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1. Causes and elimination of vibration and noise
(1) Inhaling air
The pump body of 1CB-B gear pump is in direct contact with the two end caps. If the flatness of the contact surface does not meet the specified requirements, the pump will easily inhale air during operation; likewise, the end cap and pressure of the pump The cover is also in direct contact, and the air is also easy to invade; if the gland is a plastic product, it may be deformed due to damage or deformation due to temperature changes, and the air may enter the air. The way to eliminate this kind of failure is: when the flatness of the pump body or the pump cover does not meet the specified requirements, it can be ground back and forth on the flat plate with gold steel sand according to the "8" shape route, or it can be ground on the surface grinder. The flatness is not more than 5μm, and the verticality of the plane and the hole needs to be ensured; for the leakage of the pump cover and the gland, an adhesive such as epoxy resin can be used for sealing.
2 The pump shaft is generally sealed with a skeleton oil seal. If the spring of the clamping lip is detached, or the oil is packaged backwards, or the lip is pulled or aged, the rear end of the oil seal is often under negative pressure and the air is taken in. Generally, the new oil seal can be replaced.
3 The oil in the fuel tank is not enough, or the suction pipe port is not inserted below the oil surface, the pump will take in the air. At this time, the oil should be replenished to the oil mark line; if the oil return pipe is exposed to the oil surface, sometimes it will be The instantaneous negative pressure in the system causes the air to back into the system, so the return pipe should generally be inserted below the oil level.
4 The installation position of the pump is too high from the oil level, especially when the pump speed is reduced, because the pump suction chamber cannot guarantee the necessary vacuum to cause insufficient oil absorption to absorb air. At this time, the relative height of the pump and the oil surface should be adjusted to meet the specified requirements.
5 The oil suction filter is blocked by dirt or its capacity is too small, resulting in increased suction resistance and intake of air. In addition, the larger diameter of the inlet and outlet ports may also bring in air. At this time, the oil filter can be cleaned, or an oil filter with a larger capacity and an appropriate diameter of the inlet and outlet can be selected. In this way, it not only prevents the inhalation of air, but also prevents noise.
(2) Mechanical reasons
1 The connection between the pump and the coupling generates vibration and noise due to irregular requirements. The coupling should be adjusted as required.
2 Noise is generated due to dirt and oil entering the pump causing wear and tear on components such as gears. The oil should be replaced, the filter should be reinforced, and the pump should be disassembled; the gears with severe wear must be repaired or replaced.
3 Damage or wear of the pump parts will cause vibration and noise: if the tooth shape error or the weekly error is large, the two gears have poor contact, the tooth surface roughness is high, the length of the common normal line is too poor, the back side gap is too small, and the two meshing gears The contact area is not in the indexing circle position or the like. At this point, the gear can be replaced or the gear pair can be ground. At the same time, the bearing needle holder damage, the long shaft journal and the needle wear, etc., can cause the bearing to rotate poorly and produce mechanical noise. At this time, the gear pump needs to be dismantled and the needle bearing replaced.
4 The axial assembly clearance of the gear is too small; the sliding joint between the gear end face and the front and rear end caps cannot be carefully removed due to the burrs of the gear before assembly, so that the joint surface is pulled during operation, so that the internal leakage is large, resulting in a decrease in output flow; The dirt enters the pump and wedges into the gap between the gear end face and the front and rear end caps to pull the mating surface, causing the high and low pressure chambers to communicate due to the radial strained groove, so that the output flow is reduced. The above measures should be used to repair the above conditions. Disassemble the gear pump, appropriately increase the axial clearance, that is, the end face of the grinding gear; use a surface grinder to smooth the front and rear cover end faces and the gear end faces, and remove the burrs on the gear teeth (cannot be chamfered); The depth dimension of the unloading groove on the end face of the end cap may vary, and the width should be appropriately increased.
(3) Other reasons
High viscosity of the oil also produces noise, and it is necessary to use an oil of appropriate viscosity.
2, the output flow is insufficient
1 The high oil temperature will lower its viscosity and increase the internal leakage, which will reduce the pump output flow. Measures should be taken to determine the cause; for medium and high pressure gear pumps, the seal should be inspected for damage.
2 If the viscosity of the selected oil is too high or too low, the output flow of the pump will be reduced, and oil with acceptable viscosity should be used.
