Coating mass control system design for a continuous galvanizing line

The structure of a typical computer-based coating mass control system is derived which incorporates feedback and feedforward controllers based on recently developed adaptive mathematical models for the jet stripping process. Using conventional design techniques, three alternative types of feedback control algorithm are invstigated. The 'pulse-and-wait' algorithm is recommended for computer control applications due to its ease of implementation. Typical simulation results are presented for a range of strip speeds with and without errors in the model parameters. Emphasis is placed on the need to adjust some of the controller settings as a function of process conditions. A computer control system based on the previously outlined concepts has been commissioned on a modern continuous galvanizing line operating at speeds up to 170 m/min. Typical results are given illustrating the improvements achieved from manual and automatic control after the installation of a coating mass gauge.