Abstract:
A laser is positioned relative to a rotating golf ball to remove any excess material, and if necessary to impart an aerodynamic pattern on particular areas of the golf ball, including the parting line. A preferred laser is a carbon dioxide laser. The laser beam may be de-focused to form a dimple on the parting line of the golf ball.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the manufacturing of a golf ball. More specifically, the present invention relates to a method and apparatus for manufacturing a golf ball that involves the use of a laser to primarily remove excess seam material from the golf ball. 
     2. Description of the Related Art 
     Golf balls generally have either a one-piece construction or they may comprise several layers including a core, one or more intermediate layers and an outer cover that surrounds any intermediate layer and the core. Golf balls are typically manufactured by various molding processes, whether one-component or multi-component balls. Generally, the core of the golf ball is formed by compression molding, injection molding or the like. If an intermediate boundary layer is desired, one or more intermediate boundary layers are added over the core by any number of molding operations, including casting, compression molding, and/or injection molding. The cover is then formed over the core and intermediate boundary layers, if present, through casting, compression molding, or injection molding. 
     In an injection molding process, golf balls are typically created by the injection molding of a fluid stock material around a pre-formed core. In the case of a two-component golf ball, the fluid stock material is the cover material used for the golf ball. Injection molding devices generally have two separate and mating hemispheric halves that form a cavity in which the golf ball is created. Fluid stock material is generally fed to the cavity within the mold through one or more conduits, or “runners” as they are commonly referred to in the art. The fluid stock material travelling through the runners enters the actual cavity of the mold via one or more gates. These gates are typically positioned at the parting line created between the interface of the two mold halves. Locating the gates at the parting line, however, results in unwanted material being left on the newly formed golf ball at the parting line. For example, flashing can occur along the equatorial region of the golf ball. In addition, when the gates are located at the parting line of the mold, vestigial stock material located inside the gates of the molding device is attached to the surface of the ball after the mold halves are pulled apart. Additional finishing processes are then required to remove the flashing and any excess material, which can interfere with the dimple pattern on the surface of the golf ball, thereby affecting the performance characteristics of the golf ball. 
     Similar problems arise with casting a thermosetting polymer cover on a core or multi-layer golf ball precursor product. Typical thermosetting polymer materials include polyurethanes, polyureas, polyether block amides, and the like. A thermosetting cover typically has a flash ring that is tough, and resistant to removal by conventional techniques. The use of thermosetting covers often require that the flash ring be cut prior to sanding or buffing. Additionally, the removal of the flash ring may have a deleterious result on dimples adjacent the parting line depending on the width of the parting line, and the precision of the sanding or buffing device. 
     One example of a buffing process is Reid et al., U.S. Pat. No. 4,779,387, originally filed in 1986, for a Method And Apparatus For Automatically Buffing A Golf Ball. The Reid patent discloses cutting and sanding to remove a flash ring. The sanding belt (152) of the Reid patent partially deflects about the golf ball during removal of the flash ring. 
     Another example is Takasaki, U.S. Pat. No. 4,894,958, originally filed in Japan in 1987, for an Apparatus For Scraping Off Burrs At Resin Outer Layer Of A Golf Ball. The Takasaki patent discloses a device that rotates a golf ball while a bite assembly removes the flash ring. 
     Yet another is Oka et al., U.S. Pat. No. 5,494,631, which was originally filed in Japan in 1992 for an Apparatus And Method For Manufacturing Golf Ball. The Oka patent discloses an apparatus for removing the flash ring from a golf ball that has dimples on the parting line. The Oka patent discloses using a rotating cutting member with a semi-hemispherical surface that is smaller in diameter than a dimple to remove the flash ring inside of a dimple. 
     Another example is Ihara, U.S. Pat. No. 5,554,337, which was originally filed in Japan in 1994, for Preparation Of Spherical Body. The Ihara patent discloses using an ultrasonic cutter to remove a thermoplastic flash ring from a golf ball. The Ihara patent also discloses that using a laser beam to remove a fin results in scorching of the surface of the golf ball due to laser heat. 
     The use of lasers to assist in trimming excess material from an object is also disclosed in Millerick et al, U.S. Pat. No. 5,099,101, and Picciolo et al., U.S. Pat. No. 4,539,463. The Millerick patent is for trimming excess material from semiconductor packaging, and the Picciolo patent is for trimming excess material from polyester containers. 
     A post-mold formation of dimples on a golf ball is disclosed in Oka, U.S. Pat. No. 5,190,294, which was originally filed in Japan in 1990 for a Golf Ball. The Oka patent discloses removing a flash ring, then using a heated trowel to create dimples on the seam line. 
     Consequently, there remains a need for a more efficient removal of the flash ring on a post-molded golf ball, especially one having a dimples on the parting line. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a novel method and apparatus for removing the flash ring of a recently molded golf ball. The present invention accomplishes this through the use of a laser that is positioned in relation to a golf ball that is rotated on a holder thereby allowing for the efficient removal of a flash ring. 
