Technical Causes of Screw Pump Sleeve and Axle Diameter Locking

Through the screw pump sleeve locking analysis of the media and the speed of the sleeve clearance requirements. Proposed to solve the sleeve locking the rectification program. Proved by practice, after transformation of the equipment operating parameters are all normal.

Keywords: screw pump sleeve bearing life gap

I. Introduction

My company suddenly a screw pump trip. Maintenance staff rush to the scene to investigate the cause of the pump and maintenance. After the demolition of the pump inspection, the reason for the tripping of copper shaft sleeve and shaft lock. Now combined with the shaft sleeve clearance to lock it about the technical description.

Second, the reason analysis

According to the working condition of the sliding bearing, the bushing hole and the shaft are matched with the clearance fit. The size deviation between the shaft diameter and the bushing aperture diameter of the parts is generally ensured by the average working temperature of 20 DEG C Change determined. Affect the sliding bearing overheating failure of many factors in the bearing structure design is reasonable, the material used in the right circumstances, the main bearing overheating is the radial clearance size of the improper assembly and improper use caused.

Radial clearance of sliding bearing bearing overheating failure, the radial clearance of the sliding bearing Δ is the difference between the diameter of the bearing hole and the journal diameter, the sliding bearing to leave a certain radial clearance, its role is as follows: Is to achieve shaft and bearing Activities at least the conditions of the joint; is to ensure the operation of the shaft accuracy assurance; is the formation of an important condition for liquid lubrication. Therefore, the radial clearance of plain bearings is very important, too large or too small are extremely harmful. The gap is too small, it is difficult to form a lubricating oil film, the friction heat is not easy to be taken away, the bearing overheating, serious "will hold the shaft"; gap is too large, the oil film is difficult to form, will reduce the machine running accuracy, will produce severe vibration and noise , And even lead to tile accidents.

Third, determine the radial clearance of the sliding bearing

Technical performance of the screw pump: journal speed n = 2950r / min, journal diameter d = 30mm; motor for synchronous motor, oil residue, bearing material is tin-based copper.

Theoretical Radial Clearance of Plain Bearings Radial Clearance of Slewing Bearing Δ = K · d.

Where: K --- high-precision bearing factor, from the "Mechanical Design Manual" found K = 0.0008.

d --- journal diameter, d = 30mm.

Substitute: Δ = 0.02mm

Investigated by "Mechanical Design Manual", the maximum clearance Δmax = 0.10mm.

Measurement of the original bushing, data and location:

Shaft diameter measurement, the corresponding position size data:

Shaft diameter 1: 29.99mm29.94mm29.90mm

Shaft diameter 2: 29.92mm29.90mm29.90mm

Sleeve 1: 30.01mm29.97mm29.92mm

Bushing 2: 29.94mm29.92mm29.915mm

The actual value of the radial clearance of the sliding bearing Maximum clearance: Active rod: 0.03mm Follower rod: 0.02mm.

The bearing in the actual use of the process, due to the gap is too small, friction heat is not easy to be taken away, combined with oil as the media residue, more impurities, easy to enter the gap, the bearing overheating, serious "will be" axle " Watt phenomenon.

Fourth, prevention and improvement measures

In order to prevent bearing overheating failure, if the radial gap larger, Δ = 0.03mm. At this time the bearing with the vice although the normal work, but its service life is greatly reduced, so in determining the radial bearing clearance, should ensure that the bearing under the premise of normal work to stay as small as possible. After the bearing assembly, the first grinding should try to run the good run-in specifications and test run, and then gradually load acceleration, the shaft and bearing surface with raised convex, and finally put into normal operation. Otherwise, even if the clearance is not too small, but because after the assembly without trial run, and put into normal operation, resulting in bearing overheating or even burning tile. In this regard, the radial clearance of the sliding bearing should be controlled at 0.10mm ~ 0.15mm.

Radial clearance of bearing overheating and bearing life is greatly affected, so for the radial clearance, we must strictly control within a reasonable range. In determining the bearing radial clearance, to fully consider the factors that affect the radial clearance, in addition to considering the shaft diameter, speed, load and machine accuracy, but also consider the following points:

a. bearing material. Different bearing materials, different expansion coefficient, the gap is different.

b. Shaft and bearing surface roughness.

c. journal and bearing geometry and mutual position error (ie, roundness, cylindricity, coaxiality, etc.).

d. bearing operating temperature.

f. sudden changes in starting conditions.

Fifth, the conclusion

Different media and different speeds of the screw pump shaft clearance requirements are not the same. Through the above calculation and analysis, the best clearance data of the sleeve was obtained. Equipment to transform the normal operation of a year to verify that our analysis is feasible.