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Патент USA US3044787

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July 17, 1962
Filed Oct. 19 , 1959
2 Sheets-Sheet 1
M42” M ?ns-0 MA /v
6 LA’
July 17, 1962
Filed Oct. 19, 1959
2 Sheets-Sheet 2
BY 6
United States L "
(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
Filed Oct. 19, 1959, Ser. No. 847,196
13 Claims. (Cl. 273-452)
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 résumé 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
Mark M. Friedman, Inglewood, Cali?, assignor to Fiber
mold Corporation, Torrance, Cali?, a corporation of
owners wish to install the all-plastic pins across their
This invention relates to bowling pins, more particu
larly to bowling pins molded of plastic material; and is a
continuation-in-part of the copending application?led
December 6, 1957, Serial No. 701,057, entitled “Bowl
ing Pin.”
Patented ‘July 17, 1 962‘
a comparable action and scorability, and to produce a
maple wood, or of maple wood coated with a thin coating 15
sound closely simulating the sound produced by maple
bowling pins ‘when struck by the bowling ball and by each
of thermoplastic material. The de?ciencies of the all
wooden pins and the plastic-coated wooden pins are well
known by informed people in the trade.
In the ?rst place, the wood from which both types of
other during pin action on the alley.
Second, to provide a plastic bowling pin which is capa
ble of withstanding impacts of a bowling ball and impacts
from other bowling pins without splitting, cracking, or
Bowling pins now in common use are either made of
pins are made is a natural forest product with many
chipping, and which, in ‘fact, remains in virtually its initial
random variations in grain strength, depending on the
conditions of climate and rainfall ailecting its growth.
condition after many thousands of lines, that is, long be
yond the life of a maple bowling pin even though the life
In the second place, as a direct result of the ‘foregoing,
of the maple bowling pin is prolonged by repeated recon
ditioning 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
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.
cost per line to the bowling alley operator is materially
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 initial cost and the constant maintenance of these
pins is an expensive “headache” to the bowling alley
the region of ball-impact by the bowling ball, and opti
proprietor. Furthermore, although his conscience may
mum hardness and strength at the bottom of the bowling
deplore it, he must continue to use pins far beyond their
pin so that the stability of the bowling pin is not changed
useful life. The patron or bowler is not usually aware of
nor impaired with constant use.
this because he is too far from the bowling pins to in
spect them. Still, the bowler’s game is adversely affected
whenever he bowls on wooden pins that have exceeded
corporates a novel means of producing an essential musi
Fourth, to provide a plastic bowling pin which in
cal note closely simulating the ring of a wooden pin in
good condition.
Fifth, to provide a plastic bowling pin wherein the
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 construc
hibit the proper action typical of good quality wooden
tion of new alley beds, now totalling over 75,000 individ
- ual alley beds throughout the United States, has over
taken the slow natural process of maple-tree growth.
The most logical answer to this problem is a com
pletely synthetic pin, a pin constructed completely of
center of gravity is located in the region corresponding
to the center of gravity of a wooden pin, thereby to ex
With the above and other objects in view, as may ap
pear hereinafter, reference is directedvto the accompany?
ing drawings in which:
FIGURE 1 is a top view of the bowling pin;
FIGURE 2 is a longitudinal sectional view through
2——2 of FIGURE 1 showing one form of internal con
synthetic material, such as plastic, that can be reproduced
exactly the same, time‘ after time, a pin that does not de
pend on conditions of climate or rainfall for its strength,
a pin that has no grain weaknesses subject to splitting,
FIGURE 3 is a transverse sectional view through 3-3
and cracking, a pin that has no thin plastic ‘cover that
of FIGURE 2»;
may delaminate from the main body of the pin, a pin that
FIGURE 4 is a sectional view through 4-4 of FIG
will outlast wooden pins by thousands of lines with a low 55 URE 2;_
maintenance cost, resulting in a low net cost per line for
FIGURE 5 is a longitudinal sectional view of a modi
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 ?rst of these is proper action or scorability. The
history and tradition of the game of bowling requires that
?ed form of bowling pin;
FIGURES 6, 7, 8, 9, and 10 are transverse sectional
views thereof taken through 6——6, 7‘—7, 8—8‘, 9—9, and
10-40, respectively, of FIGURE 5;
FIGURE 11 is a partial side, partial sectional view
showing'a modi?ed form of the bottom member;
FIGURE 12 is a transverse sectional ‘view through
12-12 of FIGURE 1l.'
