Aiming at the vibration existing in every part of pump unit, the reason of vibration was analyzed. From the pump hydraulic and mechanical design, to the pump installation, operation, maintenance and other aspects of the proposed pump vibration reduction measures. The results show that it is ensured that the structure and size of the pump components and the accuracy are compatible with the hydraulic characteristics of the pump such as no overload; to ensure that the actual operating point of the pump is consistent with the design conditions of the pump; to ensure the consistency of processing accuracy and design accuracy; To ensure the quality of parts and components installed with the consistency of its operational requirements; to ensure the quality of repair and wear parts of the same consistency, can reduce pump vibration. Vibration is an important indicator to evaluate the reliability of pump units. Vibration caused by excessive harm are: vibration caused by the pump unit can not operate normally; lead to vibration of the motor and pipeline, causing machine damage; cause damage to bearings and other parts; resulting in loose connection parts, the basis of cracks or motor damage; resulting in Pump connected to the pipe or valve loose, damaged; the formation of vibration noise. The causes of pump vibration are manifold. The shaft of the pump is generally connected directly with the shaft of the driving motor, so that the dynamic performance of the pump and the dynamic performance of the motor interfere with each other; the rotating parts with high speed, the movable and the static balance are able to meet the requirements; the components with the fluid are greatly influenced by the water flow; The complexity of the fluid movement itself is also a factor that limits the stability of the dynamic performance of the pump. 1 pairs of causes of pump vibration analysis 1.1 Motor motor structure loose, bearing positioning device loosening, iron core silicon steel is too loose, the bearing wear due to decreased stiffness caused by the support, will cause vibration. Eccentric mass, rotor bending or mass distribution problems caused by uneven rotor mass distribution, resulting in static and dynamic balance exceeded Sichuan. In addition, squirrel-cage motor rotor cage cages have broken, causing the rotor suffered magnetic field force and rotor inertia imbalance caused by the imbalance caused by vibration, lack of phase motor, the power supply imbalance and other causes can cause vibration. Motor stator windings, due to the quality of the operation of the installation process, resulting in unbalanced resistance between the phase windings, resulting in uneven magnetic field, resulting in an imbalance of electromagnetic force, the electromagnetic force as the excitation force to cause vibration. 1.2 Basic and pump bracket drive device used between the base and the form of contact fixed is not good, the basis and the motor system absorption, transmission, isolation vibration poor, resulting in vibration of the foundation and motor are exceeded. The pump foundation is loosened or the pump unit forms an elastic foundation during installation or the water pump creates another critical speed difference 1800 from the vibration due to weakening of the foundation stiffness due to the oil blisters which increases the vibration frequency of the pump. Frequency and an external factor frequency close to or equal to, it will increase the pump amplitude. In addition, the foundation anchor bolts loose, resulting in lower restraint stiffness, will make the motor vibration increased. 1.3 Coupling Coupling The connecting bolt's circumferential spacing is bad, the symmetry is destroyed; Coupling plus section eccentricity, will have eccentric force; Coupling cone degree tolerance; Coupling static balance or dynamic balance Not good; elastic pin and the coupling with the tight, so that elastic loss of elasticity of the pin to adjust the function of the coupling can not be well on the center; Coupling and shaft with the gap too large; Mechanical wear and tear caused by coupling with the rubber ring with a decline in the performance of the coupling bolts used on the quality of each other. These causes vibrations. 1.4 impeller ①impeller eccentric mass. Poor quality control during manufacture of the impeller, such as casting quality and machining accuracy, or corrosiveness of the fluid being conveyed, resulting in erosion of the impeller runner resulting in eccentricity of the impeller. ② the impeller blade number, exit angle, wrap angle, laryngeal tongue and impeller exit side of the radial distance is appropriate. ③ between the middle wheel mouth ring and the pump mouth ring, interstage bushing and baffle bushing, from the initial Rub, gradually become mechanical friction and wear, which will aggravate the pump vibration. 