Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
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1. FIELD OF THE INVENTION-
The present invention pertains to bowling pins.
More particularly, the present invention pertains to com-
positions and processes for manufacturing bowling pins.
Even more particularly, the present invention pertains to
bowling pin structures, compositions and processes
therefor.
2. PRIOR ART-
In the sport of bowling there has been developeda plurality of synthetic resinous accoutrements including
bowling balls, shoes, as well as dressings for the lanes,
per se. Yet, the sport has consistently employed and
utilized wooden bowling pins. Although there has been
proposed heretofore bowling pins formed from synthetic
resins, see, inter alia, U. S. Patent 3,268,636, such
bowling pins have not encountered commercial utilization.
One of the major problems encountered with
synthetic bowling pins as differentiated from wooden
bowling pins, is strictly aesthetic. Synthetic bowling
pins do not emit the same sound, upon ball impact, as do
wooden pins. In essence, prior art synthetic bowling
pins emit a muffled or mitted sound as compared to the
resounding noise of wooden pins. This has greatly depre-
ciated the utilization of synthetic bowling pins.
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Another problem encountered with prior art
synthetic bowling pins is durability. Oftentimes, the
prior art synthetic pins could not reach or attain the
impact strength and/or compressive strength of the hard
maple used in conventional bowling pins.
The present invention, as will subsequently be
detailed, provides a bowling pin formed from a synthetic
resin, as well as wood, which overcomes all of the debi-
litating factors of the prior art and which surpasses or
equals the properties of wooden pins.
SUMMARY OF THE INVENTION
In accordance with the present invention there
is provided a bowling pin comprising (a) a synthetic
resinous hollow outer shell and (b) a wooden laminate
neck-carrying core. The core is dimensioned to be
slightly larger than the interior opening or hollow of
the shell or belly. The core is inserted by heating the
shell to expand it and, then, inserting the core.
Thereafter, the assembly is permitted to cool to room
temperature. Thus, the inner core is shrink-fitted into
the shell.
The outer shell or belly is formed by injection
molding a high impact polypropylene in admixture with a
filler and in the presence of a coupling compound and a
surfactant.
~; The products produced in accordance herewith are
comparable to and in many instances surpass conventional
: wooden pins.
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For a more complete understanding of the present
invention reference is made to the following detailed
description and accompanying drawing. In the drawing,
like reference characters refer to like parts throughout
the several views, in which:
BRIEF DESCRIPTION OF THE DRAWING
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FIG. 1 is a side elevational view, partly in phantom, of
a bowling pin in accordance with the present
invention;
FIG. 2 is a cross-sectional view taken along the line 2-2
of FIG. 1;
FIG. 3 is a sectional view taken along the line 3-3 of
FIG. 1;
FIG. 4 is a sectional view tsken along the line 4-4 of
FIG. 1, and
FIG. 5 is a broken, cross-sectional view of an alternate
embodiment of the head of the eore.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, and with reference to the drawing and, in
particular FIGS. 1-4, there is depicted therein a bowling
pin or similar structure, generally denoted at 10, in
accordance with the present invention. The pin 10
hereof, generally comprises an outer shell or belly 12
and an inner core 14.
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With more particularity, the belly 12 comprises
a substantially flat or planar base 16 and an arcuate or
curvilinear sidewall 18. The belly has an open top. The
belly has a hollow interior comprising a first diameter
hollow or bore 20 which extends along a substantial por-
tion of the vertical extent of the belly. The bore 20
terminates into and communicates with a reduced diameter
bore 22. The bore 22 extends upwardly from the base 16.
The belly 12 has a annular recessed groove 24
formed in the base. A nylon ring 26 is emplaced in the
groove in accordance with the requirements of the
American Bowling Congress.
As will subsequently be detailed, the belly 12
is formed from a synthetic resinous material.
The core 14 hereof comprises an integrally
formed cap portion 28, a neck portion 30, a main body
portion 32 and a shank portion 34. The core 14 comprises
a wood laminate of sections 36, 38, and 40 which are
laminated together by any conventional method. The lami-
nated cor,e has a unidirectional grain orientation which
is continuous with the grain of the belly (not shown).
Preferably, a scanned, maple wood laminate having the
unidirectional grain is utilized as the core 14.
The cap portion 28 and the neck portion 30 of
the core are disposed exteriorly of the shell or belly 12
and conform to the conventional head and neck of a
bowling pin. The neck portion 30 is configured to be
continuous
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with the upper edge 42 of the belly. In this manner no
exterior discontinuities are presented.
