| 摘要 |
PURPOSE:To reduce the residual stress generated in the juncture between a pressure pipe and an extension pipe by joining mechanically the inside and outside rings of both pipes from the inside by means of a roll joint device consisting of a combination rollers having different taper angles. CONSTITUTION:The taper angle alpham of a roller 6 is made half the taper angle alpha of a mandrel 7 so that the roller contacts in parallel with the inside surface of a pipe. The taper angle alpha'm of a roller 5 is made smaller than alpham, by which the diametral displacement of the roller 5 is made smaller than the diametral displacement of the roller 6. The residual stress generated in the pressure pipe is thus reduced and the reliability of the roll joint part is improved without executing local stress relief annealing. |