1.5 shaft and its auxiliary shaft shaft pump is very long, prone to lack of shaft stiffness, deflection is too large, shaft straightness difference between the situation, resulting in moving parts (drive shaft) and static parts (sliding bearing or mouth ring) between Rub friction, the formation of vibration. In addition, the pump shaft is too long, affected by the impact of the flow of water in the pool larger pump to increase the vibration of the underwater part. Shaft end of the balance plate gap is too large, or axial adjustment of the amount of work properly adjusted, will cause the shaft low-frequency movement, resulting in bearing vibration. Eccentricity of the rotary shaft can cause flexural vibration of the shaft. 1.6 pump selection and variable operating conditions Each pump has its own rated operating point, the actual operating conditions and design conditions are consistent, the dynamic stability of the pump has a significant impact. Pump running in the design conditions relatively stable, but under variable operating conditions, due to the radial force generated in the impeller, the vibration has increased; single pump improper selection, or two models do not match the pump in parallel. These will cause the pump to vibrate. 1.7 bearing and bearing stiffness is too low, will result in lower first critical speed, causing vibration. In addition, the guide bearing poor performance led to bad wear resistance, poor fixing, bush clearance is too large, but also easily lead to vibration; and thrust bearings and other rolling bearing wear, it will make the shaft longitudinal vibration and bending vibration simultaneously aggravate . Improper selection of lubricants, deterioration, excessive levels of impurities and lubrication problems caused by poor lubrication pipes, will cause deterioration of bearing conditions, triggering vibration. Motor self-excitation of the sliding bearing oil film will also produce vibration. 1.8 pipeline and its installation Fixed pump outlet pipe stent stiffness is not enough, the deformation is too large, causing the pipe under the pressure on the pump body, making the pump and the motor neutral damage; pipe during the installation is too big, import and export pipe Road and the pump connection when the internal stress; import and export pipe loose, restraint stiffness decline or failure; all part of the export runner rupture, fragment card impeller; poor pipeline, such as the outlet has a balloon; Did not open; inlet intake, uneven flow field, pressure fluctuations. These causes can directly or indirectly lead to the vibration of pumps and pipes. 1.9 Matching between components The concentricity of the motor shaft and pump shaft is out of tolerance; the coupling between the motor and the drive shaft is used and the concentricity of the coupling is out of tolerance; the dynamic and static parts (such as the impeller Yi Hekou Rings between the design gap wear larger; intermediate bearing bracket and pump cylinder clearance exceeded; ring gap inappropriate, resulting in an imbalance; seal ring around the gap uneven, such as the mouth ring groove or not partition No one groove, it will happen. These negative factors can cause vibration. 1.10 factors pump itself when the impeller rotation asymmetry pressure field generated; suction pool and inlet vortex; impeller inside and the volute, guide vortex vortex occurs and disappears; valve half-open vortex caused by the vibration; as the impeller blades Inadequate distribution of outlet pressure due to limited number; Outflow in impeller; Surge; Pulsation pressure in runner; Cavitation; Water flows in the pump body, which can cause friction and impact on the pump body, The leading edge of the guide vane, causing vibration; high temperature water boiler feed pump prone to cavitation vibration; pump pressure pulsation, the main pump impeller seal ring, pump seal ring gap is too large, causing the pump body leakage loss , Severe backflow, which in turn causes imbalance and pressure pulsation of the rotor axial force, which will increase the vibration. In addition, for hot water pump delivery, if the pump before the start of uneven heating, or pump sliding pin system is not working properly, resulting in thermal expansion of the pump group will trigger the start-up phase of the violent vibration; pump from thermal expansion and so on Of the internal stress can not be released, it will cause the spindle support system stiffness changes, when the stiffness changes and the system angular frequency integral multiple relationship, the resonance occurs. 2 measures to reduce vibration 2.1 from the design and manufacturing process to eliminate vibration 2.1.1 mechanical structure design issues to note 1) the design of the shaft. Increasing the number of bearings supporting the drive shaft, reducing the support spacing, reducing the shaft length in the appropriate range, increasing the shaft diameter, increasing the rigidity of the shaft; when the pump shaft speed gradually increased and close to or integer times the inherent rotor pump Vibration frequency, the pump will be violent vibration, so in the design, should make the natural frequency of the drive shaft to avoid the motor rotor angular frequency; improve the manufacturing quality of the shaft to prevent mass eccentricity and excessive form of tolerances. 