| 摘要 |
PURPOSE:To enable the titled method to make stable and forced pulling-out processing without generating deformation on a product, by using an external mold having such a recessed part as to form a provisional protrusion in the external circumference of a cylindrical member along an opening part in a circumferential direction on an undercut part side of the opening part in the circumferential direction of a circumferential surface part of the cylindrical member. CONSTITUTION:A cylindrical member 1 is formed by filling out the inside of a space constituted of external molds 5a, 5b and core molds 6a, 6b with molten synthetic resin material. An opening side part 2a of an undercut part 3 of the cylindrical member is made into a high-temperature state, the other side part is molded and solidified by cooling the same and a part deforming at the time of forced pulling-out is minimized. The core mold is pulled out forcibly from the opening part of the undercut part 3 under this state and the core mold is pulled out of the cylindrical member by widening the opening part under a high-temperature state. The widened opening part is left cooled, the diameter of the same is contracted and made into an almost a form at the time of molding. As a provisional protrusion 8 is formed along the external circumference of the cylindrical member on the undercut part side of the opening part 4 in a circumferential direction, insufficiency in strength in the direction of a shaft center of this part, which is generated through the opening part in the circumferential direction, is eliminated through the provisional protrusion. |
