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A suggestion of a new method for the calculation of the coating thickness in continuous hot-dip galvanizing

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Abstract

It is known that the distributions of the impinging pressure gradient and the shear stress at the strip surface play a decisive key role in the decision of the coating thickness in hot-dip galvanizing. So, to predict the exact coating thickness, it is essential that the distributions of the impinging wall jet pressure and the shear stress acting between the liquid film and jet stream are measured (or calculated) exactly for each specific coating condition. So far, to obtain the impinging wall jet pressure, it was assumed that the jet issuing from an air-knife is similar to the Hiemenz plane stagnation flow, and the wall shear stress could be predicted by an equation using the assumption of a non-negative Gaussian profile in impinging wall jet pressure in general, so that it cannot be reliable for some impinging wall jet regions and nozzle systems intrinsically. Nevertheless, one cannot find a suitable method to cope with the difficulties in measuring/calculating of the shear stress and the impinging wall jet pressure. Such a difficulty which will cause an inaccuracy in the coating thickness prediction. With these connections, in the present study, we suggest a new method named as a two-step calculation method to calculate the final coating thickness, which consists of the air jet analysis and coating thickness calculation. And, from the comparison of the results one may confirm the validation of the new suggested method.

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Authors and Affiliations

  1. School of Mechanical Engineering, Kyungpook National University, 1370, Sankyuk-dong, Daegu, 702-701, Korea

    C. M. Jo, Y. D. Kwon & S. B. Kwon

  2. POSCO Technical Research laboratories, 699, Gumgo-dong, Jeonnam, 545-090, Korea

    G. Y. Kim

Authors
  1. C. M. Jo
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  2. G. Y. Kim
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  3. Y. D. Kwon
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  4. S. B. Kwon
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Corresponding author

Correspondence to S. B. Kwon.

Additional information

This paper was recommended for publication in revised form by Associate Editor Simon Song

Soon-Bum Kwon received his B.S. and M.S. degrees in Mechanical Engineering from Kyungpook National University in 1974 and 1980, respectively, and his Ph.D degree from Kyushu University in 1987. He is a Professor at the school of Mechanical Engineering at Kyungpook National University, Korea. His research interests are compressible gas dynamics and nonequlibrium condensation.

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Jo, C.M., Kim, G.Y., Kwon, Y.D. et al. A suggestion of a new method for the calculation of the coating thickness in continuous hot-dip galvanizing. J Mech Sci Technol 25, 2781–2786 (2011). https://doi.org/10.1007/s12206-011-0907-9

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  • DOI: https://doi.org/10.1007/s12206-011-0907-9

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