Take to the silicon steel in the continuous furnace for decarburization annealing, need to strip steel in the upper and lower surface of the uniform coating of magnesium oxide coating liquid. Magnesium oxide mainly plays the role of isolating agent to prevent the strip from sticking in the high temperature annealing stage, and at the same time can remove impurities such as nitrogen and sulfur in the steel, in addition to the reaction with the silicon dioxide on the surface of silicon steel, forming an excellent magnesium silicate insulation base layer. Therefore, magnesium oxide coating solution in the surface of oriented silicon steel coating quality plays a vital role in the quality of silicon steel products.
At present, the magnesium oxide coating solution is coated by a two-roller coating machine. The two-roller coating machine includes upper coating roller, lower coating roller, tray, magnesium oxide coating solution circulation device, and nozzle to spray the magnesium oxide coating solution in the magnesium oxide coating solution circulation device to the upper surface of the strip; the lower coating roller is immersed in the tray, and the magnesium oxide coating solution sprayed by the nozzle to the upper surface of the strip overflows into the tray, and the lower coating roller uses the magnesium oxide coating solution in the tray to coat the lower surface of the strip.
However, due to the magnesium oxide coating solution in the coating cycle, the flow of magnesium oxide solution in the tray is not smooth, magnesium oxide reacts with water to form magnesium hydroxide precipitation, magnesium hydroxide and carbon dioxide in the air combined to produce easy to precipitate magnesium carbonate. Magnesium carbonate and magnesium hydroxide mobility is very poor, easy to produce agglomeration deposition phenomenon. Therefore, the tray coating liquid mobility is not high, with the passage of time, the coating liquid is prone to accumulation of scale, resulting in poor coating quality of the lower coating rollers, along the strip rolling to the plate surface batch appear width, narrow, the number of double lines, and wear the lower coating rollers, directly resulting in product quality defects. In serious cases, it is also necessary to stop the machine to replace the coating rolls, clear the blockage of the circulation pipe, and deal with pallet scaling.
These unfavorable factors on the one hand greatly increased the labor intensity of workers, on the other hand, interfered with the site continuous production, directly affecting production efficiency, at the same time, due to the cured magnesium oxide coating liquid bonded in the tray can not be used, not only cleaning difficulties, but also caused magnesium oxide waste. In addition, due to the coating roller edge dumping liquid, affecting the coating quality, while interfering with the work of the coating machine, causing the coating roller edge scale accumulation, so that the strip edge coating is not uniform.