Abstract:
A two-piece bowling ball includes a non-symmetrical weight block or core to provide improved and increased rotation inertia. The block consists of head, body and tip portions. The block is asymmetric in plan, the asymmetry being the result of truncation of a plan-symmetric form of the block by a plane extending through the block at an angle of less than 90 degrees to the vertical, removing less than 50% of the plan-symmetric block mass. The untruncated form of the head is a spherical segment of one base having its spherical surface concentric with the surface of the ball. The non-truncated body is in the form of a cylinder or parallelepiped, while the tip in its untruncated form is of a shape having a maximum diameter no greater than that of the body whose diameter is no greater than that of the head. The tip is further chosen such that overall top eccentricity after truncation does not exceed three ounces in accordance with ABC guidelines.

Description:
The present invention is a continuation-in-part of U.S. patent application Ser .No. 07/690,510, filed Apr. 14, 1991, and relates to an improved bowling ball weight block which exhibits increased &#34;action&#34; while maintaining consistent performance over a range of lane conditions. 
    
    
     BACKGROUND OF THE INVENTION 
     Lane conditions encountered by a bowler vary significantly. In addition to large variations among different lanes due to age, condition and type of surface, the same lane can vary in surface condition over the course of a game or tournament as a result of its usage. The condition and surface of a lane affects the dynamics of ball travel down the lane and accordingly can cause variation in the path of the ball despite efforts of the bowler to maintain a consistent roll. 
     Experienced bowlers can control the trajectory of the ball and accordingly are able to adjust to some degree for different lane conditions. Even with such adjustments, however, variations in the condition and surface of the lane across the width and along the length of the lane still can place inconsistencies and variations in ball travel which are unpredictable and detrimental to the player. Accordingly, it is desirable and advantageous to provide a ball which, to the greatest extent possible, provides a consistent roll, minimizes roll variations due to lane surface conditions, thus maximizing the control of the bowler over the ball and providing predictable, consistent characteristics for ball travel. 
     In application Ser. No. 690,510 a weight block which forms the core of a two-piece bowling ball construction was disclosed which has the effect of providing increased consistency of ball roll over a wide range of lane conditions. 
     That invention utilized an internal weight block of novel design to provide a substantially increased rotational inertia while conforming with guidelines established for bowling balls by the American Bowling Congress and Women&#39;s International Bowling Congress. A bowling ball utilizing the invention provided increased angular momentum to minimize the roll effects of the lane surface while maintaining a weight eccentricity of less than three ounces after drilling when tested according to ABC/WIBC guidelines and maintaining a total ball weight of no more than sixteen pounds. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It has now been discovered that further modification over the rotational characteristics of a ball embodying the invention of Ser. No. 690,510 can be accomplished within ABC/WIBC guidelines by modifying the weight block disclosed therein in accordance with the present invention. By eliminating a portion of the weight block lying beyond a defined plane through the block, either parallel to the vertical axis of the block or at a tilt angle thereto, the centroid of the block and thus the rotating ball is offset from the vertical axis, thus increasing ball &#34;action&#34; and thus providing the skilled bowler with additional ability to adjust ball roll for changing lane conditions. 
     The present invention thus comprises a core formed by a weight block which, for descriptive purposes herein, is defined as comprising adjacent head, body and tip portions, the main axis of the block being oriented substantially along the ball vertical axis. The weight block is characterized by the head being in the form of a generally spherical segment whose surface is approximately concentric with the outside surface of the ball and is positioned one inch or less from the surface of the ball. 
     The body of the weight block is cylindrical or of a regular parallelepiped configuration, of a radius no greater than the radius of the head, and has a length no greater than the diameter of the head, terminating at a point located between the horizontal mid-line of the block and the point corresponding to the head diameter. The body may optionally include an annular ring projecting outwardly over a portion of its surface. 
     The tip terminates the weight block at its lower end and is in a form of an element chosen such that the total weight of the block lying below the horizontal axis of the ball is less than the portion of the block above the mid-line. The maximum radius of the tip is no greater than that of the body. 
