| 摘要 |
PURPOSE:To manufacture a long inside surface grooved pipe easily, continously and with high productivity, by pressing a pipe material against a rotatable grooved plug placed in the pipe material, by plural rolls having a grooved roll surface, compressing it, and drawing it down. CONSTITUTION:A small-diameter pipe 36 is obtained by drawing down a pipe material 18 between a supporting die 10 and a supporting plug 20. In the small- diameter pipe 36, a prescribed grooved plug 28 is placed by supporting it so as to be rotatable by a bearing 32 through a connecting rod 30. Also, on both upper and lower side positions opposed to the grooved plug 28, a pair of rolls 34, 34 which are rotatable in the advancing direction of the pipe material 18 are placed. On the outside circumferential surface of the roll 34, a concave surface grooved roll surface 38 whose radius of curvature is almost same as that of the outside circumferential surface of the small diameter pipe 36 is formed. When the pipe material 18 is drawn in the direction as indicated with an arrow F, rolling down these rolls 34, 34, a spiral groove 31 corresponding to the groove of the grooved plug 28 is transferred to the inside surface of the pipe material 18. |
