Vacuum coating machine control system pressure control device

Vacuum coating machine control system pressure control device

(1) Control system composition

Vacuum coating machine in a vacuum device, due to the need of vacuum technology, and hope to maintain the pressure in the vacuum chamber to the impact of a given value, however, due to changes in the vacuum chamber to put gas or vacuum pump rate changes and other disturbing factors in, resulting in the vacuum chamber pressure deviates from the given value, and thus the need for automatic pressure adjustment. For small vacuum pressure automatically adjusts the pressure control device is usually chosen to be realized. Pressure control device for automatic pressure control system block diagram.

(2) the pressure control device selection
Vacuum coating machine pressure controller is selected based on technical requirements for vacuum apparatus and process for pressure control, pressure control of the general technical requirements for pressure control, control accuracy, reaction time, controlling the number of gas path, and control mode. Therefore, the choice of the pressure control device must meet the following requirements:

① control to meet the control requirements;

② controllable gas large ones should be equal to or greater than the required number of pneumatic control;

③ reaction the reaction time is less than the required time;

④ vacuum measurement range is greater than the pressure required adjustment range;

⑤ control instrument of pressure adjustment range is greater than the pressure of the controlled object requires adjustment range, namely vacuum flow regulating valve tuning range is greater than the pressure to regulate the flow range required range.
Where Pmax, Pmin-- adjust the minimum and maximum pressure [Pa];
Qvmax, Qvmin- a fine adjustment valve by the maximum and minimum gas flow [Pa.m3 / ls];
Se a vacuum controlled object (chamber) effective ventilation rate [m3 / s].