US3044777A - Bowling pin - Google Patents

Description

July 17, 1962 M. M. FRIEDMAN BOWLING PIN 2 Sheets-Sheet 1 Filed Oct. 19 1959 INVENTOR. fins-0 MA /v ATZO//VZ/S y 1962 M. M. FRIEDMAN 3,044,777

BOWLING PIN Filed Oct. 19, 1959 2 Sheets-Sheet 2 ATTORNEYS there be no sudden changes in scoring conditions.

3,044,777 Patented July 17 1 962 ice 3,044,777 BOWLING PIN Mark M. Friedman, Inglewood, Califi, assignor to Fibermold Corporation, Torrance, Califi, a corporation of California Filed Oct. 19, 1959, Ser. No. 847,196 13 Claims. (Cl. 273-452) This invention relates to bowling pins, more particularly to bowling pins molded of plastic material; and is a continuation-in-part of the copending applicationfiled December 6, 1957, Serial No. 701,057, entitled Bowling Pin.

Bowling pins now in common use are either made of maple wood, or of maple wood coated with a thin coating of thermoplastic material. The deficiencies of the allwooden pins and the plastic-coated wooden pins are well known by informed people in the trade.

In the first place, the wood from which both types of pins are made is a natural forest product with many random variations in grain strength, depending on the conditions of climate and rainfall ailecting its growth.

In the second place, as a direct result of the foregoing, both types of pins have a relatively short useful life. Cracking along the grain, in the case of the all-wooden pin, or delamination of the plastic coating, in the case of the plastic-coated pin, usually occurs between 300 and 500 lines of play. The usual practice is to recondition these pins at least three or four times to prolong the life as long'as possible before discarding the pins entirely. The initial cost and the constant maintenance of these pins is an expensive headache to the bowling alley proprietor. Furthermore, although his conscience may deplore it, he must continue to use pins far beyond their useful life. The patron or bowler is not usually aware of this because he is too far from the bowling pins to inspect them. Still, the bowlers game is adversely affected whenever he bowls on wooden pins that have exceeded their relatively short useful life.

In the third place, the entire problem is now seriously aggravated by a shortage of the proper maple woods used in bowling pins. The tremendous growth of the sport of bowling during the past decade along with the construction of new alley beds, now totalling over 75,000 individual alley beds throughout the United States, has overtaken the slow natural process of maple-tree growth.

The most logical answer to this problem is a completely synthetic pin, a pin constructed completely of synthetic material, such as plastic, that can be reproduced exactly the same, time after time, a pin that does not depend on conditions of climate or rainfall for its strength, a pin that has no grain weaknesses subject to splitting, and cracking, a pin that has no thin plastic cover that may delaminate from the main body of the pin, a pin that will outlast wooden pins by thousands of lines with a low maintenance cost, resulting in a low net cost per line for the bowling alley owner, a pin that will provide the patron with a consistent and unchanging pin for game after game.

All these fundamental attributes are provided by an all-plastic pin of the proper design. But this alone is not enough. In order for the all-plastic pin to be accepted by the trade, two additional attributes must be provided.

The first of these is proper action or scorability. The history and tradition of the game of bowling requires that Past records are constantly compared with present results, and it is essential that no fundamental changes occur that would alter these comparisons. This problem when analyzed and reduced to its essence can be stated in this way: (1) a similar percentage of strikes should occur with a ball thrown in the pocket, slightly high up on the pocket, or slightly thin to the right of the pocket; and

(2) a similar set of pin leaves should be expected from a ball which does not strike full in the pocket.

The second attribute is that of sound. Although all the other problems may be solved, and the bowling alley owners wish to install the all-plastic pins across their alleys, unless the sound is close in character and quality to the wooden pins, the patron will be slow to accept it.

With the foregoing rsum of the problem in mind, the objects of the present invention include:

First, to provide a plastic bowling pin which duplicates closely the observable characteristics of a maple bowling pin when in good condition, more particularly, to exhibit a comparable action and scorability, and to produce a sound closely simulating the sound produced by maple bowling pins when struck by the bowling ball and by each other during pin action on the alley.

