Injection mold assembly

A method and assembly for molding golf balls is disclosed herein. The invention includes an injection mold assembly (20) with a first mold half (22a) having a plurality of cavities and at least one locating pin (92) and a second mold half (22b) 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 (22b). 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).

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.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS. 1-5, a mold assembly for injection molding a layer of a thermoplastic material on a golf ball precursor product is generally designated20, and is composed of a first mold half22aand a second mold half22b. In a preferred embodiment, the first mold half22ais the top mold half and the second mold half22bis the bottom mold half. The mold halves22a-bare mated together during the injection molding process.

Referring again toFIGS. 1-5, each mold half22a-bis generally composed of a solid body70. Each body70is preferably composed of a metal material, and most preferably composed of stainless steel. Each of the mold halves22a-bpreferably has a plurality of insert apertures33for preferably housing each of a plurality mold inserts30. Preferably, the insert apertures33each 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 insert30.

The first mold half22apreferably has a plurality of locating apertures74a-dat each corner. A plurality of locating pins92a-bare preferably mounted within two of the plurality of locating apertures74a-d. In a most preferred embodiment, locating pin92ais mounted within locating aperture74aand locating pin92bis mounted within locating aperture74d.

The second mold half22bpreferably has a plurality of locating apertures74f-hat each corner. A plurality of locating bushings94a-bare preferably mounted within two of the plurality of locating apertures74f-h. In a most preferred embodiment, locating bushing94ais mounted within locating aperture74gand locating bushing94bis mounted within locating aperture74f.

The locating pins92a-band locating bushings94a-bproperly align the mold halves22a-bduring mating thereof to form the mold assembly20. In a preferred embodiment, each of the plurality of locating pins92a-bis diagonally opposed to each other on the first mold half22a, and each of the plurality of locator bushings94a-bis diagonally opposed to each other on the second mold half22b.

As shown inFIGS. 6,6A and6B, a preferred embodiment of the locating pin92has a first taper93section, a second taper section95, a base99and a base flange101. The locating pin92preferably has a flat top107. The base flange101has a shoulder105to lock the locating pin within an aperture74. The base99has a shoulder103. The first taper section93is preferably tapered at an angle, αT1, ranging from 30 to 70 degrees relative to the shoulder103of base99, and most preferably tapered at an angle of 45 degrees relative to the shoulder103of the base99. The second taper section95is preferably tapered at an angle, αT2, ranging from 50 to 85 degrees relative to the shoulder103of base99, and most preferably tapered at an angle of 75 degrees relative to the shoulder103of the base99.

Each locating pin92has a length Lp preferably ranging from 1.5 inches to 4.0 inches, and most preferably a length of 2.3 inches. The base flange101has 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 base99has 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 section95has a length, “LT2”, preferably ranging from 0.100 inch to 0.500 inch, and more preferably from 0.200 inch to 0.300 inch. The first taper section93has a length, “LT1”, preferably ranging from 0.250 inch to 1.00 inch, and most preferably from 0.500 inch to 0.750 inch.

As shown inFIG. 6A, the base flange101has a radius, “RF”, preferably ranging from 0.500 inch to 1.00 inch, and most preferably 0.75 inch to 0.90 inch. The base99has a radius, “RB”, preferably ranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to 0.70 inch. The second taper section95has a radius, “RT2”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. The second taper section95has a radius, “RT2”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. RT1and RT2, respectively, represent the largest radius of the first taper section93and the second taper section95. The radius, if measured at other locations along each of the tapered section93and95will be smaller than RT1and RT2.

In an alternative embodiment shown inFIGS. 7,7A and7B, the locating pin92′ has a cylindrical section97positioned between a first taper section93′ and a second taper section95. In this embodiment, the locating pin92also has a base99, a base flange101, a flat top107, a shoulder105and a shoulder103. The first taper section93′ is preferably tapered at an angle, αT1, ranging from 30 to 70 degrees relative to the shoulder103of base99, and most preferably tapered at an angle of 45 degrees relative to the shoulder103of the base99. The second taper section95′ is preferably tapered at an angle, αT2, ranging from 50 to 85 degrees relative to the shoulder103of base99, and most preferably tapered at an angle of 75 degrees relative to the shoulder103of the base99.

