| 摘要 |
PURPOSE:To manufacture tubes of respective sizes having bow-shaped cross sections simultaneously and continuously, by inserting round tubes between a roller having bow-shaped grooves and a cylindrical roller. CONSTITUTION:A cylindrical roller 1 having bow-shaped grooves and a cylindrical roller 2 are set closely and rotated, then a round tube 4 is inserted to the grooved part of the roller 1 to form a tube 3 having bow-shaped cross section continuously. Further, tubes of plural sizes having bow-shaped cross sections can be manufactured simultaneously by providing plural grooves corresponding to respective sizes to the tube 4 as shown by the figure. Further in a case that the tube 4 is standard one in length, several centimeters of both ends of the tube 4 are kept round without rolling both ends to be used for the connecting parts of joints when necessary, and a conventional round-shaped joint can be used as it is when the tube 4 is connected to other round tube. |