The main body portion 32 of the core is disposed
within the hollow 20 by shrink fitting, in a manner to be
subsequently described. The portion 32 has a length less
than that of the hollow 20, as shown, and a di~meter
slightly larger than that of the hollow.
A plurality of circular grooves 44 are formed in
the exterior of the main body portion 32. The grooves 32
have an adhesive emplaced therewithin for enhancing adhe-
sion between the core and the interior of the belly. The
grooves 44 are parallel and equidistantly spaced apart
along the vertical extent of the main body portion.
Depending downwardly from the bottom surface of
the main body portion is the shank portion 34 of the core
The shank portion 34 has a diameter slightly larger than
that of the bore 22 and is emplaced therewithin by shrink
fitting. The shank portion 34, extends from the base 16
into the interior of the belly within the hollow 20.
Because the shank portion has a diameter less than that
of the main body portion and has a portion thereof within
the bore 20, there is, thus, defined an annular cavity 46
in the interior of the pin 10. The cavity 46 functions
as a sound chamber for amplifying and reverberating the
sound made upon impact with a ball. Furthermore, the
cavity provides the proper balance to the pin.
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Referring, again, to the drawing, the shank por-
tion 34 has a plurality of grooves 48 circumferentially
disposed therearound. The grooves 48 are formed on the
exterior of the shank portion 34 which lies within the
bore 22. The grooves 48 have an adhesive emplaced
therewithin to promote adherence between the core and the
belly in the manner heretofore described.
A clearly shown in FIGS. 1 and 2, the shank por-
tion 34 has a vertical partial bore 50 formed therein.
The bore 50 is formed centrally in the shank portion and
extends upwardly from the base of the shank into the
interior thereof. The bore 50 receives the fingers of an
automatic pin setting machine (not shown).
In fabricating the pin 10 hereof the exterior is
provided with an outer coating of paint or plastic to
protect the belly and core and which has the conventional
stripings thereon.
Referring, now, to FIG. 5, there is depicted
therein an alternate embodiment of the present invention,
generally, denoted at 110. In accordance herewith the
head 112 of the core 114 includes a recessed portion 116.
The recess 116 extends around the head and has an upper,
substantially flat or planar surface 118. The lower ter-
minus of the recess defines as annular seat or shoulder
120. A channel 122 is formed in the top surface 118 and
depends downwardly therefrom into the interior of the
head portion 112.
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A cap 124 is emplaced in the recess 116 and
seats on the annular shoulder 120. The cap 124 has a
width equal to the width of the recess such that the
exterior wall thereof in contiguous with the exterior
wall of the head portion 112 to avoid outer
discontinuities. The top 126 of the cap has a spherical
configuration to impart a bowling pin cap configuration
to the assembly. The top of the cap 124 has a finger 128
which is shrink fitted into the channel 122 in the same
manner as the core portions are shrink fitted into the
bores of the belly.
The cap 124 is formed from the same synthetic
resin as the belly to impart high impact and compressive
strength to the head of the pin. As is known to the
skilled artisan, it is either the head of the pin or the
belly, but not the neck, which is most often subjected to
impact and compression.
As hereinbefore noted, the belly and, where
used, the cap, is formed from a synthetic resinous
material. The material hereof consists essentially of
(a) a high impact polypropylene and (b) a filler.
The propylene utilized herein is a high impact
polypropylene, prepared by conventional techniques, and
having a specific gravity of about 0.905. Generally, the
polypropylene has an intrinsic viscosity ranging from
about 2.3 to 3.7. Such polypropylenes are well known and
commercially available, such as those sold by Hercules
Chemicals under the codes 8623, 7523 and PC072.
Optimally, a blend of such
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polypropylene are used herein, in any desired proportions.
These polypropylenes have intrinsic viscosities within
the above-defined ranges.
The polypropylene is, generally, employed in an
amount ranging from about seventy-five percent $o about
eighty-five percent, by weight, based on the total weight
of the material.
The other component in the synthetic resinous
material is a filler. The filler, which must be com-
patible~with the polypropylene and be susceptible to
injection molding, generally, is employed in an amount
ranging from about fifteen to about twenty-five percent,
by weight, based on the total weight of the material.
The filler utilized herein is selected from the group
consisting of silicon dioxide, asbestos fibers and mix-
tures thereof. Where utilized as a mixture any desired
proportions of the filler can be utilized.
