FORMATION OF FEMALE SCREW AND DEVICE THEREFOR, AND FORMED PRODUCT

摘要

PROBLEM TO BE SOLVED: To improve production efficiency of a female screw. SOLUTION: A prepared hole 24 and a gathering part 26 of excess thickness located in a surrounding wall around the prepared hole 24 are formed in a work 4. By opening the opening-closing tap 7 in the direction of radius of the prepared hole 24 under the condition that an opening-closing tap 7 in closed state is inserted into the direction parallel to the axis line, a screw thread part 12 of the opening-closing tap 7 is transferred to the prepared hole 24 to form a female screw 5, and at the same time an excess thickness generated by the transfer of the screw thread part 12 is made to escape into the gathering part 26 of excess thickness.