Discuss the influence of bearing matching on operation

The matching of the bearing load and the motor is a problem that must be taken into account in the design of the motor. Reasonable bearing selection will effectively avoid some unnecessary troubles.

Ms. Sen's friends encountered one thing. Their motors were noisy during no-load operation, but the load was running smoothly and quietly. Communication with the bearing manufacturers revealed that their selection of motor bearings was unreasonable. The load capacity is recalculated.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

How to calculate bearing dynamic load

The load acting on the bearing can be calculated according to the mechanics principle under known or calculable external forces (such as the transmission force and the working force on inertial force).

When calculating the force component of a single bearing load, the shaft is considered to be a beam supported by a rigid and torque-free fulcrum in order to simplify the calculation. Elastic deformation of bearings, housings, or mechanical structures. Shaft deflection results in moments acting on the bearings, all without regard to simplified calculations.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Applying the above simplified theory, only a very simple auxiliary tool, such as a small calculator, can be used for calculation. In fact, the standard method for calculating basic load ratings and equivalent bearing loads is based on similar assumptions.

Using advanced and complex calculation procedures, the bearing load can be calculated based on the elasticity theory without using the above assumptions. In these calculation procedures, bearings, shafts, and housings are all considered as elastic parts of the system.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

External forces include the inherent weight of the shaft and the components it carries, or the weight of the vehicle and other inertia forces. These are generally known or can be calculated.

However, other external forces, such as work force (rolling force and cutting force of the machine tool, etc.), impact force and additional dynamic force (such as centrifugal force due to imbalance), usually depend on the experience of a similar machine or pumping configuration to determine. .

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

● Gear transmission

For gear transmission, the theoretically generated force of the gear can be calculated from the transmission power and the type of gear. However, there are other dynamic forces generated by gears, transmission ends or outputs.

In addition, the shape error of the gear and the imbalance of the rotating parts also cause additional dynamic forces. However, gears are generally manufactured with very high precision standards to reduce noise during operation, so the force generated by this reason is usually very small and can be neglected when calculating the bearing load.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Machines using gear transmissions can only determine the additional forces generated according to their mode of operation and mode if the operating conditions are known. Depending on the operating conditions, gear manufacturers can usually provide a “work” factor for impact load and gear efficiency. This coefficient can be used to consider the effect of additional forces on bearing life rating.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

● Belt drive

When calculating the belt drive bearing load, the most important consideration is the effective belt torque, which depends on the transmitted torque. Belt manufacturers generally provide a system for calculating the belt tension based on the type of belt that is not being asked, the preload, the tension of the belt, and other additional dynamic forces.

If you cannot get the relevant coefficients, use the following reference values:

Belt with teeth - 1.1 to 1.3;

Triangle belt (V-shaped belt) - 1.2 to 2.5;

Flat belt - 1.5 to 4.5;

When the distance between the shafts is short, under heavy load or impact load, or when the tension is large, larger values should be taken.

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Discuss the influence of bearing matching on operation failure of permanent magnet motor

Bearing static and dynamic loads

The bearing load capacity at rest is determined by the amount of plastic deformation allowed. Plastic deformation in rolling bearings is unavoidable. If the allowable plastic deformation limit is small, the bearing static load capacity is also small;

If the allowable plastic deformation is large, the pits generated on the raceway will cause the noise and vibration of the bearing during operation to increase, the running accuracy to decrease, and affect the normal operation of the bearing.

Discuss the influence of bearing matching on operation failure of permanent magnet motor