Direct and Parallel Measurement

Direct measurement
Direct measurement means to measure the flatness as early as possible after the start of rilling and then continuously and without any delay measure with a high measurement frequency. This is a must in order for the flatness control system to minimize those parts of the head and tail ends of the strip that are outside tolerance limits. The Stressometer system measures the flatness directly at the start of rolling. A complete flatness reading is available within the first 1/4 of a roll revolution. The measurement is taken four times per revolution, even during the acceleration phase, which means step responses down to 150 mm of the strip length.

Parallel measurement
Parallel measurement means that all measurement readings are taken simultaneously and in parallel across the strip width. The measurements are taken at the same instant and thereby at the same tension. This is important because the strip tension varies during rolling of the strip. All disturbances in the strip tension regardless if they come from the workrolls or the coiler, will affect all sensors in the same way and therefore not affect the flatness measurement. Parallel measurement is therefore essential in order to eliminate interference from workrolls, deflectors rolls and coilers.