| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve a restitution characteristic by setting the natural frequency in the cylindrical direction of the hitting area of a bat for baseball played with hard rubber balls at specified Hz. SOLUTION: The natural frequency in the cylindrical direction of the hitting area 3 of a bat 1 for baseball played with hard rubber balls is set at 1450Hz or lower. The average thickness of the site 3a of the hitting area 3 that is 50 to 200mm from the head 2 of the bat is made higher than the average thickness of other sites 3b, 3c, and the natural frequency in the cylindrical direction is set at 1400Hz or lower. The site 3a whose average thickness is higher may be formed in the inside of the hitting area 3 of the bat 1 or in the outside thereof. By forming the bat 1 of an aluminum alloy whose natural frequency in the cylindrical direction thereof is low, the natural frequency can be made low and the restitution characteristic can be improved. The formation of the thicker section 3a helps increase the effective mass of the bat without causing a loss in strength and improve the restitution characteristic.</p> |
