| 摘要 |
<p>PURPOSE: To form a hollow space of a hollow body and to fit each required characteristics in relation to balance, vibrational behavior, wt. distribution and stability tendency without changing remarkably a mold by injecting a matrix contg. a reinforcing fiber material and an inert gas under pressure, in particular nitrogen into the mold. CONSTITUTION: A mold for manufacturing walls with various thicknesses is partly heated or cooled and in this instance, to obtain a wall with a relatively large thickness, the region of this mold corresponding to this is kept at lower temp. that of the region for obtaining a wall with a small thickness. In this instance, a matrix system contg. a reinforcing fiber material and an inert gas under pressure, in particular nitrogen are injected into the mold. A proper hollow space is formed thereby in a hollow body of each of a head and a shaft of ball game racket frames.</p> |
