Pump is a necessary and common equipment in water treatment engineering. This knowledge and experience is very important. This article is a collection of 148 technical questions and answers about pump compiled by an engineer who has worked for 19 years. Dry goods are practical!

1. What is a pump?

A: the pump is a kind of machinery that converts the mechanical energy of the prime mover into pumping liquid energy.

2. What is power?

A: the work done per unit time is called power.

3. What is effective power?

In addition to the energy loss and consumption of the machine itself, the liquid gets the actual power through the pump per unit time, which is called effective power.

4. What is shaft power?

A: the power transmitted by the motor to the pump shaft is called shaft power

5. Why is the power transmitted from the motor to the pump always greater than the effective power of the pump?

Answer: 1) when the centrifugal pump is in operation, some high-pressure liquid in the pump will flow back to the inlet of the pump or even leak out of the pump, so some energy must be lost; 2) . when the liquid flows through the impeller and pump shell, the change of flow direction and velocity and the mutual impact between fluids also consume some energy; 3) The mechanical friction between pump shaft and bearing and shaft seal also consumes some energy; Therefore, the power transmitted by the motor to the shaft is always greater than the effective power of the shaft.

6. What is the total efficiency of the pump?

A: the ratio of the effective power of the pump to the shaft power is the total efficiency of the pump.

7. What is the flow of the pump?

What symbol is used? Flow refers to the amount of liquid (volume or mass) flowing through a certain section of the pipeline in unit time. The flow of the pump is represented by "Q".

8. What is the pump head?

What symbol is used? A: lift refers to the increment of energy obtained by fluid per unit weight. The pump head is represented by "H".

9. What are the characteristics of chemical pumps?

Answer: 1). Be able to meet the requirements of chemical process; 2) . corrosion resistance; 3) . high and low temperature resistance; 4) Wear resistance and erosion resistance; 5) Reliable operation; 6) No or little leakage; 7) It can transport liquid in critical state; 8) It has cavitation resistance

10. Common mechanical pumps are divided into several categories according to the working principle?

Answer: 1) vane pump. When the pump shaft rotates, it drives various impeller blades to give centrifugal force or axial force to the liquid to transport the liquid to the pipeline or container, such as centrifugal pump, vortex pump, mixed flow pump and axial flow pump. 2) Positive displacement pump. Pumps that use the continuous change of volume content product of pump cylinder to transport liquid, such as reciprocating pump, piston pump, gear pump and screw pump; 3) Other types of pumps. Such as electromagnetic pump for conveying liquid electric conductor; Pumps that use fluid energy to transport liquid, such as jet pumps, air risers, etc

11. What should be done before the maintenance of chemical pump?

Answer: 1) before the maintenance of machinery and equipment, it is necessary to stop, cool down, relieve pressure and cut off the power supply; 2) Machines and equipment with flammable, explosive, toxic and corrosive media must be cleaned, neutralized and replaced before maintenance. Construction can only be carried out after passing the inspection; 3) For the maintenance of equipment, machines and pipelines with flammable, explosive, toxic and corrosive media or steam, the inlet and outlet valves of materials must be cut off and blind plates must be added.

12. What process conditions should be met before maintenance of chemical pump?

Answer: 1) stop; 2) Cooling; 3) Pressure relief; 4) Cut off the power supply; 5) Displacement

13. What are the general principles of mechanical disassembly?

Answer: Generally speaking, it should be disassembled from the outside to the inside, from the top to the bottom, and the whole parts should be disassembled as far as possible.

14. What causes the power loss in the centrifugal pump?

A: there are three kinds of losses: hydraulic loss, volume loss and mechanical loss. 1) hydraulic loss: when the fluid flows in the pump body, if the flow channel is smooth, the resistance is smaller, and the flow channel is rough, the resistance is larger. When the water enters the rotating impeller or comes out of the impeller, there will be collision and vortex to cause losses. The above two losses are called hydraulic losses. 2) Volume loss: the impeller is rotating, while the pump body is stationary. A small part of the fluid flows back to the inlet of the impeller in the gap between the impeller and the pump body; In addition, some fluid flows back from the balance hole to the impeller inlet or leaks from the shaft seal. If it is a multi-stage pump, part of the leakage from the balance disc shall also be lost. These losses are called volume losses; 3) Mechanical loss: when the shaft rotates, it will rub with the bearing and packing. When the impeller rotates in the pump body, the front and rear cover plates of the impeller will rub with the fluid, which will consume part of the power. These losses caused by mechanical friction will always become mechanical losses.

15. What is the basis for rotor balancing in production practice?

A: static balance method or dynamic balance method can be selected according to different revolutions and structures. The static balance of the rotating body can be solved by the static balance method. Static balance can only balance the imbalance of the center of gravity of the rotating body (i.e. eliminate the torque), but can not eliminate the unbalanced couple. Therefore, static balance is generally only applicable to disk-shaped rotating bodies with small diameter. For the rotating body with large diameter, the problem of dynamic balance is often common and prominent, so it is necessary to deal with the problem of dynamic balance.

16. What is balance? What are the balance categories?

A: 1) the work of eliminating the imbalance of rotating parts or components is called balance; 2) Balance can be divided into static balance and dynamic balance.

17. What is static balance?

A: on some special tooling, the front orientation of the imbalance of the rotating parts can be measured without rotation, and the position and size of the balance force can be determined at the same time. This method of finding balance is called static balance.

18. What is dynamic balance?

A: when the parts rotate through the components, it is necessary to balance not only the centrifugal force generated by the eccentric weight, but also the balance of the couple moment composed of the centrifugal force, which is called dynamic balance. Dynamic balance is generally used for mechanical parts with high speed, large diameter and particularly strict working accuracy requirements. Accurate dynamic balance must be done.

19. How to measure the eccentric orientation of the balanced parts when doing the static balance of rotating parts?

A: first, let the balanced part roll freely on the balance tooling for several times. If the last rotation is clockwise, the center of gravity of the part must be on the right side of the vertical centerline (due to friction resistance). At this time, make a mark with a white chalk at the lowest point of the part, and then let the part roll freely. The last rolling pendulum is completed in the counterclockwise direction, The center of gravity of the balanced part must be located on the left side of the vertical centerline. Similarly, make a mark with a white chalk, and the center of gravity recorded twice is the biased orientation.

20. How to determine the size of the balance weight when doing the static balance of rotating parts?

A: first, turn the eccentric orientation of the part to the horizontal position, and add appropriate weight at the maximum circle at the opposite symmetrical position. This point should be taken into account when selecting the parts for weight addition and weight reduction, and whether the weight can be counterbalanced and reduced in the future. After the weight is added, it still maintains the horizontal position or swings slightly, and then reverse the part 180 degrees to keep it in the horizontal position for several times. After the weight is determined to be unchanged, the weight is taken as the weight below, which determines the gravity of the balance weight.

21. What are the types of mechanical rotor imbalance?

A: static imbalance, dynamic imbalance and mixed imbalance.

22. How to measure the bending of pump shaft?

A: after the shaft is bent, it will cause the imbalance of the rotor and the wear of the dynamic and static parts. Place the small bearing on the V-shaped iron and the large bearing on the roller support. The V-shaped iron or support should be placed firmly. Then support the dial indicator with the stem pointing to the axis, and then slowly rotate the pump shaft. If there is bending, there will be a maximum and minimum reading on the dial indicator every revolution, The difference between the two readings indicates the maximum radial runout of shaft bending, also known as runout. The bending degree of the shaft is half of the runout. Generally, the radial runout of the shaft is not more than 0.05mm in the middle and more than 0.02mm at both ends.

