Tubular sheet wall thickness regulation system - measures thickness at successive positions in lengthwise direction round periphery

摘要

The system regulates the wall thickness of a tube of sheet material extruded from the annular opening of a head and pulled at adjustable speed by a haulage mechanism. Temperatures in sectors around the head periphery are regulated dependent on wall thicknesses in the respective sectors, and haulage speed dependent on variation in wall thickness from the desired value. At each position on the periphery, thickness is measured at several successive points in the lengthwise direction of the sheet, and from the results a mean value is calculated. From these in turn a mean value is calculated for the entire periphery, and the discrepancies from this value of the individual sectors are used to generate control signals altering their respective temperatures.