| 摘要 |
<p>PURPOSE:A mandrel for molding plastic spiral corrugated pipes, capable of reducing frictional force, facilitating mold release, and increasing the extrusion speed, comprising a molding part and a specific holding part. CONSTITUTION:A plastic is extruded by using the mandrel 5 having the molding part A, wherein only the outside diameter of the corrugation shape is gradually decreased as in the conventioned mandrel to mold the plastic 6, and the holding part B, wherein the width of the ridge is narrowed and the groove is flattened so that the height of the ridge and depth of the groove may be in agreement with the inner groove and ridge of the final product. The pipe is then cooled to decrease the frictional force between the spiral pipe 7 and the mandrel 5.</p> |
