DEFORMED STEEL BAR HAVING JOINT AND USED FOR REINFORCED CONCRETE, THE JOINT, AND FORMING METHOD FOR JOINT OF DEFORMED STEEL BAR USED FOR REINFORCED CONCRETE

摘要

PROBLEM TO BE SOLVED: To increase the strength of the joint of a deformed steel bar for reinforced concrete over the strength of a base material without thickening the joint and the jointed part of the deformed steel bar. ;SOLUTION: Only the surface projections 3 and 3a of the end of a deformed steel bar 1 for reinforced concrete are deformed to a flat state at a cold plastic working process, and the processed ends 6 and 6a are formed to have an approximately cylindrical shape of approximately the same diameter as the base 2 of the deformed steel bar 1. Then, external threads 7 and 7a are formed on the processed ends 6 and 6a at a cold plastic working process via thread rolling for use as joints 4 and 4a. In this case, the joints 4 and 4a are jointed to each other and hardened via the cold plastic deformation of the surface projections 3 and 3a, and the cold formation of the external threads 7 and 7a. The strength of the joints 4 and 4a is thereby increased over base material strength without being thickened. According to this construction, the surface projections 3 and 3a can be plastically deformed and the external threads 7 and 7a can be formed under a relatively small force, and the strength of the joints 4 and 4a more than the base material strength becomes available without thickening the joints 4 and 4a.;COPYRIGHT: (C)1998,JPO