Created on:2021-12-03 13:31

Use and maintenance of external gear pump

Use and maintenance of external gear pump

(1) Use.

① Generally, the oil suction height of gear pump shall not be greater than 500mm.

② The gear pump shall be directly connected with the motor through the flexible coupling. Generally, it shall not be rigidly connected or connected with the power source through the gear pair or transmission pulley mechanism, so as to avoid unilateral force transmission, which is easy to cause bending of the gear pump shaft, unilateral wear and failure of the pump shaft oil seal.

3) The limit speed of shall be limited. The speed cannot be too high or too low. If the rotating speed is too high and the oil does not have time to fill the whole gap between teeth, cavitation, noise and vibration will occur; The rotating speed is too low to make the pump form the necessary vacuum, resulting in poor oil absorption. At present, the driving speed of domestic gear pump is in the range of 300 ~ 1450r / min. refer to the operation manual of gear pump for specific conditions.

4) CB-B gear pump and some other gear pumps are mostly one-way pumps, which can only be rotated in one fixed direction. When used in the reverse direction, they cannot be oiled, and often make the pump oil seal overturn and break. Therefore, special attention must be paid during use. Otherwise, the oil seal of a new pump will be overturned and broken as soon as it runs. If reverse or two-way rotation is required, special orders shall be made.

(2) Several common maintenance methods.

The damage of the gear pump can not be avoided during use. If it is damaged, it must be repaired. The following takes CBG2 gear pump as an example to talk about its maintenance methods.

According to the structural characteristics of cbgz gear pump such as "three piece structure, fixed side plate and secondary seal" and the practical experience of use and maintenance such as "thin side plate and reversible direction", the following methods can be adopted:

1) Reduced size method. Burns, wear and scratches on the side plate are important causes of axial leakage of CBG2 gear pump (the leakage caused by the damage of the side plate accounts for about 80% of the whole axial leakage). Since the axial clearance (0.05 ~ 0.10mm) between the gear pair and the side plate of CBG2 gear pump is guaranteed by the manufacturer depending on the machining accuracy of the working thickness of the pump body and the width of the gear pair, and the thickness of the side plate has no effect on this clearance, the side plate can be repaired by turning, grinding, grinding and polishing. When the size reduction method is adopted to repair the side plate, the thickness of the remaining bronze sintering layer should be 0.35 ~ 0.50mm.

2) Substitution method. That is, replace the cbgz gear pump with the same displacement on the equipment with serious wear or not performing the task temporarily, or replace the inlet and outlet pipe joints of CBG2 gear pump with different displacement after modification (the installation dimensions of CBG2 gear pumps with different displacement are the same). When using the substitution method, pay attention to whether the rotation direction of the substitute pump is the same as that of the replaced pump. For pumps with different rotation directions, the pump shall be disassembled and the pump body and side plate shall be rotated 180 ° before reassembly.

3) Assembly method. All parts of CBG2 gear pump are universal except gear pair and pump body. Therefore, in the scrapped CBG2 gear pump, some parts that can be used can be disassembled as needed to assemble a complete pump, which can be installed after passing the commissioning.

4) Transposition. As CBG2 gear pump has left-hand and right-hand rotation, gear wear is concentrated on one side of the gear. Therefore, the transposition method can be adopted to exchange the gear pairs with the same displacement to different directions, so that the non worn side of the gear teeth becomes a new meshing surface. If the above conditions are not met, the driven gear of the pump can also be installed in a reverse direction to make the non worn side of the driven gear become a new meshing surface, improve the meshing relationship of the meshing surface and reduce the leakage between teeth. For CBG2 gear pump, transposition method can also be used for two rotary oil seals installed "back-to-back". That is, when the hydraulic oil leakage is caused by the damage of the leaking rotary oil seal, and the dust-proof rotary oil seal is not damaged, the two can be transposed for emergency use.

5) Shrinkage method. The clearance between the inner hole surface of the secondary seal ring and the gear journal in CBG2 gear pump is 0.025 ~ 0.035mm. When the clearance exceeds 0.05mm, the volumetric efficiency of the pump will decrease significantly. In this regard, the hole closing method can be adopted, that is, machining a shrinkage sleeve with an inner diameter 0.05mm smaller than the outer diameter of the sealing ring, and pressing the sealing ring in

After the shrinkage sleeve, it shall be kept at room temperature for 8 ~ 12h or shaped and insulated in a 200 ~ 300 ℃ electric heater for 2 ~ 3H. After taking out the sealing ring, its inner diameter will be reduced by 0.02 ~ 0.03mm, and it can be used after installing the sealing ring (the sealing ring can be repaired by shrinkage method, as shown in Figure q).

6) Chamber sweeping method. The wear of CBG2 gear pump body is concentrated in the low pressure area, as shown in Figure R. When the pump body is worn, the prepared metal glue can be applied to the wear area (the thickness of the metal glue coating is slightly larger than the wear amount). After the metal glue solidifies for 20 ~ 30min, reinstall the gear pair and rotate the gear pair in the pump body. Use the rotation of the gear pair in the pump body to squeeze, scrape and clean the area coated with metal glue. Remove the gear pair, clean all parts, and use it after reassembly.

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