a detail for designing tilted lifter mechanism need to be known, for inner side core-pulling, top of the tilted slide should be 0.05—0.1mm lower than the end plate if core, since during the protruding, the tilted lifter performs core-pulling action which moves innerside. To prevent the radial interference from bottom of the plastic part on core-pulling, the bottom must be higher than the top of the mechanism, and meanwhile, opposite to the moving range S of the radial around the mechanism there must be provided with a S1 which is larger than the distance of S so that such barrier as circular bead can form to avoid interference on core-pulling, i.e S1>S.