초록 ▼

A thermal actuator system controls the position of a moveable die lip (32, 34) on a flat film extruder die (30) to control the gauge of the extruded plastic film, and includes thermal actuators each of which has an outer thermal bolt (70) and an inner bolt (80) extending through the outer bolt. The

A thermal actuator system controls the position of a moveable die lip (32, 34) on a flat film extruder die (30) to control the gauge of the extruded plastic film, and includes thermal actuators each of which has an outer thermal bolt (70) and an inner bolt (80) extending through the outer bolt. The inner and outer bolts have outer ends which are connected together, while the outer bolt is connected to the die body and the inner bolt has an operative end connected to a die lip. An air passage (90) is formed between the inner and outer bolts and through which air is applied for cooling the inner bolt with respect to the outer bolt. Thermal expansion of the outer bolt is controlled by an external heater (75) mounted on the outer bolt.

대표청구항 ▼

[ I claim:] [6.] The method of controlling the extrusion gap of a slot type film extruding die in which at least one longitudinally extending external die lip is mounted to a planar exterior surface of the body of the die defining a surface plane and is moveable along such surface plane for adjustin

[ I claim:] [6.] The method of controlling the extrusion gap of a slot type film extruding die in which at least one longitudinally extending external die lip is mounted to a planar exterior surface of the body of the die defining a surface plane and is moveable along such surface plane for adjusting the extrusion gap, and which die lip may be bent parallel to said plane for adjusting variations in the gauge of the film extruded from said die comprising the steps of using differential expansion bolt actuators in which an outer annular bolt is heated and an inner bolt is cooled by air flow along the length of the space between said bolts thereby providing a variable output force between the outer annular bolt and the inner bolt, applying a plurality of such actuators along the longitudinal length of said external die lip in mutually and relatively uniformly spaced relation to each other, with the output force of each of such actuators directed in a common plane which common plane is parallel to the surface plane, applying a relatively constant flow of cooling air along the length of said inner bolt, and controlling the relative heating and cooling of said actuators in accordance with the film guage desired at the position of said die lip represented by such actuator, to cause adjusting movement of said die lip as caused by said bending of said die lip.