| 摘要 |
<p>A synthetic resin tube having thick wall portions extending radially outwardly and thin wall portions formed with a plurality of perforations. The thick and thin wall portions are alternately arranged along the longitudinal direction of the tube. Each of the thin wall portions is further formed with an annular inwardly bent portion. The method for producing such a tube comprises the steps of periodically varying an extrusion working space defined between movable and stationary dies, and installing a sizing die to regulate an inner peripheral surface of the extruded tube, while pre-cooling an outer surface of the tube by shower or mist and inner surface thereof by pressurized air. The perforations are formed upon partial contact between the movable and stationary dies, and the annular bent portion is formed by the peripheral speed differential between first and second sets of rollers, both being adapted to drive the precooled extruded tube.</p> |
