| 摘要 |
PURPOSE:To eliminate the need for machining and simplify manufacture, by covering the outer periphery of a roller shaft with a thermoplastic elastomer having a specified hardness by injection molding. CONSTITUTION:An aluminum pipe with an axis size is set in a cavity of a metallic mold for injection molding finished to a predetermined dimensional accuracy and having a polished surface. A molding resin is a polyester resin called 'Hytrel,' and is injection molded under the conditions of a resin temperature of 250 deg.C and an injection pressure of 1,500kg/cm<2> to cover the roller shaft 23 with an elastomer resin. The thermoplastic elastomer 22 has a Shore hardness (D-scale) of 40-70. Accordingly, an elastomer 22 most suitable for a platen roller in a dot impact type printer is molded. |
