Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/0025—Preventing defects on the moulded article, e.g. weld lines, shrinkage marks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
  • B23P15/24—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass dies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/76—Cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/03—Injection moulding apparatus
  • B29C45/04—Injection moulding apparatus using movable moulds or mould halves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
  • B29C45/14065—Positioning or centering articles in the mould
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
  • B29C45/14819—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles the inserts being completely encapsulated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2905/00—Use of metals, their alloys or their compounds, as mould material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/54—Balls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/54—Balls
  • B29L2031/546—Golf balls
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining
  • Y10T29/49885—Assembling or joining with coating before or during assembling

Definitions

• the embodiments described herein relate generally to the manufacture of golf balls, and specifically to a cavity mold assembly for injection molding a golf ball cover on a golf ball, using a layer of insulating material between the metal cavity mold halves and the injection molded material to slow the freezing of the injected material and thus enable a thin cover or a low-flow material cover to be molded before "material freeze-off occurs.
• golf ball injection molding cavities are made of metal, which is a good conductor of heat. It is difficult to injection mold very thin covers on golf balls using materials such as thermoplastics or thermoplastic elastomers because a point is reached where the heat removal from the injected material by the metal mold is such that the melted material can not fill the mold before "material freezing off occurs. Even with relatively thick covers, the use of a very low flow material can also have problems with "material freezing off before the mold can be completely filled.
• an injection molding cavity for molding a thin or a low-flow material cover or mantle layer for a golf ball.
• the injection molding cavity forms a cavity for defining a golf ball cover or mantle layer, the golf ball layer comprising a thickness that corresponds to a space defined by the cavity; a metal surface layer surrounding the cavity; and an insulating layer surrounding the metal surface layer.
• the thickness of the insulating layer is selected based on the thickness of the metal layer, which in turn depends on the desired golf ball layer thickness. For a thinner golf ball layer, the metal surface layer is made thinner, and the insulating layer is made thicker to reduce heat loss through the metal layer.
• an injection molding cavity for molding a thin or low flow material layer for a golf ball comprises a cavity for defining an outer surface of a golf ball layer, a metal surface surrounding the cavity, the metal surface comprising a thickness, and an insulating layer at least partially surrounding the metal surface, the insulating layer comprising a plurality of regions located in certain areas relative to the metal surface.
• an injection molding cavity assembly for molding a thin layer or a low- flow material layer on a golf ball core comprises a cavity for defining a golf ball layer, the golf ball layer comprising a thickness that corresponds to a space defined by the cavity; an insulating layer surrounding the cavity, the insulating layer comprising a thickness; and a metal cavity mold assembly surrounding the insulating layer, the insulating layer having a heat conduction coefficient that is less than a heat conduction coefficient of the metal cavity assembly.
• the golf ball core may be a generally spherical, unitary body of one material, such as rubber, plastic, or the like, or may itself have multiple layers, such as one or more mantle layers or a multi-piece rubber or plastic core.
• the core may be non-spherical in areas.
• the injection mold cavity assembly may be designed to define a spherical cavity or a cavity which is non-spherical, depending on the desired shape of the golf ball layer being formed. In one embodiment, each half cavity is of hemispherical or substantially hemispherical shape, where the layer of the golf ball is intended to be of uniform thickness.
• different insulated cavity assemblies may be provided to form multi-layer balls, with a first assembly for forming a mantle layer and a second assembly for forming an outer cover over the mantle layer, for example.
• the half cavities of one cavity assembly may be designed to form a non-spherical cavity for forming a mantle layer (or a cover layer) which is not completely spherical and which is thinner in some regions and thicker in other regions.
• FIG. 1 is a cross-sectional diagram illustrating a conventional golf ball injection mold cavity assembly
• FIG. 2 is a flow chart illustrating an example method for constructing a golf ball injection mold cavity in accordance with one embodiment
• FIGS. 3-9 are cross-sectional diagrams illustrating examples of golf ball injection mold cavity assemblies configured in accordance with various embodiments
• FIG. 10 is a side perspective view of the metal molding surface or half shell used in one mold half of another embodiment of an insulated injection mold cavity assembly
• FIG. 11 is a bottom perspective view illustrating the lower surface of the metal molding layer illustrated in FIG. 10;
• FIG. 12 is a vertical cross-sectional view through a metal part used in forming the metal molding layer or half shell of FIGS. 10 and 1 1 after cutting of dimples into the outer or undersurface of the molding layer and prior to cutting the dimple pattern into the injection molding surface or inner surface of the molding layer;
• FIG. 13 is a top perspective view of the base of the mold half for receiving the half shell of FIGS. 10 to 12;
• FIG. 14 is a cross sectional view through the mold base of FIG.