' there be no sudden changes in scoring conditions.
Past 65 Reference is ?rst directed to FIGURES 1 through 4.
records are constantly compared ‘with present results, and
The bowling pin here illustrated includes a body mem
it is essential that no fundamental changes occur that
her 1 molded of plastic material. Externally, the body
would alter these comparisons. This problem when an
member is contoured to de?ne a belly 2, neck 3, and head
alyzed and reduced to its essence can ‘be stated in this
4 of the bowling pin. The belly portion of ‘the body
way: (1) a similar percentage of strikes should occur 70 member 1 is hollow Ito de?ne a cylindrical portion 5 and
with a ball thrown in the pocket, slightly high up on the
a conical portion 6, terminating in a rounded apex.
pocket, or slightly thin to the right of the pocket; and
Molded within the neck 3 and head 4 of the body mem
ber 1 is a reinforcing tube 7 formed of material having
Titanium dioxide—l lb. and 272 grams.
a greater strength than the material of the body member
itself. The reinforcing tube 7 may be formed of metal,
In the above formulation LT denotes a high elongation
but is preferably formed of a high strength plastic mate
low ?ow material whereas the numeral 1000 indicates
in only the color of the Cycolac. Hycar 1411 is a butadiene
A bore 8 extends upwardly from the conical portion 6
acrylonitrile rubber in ?nely divided form and of high
to a point approximately midway of the reinforcing tube
acrylonitrile content. The Chlorowax 40 is a chlorinated
7. At this point the bore 8 forms a constricted portion
para?in containing 40 percent combined chlorine.
9 which is closed by a small plug 10. Above the con
As previously stated, the Cycolac is an ABS polymer
stricted portion the bore 8 is enlarged to form a sound 10 whereas Hycar speci?ed above is a resin (copolymer)
chamber 11 which extends to the upper end of ‘the head
comprising acrylonitrile 35 %~50% and butadiene 65 %
4. The reinforcing tube 7 may also extend to the upper
50%. In the above example of the Hycar the acryloni
end of the head or may terminate short of the upper end.
trile is 42% and butadiene is 58%. The above example
The bores 8 and 11 serve to center the pins during the
has a Shore D hardness of 48, a speci?c gravity approxi
molding of the body member to ensure concentric lo
mately 1.01, and a tensile strength of approximately 1500
cation of the reinforcing tube 7.
lbs/sq. in.
The body member 1 receives a bottom member 12 also
The above formulation has been particularly satisfac
formed of plastic material. The bottom member is
tory for the following reasons:
molded to form externally an essentially flat base 13 and
(1) The sound produced is closer to that produced
a conical side portion 14 which diverge upwardly to‘ the
by wooden pins than many other ‘formulations which were
lower end of the belly 2 of the body member 1. The
conical side portion 14 terminates at a shoulder 15, and
(2) The bounce approaches close to that of wooden
the bottom member 12 continues to form a cylindrical
shell or reinforcing sleeve 16 which extends upwardly
(3) The impact strength is excellent, and the body does
into the cylindrical portion 5 of the body member I.
not crack or chip like wood. Furthermore, it maintains
The reinforcing sleeve 16 may be bonded to the cylindrical
its original contour and dimensions so that throughout
portion 5 of the body member 1 by a cement comprising
the life of the pin the otiicial ABC dimensions can be
essentially the plastic corresponding to the plastic from
which the parts are molded and a solvent to obtain a
As pointed out previously, the reinforcing tube 7 is
chemical fusion or weld of that body member and bot
also formed of plastic material and may be of Cycolac,
that is, an ABS polymer, the formulation being such as
tom member.
