Bat for baseball or softball and manufacturing method thereof

The present invention relates to a bat for baseball or softball which enables a ball to fly farther and a manufacturing method thereof.

For baseball or softball players, a bat with which enables a ball to fly farther is attractive. For example, in practicing catching, a coach or player hits fungoes repeatedly and when he intends to hit a ball to the outfield, the ball must fly far enough to reach the outfield. For this reason, a team is expected to have, as a fungo bat for rubber-ball baseball, at least one bat with which a ball easily flies far enough.

In the present invention, bats not only include metal bats such as aluminum alloy bats but also bats of easily workable woods and bats of synthetic resin such as carbon FRP. A bat is comprised of a tip part, a ball-hitting part, a tapered part and a grip part. The present invention concerns improvement of the ball-hitting part.

In order to increase the flying distance, it is necessary to decrease deceleration of the bat at the time of collision and increase rebound of the bat. It has long been known that reduction of ball deformation at the moment of hitting is effective as an approach to increasing the rebound. As a means to reduce deformation of the ball at the moment of hitting, a conventional technique that a bat surface is covered by an elastic material has been disclosed (for example, see JP-A No. 2003-019236).

At the moment of hitting, the ball contacts the bat in a surface-to-surface manner and deforms. Therefore, one approach to reducing deformation of the ball is to decrease the area of contact between the ball and the bat. In this sense, to make the surface of the ball-hitting part of the bat uneven is one possible option. As an effort in this direction, in conventional techniques for wooden bats as described in JP-B No. 33 (1958)-001279 and JP-A No. 2002-282405, bumps and dents (concave and convex parts) are made on a bat outer surface by compression forming.

The techniques described in these patent documents are characterized in that bumps and dents are irregularly made on a bat surface. On the other hand, JP-Y No. 36 (1961)-027915 describes a technique that bumps and dents are made in a regular pattern longitudinally. However, this patent document does not disclose any bat manufacturing method and the bat described in the document does not conform to the standards for baseball and softball gear.

As a method of minimizing the possibility of hitting a foul ball or grounder, making bumps and dents transversely may also be thought to be effective. There also exists a conventional technique that grooves and ridges are transversely made in a regular pattern (JP-Y No. 30 (1955)-018934).

In the above technique, grooves and ridges are made spirally. Another document describes a technique of making annular grooves (JP-U No. 53 (1978)-085255).

In the technique described in JP-Y No. 30 (1955)-018934, grooves and ridges are made on the tapered part of the bat as well. However, the tapered part of the bat is not supposed to hit the ball and if the purpose is to increase the flying distance, grooves and ridges should be made only on the ball-hitting part. Also according to JP-U No. 53 (1978)-085255, the top of a ridge between grooves is smooth and flat, so the area of contact with the ball at the moment of hitting cannot be small enough. Therefore, this method is not so effective in reducing deformation of the ball going to fly.

Besides, in the bats as described in JP-Y No. 30 (1955)-018934 and JP-U No. 53 (1978)-085255, grooves and ridges are exposed on their surfaces and the bats do not conform to the standards for baseball and softball gear.

The present invention has been made in view of the above circumstances and provides a bat which enables a ball to fly farther than conventional bats and conforms to the standards for baseball and softball gear and also provides a manufacturing method thereof.

In order to achieve the above object, according to one aspect of the present invention, there is provided 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 rubber, resin or leather sheet.

According to another aspect of the invention, a method of manufacturing a baseball or softball bat of wood or carbon FRP comprises the steps of forming a lot of concave grooves and convex ridges alternately in parallel on a surface of a cylindrical ball-hitting part of the bat excluding a tapered part by cutting with a lathe using an ordinary tool or forming tool or grinding stone, and making the convex parts round and curved outward.

According to a further aspect of the invention, a method of manufacturing a metal baseball or softball bat comprises the steps of forming a lot of concave grooves and convex ridges alternately in parallel on a cylindrical ball-hitting part of the bat in an axial direction by a lathe using a spatula or roller, and making the convex parts round and curved outward.

According to another further aspect of the invention, a method of manufacturing a baseball or softball bat made of synthetic resin such as carbon FRP which uses a die comprises the steps of forming a lot of concave grooves and convex ridges alternately in parallel on a cylindrical ball-hitting part surface of the bat, and making the convex parts round and curved outward.

According to the present invention, the ball-hitting part of the baseball or softball bat has concave and convex curved surfaces and at the moment of hitting a ball, the area where the ball contacts or rebounds is almost linear and the area of contact is smaller, so that ball deformation is reduced and the flying distance is increased.

When the area of contact between the bat and the ball is smaller, friction between the ball and the bat at the moment of hitting is reduced and if the bat hits the ball off its center, slippage is likely to occur, leading to a foul. However, in the present invention, since the surface of the ball-hitting part of the bat is covered by a cylindrical rubber, resin or leather sheet, the problem of reduction in friction between the ball and the bat is resolved and the ball is more likely to fly forward.

In the baseball or softball bat according to the present invention, the cylindrical ball-hitting part has an axial cross section shape that a lot of concave-surfaced grooves and convex-surfaced ridges are arranged in parallel alternately along a circumference of the bat, so the bat is two to three times as stout and durable as conventional bats.

In the baseball or softball bat according to the present invention, the concave and convex parts lie under the rubber, resin or leather sheet wound around the ball-hitting part, so the bat does not give a sense of discomfort and conforms to the standards for baseball and softball gear and enables a ball to fly forward easily.

The baseball or softball bat according to the present invention can be manufactured by an easy process and supplied at low cost if the material is wood or synthetic resin.