KR930006940B1 - Monolithic short-range golf ball - Google Patents

Abstract

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Description

Monolithic short-range golf ball

1 is a front view of a one-piece short-range golf ball according to an embodiment of the present invention,

2 is a cross-sectional view taken along line 2-2 of FIG. 1,

3 is a front view of a golf ball according to another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10, 110: golf ball 12: thermoplastic material

14 surface 16: radius

20: center 22: shell

24: core portion 26: boundary portion

28: home 128: hump

The present invention relates to a short distance golf ball, more specifically, to a monolithic body having an operating characteristic comparable to that of a conventional golf ball, except that it is used at a distance of 30-70% shorter than a conventional golf ball. A short distance golf ball.

A typical 18 hole golf course occupies an area of about 180 acres (728,424 m 2). In the resorts and metropolitan areas where golf courses are often created, the problem of securing the required land and the issue of land prices makes it desirable to design a golf course that can take up a fairly small area and play all the competition of a typical golf course. It's work. By providing a short distance golf ball used at a distance of approximately 50% of a conventional golf ball's flight distance, the land required for the golf course can be reduced by 67-50%.

In order to allow golfers to not only perform regular training and practice, but also to enjoy the enjoyment of playing golf with a normal golf ball on a normal course, a short distance golf ball should normally be about 50% shorter except that its flight distance must be shorter. It must be operated in a manner substantially similar to the golf ball. In order to be comparable to a normal golf ball, a short-range golf ball must be easy to operate during a game, which means that a golfer may hit a high or low short-range golf ball, or hit or slam a ball, as with a regular golf ball, This means you should be able to pull or curve the curve.

In addition, the short-range golf ball should operate essentially the same as a conventional golf ball when hit by a putter on the green. In addition, the golfer may allow the short-range golf ball to "bite" or "hold" the green to the same extent as would be possible on a conventional golf ball when the short-range golf ball is hit in the same manner as a conventional golf ball. It should be possible to impart sufficient backspin to short-range golf balls when properly hit by a medium or short iron. The short-range golf ball should act as a flying and green houlding in the same way as a normal golf ball when hit from a sand bunker.

던 것과 동일한 즐거움을 가지는 동일한 연습 및 훈련을 할 수 있다.If a short-range golf ball has the above characteristics, a golfer can play a short-range golf ball on a short golf course, use all clubs, and about half of a golf course in about half of a typical golf course area. In time, relaxing at the usual golf course

You can do the same exercises and drills with the same fun as you did.

The present inventors have found that short distance golf balls with the above characteristics cannot be obtained only by reducing the elasticity of a conventional golf ball to reduce the initial speed of the ball leaving the club. This "deadball" achieves the lift necessary to provide the same trajectory as a typical golf ball weighing about 45g, even though it has a special aerodynamic groove structure to maximize lift. can not do.

Accordingly, an object of the present invention is to provide a short distance golf ball that provides essentially the same operating characteristics as a conventional golf ball and is used on a shortened golf course except that the playing distance is 30-70% shorter than that of a conventional golf ball. To provide.

The inventors have found that in order to achieve such an object, it is easy to spin in terms of the club, requires less gravity to overcome, and a lighter golf ball than a conventional golf ball. In order to produce such short-range golf balls, a single golf ball is formed from thermoplastic material that is light enough (low specific gravity) while possessing elasticity capable of flying properly and stiffness that withstands the impact of standard clubs without permanent deformation.

This thermoplastic material comprises a polymer and fine glass bubbles. Glass bubbles are evenly distributed throughout the thermoplastic polymer and fill the interstices of the thermoplastic polymer.

Monolithic short-range golf balls of the present invention are prepared by mixing thermoplastic polymer and glass bubbles with a chemical blowing agent and injecting the mixture into a golf ball-shaped mold cavity. By controlling the amount of mixture injected, the amount of blowing agent and other process parameters, the monolithic golf ball produced has a dense shell and cellular core adjacent its outer surface. The thickness of the shell of the golf ball determines the moment of inertia of the golf ball. Of course, the moment of inertia of the golf ball determines how many spins can be given to the golf ball when hit by the golf club.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1, another golf ball 10 is shown in one embodiment of the present invention. The golf ball 10 has a diameter of about 4.27 cm (about 1.68 inches), the same size as a conventional golf ball, and the weight is about 15-30 g compared to about 45 g of a conventional golf ball. This golf ball 10 is a monolithic golf ball made of thermoplastic material 12. The golf ball 10 is molded by injection molding together with a chemical blowing agent. The method of injection molding a golf ball and the exact composition of the thermoplastic will be described in more detail below.

Referring to FIG. 2, the cross section of the golf ball 10 indicates that the density of the thermoplastic material 12 increases along the radius 16 of the golf ball from the center 20 to the surface 14. The golf ball 10 has an outer dense (high density) shell 22 that is about 0.32 cm-1.59 cm (0.125-0.625 inches) thick.