The belly and/or cap is fabricated from the
synthetic resinous material by the injection molding
thereof. The molding of the material is, generally,
carried out a temperature of from about 400-F to about
500 F. Preferably, the temperature ranges from about
425-F to about 475-F. In injection molding, the present
material, a pressure of about eight thousand pounds per
square inch (psi) is ordinarily employed.
The material is molded in the presence of a
wetting agent and a blowing agent. The wetting agent and
blowing agent are added separately to the material in a
stepwise procedure.
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Specifically, to the material is added, with
agitation, the wetting agent, at room temperature and
pressure. Thereafter, the blend is agitated for about
five to ten minutes.
Next, the blowing agent is added to the blend,
with agitation. The blowing agent is mixed into the
blend for about five to ten minutes at room temperature
and pressure to ensure a homogeneous mixture.
The resulting mixture is then plasticized in an
extruder at the hereinbefore denoted elevated tem-
peratures and pressures. From the extruder the mixture
is then injected into a mold conforming to the desired
configuration of the belly and/or cap.
The wetting agent utilized herein is,
preferably, a synthetic fatty amide wax. More
specifically, the wetting agent is, preferably, a fatty
diamide synthetic wax. A particularly preferred type of
wax is that sold by Glyco Chemicals, Inc. under the name
ACRAWAX C, a trademark, which is utilized as a powdered
wax. ACRAWAX C, a trademark, has the following reported
physical properties:
Melting Point 140- to 145-C
Acid Value 8.5 max.
Gardner - 1963 5 max.
Flash Point 285 C
Specific Gravity ~ 25 C 0.95 to 0.97
Moisture Absorption 0.6% in 48 hours
~ 35 C and 100% RH
ASH Content Less than 0.5%
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As noted, this product is commercially
available. Generally, the wetting agent is employed in
an amount ranging from about 0.25 to 0.5 percent, by
weight thereof, based on the weight of the polypropylene.
The blowing agent is utilized in an amount
ranging from about one to ten percent, by weight, based
on the total weight of the mixture. Preferably, the
blowing agent is utilized in an amount ranging from about
one to five percent, by wwight, based on the total weight
of the mixture.
The blowing agent, per se, comprises an admix-
ture of azodicarbonamide, butylated hydroxy toluene and
calcium silicate. The butylated hydroxy toluene func-
tions as a coupling compound and the calcium silicate
functions to promote agglomeration of the filler and
polypropylene.
The azodiacarbonamide is a commercially
available product which, usually, is in admixture with a
mihor amount of finely divided colloidal or f~me silica.
Such products are defined in British Patent No.
1,360,392.
The blowing agent admixture, preferably, compri-
ses from about 89.75 to about 94.75 percent, by weight,
of the azodicarbonamide; about 0.25 percent, by weight,
of the butylated hydroxy toluene and from about five to
ten percent, by weight, of the calcium silicate.
It should be noted with respect hereto that the
blowing agent can be used in molding polypropylene, per
se, and is not solely restricted to utilization herein.
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In fabricating a bowling pin in accordance
herewith, the belly and cap, if used, are injection
molded by the procedure outlined above. Thereafter, the
belly is heated to render expansible the interior
thereof. Then, the main body portion and shank, having
the adhesive in their grooves, are explaced in their
respective bores such that the exterior of the neck por-
tion of the core is contiguous with the exterior of the
belly and the base of the shank is coplanar with the base
of the belly. Finally, the assembly is permitted to cool
to room temperature whereupon the belly portion
contracts, thereby, shrink fitting the core into the
interior bores by virtue of the appropriate core portions
having a larger diameter than their associated bores.
Thereafter, the cap, if used, is fitted into the recess
of the core head by the same procedure.
The bowling pins produced in accordance herewith
and, as noted thereinabove, are comparable to or surpass
the qualities of 100% wooden pins. To evidence this, a
series of pins were prepared in accordance with the pre-
sent invention. Thereafter, the pins were subjected to
an American Bowling Congress type test and compared to
conventional wooden bowling pins. The results of these
comparisons were as follows:
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TEST WOODEN PIN INVENTIVE PIN
Durability 5,000 bowling 15,000 to 18,000
games, max. bowling games
Center of Gravity (Same for both types of pin)
Radius of Gyration 13.2 to 14.8 14.2
Scleroscope 60 to 62 60 to 62
Weight 3 1/3 to 3~ lbs. 3 lbs. 5 oz.
Scoring 147 to 154 148.7 (average)
Thus, the present pins are comparable in all
physical respects to conventional wooden pins, but with
much greater durability.
Having, thus, described the invention what is
claimed is:
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