Bowling ball

A bowling ball wherein the weights of the inner core and the encapsulating mass are varied through the use of materials of preselected densities, for the purpose of manufacturing balls having a low moment of inertia. The instant invention accomplishes this by featuring an inner core having a minimum specific gravity of 0.1063 per pound of ball weight, and a construction wherein the volume ratio of the inner core to that of the encapsulating mass, in conjunction with the specific gravity ratio of the inner core to that of the encapsulating mass, yields a maximum moment of inertia (about the ball's vertical axis) of 0.318 in-ozs-sec.sup.2 per pound of ball weight. As the moment of inertia of a fixed weight ball is decreased, the translational kinetic energy increases and the rotational kinetic energy decreases. However, since the translational kinetic energy increases at a greater rate than the rate at which the rotational kinetic energy decreases, the resulting effect is an increase in total kinetic energy output. An additional increase in total kinetic energy output is obtained through use of a high density top weight mass concentrated closely around the ball's inner core, with its lower surface positioned at the midplane of the ball.

BACKGROUND OF THE INVENTION 
This invention relates to game bowling balls having a minimum weight of 8 
pounds. 
Regulation game bowling balls are made to American Bowling Congress 
specifications which state in part that bowling balls shall be constructed 
of a non-metallic composition material, having a maximum circumference of 
27.002 inches, a minimum circumference of 26.704 inches, and a minimum 
ball surface hardness of 72 Shore D durometer. Also, the top portion of 
the ball shall not be more than 3 ounces greater than the bottom portion 
for balls 10 pounds or more, and the top portion of the ball shall not be 
more than 1 ounce greater than the bottom portion for balls less than 10 
pounds, after finger and thumb hole drilling. 
Most presently manufactured bowling balls are made of uniform density 
material throughout, or with a rubber or resin cover material 
encapsulating a conventional inner core, thereby providing a bowling ball 
having less than optimum total kinetic energy output. It is an 
advantageous feature of this invention to relocate an outer portion of the 
ball's weight toward the center. This weight distribution provides for a 
lower moment of inertia, a feature that is desirable when greater total 
kinetic energy output is desired. Greater total kinetic energy output will 
operate to provide more ball hooking action, and more ball drive and 
mixing action when hitting the pins, than is obtainable with presently 
available bowling balls. Also, instead of locating the top weight mass 
toward the surface of the ball as disclosed by Luth et al. (U.S. Pat. No. 
2,291,738), Satchell (U.S. Pat. No. 3,068,007), and Sauer (U.S. Pat. No. 
2,414,672), this invention offers an option by locating the top weight 
mass as close as possible around the high density inner core. 
SUMMARY OF THE INVENTION 
The intent of this invention is to provide a bowling ball having greater 
total kinetic energy output, by constructing the ball such that the 
combination of translational and rotational kinetic energies are greater 
than those of presently available balls. The increase in total kinetic 
energy is accomplished by decreasing the moment of inertia of a 
predetermined weight ball so that it can provide a greater output of work. 
It is to be noted that as the moment of inertia of a fixed weight ball is 
decreased, the translational kinetic energy increases and the rotational 
kinetic energy decreases. However, the translational kinetic energy 
increases at a greater rate than the rate at which the rotational kinetic 
energy decreases, thus resulting in an increase in total kinetic energy. 
As the moment of inertia of a fixed weight ball is decreased, the distance 
the ball travels decreases before pure uniform rolling motion impends 
(ball skidding with rolling action ceases), and the total kinetic energy 
output of the ball increases. This means that a fixed weight ball of lower 
moment of inertia will start pure rolling action sooner and possess 
greater total kinetic energy at the instant pure rolling commences. As a 
result the ball will track sooner for better bowler control, to provide 
increased hooking action with increased total kinetic energy when hitting 
the pins. 
For example, through theoretical analysis, a presently available prior art 
16 pound ball having a calculated moment of inertia of about 0.0255 
ft-lbs-sec.sup.2, will when thrown with an initial linear velocity of 
about 30'/sec and an initial angular velocity of about 12 Rad./sec, will 
provide a calculated total kinetic energy output of about 179 ft-lbs. A 16 
pound ball constructed to the instant invention with a calculated moment 
of inertia of about 0.0165 ft-lbs-sec.sup.2 will when thrown with an 
initial velocity of about 30'/sec and an initial angular velocity of about 
12 Rad./sec, will provide a calculated total kinetic energy output of 
about 191 ft-lbs. 
