Abstract:
A method and assembly for molding golf balls is disclosed herein. The invention includes an injection mold assembly ( 20 ) with a first mold half ( 22   a ) having a plurality of cavities and at least one locating pin ( 92 ) and a second mold half ( 22   b ) having a plurality of cavities and at least one aperture for engagement with at least one bushing ( 94 ) and a spring ( 250 ) for exerting a lateral force against the second mold half ( 22   b ). Preferably, the locating pin has a first taper section ( 93 ) and a second taper section ( 95 ). Preferably, the bushing ( 84 ) has a first cavity  1 ( 1150  and a second cavity ( 117 ).

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and method for de-molding a golf ball from a mold cavity. 
   2. Description of the Related Art 
   Golf balls may comprise one-piece constructions or they may include several layers including a core, one or more intermediate layers and an outer cover that surrounds any intermediate layer and the core. In multi-component golf balls, there exists an inner core. Often, this core is made by winding a band of elastomeric material about a spherical elastomeric or liquid-filled center. Alternatively, the core may be a unitary spherical core made of a suitable solid elastomeric material. One such material that is conventionally used for the core of golf balls is a base rubber, such as polybutadiene, which is cross-linked with a metal acrylate, such as zinc diacrylate. 
   In the construction of some multi-component golf balls, an intermediate boundary layer is provided outside and surrounding the core. This intermediate boundary layer is thus disposed between the core and the outer cover of the golf ball. 
   Located outwardly of the core and any intermediate boundary layer is a cover. The cover is typically made from any number of thermoplastic or thermosetting materials, including thermoplastic resins such as ionomeric, polyester, polyetherester or polyetheramide resins; thermoplastic or thermoset polyurethanes; natural or synthetic rubbers such as balata (natural or synthetic) or polybutadiene; or some combination of the above. 
   The cover may be injection molded, compression molded, or cast over the core. Injection molding typically requires a mold having at least one pair of mold cavities, e.g., a first mold cavity and a second mold cavity, which mate to form a spherical recess. In addition, a mold may include more than one mold cavity pair. 
   In one exemplary injection molding process each mold cavity may also include retractable positioning pins to hold the core in the spherical center of the mold cavity pair. Once the core is positioned in the first mold cavity, the respective second mold cavity is mated to the first to close the mold. A cover material is then injected into the closed mold. The positioning pins are retracted while the cover material is flowable to allow the material to fill in any holes caused by the pins. When the material is at least partially cured, the covered core is removed from the mold. 
   As with injection molding, compression molds typically include multiple pairs of mold cavities, each pair comprising first and second mold cavities that mate to form a spherical recess. 
   Although the prior art has disclosed many methods of manufacturing golf balls, the prior art has failed to provide an efficient manufacturing process at a lower cost. The present invention overcomes the increased costs of the prior art by implementing an improved injection mold and de-molding process for a lower cost mass production process. 
   BRIEF SUMMARY OF THE INVENTION 
   One aspect of the present invention is an injection mold assembly for golf balls which includes a first mold half, a second mold half and a spring for exerting a lateral force against the second mold half during disengagement of the first mold half from the second mold half. The first mold half has a plurality of cavities and a first pin having a base with a first diameter and a first taper section with a diameter smaller than the first diameter. The second mold half as a plurality of cavities and a first business for engagement with the first pin of the first mold assembly. The first bushing has a main cavity with a first diameter and a first cavity with a diameter smaller than the diameter of the main cavity. 
   Another aspect of the present invention is a method for de-molding a plurality of golf balls or golf ball precursor products from an injection mold assembly. The method beings with injecting a polymer material into a plurality of cavities of a mold to form a layer for a golf ball. Next, a lateral force is exerted on the second mold half. Next, the first mold half is separated from the second mold half. Next, the second mold half is laterally displaced from the first mold half. 
   Having briefly described the present invention, the above and further objects, feature 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 side view of a mold assembly of the present invention 
       FIG. 2  is a top plan view of the first mold half of the mold assembly of  FIG. 1 . 
       FIG. 3  is a side plan view of the first mold half of  FIG. 2 . 
       FIG. 4  is a top plan view of a second mold half of the mold assembly of  FIG. 1 . 
       FIG. 5  is a side plan view of the second mold half of  FIG. 4 . 
       FIG. 6  is an isolated view of a preferred embodiment of a locating pin of the present invention. 
       FIG. 6A  is top plan view of the locating pin of  FIG. 6 . 
