Interpretation of bearing grinding process on the stable operation of shielded electric pump way

[Pump Network in Asia] In the shielded pump test process sometimes encounter such a problem, that is, when the pump starts, the current exceeds the rated current, or starting the current is normal, but as the test pressure increases, the test Current also increases. When this happens, it must be disposed of immediately or the operating condition will lead to increased wear on the bearings and eventually pump damage. Interpretation of bearing grinding process on the stable operation of shielded pump way 1, the traditional way of fault handling for the test process in the test current with the test pressure increases, the phenomenon of the past, the traditional treatment is the use of optional bearing process debugging Electric pump, pump to be stable operation, performance in line with technical requirements, make the factory test. However, this method requires replacement of multiple sets of bearings, production of many spare parts, increased costs, waste and blind replacement, as well as prolonging the test cycle and affecting the scheduled delivery of the product. 2, the operation of shielded electric pump to find the test current increases with increasing pressure reasons, we combined with shielded pump test, has to take to replace the hydraulic components, replacement of housings, replacement of pump body, replacement parts installation orientation, replacement of bearings and The friction pair and other programs, after repeated testing, comparison and analysis of a number of test programs, bearing in-depth investigation of the production process found that the bearing processing accuracy is the key factor affecting the stable operation of shielded electric pump, the bearing is stable operation of shielding Electric pump stable operation of the key factors, this will be the bearing matching process to the electric pump assembly before the bearing grinding process. 2.1, the conditions for stable operation of the bearing Shielded electric pump generally adopts "a push, two-lead" bearing structure, namely the bearing structure is a thrust bearing, two upper and lower guide bearings. The conditions for the stable operation of the bearing friction bearings must form a stable liquid film. In hydrodynamic lubrication process, when the shaft system does not interfere with the formation of dynamic pressure when the liquid film should have the following conditions Yong electric ik fluid that is, the lubricating medium has a certain viscosity. The two friction surfaces, namely the thrust bearing surface and thrust plate surface have a certain relative sliding speed. A converging wedge gap can be formed between two relatively sliding surfaces. Bearing surface roughness and processing accuracy is less than the minimum water film thickness of the safety value. Bearings have a suitable load (specific pressure). Analysis of the above conditions, liquid lubricated shielded pump, have a certain viscosity. Thrust plate with the axis of rotation, have a certain relative speed. Using liquid lubrication, can provide adequate lubrication medium. Bearing design, load bearing allowable PV value of the design. Therefore, the formation of a convergent wedge gap between the two relatively sliding surfaces, the bearing surface roughness and machining accuracy can guarantee the minimum water film thickness of the safety value may be the main reason for the bearing can not be stable operation. 2.2, the production process review (1) the inventory of thrust bearing shape and position tolerance of the inventory of thrust bearings (a total of 33) were inspected, in 2006 June 1 factory, July 2008 32 factory. After testing all bearing inventory deformation, in July 2008 into the plant 11 deformation smaller, in line with the requirements of the drawings, the remaining bearing flatness are ultra-poor, and the general appearance of the cambered face concave disk (see). In 2006 June into the factory bearing larger deformation, face flatness 0.026, non-face flatness 0. 023, the parallelism of the upper and lower surface 0.022. With a knife-edge inspection of the face, the face of light, are visible gaps and light perception, see. Thrust bearing face shape knife-edge detection Thrust bearings (inner ring visible sense) existing stock under thrust bearing position tolerance inspection shows that the majority of the bearing surface deformation convex concave; the same amount of deformation of the same bearing Similarly, bearing individual differences exist. (2) Analysis of the causes of thrust bearing deformation Thrust bearing processing technology: a slice of a sintered resin sintering a drying a roughing (including cutting over the groove) a finishing a fine grinding the upper and lower surface of a working surface polishing. In the impregnated resin, drying and other processes, especially in the process of bearing over-flow groove, the bearing there are internal stress. According to the test and inventory bearing inspection situation, the bearing storage process, due to stress relief will occur deformation; graphite bearings with the ambient temperature and humidity changes will also be deformed. 2.3, the test current increases with the pressure analysis of the thrust bearing surface morphology test results show that the shielding pump bearing surface shape tolerance does not meet the requirements of the drawings, the work surface convex concave (disc-shaped) bearings, friction pair can not The formation of a stable fluid lubrication, resulting in resistance during operation, is the direct cause of fluctuations in the current pump operation. 2.4, the convex concave bearing hazards to the working face of the thrust bearing, friction test at the beginning of the test surface roughness is good, normal start pump, partial friction is running current slightly larger and with a water pressure fluctuations; but With the pump running, the bearing wear friction resistance after the strong role, will lead to abnormal friction friction resistance increases, when the friction torque is equal to the starting torque, but also lead to pump blocked. To ensure that the bearing surface shape tolerance and surface machining accuracy is the key to ensure the stable operation of the bearing. 3, the bearing grinding process to determine the shield pump test process due to bearing accuracy problems caused by the test current increases with the pressure increases the phenomenon, after many trials and commissioning experience to determine the use of bearing grinding process to ensure that the thrust bearing And guide bearing accuracy. General bearing manufacturers use special grinding equipment for bearing face grinding, grinding, the bearing face high precision, to meet the requirements of stable operation of the bearing. However, due to the manufacturer's production conditions are limited, generally adopt manual grinding bearing technology. Manual grinding of bearings, the need to pay attention to the following questions: 3.1, bearing grinding, the first to 100 ° C in hot water to cook to eliminate stress. 3.2, before grinding grinding plate to ultra-flat. 3.3, flatness grinding tooling within 0.01mm. 3.4, to ensure that the parallelism of thrust bearing two face in 3.5 to ensure that the flatness of thrust bearing face within 0.01mm. 3.6, to ensure that the thrust bearing axis and face perpendicularity within. 3.7, after the thrust bearing into the bearing seat thrust bearing bearing relative to the axis of the verticality within 01mm. 3.8, guide bearing grinding rod and guide bearing bore clearance to be prepared to ensure that the size of the grinding line with the provisions of the tolerance. 3.9, guide bearing grinding before, we must check the roundness of the bearing bore to avoid bearing bore a little, this must ensure the accuracy of processing equipment. 3.10, grinding process, the thrust bearing first single grinding, and then with the upper and lower guide bearing for grinding. 4 Conclusion In the operation of shielded pumps, current fluctuations with pressure for the analysis of the phenomenon shows that the bearing processing accuracy is the key to the stable operation of shielded pumps. Through the mechanical testing and testing of the bearing inventory, bearing grinding process and bearing surface machining accuracy, is an effective way to improve the quality of shielded electric pump. (Editor: Huang Nengwen QQ:)