| 摘要 |
A large-capacity screw extruder for non-expandable resins comprises a first extruder cylinder of relatively small diameter having an inlet adjacent one end and a discharge adjacent the opposite end which discharges through a fluid pressure-tight connection to a second extruder cylinder of relatively large diameter having an extruder screw of relatively large diameter which rotates at a speed which is at most half the speed of the smaller diameter screw. The connection between the sections of the extruder is provided with an exchangeable screen changer and means are provided for sensing the pressure in the connection and for regulating the speed of the drive of the small diameter extruder screw in order to maintain selected pressure conditions. In one embodiment, the larger diameter extruder cylinder is provided with an intermediate vent to permit the venting off of gases. Both extruder cylinders are advantageously provided with means for selectively heating and cooling the cylinders during operation. With the method of the invention, unexpandable resin material is fed into the inlet hopper of the first extruder cylinder and is operated at a relatively high rotational speed to effect the melting of the resin at a very high rate by the rotation of the screw and by the addition of heat as necessary. The resin is delivered through the discharge of the first cylinder and the connection between the first and second cylinders into the second cylinder where the screw therein is rotated at a relatively low rate which is at most one half the rotational speed of the first section. The pressure between the two sections is advantageously monitored during the operation and controlled at a selected amount and the resin being treated in the second section is advantageously cooled and may also be vented. |