• FIG. 15 is a cross sectional view similar to FIG. 14 but illustrating the metal half shell molding layer of FIGS. 10 to 12 being lowered into position in the base;
• FIG. 16 is a cross-sectional view illustrating the metal half shell positioned with the hemispherical shell portion engaged in the hemispherical cavity in the base;
• FIGS. 17A to 17D are cross-sectional views illustrating alternative constructions for the core pin and vent pin and the core pin and vent pin receiving bore in one mold half of the injection mold assembly;
• FIG. 18 is a cross-sectional view illustrating one embodiment of a mold half assembled from the parts of FIGS. 10 to 15 and forming one half of an injection mold cavity assembly for molding a golf ball cover layer.
• Certain embodiments as disclosed herein provide for an insulated mold cavity assembly for forming a layer on a golf ball core.
• the layer may be an inner or mantle layer or a cover or outer layer of a golf ball.
• core refers to any partially formed golf ball on which one or more additional layers are to be formed, such as a one piece or unitary core of rubber, plastic or the like, a multi-piece core, or a core comprising a center part or middle on which one or more mantle layers are already formed.
• layer means any layer between the center of a golf ball and the final outer surface of the golf ball, such as the outer cover layer or any intervening mantle or inner layer between the center and outer surface.
• spherical refers to a completely or substantially spherical or hemispherical surface or layer, and includes a spherical layer with surface patterns of dimples, tubular lattice formations, inverse dimples, or the like as are commonly found on golf balls.
• FIG. 1 is a diagram illustrating a conventional golf ball injection mold assembly comprising top mold half 200 and bottom mold half 100 having opposing faces which each have a hemispherical recess, the recesses together defining a mold cavity 300 in which golf ball core 400 is suspended, so as to allow a cover or a mantle layer to be molded in the remainder of the cavity between the ball and top and bottom mold halves.
• the spherical injecting molding metal surface 101, 201 for forming the outer surface of a golf ball cover layer is shaped to form the desired dimple pattern. As illustrated, the hemispherical cavities have projections or bumps to form the desired golf ball dimple pattern.
• Golf ball core 400 is suspended in the center of cavity 300 via pins 203 and 103 on top and bottom respectively.
• Top and bottom vent pins, 204 and 104 respectively, are included to allow for gases from cavity 300 to be evacuated during molding.
• One or more material injection ports or gates 301 formed by recesses in the opposing faces of the mold halves allow the cover material to be injected into the gap between core 400 and the molding surfaces 101 and 201.
• the cavity temperature is usually below the freezing point of the injected material at the time when the material injection begins.
• the injected material is usually injected between the spherical core 400, or mantled core, suspended in the center of the cavity 300 and the metal wall 101 and 201 of the injection molding cavity. Heat is drawn from the material by both the metal cavity wall 101 and 201 and the suspended core 400. Since the outside of the suspended core 400 is usually a rather low heat conducting material like rubber or plastic, the heat removal rate from the injected material to the core 400 is usually not nearly as fast as the heat removal rate to the surface 101 and 201 of the metal injection molding cavity.
• the rate of heat removal from the injected material can be fast enough that the material solidifies before it has a chance to fill the entire cavity space 300 between the metal wall 101 and 201 and the suspended core 400.
• the cover or mantle layer does not fully encase the golf ball core 400 and the resulting part is considered defective.
• the embodiments described herein use a layer of insulating material between the metal mold halves surrounding the cavity and the injection molded material to slow the freezing rate of the injected material and thus enable a thin layer or a low-flow material to be molded around a golf ball core before "material freeze-off occurs.
