer is heated and then fed under pressure in a conventional extruder. The lower mounting plate 16 is axially movable and is mounted on a carriage 54 which is movable over a pair of spaced axial columns 56,58. Complementary positioning between the upper mold 10 and the lower mold 12 is performed by a plurality of guides with vertical bearings 60. The vertical bearing 60 receives the sliding bearings 62 around the mold while sliding. Although not shown for simplicity, a plurality of molds for molding a plurality of golf balls at a time, as generally shown in US Pat. No. 4,558,499,
They are commonly arranged on a pair of opposing supports or mounting plates. In accordance with the present invention, each pair of top and bottom molds is secured to ensure a highly accurate alignment along the score line between each pair of top and bottom molds and to prevent visible seams along the score lines. A single alignment element is installed between them. The aligning means is centered on the first axis connecting the two poles of the mold when the mold is closed, the centering means of the lower mold, and the upper mold and the lower mold in a direction generally perpendicular to the first axis. It includes a second means that allows limited movement between the molds. 1 and 2
As shown in FIG. 1, the upper mold 10 has an inwardly tapered or fastroconical shoulder or surface 40 which is concentric with the shaft 14 when the mold is closed.
The other lower mold 12 has a Fastro conical or outward taper groove or surface 42 conforming to the above, and is concentric with the shaft 14. The faces 40 and 42 are also concentric with the circular secant 22. The surfaces 40 and 42 form a space in the outward direction, and extend away from the plane 43 and the plane 45, respectively, and extend on the horizontal line of the secant. When the mold is closed, the opposing flat surfaces 43 and 45 are tightly fitted and sealed on the surface of the secant. The taper angles of the surface 40 and the surface 42 are substantially the same. Therefore, high pressure is applied to the upper die 10 before injection.
When the lower mold 12 is closed, the surfaces 40 and 42 can be preferentially locked or fitted together to align the upper mold 10 and the lower mold 12 exactly on the score line. For adjustment when a misalignment related to the shaft occurs between the upper mold 10 and the lower mold 12, the upper mold 10 and the lower mold 12 are aligned in a direction perpendicular to the shaft 14 or generally in a direction indicated by an arrow 45.
Can be moved horizontally within a limited range. This can be achieved by floating either the upper die 10 or the lower die 12 in the die supporting plate.
The cylindrical shoulders 18, 20 and the circular openings of the mold supporting plate 16 facing the shoulders 18 and 20 are fitted to each other in the vertical or diagonal direction of the lower mold 12 inside the mold supporting plate, and in the lateral or horizontal direction. Prevent movement. Providing limited clearance between opposing surfaces on the order of about 0.002 inch to about 0.008 inch allows for sufficient planar movement. The movement restricted to the direction perpendicular to the shaft 14 in response to the alignment force generated by the centering wedge fitting between the inclined alignment surfaces is slightly cramped, but the upper mold 1
Either 0 or the lower die 12 can be floated. Because the alignment at the secant can be very accurate, the outer skin of a golf ball can be molded with a high degree of precision and accuracy. In addition, the improved alignment makes it possible to supply the upper mold 10 and the lower mold 12 with no problem if the dimples cross or intersect the mold parting line. FIG. 4 is an enlarged view of the molding cavity according to the present invention. Each of the upper mold 10 and the lower mold 12 has a plurality of dimples 70 having a protrusion or a convex surface.
Is attached, and the upper die 10 and the lower die 12 are fitted to each other at a score line 22. The dimples 72, 74 are arranged close to the dividing line 22, which is a characteristic that could not be achieved by a molding method with poor accuracy. A representative golf ball 80 made from a mold according to the present invention is shown in FIG. Golf ball 80 has a plurality of concave dimples 82, but includes dimples 82a and 82b that intersect or are close to the equator or secant 84. As a result, it makes it possible to design and manufacture a golf ball 80 with dimples that are more varied than in the old ways where dimples were lacking in the even circle. Another unique advantage and result of the present invention is the ability to produce finished golf balls with the process of the present invention. After being taken out from the mold, it is not necessary to grind or paint along the seams in the next step, and the golf ball can be used in that state. Therefore, the grinding process and the paint coating process can be omitted, so that the manufacturing efficiency is improved.

[0009]

As described above, the seamless golf ball and the method and apparatus for producing the same according to the present invention have an excellent effect of preventing the formation of a joint on the outer surface of the golf ball.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a mold for a golf ball divided into two parts according to the present invention.

FIG. 2 is a vertical sectional view of a golf ball molding apparatus of the present invention.

FIG. 3 is a side view of the device illustrated in FIG.

FIG. 4 is an enlarged view of a cavity of the mold near the parting line of the mold.

FIG. 5 is a golf ball having dimples formed along a secant according to the present invention.

[Explanation of symbols]

 (10) ... Upper mold (12) ... Lower mold (34) ... Cavity (36) ... Cavity

Claims (11)

[Claims] 1. A set of an upper mold and a lower mold is fitted together and a high pressure is applied to bond a pair of the upper mold and the lower mold along a common center line forming a cavity, and a heated liquid polymer is formed. A method of manufacturing a golf ball that is injected into the cavity and then cooled to form no joints on the outer skin, and when the upper and lower molds are joined together, the inclined surfaces of the upper and lower molds are accurate. Manufacture of a seamless golf ball characterized in that the upper die and the lower die float vertically to the axis to enable centering around the axis. Method. 2. The method for producing a seamless golf ball according to claim 1, wherein the heated liquid polymer is injected to a mold location avoiding the score line. 3. The method for producing a seamless golf ball according to claim 1, wherein a heated liquid polymer is injected around the core to form a dimple-like outer skin around the core. 4. The method for producing a seamless golf ball according to claim 1, wherein the mold is opened and closed along a horizontal axis. 5. A device for forming an outer cover seamlessly on a golf ball, wherein a pair of upper and lower molds are subjected to a high pressure so that the molds are joined around a central shaft and have a score line. The plastic solution is injected into the mold to solidify, but by sloping the opposing alignment surfaces between the mold cavities and closing the mold, it looks like a wedge. The upper mold and the lower mold are accurately aligned by pushing in the periphery of the shaft and along the secant line, and one of the upper mold and the lower mold makes a limited movement in the vertical direction with respect to the shaft. A seamless golf ball manufacturing apparatus, which is capable of being aligned. 6. The seamless golf ball of claim 5, wherein the opposing alignment surfaces include an inclined surface around one die and a tapered surface around the other die. Manufacturing equipment. 7. The apparatus for producing a seamless golf ball according to claim 6, wherein the opposing alignment surfaces are concentric with the score line. 8. The golf ball manufacturing apparatus according to claim 5, wherein the inclined surface is located at a point away from the secant. 9. The liquid polymer injection port is provided at a point of the mold apart from the score line.
An apparatus for manufacturing a golf ball without the described seam. 10. A golf ball having an outer skin formed between two upper and lower dies joined on a common dividing line, wherein some of the dimples formed on the outer skin are dimples. A seamless golf ball characterized by intersecting the secant. 11. A golf ball molded between a pair of an upper mold and a lower mold fitted around a score line, the golf ball being taken out from the mold and then fitted to a position corresponding to the score line. A seamless golf ball that is free of burr and has no burr.