| 摘要 |
PURPOSE:To manufacture continuously a pipe having worked inner surface, smooth outer surface, and accurate outer diameter by providing a radial reduction and an inner surface working to the pipe by pressing the pipe at the spot of a grooved plug connected to a floating plug and passing it through a drawing die successively. CONSTITUTION:A grooved plug 34 for working inner surface is connected freely rotatably to a floating plug 21 used for radially reducing a metallic pipe 1 in cooperation with the 1st drawing die 2, to hold the pipe 1 at a prescribed position in the pipe 1 reduced by the die 2. Next, at the spot where the plug 34 is positioned; the pipe 1 which is passing through the spot, is reduced by plural rolls 32, which revolve in a planetary-revolving state while contacting with the outer peripheral surface of pipe 1, of a pressing device 3 attached to a rotary head 31 through a claw 33, and is also pressed against the plug 34 to work the inner surface in order to form the groove or projection 12. The pipe 1 is successively passed through the 2nd drawing die 4, to obtain a thin-walled pipe 11 having worked inner surface and excellent quality without being restricted by its length. |
