| 摘要 |
PROBLEM TO BE SOLVED: To provide a soft tennis ball of a new structure wherein the location of a rubber plug being equivalent to a navel can be easily found while eliminating a work to place a marking to indicate the location of the navel for air injection. SOLUTION: This soft tennis ball is equipped with a ball spherical shell 2 which forms the ball body, and a rubber plug 3 for the pierce-penetration of an air injection needle, which protrudes to the inside from the internal surface of the spherical shell 2. The rubber plug 3 comprises a tip end section 3011, a solid column-shape section 302 and a flange section 3013. In this case, the tip end section 3011 is embedded into a wedge shape from the internal surface of the spherical shell 2 to the external surface. The solid column-shape section 302 allows the pierce-penetration of an injection needle, shrinks by the rubber elasticity after the needle is pulled out, and seals the pierced hole to prevent air from leaking. The flange section 3013 is located between the tip end section 3011 and the column-shape section 302, and bonds and fixes the rubber plug 3 to the internal surface of the spherical shell. Then, at the tip end section 3011, a closed-end cylindrical hole 3014, which introduces the injection needle to the column-shape section 302, is provided.
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