Bat for baseball or softball

Abstract

A bat for baseball or softball includes a core member having a depression at a portion to be a ball-hitting portion, and an elastic body attached to the depression and forming the ball-hitting portion. The elastic body is formed of urethane elastomeric foam having specific gravity of at least 0.45 and at most 0.60, JIS C hardness of at least 54 and at most 82, and modulus of elasticity in 300% elongation of at least 3.85 MPa and at most 5.6 MPa.

1 . A bat for baseball or softball, comprising:
 a core member having a depression at a portion to be a ball-hitting portion; and   an elastic body attached to said depression and forming said ball-hitting portion; wherein   said elastic body is formed of urethane elastomeric foam having specific gravity of at least 0.45 and at most 0.60, JIS C hardness of at least 54 and at most 82, and modulus of elasticity in 300% elongation of at least 3.85 MPa and at most 5.6 MPa.   
   
   
       2 . The bat for baseball or softball according to  claim 1 , wherein
 said elastic body has a surface layer and an inner portion; and   hardness of said surface layer is higher than that of said inner portion, and difference in hardness between said surface layer and said inner portion is set to be at least 7 and at most 15 in JIS C hardness.   
   
   
       3 . The bat for baseball or softball according to  claim 1 , comprising
 a lubricant layer provided between said elastic body and said core member.   
   
   
       4 . The bat for baseball or softball according to  claim 1 , wherein
 said elastic body has   a first characteristic that a hysteresis value is at least 0.15 J and at most 0.42 J, which hysteresis value is obtained by subtracting, from an integrated value of products between load and displacement when compressive load of 800N is applied at a rate of 10 mm/min. to a part of said elastic body detached from said core member, an integrated value of products between the load and displacement when the compressive load is removed at the same rate; and   a second characteristic that rebound height of a weight in accordance with ASTM-D2632 is at least 121.2 mm and at most 133.6 mm.   
   
   
       5 . The bat for baseball or softball according to  claim 1 , wherein
 said elastic body is formed of fine cell urethane elastomeric foam having the cell size of at least 75 μm and at most 115 μm.   
   
   
       6 . The bat for baseball or softball according to  claim 1 , comprising
 a tip portion and a grip portion; wherein   a bottom portion of said depression has a tip-end-side tapered portion positioned on the side of said tip end, a grip-end-side tapered portion positioned on the side of said grip portion, and a central portion positioned between said tip-end-side tapered portion and said grip-end-side tapered portion; and   outer diameter of said core member forming said central portion is made equal to or smaller than a minimum value of outer diameter of said core member forming said tip-end-side tapered portion and said grip-end-side tapered portion.