| 摘要 |
PURPOSE:To improve surface roughness and dimensional accuracy by attracting a thermoplastic sheet by evacuation to the inside surface of a metallic mold then packing preliminarily expanded particles into the cavity and melt-sticking the same to the sheet by hot wind. CONSTITUTION:A thermoplastic resin sheet 12 is loaded on the cavity surface of a stationary mold 1 and a movable mold 3 and the molds are clamped. The inside of spaces 2, 4 is evacuated through an evacuating pipe 10 to attract the sheet 12 to the cavity surface. Preliminarily expanded particles 13 are charged and packed together with air through an air feed port 14. The evacuation through the pipe 10 is then stopped and steam of 110 deg.C or the like is introduced through a steam introducing pipe 9 and the port 14 into the product cavity. The particles 13 are melt-stuck and united to the sheet 12 by the above-mentioned method by which the expendable pattern having substantial strength and excellent surface roughness and dimensional accuracy is obtd. |
