MOLD-RETAINING APPARATUS

PURPOSE:To facilitate assembling and disassembling of mold parts at an ordinary temperature and keep centering by itself with high precision at high temperature, by making central and peripheral part of the mold with a material having small coefficient of linear expansion, intermediate part with large coefficient material and engaging parts with each other. CONSTITUTION:A collet part 12 composed of a material (e.g. stainless steel) having large coefficient of linear expansion is arranged so as to sandwich the part between a tubular central mold part 11 composed of a material (e.g. ceramics) having small coefficient of linear expansion and a ring part 14 having small coefficient of linear expansion and fixed by fitting. Above-mentioned apparatus facilitates assembling and disassembling of the mold part 11 to the mold-retaining components 12, 14, since there is a space between the mold 11 and the collet part 12 at an ordinary temperature. When the apparatus is heated by a heater 16, the space between the mold 11 and the collet part 12 becomes 0. Therefore, the mold 11 and the mold-retaining components 12, 14 are automatically centered in high precision and the positional precision of the mold 11 on molding can be enhanced.