| 摘要 |
PURPOSE:To heighten further the high buckling strength of a pipe by a method in which the cross section-shape of the pipe is made uncircular uniformly, and a synthetic resin bandlike object is spirally wound on said pipe, thereby constituting an uncircular pipe. CONSTITUTION:The rotating position of a rotary mandrel 7 is detected by a position- sensor 30, and the controlling circuit 31 which received the signal of detected position commands the rotating speed which makes the speed of the rotary mandrel 7 into prescribed value to a servo motor 27. Simultaneously, suitable rotation is commanded to a servo motor 15, whereby a pinion 17 is run on a rail rack 19, and a die 12 and a pressing roll 11 are kept on the surface of the rotary mandrel 7 in equal distance. Further, the controlling circuit 31 commands the rotation of equal speed to the servo motor 20, and the bandlike object 5 of synthetic resin is spirally wound on the rotary mandrel 7, whereby the synthetic resin pipe 1 which has oval cross section corresponding to the cross section-shape of the rotary mandrel 7 i.e. to the oval shape, is produced. The oval synthetic resin ring 1 has a uniform plate-thickness at each part of its outer periphery and high buckling strength even in the direction of the line of upsides. |