• the mold surfaces 101, 201 of the mold halves 100, 200 of FIG. 1 are replaced by molding surfaces or layers 205, 206 of insulating material.
• the metal molding surfaces 101, 201 of FIG. 1 are replaced by relatively thin metal molding layers or half shells 112, 212, respectively, which form the mold surface in cavity 300, and layers 102, 202 of insulating material between each metal layer 112, 212 and the respective metal mold half.
• insulation layer e.g., layer 205 and
• the materials and dimensions of the insulating layer 205,206 of FIG. 3 and the combined dimensions of the insulating layer 102, 202 and metal layer 112, 212 of FIG. 4 should be such that it allows the molten plastic material to sufficiently fill the cavity space 300 between the core 400 and surrounding molding surface.
• the thickness of the two layers 102, 112 and 202, 212 on each side of the mold cavity depends on the desired cover layer thickness or volume.
• the metal molding surface layer 112, 212 is made thinner so that it absorbs less heat itself, and the insulating layer, e.g., layer 102, 202, is made thicker, since more insulation is desirable when injection molding a thinner cover layer, where material freeze off is a greater concern.
• the thickness of the insulating layer increases as the thickness of the metal surface layer defining the outer surface of the mold half cavity decreases.
• the insulating layer can be any material that has a heat conduction coefficient that is less than the heat conduction coefficient of the metal molding surface, or than the metal cavity assembly. It can be a metal, plastic, ceramic, glass, liquid or gaseous material or any other type of material or combination of materials as long as it acts as an insulating layer compared to the metal molding surface or the metal cavity assembly.
• FIG. 2 is a flow chart illustrating an example process for constructing an insulated injection molding cavity that could be used to form the thin cover layer of a golf ball or could be used to injection mold materials with low melt flow characteristics.
• the following description refers to molding of the outer cover layer of a golf ball, the same process may also be used to mold mantle layers onto the golf ball core.
• step 220 for each half of the mold cavity, a block of metal is machined into the approximate dimensions of the bulk of the cavity assembly.
• each block is cut out to form the desired mold half shape, with the face of the block which opposes the other mold half cut to form the desired hemispherical recess 114, 214, with the dimensions selected such that the recess is larger than the desired cover layer thickness by an amount equal to the selected combined thickness of layers 102,112 or 202, 212.
• pilot holes can be drilled in the mold halves for receiving the vent pins 104, 204. These holes on each mold half will be the point at which the excess insulation material escapes for the case of a polymer insulation material such as an epoxy resin. Pilot holes are also drilled for receiving the core pins 103, 203 which support the golf ball core 400 in the center of the cavity.
• Core 400 may be a single part core or a multi-piece rubber or plastic core, or may be composed of several layers, such as a central core and one or more mantle layers.
• a metal half shell or layer is formed for the inner or opposing face of each mold half in the shape of a hemisphere with a peripheral rim.
• the metal layer in one embodiment is approximately 0.03-0.3" thick and has an outside diameter such that it fits into the cavity 114, 214 with the rim extending over the rim of the cavity in the respective mold half, and allows the proper space for the insulation material to be formed between the mold half and the metal layer or half shell.
• the thickness of the metal half shell or layer may be less than 0.03 inches, as described below in connection with FIGS. 10 to 18.
• the shape may be non-hemispherical in some embodiments, where a layer is to be formed which is not completely spherical, i.e. thicker in some regions and thinner in others.
• the metal shell may be made thicker in some regions, such as around the rim, so as to better withstand the forces during the process of adhering the shell in the mold cavity, as described below in connection with step 230, or may be supported on its outer surface during the adhering process so that it does not deform, particularly where the metal layer is very thin.
• the insulation material can be added to extend over the hemispherical cavity and outer rim of the recessed faces of the two mold halves.
• a sufficient amount of a liquid pre -polymer plastic material can be coated over the respective mold half faces, such as a 2-part epoxy.
• step 230 the half shell or metal layer 112 and 114 are pressed onto the respective mold half faces until the hemispherical portion registers into place with the hemispherical cavity in the respective mold face, with a gap between the opposing faces of the metal layer and mold half.
• the polymer material can be allowed to cure in place, and excess polymer material can be trimmed off.
• the insulating material acts as the adhesive that permanently bonds the half shell to the cavity assembly.