23. What are the three main causes of mechanical vibration?

Answer: 1) structure: caused by manufacturing design defects; 2) Installation: mainly caused by improper assembly and maintenance; 3) Operation: mechanical damage or excessive wear due to improper operation.

24. Why is rotor misalignment an important reason for abnormal rotor vibration and early bearing damage?

A: due to the installation error between rotors, rotor manufacturing, deformation after bearing, environmental temperature change and other factors, poor alignment may be caused. The shaft system with poor rotor alignment changes the actual working position of rotor journal and bearing due to the force change of coupling, which not only changes the working state of bearing, but also reduces the natural frequency of rotor shaft system, Therefore, rotor misalignment is an important reason for abnormal vibration of rotor and early damage of bearing.

25. What is the standard for measuring and rechecking journal ovality and taper?

Answer: measure and recheck the ovality and taper of the journal bearing shaft diameter, which shall meet the technical requirements, and generally shall not be greater than one thousandth of the diameter. The ovality and taper of the shaft diameter of rolling bearing shall not be greater than 0.05mm.

26. What should be paid attention to when assembling chemical pump?

Answer: 1) whether the pump shaft is bent or deformed; 2) Whether the rotor balance meets the standard; 3) Clearance between impeller and pump casing; 4) Whether the compression of mechanical seal buffer compensation mechanism meets the requirements; 5) Concentricity of pump rotor and volute; 6) Whether the center line of pump impeller channel and volute channel are aligned; 7) Clearance adjustment between bearing and end cap; 8) Clearance adjustment of sealing part; 9) Whether the assembly of transmission system motor and speed converter (increase and decrease) meets the standard; 10) Alignment of coaxiality of coupling; 11) Whether the clearance of the mouth ring meets the standard; 12) Whether the tightening force of connecting bolts of each part is appropriate.

27. What is the purpose of pump maintenance? What are the requirements?

A: Purpose: through the maintenance of the pump, eliminate the problems existing after long-term operation. The requirements are as follows: 1) eliminate and adjust the large clearance caused by wear and corrosion in the pump; 2) Eliminate dirt, dirt and corrosion in the pump; 3) Repair or replace unqualified or defective parts; 4) The rotor balance test is qualified; 5) Check the coaxiality between the pump and the driver and meet the standards; 6) The commissioning is qualified and the data are complete to meet the process production requirements.

28. What are the reasons for excessive power consumption of the pump?

Answer: 1) the total head is inconsistent with the pump head; 2) The density and viscosity of the medium are inconsistent with the original design; 3) The pump shaft is inconsistent or bent with the prime mover axis; 4) There is friction between the rotating part and the fixed part; 5) Impeller ring is worn; 6) Improper installation of seals or mechanical seals.

29. What are the causes of rotor imbalance?

A: 1) manufacturing error: uneven material density, different axiality, non roundness and uneven heat treatment; 2) Incorrect assembly: the centerline of the assembly part is different from the axis; 3) Rotor deformation: uneven wear, shaft deformation under operation and temperature.

30. What is a dynamically unbalanced rotor?

A: there is a rotor with equal size, opposite direction and unbalanced particles integrated into two couples not on a straight line.

31. How to prevent evacuation and cavitation during operation?

A: evacuation: there is gas and liquid in the pump, the pump cannot work, and the flow and pressure tend to zero. Cavitation: it occurs in the running pump and comes from the change and decrease of medium, flow and pressure in the pump, resulting in hydraulic impact. Generally, pump evacuation refers to a cavitation phenomenon in the pump. Evacuation caused by suction gas due to leakage of installation technology pipeline is rare, and most of them are caused by operation and process changes. In the process of operation, we should start with stabilizing the process operating conditions. The lower limit should be taken for the operating temperature and the lower limit should be taken for the pressure. In order to avoid or control cavitation, the flow of the pump should be moderate during operation and try to reduce large changes in pressure and temperature. The suction pipeline of the pump shall prevent the retention of gas, and the inlet of the standby pump with negative pressure on the inlet pressure shall be closed.

32. What are dynamic fit and static fit? What is the obvious difference between them?

Answer: 1) dynamic fit: the actual size of the hole is larger than the actual size of the pump; 2) Static fit: the fit composed of the actual size of the shaft greater than the actual size of the hole; 3) Obvious difference: with dynamic fit, the shaft can move relative to the hole; Static fit: there is no relative movement between the shaft and the hole.

33. What are the four basic requirements for equipment maintenance?

Answer: neat, clean, lubricated and safe

34. What is the working principle of labyrinth seal?

Answer: labyrinth seal: it is composed of several annular sealing teeth arranged in turn. A series of throttling clearance and expansion space are formed between the teeth and the rotor. The fluid passes through many tortuous channels and generates great resistance after multiple throttling, making it difficult for the fluid to leak and achieve the purpose of sealing.

35. What is interchangeability of parts? What is the main function?

Answer: 1) the parts can be exchanged and used with each other, and can meet the index requirements of the original parts, which is called the interchangeability of parts. 2) It mainly plays a role in facilitating maintenance, reducing maintenance time, improving equipment utilization and working efficiency.

36. What is a power pump?

Answer: the power pump continuously transmits energy to the liquid to be transported, so that its velocity kinetic energy and pressure energy potential energy are increased, mainly by increasing the velocity, and then reducing its velocity, so that most of the kinetic energy is transformed into pressure energy, which is transported by using the increased pressure of the liquid to be transported, such as: 1) vane pump, which includes centrifugal pump, mixed flow pump, axial flow pump, vortex pump, etc; 2) Jet pump, including gas jet pump, liquid jet pump, etc.

37. What is a positive displacement pump?

Answer: in the process of periodically changing the volume of the pump chamber, the positive displacement pump transmits the capacity to the liquid to be transported with the periodic change of action and displacement, so that the pressure can be directly increased to the required pressure value to realize the transportation, such as: 1) reciprocating pump, including piston pump, plunger pump, diaphragm pump, extrusion pump, etc; 2) Rotor pump, including gear pump, screw pump, roots pump, rotary piston pump, sliding vane pump, crankshaft pump, flexible rotor pump, peristaltic pump, etc.

38. What are the main performance parameters of the pump?

Answer: it mainly includes: flow, head, NPSH, speed, power and efficiency.

39. Why do you turn the standby equipment regularly? What should I pay attention to when turning?

Answer: 1) regularly turn the standby equipment. First, check whether the equipment operates flexibly and whether there is jamming; Second, prevent the bearing from bending and deformation, and really play a standby role. 2) Attention shall be paid during turning: first, the stop position of the rotor after turning forms an angle of 180 degrees with the original position; Second, oil shall be supplied to the pump for oil rejection lubrication, and then turning shall be carried out to prevent damage to the bearing.

40. What harm does exceeding the rated current do to the pump?

A: the rated current is the current that the motor normally does work under the rated voltage and rated power. If the rated current is exceeded, the motor is easy to overheat and the relay protection device acts to stop the pump. If the relay protection device does not act or acts poorly, it is easy to burn the motor and damage the pump.