In order for a bowler to throw a ball with sufficient total kinetic energy 
to provide for proper pin action, the initial velocity with which the said 
ball is delivered should be maintained at about 30'/sec with a 16 pound 
ball. For example, if a bowler throws the above cited presently available 
0.0255 ft-lbs-sec.sup.2 moment of inertia 16 pound prior art ball with an 
initial linear velocity of about 25'/sec and an initial angular velocity 
of about 12 Rad/sec, the calculated total kinetic energy output would be 
only about 127 ft-lbs. However, if in order to obtain more velocity on the 
ball, the bowler selects a presently available 0.022 ft-lbs-sec.sup.2 
moment of inertia 14 pound ball and delivers it with an initial linear 
velocity of about 30'/sec and an initial angular velocity of about 12 
Rad/sec, said delivered ball would provide about 156 ft-lbs of calculated 
kinetic energy. If instead, the bowler used a 14 pound ball of the instant 
invention having a calculated moment of inertia of about 0.0139 
ft-lbs-sec.sup.2, and delivers it with an initial linear velocity of about 
30' /sec and an initial angular velocity of about 12 Rad/sec, said ball 
would provide a calculated total kinetic energy of about 168 ft-lbs, 
compared with the above cited 156 ft-lbs for a 14 pound presently 
available ball. All of above cited values for total kinetic energy output 
of the instant invention were obtained from consideration of a bowling 
ball structural arrangement consisting only of a high density inner core 
in conjunction with a molded encapsulating mass. Also, a 3 inch diameter 
sintered tungsten carbide inner core and a one half inch thick 
polyurethane resin cover, were used for above cited 16 and 14 pound balls 
of the instant invention. 
Ball moment of inertia in the instant invention is decreased when compared 
to a presently available bowling ball of equal weight, by design-wise 
removing weight from the outer portion of said prior art ball and by 
various means design-wise redistributing said removed weight to the 
innermost portion of the ball. Therefore, it is apparent that the main 
intent of this invention is to provide a high density inner core type 
bowling ball that has substantially improved operating characteristics. 
Accordingly objects of this invention are as follows: 
To reduce, or possibly eliminate, the disadvantage experienced by a bowler 
who cannot handle and control a heavy weight ball. 
To provide a ball that will more fully satisfy the demands of bowlers of 
varying skills. 
To provide a ball concept applicable to the manufacture of a variety of 
balls of different weights. 
To provide a ball having greater total output energy than a ball when 
delivered with the same initial linear and angular velocities. 
To provide a ball having approximately the same total output energy as a 
heavier ball of greater moment of inertia. 
To provide a ball that features lower moment of inertia to provide greater 
total output energy. 
To provide a ball having better ability to mix the pins with less ball 
deflection within a slippery pin deck area, due to the greater 
availability of total output energy when compared to a prior art ball. 
To provide a ball that will track sooner for the purpose of providing 
proper hooking action on a fast lane where balls do not hook readily. 
To provide a ball that can be used to develop additional hooking action not 
initially imparted by the bowler. 
To provide a ball with substantially increased total energy output for the 
purpose of providing effective ball drive and mixing action upon hitting 
the pocket to knock over pins. 
To provide a ball that can be manufactured to American Bowling Congress 
specifications.

Terms herein utilized should bear interpretation such as follows: 
Inner Core--It is defined as the innermost mass that is surrounded by the 
molded encapsulating mass, which may or may not integrally include top 
weight mass. 
Inner Core Density or Specific Gravity--It represents the value obtained 
when dividing the total weight (in grams) of the inner core, by the total 
volume (in cubic centimeters) of the inner core. 
True Particle Density--This density corresponds to the weight of an average 
particle divided by its real volume. 
Ball's Vertical Axis--It is defined as an axis running through the ball 
between its top and bottom. The top of the ball being that portion which 
contains the top weight mass. 
