PURPOSE: To improve the rate of chemical conversion treatment without degrading the quality of a chemical conversion film by forming a fluid layer of a treating soln. in the upper part of a phosphate chemical conversion treating tank at the time of forming the phosphate film on the surfaces of steel plate products.
CONSTITUTION: In order to improve coatability of paint by forming a phosphate film on the surfaces of a product 12 made of a steel plate or the like, the product is immersed in the phosphating soln. in a chemical conversion treating tank 1, whereby a phosphate film is formed. The treating soln. accumulated in the accumulating chamber 3 formed by a partition plate 2 in this tank 1 is supplied to the nozzles 7 in the upper part of the tank 1 by a pump 9 and is ejected in a horizontal direction. The product 12 to be treated is formed with the chemical conversion film in a short time by the fluid layer 9 of the treating soln. by the ejecting flow, after which chemical conversion reaction is continued in the static treating soln. layer in the lower part, thence it is pulled up. Since the lower layer part of the treating soln. is in a static state, the sludge accumulating in the bottom is prevented from going up and sticking on the phosphating film.
MIYAWAKI KEN
FUJISAKI AKIO
MIYAJI MINEICHI
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