The bearing of limestone crusher has the problem of long-term heating, and two sets of bearings need to be changed every year, which not only affects the increase of expenditure, but also affects the production efficiency. The clearance problem leads to the treatment measures of heating of the bearing of crusher
1. Basic information of crusher
In the production process, the temperature of the two sets of bearing of the crusher rotor is around 85℃ all year round. Especially in summer, the bearing must be cooled down with compressed air, or even cooled by cooling water on the bearing seat at the end of the pulley, so as to maintain normal production.Crusher free end (non-transmission end) bearing due to heat damage, every year to replace two sets.
2. Analysis of bearing heating
(1) selection of lubricating oil:
The rotor bearing of the crusher is lubricated by mobil EP2 grease. The various indexes of grease can meet the stable operation of the bearing.
(2) problems of lubricating oil pollution:
Open the end cover of the bearing and check, the grease is clean and no impurities such as ash are introduced, so as to eliminate the bearing heat caused by this problem.
(3) excessive addition of grease in the bearing:
In general, excessive grease will lead to poor bearing heat dissipation, resulting in bearing heat.There is an oil drain hole at the lower end of the end cover of each bearing seat of the crusher rotor. Excessive oil addition will lead to a rise in temperature in a short time. After the old oil is discharged after a period of operation, the temperature of the bearing will return to normal.The crusher bearing perennial temperature in 85℃ or so high temperature operation, it should not be caused by this.
(4) bearing assembly:
Open the outer end cover of the free end bearing for inspection, measure the distance from the outer ring of the bearing to the side of the bearing seat is 26.3mm, and measure the length of the end cover stop of the bearing 30mm.
(5) calculation of thermal expansion of rotor shaft:
The center distance between the two ends of the bearing is 3400mm, the working temperature difference is 100℃, the expansion coefficient of ordinary carbon steel is 1.2×10-5/℃;The expansion amount was 4.08mm(3400mm×100℃×1.2×10-5/℃).
Compared with the two data, the problem of bearing heating was confirmed. It was because the outer end cover of the free end bearing was pressed too tightly, the end cover stop was pressed on the outer ring of the bearing, and there was no thermal expansion of the rotor shaft, which caused the bearing heating of the crusher.
When the limestone crusher works normally, the thermal expansion of the rotor shaft is 4.08mm.When the rotor is running, the bearing temperature will gradually rise, the rotor shaft will also elongate, and the free end bearing will produce axial displacement with the change of temperature.In consideration of assembly size and other errors, during the installation process of the rotor, a distance of more than 10mm should be reserved between the outer end cap and the outer ring of the free end bearing to ensure the thermal expansion of the rotor shaft in the normal production process. Otherwise, the bearing will suffer from high temperature due to the axial force and run for a long time, and the bearing will be damaged.
Therefore, the problem of swimming clearance is the root cause of bearing running at high temperature for a long time.
3. Measures to solve the heat of crusher bearing
According to the above analysis, the non-axial thermal expansion of free-end bearing is the main cause of bearing heating, which can be solved by adjusting the gap between the outer ring of bearing and the stop of bearing end cap.
There are two solutions, one is the bearing end cover stop car off 10mm;The other is to add a gasket to move the bearing end cover out.
After proper installation of the limestone crusher, the working temperature of the free end bearing is stable at 56℃ and the temperature of the belt wheel end bearing is stable at 68℃ after starting production, and the bearing heating problem is completely solved.The abnormal situation of the equipment is mostly caused by the incorrect installation according to the technical specification.As long as the cause is found and targeted technical measures are taken, the problem will be readily solved.
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