Abstract:
Balls are provided for use in baseball or softball, including, for example, a solid sphere, an outer shell of a foamed material, covering the solid sphere, and a material covering the outer surface of the shell. Methods for making a ball and a ball core are also described.

Description:
[0001]    This application calims benefit from U.S. Provisional Applciation No. 60/440,518, filed Jan. 16, 2003. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to balls for use in baseball and softball.  
         BACKGROUND  
         [0003]    The invention relates to balls, e.g., substitute baseballs, softballs and the like, and to methods for making balls.  
           [0004]    Regulation baseballs and softballs typically include a cork and rubber core surrounded with yarn windings and a leather cover. Regulation baseballs and softballs are quite hard and can cause serious injury, especially to younger and/or inexperienced ballplayers. It is therefore desirable to significantly reduce the chance of injury by providing balls that are softer. Various substitute baseballs and softballs have been proposed to address the need for balls that are softer and thus safer than regulation balls. It is important, however, to maintain the performance, durability, and the “look and feel” of substitute balls so that they can function as suitable training balls, and so that the players&#39; enjoyment of the game is not diminished by the feeling that the ball is not a regulation ball.  
           [0005]    One type of ball that has been used for baseball and softball training and recreation includes a mixed rubber and cork core in a hollow sphere form with a layer covering the sphere. The softness and bounce of the ball can be adjusted by increasing or decreasing the number and the size of the pieces of cork in the mixture, and/or by adjusting the wall thickness of the hollow sphere. When struck by a bat, these balls generally sound to the players similar to that of the regulation balls discussed above. However, after certain types of impacts, such as the ball being hit by the bat, the mixed rubber and cork core can be shattered or cracked apart easily. In order to increase durability, the hollow core may be replaced by a solid core. However, this will produce a relative increase in hardness which may compromise safety.  
           [0006]    Others types of baseballs include a core formed of a softer material, such as urethane foam, polyurethane (PU) foam, or rubber foam. For example, U.S. Pat. No. 4,772,019 discloses a game ball formed with a soft, resilient, substantially closed-cell plastic foam core. These balls can be adjusted to be softer than those having a mixed rubber/cork core, and will typically last longer by comparison, but do not provide the player with the feel of a regulation ball while playing.  
         SUMMARY  
         [0007]    In one aspect, the invention features a ball for use in baseball or softball including an inner sphere, an outer shell of a foamed material, covering the solid sphere, and a material covering the outer surface of the shell.  
           [0008]    Embodiments may include one or more of the followings features. The inner sphere is solid. The sphere includes a mixture of a polymer and pieces of cork. The polymer is selected from the group consisting of polyurethane, rubber, and mixtures thereof. The outer shell comprises a polymer selected from the group consisting of polyurethane, EVA, and mixtures thereof. The material covering the outer surface of the shell comprises two panels of material that are stitched together. The material covering the outer surface of the shell is selected from the group consisting of genuine leather, rubber, fabric, PVC, PU, and TPU. The two panels comprise sheets of fabric material with an EVA foam backing. The two panels are bonded by an extra knitted fabric along the edges and stitched together to provide a high seam effect. The material covering the outer surface of the shell includes a layer of rubber molded and vulcanized over the surface. The ball has the dimensions and appearance of a regulation ball.  
           [0009]    In another aspect, the invention features a method of making a ball for use in softball or baseball, including: (a) blending a core polymer with pieces of cork to form a blended mixture; (b) molding and heating the blended mixture to form a sphere; (c) injecting a foamable polymer into a mold under conditions so that the polymer will form a foam shell; and (d) applying the foam shell to the sphere.  
           [0010]    Embodiments of this aspect of the invention may include one or more of the following features. The sphere is solid. The method further includes (e) molding and heating the sphere and the shell to form a core suitable for use in a ball. The applying step includes applying an adhesive to a surface of the solid sphere. The core polymer includes rubber. The molding step further comprises vulcanizing the rubber. The core polymer may include polyurethane. The injecting step includes forming two hemispherical shell portions. The method further includes wrapping the core with a cover. The wrapping step comprises wrapping the ball material with two panels of fabric material with EVA foam backing. The method further includes bonding the panels by an extra knitted fabric along the edges and stitching together to provide a high seam effect. The wrapping step includes wrapping the ball material with a rubber layer. The method further includes vulcanizing the rubber layer.  
           [0011]    Among the advantages of the invention are the following. The balls have good durability and safety. The characteristics of the foamed shell can be controlled over a broad range that allows the amount of rebound or bounce of the ball to be accurately controlled by changing the foam density. The inclusion of the foam shell tends to reduce the chance of injury to a player struck by the ball, compared, for example, with a ball having the whole core made from solid rubber. Moreover, the foamed material is softer than the inner sphere of the core and thus can absorb the external impacts, e.g. baseball batting. The balls can generally be played for a longer time than a similar ball without the foamed shell. In embodiments in which the solid inner sphere is made of a mixture of rubber or polyurethane and cork, the ball will generally produce a crack sound similar to that produced by a regulation baseball or softball. In some implementations, the ball has a feel that is similar to that of a regulation baseball or softball, which will tend to increase the players&#39; enjoyment of the game.  
           [0012]    To further enhance the safety of the invention for the young players, especially for children, in some implementations the ball is covered by a layer of fabric with EVA foam backing. A fabric cover with an EVA foam backing provides further softness of the ball for the players. Extra cloth may be bound along the edges of the fabric panels, to create a high seam effect after the edges of the fabric panels are stitched together. This high seam effect provides good gripping and control for a beginner or trainee.  
           [0013]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will be apparent from the description and drawings, and from the claims. 
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0014]    [0014]FIG. 1 is a view of a ball.  
         [0015]    [0015]FIG. 2 is a view of a core of a ball.  
         [0016]    FIGS.  3 A- 3 B are a cross-sectional view of a mold to an inner sphere of the core.  
         [0017]    [0017]FIG. 4 is a cross-sectional view of a method of making a core shell.  
         [0018]    [0018]FIG. 5 is a cross-sectional view of forming the sphere.  
         [0019]    [0019]FIG. 6 is a view of a second example of a ball.  
         [0020]    [0020]FIG. 7 is a view of a third example of a ball. 
     