Bowling Ball--It refers to any presently available game bowling ball. 
Moment of Inertia--It is defined as the sum of the product of the mass of 
each particle in a rigid body and the square of its distance from a common 
axis, or the ratio of the resultant external torque to the angular 
acceleration with respect to said axis. 
Translational Kinetic Energy--It is equal to one-half the body mass, times 
the square of body velocity. 
Rotational Kinetic Energy--It is equal to one-half the moment of inertia of 
the body about its center of rotation, times the square of the body's 
angular velocity. 
Total Kinetic Energy--It is the summation of translational and rotational 
kinetic energy. 
Calculated Moment of Inertia--It represents the moment of inertia obtained 
through calculations based on equations which are well known in the art. 
Calculated Total Kinetic Energy--It represents the total kinetic energy 
obtained through calculations based on equations which are well known in 
the art. 
Syntactic Foam--It is defined as a lightweight material consisting of 
hollow spheres of either phenolic, epoxy, ceramic, or glass, dispersed in 
rubber or within a thermosetting resin such as epoxy, polyester, 
polyurethane, etc. 
DESCRIPTION OF THE INVENTION 
Generally, the bowling balls illustrated in FIGS. 1 and 2, and described 
herein as two embodiments of the instant invention, preferably comprise a 
spherical high density solid inner core having its center substantially 
coincident with the ball's geometrical center; a molded encapsulating mass 
surrounding said inner core, which exists as a cover in the FIG. 1 
embodiment, and as an outer core and cover in the FIG. 2 embodiment; and 
an annular top weight mass located within the molded encapsulating mass 
and disposed closely around the high density inner core with its lower 
surface located at the midplane of the inner core. Said encapsulating mass 
being characterized as including one or more spherical shells. It should 
be noted that the annular top weight mass, which is used to offset the 
loss of weight resulting from drilling the thumb and finger holes, and 
also if desired to provide for the maximum ABC allowable 3 ounce 
out-of-balance permitted between the top and bottom of balls 10 pounds or 
more, is placed as close to the inner core as possible in order to assist 
toward further decreasing the moment of inertia of the ball over and above 
the reduction obtained through use of the high density spherical inner 
core alone. The annular top weight mass may be manufactured integral with 
the inner core, or as a separate piece closely positioned around the inner 
core. It should be further noted that bowling balls of this invention can 
be manufactured to include either the presently used conventional top 
weight blocks, or the novel high density annular top weight mass herein 
disclosed. The size and density of the inner core is selected as a 
function of the amount of total kinetic energy output desired for a ball 
of predetermined weight, and the density of the top weight mass is 
selected as a function of the amount of further decrease in moment of 
inertia desired over and above that provided solely by the utilization of 
a high density inner core. The denser the annular top weight mass 
surrounding the inner spherical core and concentrated close to the 
midplane of the ball, the greater will be the reduction in ball moment of 
inertia. Also, the denser the material used for the inner core, resulting 
from relocating weight removed from the outer portion of a ball, the 
greater the reduction in ball moment of inertia. 
Referring to FIG. 1 of the drawing, one embodiment of this invention will 
include a spherical inner core 2 made from inorganic compounds including 
such bonded powdered ceramics as tungsten carbide, thoria, zirconia, 
alumina, or bonded powdered minerals such as copper oxide, lead oxide, 
zinc oxide, etc. Also, the annular top weight mass 3 can be made from the 
same bonded ceramic or mineral materials as used for the inner core. 
During ball manufacture, inner core 2 with integrally attached annular top 
weight mass 3 are supported within the spherical cavity of a two section 
split mold by a support pin such as disclosed in Randolph (U.S. Pat. No. 