       FIG. 6B  is top perspective view of the locating pin of  FIG. 6 . 
       FIG. 7  is an isolated view of an alternative embodiment of a locating pin of the present invention. 
       FIG. 7A  is top plan view of the locating pin of  FIG. 7 . 
       FIG. 7B  is top perspective view of the locating pin of  FIG. 7 . 
       FIG. 8  is an isolated view of a bushing of the present invention. 
       FIG. 8A  is top plan view of the bushing of  FIG. 8 . 
       FIG. 9  is an exploded view of a pair mold inserts and golf ball precursor product utilized for the mold assembly of the present invention. 
       FIG. 10  is a side view of a mold assembly as utilized within an injection molding machine. 
       FIG. 11  is a top plan view of the second mold half and spring assembly of the present invention. 
       FIG. 12  is an isolated view of a locating pin within a bushing of the mold assembly of the present invention at the beginning of the separation of the first mold half from the second mold half during a de-molding process. 
       FIG. 13  is an isolated view of a locating pin within a bushing of the mold assembly of the present invention at an intermediate step of the separation of the first mold half from the second mold half during a de-molding process. 
       FIG. 14  is an isolated view of a locating pin within a bushing of the mold assembly of the present invention near the end of the separation of the first mold half from the second mold half during a de-molding process. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIGS. 1-5 , a mold assembly for injection molding a layer of a thermoplastic material on a golf ball precursor product is generally designated  20 , and is composed of a first mold half  22   a  and a second mold half  22   b . In a preferred embodiment, the first mold half  22   a  is the top mold half and the second mold half  22   b  is the bottom mold half. The mold halves  22   a - b  are mated together during the injection molding process. 
   Referring again to  FIGS. 1-5 , each mold half  22   a - b  is generally composed of a solid body  70 . Each body  70  is preferably composed of a metal material, and most preferably composed of stainless steel. Each of the mold halves  22   a - b  preferably has a plurality of insert apertures  33  for preferably housing each of a plurality mold inserts  30 . Preferably, the insert apertures  33  each have a diameter that ranges from 2.00 inches to 3.00 inches, and the diameter of each insert aperture is preferably larger than the diameter of the corresponding mold insert  30 . 
   The first mold half  22   a  preferably has a plurality of locating apertures  74   a - d  at each corner. A plurality of locating pins  92   a - b  are preferably mounted within two of the plurality of locating apertures  74   a - d . In a most preferred embodiment, locating pin  92   a  is mounted within locating aperture  74   a  and locating pin  92   b  is mounted within locating aperture  74   d.    
   The second mold half  22   b  preferably has a plurality of locating apertures  74   f - h  at each corner. A plurality of locating bushings  94   a - b  are preferably mounted within two of the plurality of locating apertures  74   f - h . In a most preferred embodiment, locating bushing  94   a  is mounted within locating aperture  74   g  and locating bushing  94   b  is mounted within locating aperture  74   f.    
   The locating pins  92   a - b  and locating bushings  94   a - b  properly align the mold halves  22   a - b  during mating thereof to form the mold assembly  20 . In a preferred embodiment, each of the plurality of locating pins  92   a - b  is diagonally opposed to each other on the first mold half  22   a , and each of the plurality of locator bushings  94   a - b  is diagonally opposed to each other on the second mold half  22   b.    
   As shown in  FIGS. 6 ,  6 A and  6 B, a preferred embodiment of the locating pin  92  has a first taper  93  section, a second taper section  95 , a base  99  and a base flange  101 . The locating pin  92  preferably has a flat top  107 . The base flange  101  has a shoulder  105  to lock the locating pin within an aperture  74 . The base  99  has a shoulder  103 . The first taper section  93  is preferably tapered at an angle, α T1 , ranging from 30 to 70 degrees relative to the shoulder  103  of base  99 , and most preferably tapered at an angle of 45 degrees relative to the shoulder  103  of the base  99 . The second taper section  95  is preferably tapered at an angle, α T2 , ranging from 50 to 85 degrees relative to the shoulder  103  of base  99 , and most preferably tapered at an angle of 75 degrees relative to the shoulder  103  of the base  99 . 
