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/cm³

[0031] Density of the inner sphere—0.7-0.84 gm/cm³

[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/cm³

[0038] Density of the inner sphere—0.28-0.45 gm/cm³

[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. 3A-3B, 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: 1

[0046] In another example, in constructing a softball, mixture 26 has the following ingredients: 2

[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. 3

[0049] In the aforesaid formula, water is used as a sponging agent, DABCO & 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 &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.