| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that it is difficult to form many minute holes in a base material because of problems of machining and rigidity. SOLUTION: The base material is formed by laminating a skin layer made of a Noryl(R) material, having superior hole machinability and heat resistance, on the top and reverse surfaces of a foamed core, and when the base material is heated after having many minute holes bored, secondary foaming of a foamed core layer occurs to form a hole whose internal surface is large nearby the top and reverse surfaces of the base material thickness and small nearby the center of the base material thickness. Consequently, the internal diameter is made narrow on the inner side of the base material to decrease an aperture rate, so the rigidity of the base material can be deterred from decreasing. Further, the internal diameter of the initial aperture can be made narrow through the secondary foaming, so the difficulty of machining for forming minute initial holes with high density is reduced. COPYRIGHT: (C)2005,JPO&NCIPI |
