US 3364607 A
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1958 G. H. TWICKLER 3,36
BOW L I N G B A LL ATTORNEYS United States Patent OfiFice 3,364,697 Patented Jan. 23, 1968 3,364,607 BGWLING BALL George Herman Twickler, Needham, Mass, assignor to Stow -Woodward, 1112., Newton Upper Falls, Mass. Filed Oct. 20, 1964, Ser. No. 405,184 1 Claim. (61. 40-327) This invention relates to novel and improved bowling ball structures and methods of manufacture.
Bowling balls of the type embodying the present invention generally comprise a spherical outer shell or veneer formed of a relatively heavy, wear and impact resistant material, usually a natural or synthetic polymer; and an inner core enclosed within the veneer and in turn, comprising an outer shell of a relatively heavy impact resistant material bonded around a relatively light insert formed, for example, of a solid cellular material. It is often desirable for a number of reasons to inlay the veneer with a member in the form of or bearing some distinctive design, character or indicia. Due to the severe impact stresses to which a bowling ball is frequently subjected, inlay members tend to loosen from the material (of the veneer) in which they are embedded and become dislodged.
Objects of the invention are: to provide a bowling ball of the type described including a novel inlay member and having a mechanical structure with improved reliability in which the inlet member is embedded and retained within the veneer so as to be secure against loosening and dislodgement; and to provide an improved method of fabricating and assembling the ball and insert to produce an integral structure assured of remaining intact despite the repeated impact stresses to which bowling balls are subjected.
Other objects of the invention are: to provide a bowling ball structure as described in which the inlay member includes an anchor portion tapered toward the exterior of the ball and embedded within the veneer and a flange on its interior end engaged between the veneer and core; and to provide a method of manufacture in which the inlay member, veneer and core are formed separately of polymerizable materials, the inlay member is partially polymerized, the inlay member, veneer and care are pressed together and the inlay member, veneer and core are polymerized.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the product possessing the features, properties and the relation of components and the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claim.
F or a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:
FIG. 1 is a fragmentary sectional view of a portion of a bowling ball embodying the invention;
FIGS. 2 and 3 are perspective views of inlay members;
FIG. 4 is a view, partially in section, illustrating a method of manufacturing a bowling ball in accordance with the invention; and
FIG. 5 is a view, similar to FIG. 1, illustrating both a modification of the bowling ball structure and steps in the method of the invention.
As illustrated in FIGS. 1 and 5, bowling balls constructed and manufactured according to the present invention comprise an outer spherical shell or veneer Ii and an inner core 12 bonded within and to the veneer. In the form of ball shown, the interface, designated 14, between the core and veneer is substantially spherical so that the veneer would be of substantially uniform thickness if the outer spherical surface of veneer 10 and interface 14 are developed about the same center. Inner core 12, only a portion of which is shown, may in turn, comprise an outer shell bonded around a center insert which determines the weight of the ball. The ball will include the usual thumb and finger holes (not shown) which, as a general rule, are formed by drilling at some time subsequent to manufacture. The outer shell or veneer 10 is composed of a relatively heavy, abrasion and impact resistant natural or synthetic polymeric material, as is at least an outer layer or shell of the core, while the insert (if any) comprising the core is formed of a relatively light solid cellular material and of a volume and density designed to produce a ball of predetermined overall weight.
In accordance with the invention, an inlay member 16 is embedded in veneer 10 to provide a distinctive design or character, or a medium which may be conveniently enscribed, for a number of reasons such as identifying the manufacture, dealer, owner, model, style, weight, etc., of a particular ball. The inlay member is securely bonded within the veneer and includes an outer surface at least the peripheral portions of which are contiguous and flush with the outer spherical surface of the veneer and, of course, no portion of the inlay projects beyond the sphere which is the outer surface of the ball. The inlay itself may have a distinctive shape or form, as shown in FIGS. 2 and 3, or it may be designed to provide a surface suitable for embossing or engraving of any desired indicia including designs, letters, numerals, and the like.
