GB1439807A - Control of multilayer sheet production such as in the manufac ture of pneumatic tyres - Google Patents

Abstract

1439807 Automatic control of coating process INDUSTRIAL NUCLEONICS CORP 12 June 1973 [12 June 1972(3)] 27980/73 Heading G3R A multi-layer web, such as tyre material, is produced by applying first and second layers on to opposite sides of a substrate. The thickness of the first layer is controlled in response to measurement of the first layer before its application, and the thickness of the second layer is controlled in response to measurements of the first layer and of the thickness of the formed web. As shown in Fig. 1, a four-roll tyre calender applies top and bottom layers 8, 9 of rubber derived from banks 6, 7 on to a web of tyre cord 5 to produce a composite sheet 10. A single point radiation backscatter gauge 12 measures the thickness of the bottom layer 9, compares it with a target value in a comparator 42, and an error signal e BOT is fed to a bottom layer thickness controller 38 which adjusts the position of calender roll 4 in relation to the adjacent roll 3. The thickness of the composite web 10 is measured by a transverse scanning radiation transmission gauge 13 connected to a comparator 50 which also receives a total thickness target value and forms an error signal e TOTAL. The error signals are combined in a difference circuit 30 to form a third error signal eTOP which is used to control the position of calender roll 1, and thereby regulate the thickness of the top layer and the composite web 10. In a modification, Fig. 2 (not shown), the actual thickness measurements from gauges 12, 13 are combined and the result compared with a target value for the thickness of the top layer 8 and cord layer 5 to produce the control signal for the calendar roll 1. In order to ensure that the guages operate on corresponding portions of the web, a speed measuring device may be associated with calender roll 3 enabling a computer to provide a delay between the gauge output signals, which are to be combined, Figs. 3, 4 (not shown). The system may also be adapted for controlling the transverse profiles of the composite web and the bottom layer, Figs. 6A, 6B (not shown). In this case, at least two single point gauges are associated with the roll 3 and average thickness values are. calculated for different zones across the web. Integration and curve-fitting techniques are employed, and profile adjustments are effected by roll-bending.