The principle and characteristics of the spraying method of the inner surface of the car body
At present, the interior surface spraying of automobiles mainly includes three methods: artificial air spray gun spraying, artificial electrostatic (air) spray gun spraying, and robot rotary cup spraying. When the traditional air spray gun sprays the inner surface of the car body, the paint transfer efficiency is only 25%~35%. The large amount of atomized paint is only a small amount attached to the surface of the car body, and most of the rest becomes overspray mist and is pressed into the paint by the air exhaust system. Paint slag in the mist capture system causes a lot of waste and VOC emissions. Moreover, a lot of chemicals (such as flocculants and flocculants) are required to treat these paint mists. The formed paint slag needs to be processed at a cost. The environment also has a big impact.
The paint on the outer surface of the car body basically uses the robot electrostatic spraying process, and the space for improving the material utilization rate is extremely small. Due to investment and construction history and other reasons, the interior surface spraying of automobiles is currently mostly an artificial air spraying process, which has a lot of room for improvement. There are two main ways to improve the paint utilization rate of the inner surface spraying; one is to completely transform into robot (rotating cup) spraying, but it needs to stop production and transformation and a large investment; the other is to change to manual electrostatic spraying, which has low investment. The effect is quick. The paint transfer efficiency of the two methods can reach up to 50%~70%.
The principle of electrostatic spraying is that the grounded object is the positive electrode, and the paint atomization device is the negative electrode. The atomized paint particles are charged through the electrification device, and an electric field is formed between the two poles, so that the paint can be effectively adsorbed On the surface of the object being coated. In an electrostatic spraying system, the current is like the liquid flowing in the fluid system, the power source is like a pump, the voltage is like the pressure, and the current is like the flow.
Although manual electrostatic spraying and robotic rotary cup spraying are the same in principle, they still have their own characteristics. Rotary cup spraying uses a high-speed rotating cup head to disperse the paint into small particles to achieve atomization. Artificial electrostatic spraying is the same as air spraying. The paint is blown away by compressed air to achieve atomization. The two methods have their own advantages in inner surface spraying: robot spraying has the characteristics of high automation and high efficiency; manual electrostatic spraying has the advantages of low investment and low maintenance costs.