Golf ball finishing method

Abstract

A method of removing parting line flash from a molded golf ball by use of low temperature cryogenic deflashing apparatus is disclosed. The cryogenic deflashing apparatus incorporates a rotating basket wherein the golf balls are placed and therein agitate them such that each ball will be evenly exposed to a recirculating blasting media. The low temperature environment causes the very thin gauge (0.003″) parting line flash to become embrittled relative to the ball and is deflashed by the blasting media, which comprises plastic pellitized shot.

Description

FIELD OF THE INVENTION

[0001] The invention relates to an improved method for finishing the surface of golf balls. More specifically, the improvement is directed to the removal of parting line flash from molded golf balls by a cryogenic deflashing apparatus.

BACKGROUND OF THE INVENTION

[0002] Conventional golf balls can be divided into two general types or groups: solid balls and wound balls. The difference in play characteristics resulting from these different types of construction can be quite significant.

[0003] Balls having a solid construction are generally most popular with the average recreational golfer because they provide a very durable ball while also providing maximum distance. Solid balls are generally made with a single solid core, usually made of cross-linked rubber, which is encased by a cover material. Typically the solid core is made of polybutadiene which is chemically cross-linked with zinc diacrylic and/or similar cross-linking agents and is covered by a tough, cut-proof blended cover. The cover is generally a material such as SURLYN®, which is a trademark for an ionomer resin produced by DuPont. Wound balls typically have either a solid rubber or liquid center core around which many yards of stretched elastic are wound. Wound balls are generally softer and provide more spin, which enables a skilled golfer to have control over the ball's flight and final position.

[0004] Regardless of the form of the ball, players generally seek a golf ball that delivers the best combination as to maximum distance, spin and durability. Golf ball manufacturers are continually searching for new ways in which to provide golf balls that deliver the maximum performance for golfers at all skill levels.

[0005] The outer cover of either type golf ball are formed with various materials that may be urethane elastomers, Balata, ionomers or any other appropriate materials. The cover surfaces are formed with dimples of various numbers, sizes and patterns, which improve flight distance, control and stability. The outer surface of the ball covers usually have the manufacturers indicia disposed thereon as well as an application of a paint or clear coat for the purposes not only of good appearance but also of improving fight distance and protecting of the indicia imprinted thereon.

[0006] The process of molding a cover over a golf ball subassembly usually produces a golf ball having a parting flash line, i.e. the area adjacent the interfacing mold surfaces. Such residual flash is not only aesthetically objectionable, but additionally functionally objectionable, and therefore must be removed, i.e. deflashed, from the article prior to use of the same. It has been necessary to perform a buffing or finishing step to remove this flash. The prior art method of removing the flash is to employ mechanical cutting blades and sandpaper. This method requires a high level of intervention due to belt and blade wear and also requires precise orientation of the subassembly on the buffing equipment. A method of finishing golf balls in a bulk process without the need for mold orientation of balls is highly desired.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to an improved method of removing parting line flash from a golf ball component following the molding of a layer on a ball subassembly. The process is preferably used for deflashing golf balls after the cover layer has been molded onto the ball subassembly. The process is most preferably used for non-planar parting lines. The invention allows for golf ball coponents to be bulk loaded into a cryogenic chamber where the temperature of the ball is reduced by liquid nitrogen. Operating temperatures are typically below −100° F. Because of the thin gauge of the parting line flash relative to the layer thickness, (the gauge of the flash generally only about 0.003 inches) the flash becomes embrittled in comparison to the layer. The chamber contains a rotating tumbler to agitate and expose the golf ball components during the flash removal cycle. As the chilled product rotates a plastic media is delivered at high velocity which further enhances the flash removal process.

[0008] The present invention provides for the removal of flash lines in a batch method therein eliminating the need for orienting each golf ball prior to deflashing, and also eliminating the need for orientation tabs.

[0009] The present invention reduces the maintenance and downtime due to changing and replacing sanding belts and cutting blades.

[0010] Batch buffing allows for bulk loading and unloading thereby simplifying the material handling process.

[0011] The present invention allows for easier finishing of varying symmetry of parting lines and dimple patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 describes a process flow chart for the present invention's method for golf ball finishing.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] The present invention applies to all thermoplastic or thermoset layers on golf balls that require finishing or removal of flashing that accrues from the molding of the layer on a golf ball subassembly.

[0014] In the manufacture of golf balls, flash lines are routinely removed by mechanical buffing procedures in which mechanical cutting blades and sand paper are utilized as a buffing medium. The orientation of the ball is of primary importance for the buffing step. Orientation tabs are typically molded into the ball to accommodate this requirement. The replacement of belts and blades adds to the significant intervention required for these procedures. With the advent of future golf balls having irregular flash lines (non-planar), there is a strong need for a method for removing the flash without having to orient the balls for a buffing process. The present invention utilizes a cryogenic process that does not require orientation of the golf balls in order for the flash to be removed, and also eliminates the need for sandpaper and cutting blades.

[0015] FIG. 1 displays a flow chart wherein golf balls are moved from compression mold racks by automatic transport to a bulk die-out. From there they are transported to a cryogenic apparatus and placed into a stainless steel parts basket of the apparatus. The parts basket rotates in a blast chamber evenly exposing all golf balls to the blast media. The chamber is insulated with rigid polyurethane foam to ensure stable temperatures. Liquid nitrogen lowers the interior temperature, freezing the flashing to make it brittle. Use of high purity, moisture-free nitrogen eliminates the need for a dryer and prevents part contamination due to moisture. A high speed impeller introduces a blasting media typically comprising pellitized shot. Operating temperatures are typically below −100° F., preferably in a range between about −100° F. to about −220° F., and more preferably about −190° F. The process time is about ten minutes.

[0016] The parting line flash is of a rather thin gauge (0.003 inches) relative to the thickness of the molded cover, and therefore only the parting line flash becomes embrittled in the low blasting media stream. By controlling the exposure duration of the molded golf balls within the cryogenic environment, as well as the velocity and dispersion of the deflashing media against them, it has been found that satisfactory golf ball deflashing may be accomplished, typically at a substantial reduction over sanding deflashing operations. After the flashing has been removed the balls are bulk unloaded for further processing. Acceptable cryogenic equipment includes machines such as those manufactured by Cryogenic Deflashing Systems, Inc. of Santa Ana, Calif., and based upon the teachings of U.S. Pat. No. 4,979,338, which is incorporated by reference herein in its entirety.

Claims

1. A method for removing parting line flash from golf balls, the method comprising:

loading a plurality of golf ball components with flash into a rotating tumbler within a cryogenic chamber;

agitating the tumbler to expose the surfaces of the golf ball components;

lowering temperature in the chamber to less than about −100° F.;

introducing plastic media into the chamber to remove the flash; and

removing the golf ball components from the chamber.

2. The method of claim 1, wherein the step of lowering the temperature of the chamber is by the introduction of high-purity, moisture-free liquid nitrogen into the chamber.

3. The method of claim 2, wherein the lowering of the temperature in the chamber is to a temperature of between about −100° F. and about −220° F.

4. The method of claim 1, wherein the plastic media are particles with an average diameter less than about xxx inches.

5. The method of claim 1, wherein the golf ball components are exposed for less than xxxx minutes.

6. A golf ball produced by the method of claim 1.