     A plane bisects the weight block, the portion of the weight block extending beyond the plane (i.e., on the side of the plane away from the vertical axis of the block) being removed to form an imbalanced mass with respect to the vertical axis of the block. The plane may be oriented parallel to the vertical axis of the block, removing a portion no greater than half the block, or may be at an angle of less than 90 degrees from the vertical. The truncated block, when embodied in a ball as a core therefor, is dimensioned and weighted such that the overall top weight eccentricity of the ball after drilling is not to exceed 3 ounces as measured in accordance with ABC guidelines, while the radii of gyration about the vertical and horizontal axes are between 2.80 and 2.43 inches, with no greater than a 0.08 inch differential. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A fuller understanding of the present invention will be achieved upon consideration of the following detailed description of preferred, but nonetheless illustrative embodiments of the present invention when taken in association with the annexed drawings, wherein: 
     FIG. 1 is an elevational cross-sectional view of a first embodiment of a weight block of the present invention shown in position within a bowling ball in which the removed weight block portion is defined by a vertical plane. 
     FIG. 2 is an elevational cross-sectional view of the embodiment of FIG. 1 incorporating an annular ring about the body; 
     FIG. 2A is an elevational view of the embodiment of FIG. 2 in which the removed block portion is defined by a plane through the lower half of the block at a 45 degree angle to the vertical axis; 
     FIG. 2B is an elevational view of the embodiment of FIG. 2 in which the removed block portion is defined by a plane through the upper half of the block at a 30-degree angle to the vertical axis; 
     FIG. 3 is a sectional plan view looking upward from line 3--3 in FIG. 1, taken along a line parallel to and just below the intersection of the body and head portion, depicting an alternative shape for the body; 
     FIGS. 4A and 4B are illustrative alternate forms for the annular ring, in cross-section; 
     FIG. 5 is a cross-sectional view of an embodiment having an enlarged tip; and 
     FIGS. 6-8 represent other alternative embodiments in cross-section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As seen initially in FIG. 1, the weight block of the present invention from which the core is formed, has a head portion 10, a body portion 12, and a tip portion 14, typically formed out of a mass of one or more appropriate compounds, typically polyesters or urethanes, compounded and combined as known in the art to an appropriate overall density to allow the combination of the core and the shell 16 of the ball to fall within the 16-pound limit. Typically the weight block is of a greater total density than the shell, although the density of the portions of the block may be variable, controlled by the compounds utilized for the block and their relative positioning therein. As used herein, the term &#34;density of the weight block&#34; refers to the composite, overall density of the block as a whole. The density may be constant or variable through the different regions of the block. The weight block is symmetric in shape about its centerline 24, prior to establishment of the line of demarcation for truncation. 
     As shown, the head portion 10 is defined as a spherical segment whose top surface 18 is generally concentric with the outer surface of the ball. As a regulation bowling ball is of 8.59 inch diameter, the radius of curvature 42 for top surface 18 is in the order of 3.07 to 3.80 inches, corresponding to a spacing distance between the ball surface and head of between about 1.225 and 0.495 inches. In General, this distance &#34;d&#34; is typically not less than one-half inch to provide sufficient thickness of the shell to protect the core and to maintain proper rolling characteristics. With certain formulations for the shell, it is expected that this distance can be lessened. The radius R of the base of the head portion is generally defined by the distance between two perpendicular radii 42, the 90° angle 40 therebetween being bisected by the centerline of the core block, subject to about plus or minus 1/2 inch deviation. The core is positioned within the ball such that its vertical centerline axis 24 either aligns with the vertical centerline of the ball as defined by the positioning of an alignment pin as known in the art, or offset to a maximum of about 30 degrees. The ball centerline typically passes through the location of the ball label at its upper end, which defines the &#34;top&#34; of the ball, and further represents the area in which the finger holes are drilled. 
