| 摘要 |
PURPOSE:To obtain a vibration sheet becoming the thinner as the diameter becoming the larger by blow-molding thermoplastic resin in the mold cavity having shape composed of two opposite truncated cones connected at a maximum diameter and having a continual part at the maximum diameter and cutting the molded object at the part of maximum diameter. CONSTITUTION:Molten thermoplastic resin is extruded from the extrusion orifice 31b by an extruder etc. and suspended as a tube 32. Then, the lower end of the tube 32 is closed by clamping molds 21, 21 and compressed air is blown out from the blow nozzle 31a and the tube 32 is pressed to the inner wall of the cavity 22 of molds 21, 21. The hardened molded article is taken out from the mold 21 and two cone type vibration sheets are obtained by cutting it at the maximum diameter part. Because the vibration sheet is formed by being pressed, elongated and inflated along the radial direction of the tube 32, the sheet is formed so as to be the thinner as its diameter being the larger. |