     One aspect of the present invention is a method for removing excess material from a golf ball. The method includes rotating a golf ball having excess material extending from a surface of the golf ball. The golf ball is rotated about an imaginary axis through each of the poles of the golf ball. Next, a laser beam is focused at the excess material substantially perpendicular to the imaginary axis. Next, the excess material is burned from the golf ball through heat from the laser beam while the golf ball is rotated about the imaginary axis. 
     Another aspect of the present invention is an apparatus for removing excess material from a golf ball. The apparatus includes a rotating means and a laser mechanism. The rotating means rotates a golf ball about an imaginary axis at a rotation of at least 5000 rotations per minute. The laser mechanism is disposed in proximity to the rotating means. The laser mechanism has a laser with a frequency of at least 500 hertz, and a nozzle for directing the laser at a golf ball disposed on the rotating means. 
     Yet another aspect of the present invention is a method for imparting a dimple pattern on a smooth surface of a golf ball. The method includes rotating the golf ball about an imaginary axis of the golf ball. Next, a laser beam is de-focused at the smooth surface. The laser beam has a frequency of at least 500 hertz and a pulse width of at least fifty microseconds. Next, a dimple pattern is burned on the smooth surface of the golf ball through heat from the de-focused laser beam while the golf ball is rotated about the imaginary axis. 
    
    
     Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a schematic side view of the apparatus of the present invention with a golf ball positioned for laser removal of its flash ring. 
     FIG. 1A is a schematic side view of the apparatus of the present invention with a golf ball positioned for de-focused laser removal of its flash ring. 
     FIG. 2 is a top plan schematic view of FIG.  1 . 
     FIG. 2A is a top plan schematic view of FIG.  1 A. 
     FIG. 3 is a schematic side view of an alternative embodiment of the present invention with the laser direct downward toward the flash ring. 
     FIG. 4 is an enlarged isolated view of FIG. 3 of the laser removing the flash ring from the golf ball. 
     FIG. 5 is a schematic top view of an alternative embodiment of the present invention with the laser directed at the edge of the golf ball. 
     FIG. 6 is a schematic top view of an alternative embodiment of the present invention with the laser directed at a forty-five degree angle to the edge of the golf ball. 
     FIG. 7 is a schematic side view of an alternative embodiment of the present invention with the golf ball tilted at an angle to the laser. 
     FIG. 8 is a side view of a golf ball prior to laser formation of dimples on the parting line of the golf ball. 
     FIG. 9 is a side view of the golf ball of FIG. 8 during laser formation of dimples on the parting line of the golf ball. 
     FIG. 10 is a side view of the golf ball of FIG. 8 after laser formation of dimples on the parting line of the golf ball. 
     FIG. 11 is an enlarged view of the de-focused laser removing flash ring material from the golf ball to form a dimple. 
     FIG. 11A is an enlarged view of the focused laser removing flash ring material from the golf ball to form a dimple. 
     FIG. 12 is a top view of a smooth surface golf ball prior to laser formation of a dimple pattern thereon. 
     FIG. 13 is a top view of the golf ball of FIG. 12 during laser formation of a dimple pattern thereon. 
     FIG. 14 is a top view of the golf ball of FIG. 12 after laser formation of a dimple pattern thereon. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIGS. 1-7, an apparatus for laser removal of excess material from a recently molded golf ball is generally designated  19 . A golf ball  20  has excess material  22 , such as a flash ring, due to molding techniques that force excess material outward along the parting line of the mold halves that are used to form the cover of the golf ball  20 . Cover molding techniques include casting, compression and injection molding techniques. The excess material  22  is retained on the golf ball  20  in the form of a flash ring, projections or the like. 
     The cover of the golf ball  20  will have a plurality of dimples  24  thereon that form the aerodynamic pattern of the golf ball  20 . The golf ball  20  may be “mapped” as having a pair of poles  26  and an equator  28 . The excess material  22  usually lies at the equator  28  since most parting lines are aligned with the equator  28  of the golf ball  20 . An imaginary axis  30  is positioned through the poles  26  of the golf ball  20 . 
     A laser mechanism  32  is positioned relative to the golf ball  20  to effect removal of the excess material  22  through use of a laser beam. The laser mechanism  32  has a housing  34  with a convergence lens  36  that directs a laser beam  38  toward the excess material  22 . The laser mechanism is movable along x, y and z axes in relation to the golf ball  20 . In one embodiment, the laser beam  38  has a focal point  40  and is considered focused for removal of excess material  22 . In an alternative embodiment, the laser beam  38   a  converges in front of the golf ball  20  and is considered de-focused. The golf ball  20  is rotated in a rotating holder  50  during the removal process. In a preferred embodiment, the golf ball  20  is rotated about the imaginary axis  30  through the poles  26 . The golf ball  20  will be seated so as to position the excess material  22  for removal by the laser beam  38 . Thus, the excess material  22  should not lie within the rotating holder  50 . 
