U.S. patent number 3,672,031 [Application Number 05/073,131] was granted by the patent office on 1972-06-27 for method of manufacturing plastic bowling pin.
Invention is credited to Maurice Anthony Negrini.
United States Patent |
3,672,031 |
Negrini |
June 27, 1972 |
METHOD OF MANUFACTURING PLASTIC BOWLING PIN
Abstract
This specification discloses a bowling pin of plastic that has
the appearance of a wooden pin, sounds like a wooden pin, and
scores like a wooden pin. These properties are imparted by the
structure comprising a hollow main body, a hollow core with a space
between the core and the body, a removable and replacable cap plug
for the upper end of the core, and a removable and replaceable base
plug for the lower end of the core; and method of manufacturing the
pin of this construction. The present invention relates to blowling
pins, and is concurred primarily with a bowling pin of plastic that
has all the properties that are of vital interest to a bowler, of a
wooden pin and which properties are imparted to the pin by the
structural characteristics thereof.
Inventors: |
Negrini; Maurice Anthony
(Woburn, MA) |
Family
ID: |
22111900 |
Appl.
No.: |
05/073,131 |
Filed: |
September 17, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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836518 |
Jun 25, 1969 |
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882036 |
Dec 4, 1969 |
3572710 |
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Current U.S.
Class: |
29/417; 29/455.1;
29/445; 29/525.01; 29/525.09 |
Current CPC
Class: |
A63D
9/00 (20130101); Y10T 29/49798 (20150115); Y10T
29/49879 (20150115); Y10T 29/49861 (20150115); Y10T
29/49947 (20150115); Y10T 29/49961 (20150115) |
Current International
Class: |
A63D
9/00 (20060101); B23p 017/00 () |
Field of
Search: |
;29/417,445,526,455
;273/82R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Moon; Charlie T.
Parent Case Text
This application is a division of Ser. No. 836,518 filed June 25,
1969 and of Ser. No. 882,036 filed Dec. 4, 1969, now U.S. Pat. No.
3,572,710.
Claims
What is claimed is:
1. In the manufacture of a plastic bowling pin, the method
comprising the steps of:
a. extruding a plastic into a strip of a required cross
section;
b. cutting a block of appropriate length from said strip;
c. machining the outer surface of said block to provide a contour
approximately that of the finished pin;
d. drilling a longitudinal passage in said block to provide bore
sections;
e. milling said block internally from said passage to provide
shoulders and an enlarged cylindrical surface between the
shoulders;
f. assembling a hollow core in said bore passages by insertion
therein leaving a hollow portion therebetween formed by said
enlarged surface;
g. fixing the assembled relation of the body and core; and
h. finally finishing the outer contour of said body and core.
2. The method of claim 1 together with making the hollow core by
the following steps:
i. extruding a plastic into a strip of required cross section;
j. drilling an upper bore in said core strip from the upper end,
and
k. drilling a lower bore into said core strip from the lower
end.
3. The method of claim 2 together with the step of machining the
outer surface of the core in the zone of the lower bore to provide
a desired contour thereon.
4. The method of claim 3 in which external ribs are formed on said
core by the milling of the outer surface thereof.
Description
BACKGROUND OF THE INVENTION
Bowling is a sport now meeting with widespread acceptance. Bowlers,
by virtue of years of experience properties is wooden pins, now
expect certain properties of the pins with which they play. Perhaps
the most important of these properties the sound which comes from
impact with a ball, impact with each other as they fly about, and
engagement with adjacent alley structure. If a plastic pin is to
meet with public acceptance, it is believed it must sound like a
wooden pin.
The manner in which one pin affects another as it engages therewith
after being forcibly removed from its position of rest by impact
with a ball or other pin is also of importance from the aspect of
scoring. The total number of pins which are felled by the delivery
of a ball depends on the reaction of the pins with each other and
with environmental alley equipment. All such reactions should be
the same as those derived from wooden pins.
All the pins of any set, whether duck pins, candle pins, or ten
pins should be of uniform standard weight. Wooden pins are now
produced in which this standardization of weight is achieved to a
degree that is now acceptable. However, it is believed a more
perfect attainment is desirable.
The part of a bowling pin which is subject to the greatest amount
of wear is the base on which the pin rests in erected position.
Next in wear reception is the cap or upper end. It is important
that these elements be easily removable and replaceable.
While plastic bowling pins have been proposed, it is believed that
none of the now available pins accommodate the above outlined
factors to the degree necessary to accord to the pins the
widespread acceptance with which wooden pins meet.
OBJECTS OF THE INVENTION
The present invention has, as its foremost objective, the provision
of a plastic bowling pin which has the properties of a wooden pin
so far as sound and scoring are concerned and which may be
accurately produced in a standard weight.
Another object is to provide a plastic bowling pin having a cap and
a base which are easily removable and replaceable.
A more detailed object is to provide, in a plastic bowling pin, a
structure which affords, in effect, a sound box.