    
       [0021]    Like reference symbols in the various drawings indicate like elements.  
       DETAILED DESCRIPTION  
       [0022]    Referring to FIGS. 1 and 2, a ball  14 , used in baseball or softball, includes a core  10 . Core  10  is covered with two panels  15 ,  16  that are stitched together with a durable thread  17  (e.g., nylon, polyester or vinyl thread). Core  10  includes a solid, inner sphere  13  placed within two hemispherical outer core shells  11 ,  12 , each having a wall thickness T.  
         [0023]    The construction of core  10  and the material used to form core  10  enables a ball to be durable and safe while also providing the “look and feel” of a regulation ball.  
         [0024]    The inner sphere is formed of a mixture of a polymer, such as polyurethane or rubber, and pieces of cork. The cork pieces may be of any desired size. The polymer mixture generally includes other, non-resilient, processing components that are selected to bind the pieces of cork together upon heating of the polymer mixture. The inner sphere preferably has a diameter of about 3.0-8.0 cm, and weighs about 50-80 grams.  
         [0025]    The outer shell is formed of a foamed polymeric material, preferably polyurethane or ethylene vinyl acetate (EVA). The outer shell preferably has a wall thickness T of 1.0-2.0 cm, and weighs about 50-90 grams. Examples of suitable properties for a 9″ baseball and a 12″ softball are given below. The density of the outer shell and/or the inner sphere may vary for balls of other sizes.  
         [0026]    9″ Baseball:  
         [0027]    Whole core diameter—7.07-7.18 cm  
         [0028]    Whole core weight—104-114 gm  
         [0029]    Thickness of the outer shell—1.0 cm  
         [0030]    Density of the shell—0.4-0.54 gm/cm 3    
         [0031]    Density of the inner sphere—0.7-0.84 gm/cm 3    
         [0032]    C.O.R.—0.42*  
         [0033]    12″ Softball:  
         [0034]    Whole core diameter—9.4-9.5 cm  
         [0035]    Whole core weight—136-144 gm  
         [0036]    Thickness of the outer shell—1.2 cm  
         [0037]    Density of the shell—0.2-0.37 gm/cm 3    
         [0038]    Density of the inner sphere—0.28-0.45 gm/cm 3    
         [0039]    C.O.R.—0.53*  
         [0040]    * C.O.R. (Coefficient of Rebounce) is equal to the measured rebounce of a ball after a free drop to the ground from 2 meter height.  
         [0041]    The density and bounce characteristics can be changed to suit particular applications. For example, the density of the outer shell can be varied by adjusting the amount of sponging agent included in the foamed polymeric material, while the density of the inner sphere can be varied by adjusting the size and/or number of the cork pieces.  
         [0042]    The shell is generally adhered to the outer surface of the inner sphere by an adhesive or glue, as will be described below. However, if desired, other techniques of joining the sphere and shell may be employed.  
         [0043]    The core (inner sphere and shell) preferably weighs about 100-170 grams in total, depending on the requirements of the players.  
         [0044]    The cover is made of a sheet material such as genuine leather, fabric, poly vinyl chloride (PVC), poly urethane (PU), or thermoplastic polyurethane (TPU). The cover may consist of separate panels of material stitched together or may be formed from molded rubber.  
         [0045]    Referring to FIGS.  3 A- 3 B, inner sphere  13  is formed by forming a mixture  26  such as mixing rubber and cork (for a baseball), or a urea/melamine adhesive and latex blend and cork (for a softball), together with other process components (see examples below) that bind the cork and polymer together by open rolling and kneading. For example, in constructing a baseball, mixture  26  has the following ingredients:  
                                                                         Component   Weight (g)   Weight %                                        Natural Rubber   4.25   7.359           Reclaimed (Natural) Rubber   12.74   22.061           Light Calcium   3.77   6.528           Yellow Oil   0.42   0.727           Sulfur   0.51   0.883           Zinc Oxide   0.68   1.177           Stearic Acid   0.51   0.883           Dibenzothiozyl Disulfide   0.31   0.537           Accelerator for Rubbers   0.25   0.433           Rubber anti-aging agent   0.34   0.589           Cork   33.97   58.823                      
 