The thickness of the shell is inversely proportional to the amount of blowing agent used to make the golf ball and is preferably about 0.64 cm (0.25 inch). The core portion 24 of the golf ball 10 has a foamed cellular structure. The boundary 26 between the cellular core 24 and the shell 22 is not clearly outlined, but can be observed by examining a cross-sectional sample of a golf ball made in accordance with the present invention.

The golf ball 10 has dimples 28 (FIG. 1) formed by the pattern of the mold during the injection molding process. The grooves 28 are formed in the surface 14 in a conventional groove placement manner that can be used in golf balls of a conventional grooved shape. However, in a preferred embodiment, golf ball 110 having a bramble pattern, as shown in FIG. 3, has bumps 128 on the surface instead of grooves, where the golf ball It helps me to resist the effects of the wind when I carry me. The grooved golf ball 10 and the humped golf ball 110 are finished in a conventional manner by painting the golf ball in white, yellow, orange or other suitable color.

Depending on the weight and density distribution of the thermoplastic material in the golf ball of the present invention, the golf ball of the present invention operates in much the same way as a conventional golf ball, except that the playing distance of the golf ball is shorter than that of the conventional golf ball. . Short range golf balls of the present invention have a bounce rate of about 50-80%, preferably 67%. In addition, the golf ball has a compressibility of 0-100 as measured by an Atti compression tester, and the compressibility is preferably 60.

The thermoplastic material constituting the golf ball 12 includes a thermoplastic polymer in which fine organic glass bubbles are uniformly distributed throughout the polymer gap. Ionomer resins suitable for making this thermoplastic polymer are sold by the DuPont Company, Delaware, USA under the trademark "SURLYN". A "serine" resin is obtained with zinc ion copolymers and sodium ion copolymers. It is found that individual copolymers are useful for carrying out the present invention, and mixtures of the two copolymers are likewise useful for carrying out the present invention.

As mentioned above, the thermoplastics comprise fine glass bubbles that act as fillers or extenders. In the finished product, the glass bubbles are evenly distributed throughout the thermoplastic polymer. Glass bubbles useful in carrying out the invention are manufactured by 3M Company, Minnesota, USA, and have a density of 0.12-0.18 g / cm 3. Other inorganic fillers such as titanium oxide or calcium carbonate can be used to make the short range golf balls of the present invention. Glass bubbles are preferred because they improve the impact resistance by acting as a fine shock absorber to dissipate energy to help shorten the ball's flight distance.

In order to produce a golf ball of the above composition having the above physical properties and operating characteristics, the golf ball is made by injection molding together with a foaming agent. Conventional blowing agents such as freon, nitrogen gas and carbon dioxide can be used with the "serine" resin. Suitable chemical blowing agents to carry out the invention have a decomposition temperature in the range of about 110-224 ° C. (230-435 ° F.). Two preferred chemical blowing agents are sold under the trademarks "Celogen TSH" and "Cellogen RA" at Uniroyal Chemical, Connecticut, USA. Foam concentrates sold under the trademark "Norteck" in the Northern Petro Chemical Company of Mesa-Fusets, USA may also be used.

Although this manufacturing process can be performed at a wide range of blowing agent decomposition temperatures, higher decomposition temperatures are preferred because the risk of premature expansion can be minimized. Therefore, the decomposition temperature is preferably 177-232 ° C. (350-450 ° F.).

The following composition has been shown to provide an acceptable golf ball having a shell about 0.64 cm (about 0.250 inch) thick and having the physical and operating characteristics required for a short golf ball.

The thickness of the shell of the finished golf ball is inversely proportional to the amount of blowing agent.

For example, reducing the amount of "Cellogen TSH" to 0.50 parts by weight results in a thickness of about 1.3 cm (about 0.500 inches) of the shell of the finished golf ball. Thus, the thickness of the shell portion in the 0.50-2.00 parts by weight of the blowing agent is about 1.3-0.32 cm (about 0.500-0.125 inches).

The weight of the filler in the composition may vary within the range of 0.5-15 parts by weight, and the weight of the glass bubbles may range from 0-10 parts by weight.

In order to produce the short-range golf ball of the present invention, the components of each composition are first mixed into yarns before injection molding.

Conventional screw injection molding machines used to make conventional two-piece golf balls must be adapted for foam molding as follows. The injection nozzle is provided with a shutoff valve so that only a predetermined amount of the mixture is injected into each mold cavity. In particular, it is preferable to inject only about 15-30 g of the mixture to the grooved golf ball 10. Alternatively, for the golf ball 110 in the shape of the excitation, 15% more (about 17-35 g) of the mixture may be injected to produce a golf ball 15% heavier than the grooved golf ball 10. The injection molding machine should generate sufficient injection pressure to be able to inject the material into the mold cavity within 1 second or faster to minimize premature gas expansion. In addition, the flow channel should be short and provide equal distance flow to the ends of the mold cavity so that each shaped golf ball has a uniform shell thickness.