SUMMARY OF THE INVENTION
The foregoing objects are achieved by the plastic bowling pin of
this invention. This pin comprises two main elements. These are: a
main body and a hollow core. The body has an outer contour
corresponding to that of a conventional pin and an inner
cylindrical surface terminating in a shoulder at each end.
Extending from each of these shoulders is a cylindrical surface of
a diameter smaller than that between the shoulders, and which
provides two bore sections of the same diameter and in alignment.
These bore sections receive the core with an empty space or chamber
being defined by the core, shoulders, and cylindrical surface
therebetween
Means are provided for maintaining the core assembled with the
body. This means may take either of two forms. In one form
transverse locking pins are employed. In the other embodiment the
core is formed with outstanding ribs which engage the shoulders on
the body to maintain the assembled relation.
The core has two bore sections of different radii with the larger
in that portion within the body. A cap plug having an external
locking flange is fitted into the free end of the smaller bore
section with the flange being received in a groove. A base plug is
removably fitted in the lower end of the larger bore section.
The method of manufacture consists essentially of extruding an
appropriate plastic into a strip of a required cross section,
cutting a block of appropriate length from the strip, initially
machining the outer surface of the block to approximate the contour
of the finished pin, drilling a central passage through the block,
milling the interior of the block from the passage to form the
passage to form the inner cylindrical surface, shoulders and bore
sections and after assembly of the core finishing the outer
contour.
Various other more detailed objects and advantages of the invention
such as arise in connection with carrying out the above noted ideas
in a practical embodiment will in part become apparent and in part
be hereinafter stated as the description of the invention
proceeds.
For a full and more complete understanding of the invention
reference may be had to the following description and accompanying
drawings wherein:
FIG. 1 is a perspective of a bowling pin embodying the present
invention.
FIG. 2 is a vertical section through the pin being taken about on
the plane represented by the line 2--2 of FIG. 1.
FIG. 3 is a horizontal section taken about on the plane represented
by the line 3--3 of FIG. 2.
FIG. 4 is a perspective illustrating the elements of the pin in
exploded relation.
FIG. 5 is a vertical section through a modification.
FIG. 6 is a detailed perspective depicting the elements at the
upper end in exploded relation.
FIG. 7 is a detailed exploded perspective of the lower end.
FIG. 8 is an axial section through another modification.
Before referring to the drawings it is noted that the subject pin
may be made of any of the now known plastics having the required
properties of strength, resilence and machinability. However,
polystyrene may be taken as the preferred material. Also while a
duck pin is illustrated, the invention is applicable to other types
of pins such as ten pins or candle pins.
Referring now to the drawings, and first more particularly to FIGS.
1 to 4 inclusive, the bowling pin of this invention is shown as
comprising a body identified in its entirety as B and a core
designated generally at C. Body B has an outer contour of a
curvature corresponding to that of a conventional pin. The outer
surface is designated 10 and terminates at an upper edge 11 and a
lower edge 12. Extending inwardly from edge 11 is an upper bore
section 13 (FIG. 2) which terminates in a shoulder 14.
Extending inwardly from edge 12 is a lower bore section 15
terminating in a shoulder 16. Between shoulders 14 and 16 is a
cylindrical surface 17. Entering body B from bore section 13 is a
closed end recess or socket 18. Diametrically opposed and in
alignment with socket 18 is a passage 19 that extends from outer
surface 10 to bore section 13. Spaced inwardly from lower edge 12
are two passages 20 in alignment. Each passage 20 extends from
surface 10 to bore section 15.
Core C has an outer contour comprising a convex surface 21 and a
concave surface 22 at its upper end. These surfaces 21 and 22 have
a curvature that imparts a contour to the upper portion of the core
similar to that of the corresponding part of a conventional
pin.
Joining concave surface 22 at its lower edge is a cylindrical
surface 23 (FIG. 4) of a diameter near enough to that of bore
section 13 to provide a close fit therewithin when the core C is
assembled in body B. Cylindrical surface 23 terminates at a conical
surface 24 (FIG. 2). Extending below conical surface 24 is a
cylindrical surface 25 that stops at a lower conical surface 26.
From the latter a cylindrical surface 27 extends to a conical
surface 28 at the end of core C.
Core C is hollow with the hollow structure being provided by an
upper bore 29 into which opens a groove 30. Bore 29 extends
inwardly to a conical seat 31. From the wide end of the latter a
lower bore 32 extends to the lower end of core C as defined by a
flat ring like surface 33.
That portion of core C encompassed by cylindrical surface 23 is
formed with two aligned passages 34 which also align with socket 18
and passage 19 when core C is assembled with body B. A locking pin
35 passes through these aligned passages and enters into
maintaining the assembled relation. That portion of core C defined
by cylindrical surface 27 is also formed with aligned passages 36
which also align passages 20. A locking pin 37 passes through these
passages and complete the means for maintaining core C assembled in
Body B.
