The coating production line of the whole machine was designed by the former First Design and Research Institute of Machinery Industry. The design adopted the domestic advanced and mature craftsmanship at that time, and improved the mechanization and automation level of the coating production line to improve the working environment and reduce the labor intensity of workers; At the same time, we have conscientiously implemented relevant national laws, regulations, and standards, and strived to do a good job in environmental protection and occupational safety and health.
The entire production line is composed of 7 stations including on-line, drying, shielding, painting, leveling, drying, and off-line. In addition to the upper and the off-line, the 5 stations are composed of an integrated water trace drying room and shielding The room, the water spin spraying room, the leveling room and the drying room form a closed production line, which is separated from the car to ensure the relative cleanliness of the entire painting area. In addition, a complete machine cleaning section was built at one end of the workshop to perform secondary cleaning of the complete machine. The conveyor of the whole machine adopts double-plate ground chain transportation to improve the level of mechanization.
Process flow: water * degreasing cleaning-online-hot air drying-shielding-spray paint-leveling-drying-removing shielding-offline.
The operating time of each station is 45 minutes, and the tact time of the assembly line can be adjusted appropriately according to actual use.
The paint variety adopts Komatsu Yellow Acrylic Polyurethane Enamel, and the spray* adopts electrostatic mixed spray*.
The painting production line can reach an annual output of 2,000 loaders when only unit production is arranged. The total number of designers in the paint shop is 24, of which 16 are production workers. The average annual output of each production worker is 142 loaders.
2. Raising the problem
After entering 2003, due to the country’s increased investment in infrastructure, the loader industry has entered a booming situation in production and sales. Several major loader manufacturers have reached their respective highest output on record. At the same time, all manufacturers have improved the appearance quality. In terms of paint, the color of the loader is mainly carried out, that is, the appearance of the loader is divided into two parts, which has changed the single color of the loader for a long time.
With the increase in the output of loaders and the large-scale use of exterior paint coloring operations, several problems have appeared in the coating line of the whole machine during use:
(1) The coloring operation shortens the painting time on the outer surface of the loader (the area of one-time painting is reduced), and the shielding time has not been shortened, but has a trend of lengthening, which changes the beat of the entire assembly line. The impact is not significant, but some workstations have increased the waiting time, and part of the shielding work needs to be performed offline when the output increases.
(2) Due to the shortened tempo of the entire production line, and the water trace drying room has a heating process, so that when the temperature just rises to the specified temperature, it needs to be transferred to the next station, and it can’t be used at all. Function, and the water trace drying room is a through-type, the temperature drops to the ambient temperature immediately after opening the door.
(3) The drying room also has the same problem as the water-stain drying room, and it cannot fully play the role of drying.
(4) The door of each chamber adopts a pneumatic door, which takes a long time to open and close. It is about 3-5 minutes to fully open or fully close. If the whole beat is long (45min), it will appear to be a bit too long after the beat is shortened. NS.
(5) The utilization rate of the exhaust gas treatment device is too low. Because the exhaust gas in the painting room is fully mixed with water and the air volume is large, the content of organic solvents discharged into the atmosphere can meet the emission standards. The drying room uses hot air circulation, and a small part of the exhaust gas is discharged. This small part of the exhaust gas may exceed the standard. Therefore, most production lines have added an activated carbon adsorption device.
3. Suggestions for improvement
The above-mentioned problems cannot be completely solved by adopting the current batch-through production line. To completely solve the above-mentioned problems, the only way to fundamentally change the type of production line, or to adopt a through-type production line like an automobile production factory, for continuous operation, each chamber is relatively long, the entire production line does not have a door, and the drying room is equipped with a preset In the drying and forced cooling zone, the air curtain is used to intercept heat, or the chambers are arranged side by side. One spray room is equipped with 2-3 drying rooms. The loader enters the drying room immediately after painting, and it is leveled and dried during the heating process. Some large passenger car manufacturers use this method.
Four, actual operation
With the increasing output of loaders, the measures taken by our company are as follows:
(1) After the loader is cleaned and degreasing, take a natural drying method, and pay attention to maintaining a balanced production. If the weather is bad, use the evening time for drying.
(2) When the production line is working, the water trace drying room does not work, and most of the work of shielding is performed offline.
(3) The doors of all the chambers are not closed during painting to save time. As a result, it is easy to cause the paint mist to fly to the shielding room and the leveling room next to the spray booth.
(4) A new 720m2 parking shed is used to park the painted loaders, and repaint and decorate operations there; when the temperature is low, use the evening time for drying.
(5) Use tinplate to make some shielding glass baffles to save time for shielding glass.
Through the above measures, it is ensured that the paint shop of the company can produce 15-20 loaders per day without going to the night shift. Of course, the above measures are a bit harmful to the production line and are a last resort. In order to improve the drying problem in winter, the company plans to build a new drying room for the drying of the paint of the whole machine, and plans to move the water mark drying room offline to play its role.
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