Galvannealing controlling and the latest developments in VAI-galvanizing technology

VAI has reached an improvement in its galvanizing technology by several developments. For the production of the best surface quality an improved concept of skin passing and tension levelling and an automatic galvannealling controller were developed. In order to economically produced galvanneal material of excellent quality, it is necessary to control the process conditions to fulfil all quality demands. For this reason VOEST-ALPHINE Industrieanlagenbau GmnH (VAI) and VOEST-ALPHINE Stahl Linz GmbH (VA Stahl) had jointly developed a new galvannealing process controller which allows for on-line calculation of the set point values for the relevant installations, such as heating power of galvannealing and soaking furnace and flow rate of air coolers. The controlling loop and some results of this new automatic control system are presented. The installation results in the reduction in off-tolerance strip length and, thus, realises a significant improvement of total yield.