4,131,277). Cover 1 is formed when a liquid casting resin is poured to 
fill the mold cavity around inner core 2 and top weight mass 3. Cover 1 
can be made from rubber and such thermosetting resins as filled, unfilled, 
modified, or unmodified polyurethane, polyester, alkyd, acrylic, epoxy, 
etc. Filled rubber resins include high density powdered materials such as 
barium sulfate, iron oxide zinc oxide, or lead oxide, and low density 
syntactic foams having hollow spheres of either epoxy, phenolic, ceramic, 
or glass embedded within the base material. Modified resins include 
another resin or elastomer mixed with the base resin. For example, epoxy 
mixed with the polyurethane base resin. After the ball is removed from the 
mold, the hole produced by the support pin is filled with a resin 
equivalent in density to that of cover 1. The ball is then ready for 
finishing to the prescribed diameter approved by the ABC. It should be 
noted that spherical inner core 2 and annular top weight mass 3 
manufactured by means of the sintering process well known in the ceramic 
art. Also, they can be formed by cold pressing a mixture of such bonding 
resins as epoxy, polyester phenolic, polyurethane, etc. with any of the 
powdered or grained ceramics or minerals cited, and allowing the resin 
binder to set. It should be noted that the true particle density of 
tungsten carbide is about 12 to 16 gm/cc, that of thoria is about 10.5 
gm/cc, that of zirconia is about 6.1 gm/cc, that of alumina is about 3.4 
to 3.9 gm/cc, that of copper oxide is about 6.0 gm/cc, that of lead oxide 
is about 9.3 to 9.7 gm/cc, and that of zinc oxide is about 5.6 gm/cc. It 
should be noted that the densities of sintered materials are substantially 
equal to the above cited true particle densities, whereas the densities of 
resin bonded ceramics or minerals are substantially less than the above 
cited true particle densities. For example, resin bonded alumina can be 
readily molded to composition densities from about 1.7 gm/cc to about 2.2 
gm/cc, resin bonded barium sulfate can be readily molded to densities from 
about 1.7 gm/cc to about 3.2 gm/cc, resin bonded iron oxide can be readily 
molded to densities from about 1.7 gm/cc to about 3.4 gm/cc, resin bonded 
zinc oxide can be readily molded to densities from about 1.7 gm/cc to 
about 3.6 gm/cc, and resin bonded lead oxide can be readily molded to 
densities from 1.7 gm/cc to about 6.2 gm/cc. Based on above cited 
composition densities, inner cores can be molded having density values of 
1.7 gm/cc or larger. To obtain the claimed minimum inner core specific 
gravity per pound of ball weight, 1.7 is divided by the ball weight of 16 
pounds, to yield a value of 0.1063. It should be obviously noted that 
balls can also be made having inner core specific gravity values per pound 
of ball weight greater than the above cited 0.1063. Also, the density of 
hard rubber such as ebonite is about 1.15 gm/cc, that of polyurethane 
resin is about 1.04 to 1.40 gm/cc, that of polyester resin is about 1.05 
to 1.46 gm/cc, that of alkyd resin is about 1.9 to 2.3 gm/cc, that of 
acrylic resin is about 1.08 to 1.20 gm/cc, and that of epoxy resin is 
about 1.1 to 1.4 gm/cc. 
Syntactic foams can range in density from about 0.38 to 1.0 gm/cc, 
depending on the amount of lightweight filler added to the rubber or resin 
base material. 
Referring to FIG. 2 of the drawing, the second embodiment of this invention 
will include a spherical inner core 6 made from bonded powdered ceramics 
such as tungsten carbide, thoria, zirconia, or alumina, or bonded powdered 
minerals such as copper oxide, lead oxide, or zinc oxide. Also, the 
geometrically shaped annular top weight mass 7 can be made from the same 
bonded ceramics or minerals as the inner core. During ball manufacture, 
spherical inner core 6 with integrally attached annular top weight mass 7 
are supported within the spherical cavity of a two section split mold by a 
support pin such as disclosed in Randolph (U.S. Pat. No. 4,131,277). When 
outer core 5 is made from filled or unfilled casting resins such as 
polyurethane, polyester, alkyd, acrylic, epoxy, etc., the casting resin is 
poured around inner core 6 and top weight mass 7, and allowed to set up. 
