Patent ID: 6089068
Filing Date: 2000-07-18
Classification: B21C,B21H,B21K,B23P

Abstract:
A method of manufacturing a shaft having a fluid flow passage below a surface thereof, comprising:a first preliminary step of forming in a surface of a columnar-shaped base material thread grooves having a substantially V-shaped cross section,a second preliminary step, which is effected subsequent to the first preliminary step, of expanding the thread grooves having the substantially V-shaped cross section to form thread grooves having a substantially U-shaped cross section and whose roots are arcuate, anda finishing step of compressing crests of thread ridges between adjacent ones of the thread grooves in a direction in which the base material is reduced in diameter, to perform plastic deformation of the crests and join the deformed crests to one another to form a spiral-shaped closed space which communicates spaces in the thread grooves.