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Analysis of the common problems of rolling bearings and their causes
Source: Bearing network time: 2013-05-28
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.2) Bearing operation has a strange sound,
.3) bearing oscillations,
.4) the inner race is detached and cracked,
.5) The outer race is detached and cracked,
.6) bearing raceway and rollover indentation.
2. Analysis of the cause of the disease. 1) The device is not carefully viewed before the device; the bearing should be removed before the device and carefully look at the bearing seat, roll and cage; whether there are rust, burrs, bumps and cracks, check the bearing Whether the gap is suitable; whether the transformation can be light and self-sufficient; whether there is a sudden appearance, together with the scale, roundness and cylindricity of the shaft diameter and the bearing seat hole, and whether the appearance can be burred or uneven. Bearing housing; between the bearing surface of the bearing cap and the bearing base and the outer circular surface of the outer race; should leave a gap of 0. 1mm ~ 0. 25mm; to prevent the "bucket" on the two sides of the outer seat The appearance of the void caused by the reduction.
.2) The device is not properly installed. Inappropriate device will cause the bearing to exhibit the above-mentioned various faults; and the following situations:
A. The cooperation between the inner hole and the shaft of the bearing is selected by the base hole system; the cooperation between the outer circle of the bearing and the bearing housing hole is made by the base shaft system. Centrifugal pumps, centrifuges, reducers, motors and centrifugal type, which usually operate under normal load conditions. The shaft of the compressor and the inner race of the bearing; use j5; js5; js6; k5; k6; m6 cooperation; the bearing seat hole and the bearing outer race are selected j6; j7 cooperation. Rotating race (the inner race of most bearings) It is a rotating race; the outer race is not a rotating race; the other part is the opposite; usually the interference cooperation is used; it can prevent the race from rolling and sliding on the cooperation of the shaft diameter and the bearing seat hole under the load effect. .
However, sometimes the measurement of the shaft diameter and the bearing housing hole is inaccurate or the cooperation surface roughness does not reach the specification requirement; excessive interference cooperation is formed; the bearing race is greatly kneaded; then the radial direction of the bearing itself is incurred. The gap is cut; the bearing transformation is difficult and hot; the wear is aggravated or jammed; when the bearing is severe, the seat ring in the bearing case is cracked when installed. The non-rotating seat often uses the gap or the interference is not large; The circle has the ability to make small crawling; the contact surface of the race and the rolling body is constantly replaced; the raceway of the raceway is evenly worn. Together, the shaft can be eliminated due to thermal elongation and the rolling body in the bearing is axially stuck. The appearance, but the excessive gap cooperation; will cause the non-rotating seat to transform with the roll; causing severe wear of the shaft (or bearing seat hole) and the inner race (or outer race); ,oscillation.
B. If the device method is not suitable for the bearing and the shaft diameter or the interference of the bearing housing hole is small; the pressing method is often used. The simplest method is to use the copper rod and the hand hammer; the bearing is symmetrical symmetrically in a certain order. The seat; the bearing can be smoothly pressed into. Others; can also be used by soft metal casing by hand hammer or press press. If the operation is not proper, the seat will be deformed and cracked; On the seat of the interference cooperation; the raceway and the roll body will be indented or the bearing will be directly damaged.
C. When the temperature of the device is not properly controlled, the bearing is not properly rolled; if it has a large interference with the shaft diameter; the hot-packing device is usually used. The bearing is placed in the oil drum filled with organic oil; the outside of the oil drum is heated with hot water or flame. Heating; the process requires heating of the oil temperature at 80 ° C ~ 90 ° C; usually does not exceed 100 ° C; at most does not exceed 120 ° C. After the bearing is heated, the agile is taken out on the journal. If the temperature is not properly controlled, the heating temperature is over. High; it will cause the bearing to temper and cause the hardness to decrease; the bearing will be easy to wear, fall off, or even crack in the operation.