     Extending downwardly towards the geometric center of the ball 26 is body portion 12, preferably in the form of a cylinder having its axis along the core vertical axis 24. As depicted in FIG. 1, the cylinder has the radius R of the spherical head segment 10, but may be of a lesser radius as will be illustrated and explained hereinafter. The length of the body is chosen to be no greater than the diameter of the head (2R), extending to a point (such as 20) below the horizonal centerline axis 22 of the ball. With a radius of curvature 42 between 3.07 and 3.80 inches, the radius R of the head is between 2.17 and 2.685 inches, subject to the 1/2 inch deviation. The horizontal centerline of the ball typically is aligned with the ball centerline, but may be displaced slightly depending on the positioning of the block within the shell. 
     As shown FIG. 1, the body may be without surface protrusions. The invention, however, encompasses body configurations including annular rings of varying dimensions as shall be illustrated herein. 
     In addition to a cylindrical body, the present invention contemplates that the weight block body may be in the form of a regular parallelepiped, subject to the same dimensional restraints as the cylindrical body type. As shown in FIG. 3, the radius R of the head runs to the maximum distance or radius of the surface of the body from the block vertical centerline 24, shown in the Figure as a regular hexagon with sides 30, with radius R defining the distance to the vertices 32 of the sides. A preferred arrangement for such parallelepiped body form is with 6 or more sides. 
     Referring again to FIG. 1, the block terminates at its lower end in tip portion 14 which is shown as being of a tapered configuration. The tip portion is chosen such that the volume and accordingly the weight of the portion of the weight block below the horizontal centerline 22 of the ball is less than the weight of the portion above the centerline. For weight blocks of constant density, the weights of the portions are directly proportional to their volumes. For the embodiment of FIG. 1 the weight of the upper portion, above centerline 22, corresponds to the sum of the weights of the head and the portion of the body above the centerline 22. The volume of the head (without truncation) is represented by the formula V head  =l/6 h (3R 2  +h 2 ), while the volume of the upper portion of the body is represented by the formula V b1  =R 2  l 1 . Similarly, the volume of the lower portion of the body is represented by V b2  =R 2  l 2 . Using these formulas, an appropriate weight value for the tip can be determined and dimensions assigned, with regard to the total weight of the ball, weight loss due to truncation, and weight offset after drilling requirements. Additional adjustments vcan be made for local variation in block density. 
     In order to provide additional eccentricity of mass, the weight block is truncated by a plane; the block mass lying on one side of the plane removed. The plane is located at an angle of between zero to less than 90 degrees from the vertical centerline of the weight block, and is positioned to remove no more than half the mass of the block. 
     As depicted in FIG. 1, the vertical plane 100, parallel to the vertical centerline 24 of the block and thus at an angle of 0 degrees thereto, defines a plane beyond which the block is truncated or removed, resulting in the core structure for the ball. When vertical, the plane is generally preferably located no more than about 1.5 inches inwardly from the maximum radius of the block, which in FIG. 1 is defined by the vertical sidewall 102 of the body. The resulting eccentricity of mass about the vertical axis of the resulting core permits modified roll characteristics to develop as the ball travels down the lane. As best seen in FIG. 3, the lines of intersection 106 between the truncating plane and the surfaces of weight block may be rounded as shown at 108 without departing from the spirit or scope of the invention. 
     As shown in FIG. 2, the body 12 may further include a cylindrical ring portion 28 encircling the body. As used herein, the term &#34;ring&#34; refers to an encircling protrusion upon the surface of the body portion, whether defined by planar or curved surface elements, so long as the ring is symmetrical about its circumference. Thus, the ring may be trapezoidal in cross-section as shown in FIG. 2, rectangular as depicted in FIG. 4a, generally spherical as depicted in FIG. 4b, or a combination of such or other alternative configurations. Both the height h r  and thickness t r  of the ring are variable. The ring may extend along either the full length or a portion of the body. The thickness t r  of the ring, however, is not to exceed approximately 11/2 inch at its thickest point. The size and positioning of the ring must be considered in performing the upper and lower block portion weight calculations. In preferred embodiments, the height centerline of the ring is located on or above the horizontal centerline of the weight block. 