A cap plug 38, preferably of nylon, has an external flange 39 at
its lower end and this plug is received in the upper end of bore 29
with flange 39 seating in groove 30 to maintain the assembled
relation. Plug 38 is removable and replaceable. A base plug, also
of nylon, comprises a tubular portion 40 and a conical end portion
41 separated from tubular portion 40 by a flat shoulder 42. Tubular
portion 41 is formed with aligned passages 43 which also align with
passages 20 and 36 and pin 37 passes therethrough to maintain the
base plug assembled with the core and body.
End portion 41 of the base plug has a recess 44 in its lower flat
bore which is conventional.
It is notable that cylindrical surface 17 and shoulders 14 and 16
of body B, together with cylindrical surface 25 of core C define an
empty space or chamber 45 that functions much in the manner of a
sound box in determining the sound generated by a ball striking the
pin, and pins engaging each other and alley equipment.
In the manufacture of the pin above described, the plastic
(polystyrene) is extruded into a strip of appropriate cross
section. A block of a length corresponding to body C is cut from
this strip. This block is machined to achieve an outer contour
approximately that of surface 10. It is then drilled to form a
central passage which ultimately provides bore sections 13 and 15.
It is then milled internally from this passage to form shoulders 14
and 16 and inner cylindrical surface 17. Socket 18 and passages 19
and 20 are then formed by drilling.
Core C is preferably also formed from an extruded strip with a
block of proper length being cut therefrom. Outer surfaces 21 and
22 are then rought finished after which the block is drilled from
its opposite ends to form bores 29 and 32. Shoulder 24 and 26
cylindrical surface 25 are then formed by milling. Passages 34 and
36 are then drilled.
Cap plug 38 and the base plug are extruded and finished. After the
parts are assembled as above described all of the outer surfaces
are finally finished. This finishing also enters into accurately
achieving the standard weight.
Referring now to FIGS. 5, 6 and 7 a modified form of invention will
be described. Body B' of FIG. 5 is substantially the same as body B
with the exception of the omission of the passages which receive
the locking pins. There are, however, some important distinctions
between core C of FIGS. 1 to 4 and core C' of FIG. 5.
Core C' has the same upper bore 29 terminating in shoulder 31 of
core C. However, throughout the extent of lower bore 32 core C' is
of uniform wall thickness with the exception of a lower external
rib 46 which presents a shoulder 47 that is in abutting engagement
with shoulder 16 of body B'. Core C" also has an upper rib 48
defined by a conical surface 49 of small pitch and an upper flat
shoulder 50 which engages shoulder 14 of body B' after
assembly.
In assembling core C' with body B' the core is inserted from the
top in the usual way. Due to the hollow construction of the core
and the elastic and resilient nature of the plastic form which it
is made ribs 46 and 48 will ride past bore section 13. At the time
shoulder 16 and 47 abut shoulder 50 is disposed opposite to
shoulder 14 and will snap out into the expanded holding position
illustrated in FIG. 5.
Considering FIG. 6 along with FIG. 5 it will be noted groove 51 in
core C' has a sharp or abrupt upper shoulder 52. Flange 53 in cap
plug 54 has lower conical surface 55 and an upper flat ring like
shoulder 56. As the plug 54 is inserted conical surface 55 aids in
flange 53 riding down bore 29 until shoulder 56 comes opposite to
shoulder 52. Flange 53 then expands into groove 51 to achieve its
holding position.
FIG. 5 shows the lower end of core C' formed with a groove 57
opening into bore 32. As depicted in FIG. 7, a base plug includes a
tubular portion 58 which before complete assembly has an
uninterrupted outer cylindrical contour. It also is formed with a
smooth bore 60.
Bore 60 terminates in a lower flared end 61. A locking plug 62,
which like plug 58 is of nylon, has an external flange 63.
In assembly base plug 58 is first inserted into bore 32. Locking
plug 62 is now inserted in bore 60. Flange 63 will ride along bore
60 until it comes opposite to the groove 57. Due to the flexible
and yieldable properties of the nylon from which plug 58 is made,
and the more solid construction of the locking plug 62, flange 63
will distort plug 58 to force a portion thereof into groove 57 and
thus form retaining flange 59 as shown in FIG. 5.
As an alternative this flange 59 may be initially formed on base
plug 58 and a groove there opposite opening into bore 60.
Base B' and core C' may be manufactured in the same way as as
described in conjunction with base B and core C with the exception
that the transverse passages are not drilled.
In modification of FIG. 8, the body B2 is, in nearly all respects,
the same as body B of FIG. 1 to 4 inclusive with the only
difference residing in a groove 65 that is milled in the bore
13.
Core C2 is also generally similar to core C with the difference
between the two resulting from terminating the core C2 ahort of the
sound box. Thus cylindrical portion 66 is formed with an external
flange 67 at its lower end and this flange 67 is received in groove
65 with a snap fit.
While preferred specific embodiments of the invention are
hereinbefore set forth, it is to be clearly understood that the
invention, is not to be limited to the exact construction,
materials and steps illustrated and described because various
modifications of these details may be provided in putting the
invention into practice.
* * * * *