Bat for baseball or softball and manufacturing method thereof

Abstract

A baseball or softball bat which enables a ball to fly farther than a conventional bat. The bat is made of metal, wood or carbon fiber-reinforced plastic and its cylindrical ball-hitting part has an axial cross section shape as follows: a lot of concave-surfaced grooves and convex-surfaced ridges are arranged in parallel alternately along the circumference of the bat and the convex parts are round and curved outward. The concave and convex parts are covered by a cylindrical sheet of polyurethane elastomer or similar material. Also, a metal baseball or softball bat is manufactured by grooving the cylindrical ball-hitting part surface by a lathe using a roller.

1 . A baseball or softball bat made of metal, wood or carbon fiber-reinforced plastic, wherein in an axial cross section shape of a cylindrical ball-hitting part of the bat,
 a lot of concave-surfaced grooves and convex-surfaced ridges are arranged in parallel alternately along a circumference of the bat with the convex parts being round and curved outward; and   in order to prevent the concave and convex parts from being exposed on a bat surface, the bat surface is covered by a cylindrical or truncated cone-shaped rubber, resin or leather sheet.   
   
   
       2 . The baseball or softball bat according to  claim 1 , wherein the concave and convex parts are spaced at internals of 5-20 mm and at the moment of hitting the ball, two to five ridges contact the ball and the depth of the grooves is in the range of 0.5-5.0 mm. 
   
   
       3 . The baseball or softball bat according to  claim 1 , wherein the baseball bat is a fungo bat. 
   
   
       4 . The baseball or softball bat according to any of  claims 1  to  3 , wherein outer circumferential surfaces of the concave and convex parts are covered by a cylindrical sheet or net made of 0.5-3.0 mm thick rubber, resin or leather. 
   
   
       5 . A method of manufacturing a wooden baseball or softball bat comprising the steps of:
 fixing a bat by a bat fixing device;   supporting the bat by a cutting support device;   moving a cutting fixing device to the vicinity of the bat;   inching the fixing device until a cutting tool touches a bat surface;   making cuts in the bat by rotation of a bat fixing part;   forming a lot of concave grooves and convex ridges alternately in parallel on a cylindrical ball-hitting part surface of the bat by cutting with a lathe with a control unit using an ordinary tool or forming tool or grinding stone; and   making the convex parts round and curved outward.   
   
   
       6 . A method of manufacturing a metal baseball or softball bat comprising the steps of:
 controlling a pressing force using a pressure gauge of a pressure generator to attain a prescribed level;   forming a lot of concave grooves and convex ridges alternately in parallel on a surface of a cylindrical ball-hitting part of the bat by activating a drive unit to rotate the bat; and   making the convex parts round and curved outward using a spatula or roller.   
   
   
       7 . A method of manufacturing a baseball or softball bat made of synthetic resin such as carbon fiber-reinforced plastic comprising the steps of:
 putting a bat forming material of a desired shape as a prepreg, FRP such as resin-impregnated carbon fiber or glass fiber, around a bat-shaped iron rod as a mandrel;   releasing the mandrel from the prepreg;   forming a lot of concave grooves and convex ridges alternately in parallel on a surface of a cylindrical ball-hitting part of the bat;   putting the prepreg in a die which has curved surfaces matched to a shape of a bat with round surfaces curved outward;   then, sending compressed air into the die to press the bat forming material against the die and form a bat by hot molding; and   then, taking a molded bat out of the die.