Hydraulic press plunger pump repair
1. Fault analysis and troubleshooting
(1). The output flow is not enough or not oiled at all.
1. Inhalation resistance is large; if the oil level of the fuel tank is too low, the suction filter is clogged. The suction pipe is too long and the elbow is too much, resulting in a large loss of resistance along the oil suction passage and insufficient output flow.
2. The pipe joint exposed in the atmosphere is not tightened or the seal is not tight. The intake air is difficult to form the necessary vacuum in the pump. The atmospheric pressure cannot press the oil into the pump. The pump must check the oil temperature and corresponding before starting. Pump shut-off valve, while the pump needs to be filled with oil
3. The concentricity of the motor and oil pump coupling is not enough, or the coupling and elastomer are damaged.
4. The pump's centering spring is damaged, so that the plunger return is not enough or can not return, causing the seal between the cylinder and the oil distribution plate to lose performance.
5. There is dirt jamming on the joint surface of the oil distribution plate and the cylinder block, or the surface is pulled, and the grinding oil distribution plate and the cylinder joint surface are cleaned.
6. There is a groove between the plunger pump and the cylinder body that is worn or strained.
7. It is possible for a constant pressure variable pump, such as controlling the plunger of the swash plate to block, causing the swashplate to be too small or not inclined at all.
8. When disassembling and assembling, the oil distribution plate holes are not aligned with the positioning pins installed on the positive pump cover, so they can withstand each other, and the oil distribution plate and the cylinder body cannot be fitted together, resulting in short-circuiting of high and low pressure oil and liquid. oil
9. The oil temperature is too high and the pump has a large internal leakage.
10. The leakage caused by the failure of other components of the system is large
(2). The pressure is not high or not pressed at all.
1. The above reasons for “not enough output flow or no oil at all” will result in low pressure or no pressure at all.
2. The inclination of the variable is too small, so that the output is too small for the flow, and the inclination of the variable can be appropriately increased.
3. For the pressure compensated variable pump, the spring that may be the characteristic of the control variable is not adjusted, the pressure regulating mechanism is faulty, etc.
4. Failure of other components of the hydraulic system
5. The steering of the motor is not equal
(3). Pump noise and large pressure fluctuations
1. The pump oil pipe sucks in air, causing large noise fluctuations.
2. Servo piston and variable piston movement is not flexible, occasional or frequent pressure fluctuations
3. For the variable pump, it may be because the deflection angle of the variable mechanism is too small, the flow rate is too small, and the internal leakage is relatively increased, so the oil supply cannot be continuously supplied, the flow rate is pulsated, and the pressure pulsation is caused.
4. The plunger ball head and the sliding shoe cooperate loosely
(4). Pump heating fluid temperature rise is too high
1. Pump plunger and cylinder hole. Due to wear and strain between the oil pan and the cylinder joint surface, the internal leakage increases, and the heat is converted into heat.
2. The pump's internal motion pair is seriously worn and pulled.
3. The viscosity of the oil is too large, the tank volume is too small, the oil pump or system leaks too much, etc.
4. Pump bearing wear or pump and motor coupling are not concentric enough
(5). The oil pump leakage pipe leaks seriously
1. Cylinder block and oil distribution plate. Parts such as plunger and cylinder hole are seriously worn, resulting in increased internal leakage.
2. Variable piston or servo piston wear causes leakage
3. Pressure regulating mechanism failure
2. Piston pump assembly
1. Before assembly, all parts or components to be assembled should be inspected again to make a record.
2. Remove burrs from various parts, especially sharp corners
3. All parts should be carefully cleaned before assembly, beware of impurities, dust, dirt, etc. mixed into the surface of each fitting in the pump to avoid scratching the smooth surface of each fit;
4. When assembling, force or beat, it is hard to beat the parts with the hammer when hitting, and pass the intermediate (such as copper rods and wooden sticks);
5. When assembling, be careful to prevent the steel ball of the centering spring from falling off. First, apply the steel ball to clean the grease. When the steel ball sticks to the inner sleeve of the spring or the returning plate, assemble it again. Otherwise, if the steel ball falls off during assembly, the pump = Inside, during operation, other parts in the pump must be damaged, so that the pump cannot be repaired;
6. There is a positioning pin on the joint surface of the pump body and the oil distribution plate. Under normal circumstances, do not pull out. If the end surface of the oil distribution plate is pulled out, pay attention to the pin on the pump body when reassembling. The correct position, if you make a mistake, you can't suck oil.
3. Installation of axial piston pump
1. The four-column hydraulic press oil pump can be installed with bearings or flanges. The pump and motor should have a common foundation support. The flange and foundation should have sufficient rigidity to avoid vibration when the oil pump is running.
2. When the rotating shaft of the pump and the output shaft of the motor are installed, the concentricity must be ensured. The method of aligning is as follows: support installation: guarantee of the installation accuracy of the motor output shaft and the support and inspection method. The vibrating tolerance is 0.10mm. The original error of the semi-coupling magnetic dial gauge seat mounting end face to the verticality of the coupling is not more than 0.01mm; the eccentricity of the drive shaft and the pump shaft is less than 0.05TIR, and the pump shaft cannot be subjected to the vertical direction. Generally, it should be horizontally installed. ;
3. The oil pump must confirm the direction of rotation of the pump during installation, and the direction of rotation of the pump is the same when wiring.
4. Use of axial piston pump
1. Before installing the test drive, the fuel tank, piping, actuators and valves must be cleaned. The new oil poured into the fuel tank must be filtered by the oil filter to prevent system contamination caused by uncleanness such as oil drums;
2. It is strictly forbidden to open the fuel tank cap due to system heating during use, and other measures must be taken;
3. Start of the oil pump
A. Before the first start of installation, the oil pump must be filled with clean hydraulic oil through the drain port on the pump casing, otherwise it cannot be started;
B. Check if the coupling is concentric;
C. Check if the steering of the motor matches the specified direction of rotation of the oil pump;
D. Start and stop the start button several times before the pump starts, confirm that the oil flow direction is correct and the pump sound is normal before running continuously.
4. Load operation
A. Low load operation: after the above preparation is completed, the pump is operated for 10-20 minutes under the pressure of 10-20 bar;
B. Full-load operation: After low-load operation, gradually adjust the relief valve. Safety valve. The pressure of the hydraulic pump to the maximum pressure of the system for 10-15 minutes, check whether the system is normal. The temperature of the oil pump does not exceed 70-80 °C
C. After the above load operation is completed, the system can enter normal operation (for the reinstalled hydraulic system, the system pressure test is also required, generally 1.5 times the system working pressure);
D. The running time under the maximum use pressure shall not exceed 10% of one cycle time, generally within 6 seconds.
Hydraulic piston pump use and maintenance