LOCK BOLT OF HIGH STRENGTH STEEL PIPE AND METHOD OF MANUFACTURING THE SAME

摘要

A lock bolt of a high strength steel pipe, wherein an expansion type lock bolt body is formed of a deformed pipe manufactured by using, as a raw material, a high tension steel plate having a tensile strength of 490 to 640 N/mm<2>, an elongation of 20% or more, and a plate thickness of 1.8 to 2.3 mm and having a single or a plurality of recessed parts extending in the axial direction of the deformed pipe. Since the high tension steel plate is used in the lock bolt, sufficient strength can be secured for the lock bolt though the steel plate is thin, and cracking due to stains introduced in a molding process, a both end shrinkage process, and a pressurizing/expanding process can be suppressed. Since an expansion start pressure when a pressurized fluid is press-fitted and inflated is also low, a time in which the expansion/deformation is completed can be shortened and workability can also be improved.