MANUFACTURE OF INNER DIAMETER HELICAL PARTS AND DIE DEVICE FOR STRAIGHTENING THE PARTS

摘要

PROBLEM TO BE SOLVED: To rotate a sintered material without any hindrance by mutually surely stopping the rotation of a core rod, a punch and a die. SOLUTION: On the outer peripheral surface of a core rod 16 in a die device for straightening, a helical serration 17 engaged with a helical serration 2 on the inner peripheral surface of a sintered material 1 is arranged and the sintered material 1 is rotated at the time of straightening. On the die 12, a positioning piece 3 energized with a spring 39 is arranged and the sintered material 1 is positioned in the rotating direction by engaging the positioning piece 38 with a recessed groove 3 on the outer peripheral surface of the sintered material 1. The core rod 16 and a lower punch 23 are locked to the rotation by fitting an almost rectangule-shaped rotation locking part 18 formed on the outer peripheral surface of the core rod 16 to a rotation-locking hole 24 in the lower punch 23. Further, the lower punch 23 and the die 12 are locked to the rotation by engaging a projecting line 25 on the outer peripheral surface of the lower punch 23 with the recessed groove 14 on the inner peripheral surface of the die 12.