Patent ID: 11774013

Abstract:
Formed in series along an axial-direction end portion of a large-diameter pipe member, in the following order from the pipe end, are: a large-diameter-pipe pipe-end expanding portion; a large-diameter-pipe reduced-diameter portion; a large-diameter-pipe bulging portion; and a tapered portion. Formed in series along an axial-direction end portion of a small-diameter-pipe member, in the following order from the pipe end, are: a small-diameter-pipe pipe-end expanding portion; a small-diameter-pipe enlarged-diameter portion; and a small-diameter-pipe bulging portion. The outer cylindrical surface of the small-diameter-pipe enlarged-diameter portion is in close contact with the inner circumferential surface of the large-diameter-pipe reduced-diameter portion; the inner cylindrical surface of the large-diameter-pipe bulging portion and the outer circumferential surface of the small-diameter-pipe pipe-end expanding portion are engaged; and the inner circumferential surface of the large-diameter-pipe pipe-end expanding portion and the outer cylindrical surface of the small-diameter-pipe bulging portion are engaged.