• an adhesive can be added to permanently bond the half shell to the cavity assembly.
• the thickness of the insulating layer may be 0.25 inches or less, and in one embodiment the insulating layer has a thickness in the range from 0.002 to 0.08 inches.
• the insulating material can comprise a plurality of regions located in specific areas relative to the cavity. In such embodiments, additional steps to pattern or remove the insulating material will also be performed.
• step 234 e.g., a 5 axis CNC machining device can be used to cut the inverse of the golf ball dimple pattern onto the outer surface of the metal half shell or layer, i.e. the mold surface.
• step 2366 the other components of the assembly can be machined into the cavity assembly including: vent pins, gates, core pins, etc.
• the half shells or metal layers can also have the inverse dimple pattern formed on them before the half shells are inserted into the cavity assembly.
• FIGS. 3 to 18 are diagrams illustrating examples of golf ball injection molded cavities configured in accordance with various embodiments.
• the metal mold surface 101 and 201 has been replaced with an insulating material layer 205 and 206.
• the insulating layer 102 and 202 is located directly below the metal half shell or layer 112, 212, i.e. between the surface of the metal mold half 100, 200 and the metal half shells or layers 112, 212, respectively.
• the insulating layer 102, 202 is of increasing thickness from the edge to the center of the respective hemispherical cavity in FIG. 4, it may be of uniform thickness in alternative embodiments.
• each insulating layer 102, 202 has a portion 118, 218 which extends under at least part of the injection gate regions at the injection ports 301.
• the rim of the respective half shells or metal layers 112, 212 may be undercut to receive the extended portions 118, 218 of the insulating layer. In the embodiment of FIG. 5, however, the insulation layer 102, 202 does not extend under the injection gate regions at the rims of the respective half shells 112, 212.
• the embodiment of FIG. 5 is otherwise identical to that of FIG. 4 and like reference numbers are used for like parts as appropriate.
• the insulated area could be only that portion that is in the bottom half 100 of the mold, which is the area that is last filled with plastic, or only in the top half 200 of the mold, or in the area around the equator region where the injection gates introduce the plastic material into the cavity.
• the insulated layer between each metal layer 112, 212 forming the cavity and the underlying recess in the metal mold half is broken up and consists of regions 120, 220 of insulated material that reside in some places directly below the metal molding surface or half shell 112, 212, but not below the injection gate regions.
• the mold half 100 and 200 can include projections (not shown) in the areas where the insulation material contacts the molding surface, which can act as a point of registration and/or alignment for the molding surface.
• insulation material are provided in the polar region of each half of cavity 300 between metal layers 112, 212 and the underlying surface of the mold half. This can have the effect of keeping the polar regions warmer for a longer period of time and thus helping prevent the cold welds and molding imperfections like "crow's feet" from appearing near the vent pins.
• regions or portions 122, 222 of insulation material which are spaced from the pins are provided in the polar region of each half of cavity 300, as in FIG. 8, and additional insulation regions 124, 224 are also provided below the rim 115, 215 of each half shell or metal layer 112, 212 in the injection gate areas 301.
• the insulation around the core and vent pins 103 and 203 and 104 and 204 respectively has been removed so that the pins are enclosed in metal. Having insulation material near the injection gates will help prevent polymer heat loss in this area while at the same time allowing the adjacent un-insulated gates and equator region to solidify fairly quickly, preventing excess polymer flash.
• FIGS. 10 to 18 illustrate one mold cavity half 500 of another embodiment of an injection mold cavity assembly in more detail, as well as various stages of construction of the mold cavity half.
• the mold cavity in this embodiment is similar to that of FIG. 4, and basically comprises a metal mold cavity base 510, a metal dimpled layer 512 secured over the recessed surface of the base, and an insulating layer 513 of epoxy material or the like between the metal layer 512 and the base 510.
• FIGS. 10 to 15 illustrate the metal mold half base 510 and metal half shell or metal injection molding surface layer 512 of mold half 500 at various stages in construction of the mold half
• FIGS. 17A to 17D illustrate some alternative arrangements for the vent and core pin receiving bores
• FIG. 16 and 18 illustrate the fully assembled mold half 500.
