Manufacture of female member

PURPOSE: To improve the productivity and to reduce the cost by manufacturing a joint screw reinforced steel. CONSTITUTION: A screwed projection is formed in a working part 11 of a core metal. The working part 11 is loosely inserted into a through-hole 21 in a base stock 20 and this is set to a lower die 31 in a pressing device. The base stock 20 is plastically deformed by pressing with the lower die 3 and an upper die 32 to form the cross sectional shape in the outer peripheral surface of the base stock 20 to a hexagon. At the same time, the inner peripheral surface of the through-hole 21 is brought into pressurized contact with the outer peripheral surface of the working part 11 to form a screwed groove on the inner peripheral surface of the through-hole 21. This base stock 20 is laid on a table 41 in the other pressing device, and by pressing with a hammer 42, a gap 50 is formed between the screwed groove in the base stock 20 and the screwed projection in the working part 11. By forming the gap 50, the working part 11 can be made to rotate to the base stock 20, and the working part 11 can be pulled out from the base stock 20. COPYRIGHT: (C)1993,JPO&Japio