| 摘要 |
<p>PURPOSE:To manufacture continuously and efficiently synthetic resin pipe in which helix rib is not formed from the middle of the pipe to other end by turning a plate to the peripheral direction by a position adjust means and switching in a state that a recessed groove conforms with a notch and in a state that an outlet end face of the recessed groove is blocked at a part where the notch of the plate is not provided. CONSTITUTION:In an extrusion mold, a synthetic resin pipe having an internal helix rib with a helix rib corresponding to a recessed groove 23c formed on the inner face is extruded from an outlet of a mold 2. There is provided a disk-like plate 27 having a notch 27a with an outer diameter about the same as maximum diameter of cores 22, 23 and with about the same size or a little larger size than that of the recessed groove 23c formed on the periphery at the same pitch as that of the recessed groove 23c. The plate 27 is rotatably supported by the outlet end face of the cores 22, 23 in a state that the center axis is conformed with the axial center of the cores 22, 23. A position adjust means 28 for turning the plate 27 in the middle of the extrusion molding to a desired angle is provided so as to deviate the positional relationship in the peripheral direction of the recessed groove 23c and the notch 27a.</p> |
