| 摘要 |
PURPOSE: A cast stopper body with detachable inner screw part is provided to enable a stopper body on the inner circumferential surface of which screw thread is formed to be fabricated only by primary casting without secondary tapping for forming screw thread, and a method for molding the inner screw part of the cast stopper body is provided. CONSTITUTION: The cast stopper body with detachable inner screw part(42) is characterized in that a pair of screw thread non-forming parts(44) installed oppositely to each other in such a way that a certain width is maintained between the screw thread non-forming parts are formed on the inner circumferential surface of a circular stopper body(40), and a screw thread is projectingly formed along the inner circumferential surface of the circular stopper body around the screw thread non-forming parts. The method for molding the inner screw part of the cast stopper body comprises a step of inserting a core(20) for maintaining inner cross section of a molded article into depression parts(13) of metallic pattern(10), wherein the core comprises a pair of left and right unfolding elements(22,22a) on the outer circumference of which screw part is formed, and a guide pin(26) lowered and lifted with being inserted between the pair of left and right unfolding elements; a step of forming a pair of semicircular screw parts with being spaced apart from the inner wall of the molded article centering around the guide pin using the injected casting solution by injecting a casting solution into a molding space of the stopper body formed between the core and the outer wall of the metallic pattern; a guide pin separation step of preparing a moving space so that the left and right unfolding elements are moved into the inner side by moving the guide pin positioned at the center of the core after solidifying the casting solution; and a step of separating the unfolding elements from the molded article of the cast stopper body as the unfolding elements are being moved to the inner side by the moving space by moving the core inserted into the molded article to the upper side.
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