An apparatus for forming by casting or molding a gifted article internally threaded hole of a

摘要

A method of casting or moulding an internally screw-threaded article comprises introducing casting or moulding material around two withdrawable flat core members which overlap within a mould cavity. The leading end face of each core member is formed with a male segment of the female screw thread to be formed in the article, the arrangement being that when the core members meet one another the two screw thead segments of the two core members are located to form two diametrally opposite segments of a male image of said female screw thread, withdrawing the core members from the mould cavity when the casting or moulding material has set and removing the cast article from the mould cavity.