Second, to provide a plastic bowling pin which is capable of withstanding impacts of a bowling ball and impacts from other bowling pins without splitting, cracking, or chipping, and which, in fact, remains in virtually its initial condition after many thousands of lines, that is, long beyond the life of a maple bowling pin even though the life of the maple bowling pin is prolonged by repeated reconditioning and repair; thereby providing a bowling pin which, though having a higher initial cost than maple bowling pins, has instead such prolonged life that the net cost per line to the bowling alley operator is materially reduced.

Third, to provide a plastic bowling pin which utilizes a novelly constructed body member and bottom member of different Shore hardness to provide optimum resilience in the region of ball-impact by the bowling ball, and optimum hardness and strength at the bottom of the bowling pin so that the stability of the bowling pin is not changed nor impaired with constant use.

Fourth, to provide a plastic bowling pin which incorporates a novel means of producing an essential musical note closely simulating the ring of a wooden pin in good condition.

Fifth, to provide a plastic bowling pin wherein the center of gravity is located in the region corresponding to the center of gravity of a wooden pin, thereby to exhibit the proper action typical of good quality wooden p ns.

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompany ing drawings in which:

FIGURE 1 is a top view of the bowling pin;

FIGURE 2 is a longitudinal sectional view through 22 of FIGURE 1 showing one form of internal construction;

FIGURE 3 is a transverse sectional view through 3-3 of FIGURE 2;

FIGURE 4 is a sectional view through 4-4 of FIG- URE 2;

FIGURE 5 is a longitudinal sectional view of a modified form of bowling pin;

FIGURES 6, 7, 8, 9, and 10 are transverse sectional views thereof taken through 66, 77, 88, 99, and 10-40, respectively, of FIGURE 5;

FIGURE 11 is a partial side, partial sectional view showing'a modified form of the bottom member;

FIGURE 12 is a transverse sectional view through 12-12 of FIGURE 1l.' 0

Reference is first directed to FIGURES 1 through 4. The bowling pin here illustrated includes a body memher 1 molded of plastic material. Externally, the body member is contoured to define a belly 2, neck 3, and head 4 of the bowling pin. The belly portion of the body member 1 is hollow to define a cylindrical portion 5 and a conical portion 6, terminating in a rounded apex.

Molded within the neck 3 and head 4 of the body mem- 3 ber 1 is a reinforcing tube 7 formed of material having a greater strength than the material of the body member itself. The reinforcing tube 7 may be formed of metal, but is preferably formed of a high strength plastic material.

A bore 8 extends upwardly from the conical portion 6 to a point approximately midway of the reinforcing tube 7. At this point the bore 8 forms a constricted portion 9 which is closed by a small plug 10. Above the constricted portion the bore 8 is enlarged to form a sound chamber 11 which extends to the upper end of the head 4. The reinforcing tube 7 may also extend to the upper end of the head or may terminate short of the upper end. The bores 8 and 11 serve to center the pins during the molding of the body member to ensure concentric location of the reinforcing tube 7.

The body member 1 receives a bottom member 12 also formed of plastic material. The bottom member is molded to form externally an essentially flat base 13 and a conical side portion 14 which diverge upwardly to the lower end of the belly 2 of the body member 1. The conical side portion 14 terminates at a shoulder 15, and the bottom member 12 continues to form a cylindrical shell or reinforcing sleeve 16 which extends upwardly into the cylindrical portion of the body member I. The reinforcing sleeve 16 may be bonded to the cylindrical portion 5 of the body member 1 by a cement comprising essentially the plastic corresponding to the plastic from which the parts are molded and a solvent to obtain a chemical fusion or weld of that body member and bottom member.

Preferably, however, an epoxy resin cement such as a reaction product of bisphenol-A, and epichlorohydrin, 100 parts by weight, and a polymeric amine curing agent, 100 to 150 parts by weight, a ratio of 100 parts of the reaction product and 115 parts of the curing agent, has been found particularly satisfactory, in that a bond is formed which is actually stronger than the bottom member and body member. In either case, the cement 17 upwells above the reinforcing sleeve 16, as indicated in FIG- URE 2.

