The grinding and brushing treatment of the substrate is to remove the dirt through the dual functions of the dissolution of alkali washing solution and the mechanical friction of the brush. The grinding and brushing treatment of color coating production line is designed to be mechanical, and the grinding equipment is also called brushing machine, which is usually composed of rotating brush roller, brush roller storage box, brush roller electric control device and alkali spray pipe circulation system
The grinding and brushing process is generally set between the primary and secondary degreasing sections. The special brush roller material is used to grind and brush the upper and lower surfaces of the substrate with the same or opposite rotation direction as the running direction of the steel strip. Through the friction generated by the high-speed movement of the brush and the substrate surface, the dirt and rough oxides on the substrate surface are removed, and the substrate surface is smooth
The mask is active.
There are usually two types of brush roller, compression type brush and bristle type brush. Compression type brush is a kind of brush that uses silicon carbide or alumina abrasives with very fine particle size to adhere to nylon wire, and then the nylon wire is made into fiberboard or cushion. After curing, the nylon wire is cut into a section of circular cylinder sleeve and installed on a roller core to make brush roller. The bristle brush is made of nylon wire containing silicon carbide abrasive. Abrasive particle size is different, the purpose is also different, two kinds of brushes have their own advantages and disadvantages. Because the abrasive grain size of compression type brush is very fine, and the pressure of brush roller on the surface of the plate to be brushed is relatively low, the surface of the substrate to be brushed is uniform. Its disadvantage is that the nylon wire is thin, easy to tear, and short service life. The outstanding advantage of bristle brush is that nylon wire has good wear resistance, so it has a long service life, which is about several times as long as compression brush. However, this brush is not suitable for treating thin plate substrate, which not only causes poor treatment effect, but also causes substrate curl. In order to prevent nylon filament from overheating and melting in the process of using brush roller type brush washer, alkali liquid should be continuously sprayed on the plate surface for cooling and wetting.
Note: the oil removal rate of aluminum Formula 1 is fast, but it has slight corrosion effect on the surface of the substrate. Aluminum formula 2 has good emulsifying and wetting properties, which is helpful to (2)
Eliminate the marks of the aluminum surface skin.
It can be seen from the formula table that the content of sodium hydroxide is the highest among several elements in the synthetic alkaline lotion. That is to say, (5) the concentration of alkali washing solution is high, that is, the content of sodium hydroxide is high. In principle, the decontamination ability of alkaline washing solution is related to its concentration. Increasing the usual concentration can accelerate the saponification reaction and improve the degreasing speed. But some substrates should not blindly increase the concentration, pour in the use of spray
For example, when cleaning galvanized sheet or zinc alloy sheet, if the concentration is too high, the substrate surface will be corroded by sodium hydroxide, which will affect the quality of the substrate
Washing effect. Therefore, for this kind of substrate, the degree of alkaline washing solution should be appropriately reduced. For cold rolled sheet, the concentration can be increased in the range of 1% ~ 2%.
In addition, in the usual alkaline detergent, the manufacturer will add a small amount of surfactant. When 0.1% ~ 0.2% (mass fraction) of surfactant is added into the cleaning agent, the surface tension of the solution can be greatly reduced, and the cleaning effect of alkaline cleaning solution can be fully exerted. However, the functions of various surfactants are different. For example, the degreasing rate of 4% (mass fraction) sodium metasilicate solution was 115%, while the degreasing rate of 3% (mass fraction) sodium metasilicate 2-18 solution was increased to 35%, 48% and 99.6% by adding 1% (mass fraction) Sodium Alkylbenzene Sulfonate, fatty alcohol sulfate and alkylphenol polyoxyethylene ether, respectively. In the actual production process, in order to ensure the cleaning effect of the substrate, the free alkalinity or total alkalinity should be measured regularly. The sampling frequency depends on the speed of the production line. The higher the speed of the production line, the more sampling times per shift,