Abstract:
A bowling ball is disclosed with a core having low density roll blocks or end caps which lowers the differential radius of gyration and lowers the maximum radius of gyration of the ball in order to create a different ball path from the foul line to the pins. When the bowling ball core of the present invention is used within a bowling ball it results in a bowling ball that rolls earlier on the lane for a smooth, curving ball path and less angle change in the backend of the lane.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    Applicant&#39;s invention relates to a bowling ball. More particularly, the present invention relates to a bowling ball with a core having low density roll blocks or end caps which lower both the differential radius of gyration and the radius of gyration. The bowling ball core having the low density roll blocks allows the bowling ball of the present invention to roll earlier than traditional bowling balls for better performance on an oily lane condition.  
           [0003]    2. Background Information  
           [0004]    It is well known in bowling that the shape and density of the core inside the bowling ball will affect the path of the ball as it travels down the bowling lane. Balls are designed to have different ball paths in order to get a proper match between the ball and the oiling pattern on the lane to achieve optimum scoring. The oiling pattern makes the ball reaction different depending on how much oil is applied to the lane and where it is applied to the lane. The goal of the bowler is then to select the proper ball that will result in a margin for error that will allow him or her to miss the target and still get the ball to end up striking. Therefore, some bowling balls are made to hook a small amount and others are designed to hook a lot. Some balls hook early and others travel further down the lane before they start to hook. Once the ball starts to hook, some make a gradual curving motion while others hook sharply. The dynamics of the cores have a large influence on the performance of the ball on the lane.  
           [0005]    It is well known in bowling that a ball with a low radius of gyration (Rg) will get into an earlier roll on an oily lane condition than a ball with a high radius of gyration. The American Bowling Congress (ABC) and Women&#39;s International Bowling Congress (WIBC), the governing bodies for bowling, have set limitations for the radius of gyration to limit the influence of this property. The limits on the radius of gyration are from 2.430 inches to 2.800 inches. Additionally, the differential radius of gyration affects the path of the ball down the lane. The differential radius of gyration is defined in bowling as the difference between the radius of gyration about the minimum principle axis of rotation and the radius of gyration about the maximum principle axis of rotation. The ABC and WIBC also have a specification to control the differential radius of gyration. This specification limits the differential radius of gyration to a maximum of 0.080 inches.  
           [0006]    A ball with a high differential Rg will migrate to the preferred spin axis of the core at a fast rate as it travels down the lane. This high differential Rg will change the contact area of the ball with the lane and cause the track on the ball to separate, or flare. This will allow an area of the ball that has not touched the lane, and thus picked up oil, to touch the lane. A dry surface of the ball will create more friction with the lane surface to create more hooking action or to increase the sharpness of the hooking action. Therefore, all modern high performance balls are designed taking into account the Rg and differential Rg to achieve different frictions to alter the ball path. Many existing bowling balls are designed with end caps, often called flip blocks. The flip blocks are added to the top of the core, the bottom of the core, sides of the core, or in various combinations. The flip blocks are typically equal or more dense than the coverstock. By having these dense flip blocks located away from the center of the ball, the differential radius of gyration is increased. The increased differential radius of gyration causes a sharper hooking action, also called flipping in bowling. They can also be added to make it easier to hit a specific differential Rg value by manipulating the densities of the various components.  
           [0007]    The present invention has a main core body with a design shape that creates a high differential radius of gyration. Shapes, such as, but not limited to, a long cylinder or hourglass can be made from dense materials which will create the high differential radius of gyration for the main core body. Added on the top of the core, bottom of the core, or both are low density end cap(s) of any shape designed to reduce the differential radius of gyration. With this invention it is possible to optionally design a core body in a bowling ball shell with a differential radius of gyration greater than the ABC and WIBC specification would allow and then add the low density end caps to reduce the differential Rg to within the allowable specification. The addition of low density end caps near the surface of the ball also has the advantage of lowering the maximum radius of gyration of the ball.  
           [0008]    The addition of low density end caps, or flip blocks, in the present invention has the opposite effect of high density flip blocks. High density flip blocks are added to create a ball path with a sharp turn at the end of the oiled area of the lane. These high density flip blocks generally have a density that exceeds 2.5 g/ml. In contrast, low density end caps will make the ball want to hook sooner in the oil with less angle change on the backend of the lane. This creates more of an arcing or rolling ball path. Therefore, a preferred name for the end caps of the present invention would be roll blocks. Normally this reaction works well on a lane condition with a heavy concentration of oil.  