41. What are the main contents of pump patrol inspection?

Answer: 1) check whether the indicated values of pressure gauge and ammeter are in the specified area and remain stable; 2) Check whether the operation sound is normal and whether there is noise; 3) Whether the temperature of bearing and motor is normal (no more than 60 ℃); 4) Check whether the cooling water is unblocked, whether the packing pump and mechanical seal leak, if the leakage is within the allowable range; 5) Check whether the connecting parts are tight and whether the anchor bolts are loose; 6) Check whether the lubrication is good and whether the oil level is normal;

42. What should the device operator do when the maintenance personnel are on duty for maintenance?

Answer: 1) check whether the maintenance work ticket is consistent with the actual equipment tag number to be repaired; 2) Contact the shift leader to find the electrician in the special area to cut off the power; 3) Provide maintenance personnel with equipment damage and specific maintenance parts; 4) Cooperate with the maintenance on site and supervise the maintenance quality; 5) After maintenance, contact power transmission and commissioning; 6) After normal operation, report to the shift leader and make records at the same time.

43. What is the function of pump inlet and outlet valves?

Answer: 1) the pump inlet valve is a component that separates or cuts off the slurry pump from the system during maintenance. It cannot be used to adjust the flow and should be fully opened; 2) The outlet valve is a component for regulating the flow and isolating and cutting off the pump from the system during startup and shutdown maintenance.

44. What is the basis for selecting seals for pumps used in chemical production?

Answer: the rotation speed shall be selected according to the process conditions, working pressure, medium corrosion conditions.

45. What are the types of flat gasket seals?

Answer: 1) non metallic gasket; 2) Non metallic and metal composite gasket seal; 3) Metal gasket seal.

46. What are the main reasons for gasket leakage?

Answer: 1) leakage caused by design; A. improper selection of flange and flange sealing surface; B) improper gasket selection; C. improper selection of flange and bolt materials; 2) Leakage caused by manufacturing, installation and operation; A the machining accuracy of flange and gasket does not meet the technical requirements; B) improper operation when tightening bolts, resulting in offset of gasket; C. the flange sealing face is clean and free of impurities.

47. What is a mechanical seal?

A: mechanical seal, also known as end face seal, is a device to prevent fluid leakage by making the two end faces closely fit and slide relatively under the action of fluid pressure and compensation mechanism.

48. How many sealing forms are commonly used for pumps?

A: there are two kinds, dynamic seal and static seal.

49. What are the main causes of mechanical seal leakage?

Answer: 1) there is excessive wear on the sealing face between the moving ring and the stationary ring, and the load coefficient is unreasonable in the design, resulting in cracks, deformation and damage on the sealing face. 2) Several auxiliary sealing rings have defects or defects caused by improper assembly, and the selection of auxiliary sealing ring is not suitable for working medium. 3) The spring preload is insufficient or after long-term operation, fracture, corrosion, relaxation and coking occur, and the suspended particles or crystals of the working medium accumulate and block in the spring gap for a long time, resulting in spring failure, the compensation seal ring cannot float and leakage; 4) Because the perpendicularity deviation between the dynamic and static ring sealing end faces and the shaft centerline is too large, the sealing end faces are not tightly bonded, resulting in leakage; 5) Due to the large axial displacement of the shaft and the poor coordination or quality of accessories related to the seal, leakage is easy to occur.

50. What is the material of mechanical seal friction pair selected according to?

A: it should be selected according to the nature of the medium, working pressure, temperature, sliding speed and other factors. Sometimes, the ability to withstand short-time dry friction during startup or liquid film damage should be considered.

51. What are the effective ways for labyrinth seal to increase medium resistance?

Answer: 1) reduce the clearance, 2) strengthen the vortex, 3) increase the number of sealing teeth, and 4) try to convert the kinetic energy of the air flow into heat energy

52. What is the working principle of floating ring seal?

Answer: the floating ring seal is based on the throttling effect generated in the narrow gap between the shaft and the floating ring, and the sealing oil higher than the gas pressure is injected into the gap to seal the gas.

53. What is the reason for the increased leakage of floating ring seal?

Answer: 1) the floating ring has been used for a long time and is normally worn, which increases the clearance; 2) The bushing surface of the floating ring hole is rough, the accuracy is low, and the clearance increases due to short-time wear; 3) Improper assembly results in deflection and falling off of centering accessories, resulting in oil flowing out of other gaps, which is due to increased leakage;

54. What is the function of oil baffle? How to measure and adjust the oil baffle clearance?

Answer: 1) the oil baffle is used to prevent the bearing lubricating oil from flowing to the outside of the bearing along the journal. There are two installation positions of the oil baffle: one is on the bearing seat and the other is on the bearing bush; 2) The oil baffle clearance can be measured with a measuring ruler when the oil baffle is disassembled or assembled. For the bearing bush, the oil baffle clearance can be relaxed appropriately. The requirements for the oil baffle clearance facing the bearing seat are relatively strict. Generally, the lower part is required to be 0.05-0.10mm, the two sides are required to be 0.10-0.20mm, and the upper part is required to be 0.20-0.25mm.

55. What are the factors affecting the labyrinth seal?

Answer: 1) the radial clearance is too large, or the clearance of the newly replaced gas seal ring is too small; 2) The sealing plate or gas seal ring and teeth become blunt due to wear, or deform after heating due to long-term wear, resulting in damage and can not be used; 3) After long-term use, the spring becomes loose and deformed, so that the gas seal ring can not be in place. After operation, the precipitation and accumulation of dust and dirt is that the sealed medium pressure is lower than the working medium pressure or the pressure is unstable.

56. What are the common types of dynamic seals?

Answer: cup seal, expansion ring seal, screw seal, pneumatic seal, hydraulic seal, centrifugal seal, packing seal, labyrinth seal, mechanical seal, etc.

57. What are the main factors affecting sealing?

Answer: 1) seal quality, 2) process operation conditions, 3) assembly and installation accuracy, 4) host accuracy, 5) seal auxiliary system

58. What are the components of mechanical seals?

Answer: mechanical seal consists of static ring, moving ring, compensation buffer mechanism, auxiliary seal ring and transmission mechanism. The end faces of the stationary ring and the moving ring are perpendicular to the axis of the pump and fit each other to form a rotating sealing surface. The stationary ring and gland, the moving ring and the shaft are sealed with auxiliary sealing rings to compensate the buffer mechanism, promote the sealing ring to move along the axial direction, keep the end face of the moving ring and the stationary ring close, and compensate the wear of the end face of the sealing ring.

