The Development Of Electrostatic Powder Spraying Controller

Electrostatic powder spraying process is widely used in instruments and home appliances coating in our country because of low pollution and high performance. In the process of powder coating, the factory can realize the reasonable supervisory control of spraying production line by means of electrostatic powder coating system, which reduces the production cost. At present, the controller of most domestic electrostatic powder spraying system adopts manual adjustment of air pressure, it needs employees to operate in the field operation with the dust which is harmful to employee’s health. Because manual adjustment of air pressure cannot guarantee powder device output precision and stability amount of powder, it affects the quality of spraying.This topic is aimed at the deficiency in most domestic electrostatic powder coating controller. This paper proposes an electrostatic powder spraying controller with the functions which can realize automatic adjustment of air pressure, constant voltage and constant current static control mode. The controller is composed of the controller panel and control part. The function of the controller panel is mainly to display the working parameters of the controller in real time and to communicate with external devices as communication interface; at the same time, it also has the extended function of setting parameters. The control part, as the core part of the controller, is responsible for exchanging data onto the display part and realizing real-time control of parameters in spraying process on the spot. The main contributions of this paper are summarized as follows:(1) This paper analyses the functional requirements of the control board in control part and confirms the parameters standard of the control board.(2) The maximum required moment to rotate the screw of relief valve can be estimated according to the working principle of the pressure reducing valve. According to the parameter of the moment, appropriate stepper motor is chosen. Thus, this paper accomplishes the selection of automatic pressure regulating device.(3) Function module circuits such as stepper motor drive circuit, air pressure acquisition circuit, the trigger signal processing circuit, RS422 communication interface circuits, are designed according to function requirements of the control board, the parameters standard of the control board and the parameters of stepper motor.(4) According to the real-time demand and peripheral resources demand of the circuit board, STM32F205 of ST firm is chosen as the micro-controller of control board, and the design of remaining circuits is accomplished.(5) The related function module drivers of control board are developed to improve the function of the control board.(6) This paper verifies the feasibility of the control board and automatic pressure regulating device by the experimental.