• FIGS. 10 to 18 is similar to that of FIG. 4, with a continuous insulating layer 513 between the hemispherical regions of the base and metal half shell or layer, and extending part of the way along each gate forming region 514 of the metal shell between the base and metal layer 512.
• FIGS. 10 and 11 illustrate the thin metal dimpled layer or half shell 512 which forms one half of the molding surface surrounding the mold cavity (e.g. cavity 300 in FIG. 4), while FIGS. 13 and 14 illustrate the metal mold cavity half or base 510 in which the metal layer or shell is engaged.
• each mold cavity half or base 510 comprises a generally cylindrical body having a hemispherical cavity 505 cut in one face 509 which opposes the other mold cavity half in the assembled mold cavity, and core and vent pin bores or holes 508 drilled at selected locations between the opposite face 511 of base 510 and the cavity 505.
• the position of the core and vent bores 508 in the base of hemispherical cavity 505 in one embodiment is illustrated in FIG. 13, although a greater or lesser number at the same or different positions may be provided in alternative embodiments.
• the rim 506 of the base surrounding cavity 505 has a plurality of generally radial grooves 515 comprising epoxy insulation flow channels, and circumferentially extending overflow channels 516 extending between the radial grooves. Cavity alignment pin holes 518 may also be provided in rim 506. Support and centering features or ledges 520 may be provided adjacent the edge of cavity 505 for locating and centering the dimpled metal layer or shell 512 which is described in more detail below.
• Base 510 has outer annular channels or grooves 522 for receiving O-ring seals and a central large water cooling channel 524, as illustrated in FIG. 10. These channels are omitted for convenience in FIGS. 13 to 16.
• cavity 505 is cut in the face of base 510 with appropriate dimensions to accommodate the metal molding layer 512 with 5-10 mil of epoxy insulation between them. This part is cut from a material that has good strength, corrosion resistance and has lower conductivity and/or lower heat capacity than stainless steel, such as a titanium alloy or metal with similar properties. In one example, the titanium alloy Ti-6%A1-4%V was used for base 510.
• the metal molding layer or half shell 512 which provides half of the hemispherical molding surface for the outer cover of a golf ball may be of stainless steel or other materials. It may be of titanium or titanium alloy material such as the material described above for the base 510. Any low conductivity metal may be used for molding layer 512.
• a metal material for the molding surface is that the product of the specific gravity and specific heat of the material should be low. It is also important that the material's thermal conductivity is low.
• Ti-6%Al-2% Sn- 4%Zr-2% Mo is another titanium alloy that may be used for molding layer 512. This material has low thermal conductivity, low specific gravity and a relatively low specific heat. Other materials with similarly low thermal conductivity, low specific gravity and relatively low specific heat may alternatively be used.
• the metal molding layer or half shell 512 is shaped to form a hemispherical portion 580 surrounded by a peripheral rim 582.
• the shell 512 has opposite outer and inner surfaces 525 and 526, with the hemispherical portion of the inner surface 526 forming half of the spherical molding surface of the mold assembly, and the outer surface or underside 525 of the shell facing the insulating layer 513 when the mold half is fully assembled, as in FIG. 18.
• the hemispherical portion 580 is formed with a series of raised bumps or protuberances 542 on inner surface 526 and matching indentations 544 on outer surface 525, with the shape and dimension of the protuberances being selected based on the desired golf ball dimple pattern.
• the undersurface 525 also includes projections or bosses 532 around the center of the hemispherical portion 580 which are designed to extend into the bores 508 in the metal base, as described in more detail below, and which also act as registration points when lowering the shell 512 into the base 510.
• the peripheral rim 582 of shell 512 is shaped to form half gates 514 which define the injection molding ports 301 when two identical half cavity molds 500 are secured together in face-to-face engagement to form the mold cavity 300.
• the undersurface of rim 582 has indentations forming flow rings or recesses 535 for receiving insulation material under the rim.
• the rim also has alignment pin holes 534 (FIG. 11) for alignment with the corresponding holes 518 in base 510 when the parts are assembled
• the metal molding layer 512 may be cut from a suitably sized block of material.