The bottom member 12 is solid to approximately the level of the shoulder except for a center hole or socket 18, in accordance with the standard for wooden pins of the American Bowling Congress.

While various plastic materials may be employed in the construction of the bowling pin, Cycolac which is an ABS copolymer, i.e., a resin comprising acrylonitrile l5%-35%, butadiene '20%50%, and styrene 15%65% by weight has been found suitable. The letters ABS as used above are merely the initials of the three constituents of the resin. This material has a tensile strength of 1500- 7500 lbs/square inch; a Shore D hardness between 90; and an impact strength of 4-10 ft./ in. of Izod notch. Tests have shown that a particular formulation, namely, H2003 Cycolac is particularly satisfactory for the base. This formulation has a Shore D hardness of 73, a specific gravity of 1.03, and a tensile strength of 5000 lbs/sq. in. The numerals 2003 constitute merely a color code indicating a particular white whereas the letter H denotes a molding grade of the material.

The body member 1 is also formed of Cycolac or a Cycolac-Hycar formulation. It is desirable, however, that the hardness of the body member be less than the bottom member 12, for example, a Shore D hardness between 40-50 has been found satisfactory. A particular formulation which has been found satisfactory is as follows:

Cycolac LT-16 lbs.

Cycolac Hl000-16 lbs.

Hycar 1411--7% lbs.

Chlorowax 40-5 lbs. and grams. Dioctyl sebacate-S lbs. and 45 grams.

Calcium stearate-14l grams. Titanium dioxidel lb. and 272 grams.

In the above formulation LT denotes a high elongation low fiow material whereas the numeral 1000 indicates only the color of the Cycolac. Hycar 1411 is a butadieneacrylonitrile rubber in finely divided form and of high acrylonitrile content. The Chlorowax 40 is a chlorinated parafiin containing 40 percent combined chlorine.

As previously stated, the Cycolac is an ABS polymer whereas Hycar specified above is a resin (copolymer) comprising acrylonitrile 35 %-50% and butadiene 65 50%. In the above example of the Hycar the acrylonitrile is 42% and butadiene is 58%. The above example has a Shore D hardness of 48, a specific gravity approximately 1.01, and a tensile strength of approximately 1500 lbs/sq. in.

The above formulation has been particularly satisfactory for the following reasons:

(1) The sound produced is closer to that produced by wooden pins than many other formulations which were tried.

(2) The bounce approaches close to that of wooden pins.

(3) The impact strength is excellent, and the body does not crack or chip like wood. Furthermore, it maintains its original contour and dimensions so that throughout the life of the pin the otiicial ABC dimensions can be maintained.

As pointed out previously, the reinforcing tube 7 is also formed of plastic material and may be of Cycolac, that is, an ABS polymer, the formulation being such as to provide maximum strength. A particular formulation of Cycolac having a Shore D hardness of 80, a specific gravity of approximately 1.06, and tensile strength of 7500 lbs/sq. in. has been found to be satisfactory.

In practice, the reinforcing tube is extruded or otherwise molded and then cast as an insert in the body member 1. While a metal reinforcing tube 7, such as an aluminum tube, is satisfactory as a reinforcing, the plastic reinforcing tube offers the advantage of less density and therefore contributes to the lowering of the center of gravity of the bowling pin.

Reference is directed to FIGURES 5 to 10. The bowling pin here illustrated is constructed of essentially the same materials as that of the first described bowling pin. The modified bowling pin difie-rs from the first described structure in that a telescoping sleeve 19 is substituted for the reinforcing sleeve 16.

The telescoping sleeve 19 is relatively thin and is provided near its upper end with a small shoulder 20 which serves to support a disk 21. In the construction here illustrated, the disk 21 is formed of Marine plywood and has a central opening 21a. The disk serves to reinforce the sleeve 19 in the region of impact.

Also in this construction, a central boss 22 is provided from which extends a pair of diverging webs 23. The webs 23 form with the surrounding wall of the bottom member 12 a pocket in which is cast an eccentric mass 24 which may be formed of plastic capable of bonding to the material of the base member and which may contain a filler or weighting material to increase its density.

