GB1176566A - Method and Apparatus for Extruding Plastics Material - Google Patents

Abstract

1,176,566. Automatic control of extrusion equipment. POLYPLASTE H. ROLF SPRANGER K.G. 27 June, 1967, No. 29559/67. Heading B5A. [Also in Divisions B8, D1 and G3] Differences in the speeds of rotation of two rolls 3 and 5, the former situated at the nozzle of an extrusion machine 1 and the latter forming with a driven feed roll 6 a haul-off mechanism for an extruded plastics filament 2, create error signals in a comparator circuit 9 which are fed to an amplifier 10 and thence to an actuator 11 which adjusts the speed of feed roll 6 to changes in the rate of extrusion. Between the haul-off mechanism and a take-up mechanism is a control arm 15 which adjusts the rate of working of a driving unit 14 for the take-up mechanism in response to changes in speed of movement of the filament. Slippage of filament 2 on rolls 3 and 5 is compensated for by a control arm 12 which adjusts the reference level in comparator circuit 9, and between the rolls, the filament passes through a cooling bath 4. As shown, the take-up mechanism comprises a bobbin 7 which is one of four such mounted on an indexable spider (16), Fig. 2 (not shown), the arrangement being such that when a bobbin is full the filament is cut by a blade (20), the full bobbin is brought above an envelope (22) and dropped into it, and the wrapped package is weighed by mechanism (23) and delivered to a conveyer (25). Filament 2 is transferred to an empty bobbin by a gripper (19) and a variable speed transmission 17 compensates for the increase in diameter of the winding on the bobbin as this is filled. A building motion device (13) is provided. Generally, the electrical system may be replaced by an hydraulic and/or pneumatic servo system and alternative take-up mechanisms may comprise slitting, transverse cutting, milling or punching units.