| 摘要 |
PURPOSE: To reduce the cycle times by being subjected to a dwell time while keeping molded articles obtained after a deep-drawing process or the pressing process at a temperature and a pressure and being immediately removed from the mold. CONSTITUTION: A polyurethane part is introduced into a deep-drawing mold or a fragmented polyurethane material is introduced into a pressing mold and is then pressed at a temperature of up to 230 deg.C and a pressure of up to 1,000 bar and preferably up to 300 bar. In a manufacture of a molded article, the molded article obtained after a deep-drawing process or a pressing process is subjected to a dwell time of at least 10 seconds at a pressure of up to 1,000 bar, and preferably up to 300 bar, and then immediately removing it from the mold. In the process, therefore, in which the article is removed from the mold while hot, the procedure of cooling of the molded article in the deep-drawing mold or the pressing mold under pressure is dispensed. Only thereafter the article is cooled outside the deep-drawing mold or the pressing mold. This method results in molded articles which are free from after-shrinkage within considerably reduced cycle times. |
