| 摘要 |
PURPOSE:To reduce the friction resistance to be applied on a pipe and to work at high speed even a small diameter thin pipe by rolling between it and a metallic pipe, using plural balls instead of a planetary rolling roll. CONSTITUTION:The ball 15 which is a rotation work member is arranged so as to contact and roll respectively to the outer periphery of the metallic pipe 1 in the opposing position to the plug 5 with groove and the inner peripheral rolling face 16 of a rotary head 17. The rotary head 17 is rotated in the direction of arrow mark 11 when the metallic pipe 1 is drawn and driven in the direction of the arrow mark 2, and the ball 15 shrinks the metallic pipe 1 and forms an inner face groove 14 as well on the inner face of the pipe with revolving with its rotation by its rolling along the both of the inner peripheral rolling face 16 of the rotary head 17 and the outer peripheral face of the metallic pipe 1 accordingly.
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