Controlling the synchronicity of piston-cylinder units for contacting a press roll with a guide roll, e.g. in a plastic film stretching unit, involves using separate hydraulic lines to balance the contact pressure at a set value

摘要

A method for controlling the synchronism of piston-cylinder units (PCU) (6, 7) for applying a press roll (4) to a material guide roll (3) (especially in thermoplastic film stretching units) by advancing (4) and establishing contact between the two rolls at a set pressure, in which the PCU are actuated via separate hydraulic pressure lines (8, 9) in such a way that roll (4) is advanced parallel to the axis of (3) until there is a hydraulic pressure balance between (6) and (7) and the set pressure is applied over the entire width of roll (4). An independent claim is included for a device for the above method, especially in a thermoplastic film stretching unit, with a press roll (4) mounted on bearings (5) moveably connected to a fixed point (1) on the system, and PCU (6, 7) between (5) and (1) which are connected via hydraulic pressure lines (8, 9) to a metering cylinder unit (MCU) (15) fed with compressed air, in which (a) the MCU (15) is designed so that the piston of each PCU follows the same path when the MCU is actuated, (b) the hydraulic lines (8, 9) are connected together via at least one pressure compensation line (10) in which (c) there is at least one stop valve (10.1) which is connected (for signal transmission) to a control unit (11), (d) there is/are sensor(s) (12) for measuring the distance and/or pressure between the rolls (4) and (3), and (e) the sensor(s) (12) is/are connected to the control unit (11).