| 摘要 |
PURPOSE:To manufacture with high productivity a heat transmission pipe of a holed helical fin type without wasting a material, by making a notch at a suitable pitch on a band material, taper-rolling it, curl-working it and winding it round a pipe. CONSTITUTION:A linear notch is made at a suitable pitch by a press 1, etc. to a part or one area of a band material 10 of a base material of a fin, it is made to pass through between a pair of rolls 2, 3, and a flat notched band material is obtained. The band material 10 is guided by a suitable number of guide rolls 4, 5 and 6 and is led into a pair of rolling rolls 7, 8, and in a part 7a of a comparatively small diameter of the rolling roll 7, rolling force becomes smaller than in other part, and a part 7b of both ends of the roll 7 has a larger diameter than said part 7a, therefore, regular rolling force operates on the part 7b of both ends. Therefore, a hole is formed by expanding the notch. Subsequently, said material is curled continuously, is wound around a pipe, and it becomes a heat transmission pipe provided with a helical fin. |
