Reifenhäuser Gmbh & Co. Maschinenfabrik

Wilhelm Predohl

Hans Reifenhauser

Paul Reitemeyer

Heinz Beisemann

Process for producing a plastic foil of thermoplastic material

The process for making a thermoplastic foil involves the use of a wide-outlet or long-slit die which has at least one outlet-gap-defining adjustable die lip, an opposing gap-bounding lip and a group of piezotranslators distributed over the length of the outlet-gap-defining adjustable die lip, each of which is part of a control loop, acts as a positioning member and is associated with an individual section of an outlet-gap-defining adjustable die lip. At least one actual value of the foil thickness of the thermoplastic foil formed is measured with a measuring device and is fed to a controlling processor. Each of the piezotranslators is controlled by a controlling processor with a controlling variable. In the controlling processor a distribution control variable which is generated by a thickness variation or error is generated by a control variable deviating from a setpoint value and the distribution control variable is fed to individual piezotranslators from the controlling processor according to a distribution function which distributes the thickness errors over the length of the adjustable outlet-gap-defining adjustable die lip.

Process and apparatus for making a thermoplastic foil

The apparatus for continuous extrusion of a plastic laminate has at least two extrusion screw presses, an accumulator block, a transition unit, and an output die, from which the plastic laminate product is extruded. The accumulator block has a combining channel or canal therein which is fed by the extrusion screw presses. This combining canal is connected by way of the transition unit to the output die. The combining canal preferably has a rectangular cross section with rounded corners and at its upstream end is directly connected to a first extrusion screw press by way of a connecting canal coaxial with the combining canal. Downstreamwards below the connecting canal is found at least one input metering slot connected to the combining canal at one end and through a connecting apparatus at its other end to an additional extrusion screw press, this input metering slot lying between an input plate and an adjusting bar guided in an adjusting bar recess. The input metering slot extends over a rectangular side of the rectangular cross section combining canal, is directed slantingly downstreamwards, and opens into the combining canal. The adjusting bar has an adjustable beveled portion fitting into the combining canal and is adjustable perpendicular to the input metering slot in the adjusting bar recess so as to meter the flow of thermoplastic material from the additional extrusion screw press.

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Hennef-Bool, Germany

Wilhelm Predohl