Preferably, however, an epoxy resin cement such as a
to provide maximum strength. A particular formulation
reaction product of bisphenol-A, and epichlorohydrin,
100 parts by weight, and a polymeric amine curing agent,
of Cycolac having a Shore D hardness of 80, a speci?c
100 to 150 parts by weight, a ratio of 100 parts of the re
7500 lbs/sq. in. has been found to be satisfactory.
In practice, the reinforcing tube is extruded or other
gravity of approximately 1.06, ‘and tensile strength of
action product and 115 parts of the curing agent, has been
found particularly satisfactory, in that a bond is formed
wise molded and then cast as an insert in the body mem
ber 1. While a metal reinforcing tube 7, such as an
which is actually stronger than the bottom member and
body member. In either case, the cement 17 upwells 40 aluminum tube, is satisfactory as a reinforcing, the plastic
‘reinforcing tube offers the advantage of less density and
above the reinforcing sleeve 16, as indicated in FIG
therefore contributes to the lowering of the center of
URE 2.
gravity of the bowling pin.
The bottom member 12 is solid to approximately the
Reference is ‘directed to FIGURES 5 to 10. The bowl
level of ‘the shoulder 15 except for a center hole or socket
ing pin here illustrated is constructed of essentially the
18, in accordance with the standard for wooden pins of
45 same materials as that of the ?rst described bowling pin.
the American Bowling Congress.
The modi?ed bowling pin di?e-rs from the ?rst described
While various plastic materials may be employed in
structure in that a telescoping sleeve 19 is substituted for
the construction of the bowling pin, Cycolac which is an
the reinforcing sleeve 16.
ABS copolymer, i.e., a resin comprising acrylonitrile
l5%-35%, butadiene '20%—50%, and styrene 15%—65% 50 The telescoping sleeve 19 is relatively thin and is pro
vided near its upper end with a small shoulder 20 which
by weight has been found suitable. The letters “ABS” as
serves to support a disk 21. In the construction here
used above are merely the initials of the three constituents
illustrated, the disk 21 is formed of Marine plywood and
of the resin. This material has a tensile strength of 1500
has a central opening 21a. The disk serves to reinforce
7500 lbs/square inch; a Shore D hardness between 40
the sleeve 19 in the region of impact.
90; and an impact strength of 4-10 ft./ in. of Izod notch.
Also in this construction, a central boss 22 is provided
Tests have shown that a particular formulation, namely,
from which extends a pair of diverging webs 23. The
H2003 Cycolac is particularly satisfactory for the base.
webs 23 form with the surrounding wall of the bottom
This formulation has a Shore D hardness of 73, a speci?c
member 12 a pocket in which is cast an eccentric mass
gravity of 1.03, and a tensile strength of 5000 lbs/sq. in.
The numerals 2003 constitute merely a color code indicat 60 24 which may be formed of plastic capable of bonding
to the material of the base member and which may con
ing a particular white whereas the letter “H” denotes a
tain a ?ller or weighting material to increase its density.
molding grade of the material.
The purpose of the eccentric mass 24 is to introduce a
The body member 1 is also formed of Cycolac or a
predetermined unbalance to the bowling pin in keeping
Cycolac-Hycar formulation. It is desirable, however,
that the hardness of the body member be less than the bot
tom member 12, for example, a Shore D hardness be
tween 40-50 has been found satisfactory. A particular
formulation which has been found satisfactory is as fol
Cycolac LT-—16 lbs.
Cycolac Hl000-—16 lbs.
Hycar 1411--7% lbs.
Chlorowax 40-5 lbs. and 45 grams.
