Transient Characteristics Of Non-sensing Cylinders, Speed Characteristics Of Non-sensing Cylinders
Publish Time: Author: Site Editor Visit: 12
The solenoid valve is switched, and the gas source inflates the Rodless Cylinder rodless chamber through port A, and the pressure P1 rises. The gas in the rod chamber is exhausted through the exhaust port of the reversing valve through port B, and the pressure P2 drops. When the pressure difference between the rodless side and the rod side of the piston reaches above the minimum operating pressure of the non-sensing cylinder, the piston begins to move. Once the piston is started, the friction force at the piston and other places suddenly drops from static friction to dynamic friction, and the piston shakes slightly. After the piston is started, the rodless chamber is in an inflated state with an increased volume, and the rod chamber is in an exhaust state with a reduced volume. Depending on the external load size and the impedance size of the charging and exhaust circuit, the change rules of the pressures P1 and P2 on both sides of the piston are different, resulting in different changes in the movement speed of the piston and the effective output force of the non-sensing cylinder. The time from the solenoid valve being energized to the piston starting to move is the delay time. The time from the solenoid valve being energized to the piston reaching the end of the stroke is the arrival time.
During the entire movement process, the speed of the piston changes. The maximum value of the speed is called the maximum speed, recorded as um. For non-gas cushioned insensitive cylinders, the maximum speed is usually at the end of the stroke. For gas cushioned insensitive cylinders, the maximum speed is usually at the stroke position before entering the buffer.
The insensitive cylinder has no external load force, and it is assumed that the exhaust side of the insensitive cylinder is sonic exhaust, and the air source pressure is not too low. The insensitive cylinder speed obtained is called the theoretical reference speed.
u0=1920*S/A
Where u0 is the theoretical reference speed
S is the synthetic effective cross-sectional area of the exhaust circuit
A is the effective cross-sectional area of the exhaust side piston.
The theoretical speed is very close to the maximum speed of the insensitive cylinder when there is no load, so the maximum speed of the insensitive cylinder when there is no load is equal to u0. . As the load increases, the maximum speed um of the insensitive cylinder will decrease.
The average speed v of the insensitive cylinder is the movement stroke L of the insensitive cylinder divided by the action time (usually calculated by the arrival time) t of the insensitive cylinder. The speed of the insensitive cylinder usually refers to the average speed. In rough calculation, the maximum speed of the non-sensing cylinder is generally 1.4 times the average speed.
The operating speed range of the non-sensing cylinder is mostly 50~500mm/s. When the speed is less than 50mm/s, due to the increased influence of the friction resistance of the non-sensing cylinder and the compressibility of the gas, the piston cannot be guaranteed to move smoothly, and there will be a phenomenon of stopping and starting, which is called "creeping". When the speed is higher than 500mm/s, the friction heat of the non-sensing cylinder seal ring increases, accelerating the wear of the seal, causing air leakage, shortening the life, and increasing the impact force at the end of the stroke, affecting the mechanical life. In order to make the non-sensing cylinder work at a low speed, it is advisable to use a gas-liquid damping cylinder, or use a gas-liquid converter to use a gas-liquid combined cylinder for low-speed control. In order to work at a higher speed, it is necessary to lengthen the cylinder barrel, improve the processing accuracy of the non-sensing cylinder barrel, improve the material of the seal ring to reduce friction resistance, and improve the buffering performance.