• the block may be undercut from the bottom side to form the hemispherical portion 580 of underside or outer surface 525 of the mold cavity, surrounded by peripheral rim 582 which is seated on the rim 506 of base 510.
• surface 525 is cut to match the desired surface pattern of the golf ball layer to be molded, while inner or molding surface 526 is subsequently cut to form the inverse of the desired golf ball layer surface.
• the pattern is a dimple pattern, and indents or dimples 544 are cut in the hemispherical portion of the surface using the desired dimple design.
• different surface patterns or no surface patterns at all may be formed in the half shells or metal layers, depending on the desired surface configuration of the golf ball layer.
• the half shells may be configured with any desired surface configuration to form the selected golf ball surface pattern.
• the layer to be formed is an inner or mantle layer, no outer surface pattern is needed and the half shell cavity portions are formed with no surface pattern.
• the dimple design may comprise dimples of the same diameter and depth or of different diameters and depths, and may include spherical or non spherical dimples as well as truncated dimples, or other dimple shapes, with the dimple configuration including dimples of different shapes or dimples which are of the same shapes, with the number of dimples and dimple shapes and dimensions depending on the desired golf ball surface configuration.
• the cavity portion of the shell in other embodiments may be designed to form other golf ball surface configurations, rather than indented dimples, for example tubular lattice structures, raised bumps, a mixture of indented dimples and bumps, or other surface features and shapes as desired to produce various golf ball surface designs.
• half shells may also be formed with smooth hemispherical or non-hemispherical surfaces having no bumps or indentations, for example where the insulated cavity is to be used to form an interior or mantle layer of a golf ball.
• shells with curved but non- spherical cavity portions may be used to form a non-spherical mantle layer which is thinner and thicker in different regions, for example.
• the block in the illustrated embodiment is cut to include projections 532 from surface 525 for the core and vent pins 508. These projections also act as registration points since they engage the bores 508 formed in the base of the injection molding half or cavity.
• Rim 582 includes alignment openings 534 for cavity alignment pins to align molding layer 512 with the cavity 505 in base 510 when the parts are assembled.
• the rim 582 is also undercut to form flow rings or recesses 535 for the material forming insulating layer 513, as well as to form the lower surfaces of the injection molding gates or ports 514.
• the metal layer forming the dimpled cavity is made thicker in a region 545 around the top of the cavity (see FIGS. 10 and 18) to provide extra strength around the edge.
• FIG. 12 is a cross sectional view of the block 560 of metal used to form the shell after the undersurface 525 of the metal molding layer has been cut, and after formation of the injection molding inlets or gates 514 in inner surface 526 of the rim but prior to cutting away material from face 540 to form the hemispherical inner metal molding surface which provides half of the injection molding surface for the outer surface of the golf ball cover layer.
• the two parts (base and metal molding layer or shell, or partially formed shell as in FIG. 12) are glued together with an adhesive insulating material that can tolerate the high temperatures of injection molding, such as an epoxy material.
• an adhesive insulating material that can tolerate the high temperatures of injection molding, such as an epoxy material.
• a sufficient amount of a liquid pre-polymer plastic material, such as two part epoxy is applied to the exposed cavity and rim of the base 510 (i.e. the upper surface as seen in FIGS. 13 and 14) to form a coating 513 as illustrated in FIG. 15, and the metal molding layer is placed over the indented surface of the base and lowered so that the hemispherical portion enters cavity 505.
• the metal molding layer 512 is registered with the cavity 505, with projections 532 engaging in the corresponding bores 508 in the base and the undersurface of rim 582 opposing the rim 506 of the base, the polymer or epoxy material 513 filling the gap between the parts is allowed to cure in place, with any excess material flowing out through overflow channels 515.
• the insulating material acts as the adhesive that permanently bonds the metal molding layer 512 to the base 510 of the cavity half, as illustrated in FIG. 18.
• the part which forms the metal molding layer 512 is machined down from face 540 of FIG. 12 to form the inner or cavity forming face 526 of the shell, with the desired inverse dimples or bumps 542 and other features on face 526 of the metal molding layer, as well as bores through the projections 532 for receiving core and vent pins 546 inserted through bores 508 in the base 510, as illustrated in FIG. 18. Because the cavity parts are very accurately aligned with each other, the inverse dimple features or bumps 542 formed on the exposed face or cavity molding surface 526 of layer 512 are aligned with the dimple features 544 on the underside or face 525 of the metal layer.
