Through measurement, if it is found that the operating temperature of the rolling bearing
exceeds the allowable value (such as 95°C) or rises faster, other means and analysis should be used to find out the cause and solve it.
Take the motor as an example to introduce the reasons for the high temperature.
1) The quality of the bearing is poor or it has been damaged during transportation and handling before operation. During the transportation, the road is bumpy, and the rotor jumps up and down to drive the bearing roller to impact the outer ring raceway of the bearing. With this kind of damage, a rhythmic "just, just" sound can be heard from the bearing when the motor is running.
2) The coaxiality of the bearing and the shaft or the bearing chamber does not meet the requirements
3) The outer ring of the bearing at one end that should be able to move axially is crushed to death by the bearing cap. When the running shaft is elongated due to temperature rise, it drives the inner ring of the bearing away from the original axial position, thereby squeezing the ball grinding side raceway and generating more heat.
4) The tight fit between the bearing and the rotating shaft or the bearing chamber will cause the inner ring or outer ring of the bearing to be squeezed and deformed, the radial clearance will become smaller, the rolling will be difficult, and more heat will be generated.
5) The bearing is too loose with the shaft or the bearing chamber, so that the inner ring of the bearing slides quickly on the shaft and the outer ring in the bearing chamber (sliding of the inner ring is absolutely not allowed, and very slow sliding of the outer ring is impossible in many cases) Harmful). This kind of friction will generate a lot of heat, which will cause the temperature to rise sharply. In severe cases, the bearing will be damaged in a short time, and then the stator and rotor will rub against each other, and the winding will burn out due to overcurrent.
6) Too much grease, too little or deteriorated. For the bearing chamber structure with an oil retaining plate, if the grease is not replenished in time, the phenomenon of too little grease will gradually appear. In addition, the use of high-temperature resistant grease at low temperature will generate relatively more heat due to its high temperature.
7) Dust in the environment enters the bearing through the gap between the bearing cover and the rotating shaft, which can greatly reduce the lubrication function of the grease, increase frictional resistance, and generate more heat.
8) The rotor is overheated due to various reasons, and the heat of the rotor is transferred to the bearing, so that the temperature of the lubricating grease in the bearing reaches its dropping point and becomes liquid and lost, and the bearing loses lubrication and generates high heat