D. When the device is not properly adjusted, the gap of the rolling bearing is divided into radial clearance and axial clearance; its function is to ensure the normal operation and smoothness of the rolling body and to compensate for the thermal elongation.
Regarding the gap-adjustable bearing; because of the proportional relationship between the axial clearance and the radial clearance; the device only needs to adjust the axial clearance to achieve the required radial clearance; It is used in pairs (that is, at the two ends or one end of the shaft); therefore; only need to adjust the axial clearance of a bearing. Usually the gasket is used to adjust the axial clearance; some can also be adjusted with screws or thrust rings. .
Rolling bearings with no adjustment of the gap; since the radial clearance is determined according to the specifications at the time of manufacture; adjustment cannot be made; such bearings are mounted on the shaft diameter or in the bore of the bearing housing; the practical radial clearance is called Radial clearance of the device; the device should make the radial gap of the device just enough to form the necessary radial gap in the operation; to ensure the sensitive transformation of the bearing. This kind of bearing is in operation; because the shaft is heated and extended when the temperature rises Long so that the inner seat is relatively displaced; then the radial clearance of the bearing is reduced; even the roll is caught between the races. If one of the double-bearing roll bearings is fixed (the other bearing is fixed at Axial clearance is left between the shaft and the bearing housing) and the side cover; this can be prevented.
It can be seen from the above that the rolling bearing can be adjusted regardless of the gap or the gap is not adjusted; they need to adjust the axial gap when the device is installed (but some bearings whose gap is not adjusted need not leave the axial gap); Thermal elongation; then ensure the normal operation of the tumbler. If the axial clearance is too small; the bearing transformation will be difficult and hot; even if the rolling body is stuck or broken, if the axial clearance is too large, it will lead to the occurrence of the operation. A strange sound; or even a severe oscillation or damage to the cage.
E. The coupling is not properly aligned. The input shaft of most working equipment is connected to the power shaft through the coupling; therefore, it is necessary to perform the alignment of the coupling when the device is installed; the driving shaft and the driven shaft are on the same axis.
.3) Smooth oil (or smooth grease) used in smooth poor rolling bearings has a certain operating temperature; when the temperature is too high, it will change; then the smoothing effect is lost; the bearing is burnt due to high temperature. Other; smooth oil (or smooth grease) poor texture or oiling (fat) in operation is not timely; it will also form bearing temperature rise or abnormal sound.
.4) Rotor imbalance Generally speaking, the rotor of the working equipment must be moved and statically balanced before the device; therefore, the bearing will not present a problem. However, some rotors are subject to corrosion or solids during the operation. Wear of impurities; perhaps the axis is tortuous; it will cause unbalanced centrifugal force; then the bearing will heat up and oscillate; the raceway will be severely worn; until it is damaged.
.5) Check if the replacement is not in time for the bearing operation; check according to the rules; if there is fever, abnormal sound, oscillation, etc.; timely parking to find the reason; eliminate the problem; if the bearing finds severe fatigue, oxidative corrosion, Worn pits, cracks, hardness drop to HRC <60; or when excessive noise can not be adjusted; should be replaced in time. If the inspection and replacement are not timely; it will form severe damage to the bearing and even the rotor; then affect the normal production. Others; the bearing is not properly disassembled, the oscillation of the equipment anchor bolts is loose; it will also cause the bearing raceway and the rolling body to indent the indentation; the crack of the inner and outer races of the bearing.
3. Ways to eliminate the problem. 1) When replacing the bearing; look carefully at the new bearing; take a detailed look at the shaft diameter and the housing bore and rotor,
.2) When installing the device and disassembling the bearing; strictly perform the inspection and repair process; carefully operate; prevent the bearing damage caused by improper assembly and disassembly,
.3) on time and oil change; to ensure that the bearing operation has been in an outstanding situation,
.4) Look carefully during the operation; find the risk of illness; eliminate it in time.
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