   Each locating pin  92  has a length Lp preferably ranging from 1.5 inches to 4.0 inches, and most preferably a length of 2.3 inches. The base flange  101  has a length, “Lf”, preferably ranging from 0.025 inch to 0.500 inch, and most preferably from 0.175 inch to 0.200 inch. The base  99  has a length, “Lb”, preferably ranging from 0.75 inch to 2.0 inches, and most preferably a length of 1.25 inch. The second taper section  95  has a length, “L T2 ”, preferably ranging from 0.100 inch to 0.500 inch, and more preferably from 0.200 inch to 0.300 inch. The first taper section  93  has a length, “L T1 ”, preferably ranging from 0.250 inch to 1.00 inch, and most preferably from 0.500 inch to 0.750 inch. 
   As shown in  FIG. 6A , the base flange  101  has a radius, “R F ”, preferably ranging from 0.500 inch to 1.00 inch, and most preferably 0.75 inch to 0.90 inch. The base  99  has a radius, “R B ”, preferably ranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to 0.70 inch. The second taper section  95  has a radius, “R T2 ”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. The second taper section  95  has a radius, “R T2 ”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. R T1  and R T2 , respectively, represent the largest radius of the first taper section  93  and the second taper section  95 . The radius, if measured at other locations along each of the tapered section  93  and  95  will be smaller than R T1  and R T2 . 
   In an alternative embodiment shown in  FIGS. 7 ,  7 A and  7 B, the locating pin  92 ′ has a cylindrical section  97  positioned between a first taper section  93 ′ and a second taper section  95 . In this embodiment, the locating pin  92  also has a base  99 , a base flange  101 , a flat top  107 , a shoulder  105  and a shoulder  103 . The first taper section  93 ′ is preferably tapered at an angle, α T1 , ranging from 30 to 70 degrees relative to the shoulder  103  of base  99 , and most preferably tapered at an angle of 45 degrees relative to the shoulder  103  of the base  99 . The second taper section  95 ′ is preferably tapered at an angle, α T2 , ranging from 50 to 85 degrees relative to the shoulder  103  of base  99 , and most preferably tapered at an angle of 75 degrees relative to the shoulder  103  of the base  99 . 
   Each locating pin  92 ′ has a length Lp preferably ranging from 1.5 inches to 4.0 inches, and most preferably a length of 2.3 inches. The base flange  101  has a length, “Lf”, preferably ranging from 0.025 inch to 0.500 inch, and most preferably from 0.175 inch to 0.200 inch. The base  99  has a length, “Lb”, preferably ranging from 0.75 inch to 2.0 inches, and most preferably a length of 1.25 inch. The second taper section  95 ′ has a length, “L T2 ”, preferably ranging from 0.250 inch to 0.750 inch, and more preferably from 0.550 inch to 0.650 inch. The cylindrical section  97  has a length, “Lc”, preferably ranging from 0.400 inch to 1.0 inch, and most preferably a length ranging from 0.600 inch to 0.850 inch. The first taper section  93 ′ has a length, “L T1 ”, preferably ranging from 0.080 inch to 0.150 inch, and most preferably from 0.100 inch to 0.130 inch. 
   As shown in  FIG. 7A , the base flange  101  has a radius, “R F ”, preferably ranging from 0.500 inch to 1.00 inch, and most preferably 0.75 inch to 0.90 inch. The base  99  has a radius, “R B ”, preferably ranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to 0.70 inch. The second taper section  95 ′ has a radius, “R T2 ”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. The second taper section  95  has a radius, “R T2 ”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. R T1  and R T2 , respectively, represent the largest radius of the first taper section  93 ′ and the second taper section  95 ′. The radius, if measured at other locations along each of the tapered section  93 ′ and  95 ′ will be smaller than R T1  and R T2 . 
   As shown in  FIGS. 8 and 8A , a bushing  94  has a first diameter, “D 1 ”, a second diameter, “D 2 ”, and a third diameter “D 3 .” The first diameter, D 1 , preferably has a diameter that ranges from 0.100 inch to 0.750 inch, and most preferably ranging from 0.350 inch to 0.500 inch. The second diameter, D 2 , preferably has a diameter that ranges from 1.0 inch to 1.750 inches, and most preferably ranging from 1.250 inches to 1.50 inches. The third diameter, D 3 , preferably has a diameter that ranges from 1.250 inches to 2.0 inches, and most preferably ranging from 1.50 inches to 1.750 inches. The bushing  94  preferably has a length Lbu, ranging from 1.0 inch to 2.0 inches, and most preferably from 1.25 inches to 1.50 inches. 
     FIG. 9  illustrates a preferred pair of mold inserts  30  that are used with the mold assembly  20  of the present invention. Each mold insert  30  preferably has a hemispherical cavity  32  within a body  34 . The body  34  preferably has an annular flange  36  that has an alignment flat  38  along a portion thereof. The flange  36  is preferably used for mounting each mold insert  30  within a mold half  22 . 
