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Treatment of Surface Problems of Galvanized Coil
Galvanized coils are widely used in construction, car, household appliance, and other manufacturing industries because of their ideal corrosion resistance, forming, welding and spraying, and other comprehensive advantages than low cost and good appearance. During the production of galvanized steel sheets, stripe highlights and forehead wrinkle defects will continue to appear, jeopardizing the quality of the material, and the use of customers must be controlled.
1. Strip highlighting
The appearance of the strip-shaped prominent defects is usually the same as that of the cold-rolled, staggered strips of canine teeth. It looks like a scratch defect. Differently, the number of strip-shaped highlighted defects is never fluid, so it greatly affects the force analogy fluidity. The cause of this defect is due to material defects.
(1) Improve the composition scheme of the ironmaking process, and adjust the manganese-sulfur ratio of the iron liquid in the demonstration point; in addition, formulate the seasonal flow system of the second cold water flow to distinguish the intrusion caused by seasonal factors throughout the year.
(2) In the steel rolling process, the upper part of the five teeth is never coated with a coated crystallizer in the lower half.
(3) Improve the processing technology and weapon equipment before the hot-dip galvanizing process to minimize the natural environment caused by the continuous emergence of weapon equipment. In addition, the cold rolling production will reduce the heavy cold rolling force of the first pass, thus replacing the natural environment caused by the roughness of the rolled material that has been cut roughly.
2. Forehead wrinkle defects
Some of it is like a wrinkle on the forehead, so it is called a forehead wrinkle. The hot-dip galvanized steel sheet contains horizontal pattern defects and the fluidity of the zinc solution, and the Coriolis air mass is generated during the process of the re-quenching system. The low cost PPGI prepainted galvanized steel coil sheet is easy to cause the galvanized steel sheet to continuously appear forehead wrinkle defects.
(1) Properly increase the temperature of the zinc liquid and the speed of the hot-rolled steel strip, or reduce the aluminum water content in the zinc liquid and increase the aspect ratio of the demister to increase the circulation of the Zn liquid in the demister area.
(2) Increasing the pressure of the bumpy roller, and raising the bumpy effect. Increase the number of flexed areas, reduce the total width of flexed areas, and relieve wrinkles on forehead.
(3) To reduce the tensile strength of tension and straightening, it is to replace the total plastic deformation.