The primary difliculty with inlaying designs or characters into bowling balls arises from the obvious fact that such balls are subjected to severe impact stresses which cause inlays to loosen and/or become dislodged. The solution to this problem of secure retention of the inlay is found in a particular ball and inlay construction and a method of manufacturing the ball including the inlay member. Inlay member 16 is composed of an impact resistant polymeric material which is the same as or similar to the materials comprising the veneer and inner core and may, in fact, differ therefrom only in color. This, as will become apparent hereinafter, contributes, as a result of the manufacturing process of the invention, to improved bonding between the inlay member and other components, namely veneer and core, of the ball.
Generally, the composition of the outer layers of the ball including veneer 19 and at least the outer layer or shell of core 12, consist of one or more of a wide variety of natural and synthetic polymers. These include natural rubber such as cis-1,4-polyisoprene or a synthetic rubber such as butadiene-styrene, neoprene, butyl rubber, etc., or combinations thereof. Curing of these materials is effected at elevated temperatures by suitable chemical agents such as sulfur, selenium, tellurium, organic peroxides and certain organic sulfur compounds such as the alkali disulfides. Alternatively, this material may consist of a synthetic plastic including, as typical ingredients, an acrylic polymer and a polyester resin with best results being obtained when, by total weight of the composition, the polyester ranges from 55% to 65% and when the acrylic ranges from 45% to 35%. For further examples of materials and compositions useful in the construction and manufacture of bowling balls according to the present invention, reference may be had to the copending US. patent application of George H. Twickler, Ser. No. 366,364, filed May 11, 1964.
In the preferred method of manufacturing the bowling ball (described in detail in the aforementioned application), the shell of veneer 1t and core 12 are formed separately of polymerizable materials, are assembled and then polymerized to bond the components together as an integral body. The outer shell of the core, in the case of a two component core, is formed as two hemispherically shaped sections by compressing a mass of material of a putty-like consistency within an appropriately formed mold or die. The solid center insert is then placed between the shell sections which are then pressed into adherence with one another and the center insert. During this process, the material of the shell of the core remains in an unpolymerized condition. Veneer it is formed in much the same manner as two hemispherically shaped shells of unpolymerized material by compression of the veneer composition within a die or mold. The final assembly operation is illustrated in FIG. 4 and includes introducing core 12 between the two shell sections of veneer and compressing the veneer against the core to adhere the shell sections and core to one another. This step may be conveniently performed with a die comprising two components 18 and 20 having concave hemispherically shaped surfaces. Die component 18 is mounted on the upper, fixed cross member 22 of a conventional press designated 24 and die component 20 is mounted on the lower movable cross member 26 of the press which includes a ram for forcing die 26 into registration with die 18.
Inlay member 16 is formed of a polymerizable material which is the same as or similar to the material comprising the venteer and may differ therefrom only in its color. The inlay member is formed by compressing the polymerizable material in a suitably shaped die and in the form shown in FIG. 2 comprises a generally conical anchor portion 39, that is, a portion having a circular cross section, and a radially projecting flange 32 on the inner or larger end of portion 30. Anchor portion 35! has a height approximately equal to or less than the thickness of the veneer while the flange is relatively thin and is formed with a plurality of openings 34 which help to insure dimensional stability during manufacture (assembly) of the components of the ball, as well as contributing to the overall strength and stability of the structure.
The cross sectional configuration of the anchor portion and, hence, the portion visible exteriorly of the ball may be varied substantially so long as it tapers from its inner end toward its outer end. This taper is important to insure that the inlay member cannot be dislodged from the veneer in which it is embedded. Another and more complex form of inlay member is shown by way of example, in FIG. 3. This inlay member, designated 35, is formed with a tapered anchor portion 38 having an E-shaped cross section and a flange 40 with openings 42; and is shown as an example of manner and extent to which the cross sectional configuration of the inlay member can be modified so as to present almost any desired visible design or indicia. In the form of inlay shown in FIG. 3, the inner end surface of the inlay member as well as the outer surface of flange 4t), have been formed with generally spherical configurations so as to conform generally to the interface 14. While curving the flange prior to assembly, as described, maybe particularly desirable when inlay members of relatively large cross sections are incorporated in balls with relatively thin veneers, it is not essential and the requisite curvature may be imparted during final assembly of the ball instead of during forming of the inlay member.