59. What are the characteristics of mechanical seals?

A: 1) good sealing performance. The leakage of mechanical seal is generally 0.01-5ml/h. According to special requirements and special design, the leakage of manufactured mechanical seal is only 0.01ml/h or even less, while the leakage of packing seal is 3-80ml / h (according to relevant regulations of our country, when the shaft diameter is not greater than Φ Less than or equal to 3ml / h when 50mm, and when the shaft diameter is equal to Φ Less than or equal to 5ml / h at 50mm); 2) Long service life, generally more than 8000h; 3) The friction power is small, only 20% - 30% of that of packing seal; 4) There is no relative movement between the shaft and the shaft sleeve and the seal, no friction, and the service life of the shaft and the shaft sleeve is long; 5) The sealing surface of the mechanical seal is perpendicular to the pump axis. When the pump shaft vibrates, the seal will displace at any time, so it can still maintain good sealing performance when the vibration is within a certain range; 6) The mechanical seal relies on the pressure of the sealing fluid and the spring force to keep the sealing surfaces of the static and dynamic rings fit, and compensates the wear amount by relying on the spring force. Therefore, once the allocation is appropriate, the pump generally does not need to be adjusted frequently during operation, which is convenient to use and has a small maintenance workload; 7) It can be used in a wide range of working conditions, such as high temperature, low temperature, high pressure, high speed and strong corrosion; 8) Troubleshooting and parts replacement are inconvenient, and maintenance can only be carried out after shutdown; 9) Complex structure, high assembly accuracy, and certain technical requirements for assembly and installation; 10) High manufacturing price

60. What are the main characteristic parameters of mechanical seal?

Answer: 1) shaft diameter: the range of shaft diameter of pump mechanical seal is generally 6-200mm, especially 400mm. The shaft diameter of pump is usually determined according to the strength requirements, rounded or modulated with shaft sleeve to meet the standard shaft diameter of mechanical seal; 2) Speed: generally the same as the speed of the pump. Generally, the speed of the centrifugal pump is less than or equal to 3000r / min; High speed centrifugal pump ≤ 8000r / min, special pump ≤ 4000R / min; 3) Average circumferential speed of sealing surface: refers to the circumferential speed of the average diameter of sealing end face. The average linear velocity of the sealing surface has a great impact on the heating and wear of the sealing surface (i.e. friction pair). Generally, the circumferential linear speed of receiving and unloading seal is less than or equal to 30m / S; The circumferential linear speed of spring static mechanical seal shall be less than or equal to 100M / S; Special up to 150m / S; 4) End face specific pressure: end face specific pressure PC is the contact pressure borne by the sealing surface (MPA). The specific pressure of the end face of the end face seal shall be controlled within a reasonable range. Too small will reduce the sealing performance, and too large will aggravate the heating and wear of the sealing surface. Reasonable end face specific pressure value of mechanical seal for pump: built-in mechanical seal, generally PC = 0.3-0.6mpa; External type, PC = 0.15-0.4mpa. When the lubricity is good, the specific pressure of the end face can be appropriately increased. For the liquid with high viscosity, the specific pressure of the end face can be increased, which can be PC = 0.5-0.7mpa. For the liquid with volatile and poor lubricity, the specific pressure of the end face should be smaller, which can be PC = 0.3-0.45mpa.

61. What are the inspection contents before mechanical seal assembly?

A: 1) general inspection: mainly inspect the model, specification, performance, matching size of each part and whether there are gaps, pits, deformation, cracks and other damages. 2) Inspection of dynamic and static rings: the sealing end face shall be smooth and bright, with defects such as edge collapse, pits, grooves and scratches. For the graphite ring, check whether there are cracks.

62. How to check the parallelism, perpendicularity and surface roughness of the end face?

Answer: 1) the flatness of end face is 0.0006-0.0009mm for liquid medium and 0.0001-0.0004mm for gas medium; 2) Tolerance of balance: the parallelism deviation between the sealing end and the contact surface of the sealing ring is generally less than or equal to 0.04mm. The parallelism deviation of both ends of the insert ring (ceramic ring and cemented carbide ring) shall be less than or equal to 0.03mm; 3) Perpendicularity tolerance; For the perpendicularity deviation of the outer diameter center line facing the installation of the sealing ring, the full diameter shall be less than or equal to 0.03mm; 4) Surface roughness: hard material on the sealing surface (obtained by removing the material), dark glossy surface (obtained by grinding), soft material (obtained by removing the material) can't see the machining trace, micro identify the machining direction (obtained by grinding and finishing), and the contact with the auxiliary sealing ring (obtained by removing the material) can't see the machining trace, micro identify the machining direction (obtained by grinding and fine turning), and the rest are (obtained by removing materials) slight knife marks (obtained by knife twisting and fine turning).

63. What are the requirements for the inspection of auxiliary sealing ring of mechanical seal?

Answer: 1) the surface of the auxiliary sealing ring shall be smooth and flat without bubble, crack, notch and other defects; The end face size shall be uniform; The burr of the "O" seal ring should preferably form an angle of 45 degrees with the working surface; 2) The hardness of the auxiliary sealing ring shall be selected according to the pressure. The sealing pressure is high and the hardness is high; If the sealing pressure is low, the hardness is low. Synthetic rubber is commonly used for auxiliary sealing ring; 3) The inner diameter of the "O" shaped sealing ring sealing the cylindrical surface shall be 0.5-1mm smaller than the outer diameter of the sealing point. The inner diameter of the "O" ring of the moving ring is relatively small, and the inner diameter of the "O" ring of the stationary ring is smaller than that of the stationary ring; 4) The compression amount of the auxiliary seal shall be appropriate. If the compression amount is too large, the sealing effect is good, but the friction resistance is large, the assembly is difficult, and the swimming compensation ability is poor. The compression is too small, the friction resistance is small, the assembly is easy, but the sealing effect is poor. The "O" rings of the dynamic and static rings of mechanical seals are cylindrical seals, and their compression is about 8% - 23% of the cross-sectional smooth surface diameter. The smaller the diameter, the higher the percentage; The larger the diameter, the smaller the percentage. 5) Other functions shall be considered for the compression of the "O" ring. For example, for the static ring without anti rotation pin, the static ring "O" ring plays a dual role of sealing and anti rotation, and the compression of the "O" ring shall be larger to avoid the rotation of the static ring and seal failure. On the premise of ensuring the sealing effect, the compression amount of the "O" shaped sealing ring of the moving ring shall be smaller, so as to avoid too large compression and too large resistance to float compensation.

64. What does the inspection of mechanical seal spring include?

Answer: spring inspection includes: total number of turns, effective number of turns, free height, whether the axis is perpendicular to the end face, and spring rotation direction. However, the rotation direction of the spring must be checked, and the rotation direction of multiple springs does not need to be checked. The original free height of the new spring shall be checked, and the free height shall be measured and compared with the original records. If the residual deformation is too large, it shall be replaced. After the old spring is cleaned, measure its elasticity, and replace it if the elasticity decreases by 20%. For multi spring mechanical seal, the free height difference of each spring shall not be less than 0.5mm.

65. What are the requirements for the inspection of shaft and shaft sleeve before the installation of mechanical seal?

Answer: 1) check the fit size, surface roughness, chamfer, axial displacement and radial runout of the shaft (or shaft sleeve). If there is a shaft sleeve, check the fit clearance between the shaft and the shaft sleeve. The surface roughness of the installed mechanical seal shaft diameter (or shaft sleeve) shall be less than 1.6, and the axial displacement of the shaft shall not be greater than 0.25mm. The shaft sleeve shall not move axially, and the radial circular jump of the shaft or shaft sleeve is allowed, as shown in the figure:

2) Check the wear of shaft and shaft sleeve. Because of the mechanical vibration and the compensation floating of the moving ring, the shaft and shaft sleeve may also be worn by the "O" seal ring. If they are worn, they shall be flattened, polished or replaced; 3) The shaft sleeve seat and shaft sleeve shall be intact

66. What are the inspection contents of sealing face or sealing box?

Answer: the roughness of the surface in contact with the stationary ring seal ring is 1.6. After the stationary ring is assembled, the circular runout of the end face shall not be greater than 0.06mm. The sealing end face or sealing cavity shall be free of burrs, and the chamfer radius shall be too sufficient and smooth. The inner diameter of sealing face or sealing cavity shall meet the requirements.