In order for the manufactured short-range golf ball to have a suitable shell thickness, it is important that the process parameters are adjusted. The initial temperature of the mixture is room temperature. The mold cavity is cooled to about 4-21 ° C (about 40-70 ° F) with about 4 ° C (40 ° F) water. The injection cylinder has a temperature gradient along its length to the nozzle. The back of the cylinder is kept at a low temperature (about 163 ° C. (about 325 ° F)) to reduce premature gas expansion, and the nozzle is held at a high temperature (about 204 ° C.) to facilitate rapid injection by reducing the viscosity of the mixture. Approximately 400 ° F)). The mold is then kept closed for 60-240 seconds (depending on the thickness of the shell) while maintaining the mold temperature at about 4-21 ° C. (about 40-70 ° F.). This process requires about 60 seconds for a shell thickness of 0.32 cm (0.125 inch) to allow the shell to be fully molded before opening the mold. After a predetermined time has elapsed, open the mold and immediately after removing the golf ball, cool it with cold water to prevent any further foaming.

By mixing the required amount of blowing agent and adjusting the process within the parameters described above, the density of the thermoplastics forming the short golf balls allows the desired shell thickness to provide the operating characteristics required for the short golf balls.

The best results were achieved with the following process parameters for a golf ball having a shell thickness of about 0.64 cm (about 0.250 inch) and made from the mixture specified in Examples 1-9.

Although the golf ball 10 of FIG. 1 having a standard groove pattern shows proper performance under most race conditions, the flight characteristics of the golf ball 10 having grooves under windy conditions are different from those of a normal golf ball. This is because the weight of this golf ball 10 is 15-30g, which is lighter than 45g, which is the weight of a normal golf ball.

The flight characteristics of the golf ball 10 under the windy state can be improved by changing the groove pattern of the golf ball 10 to a "bramble" pattern as in the golf ball 110 of FIG. The bramble pattern shown in FIG. 3 has no grooves at all, and in fact has 398 humps 128.

The 398 humps in the Thorn pattern are approximately 0.025 cm (0.01 inches) high in the first row adjacent to the protruding band, 0.046 cm (0.018 inches) high in the second row, and 0.076 cm (0.030 cm) high in the rest. Inches) or more. The humps are arranged in a tetrahedron pattern (a polyhedron with 24 sides), the geometry of which is a conventional golf ball (e.g., a golf ball as "Muirfield" manufactured by McGregor Golf Company). It is identical to the geometric shape used for the grooves of. The protruding band 130 is not critical to the improved flight characteristics of the golf ball in the form of a hump, it is provided only to smooth the seam left by the molding process.

By adding a bramble pattern to the golf ball, the golf ball 110 has a relatively higher drag than the grooved golf ball 10. As a result, by increasing the weight of the golf ball 110 having a hump about 15% of the weight of the golf golf course 10, the golf ball having a groove having a low distance and light flight distance (10) It turned out to be about the same. The weight of the golf ball with the hump is preferably about 17-35g.

Since the golf ball 110 with the hump is about 15% heavier than the grooved golf ball 10, its trajectory is not as affected by the wind as the light golf ball 10 with grooves. Surprisingly, golf balls with humps with rough surfaces, relatively high drag and turbulent air flow at the ball's surface at low speeds are less affected by the wind than smooth golf balls with grooves in flight.

In addition, the thorn tree pattern appears to eliminate the sudden change from the high speed turbulent air flow across the golf ball to the low speed laminar air flow, resulting in a stable flight of the golf ball with the humps, especially in windy conditions. (Hence, a ball with a lump does not fly like a knuckle ball).

The thorn pattern on the golf ball 110 is produced by a mold having a complementary surface shape.

Claims (5)

A golf ball consisting of a foamed thermoplastic polymer and a filler, the golf ball having a density gradient that increases from the center to the surface of the golf ball along a radius, wherein the surface is shaped as having a hump. ball. The unitary short-range golf ball according to claim 1, wherein the density gradient is provided by the structure of the dense outer shell part and the cellular core part. The unitary short-range golf ball according to claim 2, wherein the shell portion has a thickness of 0.32 cm-1.59 cm (0.125-0.625 inches). The monolithic short-range golf ball of claim 2, wherein the filler is fine glass bubbles uniformly distributed throughout the thermoplastic polymer. The golf ball according to claim 1 or 2, wherein the thermoplastic polymer comprises 100 parts by weight of the golf ball, the filler comprises 0.5-15 parts by weight of the golf ball, and the golf ball has a diameter of 4,23 cm (1, 68-inch), weighing 17-35g, one-piece short-range golf ball.

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