After the surface of cold rolled sheet production, sometimes will rust problems, seriously affect the surface quality of product, restrict the use of the following rules: rust, rust easily mass produced defects in winter, summer is not produced; pitting defects in flat roll before half of the volume is not easy to generate, in the second volume is easy to produce; rust plate on both sides above the central reflectivity reflectance; pitting defect serious to board about 400mm width distribution center.
The analysis thinks, may be caused by a variety of reasons flat liquid water residue leads to the defect, therefore the improvement measures for the:
1wet leveling system, according to the study of smooth solution working temperature should be controlled at35-40, below this temperature can cause pitting generation.
2while expanding nozzle diameter, ensuring the cleaning effect. Compressed air system of compressed air spray beam replacement for ' air knife '. Air knife on the spray holes evenly distributed, reducing the blowing literacy area, ensure the consistency of the spray angle.
3increase in compressed air heating device. Accelerate the layout of residual moisture, temperature, water vapor pressure is higher, the water more easily into the gas phase. Compressed air temperature is set to 80plus or minus 10 degrees, in a pipeline outlet temperature maintained at 40degrees, so that the rack at room temperature, rusty spot defect reduction.
4high voltage electrostatic oiler beam heating device improvement. Leveling unit electrostatic oiler, oiling effect is not good, so that oil can not form oil film, to increase the electrostatic oiler beam heating device, achieve better antirust function. This reduces pitting defects condition, at the same time stop later placed air corrosion occurs.
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