The development of China's coating production line has gone through the development process from manual to production line to automatic production line. China's painting process can be simply summarized as: pre-treatment → spraying → drying or curing → three waste treatment. China's coating industry really originated after the introduction of Soviet technology in the 1950s. Some of the aided projects have begun to establish coating production lines, but these production lines are generally a combination of steel plate welded groove and steel structure spray (painting) paint room and drying room (furnace), and the workpiece is manually suspended by electric hoist (a few Operate with a hanging conveyor). At that time, the pickling tanks were generally lined with lead steel. With the development of the times, there were linings of glass reinforced plastic or all of the grooves made of glass reinforced plastic. Since the 1960s, due to the development of light industry, the production line of mechanized production and the assembly line of automated production have appeared in the bicycle manufacturing industry, as well as the program-controlled assembly line formed by the program-controlled trolleys based on the production of the original tank assembly line. In the Shanghai and Tianjin regions. During this period, the main task of China's coating industry was to focus on anti-corrosion. However, with the development of China's economy and the development of foreign coating technology, through the introduction of technology and exchanges with foreign technology, China's coating technology has begun to develop rapidly, in the field of automatic coating production, electrostatic spraying and electrophoretic painting technology. Promote the application and development of powder coating technology, especially in China's home appliance industry, daily hardware, steel furniture, aluminum components, electrical products, automotive industry and other fields, so that the coating industry has made significant progress, Intelligent painting robots have also appeared in the coating line.
Pretreatment process development
As a pretreatment technique, the conventional method of initial pretreatment is a tank immersion type, which is impregnated groove by tank according to the process flow. With the improvement and development of the process, two-in-one (ie degreasing, descaling) and three-in-one (ie degreasing, descaling, passivation) processes have emerged. At present, foreign and domestic appliance industries mostly adopt spray-type pre-treatment, which is characterized by high production efficiency, simple operation, easy to realize production automation or semi-automation, good degreasing effect, and dense and uniform phosphating film. However, no matter how it develops, the pretreatment process of surface treatment is necessary. For different coating requirements and anti-corrosion requirements, the treatment methods such as degreasing, descaling and phosphating should be selected according to the condition of the raw materials of the workpiece. Of course, in the pre-treatment process, sand blasting, shot blasting or sanding processes are also selected as needed in different sectors of different industries. In the development of the times, the surface treatment process is developing. In the case of water washing, tap water is generally used first. However, with the process requirements and development, distilled water or purified water has been used for water washing; the pretreatment also has an ultrasonic treatment process.
Spraying process development
Since the 1980s, China has begun to introduce some spraying equipment or single equipment. Some foreign paint spray mist treatment devices have also been developed through the introduction of digestion and absorption, such as rotary cup painting, water curtain painting, water spinning and other series of spraying and painting. The method of mist treatment has made the painting technology a step forward, especially the paint liquid treatment technology of electrophoretic painting in the 1980s. When the electrophoretic painting was first started in the mid-1960s, the paint solution was treated with a nylon shawl, and the temperature control was cooled with an ice pack. With the advancement of the times, from the 1980s to the 1990s, there were a series of devices such as ultrafiltration for the treatment of electrophoresis bath. The UF (Ultrafiltration)/RO (Reverse Osmosis) system used in recent years will be an indispensable equipment for the new cathodic electrophoresis coating line in the future; for the temperature control, not only the cooler, but also the chiller is specially set up for the production line. The cycle is cooled.