| 摘要 |
PURPOSE:To drastically enhance the roundness of a bearing pressure insertion part in spite of a motor casing made of a resin by carrying out the insertion of a bearing under pressure before the temp. of the resin material injected in a mold lowers to the glass transition temp. thereof after the detachment of the resin material from the mold. CONSTITUTION:A resin material is detached from an inside mold B by pulling during a period when the temp. of the mold is higher than the glass transition temp. of the resin material and the resin material is yet in an activated state and advanced in crystallization and a bearing 5 is inserted in a bearing pressure insertion part 6 before the temp. of the inner peripheral surface of said insertion part 6 become lower than the glass transition temp. and, thereafter, the resin material is cooled to room temp. to mold a casing 1. In the temp. lowering process after the pressure insertion of the bearing, the resin material is molded and shrunk while it gradually follows the shape of the bearing so as to conform to the surface of the bearing inserted under pressure and, as a result, the inner peripheral surface of the bearing pressure insertion part 6 becomes a state near to roundness almost coming into contact with the outer peripheral surface of the bearing 5 and no locally offset pressure insertion stress is applied to the bearing 5 and the deformation of the bearing 5 can be effectively avoided. |
