Introduction to the use of pneumatic actuators
Pneumatic actuator, also known as pneumatic device or pneumatic actuator, commonly known as pneumatic head, is a pneumatic actuator driven or regulated by air pressure. This paper describes the various technical requirements of the pneumatic head. structure
1. Pneumatic device is mainly made of cylinders. Piston. Gear shaft. End cap. Seals. Screw sleeve pneumatic devices shall also include an opening indication. Travel limit. Solenoid valve. Positioners. Pneumatic elements. Manual mechanism. Composed of signal feedback and other components.
2 pneumatic device and valve connection size should meet the requirements of ISO5211(bottom).GB/T12222 and GB/T12223 provisions.
3. When the air source is interrupted, the pneumatic device with manual mechanism should be able to open and close the valve with its manual mechanism. When facing the handwheel, the HANDwheel or handle should be turned counterclockwise to open the valve and clockwise to close the valve.
4. The end of the piston rod is internal. For the external thread, the spanner should be suitable for the standard spanner.
5. Piston ring should be easy to replace and maintain.
6. Pneumatic device with buffer mechanism, buffer mechanism travel length can refer to the provisions of Table 1.
7. Pneumatic device with adjustable buffer mechanism should have a mechanism to adjust the buffer effect outside the cylinder.
8. Cylinder inlet and outlet thread size should meet the requirements MANURNORM(attachment standard)GB/T7306.
1, GB/T7306.
2 and GB/T7307.
Performance 1GB/T12222 and GB/T12223 specifications
2. When there is no load, input the air pressure in the cylinder according to the provisions in Table 2, the operation is stable, no blockage and crawling.
3. At 0.6mpa under air pressure, pneumatic device starts. The output torque or thrust value of the two closed directions should not be less than the value marked by the pneumatic device, and the action should be flexible, without deformation and other abnormal phenomena.
4. When the high working pressure is used in the sealing test, the air leakage on the side of the respective back pressure shall not exceed (3)+0.15D)cm3/min(standard condition). The air leakage from the output shaft shall not exceed (3)+0.15d)cm3/min.
5, strength test with 1.5 times the large working pressure test, keep the test pressure for 3 minutes, the cylinder end cover and static sealing parts are not allowed to have leakage and structural deformation.
6. Action life time, pneumatic device to simulate valve action. The opening and closing operation shall be performed not less than 50,000 times (one opening and closing cycle) while maintaining the output torque or thrust capability in both directions.
7. When the piston moves to the end of the stroke, the pneumatic device with buffer mechanism does not allow impact.
Surface and appearance quality
1. End cover of casting cylinder. End flange. No scratches on the box. Cut marks, air holes, burrs, etc.
2. The outer surface coating or chemical treatment layer of the pneumatic device should be smooth. Smooth. Uniform color, no grease. Indentation and other mechanical damage. Test methods for pneumatic heads
Test Methods No load test
1. Horizontally placed pneumatic device, according to the prescribed pressure alternately applied to both sides of the cylinder, exhaust side to the atmosphere, so that the pneumatic device switch operation. The test results should conform to the regulations.
2. During the no-load test, the cylinder with buffer mechanism should be thoroughly opened. The strength test takes 70% kerosene and 30% ingot oil mixture or compressed air as the medium.5 times the working pressure of the cylinder (the maximum allowable pressure), apply pressure to the cylinder alternately, keep the pressure for 3min, observe the cylinder disassembly and check, and the results should meet the provisions of (performance 5). Safety precautions must be taken when conducting air tests.
In load test, the pneumatic device is installed on the test bench, and 0.6mpa compressed air is applied to the cylinder, and the torque or thrust is gradually applied to the output shaft. The output torque or thrust of the pneumatic device is measured, and its value is not less than the specified value of the pneumatic device logo. At the same time, check the manual mechanism, opening indicator, travel limit, information feedback and other components one by one, and the results should conform to the provisions of (performance 3).
No load, pneumatic device from the two inlet alternately apply large working pressure 1. Compressed air 1 times, check the piston, output shaft leakage. When the pressure is maintained for 3min, the leakage shall meet the requirements of (performance 4). Another seal test method: check the pressure indicates the pressure, for 5 min, the gauge pressure does not drop to qualified. Take one of the two approaches.
Action life test The pneumatic device is installed on the test bench. Under the load of rated output torque, the opening and closing process of the drive valve is simulated until the output torque or thrust of the pneumatic device is less than the specified rated torque or thrust. The operation life should meet the regulations.