• the metal molding surface of substantially uniform thickness in all areas.
• the careful alignment also allows the metal molding surface to be cut to a thickness as thin as 0.003- 0.007". By making the surface this thin, the heat capacity of the metal molding surface is reduced substantially and thus it draws a smaller amount of heat from the molten plastic, so a thin cover layer on a golf ball may be molded without freeze-off occurring before the part is completed.
• the insulated area between the metal base and shell of mold half 500 has been expanded to include the portions forming the injection gates 514.
• the metal available for heat conduction is reduced or minimized in the metal surface layer or shell 512 surrounding the cavity as well as the regions around the injection gates 514.
• the holes 508 in each mold base 510 includes five smaller holes for receiving vent pins and four larger holes for receiving core pins.
• FIGS. 17A to 17D illustrate four different alternative configurations for the area around the core and vent pins 103, 104 or 203, 204, with FIG. 17C corresponding to the configuration in the embodiment of FIGS. 10 to 16 and 18. All other parts of the injection molding cavity assembly are the same as in the embodiment of FIG. 4 or FIGS. 10 to 16 and 18, and like reference numbers have been used for like parts as appropriate.
• FIG. 17A The configuration of FIG. 17A is possibly the easiest for construction purposes because the metal molding surface or layer 512A is adhered to the bottom part of the cavity 505 and core pin or vent pin holes 508A are simply drilled through the cavity assembly after the epoxy or other insulation material 513A has hardened.
• the potential problem with this design is the pins 103, 104 and 203, 204 in each half of the cavity assembly are moving up and down against the thin molding surface and this area can fatigue or wear away.
• projections 570 are formed in the surface of base cavity 505 around each hole 508B and enlarged holes 572 in the metal molding layer 512B engage over the projections.
• Bores 508B for receiving the core and vent pins extend only through the metal of base 510B, and the epoxy or insulating layer 513B extends into the gap between each projection 570 and the surrounding hole 572.
• the exposed epoxy 574 in the mold surface 526B could cause problems due to plastic adhesion to the epoxy.
• the design also requires more work in preparing the cavity base and molding surface so that they properly mate when placed together. A positive feature is that each pin is only in contact with metal.
• FIG. 17C illustrates the arrangement described above in connection with FIGS. 10 to 16, in which projections 532 are formed in the undersurface 525 of the metal half shell or mold surface layer 512C, and engage in enlarged portions 558 at the upper ends of bores 508 in the base.
• the epoxy layer 513C extends into the space 575 between the projections 532 and enlarged portions 558, and excess epoxy is removed from the tight tolerance area. This is probably the easiest configuration for manufacturing purposes.
• FIG. 17 D illustrates another alternative which presents fewer issues than FIGS. 17A and 17B with respect to metal-epoxy surface contact in tight tolerance locations.
• the metal half shell or molding surface layer 512D is formed with projections 576 extending from the undersurface of layer 512D through the entire length of the enlarged bores 508D in the base, with a gap between projections 576 and bores 508D which is filled with epoxy material 578.
• core and vent pin bores 580 extend through the metal shell layer only, and epoxy material is removed from the core and pin areas entirely.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=43823367

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (17)

Family Cites Families (21)

• 2010
  • 2010-10-04 KR KR1020127011585A patent/KR20120096482A/ko not_active Withdrawn
  • 2010-10-04 CN CN2010800552007A patent/CN102639306A/zh active Pending
  • 2010-10-04 AU AU2010303656A patent/AU2010303656A1/en not_active Abandoned
  • 2010-10-04 WO PCT/US2010/051366 patent/WO2011044059A2/en not_active Ceased
  • 2010-10-04 US US12/897,669 patent/US8882490B2/en not_active Expired - Fee Related
  • 2010-10-04 JP JP2012533237A patent/JP2013506585A/ja active Pending
• 2014
  • 2014-07-07 US US14/325,163 patent/US20140322384A1/en not_active Abandoned

Also Published As

Similar Documents

Legal Events