| 摘要 |
PURPOSE:To obtain a lightweight dust cap and keep internal loss appropriate by forming a copolymer foaming film consisting of stylene and maleic anhydride in a dome shape. CONSTITUTION:A copolymer foaming film consisting of stylene and maleic anhydride is heated at 110-125 deg.C by a heater or other heating means, pressed on a domelike mold at a room temperature to form the entitled cap like a dome. Thus, the domelike dust caps with 0.054g/cm<2> and 0.027g/cm<2> density can be obtained from 20 times and 40 times foaming film sheet, respectively. Moreover, the internal loss tandelta of 0.03-0.04 can be obtained by an oscillation leading method. Since the density is extremely smaller in comparison with an ordinary dust cap, the weight of an oscillation system can be sharply reduced. In addition, the foam of the foaming material is independent air bubbles, so that the equipment is prevented from gas permeability completely. Since the internal loss is also large, self oscillation can be suppressed. |
