ZINC OVER-COATING REDUCTION FOR IMPROVING SIGMA LEVEL OF GALVANIZATION PROCESS (original) (raw)
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International Journal of Engineering Research and Technology (IJERT), 2021
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Hot dip galvanizing of steel strip is carried out in Continuous Galvanizing Lines (CGL) in order to achieve consistency in thickness & quality of Zn-coating. The process is a complex one and is always in dynamic equilibrium depending on various process parameters. Around 20 process parameters, grouped into major sections like steel strip characteristics, pre-treatment, galvanizing process conditions, bath conditions, post treatment operations, are involved in the process. Zn-coating thickness is a nonlinear and coupled function of most of the above process input parameters. In the present work Artificial Neural Network (ANN) has been used to develop an off-line model to predict the coating thickness. Six factors that were identified through sensitivity analysis based on Taguchi's Orthogonal Array Technique were used as independent variables in the ANN model. A Hot Dip Process Simulator (HDPS) was used to generate the input-output data with close control of input process parameters. The data set generated for training purpose has the coating thickness variation between 12 to 32 µm. The model, developed with total data-sets (234), has the prediction error of 10%. However, the maximum data-sets (183) lie in the range of 20-30 µm and model developed by taking these datasets in this range has the prediction error of 7%. In both the cases a 6-(9-6-3)-1 network structure was used & 3/4 of data-sets were used for training & testing & 1/4 for validation.
Meliorating the Corrosion Tester for Galvanising Steel Production
In the hot-dip galvanising process, the molten zinc will corrode steel. The molten zinc corrosion tester has been developed to simulate the working condition in a zinc pot to find the best powder parameters for corrosion prevention. However, the original design of the tester may cause severe zinc oxidation and produces dross floating on the surface of the zinc pot. A large amount of unwanted dross must be removed to prevent interruption to the operation of specimens. In order to reduce the amount of dross, this study applied TRIZ methodology to develop an effective tester which minimised the formation of dross. The results demonstrate that the newly created tester is able to extend 160% of continuous operation time and reduce 61.5% of zinc waste. This method could be further applied in other rolls in hot strip mills and cold strip mills.