| 摘要 |
PURPOSE:To obtain a titled flat sheath whose section shape is uniform by forming a cylindrical pipe body obtained welding continuously a side edge part of a cylindrical body formed gradually from a band-like plate, to a grooved pipe body having a groove on the outside circumferential part, forming it gradually to an elliptical shape whose section is flat, and also forming a spiral groove on the outside circumferential part. CONSTITUTION:A band-like plate 1 is made to pass through between rolls 4a, 4b of a forming roll 4 whose forming surface is curved, and the band-like plate 1 is curved continuously along its longitudinal direction. Subsequently, this band-like plate 1 is formed so that the section becomes roughly semicircular, by rolls 5a, 5b of a forming roll 5, and also both its side edge pats are joined through forming rolls 6, 7, by which a cylindrical pipe body 14 is obtained. Next, a joint part 1 of the pipe body 14 is welded 10, and thereafter, a pipe body 1a is led to a grooving means 11. Subsequently, a grooved pipe body 2 is obtained continuously by forming a spiral groove 2a on the outside circumference of the pipe body 1a by the means 11. Thereafter, the pipe body 2 is made to pass through sucessively forming rolls 18-21, flatted gradually, and an object titled flat sheath is obtained. |