2) the choice of sliding bearings. The use of non-lubricated sliding bearings; In liquid hydrocarbons and other chemical pumps, the sliding bearing material should be used with good self-lubricating properties of materials, such as PTFE; In deep well water pumps, diversion bushings choose to fill polytetrafluoroethylene , Graphite and copper powder material, and the rational design of its structure, so that the sliding bearing fixed and reliable; impeller seal ring and the pump seal ring friction coefficient with a small friction pair, such as M20lK a graphite material; limit the maximum speed; increase Bearing bearing capacity and bearing stiffness. 3) Use stress relief system. For the delivery of hot water pump, the design should be caused by the deformation of the pump caused by the structural stress between the connectors can be released, such as the bolt on the pump body to increase the bolt sleeve, to avoid direct and rigid pump body Basic contact. 2.12 hydraulic design considerations 1) Reasonable design of the pump impeller and runner, the impeller cavitation and erosion less occur; a reasonable choice of the number of leaves, the exit angle of the leaves, the blade width, the exit of the exit coefficient and other parameters to eliminate head Curve hump; pump impeller outlet and volute tongue distance, there is information that the value of one-tenth of the outer diameter of the impeller, the minimum pulsating pressure; the blade outlet edge make a dip (for example, made about 20.) , To reduce the impact; to ensure the gap between the impeller and the volute; improve pump efficiency. At the same time, the outlet of the pump and other related flow channel optimization design to reduce the vibration caused by hydraulic losses. Reasonable design of the suction chamber at the inlet section of various pumps and the mechanical structure of the compression stage can reduce the pressure pulse, ensure the flow field stability, improve the working efficiency of the pump, reduce the energy loss, and also improve the vibration dynamic performance of the pump Stability. 2) Cavitation Vibration is a very important part of pump vibration. When the pump population pressure is lower than the corresponding water temperature and pressure, there will be accompanied by severe vibration of the cavitation. Measures to reduce cavitation include: determining the installation height of the pump, making the effective NPSH of the device greater than the minimum NPSH of the pump; appropriately increasing the diameter of the inlet pipe, shortening the length of the inlet pipe, reducing the pipe fittings, Through the flow section of the rate of change to minimize section, to improve the roughness of the pipe wall; reduce the number of elbows and increase the pipe turning angle; reduce the pump speed; using cavitation cavitation materials, such as stainless steel, or prone to steam Corrosion of parts coated with epoxy resin; influent waterway design should be reasonable and strive to smooth, so that the impeller into the impeller flow velocity and pressure distribution, to avoid local low pressure zone; improve the quality of manufacturing and processing, to avoid the inaccurate vane line caused by the local flow rate Too large pressure drop; To improve the anti-cavitation performance of the pump device, including the installation of hydraulic booster at the inlet of the pump, the structure of the booster to improve suction suction head of the pump to improve the pump cavitation Increase the geometric inversion height; try to reduce the water head loss; the use of double suction pump. In order to ensure that there is no accumulation of air in the suction pipe or pressurized water pipe, no part of the suction pipe should be higher than the inlet of the water pump. In order to reduce the pressure pulsation at the manhole, the diameter of the suction pipe should be an order of magnitude larger than the diameter of the pump, so that the flow of water will have a certain contraction at the pump population to make the flow velocity distribution more uniform and at the same time there should be a section ahead of the pump population Straight pipe, straight pipe length of not less than 10 times the diameter of the pipe. Pay attention to create a good water conditions, into the water flow in the pool should be smooth and uniform to eliminate the accompanying Karman vortex vibration. 3) basic design. The basic weight of the pump and motor should be more than three times the sum of mechanical weight; Sheng basins should have considerable strength; motor bracket with the best foundation or made of surface contact; set between the pump and bracket Vibration isolation pad or vibration isolator. In addition, the use of damping material between the pipe connections, reducing pipeline layout, can eliminate elastic contact and hydraulic losses caused by vibration. 