Dioctyl sebacate-S lbs. and 45 grams.
with the unbalance which is inherent in wooden bowling
pins. For example, wooden bowling pins vary in ec
centricity of their center of gravity between 0 and 100
gram-centimeters of torque. An eccentric mass is se
lected 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 rein
force 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
same to the exact details of the constructions set forth, and
it embraces such changes, modi?cations, and equivalents
by a binder 28 of plastic material. '
of the parts and their formation and arrangement as come
In each of the constructions illustrated, the cavity
within the purview of the appended claims.
formed by the body member 1 and bottom member 12
What is claimed is:
functions as a sound-modifying chamber, and contributes
l. A bowling pin formed of molded plastic material,
to the production of a sound closely analogous to that
comprising: a unitary molded body member de?ning ex
of a wooden pin when the pin is struck. The sound
ternally the belly, neck, and head of a bowling pin, and
chamber 111, which is open to the upper end of the pin,
having a generally cylindrical cavity extending upwardly
is particularly effective to produce a ring closely anal 10 therein from its under end; and a unitary molded ‘bottom
ogous to the characteristic ring of a maple wooden pin.
member including a flat base and side walls completing
the external contour of the bowling pin, and having a gen
That is, this chamber or socket produces, when the bowl
erally cylindrical tubular shell extending snugly into said
ing pin is struck, a vibrating column of air similar to a
Xylophone pipe.
cavity with the generally cylindrical surfaces of said shell
and cavity bonded together to de?ne a joint extending
It has been ‘found that a particularly satisfactory musi
longitudinally of said bowling pin.
cal note is produced when the diameter of the sound
2. A bowling pin as set forth in claim 1, wherein: said
chamber -11 is approximately 1” and its depth is approxi
body member has a Shore D hardness of between; 40 and
mately 3". Thus the sound produced by the open end
70 and said bottom member has a Shore D hardness of .
sound chamber 11 and the sound produced by the larger
closed sound chamber formed by the body member 1 20 between 55 and 90; said bottom member being appreciably
harder than said body member.
and bottom member 12 complement each other in pro
3. A bowling pin as set forth in claim 1, wherein: the
ducing the rather complex sound inherent in a wooden
head of said bowling pin is provided with a socket open
at its upper end and tending to produce a sound when said
It should be noted that wooden bowling pins after a pre
determined conditioning period, that is, after about 100 25 bowling pin is struck.
4. A bowling pin formed of molded plastic material,
lines of play, become ?attened in this region, and when
comprising: a unitary molded ‘body member de?ning ex- .
so ?attened their scoring characteristics improve. The
ternally the belly, neck, and head of a bowling pin, said
plastic material found satisfactory in the construction of
the present bowling pin does not deform permanently
member having a longitudinal bore, including an enlarged
pensate for the extra density of the plastic material so
that the completed plastic bowling pin weighs the same as
portion initially slidable snugly within the enlarged cavity
a wooden or maple wooden pin, or within the American
joint extending longitudinally of said bowling pin.
in the manner of a wooden bowling pin; therefore, if 30 generally cylindrical cavity extending upwardly from the
lower end of the body member; reinforcing means in the
desired‘, a ?attened or cylindrical surface 29 may be in
neck portion of said body member; a unitary molded
itially provided in the region of impact of the bowling
bottom member de?ning the base and side walls of the
ball, as indicated in FJGURE ‘5.
bowling pin complementary to said body member, said
It should be observed that the accumulative volume
bottom member including a generally cylindrical'tubular
of the cavity within the bowling pin is calculated to com
Bowling Congress weight limits (2 lbs.-, 14 oz. to 3 lbs. 10
in said body member; and an adhesive bonding said tubu
lar portion to the walls of said enlarged cavity, to form a
5. A bowling pin as set‘for-th in claim 4, wherein: said
body member has a Shore D hardness of between 40 and
Partly by reason of the solid bottom member shown
70 and said bottom member has a Shore D hardness of
in FIGURE 2, and the mass added to the constructions
between 55 and 90; said bottom member being appreciably
shown in FIGURES 5 land 11, and partly by control of
harder than said body member.
the densities of the body and base structures and by their
6. A bowling pin as set forth in claim 4, wherein: the
wall thickness, vertical location of the center of gravity 45 head
of said bowling pin is provided with a socket open
is established within the range of the center of gravity in
at its upper end and tending to produce a sound when said
wooden bowling pins.
bowling pin is struck.
