Kmw Aktiebolag

Karl J Andersson

A control system for controlling a multilayer headbox for a paper machine, which headbox there are three channels converging in the direction of flow and through which stock is conducted from separate inlets to discharge slots at the slice opening for discharge of layer-forming stock jets. Each channel is connected by a feed pipeline for stock supply by means of a motor-driven pump, the speeds of which are controlled by individual speed regulator units. The control system includes a first controller, which emits an output signal as a function of a possible deviation of an actual value of the pressure of the stocks inside the headbox from a setpoint for the pressure, which output signal is transmitted to all speed regulator units in order to regulate the speeds of the motors synchronously and, by means of the pumps, to alter synchronously the stock supply to the channels. The control system additionally comprises ultrasonic transducer means arranged in proximity to the slice opening in order to obtain information about the distance between two channel-forming surfaces in respective channels, which distance information is transmitted to an electronic measuring unit connected to the transducer means and also two controllers, which each receive a measurement signal from the electronic measuring unit representing an actual distance value obtained and which compare this actual distance value with a setpoint and, in response to a possible deviation, emit an output signal to the speed regulator unit for the motor which regulates the stock supply to the channel in question.

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Karlstad, Sweden

Karl J Andersson