2.2 Elimination of vibrations during installation and maintenance 1) Shafts and shafts. Before installation, check whether the pump shaft, the motor shaft and the transmission shaft are bent and deformed, and the quality is eccentric. If yes, it must be corrected or further processed. Check whether the transmission shaft contacting with the guide bearing rubs the bearing bush or bushing due to bending Make yourself excited. If monitoring indicates that the shaft has actually been bent, correct the shaft. At the same time, check the shaft end clearance value, if the value is too large, it shows that the bearing has worn, the need to replace the bearing. 2) impeller. Dynamic and static balance is qualified. 3) Couplings. Bolt spacing is good; elastic pin and the elastic ring combination can not be too tight; Coupling bore and shaft is too loose, if too loose, such as spraying method can be used to reduce the coupling diameter until it reaches The transition fit the required dimensions, and the coupling is then fixed to the shaft. 4) plain bearings. The gap value is in line with the standards; whether the lubrication is good; improve the level of the bearing repair process of the pump, strictly follow the first scraping tile, after grinding, and then scraping the cycle of the program to ensure that the contact area of ​​the bearing bush and journal meet the required standard: ①pump journal and bearing clearance value, by replacing the front and rear bearings, grinding, scraping tile, adjusting and other means to achieve compliance. ② pump bearing body and bearing box spherical top clearance value of qualified. ③ pump shaft bearing shaft bottom and pump shaft journal contact point and contact angle: the standard provisions under tile back and bearing contact area should be 60% or more, journal contact sliding contact surface contact density maintained at 2 per square centimeter A 4 point, the contact angle remains at 60 "a 90". 5) bracket and the floor. Timely find the vibration of the support of the fatigue situation, to prevent because of the decrease of strength and stiffness caused by natural frequency decline. 6) Clearances and wearing parts. Ensure that the motor bearing clearance appropriate; appropriate adjustment of the gap between the impeller and the volute; regular inspection, replacement of the impeller port ring, pump ring mouth, interstage bushing, bushing bushing and other wear parts. 2.3 to eliminate due to the selection of the pump and the vibration caused by improper operation of two pumps in parallel to ensure the same pump performance. Pump performance curve should be slow down as well, can not have hump. Use should pay attention to: Eliminate the cause of the pump overload factors, such as flow blockage; Properly extend the pump start-up time, reduce the disturbance to the drive shaft, reduce the rotating parts and stationary parts between the collision and friction, and the resulting Of the thermal deformation; for water-lubricated sliding bearings, the start-up process should be added to the pre-lubrication of water, to avoid dry start until the water pump to stop after the injection of water; regular need to oil bearing appropriate amount of oil injection; Because there is torsion vibration shaft system, if the use of thrust tile, the damage is mainly thrust tile, then you can properly increase the viscosity of lubricating oil to prevent liquid dynamic lubrication film damage. Finally, in order to prevent the pump amplitude is too large, you can also use the measurement to analyze the vibration conditions to determine the best pump operating parameters. 3 Conclusions The causes of pump vibration include mechanical, hydraulic, and electrical reasons. Vibration control comprehensively reflects the machining process, the level of operation of mechanical installation staff, the quality of the pump operator, the function of hydraulic design software, the performance status of various parts of the material, the performance of monitoring equipment. In practice, to exclude vibration should be combined with experience and theoretical analysis, the vibration mechanism analysis and the actual detection equipment to get the data together. Many vibrations can be eliminated by improving design and installation quality, increasing operating levels, and enhancing routine maintenance. With the development of new material technology and the emergence of new technology, as well as advances in computer technology and numerical methods and the basic theory of fluid mechanics, together with the rise and development of vibration and noise diagnostic techniques, the design, use and maintenance of pumps will surely flourish. , The performance will certainly be optimized day by day, the dynamic performance will also become more and more stable. Search Keyword: More Pump Technology Articles