     As shown in FIG. 2A, a plane of truncation 104 may alternatively be established at an acute angle to the block centerline 24. The plane is established and located such that the truncated portion 110 (as shown in phantom), is removed from the lower portion of the block. The plane extends outwardly from the centerline towards the head of the block. Angle &#34;a&#34; between the plane and the block centerline is chosen to be less than 90 degrees, the plane being positioned so that less than half the mass of the block is removed. In a first preferred embodiment the plane is positioned such that the entire tip portion is not removed. In a second preferred embodiment, the plane does not intersect the block centerline 24 within the block. Both conditions are illustrated in FIG. 2A. 
     The plane angle &#34;a&#34; may be in either a positive or negative sense with respect to the block centerline. Accordingly, FIG. 2B depicts an embodiment where the plane 104 transects the upper portion of the block, the truncated portion 112 being removed from the head portion 10 and the upper portion of body 12. Angle &#34;a&#34; is shown as being at 30 degrees to the vertical. The configuration of the block and the degree of truncation are chosen such that the weight of the portion of the weight block below the centerline 22 is still less than the weight of the truncated upper portion. 
     The tip portion may be of varied configuration so long as its maximum radius does not exceed the radius of the body. The distal end of the tip may include a pointed, flat, or curved termination. The profile of the tip may be either smooth or stepped, and may be cylindrical or include a reverse taper or widening towards its distal end, so long as it maintains radial symmetry about the vertical center line 24 of the block. Within such guidelines, the tip may bear planar faces as well as a smooth curve about its circumference. It is preferred, however, that the tip surface be curved, and terminate in a spherical cap 34 whose surface is concentric with the ball surface, with a spacing d&#39; from the ball surface of no more than approximately 1.5 inches nor less than 0.5 inches. 
     As shown in FIG. 5, the body portion 12 of the weight block may be of a radius less than the radius R of the head. In such a case, there must be transition region 36 between the radius R of the head and the radius of the body. The transition region can be defined by an angular surface 38. If the head is defined as a spherical segment between the rotated included right angle 40 bisected by centerline 24 , the surface 38 may preferably lie along the rays 42 of the right angle. Plane geometry teaches that the rays 42, when extended downwardly beyond the vertex of the right angle 40, define the diagonals of a square of sides 2R. Thus, the extension of the rays define the maximum extent for the length of body portion 12. As shown in FIG. 5, this total maximum length includes any transition area 38. The tip portion 14 has an upper portion of a radius equal to that of the body, terminating in generally spherical cap 34. Depending on the relative size of the head and body portions, the vertical truncation plane 100 may extend through, and truncate, only the head portion, as shown. 
     FIG. 6 depicts another alternative embodiment which utilizes a tip portion 14 of varying diameter. As shown therein, the body 12 includes a trapezoidal ring 58, the lower end of which terminates the body portion at 56. The tip 14 includes a central cylindrical portion 44 capped by a second cylindrical portion 46 of greater diameter bearing spherical top 48. To facilitate manufacture and avoid sharp corners which might induce stress cracking, transition elements 50 and 52 are utilized between cylindrical portion 44 and the body 12 and second cylindrical portion 46, respectively. The maximum radius of the tip, at the line 56 of intersection with the body, does not exceed the radius of the body 12. In this embodiment, the offset truncation plane 104 at an angle a of 40 degrees traverses the tip and body ring 58. 
     FIG. 7 depicts an embodiment where body 12 bears a trapezoidal ring 60, and where tip 14 is of a stepped, generally tapered form. First portion 62 tapers from the radius of the body to a smaller radius at 64, which defines the outer edge of horizontal shoulder 66. The tip ends in cylindrical portion 68, having a slightly curved cap 70. Again, the geometry of the tip falls within the guidelines set forth above. The vertical truncation plane 100 cuts both the head and body portions. 
     FIG, 8 illustrates yet another embodiment of the invention. In that embodiment body portion 12 bears ring 72 along the entirety of its length. Tip 14 is of cylindrical configuration of a radius less than that of the body, whereby step 74 is developed at the body-tip intersection. The tip terminates in spherical cap 76. Here the angular truncation plane 104 at an angle of 45 degrees intersects only the tip. 
     It is to be appreciated that modification to the invention as described and depicted herein, can be applied without departing from the spirit thereof. Accordingly, the scope of the present invention is to be measured by the appended claims.