67. What is the "six fixed" content of pump patrol inspection?

Answer: check according to the route, person, time, fixed point, responsibility and requirements.

68. How many types of maintenance are there for chemical pump maintenance?

Answer: there are three main forms: 1) maintenance and overhaul, 2) unplanned overhaul and 3) planned overhaul.

69. Precautions for assembling auxiliary sealing ring?

Answer: 1) the auxiliary rubber sealing ring shall not be soaked and washed with gasoline and kerosene to avoid swelling, deformation and premature aging; 2) The "O" seal ring shall be installed on the stationary ring assembly, which shall be smooth and not twisted. It is on the cross section when the burr is free; 3) When pushing the assembly, prevent damage to the "O" ring. The main damage forms are: falling block, crack, bruise, crimping and distortion.

70. What are the reasons for the "O" ring crack of mechanical seal?

Answer: the shaft surface is rough or burred; The old shaft or shaft sleeve was jacked by the fastening screw and was not polished smoothly before assembly; The edges of keyway and anti rotation pin groove are not properly trimmed.

71. What are the requirements for mechanical seal spring compression commissioning?

A: the mechanical seal spring is compressed by a certain amount of the transmission screw, which is called the compression of the spring. After all mechanical seals are installed, another amount is compressed relative to the spring, which is called the compression amount of mechanical seal. The total compression of the mechanical seal spring is the sum of the compression of the transmission screw and the elastic force of the spring itself. During assembly, the greater the compression of the mechanical seal, the smaller the force of the spring on the moving ring. Therefore, the working principle of mechanical seal and the size of spring have a great impact on the performance and service life of mechanical seal, so the compression must be adjusted according to the technical requirements.

72. What are the precautions when installing the stationary ring assembly?

Answer: 1) insert the inspected stationary ring seal ring from the tail of the stationary ring, and install the stationary ring assembly into the gland or sealing cavity. Under no circumstances shall impact force be applied to mechanical seal parts or components. The pressed surface shall be padded with clean paperboard or cloth to avoid damaging the sealing end face. 2) After assembling into rotating ring assembly or stationary ring assembly, press the compensation ring manually to check whether it is installed in place and flexible; Whether the elastic opening is positioned reliably. 3) Whether the perpendicularity between the sealing end face and the center line of the shaft or shaft sleeve meets the requirements. 4) For the static mechanical seal, the anti rotation pin lead of the static ring assembly shall be accurate. When pushing the static ring group, the pin groove of the assembly shall be aligned with the pin. After pushing in place, measure the distance from the end face of the assembly to an end face of the sealing cavity to judge whether it is installed in place; 5) When tightening the bolts to compress the end cover, the force shall be uniform and symmetrical, and it shall be tightened several times. It shall not be tightened at one time to avoid deflection and even crushing the graphite ring.

73. What are the requirements for inspection after mechanical seal assembly?

A: after the mechanical seal is assembled, it shall be inspected twice. 1) Turning inspection. As it has not been filled with liquid, there is only a small amount of lubricating oil on the sealing face of the dynamic and static ring, so it is not suitable to turn more than once to avoid damaging the sealing face. 2) Liquid filling inspection. Check whether there is leakage. If there is no leakage, conduct commissioning inspection.

74. What is the inspection standard for the leakage point of the dynamic seal?

Answer: 1) the packing sealing point shall not be more than 15 drops per minute; 2) No leakage is allowed at the initial stage of mechanical sealing point, and no more than 15 drops per minute at the final stage; 3) Micro leakage is allowed for gear oil pump, which shall not exceed 1 drop per minute; 4) Micro leakage is allowed for various oilers, which shall not exceed 1 drop per minute.

75. What are the requirements for the filling of flange packing?

Answer: 1) the filler shall be cut at an angle of 45 degrees, the notch shall be connected and pressed up and down the tower, and the fractures of two adjacent circles shall be staggered at an angle of about 90 degrees; 2) The packing shall not be pressed too tightly. The gland bolts shall be symmetrically closed and pressed evenly. The pressed gland depth is generally the height of one circle of packing, but not less than 5mm.

76. What preparations should be made before mechanical installation of packing?

Answer: 1) selection of filler: it shall be selected according to the form of filler and the pressure, temperature and corrosion performance of medium. The medium, form, size and performance of filler shall meet the requirements and standards of equipment; 2) Before packing installation, the packing box shall be cleaned, inspected and repaired, and the damaged parts shall be replaced; 3) Check the fit clearance between shaft, gland and packing.

77. What are the types of lubrication?

Answer: 1) drip lubrication, 2) oil mist lubrication, 3) splash lubrication, 4) pressure lubrication, 5) dry oil cup lubrication;

78. What factors should be considered when selecting lubricating oil?

Answer: 1) motion speed, 2) motion property, 3) working temperature, 4) pressure relationship, 5) mating property of friction surface, 6) surface roughness

79. What are the functions of lubricants?

Answer: 1) cooling, 2) rust prevention, 3) cooling, 4) flushing, 5) friction control, 6) wear reduction, 7) vibration reduction, 8) sealing;

80. Where are calcium base grease, sodium base grease and lithium base grease applicable?

A: 1) calcium base grease: water resistant, can be used in wet working places, but not high temperature resistant, and the temperature range is - 10 ~ 60 degrees; 2) Sodium base grease: high temperature resistant, but not water resistant, with the temperature range of - 10 ~ 110 degrees; 3) Lithium base grease: it has heat resistance and water resistance, and the temperature range is - 20 ~ 1200 ℃.

81. What are the "five decisions" of pump lubricating oil management?

Answer: the pump should be fixed, fixed, fixed quality, fixed quantity and fixed person, and check and refuel to ensure the normal operation of the pump;

82. What is the basic principle of the importance of lubrication to the pump?

A: the lubricant can be firmly attached to the friction surface of the machine part to form an oil film. This oil film is strongly combined with the friction surface of the machine part. The two lubrication surfaces are separated by the lubricant, so that the friction of the machine part becomes the friction of lubricant molecules, so as to reduce friction and wear and prolong the service life of the machine part.

83. What are the reasons for oil leakage of oil lubricated pump?

Answer: 1) the oil level is too high and oil leaks along the inner holes of the bearing covers at both ends of the bearing box; 2) The static sealing point leaks oil, such as the oil drain wire is blocked; 3) Oil leakage on the joint surface of bearing gland and bearing;

84. What role does the lubricant play in the rotation of the bearing?

Answer: 1) lubrication, 2) cooling, 3) washing, 4) rust prevention, 5) sealing, 6) cushioning and damping, 7) anti friction and wear;

85. What are the main properties of lubricating oil?

Answer: acid value, viscosity, viscosity index, flash point, mechanical impurities, freezing point, residual carbon and ash.

86. How many methods are there to measure the clearance of journal bearing?

How to use the shaft lifting method to measure? A: there are three common methods: lead pressing method, shaft lifting method and false shaft method. Shaft lifting method: install a dial indicator at the position where the shaft diameter is close to the bearing bush, and then install a dial indicator at the top of the upper shell of the bearing bush for monitoring. Gently lift the shaft diameter until it contacts the upper bush, but do not make the upper bush shell move too much. At this time, the bearing bush clearance is the reading of the dial indicator on the shaft diameter minus the movement of the upper bush shell.

