| 摘要 |
Regulator for a thin film blown tubing extruder maintains prodn. control, the plant having a ring nozzle, continuous air flow internal cooling for the tubing, outlet for the used air, air urrent control, and optical sensor, devices for the position of the tubing. Devices have >=2 sensors and they alter an electrical output signal according to the wall position and any deviations from its nominal position; a controller produces a corresponding difference signal according to deviations and this signal is unaffected by cross-movement of the tubing unless the tubing circumference changes; the difference signal regulates a valve for the continuous air supply by producing a reduced tubing circumference from a reduced difference signal. Simple method is provided for maintaining constant circumference of tubing to narrow tolerances but without actually touching the material. |
