What is the principle of vacuum coating machine？

1. Vacuum main body——The size of the vacuum chamber varies according to the requirements of the processed products. At present, the widely used diameters are 1, 3M, 0, 9M, 1, 5M, 1, 8M, etc. The cavity is composed of "Stainless steel" target=_blank>Stainless steel material, requirements are not rusty, solid, etc., each part of the vacuum chamber has a connection valve to connect each pump.

2. Auxiliary air extraction system: The exhaust system is an important part of the vacuum system of the coating machine, which is mainly composed of mechanical pumps, booster pumps (mainly introduces Roots pumps), and oil diffusion pumps. This exhaust system is composed of "diffusion pump + mechanical pump + roots pump + cryogenic cold trap + polycold". The exhaust process is: the mechanical pump pumps the vacuum chamber to a low vacuum state of less than 2, 0*10-2PA, which provides a prerequisite for the subsequent vacuuming of the diffusion pump, and then when the diffusion pump pumps the vacuum chamber, the mechanical pump cooperates The oil diffusion pumps are connected in series to complete the pumping action in this way.
Mechanical pump: also called backing pump. Mechanical pump is the widely used low vacuum pump. It uses oil to maintain the sealing effect and relies on mechanical methods to continuously change the volume of the suction cavity in the pump to make the container pumped. The volume of the gas inside is continuously expanded to obtain a vacuum.

Classification of mechanical pumps: There are many types of mechanical pumps. Commonly used are sliding valve type (this is mainly used in large equipment), piston reciprocating type, fixed vane type and rotary vane type (this is currently the widely used, this article mainly introduces) four types Type. The mechanical pump starts to work from the atmosphere. Its main parameters are the ultimate vacuum and the pumping rate. This is an important basis for the design and selection of the mechanical pump. The single-stage pump can pump the container from the atmosphere to the ultimate vacuum of 1, 0*10-1PA, and the two-stage mechanical pump can pump the container from the atmosphere to 6, 7*10-2Pa, or even higher. The pumping rate refers to the volume of gas that can be discharged per unit time when the rotary vane pump is running at the rated speed. It can be calculated by the following formula: Sth=2nVs=2nfsL fs represents the cross-sectional area of ​​the cavity at the end of the suction, and L represents the void Cavity length, the coefficient indicates that the rotor has two exhaust processes per revolution, and Vs indicates that when the rotor is in a horizontal position, the suction ends, the volume in the cavity is the largest at this time, and the speed is n. The exhaust effect of the mechanical pump is also related to the speed of the motor and the tightness of the belt. When the belt of the motor is relatively loose and the speed of the motor is very slow, the exhaust effect of the mechanical pump will also become worse, so frequent maintenance is required. The sealing effect of mechanical pump oil also needs to be checked frequently. If there is too little oil, the sealing effect will not be achieved. The pump will leak air, too much oil will block the suction hole, and it is impossible to inhale and exhaust. The oil level is 0 or 5 cm below the line. Mechanical pumps are often used to pump out dry air, but cannot pump out gases with high oxygen content, explosive and corrosive gases. Mechanical pumps are generally used to pump out permanent gases, but they are not good for moisture. Effect, so it cannot remove moisture. The main parts of the rotary vane pump are the stator, rotor, shrapnel, etc. The rotor is inside the stator but has a different axis from the stator, like two inscribed circles. There are two shrapnels in the rotor slot, and a spring is installed between the two shrapnels. Ensure that the shrapnel is tightly attached to the inner wall of the stator.