           [0009]    Some related patents are known in the art; however, the present invention is clearly distinguishable. The prior art uses heavy flip blocks to raise the differential radius of gyration to create more hook and strong reaction on the backend of the lane. The present invention concentrates more weight in the core body and lowers the differential radius of gyration with flip blocks having light weight materials and shapes located close to the ball surface. This results in an earlier hooking motion with less reaction on the backend of the lane which is particularly beneficial for use of the ball on a heavily oiled lane condition. In U.S. Pat. No. 6,027,412 issued to Pinel et al. on Feb. 22, 2000 a bowling ball with an inner weight block is disclosed. This patent concerns a core shape comprised of a body with a head and a tip. It specifically states that the head and tip each has a density greater than the shell. This patent is for an offset of the core body from the x-axis to create a sharp hook further into the roll. In contrast in the present invention, the end caps have a density which is less than the shell to make a ball that hooks earlier with a reduction in the sharpness of the hook.  
           [0010]    U.S. Pat. No. 4,353,850 issued to MacDonald on Oct. 12, 1982 discloses a method of making a bowling ball. In this patent there is mention of a lightweight member in a bowling ball with a heavy member on the opposite side. The lightweight member is located 3 to 6½ inches from the shell with the purpose of changing the impact with the pins. In contrast in the present invention, the outer edge of the low density roll blocks must be located from ¼ to 1½ inches from the outer surface of the ball to lower the radius of gyration. The purpose of this present invention is to alter the ball path to the pins.  
           [0011]    Additional patents include U.S. Pat. No. 3,350,252 issued to Twickler on Oct. 31, 1967 which discloses a structure and manufacture of bowling balls. The invention of that patent provides a top weight by including in the core of a bowling ball a foam plastic insert spaced radially outward from the center of the external shell in the bottom of the ball. In U.S. Pat. No. 3,256,018 issued to Baggenstoss on Jun. 14, 1966 a bowling ball and process of making is disclosed. In this patent a bowling ball is disclosed having a shell enclosed hollow sphere with the inner wall concentric with the outer surface of the ball. The present invention clearly contrasts with these designs.  
         SUMMARY OF THE INVENTION  
         [0012]    It is an object of the present invention to provide a novel bowling ball that utilizes a core that can alter the bowling ball&#39;s path to the pins.  
           [0013]    Another object of the present invention is to provide a novel bowling ball that utilizes a core that allows the bowling ball to create an earlier curving motion on the lane.  
           [0014]    Still another object of the present invention is to provide a novel bowling ball that utilizes a core having a core body with a differential radius of gyration that may be greater than ABC/WIBC limits and then make it legal with low density end caps.  
           [0015]    Yet another object of the present invention is to provide a novel bowling ball that utilizes a core that lowers the radius of gyration of the bowling ball with low density end caps located with their outer surface from ¼ to 1½ inches from the outer surface of the bowling ball.  
           [0016]    It is another object of the present invention to provide a novel bowling ball that utilizes a core that can be used in the bowling ball to make the ball better suited for an oily lane condition.  
           [0017]    In satisfaction of these and related objectives, Applicant&#39;s present invention provides for a bowling ball with a core having low density end caps which lowers the differential radius of gyration and lowers the maximum radius of gyration in order to create a different ball path from the foul line to the pins. The use of this core having low density roll blocks within the present bowling ball results in a bowling ball that rolls earlier on the lane for more hook.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a cross section of the preferred embodiment of the present invention utilizing a round core.  
         [0019]    [0019]FIG. 2 is a cross section of the preferred embodiment of the present invention not utilizing a round core. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    This invention relates to a bowling ball and more specifically to a high performance bowling ball. Because a bowling ball must be of a certain diameter, hardness, and coefficient of restitution to satisfy the requirements of the American Bowling Congress (ABC) and must also have the capacity to withstand repeated inertial shocks without cracking, fracturing, or denting, bowling balls are typically designed to be solid throughout. Compliance with the ABC/WIBC Equipment Specifications Manual (hereinafter “ABC Specifications”) is of vital commercial importance because only complying bowling balls may be used in the majority of bowling tournaments held in the United States.  
         [0021]    Current ABC/WIBC Specifications provide that a bowling ball shall be constructed without voids in its interior, be of a nonmetallic composition, have a circumference of no more than 27 inches and a weight no more than 16 pounds. The diameter of the ball must be constant, and is typically 8.590 inches. The surface hardness must be no less than 72 Durometer (D). The minimum Rg can be no lower than 2.430 inches and the maximum Rg can be no greater than 2.800 inches.  
         [0022]    The bowling ball having the core of the present invention rolls earlier than traditional bowling balls for better performance on an oily lane condition. It will be understood by those of ordinary skill in the art that known types of bowling ball manufacturing equipment are used in manufacturing the present invention. Bowling balls containing an inner core and an outer shell are known in the prior art and such known manufacturing techniques are partially used in the present invention. In addition, it will be understood that the present invention can be applied to any typical bowling ball utilizing conventional materials. Such conventional shell materials may include polyester, polyurethane, vinylester, and epoxy. One or more inner cores or outer shells of the same or varying composition may be used within the bowling ball and provided for in the manner shown below for a bowling ball having a single inner core and a single outer shell or layer.  
