Online thickness measurement
Producing calendered sheet within tolerance is subject to many interacting variables such as top and bottom coating thicknesses, rubber penetration depth, calendar speed, pressure, temperature, compound type and homogeneity, line speed and condition of the calendar rolls.
Measurement and control systems based on scanning x-ray, beta or gamma backscatter sensors and air gauging are problematic for a number of reasons. Read more
For calenders with no existing measurement system, typically sheet thickness is checked manually online by an operator using a caliper or snap gauge on one side of the sheet. However, caliper gauges are inaccurate and subject to significant gauge R&R variability.
The thickness of solid rubber sheet, coated steel cord or coated fabric ply can be measured immediately after calendaring using Sigmavision's STMS online thickness measurement system. Fixed mounted laser spot sensors are positioned across the sheet width on a purpose built frame. Any number of sensors may be used though typically three measurements are made along the left edge, centre and right edge of the sheet. For measurement of rubber gum on the calender Sigmavision's STMS3 system may be used. This comprises two Smart 3D sensors mounted on calibrated lead screw that indexes the sensors in and out depending on the sheet width. The edges of the sheet are found automatically and left and right sheet thicknesses measured directly by imaging the step down onto the calender bowl. Read more