The purpose of the eccentric mass 24 is to introduce a predetermined unbalance to the bowling pin in keeping with the unbalance which is inherent in wooden bowling pins. For example, wooden bowling pins vary in eccentricity of their center of gravity between 0 and gram-centimeters of torque. An eccentric mass is selected which is within a comparable range.

Reference is directed to FIGURES 11 and 12. In this construction, a disk 25 formed of plastic is substituted for the plywood disk 21, and like the disk 21 serves to reinforce the bowling pin in the region of impact. In this construction, webs 26 radiate in all directions from the internal boss 22 to form a plurality of cavities. In order to provide an eccentric mass, weight elements 27 may be placed in one or more of the cavities and held in place by a binder 28 of plastic material.

In each of the constructions illustrated, the cavity formed by the body member 1 and bottom member 12 functions as a sound-modifying chamber, and contributes to the production of a sound closely analogous to that of a wooden pin when the pin is struck. The sound chamber 1 1, which is open to the upper end of the pin, is particularly effective to produce a ring closely analogous to the characteristic ring of a maple wooden pin. That is, this chamber or socket produces, when the bowling pin is struck, a vibrating column of air similar to a Xylophone pipe.

It has been found that a particularly satisfactory musical note is produced when the diameter of the sound chamber -11 is approximately 1 and its depth is approximately 3". Thus the sound produced by the open end sound chamber 11 and the sound produced by the larger closed sound chamber formed by the body member 1 and bottom member 12 complement each other in producing the rather complex sound inherent in a wooden It should be noted that wooden bowling pins after a predetermined conditioning period, that is, after about 100 lines of play, become flattened in this region, and when so flattened their scoring characteristics improve. The plastic material found satisfactory in the construction of the present bowling pin does not deform permanently in the manner of a wooden bowling pin; therefore, if desired, a flattened or cylindrical surface 29 may be initially provided in the region of impact of the bowling ball, as indicated in FJGURE 5.

It should be observed that the accumulative volume of the cavity within the bowling pin is calculated to compensate for the extra density of the plastic material sothat the completed plastic bowling pin weighs the same as a wooden or maple wooden pin, or within the American Bowling Congress weight limits (2 lbs.-, 14 oz. to 3 lbs. 02.).

Partly by reason of the solid bottom member shown in FIGURE 2, and the mass added to the constructions shown in FIGURES 5 and 11, and partly by control of the densities of the body and base structures and by their wall thickness, vertical location of the center of gravity is established within the range of the center of gravity in wooden bowling pins.

Tests have indicated that plastic bowling pins constructed in accordance with this invention not only perform in a manner closely simulating a perfect wooden bowling pin, but also have extremely long lives. A service life of 10,000 lines without repair appears feasible. This is in excess of four times the life of wooden pins that have been carefully refinished several times.

However, the plastic pins herein disclosed may also be refinished. This may be accomplished more readily than with wooden bowling pins. For example, if the base of a plastic bowling pin should become rounded, it is merely necessary to hold it vertically on a fiat surface heated to about 300 F. for 15 or minutes and the base will return to its initial flat condition.

If more elaborate treatment is desired, as for example to remove scratches, the base ends may be dipped in a solution of Cycolac and methylethy-l ketone, then baked to remove the solvent. A solution of 20% Cycolac and 80% methyl ethyl ketone and a baking period of approximately three hours at 150 to 180 F. has been found satisfactory. The base end can then be machined to its initial measure- .ments. The base end of the plastic bowling pin is with either treatment fully as good as a new pin, which is not the case with the refinishing of a wooden pin. Still further, the entire plastic bowling pin may be similarly dipped after several thousand lines.

While particular embodiments of this invention have been shown and described, it is not intended to limit the same to the exact details of the constructions set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

What is claimed is:

l. A bowling pin formed of molded plastic material, comprising: a unitary molded body member defining externally the belly, neck, and head of a bowling pin, and having a generally cylindrical cavity extending upwardly therein from its under end; and a unitary molded bottom member including a flat base and side walls completing the external contour of the bowling pin, and having a generally cylindrical tubular shell extending snugly into said cavity with the generally cylindrical surfaces of said shell and cavity bonded together to define a joint extending longitudinally of said bowling pin.