87. What are the faults of sliding bearing? How to deal with it?

A: fault: gluing. Treatment measures: 1) ensure correct installation position and clearance requirements, and 2) ensure good lubrication of rotor. Fault: fatigue rupture. Treatment measures: 1) the bearing surface shall be smooth, and 2) ensure good balance of the rotor. Problem: wear. Treatment measures: 1) avoid insufficient lubrication, 2) clean the lubrication system in time. Problem: scratch. Treatment measures: 1) prevent instantaneous oil cut-off, 2) avoid collision during installation or disassembly. Fault: galling. Treatment measures: pay attention to the cleanness of oil circuit to prevent dirt from entering. Fault: pitting. Treatment measures: 1) increase the oil supply pressure, 2) modify the shape of bearing bush oil groove and oil groove, and 3) reduce the bearing clearance. Fault: electric erosion. Treatment measures: 1) ensure that the insulation condition and protective device of the machine are in good condition, 2) ensure that the machine is well grounded; 3) Check the shaft diameter. If there are electric corrosion pits on the shaft diameter, polish the shaft diameter to remove the pits.

88. What are the reasons for the gluing phenomenon of sliding bearing in use?

Answer: 1) the bearing is overheated, 2) the load is too large and the oil quantity is insufficient, 4) the operation is improper or the temperature control fails.

89. What are the reasons for the abnormal sound of rolling bearing during operation?

Answer: 1) the rolling element or raceway is seriously stripped and the surface is uneven. 2) Improper installation of bearing accessories, looseness or friction. 3) There are iron filings or dirt in the bearing. 4) Lack of lubricant.

90. What are the radial clearances of rolling bearings?

Answer: 1) original clearance: the clearance in free state before bearing installation. 2) Fit clearance: the clearance after the bearing is installed on the shaft or in the hole. Its size is determined by the interference. The fit clearance is less than the original clearance. 3) Working clearance: due to the structural characteristics of some bearings, the clearance can be determined by adjusting the mutual position of bearing rings during assembly or use, such as centripetal thrust ball bearings.

91. What should be paid attention to when selecting rolling bearings?

Answer: 1) direction and nature of load. 2) Requirements for centering performance. 3) Bearing speed. 4) Economy. 5) Accuracy.

92. How to select the lubrication mode of rolling bearing?

A: the normal operation of the bearing is related to lubrication. Dry oil lubrication is adopted when the temperature of the transmitted medium is 80 ℃ and the speed is below 2950r / min; When the temperature of the conveying medium exceeds 80 ℃ and the power is high, thin oil lubrication is adopted.

93. How to check the quality of rolling bearings?

Answer: there shall be no spots, holes, dents, peeling and peeling on the surface of the rolling element and raceway. The rotation shall be flexible. After rotating by hand, it shall be stable, slow down and stop gradually, without sudden stop and vibration. There shall be a certain clearance between the cage and the inner and outer rings. The isolation frame can be pushed radially by hand for experiment. The clearance shall be within the standard range and measured by lead pressing method.

94. What should be paid attention to when disassembling the rolling bearing?

Answer: 1) the force application position should be correct. The principle is to play the inner ring with the shaft and the outer ring with the shell to avoid the stress deformation or bruise of the rolling element and raceway. 2) The force shall be applied symmetrically. Do not hit only one side, causing bearing deflection and gnawing the journal. 3) Before disassembly and assembly, the shaft and bearing shall be cleaned without rust, scale, burr, etc.

95. What happens if there is too much oil in the bearing housing?

A: too much oil is filled in the bearing box, and the bearing has no heat dissipation space, which will cause bearing heating.

96. How to check the radial clearance of rolling bearings?

Answer: the lead pressing method and feeler gauge method are used for measurement. The radial clearance is not marked in the bearing code. The clearance of the bearing varies according to its inner diameter. It is determined by looking up the table. In general, the radial clearance of the rolling bearing shall not be greater than 3 ‰ of the inner diameter of the bearing, and the radial clearance of the centripetal short circular column bearing shall not be greater than 2 ‰ of the inner diameter of the bearing.

97. Why should the rolling bearing be preloaded?

A: when assembling the centripetal thrust ball bearing or the centripetal ball bearing, if a certain axial load is applied to the inner and outer rings of the bearing, the inner and outer rings will move relatively, eliminating the gap between the inner and outer rings and the rolling element, resulting in initial elastic deformation. Preloading can improve the rotation accuracy and service life of the bearing and reduce the vibration of the shaft.

98. How to realize the preload of rolling bearing?

Answer: 1) use the thickness difference between the inner and outer backing rings of the bearing to realize pre tightening. 2) The spring is used to realize the preload, and the spring acts on the outer ring of the bearing to realize the preload of the bearing. 3) Grind the inner ring or outer ring used in pairs to achieve pre tightening. 4) Adjust the axial position of the inner ring of the bearing conical hole to realize preloading.

99. What is the substitution principle of rolling bearing?

Answer: 1) the working capacity coefficient and allowable static load and other technical parameters of the bearing shall be equal to or higher than the technical parameters of the original bearing as far as possible. 2) The allowable limit speed shall be selected to be equal to or higher than the actual speed of the original bearing. 3) The accuracy grade of the substitute bearing shall not be lower than that of the original bearing. 4) The dimensions shall be the same, and the matching dimensions of the machine and the bearing shall not be changed at will due to the replacement of the bearing. 5) For the bearing with nested method, the concentricity of the nested inner and outer cylindrical surfaces shall be ensured, and the tolerance and fit shall be correctly selected.

100. What are the fixing methods of rolling bearings?

Answer: 1) unilateral stress two-way fixation, 2) bilateral stress single fixation, #) mixed fixation

101. What determines the bearing oil level?

A: for rolling bearings, the lowest ball centerline of the bearing is the normal oil level, the lower third of the ball is the low oil level, and the upper two-thirds of the ball centerline is the high oil level. For the lubrication device with the main shaft as the oil slinger, the diameter of the oil ring is generally 1.5-2 times that of the lubricated main shaft. The oil level in the oil chamber shall be a certain distance from the main shaft oil, which is generally one-half of the diameter of the main shaft or the high oil level is about 5mm away from the lower part of the bearing bush.

102. Why is it not good for the bearing oil level to be too high or too low?

Answer: 1) the oil level of the bearing is too low, so some parts of the bearing cannot be lubricated, so the bearing will be worn and heated, causing the bearing to burn out. 2) The oil level is too high. With the rotation of the main shaft, the rolling bearing and oil ring are easy to leak oil from the shaft seal in the process of oil; The oil level is too high, which also hinders the rotation of the oil ring and causes bearing heating.

103. What are the requirements for oil filling of bearings lubricated with grease?

Answer: 1) for machinery with low speed (below 1500r / min), the oil filling amount is generally not more than two-thirds of the whole bearing chamber; 2) For machinery with revolutions above 1500r / min, the oil filling amount shall not be more than half of the whole bearing chamber.

104. What are the reasons for high bearing temperature?

Answer: 1) the oil level is too low and the amount of oil entering the bearing is reduced. 2) Unqualified oil quality, water or impurities, oil emulsification and deterioration; 3) The oil ring does not rotate and the oil supply to the bearing is interrupted. 4) The bearing cooling water is insufficient, 5) the bearing is damaged, 6) the tightening force exerted by the bearing gland on the bearing is too large or too small, or the radial clearance is crushed, resulting in loss of flexibility.