3CB-B gear pump can not be reversed. If the pump body is installed, it will cause the pressure oil chamber and the oil suction chamber to be short-circuited locally, so that the flow rate can be reduced or even oil can not be sucked. At this point, the steering of the pump should be checked.
4 The engine speed is not enough, causing the flow to decrease. The cause should be identified and excluded.
3, poor rotation
1 Axial clearance or radial clearance is too small. Re-adjust and adjust.
2 There is dirt in the pump. Disintegrate to remove foreign objects.
3 assembly is wrong. The machining reference surface of the two pin holes of the gear pump is not the assembly reference surface. If the pin is driven in first, and then the screw is tightened, the pump will not move. The correct way is to tighten the screw while turning the gear pump, and finally drill the pin hole and drive the pin.
4 The pump has poor coaxiality with the engine coupling. The coaxiality should be within 0.1mm.
5 The parts inside the pump are not demagnetized. All parts must be demagnetized before assembly.
6 The needle roller sleeve is unqualified or the needle is broken. Repair or replace.
7 The working oil outlet is blocked. Remove foreign objects.
4, fever
1 The causes of the poor rotation of the gear pump can cause the gear pump to heat up. The elimination method can also be implemented with reference to it.
2 oil viscosity is too high or too low. Re-select oil.
3 Side plates, bushings and gear end faces are severely rubbed. Repair or replace.
4 The ambient temperature is high, the volume of the fuel tank is small, and the heat dissipation is poor, which will cause the pump to heat up. Should be handled separately.
5, the repair of the main parts
(1) gear
1 Tooth shape repair: remove the strained or multi-angled parts with fine sand cloth or oil stone, then change the gear meshing surface and properly research it, and finally clean it; the severe wear can be observed with the naked eye. Parts should be replaced.
2 Face repair: the end face of the gear wears due to the relative rotation of the bearing seat or the front and rear covers. When it is light, it will take up the line. The burr marks can be ground and polished by grinding method. When the wear is serious, the gear should be placed on the surface grinder. Grinding. It should be noted that the two gears must be placed on a surface grinder for grinding. The purpose is to ensure that the difference between the thickness of the two gears is within 5 μm. At the same time, the perpendicularity of the end faces and the holes and the parallelism of the two end faces must be 5 μm. Within the scope, use the oil stone to make the sharp edge blunt, but do not chamfer, so that there is no burr, flashing edge.
3 When the meshing surface of the gear wears, the application of the oil stone removes the burr generated by the wear; at the same time, the gear meshing orientation is changed, so that the tooth surface which is not engaged with the meshing work is engaged, so that the original working performance can be ensured. It can also extend the working life of the gear.
(2) pump body
The wear of the pump body is mainly on the side where the inner cavity is in contact with the circle of the gear, and occurs mostly on the oil suction side. If the pump body is symmetrical, the pump body can be turned over 180 degrees before use; if the pump body is asymmetric, the plated bronze alloy process or brush plating method should be used to repair the wear parts of the pump body cavity.
(3) bearing race
The wear of the bearing race is generally on the end face that is in contact with the gear and the inner bore that is in contact with the needle roller. When the end face is worn or the wire is pulled up, the four bearing races can be placed on the surface grinder, and the roughened end faces are grounded on the basis of the side not in contact with the gears, and the precision should be within the range of 10 μm. The bearing races are generally less worn and can be ground if the wear is severe; or the hole diameter is appropriately increased and the needle roller is re-selected; or the bearing race is replaced.
(4) long and short axes
The failure of the long and short shafts is mainly caused by the contact with the needle bearing. If the wear is slight, a buff finish (and a new needle bearing) can be used; if the wear is severe or broken, it needs to be repaired by chrome plating or reworked. When reworking, the requirements of the parallelism and symmetry of the keyway on the long and short axes should be satisfied; the matching clearance between the flat key and the gear keyway installed on the shaft should not be too large; the shaft must not be in the gear bore. Radial oscillation is generated; the coaxiality of the journal and the mating surface of the mounting gear portion shall not exceed 10 μm, and the coaxiality of the journals at both ends shall not exceed 20-30 μm.
Elimination of common faults in gear pumps
At present, CB-B gear pumps are widely used in dump trucks and engineering machinery operating mechanisms. The common faults and troubleshooting methods are described below for reference.