     A preferred embodiment as shown in FIGS. 1 and 2 has the laser beam  38  focused directly at the excess material  22  in a horizontal plane with the equator  28  of the golf ball  20 . In this embodiment, the laser beam  38  burns away the excess material  22  as the golf ball  20  is rotated on the holder  50 . The power of the laser beam  38  is controlled to prevent scorching or other deleterious effects to the surface of the golf ball  20 . Thus, only the excess material  22  is burned away while the desired surface of the golf ball  20  is untouched by the laser beam  38 . 
     An alternative embodiment shown in FIGS. 1A and 2A has the laser beam  38   a  defocused at the excess material  22  of the golf ball  20  to remove the excess material and form a plurality of dimples  24  on the parting line/equator  28  of the golf ball  20 . The de-focused laser beam  38   a  has a convergence point  39  in front of the golf ball  20 . The de-focused laser beam  38   a  has the highest energy at its center and lower energy outward from the center allowing for the forming of a dimple  24  with a greatest depth at its center. The de-focused laser is explained in greater detail below. 
     A preferred laser is a carbon dioxide laser such as available from Convergent Energy of Sturbridge, Mass. The laser has a frequency of between 400 and 2000 Hertz, more preferably between 500 and 1500 Hertz, and most preferably 1000 Hertz. The pulse width of the laser is between 30 and 100 microseconds, more preferably 50 and 75 microseconds, and most preferably 70 microseconds. The laser mechanism  32  has a nozzle  33 , not shown, that has a diameter of 0.6 inches for focusing the laser beam  38 . The laser mechanism  32  also has a source of gas to assist the laser beam  38  in removing the excess material  22 . The gas is preferably air or nitrogen, however, those skilled in the pertinent art will recognize that other similar gases may be utilized without departing from the scope and spirit of the present invention. The gas is preferably released at a pressure of twenty pounds per square inch. 
     FIGS. 3 and 4 illustrate an alternative embodiment of the present invention wherein the laser mechanism  32  is mounted above the golf ball  20  for trimming of the excess material  22  therefrom. In this embodiment, the laser beam  38  trims the excess material  22  as the golf ball  20  is rotated at a predetermined rate. The focal point  40  is positioned at the edge of the desired surface of the equator  28  or parting line of the golf ball  20  to burn the excess material  22  adjacent the surface of the golf ball  20 . 
     FIGS. 5-7 illustrate yet further embodiments of the placement of the laser mechanism  32  relative to the golf ball  20 . In FIG. 5, the laser mechanism  32  is positioned at the edge of the golf ball  20  to burn away the material as the golf ball is rotated on the holder  50 . In FIG. 6, the laser mechanism  32  is positioned forty-five degrees to the edge of the golf ball  20  to remove the excess material  22 . In FIG. 7, the golf ball  20  is tilted within the holder  50  relative to the laser beam  38  to remove the excess material  22 . Those skilled in the pertinent art will recognize that a de-focused beam  38   a  may be used with the embodiments illustrated in FIGS. 3-7 without departing from the scope and spirit of the present invention. 
     In yet another embodiment shown in FIGS. 8-11, the present invention is utilized for laser formation of dimples  24  on the equator  28  or parting line of the golf ball  20 . In FIG. 8, the golf ball  20  has a flash ring on its parting line. As the golf ball  20  is rotated, the de-focused laser beam  38   a  forms a dimple  24  on the surface of the golf ball  20 . As shown in FIG. 11, the center  57  has the highest energy with outward concentric regions  57  and  58  having lower energy levels allowing for the greatest depth of the dimple  24  to be formed in the center with lower depths toward the surface as with mold-formed dimples. Alternatively as shown in FIG. 11A, the power of the focused laser beam  38  is adjusted to repeat a desired contour pattern of a dimple  24 . Using either method, the laser beam  38  or  38   a  directs anywhere from 100 to 2000 pulses per dimple  24  to form the dimple  24  with the predetermined diameter, contour, depth, edge radius, and the like. Thus, the present invention allows for the post-molding formation of dimples  24  on the parting line of a golf ball  20 . 
     FIGS. 12-14 illustrate yet another embodiment of the present invention. In FIG. 12, a golf ball  20 ′ with a smooth surface  51  is provided. The surface material may be composed of a polyurethane, ionomer, or similar polymer surface. In FIG. 13, the golf ball  20 ′ has undergone partial laser formation of an aerodynamic pattern thereon. In this example, dimples  24  have been laser formed on part of the smooth surface  51 , however, those skilled in the relevant art will recognize that other aerodynamic patterns may be laser formed on the golf ball. Finally, FIG. 14 illustrates a completed aerodynamic pattern that is laser formed on the golf ball  20 . 
     From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.