   The hemispherical cavity  32  preferably has an inverse dimple pattern thereon if a cover is formed on the golf ball precursor product  25  in the mold insert  30 . Alternatively, the hemispherical cavity  32  will have a smooth surface if a boundary layer is formed on the golf ball precursor product  25  in the mold insert  30 . Support pins  28  are preferably configured to support the golf ball precursor product  25  in a predetermined position within a mold cavity. Each mold half  22   a - b  includes a series of gates and a network of feeder lines, not shown, for carrying the injectable material into the cavities of each of the mold inserts  30  during the manufacturing process. 
   Preferred injectable materials include thermoplastic and reaction injection moldable materials. Preferred thermoplastic materials include ionomers and polyurethanes. Preferred reaction injection moldable materials include polyurethanes such as disclosed in U.S. Pat. No. 6,699,027, which pertinent parts are hereby incorporated by reference. 
     FIG. 10  illustrates the mold assembly  20  as utilized within an injection molding machine. The first mold half  22   a  is mounted to an upper frame  222  and the second mold half is mounted to a base  224 . A spring assembly  250  exerts pressure on the second mold half  22   a  during the de-molding process as explained below. The pressure exerted by the spring is adjusted by an adjuster  255 .  FIG. 111  is a top plan view of the second mold half  22   b  within the base  224 . The second mold half has a first end  300  and a second end  302 , and the spring assembly  250  exerts pressure on a first end  300  of the second mold half  22   b . In a preferred embodiment, the spring assembly exerts a pressure preferably ranging from 300 to 500 pounds per square inch. However, those skilled in the pertinent art will recognize that a greater or lesser pressure may be utilized without departing from the scope and spirit of the present invention. 
     FIGS. 12-14  illustrate the operation of the locating pins  92  during the de-molding process. In  FIG. 12 , the locating pin  92  is completely within a bushing  94 . The first taper section  93  within a first cavity  115  of the bushing  94 , the second taper section  95  within a second cavity  117  of the bushing  94  and a portion of the base  99  is within a third cavity  119  of the bushing  94 . 
   As shown in  FIG. 13 , the first mold half  22   a  further separates from the second mold half  22   b , preferably vertically. During the separation, the spring assembly  250  exerts a constant lateral pressure on the second mold half  22   b . As the locating pin  92  is separated from the bushing  94 , the first taper section  93  and second taper section  95  allow for a relatively smooth transition with the first taper section  93  moving from the first cavity  115  to the second cavity  117  and the second taper section  95  moving from the second cavity  117  to the third cavity  119 . During this separation, the second mold half  22   b  moves laterally in relation to the first mold half  22   a . In a preferred embodiment, the lateral distance moved by the second mold half  22   b  relative to the first mold  22   a  is the radius R 1 , which is half the diameter, D 1 , of the first cavity  115  of the bushing  94 . This preferred lateral movement a distance R 1  occurs during the separation, preferably vertical separation, a distance L T1 , the length of the first taper section  93 . The distance L T1 ) preferably corresponds to the depth of the first cavity  115 . 
   As shown in  FIG. 14 , the first mold half  22   a  further separates from the second mold half  22   b , preferably vertically. Again, during the separation, the spring assembly  250  exerts a constant lateral pressure on the second mold half  22   b . As the locating pin  92  is further separated from the bushing  94 , the first taper section  93  allows for a relatively smooth transition with the first taper section  93  now moving from the second cavity  117  to the third cavity  119 . During this separation, the second mold half  22   b  again moves laterally in relation to the first mold half  22   a . In a preferred embodiment, the lateral distance moved by the second mold half  22   b  relative to the first mold  22   a  is the radius R 2 , half the diameter, D 2 , of the second cavity  117  minus R 1 . This preferred lateral movement a distance R 2 -R 1  occurs during the separation, preferably vertical separation, a distance L T2 , the length of the second taper section  95 . The distance L T2  preferably corresponds to the depth of the second cavity  117 . 
   Although not shown, as the locating pin  92  completely separates from the bushing  94 , the second mold half  22   b  will laterally move due to the full extension of the spring assembly  255 . 
   The present invention allows for an easier separation of the mod halves  22   a - b  during de-molding and also allows for a separation of the newly molded golf ball or golf ball precursor product from a hemispherical cavity of each of the mold inserts  30 . 
   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.