To: Air spray gun construction is widely used in the coating industry, the efficiency is 5 to 10 times higher than the brush coating, the coating film is fine, smooth and beautiful. The general topcoats use air spray guns to achieve decorative purposes. What is the principle of an air spray gun? What are the characteristics of the air spray gun? What is the difference between air spray and airless spray? [Air Spray Gun] Air Spray Gun Principle Features The difference between air spray and airless spray Air spray gun principle and characteristics Principle of atomization: air spraying generally uses 0.3Mpa-0.6Mpa compressed air working pressure, and high flow rate flows through the air nozzle of the spray gun to form a partial vacuum around the nozzle. The paint is sucked into the vacuum space by compressed air, and the paint is atomized into small. The droplets are applied to the surface of the coated part to form a continuous coating film. Main features: It is simple in structure, easy to operate, easy to change color, and can adjust the size of the fan-shaped surface with the geometry of the workpiece to be coated, and the atomization effect is good. However, the air spray paint mist is easy to rebound and scatter, polluting the operating environment, and the paint utilization rate is only 25%-35%. The air sprayed paint is mixed with the compressed air, and the dust source and the oil-water filter device must be installed on the gas source to ensure the film quality. Introduction to spraying method First, air spraying (A), the principle of atomization Air spray generally uses a working pressure of 0.3Mpa-0.6Mpa compressed air, and a high flow rate flows through the air nozzle of the spray gun to form a partial vacuum around the nozzle. The paint is sucked into the vacuum space by the compressed air to atomize the paint into fine droplets. A continuous coating film is formed on the surface of the coated article. (2) Features and applications The main features of air spraying are simple structure, convenient operation and easy color change. The size of the jet fan surface can be adjusted according to the geometry of the workpiece to be coated, and the atomization effect is good. However, the air spray paint mist is easy to rebound and scatter, polluting the operating environment, and the paint utilization rate is only 15%-30%. The air-sprayed paint is mixed with compressed air. The dust source and oil-water filter device must be installed on the gas source to clean the compressed air to ensure the film quality. Air sprayed air source has a low working pressure, and it is difficult to atomize high-viscosity coatings. It is generally suitable for the spraying of decorative low-viscosity coatings. In today's coating industry, the most used air spray guns, especially for products with high film quality requirements, such as high-class cars, high-end furniture, etc., are air sprayed or air electrostatic spray. (3) Classification of air spraying 1. According to the feeding method 1 ), siphonic Siphonic spray guns are widely used air spray guns. The lower end of the spray gun is provided with a paint cup, and the compressed air flows at a high speed of the spray gun nozzle, and a partial vacuum is generated around the paint cup, and the paint inside the paint cup is sucked into the nozzle and atomized into a paint mist. The capacity of the paint cup is usually 600mL-1000mL. According to the amount of spray, the spray gun can be sprayed with compressed air. The spray nozzle should not be vertically up or down to prevent paint from leaking out of the vent hole of the paint cup. 2 ), gravity The gravity spray gun is used for small workpieces and touch up paint. It has a paint cup on the upper part and is transported down to the spray gun by the weight of the paint. According to the position of the paint cup relative to the axis of the spray gun, it is divided into the center and the side. In the spray application, the central type limits the tilt position of the spray gun; the side type can hold the paint cup in different positions at different positions. The paint cup of a gravity spray gun generally has a small capacity of 400-600 mL. The gravity spray gun is easy to change color and clean, and consumes less material. It is suitable for the color change process with frequent color change and the two-component paint with fast spray curing speed. 3 ), pressure type Pressure guns deliver paint to the gun by pressure. The spray gun itself does not come with a paint cup. The spray gun is lightweight and can be sprayed at any position and angle. Suitable for workpiece gap type, continuous spraying or coating line, the spraying efficiency is improved, and the film quality is good. Pressure spray paint conveyors are divided into two categories: pressure tanks and pneumatic double diaphragm pumps. The pressure barrel is a cylindrical pressure vessel, generally made of stainless steel or carbon steel. The pressure cover valve, pressure gauge and safety valve are installed on the lid to adjust the pressure of the input compressed air to reach the pressure of the output paint. Some pressure tanks are also equipped with pneumatic agitators. The capacity of common pressure tanks is 10L, 20L, 40L, 60L and so on. The pressure barrel has a simple structure, convenient maintenance, and a stable output pressure of the paint. The disadvantage is that the color change is inconvenient to clean. The pneumatic double diaphragm pump uses compressed air as the power, and the air pressure acts on the inner side of the diaphragm through the reversing mechanism, and the outer side of the diaphragm and the pump body together form a coating chamber whose volume can be changed. When the volume of the left coating chamber is changed from small to large, a partial vacuum is generated, and the next one-way valve is opened, and the one-way valve is closed, the paint in the paint bucket enters the left coating chamber under atmospheric pressure, and the volume of the right coating chamber is changed from large to small. The next check valve is closed, the paint creates pressure, and a check valve is opened to discharge the pump body. There are two coating chambers on both sides of the double diaphragm pump. When one volume is changed from small to large, the other volume is changed from large to small, and the round trip is repeated. Therefore, the double diaphragm pump has two times of material suction and discharge every time, which makes the output efficiency of the pump improve, and the output is relatively stable. Since the ratio of the input pressure of the compressed air to the output pressure of the paint is 1:1, adjusting the input pressure of the compressed air changes the output pressure of the paint. 2, by usage and flow *Repairing spray gun: flow rate 150-350mL/min * Standard production type spray gun: flow rate 150-600mL/min *High-load production spray gun: flow rate 250-1000mL/min *Special use air spray gun: (1) Airbrush: small size, suitable for advertising, painting and other occasions; (2) Special effect spray gun: It can produce random and strange figures such as spray guns, chaotic guns, etc., suitable for furniture, bicycles and other industries; (3) Two-component spray gun (common name double-mouth spray gun): The two coating components are mixed outside the muzzle and are suitable for two-component coatings such as unsaturated polyester; (4) Imitation stone paint spray gun: suitable for building decoration spray stone paint. *High flow low pressure spray gun (HVLP) The biggest disadvantage of traditional air spraying is that the utilization rate of the paint is low, the paint mist rebounds and scatters, and the equipment and environment are polluted. In the United States, according to the new strict air quality standards, the use of conventional air spray guns has been banned in some areas, replacing them with HVLP spray guns. The HVLP spray system consists of a large flow source, a feed system and a specially designed HVLP spray gun. The power of the HVLP spray gun atomizing paint is not the pressure of the compressed air but the flow rate, so the pressure of the material atomization is less than 0.07Mpa. In HVLP systems, pressure paint drums or double diaphragm pumps are generally used for pressure feed. 5M Measuring Tape,Automatic Tape Measure,Tape Measure Scale,Measuring Tape 5 Meter SHANGQIU CHAOYUE MEASURING TOOLS CO., LTD , https://www.calibrateds.com
Previous 1 23Next page
Show remaining content on this page