2. A bowling pin as set forth in claim 1, wherein: said body member has a Shore D hardness of between; 40 and 70 and said bottom member has a Shore D hardness of between 55 and said bottom member being appreciably harder than said body member.

3. A bowling pin as set forth in claim 1, wherein: the head of said bowling pin is provided with a socket open at its upper end and tending to produce a sound when said bowling pin is struck.

4. A bowling pin formed of molded plastic material,

comprising: a unitary molded body member defining externally the belly, neck, and head of a bowling pin, said member having a longitudinal bore, including an enlarged generally cylindrical cavity extending upwardly from the lower end of the body member; reinforcing means in the neck portion of said body member; a unitary molded bottom member defining the base and side walls of the bowling pin complementary to said body member, said bottom member including a generally cylindrical'tubular portion initially slidable snugly within the enlarged cavity in said body member; and an adhesive bonding said tubular portion to the walls of said enlarged cavity, to form a joint extending longitudinally of said bowling pin.

5. A bowling pin as setfor-th in claim 4, wherein: said body member has a Shore D hardness of between 40 and 70 and said bottom member has a Shore D hardness of between 55 and 90; said bottom member being appreciably harder than said body member.

6. A bowling pin as set forth in claim 4, wherein: the head of said bowling pin is provided with a socket open at its upper end and tending to produce a sound when said bowling pin is struck.

7. A bowling pin as set forth in claim 4, wherein: the tubular portion of said bottom member is relatively thick throughoutits length and reinforces the belly of said body member.

8. A bowling pin as set forth in claim 4, wherein: the tubular portion of said bottom member is relatively thin and provided with a reinforcing disk at its inner portion in the plane of impact of a bowling ball against said body member.

9. A bowling pin as set forth in claim 4, wherein: said bottom member is provided with an eccentric mass.

10. A bowling pin as set forth in claim 4, wherein: said body member and bottom member define internally a closed sound chamber in the region of the belly, and the head of said body member forms an open sound chamber extending into said head from the upper end thereof.

11. A bowling pin, comprising: an upper unitary member and a lower unitary member, each molded of plastic material having a specific gravity greater than wood; one of said members having a generally cylindrical socket in one end and a stop rim bordering said socket and defining a plane at right angles to the axis of said member; the other of said members having a generally cylindrical shell dimensioned to fit snugly in said socket and having a shoulder abutting said rim, the generally cylindrical socket and shell of said members being bonded, each to the other,

' to define a generally cylindrical joint extending longitudinally of the pin; the cylindrical shell of said other member also having a socket confronting and communicating with the socket of the first member to form therewith a sound chamber, the volume and location of said sound chamber being such that said members when joined form a bowling pin having a weight and center of gravity corresponding to that of a wooden bowling pin.

12. A bowling pin formed of molded plastic material having a density greater than Wood, comprising: a unitary molded body member defining externally the head, neck, and belly of the bowling pin and extending to a level substantially below the plane of engagement by a bowling ball to include that portion of the bowling pin 'below said plane most subject to blows, said body member having a generally cylindrical cavity extending upwardly therein from its under end to a level above said plane; a unitary molded bottom member of greater hardness than said body member including a fiat base and side walls completing the external contour of the bowling pin, said bottom member having a generally cylindrical tubular shell extending snugly into said cavity, the generally cylindrical walls of said shell and cavity being bonded together to form a longitudinally extended joint; said body and bottom members forming internally a closed chamber so located and dimensioned that said members form a bowling pin having the weight and center of gravity of a wooden bowling pin.

13. A bowling pin as set forth in claim 12, which also comprises: a reinforcing core of plastic material, having greater strength than said body member, molded within and bonded to the head and neck portions thereof.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Modern Plastics Encyclopedia, 1949, pages 104 and 107 cited.

Modern Plastics for September 1955; pages 104-108 and 225-228 cited.

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