Electric field strength is the power of electrostatic coating, and its strength directly affects the effect of electrostatic coating (electrostatic effect, coating efficiency and coating uniformity, etc.). Within a certain range, the stronger the electric field intensity of electrostatic field, the better the effect of electrostatic atomization and attraction, and the higher the painting efficiency. Conversely, if the electric field intensity is small enough, corona discharge will be weak (or even not generated), the charge of coating particles will be small, and the efficiency of electrostatic atomization and coating will be poor. The strength of the electrostatic field depends mainly on the voltage and the distance between the car body and the electrode of the spray gun. It is proportional to voltage (U) and inversely proportional to polar distance (L). The calculation formula of average electric field intensity (E flat) is: E flat =U/L. According to experience, the most suitable electric field intensity for electrostatic coating is 3900 ~ 4000 V/cm. For reasons of safe operation and technology, the distance between the car body and the electrode of the spray gun is generally controlled within 25 ~ 30cm. At present, the recommended voltage for electrostatic spraying is: the built-in high voltage portable spray gun is 20,000 V, the external portable electrostatic spray gun is 50,000 ~ 60,000 V, and the robot rotary cup is 60,000 ~ 80,000 V. In the process of use, both automatic high-pressure spraying by robot and manual electrostatic spraying need regular detection of high-pressure parameters. If the fault needs to be repaired in time, high pressure has a particularly important effect on spraying quality and efficiency. 2. The original force of air pressure electrostatic spraying is electric field strength, and there is electrostatic atomization effect in the process of spraying. Therefore, under the same condition of pipeline paint delivery system, the pressure required by air electrostatic spraying gun is lower than that of ordinary air spraying gun. On the one hand, excessive air pressure will affect the normal operation of the turbine and generator; on the other hand, it will also affect the electrostatic effect. Excessive air pressure will produce a lot of paint mist rebound and weaken the electrostatic effect. Air pressure is usually 0.40 ~ 0.55MPa. In high speed rotary cup type electrostatic spraying robot, the size of the plastic air can only adjust the mist flow, and would be of paint, paint mist to not make produce on the edge of the cup by high speed mechanical spray paint drops again after atomization, so in the high speed rotating cup electrostatic spraying robot, it is recommended to use low plastic gas flow as far as possible, too much can cause serious coating rebound, influence of coating effect.
3 grounding requirements of electrostatic spray gun in the electrostatic spraying of the car body interior plate, because the body door brow, window frame and cylinder are small and slender shape, it is required to adjust to a smaller spray width to reduce paint spray, when spraying large areas of components such as the hood, car door plate can be appropriately increased spray width. Spray pattern overlap width should be maintained at a certain level, with a 66% overlap rate for medium coatings and a 75% overlap rate for silver, gold and other color coatings with high appearance requirements.
