| 摘要 |
PURPOSE:To make it possible to extrude two or more kinds of tubular bodies different in wall thickness at low cost by a method wherein the gap size at the outlet portion of resin flow path is controlled by controlling the screwing-in depth of a tension bar to an inner male die approach part by rotating the tension bar. CONSTITUTION:When the shaping of parison C1 having thick wall thickness is intended, a movable tension bar 23 is rotated to the direction so as to make its screwing-in depth to a fixed tension bar 22 longer. As a result, an inner male die land part 212 is retreatingly shifted to the direction opposite to the extrusion direction in interlocking with the movable tension bar 23 so as to part the conical surface 212a of the inner male die land part 212 from the conical surface 122a of an outer die land part 122 in order to enlarge the gap size of the outlet portion of resin path 3. Thus, the parison C1 having thick wall thickness is shaped. When the shaping of parison C2 having thin wall thickness is intended, the movable tension bar 23 is rotated so as to make its screwing-in depth to the fixed tension bar 22 shorter. As a result, the gap size of the outlet portion of the resin path 3 is contracted, resulting in shaping the parison C2 having thin wall thickness. Thus, two or more kinds of tubular bodies different in wall thickness can be extruded. |
