Spray gun and electrostatic controller In addition to the traditional built-in electrode needle, the spray gun is also equipped with a ring corona outside to make the electrostatic field more uniform to keep the thickness of the powder coating uniform. The electrostatic controller generates the required electrostatic high voltage and maintains its stability, and the fluctuation range is less than 10 percent . Powder supply system The powder supply system consists of a new powder bucket, a rotary screen and a powder supply bucket. The powder coating is first added to the new powder bucket, and the compressed air pre-fluidizes the powder through the micro-holes on the fluidizing plate at the bottom of the new powder bucket, and then is transported to the rotary sieve through the powder pump. The rotating sieve separates the powder particles with excessive particle size (above 100μm), and the remaining powder falls into the powder supply bucket. The powder supply barrel will fluidize the powder to a specified level and then supply the spray gun to spray the workpiece through the powder pump and the powder feeding pipe.
Except for a part of the powder sprayed from the spray gun of the recovery system that is adsorbed on the surface of the workpiece (generally 50 percent to 70 percent , the company is 70 percent ), the rest of the powder settles naturally. Part of the powder in the sedimentation process is collected by the cyclone collector on the side wall of the powder spray booth, and the powder particles with larger particle size (above 12 μm) are separated by the principle of centrifugal separation and sent back to the rotary screen for reuse. The powder particles below 12pom are sent to the filter element collector, where the powder is vibrated by the pulsed compressed air and falls into the collection bucket at the bottom of the filter element. This part of the powder is regularly cleaned and boxed for sale. The clean air from the separated powder (containing powder particle size less than 1 μm and concentration less than 5g/m3) is discharged into the powder spraying chamber to maintain a slight negative pressure in the powder spraying chamber. If the negative pressure is too large, it is easy to inhale the dust and impurities in the powder spraying room. If the negative pressure is too small or the positive pressure is easy to cause the powder to overflow. The powder that settles at the bottom of the dusting booth is collected by the powder pump and enters the rotary screen for reuse. The mixing ratio of recovered powder and new powder is (1:3)-(1:1). Using this recycling system, the company's overall powder utilization has averaged 95 percent . The top plate and wall plate of the powder spraying chamber are made of light-transmitting polypropylene plastic to minimize the amount of powder adhesion and prevent the accumulation of electrostatic charges from interfering with the electrostatic field. The base plate and base are made of stainless steel, which is easy to clean and has sufficient mechanical strength. Auxiliary systems include air conditioners and dehumidifiers. The function of the air conditioner is to keep the powder spraying temperature below 35 degree to prevent powder agglomeration; the second is to maintain the micro-negative pressure of the powder spraying chamber through air circulation (wind speed less than 0.3m/s). The function of the dehumidifier is to keep the relative humidity of the powder spraying room at 45 percent to 55 percent . If the humidity is too high, the air is prone to discharge and break down the powder coating.