After removal from the mold, the core can be finished to a prescribed 
diameter. The filled resins can include low density granular or powdered 
materials such as hollow spheres of various materials, sawdust or cork, 
when a material of lower density than the base resin is desired. To make 
the outer core 5 of a higher density than the base resin, filler materials 
such as barium sulfate, iron oxide zinc oxide, or lead oxide powders may 
be used. Outer core 5 can also be made from molded composition cork, 
bonded sawdust, syntactic foam, rigid polyurethane foam, and rigid 
polyvinyl chloride foam, by manufacturing means well known in the art. The 
density of syntactic foam is about 1.0 gm/cc or less, that of rigid 
polyurethane foam is about 0.016 to 0.96 gm/cc, that of rigid polyvinyl 
chloride foam is about 0.064 to 0.4 gm/cc, and that of composition cork is 
about 0.19 to 0.48 gm/cc. 
Spherical outer core 5, with support pin hole therein, is then placed 
within another spherical split section mold of such diameter as to allow 
for a prescribed cover thickness. The core 5 assembly is held in place 
within the mold by a support pin which engages the support pin hole 
obtained when outer core 5 was cast. Next, cover 4 is formed when a liquid 
casting resin is poured to fill the mold cavity around outer core 5. Cover 
4 can be made from syntactic foam, hard rubber such as ebonite, and such 
resins as modified or unmodified polyurethane, polyester, alkyd, acrylic, 
epoxy, etc., having a minimum Shore D durometer hardness of 72. After the 
cover resin sets up, the mold is opened and the ball removed. The support 
pin hole within outer core 5 of the ball will be filled with a material 
equivalent in density to that of said outer core 5. Also, the support pin 
hole in cover 4 will be filled with a resin equivalent in density to that 
of cover 4. The ball is finally ready for finishing to the prescribed 
diameter approved by the ABC. It should be noted that inner core 6 and 
annular top weight mass 7 are manufactured by means herein previously 
disclosed. 
In bowling balls of the instant invention, the weights of the inner core, 
outer core, and cover may be varied through use of materials of 
preselected densities, for the purpose of manufacturing balls having 
moments of inertia lower than presently available bowling balls. 
The instant invention accomplishes this by featuring an inner core having a 
minimum specific gravity of 0.1063 per pound of ball weight, and a ball 
construction wherein the volume ratio of the inner core to that of the 
encapsulating mass, in conjunction with the specific gravity ratio of the 
inner core to that of the encapsulating mass, yields a maximum moment of 
inertia about the ball's vertical axis of 0.318 in-ozs-sec.sup.2 per pound 
of ball weight. 
In order that this invention may be more fully understood, the following 
illustrative examples are presented: 
EXAMPLE I 
A prior art 16 pound ball having a diameter of 8.58", will have a moment of 
inertia of about 0.02547 ft-lbs-sec.sup.2. Now, a 16 pound ball made to 
the instant invention and having a 4.884" diameter inner core, a 7.08" 
diameter outer core, and an 8.58" cover diameter, will provide a 
calculated moment of inertia of about 0.02072 ft-lbs-sec.sup.2 (0.24864 
in-ozs-sec.sup.2). 
EXAMPLE II 
A prior art 14 pound ball having a diameter of 8.580", will have a moment 
of inertia of about 0.02458 ft-lbs-sec.sup.2. Now, a 14 pound ball made to 
the instant invention and having a 4.469" diameter inner core, a 7.08" 
diameter outer core, and an 8.58" cover diameter, will provide a 
calculated moment of inertia of about 0.01907 ft-lbs-sec.sup.2 (0.26153 
in-ozs-sec.sup.2). 
EXAMPLE III 
A prior art 10 pound ball having a diameter of 8.58", will have a moment of 
inertia of about 0.01999 ft-lbs-sec.sup.2. Now, a 10 pound ball made to 
the instant invention and having a 3.267" diameter inner core, a 7.08" 
diameter outer core, and an 8.58" cover diameter, will provide a 
calculated moment of inertia of about 0.01685 ft-lbs-sec.sup.2 (0.3235 
in-ozs-sec.sup.2). 
In the above cited examples, the inner core has a density of about 0.143 
#/in.sup.3 (3.96 gm/cc), the outer core has a density of about 0.0026 
#/in.sup.3 (0.072 gm/cc), and the cover has a density of about 0.048 
#/in.sup.3 (1.33 gm/cc).