| 摘要 |
PURPOSE:To manufacture efficiently and economically a heat transmitting tube excellent in heat transmission performance by forming a skelp, having multiple lines of grooves formed in its one-side surface by hot rolling, into a tube and forming successively each groove-root corner R of the gooves into an acute angle while radially reducing the tube by cold drawing. CONSTITUTION:After heating a skelp 1 by passing it through the inside of an induction coil 4 of a high frequency induction heating device; multiple lines of grooves 2 are formed in the one-side surface of the skelp 1 along the flow direction of the skelp 1 by a mill provided with a grooved form-rolling roll 6 and a flat roll 10, and then the skelp 1 is passed through an electric welded pipe manufacturing installation 7 to obtain a tube 8 having many grooves 2 parallel to the tube axis in its inner surface. Next, the tube 8 is radially reduced by cold drawing it with the aids of dies 9,9' and, at the same time, each groove-root corner RB part of said grooves 2 is formed into an acute angle by a stress acting on the inner surface of tube 8 at the time of its reduction rolling, to obtain a heat transmitting tube 8 excellent in heat transmission performance. |