Tests have indicated that plastic bowling pins con
7. A bowling pin as set forth in claim 4, wherein: the
structed in accordance with this invention not only per
tubular portion of said bottom member is relatively thick
form in a manner closely simulating a perfect wooden
throughoutits length and reinforces the belly of said body
bowling pin, but also have extremely long lives. A service
life of 10,000 “lines” without repair appears feasible. This
8. A bowling pin as set forth in claim 4, wherein: the
is in excess of four times the life of wooden pins that
tubular portion of said bottom member is relatively thin
have been carefully re?nished several times.
and provided with a reinforcing disk at its inner portion in
However, the plastic pins herein disclosed may also be 55 the plane of impact of a bowling ball against said body
re?nished. 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
9. A bowling pin as set forth in claim 4, wherein: said
bottom member is provided with an eccentric mass.
necessary to hold it vertically on a ?at surface heated to
10. A bowling pin as set forth in claim 4, wherein: said
about 300° F. for 15 or 20 minutes and the base will 60 body member and bottom member de?ne internally a
return to its initial flat condition.
closed sound chamber in the region of the belly, and the
If more elaborate treatment is desired, as for example to
head of said body member forms an open sound chamber
remove scratches, the base ends may be dipped in a solu
extending into said head from the upper end thereof.
tion of Cycolac and methylethy-l ketone, then baked to
11. A bowling pin, comprising: an upper unitary mem
remove the solvent. A solution of 20% Cycolac and 80% 65 ber and a lower unitary member, each molded of plastic
methyl ethyl ketone and a baking period of approximately
material having a speci?c gravity greater than wood; one
three hours at 150° to 180° F. has been found satisfactory.
of said members having a generally cylindrical socket in
The base end can then be machined to its initial measure
one end and a stop rim bordering said socket and de?ning
.ments. The base end of the plastic bowling‘ pin is with
a plane at right angles to the axis of said member; the
either treatment fully as good as a new pin, which is not 70 other of said members having a generally cylindrical shell
the case with the re?nishing of a wooden pin. Still fur
ther, the entire plastic bowling pin may be similarly dipped
after several thousand lines.
While particular embodiments of this invention have
dimensioned to ‘?t 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 de?ne a generally cylindrical joint extending longitudi
been shown and described, it is not intended to limit the 75 nally of the pin; the cylindrical shell of said other member
also having a socket confronting and communicating with
the socket of the ?rst 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
sioned 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 vand neck portions thereof.
References Cited in the ?le of this patent
molded body member de?ning externally the head, neck,
and belly of the bowling pin and extending to a level sub 10
stantially 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 gen
Bishop ______________ __ May 11, 1926
erally cylindrical cavity extending upwardly therein from
Smith ________________ __ Oct. 19,
German et a1. ________ _.. July 25,
Schroeder et al. ______ __ Dec. 25,
Dettman ____________ __ July 2,
its under end to a level above said plane; a unitary molded 15
bottom member of greater hardness than said body mem
ber including a ?at base and side walls completing the
Whelan _____________ __ Feb. 24, 1914
Miller ______________ __ Feb. 26, 1918
external contour of the bowling pin, said bottom member
having a generally cylindrical tubular shell extending snug
Encyclopedia, 1949, pages 104 and 107
ly into said cavity, the generally cylindrical walls of said 20
shell and cavity being bonded together to form a longi
Modern Plastics for September 1955; pages 104-108
tudinally extended joint; said body and ‘bottom members
forming internally a closed chamber so located and dimen
and 225-228 cited.
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