US 4,903,517 AGranted

Method of and apparatus for regulating the operation of calenders and like machines

AssigneeKleinewefers GmbH

InventorsRolf Van Haag, Rainer Schmidt

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Abstract

The operation of a calender or a like machine with at least one pair of rolls which define an elongated nip and wherein at least one of the rolls is a so-called bending compensation roll is regulated by a computer which transmits signals to adjustable pressure regulating valves in conduits serving to admit pressurized fluid to a plurality of actuators (such as hydrostatic bearing elements and hydraulic cylinder and piston units for the bending compensation roll) which can alter the load parameter (such as the line load or the compressive strain) in discrete zones of the nip. The computer has inputs for signals which indicate the temperature in the nip, for signals which indicate the characteristics of the web that is advanced through the nip, and for signals from a memory for a pressure reaction matrix. The pressure of fluid is regulated in such a way that changes of the actual value of load parameter in a selected zone of the nip do not entail any changes, or do not entail any appreciable changes, in other zones of the nip.

Claims25

Dependent claims

A method of regulating the operation of a calender or an analogous machine with at least two neighboring rolls which define an elongated nip and the load parameters, such as the line load or the compressive strain, in a plurality of different longitudinally spaced apart zones of the nip are controlled by discrete actuators which receive a fluid medium at a variable pressure so that they can alter the parameters in the corresponding zones of the nip, and wherein a change to bring about a deviation of the parameter in one of the zones from a reference value tends to entail changes of parameters in other zones of the nip, comprising the steps of establishing at least one pressure reaction matrix with elements which denote those deviations of actual values of parameters for said other zones from reference values which take place in response to a change of parameter in the one zone;

utilizing said matrix to individually calculate seriatim for the actuator for each of said other zones that pressure variation which at least partially compensates for departure of actual value of the parameter in the respective zone from the reference value and to further calculate the resulting change of parameter for each other zone until an error function which is dependent upon the differences between the actual values of parameters and the reference values is within a predetermined range of tolerances;
and varying the pressure of fluid for the actuators in accordance with the sum of variations which are calculated for the respective actuators.

Apparatus for regulating the operation of a calender or an analogous machine wherein at least two neighboring rolls define an elongated nip and at least one of the rolls is deformable by a plurality of discrete actuators, one for each of a plurality of different zones of the nip, and wherein the actuators are connected with a source of pressurized fluid and the pressure of fluid is variable by signal-responsive regulating devices to thereby alter the load parameters, such as the line load or the compressive strain in the respective zones of the nip, comprising computer means having first input means for signals denoting reference values of the load parameters and second input means;

and a memory arranged to store at least one pressure reaction matrix and connected with said second input means, said matrix having elements indicative of those deviations of actual values of parameters for said zones from reference values which take place in response to a change of fluid pressure for one of said actuators, said computer means having signal transmitting output means connected with said regulating devices.

Dependencies are inferred from the claim text.