Each locating pin92′ 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 flange101has 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 base99has 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 section95′ has a length, “LT2”, preferably ranging from 0.250 inch to 0.750 inch, and more preferably from 0.550 inch to 0.650 inch. The cylindrical section97has 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 section93′ has a length, “LT1”, preferably ranging from 0.080 inch to 0.150 inch, and most preferably from 0.100 inch to 0.130 inch.

As shown inFIG. 7A, the base flange101has a radius, “RF”, preferably ranging from 0.500 inch to 1.00 inch, and most preferably 0.75 inch to 0.90 inch. The base99has a radius, “RB”, preferably ranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to 0.70 inch. The second taper section95′ has a radius, “RT2”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. The second taper section95has a radius, “RT2”, preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35 inch to 0.50 inch. RT1and RT2, respectively, represent the largest radius of the first taper section93′ and the second taper section95′. The radius, if measured at other locations along each of the tapered section93′ and95′ will be smaller than RT1and RT2.

As shown inFIGS. 8 and 8A, a bushing94has a first diameter, “D1”, a second diameter, “D2”, and a third diameter “D3.” The first diameter, D1, 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, D2, 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, D3, 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 bushing94preferably 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. 9illustrates a preferred pair of mold inserts30that are used with the mold assembly20of the present invention. Each mold insert30preferably has a hemispherical cavity32within a body34. The body34preferably has an annular flange36that has an alignment flat38along a portion thereof. The flange36is preferably used for mounting each mold insert30within a mold half22.

The hemispherical cavity32preferably has an inverse dimple pattern thereon if a cover is formed on the golf ball precursor product25in the mold insert30. Alternatively, the hemispherical cavity32will have a smooth surface if a boundary layer is formed on the golf ball precursor product25in the mold insert30. Support pins28are preferably configured to support the golf ball precursor product25in a predetermined position within a mold cavity. Each mold half22a-bincludes 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 inserts30during 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. 10illustrates the mold assembly20as utilized within an injection molding machine. The first mold half22ais mounted to an upper frame222and the second mold half is mounted to a base224. A spring assembly250exerts pressure on the second mold half22aduring the de-molding process as explained below. The pressure exerted by the spring is adjusted by an adjuster255.FIG. 111is a top plan view of the second mold half22bwithin the base224. The second mold half has a first end300and a second end302, and the spring assembly250exerts pressure on a first end300of the second mold half22b. 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. 12-14illustrate the operation of the locating pins92during the de-molding process. InFIG. 12, the locating pin92is completely within a bushing94. The first taper section93within a first cavity115of the bushing94, the second taper section95within a second cavity117of the bushing94and a portion of the base99is within a third cavity119of the bushing94.

As shown inFIG. 13, the first mold half22afurther separates from the second mold half22b, preferably vertically. During the separation, the spring assembly250exerts a constant lateral pressure on the second mold half22b. As the locating pin92is separated from the bushing94, the first taper section93and second taper section95allow for a relatively smooth transition with the first taper section93moving from the first cavity115to the second cavity117and the second taper section95moving from the second cavity117to the third cavity119. During this separation, the second mold half22bmoves laterally in relation to the first mold half22a. In a preferred embodiment, the lateral distance moved by the second mold half22brelative to the first mold22ais the radius R1, which is half the diameter, D1, of the first cavity115of the bushing94. This preferred lateral movement a distance R1occurs during the separation, preferably vertical separation, a distance LT1, the length of the first taper section93. The distance LT1) preferably corresponds to the depth of the first cavity115.

As shown inFIG. 14, the first mold half22afurther separates from the second mold half22b, preferably vertically. Again, during the separation, the spring assembly250exerts a constant lateral pressure on the second mold half22b. As the locating pin92is further separated from the bushing94, the first taper section93allows for a relatively smooth transition with the first taper section93now moving from the second cavity117to the third cavity119. During this separation, the second mold half22bagain moves laterally in relation to the first mold half22a. In a preferred embodiment, the lateral distance moved by the second mold half22brelative to the first mold22ais the radius R2, half the diameter, D2, of the second cavity117minus R1. This preferred lateral movement a distance R2-R1occurs during the separation, preferably vertical separation, a distance LT2, the length of the second taper section95. The distance LT2preferably corresponds to the depth of the second cavity117.

Although not shown, as the locating pin92completely separates from the bushing94, the second mold half22bwill laterally move due to the full extension of the spring assembly255.

The present invention allows for an easier separation of the mod halves22a-bduring 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 inserts30.