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The surface degreasing of galvanized square tubes is a cleaning method based on the chemical effect of alkali. Because of its simple use, low price and easy availability of materials, it is widely used. Because the alkali washing process relies on saponification, emulsification and other effects, the above performance cannot be achieved with a single alkali.
Usually, a variety of components are used, and sometimes surfactants and other auxiliary agents need to be added. The alkalinity determines the degree of saponification reaction, and the high alkalinity reduces the surface tension between oil stain and solution, making oil stain easy to emulsify. In addition, the residual cleaning agent on the surface of galvanized square tube can be removed by water washing after alkali washing.
It is a widely used oil removal method to use surfactant with low surface tension, good permeability and wettability, and strong emulsification ability. Through the emulsification effect of surfactant, an interface facial mask with certain strength is formed on the oil-water interface, which changes the interface state and the price of Wuxi galvanized square tube, so that the oil particles are dispersed in the aqueous solution to form an emulsion. Or the oil stain insoluble in water on the galvanized square tube can be dissolved in the surfactant micelle through the dissolution effect of the surfactant, so as to transfer the oil stain to the aqueous solution.
Galvanized square tube is a kind of light thin-walled steel tube with hollow square section, which is also called steel cold-formed section. It is a type of section steel with square section size, which is made of Q235 hot-rolled or cold-rolled strip steel or coiled plate as the base material after cold bending and forming and then high-frequency welding. In addition to wall thickening, the corner dimension and edge straightness of the hot-rolled extra thick wall square tube reach or even exceed the level of the resistance welded cold formed square tube.
The advantages of real bending are small rebound, accurate forming, and accurate roll shape only. The R of internal angle forming is more accurate. The advantage of empty bending is that the side length can be bent when the actual bending cannot be carried out, such as synchronous bending and finishing of the upper/side edges of galvanized square tubes. The hollow bending can also bend the internal angle with R<0.2t without breaking the pipe wall.
The defect of real bending is tensile/thinning effect.
The actual bending will make the bending place stretch, and the stretching effect will shorten the longitudinal length of the bending line; The metal at the solid bend will become thinner due to stretching.
The defect of empty bending is that when the upper side/side side are simultaneously empty bending, because the upper roll and the lower roll generate pressure together, the galvanized square tube is in stock, and the forming force is easy to exceed the critical point, forming unstable concave edges, large diameter galvanized square tube, and will also affect the stable operation of the unit and the forming quality. This is also a different feature of the hollow bending of galvanized square tubes.