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Plunger valve maintenance and troubleshooting methods
Variety of plunger valve maintenance and troubleshooting (on) Content Note: The maximum output pressure of the valve is 40MPa, and has low noise, long life, axial radial suction load, low power consumption, integrated block design control quickly, from start to finish ... Because the hydraulic system used in the molding machine has more cylinders and the load of each station is different, it is very meaningful to apply the variable valve in the system. The valve output pressure of 40MPa, and has low noise, long life, axial radial load, low power consumption, manifold design and control of rapid, from start to finish with the valve locator and so on. First, the working principle of the plunger valve With a sliding shoe structure of the axial piston valve is currently the most widely used axial piston valve, placed in the cylinder block through the sliding shoe and swash plate contact, when the drive shaft When the cylinder rotates, the swash plate pulls or pushes the plunger out of the cylinder to complete the process of suction and discharge. Piston and cylinder bore the oil in the working chamber through the oil pan, respectively, with the valve suction and discharge chamber connected. The variable mechanism is used to change the inclination of the swashplate. The displacement of the valve can be changed by adjusting the inclination of the swashplate. Second, the maintenance of the plunger valve Swash plate axial piston valve generally adopts the cylinder rotation, face with the flow of the form. The cylinder end is inlaid with a friction pair composed of bimetal plate and steel with oil pan, and most of them adopt the method of plane distribution, so maintenance is more convenient. With the oil pan is one of the key components of the axial piston valve, the valve work, on the one hand the working chamber of the high-pressure oil to push the cylinder with the oil pan, on the other hand with oil pan and oil pressure between the formation of the cylinder Cylinder hydraulic reverse thrust cylinder away from the oil pan. The design pressure of the cylinder to the oil pan Fn is slightly larger than the hydraulic thrust Ff of the oil pan with the cylinder, that is, Fn / Ff = 1.05 ~ 1.1, which makes the valve work normally and maintains a high volumetric efficiency. In fact, there is often slight wear between the oil pan and the cylinder due to oil contamination. Especially under high pressure, even slight wear can make the hydraulic thrust Ff increase, thus undermining Fn III. Common Troubleshooting 1. Plunger valve output flow is insufficient or not output fluid (1) Insufficient suction. The reason is that the resistance of the oil suction pipe is too large or the amount of oil is insufficient. Such as the valve speed is too large, the tank surface is too low, into the tube leakage, filter plugging. (2) the amount of leakage is too large. The reason is the valve clearance is too large, caused by poor sealing. Such as oil pan with metal fragments, scrap iron and other scratches, face oil spills; variable agencies in the one-way valve sealing surface with poor, valve body and the oil pan bearing surface with trachoma or scratch marks. You can check the body of hydraulic fluid in the valve to determine the foreign body was damaged parts. Variable Plunger Valve Maintenance and Troubleshooting (Medium) (3) Inclined plate angle is too small, the valve displacement less, which need to adjust the variable piston to increase the inclination of the swash plate. 2. When the plunger valve displacement is not zero variable axial piston valve when the swashplate tilt is zero when the median, then the valve output flow should be zero. However, there is a tendency that the center deviates from the midpoint of the adjustment mechanism and there is still flow output at the midpoint. The reason for this is that the controller is out of position, loose or damaged, requiring zeroing, fastening or replacement. The valve's point of view is not enough to maintain the force, the angle of the trunnion wear and tear can produce this phenomenon. 3. Plunger valve output flow fluctuations Output flow fluctuations and many factors. The variable valve can be regarded as a variable control mechanism caused by poor, such as foreign bodies into the variable body, the control piston in the draw marks, wear marks, scars, etc., resulting in control piston instability. Due to insufficient energy in the amplifier or damaged parts, the damping effect of the spring-containing control piston is poor, resulting in unstable control piston motion. Flow instability is often accompanied by pressure fluctuations. Such failures generally open the hydraulic valve, replace damaged parts, increase damping, improve the spring stiffness and control pressure. 4. The output pressure of the plunger valve is abnormal The output pressure of the valve is determined by the load and is approximately proportional to the input torque. There are two types of output pressure abnormalities. (1) the plunger valve output pressure is too low When the valve in the self-priming state, if the inlet pipe leakage or hydraulic cylinder in the system, one-way valve, valve and so have a larger leak, will make the pressure rise Go up. This requires finding leaks, tightening, and changing seals to increase pressure. Pressure relief valve or adjust the pressure is low, the system pressure also does not increase, the pressure should be re-adjusted or overhaul relief valve. If there is a large amount of leakage due to the deviation between the hydraulic valve cylinder and the valve plate, in severe cases, the cylinder may rupture, and then grind the mating surface or replace the hydraulic valve. (2) the plunger valve output pressure is too high If the loop load continues to rise, the valve pressure continues to rise, when it is normal. If the load is fixed, the pressure of the valve exceeds the pressure required by the load. Check the hydraulic components other than the valve, such as the directional valve, pressure valve, transmission and oil return pipe. If the maximum pressure is too high, should adjust the relief valve. Variable plunger valve maintenance and troubleshooting (below) 5. Plunger valve vibration and noise Vibration and noise are simultaneously. They not only endanger the machine operator but also pollute the environment. (1) Plunger Valve Mechanical vibration and noise If the valve shaft and the motor shaft are not concentric or dead, shaft bearing, coupling damage, pad damage and loose fitting bolts will generate noise. For high-speed operation or transmission of large energy valve, regularly check and record the amplitude of each component, frequency and noise. If the valve's rotational frequency is the same as the natural frequency of the pressure valve, it will cause resonance and change the valve's speed to eliminate the resonance. (2) the noise generated by the liquid flow in the plunger valve pipe into the oil pipe is too small, the oil filter into the flow capacity is too small or blocked, the intake pipe into the air, the oil is too high, the oil is too low oil shortage And high-pressure pipeline produced liquid hammer, etc., will produce noise. Therefore, the correct design of the fuel tank, the correct choice of oil filters, tubing and directional valve. 6. Plunger valve overheating Plunger valve overheating for two reasons, one is mechanical friction heat. Due to the dry or semi-dry friction surface, the moving parts friction and heat. Second, liquid friction heat. High-pressure oil leaks into the low pressure chamber through various gaps, and a great deal of hydraulic pressure can be lost to heat energy. Therefore, the correct choice of moving parts between the gap, the tank volume and cooler, can prevent the valve overheating and oil temperature is too high. In addition, back to the oil filter blockage caused by back pressure too high, will cause the oil temperature is too high and the valve body overheating. 7. Plunger valve leakage The main reasons for the oil spill valve leakage: (1) shaft seal is damaged or shaft defects, scratches; (2) internal leakage is too large, resulting in increased pressure at the seal, and seal damage Or out; (3) The drain pipe too thin, so that the seal oil spills; (4) Valve external tubing loose, pipe joints damage, gasket aging or crack; (5) variable adjustment mechanism bolts loose, ; (6) cast iron valve casing with trachoma or poor welding. Now a lot of manufacturers producing plunger valves, imported parts and domestic pieces of different structures, each valve should be strictly in accordance with the instructions of its use of the factory. In the maintenance of the valve, the first valve should be checked in the system installation, the use of proper, easy to find out the causes of damage in time to eliminate hidden dangers and ensure the normal work of the system. Repaired hydraulic valve should pass certain testing equipment testing before use. If you do not have the test conditions, should also be repeatedly debugged in the system so that it can work normally. "Reprint marked source"