Following its formation, the inlay member is partially polymerized, for example, by the application of heat and pressure in a suitable die. This is to provide an inlay member which is substantially more rigid and dimensionally stable than the other components of the ball, particularly veneer 19 and core 12, so that the inlay will retain its shape when pressed into the veneer during assembly. Polymerization of the inlay member is only partial prior to assembly and is completed subsequent to assembly in order to insure a secure bond between the material of the inlay member and veneer and core of the ball.
The components of the ball are assembled, as shown in FIG. 4, by positioning one hemispherical section of veneer 10 in upper die component 18, locating the other hemispherical section of veneer 10 in lower die component 2d, inserting core 12 between the sections of the veneer and inserting partially polymerized inlay member 16 between the core and one (the upper) of the sections of the veneer with the inner end of the inlay member resting against the core. The die components are then pressed toward one another forcing the anchor portion of the inlay member outwardly into the veneer. This will, of course, result in some displacement of the material of the veneer and possibly the core as well, depending upon the relative resistance to flow of the two materials. The die component adjacent the inlay member (in this example, the upper one) may be suitably vented to permit escape of excess displaced material, while some of the displaced material of both the core and veneer enters the openings (34 or 42) in the flange (32 or 40), with the openings providing spaces into which material of the core can be displaced. The inner end of the inlay member includin the flange may be pressed to a slight extent into core 12 and the flange is, of course, engaged between the veneer and core so that the inlay member is securely anchored against movement relative to both veneer and core.
The ball assemblage comprising the veneer, core and inlay member is removed from the die in which it is formed and the entire assemblage is then polymerized by heating Within a mold to convert the assemblage to an integrated polymerized mass of spherical shape. This spherical mass may be oversized and following completion of polymerization, is then reduced, as by grinding and polishing, to its final size, shape and finish, as shown in FIG. 1. In one method of manufacture and assembly encompassed by the invention, the length (radial dimension) of the inlay member is less than the thickness of veneer so that the outer end of the inlay member is beneath the outer surface of the veneer, as shown in FIG. 5, prior to finish grinding of the veneer. By assembling the ball in this manner, it is assured that the inlay member will not be compressed, and possibly distorted, by the die in which assembly is accomplished. The oversized polymerized assembly of FIG. 5 is then ground to reveal the inlay member and provide an outer spherical finished surface 44 (designated by broken lines) which is continuous and includes the inlay member.
The method of the invention thus provides an improved bowling ball structure including a visible inlay member which is an integral part of the ball securely retained against loosening and dislodgment.
Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
What is claimed is:
1. A bowling ball comprising an outer veneer and an inner core, said veneer being a shell having an exterior spherical surface and an interior spherical face, said core being substantially solid and having an exterior spherical face, at least one inlay including an anchor portion and a flange portion, said flange portion having an inner face embedded in said exterior face of said core and an outer face embedded in said interior face of said veneer and being at the interface between said core and said veneer, said anchor portion having side faces that are convergently tapered away from said flange portion toward said exterior surface of said veneer and an exterior surface that is fiush with said exterior surface of said veneer, said fian e portion entirely surrounding the inner extremity of said anchor portion, said flange portion beiru characterized by a series of interface openings extending through said flange portion from said inner face of said flange portion to said outer face of said flange portion, said series of interface openings surrounding said inner extremities of said anchor portion, the material of said core being polymerized, the material of said inlay being polymerized, said material of said veneer and said material of said inlay at the interface therebetween being fused, said material of said core extending outwardly into said interface openings and said material of said veneer extending inwardly into said interface openings, said material of said core and said material of said veneer being in contact within said interface openings, the exterior surface of said veneer and the exterior surface of said anchor portion being ground and polished, said material of said inlay and said material of said veneer being of different colors, said material of said veneer being substantially heavier and harder than said material of said core, said exterior surface of said anchor portion of said insert appearing as a symbol visually contrasting with said exterior surface of said veneer.
References Cited UNITED STATES PATENTS 2,839,853 6/1958 Giangreco 40-327 FOREIGN PATENTS 521,056 5/1940 Great Britain.
ANTON O. OECHSLE, Primary Examiner. G. J. MARLO, Assistant Examiner.
Citations de brevets