105. What are the requirements for the performance of sliding bearing bushing materials?

Answer: 1) it shall have sufficient strength and plasticity. The bearing liner can not only bear certain working pressure, but also have uniform pressure distribution with the journal. 2) It has good foaming and wear resistance. 3) Good lubrication and heat dissipation performance. 4) Have good process performance.

106. What material should the shell of sliding bearing be made of?

Answer: cast steel, forged steel, cast iron

107. According to experience, what is the general radial clearance of bearing bush?

Answer: one thousandth to three thousandths of the shaft diameter can be taken according to different structural forms of bearings.

108. What is the effect of sliding bearing clearance?

A: 1) the clearance is small and the precision is high, but it is too small to ensure lubrication and form oil film. 2) Large clearance, low precision, easy to jump during operation and unstable oil film.

109. What are the items of bearing bush inspection?

Answer: 1) whether the position of the journal friction trace on the tungsten surface is correct, and the scraping and grinding patterns are polished or rubbed. 2) Whether the tungsten surface is scratched, damaged and corroded. 3) There are numerous cracks, local spalling and tire loss in tungsten gold (it can be tested by knocking with a wooden rod or oil immersion method). 4) Whether there is wear and corrosion on the bearing or spherical surface of the sizing block, whether the sizing block screw is loose and whether the sizing block is intact.

110. What are the advantages of tilting pad bearings?

A: the advantage of tilting pad is that each pad can swing freely, form the best oil film in any case, have good high-speed rotation stability and are not prone to oil film oscillation.

111. What kind of bearing position is unqualified?

Answer: 1) the original rotation accuracy is lost, 2) there is noise during operation, and 3) the rotation resistance is large.

112. What are the causes of overheating of centrifugal pump rolling bearing?

A: 1) the reserved axial clearance of rolling bearing is small, 2) the installation direction is incorrect, 3) dry wear or looseness, 4) the quality of lubricating oil is poor, the oil quantity is insufficient or the circulation is poor, 5) the oil slinger is deformed and can not carry oil.

113. What is the rejection standard for pump rolling bearings (radial ball bearings)?

Answer: 1) the inner and outer race raceways are peeling off, seriously worn or cracked. 2) The rolling element is out of round or the surface is peeled off with cracks. 3) The cage is severely worn or deformed, and the rolling element cannot be fixed. 4) There is noise or vibration when rotating, braking and reverse rotation when stopping. 5) The fit clearance of the bearing exceeds the maximum specified clearance.

114. What is the reason for the fish scale peeling on the track surface of the bearing inner ring and outer ring or the rolling surface of the rolling element?

Answer: 1) excessive load, 2) poor installation, 3) invasion of foreign matters, unsuitable lubricant, 4) unsuitable bearing clearance, 5) poor accuracy of shaft and bearing housing, uneven rigidity of bearing housing, large deflection of shaft, 6) rust, erosion points, scratches and indentation.

115. What are the properties of bearing alloys?

Answer: 1) low friction coefficient to reduce shaft wear; 2) High plasticity makes the shaft and bearing bush run in well; 3) Good thermal conductivity; 4) Sufficient compressive strength and fatigue strength.

116. What are the properties of sliding bearings that rotate at high speed?

Answer: 1) it shall be able to bear radial and axial loads; 2) Small friction coefficient is also required; 3) Long service life and stable and reliable operation under pressure.

117. What are the causes of rolling bearing vibration?

Answer: 1) random vibration transmitted by rolling element. 2) Random vibration occurs due to improper installation and lubrication. 3) Vibration from the outside of the bearing.

118. What are the assembly requirements for rolling bearings?

Answer: 1) the end face marked with model on the bearing shall be installed at the visible part for easy replacement. 2) The arc radius at the journal or shell hole shoulder shall be less than the arc chamfer radius of the bearing end face to ensure that the bearing is close to the shaft shoulder and shell hole shoulder after assembly. 3) The fixing device of the bearing must be intact and reliable, with moderate tightness and reliable relaxation. 4) During assembly, keep clean to prevent sundries from entering the bearing; 5) After assembly, the bearing rotates flexibly without noise, and the temperature rise generally does not exceed 50 degrees.

119. What are the bushing materials of common sliding bearings? What are the characteristics of each?

Answer: 1) gray cast iron is used under low speed, light load and no impact load. HT15-33 and HT20-40 are commonly used. 2) Copper base bearing alloy. Zqsn10-1 phosphor tin bronze and zqa19-4 aluminum bronze are commonly used, which are suitable for working under medium speed, high turbidity and impact load. 3) Oil bearing: it is generally a porous material made of bronze and cast iron powder pressed with an appropriate amount of graphite and sintered at high temperature. It is often used in low or medium speed, light load and inconvenient lubrication. 4) Nylon. Nylon 6, nylon 66 and nylon 1010 are commonly used. Nylon bearings have the advantages of good runnability, no damage to the journal after wear, good corrosion resistance, poor thermal conductivity and expansion after water absorption. 5) Bearing alloy (Babbitt). It is an alloy of tin, lead, copper and antimony. It has good wear resistance, but its strength is low. It can not be made into bearing bush alone. It is usually cast on the bearing bush matrix of bronze, cast iron and steel. 5) Three layer load bearing material. There are two commonly used materials: Polypropylene fluoroethylene steel body composite and polyoxymethylene steel body composite.

120. What is the reason for the excessive temperature rise of rolling bearing?

Answer: 1) impurities or dirt intrude during installation and operation. 2) Use improper lubricant or insufficient lubricating oil. 3) Friction is caused by friction or loose fit between sealing devices, hot rings, bushings, etc. 4) Incorrect installation, such as deflection of inner and outer rings, non concentricity of mounting seat holes, deformation of raceway and improper clearance adjustment. 5) If the type selection is wrong and the unsuitable bearing is selected for replacement, it will be heated due to overload or too high speed.

121. How to install the centripetal ball bearing on the shaft if the knock method is adopted?

Answer: use steel sleeve, copper sleeve or copper rod to knock the bearing ring symmetrically and evenly into the specified position. It is forbidden to knock the bearing outer ring to avoid damaging the bearing. After installation, check that the rotating bearing outer ring should be flexible and free from blocking.

122. What are the common disassembly methods of rolling bearings?

Answer: knock method, pull-out method, push method and hot disassembly method.

123. What should be paid attention to when disassembling the rolling bearing (the bearing is on the shaft) by knocking and pulling out?

Answer: 1) generally, the knocking force should act on the inner ring of the bearing, not on the rolling element and cage, and it is not allowed to knock on the outer ring of the bearing. 2) When using the pull-out method, the inner ring of the bearing should be pulled, not only the outer ring of the bearing, so as to avoid excessive loosening or damage of the bearing.

124. How to install the dial indicator when the sliding bearing adopts the shaft lifting method to measure the clearance?

Answer: after the bearing is installed, do not tighten the bolts. Set a dial indicator at the back of the upper bearing and at the shaft diameter. Gently lift the shaft without too high until the pointer of the dial indicator at the back of the upper bearing moves.

