Industrial Nucleonics Corporation

Robert Lee Heiks

John Francis Donoghue

Ronald W Brand

Charles Ray Rich

Dan Edward Forney

Bruce A Huber

Robert Eugene McCall

Richard A Forbes

Gerald A Lasson

Thickness of a sheet being produced by an extruder is controlled in response to measurements of: sheet thickness, the speed at which material is fed through a screw of the extruder, as determined by screw speed, and the speed with which material is taken away from the extruder, as determined by sheet speed. Measured thickness is compared with a setpoint for sheet thickness and a determination is made as to whether the thickness is in a predetermined, deadband region relative to the setpoint, or if the sheet is out of the deadband because it is excessively thin or excessively thick. In response to the sheet thickness being in the deadband region, the screw speed is changed in response to a signal indicative of the product of sheet speed error and rate of change of screw speed with respect to sheet speed. Sheet speed is controlled by multiplying sheet speed error by a predetermined constant. In response to the sheet being excessively thin, screw speed, if it has not reached a maximum value, is changed by multiplying sheet thickness error by rate of change of screw speed with respect to sheet thickness; if the screw speed has reached a maximum value, sheet speed is changed by multiplying the thickness error by the rate of change of sheet speed with respect to thickness. In response to the sheet being excessively thick outside of the deadband region and the sheet speed has not reached a predetermined maximum, line speed is changed by multiplying sheet thickness error by the rate of change of sheet speed with respect to sheet thickness; if the line speed has reached the predetermined maximum, screw speed is changed in response to an indication of the product of sheet thickness error and rate of change of screw speed with respect to sheet thickness. The various rates of change are calculated from an equation which models sheet thickness, T, screw speed, V.sub.S, and sheet speed, V.sub.L, in accordance with: ##EQU1## where: A, B AND C ARE PREDETERMINED CONSTANTS DETERMINED FOR EACH EXTRUDER MACHINE AND ASSOCIATED APPARATUS.

Extruder controller

A process monitoring and control system is provided for use in a tire calendering system producing a strip of rubber tire material comprising a layer of tire cord laminated between first and second layers of rubber. In a preferred embodiment, the thickness of the first rubber layer is measured by a single point radiation backscatter gauge at a point prior to its lamination with the tire cord and second layer. The thickness of the first layer is controlled to a desired target by means of a control loop including the single point gauge. The total thickness of the combined layers is measured at the calender output by a total thickness gauge. Gauge coordination means, including a delay means, are provided whereby measurements of the thickness of the first layer and of the combined strip are derived over the same longitudinal portion of the strip. Means are included, responsive to the coordinated measurements, to control the thickness of the second layer to maintain the total thickness of the strip at a desired total thickness target, in such a way as to eliminate any error in the thickness of the first layer as a factor affecting the control of total thickness. In this manner, the desired total thickness of the calendered material and the desired position of the tire cord between the first and second rubber layers are maintained.

Process control

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Columbus, OH, United States of America

Robert Lee Heiks