         [0046]    In another example, in constructing a softball, mixture  26  has the following ingredients:  
                                                                         Component   Weight (g)   Weight %                                        Cork   67.33   76.338           Urea-melamine Adhesive   13.47   15.272           Latex   6.73   7.630           Anti-bacteria agent   0.67   0.760                      
 
         [0047]    Mixture  26  is placed into a concave hemispherical mold  27  and covered by another concave hemispherical mold  28 . The two concave hemispherical molds  27 ,  28  are locked together by clamps  29  and  30  to mold the mixture  26  inside in a solid spherical shape. Mixture  26  is heated in molds  27 ,  28 , e.g., at 140° C. for 15-20 minutes. The molded mixture  26  is cooled and removed from molds  27 ,  28  to form inner sphere  13 . In this embodiment, inner sphere  13  has a diameter of 3.0-5.3 cm for a baseball and 5.7-8.0 cm for a softball.  
         [0048]    Referring to FIG. 4, two hemispherical core shells,  11 ,  12  are formed by mixing together polyurethane along with other components, such as those shown below to form a polyurethane mixture  31 . For example, in constructing a baseball or softball, the following ingredients may be used to form mixture  31 .  
                                                   Component   Ratio (g)                           Polyether Polyol   100           Methylene Bisphenyl Isocyanate (MDI)   20-55           Water   0.5-2.5           Diazobicyclo(2.2.2)octance (DABCO)   0.1-0.3           Dibutyltin Dilaurate (T-9)   0.08-0.23           Silicone oil   0.2-0.8                      
 
         [0049]    In the aforesaid formula, water is used as a sponging agent, DABCO &amp; T-9 as an accelerator, and silicone oil as a stabilizer.  
         [0050]    Mixture  31 , in liquid form, is injected into a set of molds  32  (FIG. 4). Heating mixture  31  at 50° C. for 15-20 minutes inside mold  32  causes a chemical reaction, causing mixture  31  to foam. The mixture is allowed to fill the mold, after which the finished hemispherical shell is removed from the molds to form outer shell  12 . The process is repeated to form outer shell  11 . In this embodiment, the hemispherical shell has a wall thickness of 1.0-2.0 cm.  
         [0051]    Referring to FIGS. 5A and 5B, circumferential edges  33  &amp;  34  of the resulting hemispherical shells are sanded to provide a rough surface. A thin glue or adhesive  35 , which is a kind of glue as well as a curing agent under the heating process described hereunder, is applied over the surface of the inner sphere  13  and the inner surfaces of the hemispherical outer shell  11  and  12  respectively and then heated at a temperature of 70° C. for 10 minutes to accelerate the curing process. The inner sphere  13  is placed on the inner surface of hemispherical outer shell  12  and covered by hemispherical outer shell  11  (FIG. 5) for another 10 minutes while the curing process is still going on. The inner sphere  13  and the outer shells  11  and  12  are then adhered under the curing process and core  10  is formed. The outer surface of the resulting core  10  is buffed and sanded. Core  10  is covered by panels  15 ,  16  which are stitched together.  
         [0052]    In other embodiments, core  10  can be placed in other constructed balls. For example, in FIG. 6, a ball  18  is formed by covering core  10  with two panels of material  19 ,  20 , e.g. knitted fabric and an EVA backing, that are bonded together by an extra knitted fabric  21  and stitched together with durable thread  22  (e.g., nylon, polyester or vinyl thread). The material is formed by laminating a layer of EVA foam underneath a fabric sheet. The material is cut into two panels in the shape of regular baseball or softball cover. The edge of each fabric panel is then bound by the extra cloth  21 , and the edges of the fabric panels are stitched together so as to form a ball cover having a high seam effect, i.e., the seam is raised above the surface of the ball, due to the extra cloth layer at the seam.  
         [0053]    In another embodiment, a ball  23  is formed by covering core  10  with a layer of rubber  24  that is molded with a raised stitching pattern  25  to simulate the stitching of a regulation baseball or softball.  
         [0054]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.