         [0023]    The inner core may be of various shapes. The inner core composition may contain such materials as barium sulfate (BaSO 4 ), hematite (Fe 2 O 3 ), calcium carbonate (CaCO 3 ), bismuth (Bi), glass and plastic microspheres, and graded fly ash, while the outer shell may contain materials such as epoxy, polyurethane, polyester, plasticizers, and inorganic particles in any conventional amounts. The bowling ball of the present invention and any bowling ball core used within it will be composed of the above mentioned materials as well as any additional industry adopted materials in various percentages to achieve the desired final densities. The term “outer layer” as used herein refers to the portion of the bowling ball at or near the ball&#39;s outer surface.  
         [0024]    Referring to FIG. 1, a cross section of the preferred embodiment of the present invention utilizing a round core  101  is shown. The bowling ball  100  has an outer layer or shell  102 , a round outer core  101  and an inner core body  103 . Inner core body  103  can create a high or low Rg with a high differential radius of gyration preferably in excess of 0.050 before the addition of the low density end cap or caps  104 . Inner core body  103  is highly dense, preferably having a density in excess of 2.25 g/ml; however, this may vary depending on the desired Rg and differential Rg values. Shapes for inner core body  103 , such as, but not limited to, a long cylinder or hourglass can be made from dense materials, such as but not limited to barium sulfate, hematite, calcium carbonate, and bismuth, which will create the high differential radius of gyration.  
         [0025]    Added on the top and/or bottom of inner core body  103 , is at least one low density end cap  104  of any shape designed to reduce the differential radius of gyration. The end caps  104  can be made from any material or combination of materials used in the bowling industry. However, it is preferred that end caps  104  of the present invention have a density below 1.1 g/ml. The low density end cap  104  is preferably placed toward the ends of the length of inner core body  103 . The addition of at least one low density end cap  104  near the surface of the ball  100  also has the advantage of lowering the maximum radius of gyration of the ball  100 . For the preferred embodiment of the present invention, the outer edge of the end caps  104  must be located from ¼ to 1½ inches from the outer surface of ball  100  to lower the radius of gyration. Low density end caps  104  make ball  100  hook sooner in the oil with less angle change on the back end of the lane. This creates more of a rolling path for ball  100 . The location of the hook and entry angles vary and are dependent on the location of the oil on the lane and the rotation generated by the individual bowler. This invention works well with lane conditions that have a heavy concentration of oil.  
         [0026]    Pin  105  penetrates through bowling ball  100  into any end cap  104  that may be present at its general location and into inner core body  103 . The pin  105  is used to position the inner core body  103  and end caps  104  in the desired location within the bowling ball  100 . Pin  105  is typically indicated as a small circle of a different color found on the surface of bowling ball  100 . It locates the minimum principle moment of inertia axis of the ball. In the final ball drilled with gripping holes (not shown) for the bowler&#39;s fingers, the placement of pin  105  relative to the gripping holes will affect the ball dynamics as known by those skilled in the art. After the ball  100  is built, the ball  100  is removed from the mold leaving a void where the pin  105  was. The void is filled with any material or combination of materials used by those in the industry.  
         [0027]    The outer layer or shell  102  surrounds the inner core body  103  and any end caps  104  that may be attached to the inner core body  103 . Outer layer or shell  102  is more dense than the end caps  104 , preferably having a density ranging from 0.9 g/ml to 1.3 g/ml.  
         [0028]    The following data illustrate bowling balls that satisfy the requirements for the present invention and are provided by way of example. A 16 pound bowling ball was developed having a low Rg value of approximately 2.509 inches, a high Rg value of 2.549 inches, and a differential Rg value of 0.040 inches. Inner core body  103  was designed with a density of approximately 2.85 g/ml and outer core  101  was designed with a density of approximately 1.10 g/ml. Two end caps were used-one having a density of approximately 0.90 g/ml and one having a density of approximately 0.80 g/ml.  
         [0029]    The present invention can also be designed without a round outer core  101 . FIG. 2 illustrates a cross section of the preferred embodiment of the present invention not utilizing a round outer core  101 .  
         [0030]    The following data illustrate bowling balls not having the round outer core  101  that satisfy the requirements of the present invention and are provided by way of example. A 16 pound bowling ball was developed by having a low Rg value of approximately 2.506 inches, a high Rg value of approximately 2.551 inches, and a differential Rg value of 0.045 inches. Inner core  103  was designed with a density of approximately 2.78 g/ml. No outer core was used. Two end caps were used-one with a density of approximately 0.90 g/ml and one with a density of approximately 0.70 g/ml.  
         [0031]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.