Control for wire coating line

Abstract

A control is provided for a wire coating line which includes means for driving wire along a path at controllable speed while coating it with plastic extruded at a controlled rate and temperature, and cooling means are located at a controllable distance from the coating means to solidify the plastic. The controllable factors affect both the capacitance and diameter of the wire produced. The control allows the line to be run in accord with stored digital values for the matters to be controlled. Closed loop control is provided because the relevant factors of line operation are measured, the analogue measurements converted to digital values and compared with the stored values to produce a control signal which has the effect of reducing the differences between a desired and measured line condition as represented by the digital values compared. Closed loop control is also provided for control of the line to produce desired capacitance or diameter values in the coated wire. Whichever of capacitance or diameter is used as the basis for line control is measured and provided as a digital value to the control. This digital value is compared to a stored digital value representative of the desired capacitance or diameter. The results of the comparison is used to update the stored digital value for an operating condition of the line so that the parameter is altered to provide an operating condition which brings the capacitance or diameter closer to the desired value.