125. What are the assembly requirements for split radial sliding bearing, bearing cover and bearing seat?

Answer: during assembly, the back of the bearing bush shall be in good contact with the cover and seat hole, and the contact area shall not be less than 40% - 50% of the whole area, and it shall be evenly distributed without gap, otherwise it will need to be repaired and grinded. The end of the fixing pin and screw for fixing the sliding bearing shall be buried in the bearing body for 1-2mm. Various gaskets for air outlet and air outlet shall be in the same form as the tile surface, and their width shall be 1mm less than the inner side of the bearing. The gasket shall be flat without burrs, and the thickness of the gasket on both sides of the tile mouth shall be the same.

126. How to adjust the clearance of split radial sliding bearing?

Answer: 1) adjust the gasket at the joint surface to make the top clearance and side clearance of shaft and bearing bush meet the requirements. In the absence of regulations, one thousandth to two thousandths of the journal can be taken according to experience, which shall be selected according to the speed, load and lubrication. 2) The side clearance is generally half of the top clearance. 3) If the structure does not allow adding shims, the clearance shall be adjusted by grinding the pad mouth of the upper bearing bush. While repairing and grinding the clearance of the shoe mouth, ensure that the lower and upper shoe mouth shall fit closely, which shall not exceed 0.05mm.

127. What are the main forms of rolling bearing damage?

Answer: 1) fatigue pitting, 2) scratch, 3) burn, 4) electric corrosion, 5) cage damage, 6) inner and outer ring fracture, 7) ball out of round, 8) raceway surface peeling.

128. What are the characteristics of key connection?

Answer: relying on the side of the key to transmit torque, the parts on the shaft are only fixed in the circumferential direction and can not bear the axial force. If axial fixation is required, it is necessary to add positioning parts such as fastening screws or locating rings.

129. What are the assembly requirements for loose key connection?

Answer: for ordinary flat key, semicircular key and guide key, after assembly, it is required that there should be some interference on both sides of the key, a certain gap should be left on the top surface of the key, and the bottom surface of the key should be in contact with the bottom surface of the shaft groove. For the sliding key, the side key is in contact with the bottom surface of the wheel groove, and there is a gap between the key and the bottom surface of the shaft groove.

130. What are the preparation steps of loose key connection?

Answer: 1) clean the burrs on the keys and keyways. 2) The file shall be equipped with key length, and there shall be a gap of about 0.1mm between the key head and the shaft groove. 3) Try to match the key head with the keyway. For ordinary flat keys, flat round keys and guide keys, the key can only be embedded in the shaft groove, while the sliding key should be embedded in the wheel groove. 4) Add oil to the mating surface, and install the key on the shaft with a copper rod or a hammer cushion.

131. Precautions for installation and disassembly of ordinary flat key and shaft groove?

A: before installation, check and remove the burr and flash of the keyway, check the straightness of the key, leave a gap of 0.1mm between the key head and the keyway length, add oil on the mating surface and press the key into the keyway. Before disassembly, the key shall be gently knocked and loosened, and the key shall be lifted out from the end of the key head with a small flat shovel or screwdriver. It is strictly prohibited to hit or lift out from the matching side of the key.

132. What are the requirements for the fit between the key and the shaft?

Answer: 1) there shall be no problem on both sides of the key and keyway, and the top shall generally have a clearance of 0.1-0.4mm. 2) It is not allowed to increase the tightening force of the key by padding or twisting.

133. What are the four forms of coupling alignment analysis deviation?

Answer: concentric parallel, concentric non parallel, parallel non concentric, different hearts non parallel.

134. What is one point measurement?

A: the method of simultaneously measuring the axial and radial clearance at a certain position of the coupling at the same point is called one point method.

135. What is the principle of coupling alignment?

Answer: coupling alignment mainly measures its radial displacement and angular displacement. When the two shafts are in different axes, there is a relative deviation between the outer rings or end faces of the two couplings. The deviation value of the axis line can be calculated according to the measured deviation value. In order to obtain correct measurement results, the two rotors must rotate at the same angle to ensure that the relative position of the measuring point on the coupling is variable, In this way, the error caused by the non smooth surface of the coupling and the non vertical axis line of the end face can be eliminated.

136. What are the prerequisites for coupling centering?

Answer: 1) the axis of coupling and rotor coincide. 2) The outer diameters of journal and coupling are round. 3) The end face of the coupling is perpendicular to the axis. 4) Before centering the coupling, the runout of its radial and end face must be measured, and whether the runout of the journal meets the requirements.

137. What are the requirements for coupling assembly?

Answer: strictly ensure the coaxiality of the two axes, so that no unilateral load is generated during operation, so as to maintain balance and reduce vibration.

138. What are the methods for measuring radial displacement and angular displacement in the alignment of coupling?

Answer: 1) measure with support and feeler gauge. 2) Use the center card and feeler gauge to measure. 3) Use the center card and dial indicator to measure.

139. What is assembly? How many steps is the general assembly process?

A: in the production process, according to the drawings and technical requirements, the qualified parts are connected in various forms to form components, parts and finally form a complete machine, which is called assembly. The assembly process can generally be divided into component assembly, component assembly and final assembly.

140. How is assembly divided?

A: for some parts that need to be heated and have small matching parts, it is more appropriate to adopt cold installation due to the limitation of heating equipment. There are also some parts with special materials or parts with high accuracy requirements after assembly, and parts with very small deformation must be cold assembled.

141. How is assembly divided?

Answer: 1) assembly of components, 2) assembly of components; 3) General assembly, 4) general assembly and commissioning.

142. What are the assembly methods of interference connectors?

Answer: 1) press fitting method: this method can be divided into hammer method and press fitting method. 2) Thermal expansion matching method: it is the method of hot charging. It is often used for the assembly of interference connectors with the largest interference. 3) Cold shrink fitting method: the method of cold fitting is adopted. It is characterized by small shrinkage. It is generally used in interference fit occasions with small interference and limited by its method. 4) Hydraulic sleeve method: the hydraulic method is hole expansion. Interference fit for shaft shrink assembly.

143. What is the lead and pitch of a thread?

What do they have to do with them? A: lead: it is the distance that a point on the thread moves along the axis when it rotates around the helix. Pitch: it is the axial distance between the corresponding points of two adjacent teeth. Relationship: the lead of single head bolt is equal to the pitch, and the lead of multi head thread is equal to the product of the number of heads and the pitch.

144. Why should threaded connections be prevented from loosening?

What are the common ways to loosen the housing? A: generally, the threaded connection can meet the self-locking conditions and cannot fall off automatically, but when it is subject to vibration and impact load or large temperature change, the connection may be self loose. In order to connect reliably, anti loose shall be considered in the design. Methods: 1) friction locking. 2) Mechanical locking. 3) Other locking methods. Such as pins, nails, pads, caps, etc.

145. What are the four principles that should be followed when equipment accidents occur?

Answer: 1) don't let go until you find out the cause of the accident. 2) The person responsible for the accident and the masses were not spared by the Ministry of education. 3) There are no preventive measures. 4) If the responsible person is not punished, he will not let go.

146. What are the contents of "four understandings" and "three meetings" for operators?

Answer: 1) four understandings: understand equipment structure, equipment performance, equipment principle and equipment purpose. 2) Three skills: able to use, maintain and troubleshoot

147. What is the "five character" patrol inspection method for pumps?

A: "five character" patrol inspection method is to listen, touch, measure, see and smell.

148. What is the "cross" maintenance operation method of chemical centrifugal pump?

Answer: "cross" maintenance operation method is cleaning, sorting, lubrication, fastening and adjustment.