Implementing an Accurate, Reliable Measurement System for Improving Mass Flow Automatic Gauge Control in Rolling Mills and Related Processes

摘要

Cold rolling mills in steel production plants take hot band material from the hot mill and roll it to the correct thickness and flatness. Most cold rolling mills use Mass Flow Automatic Gauge Control (MFAGC) to control the mill's rolling force and speed to obtain high-quality steel within the thickness specifications. It is critical to control the gauge or thickness of the cold-rolled steel strip for end-user requirements. Automobile manufacturers stamping car body parts depend on the steel to be within specified thickness tolerances when making high-quality parts. The steel might tear or have less than the specified strength if the steel is too thin, and the mold used to stamp out body parts will have premature wear if the steel is too thick. Stamping molds are very expensive to replace. Obtaining accurate gauge control in cold rolling mills has become more and more difficult as mill speeds increase and manufacturers work to reduce the thickness of metals, and tolerance get tighter. Traditionally, mechanical contact measurement devices (also known as mechanical contact encoders) have been used to measure the strip speed. But, mechanical contact measurement devices indirectly measure the speed of the strip and are subject to measurement errors due to slippage. Today, modern rolling mills are adopting non-contact laser gauges, such as the LaserSpeed length and speed gauge, to directly measure the strip speed in MFAGC applications. This new generation of laser-based gauge provides high measurement accuracy and high performance, and eliminates those measurement errors associated with mechanical-based contact measurement devices. This non-contact technology can measure strip speeds with ±0.05% accuracy and +/-0.02% repeatability, and without making contact with the product. It has no moving parts, eliminates all slippage errors, and is permanently calibrated.