How to select and use the bearings?

Bearings are mainly used to support and reduce friction in machinery, so the precision and noise of bearing are directly related to the use and life of machinery.

1.Bearing selection

1).Bearing type selection: bearing model is generally based on the use condition of the supporting products and the bearing under the load bearing.

2).Bearing clearance selection: the use condition, speed, temperature and tolerance of the bearing are directly related to the selection of bearing clearance. Generally, the motor of the speed of 3, 500 RPM is adopted in the CM clearance, such as high temperature high speed motor requires relatively large clearance. The bearing clearance will be reduced due to the increase of the inner hole and the reduction of the outer circle. The decrease of the clearance is = over 60% (except for aluminum). For example, the front clearance of the bearing assembly is 0.01 mm, the volume of the assembly is 0.01 mm, and the clearance of the bearing after assembly is 0.004 mm. In theory, the noise and life of the bearing can reach the optimal state during the zero clearance, but in the actual operation, the temperature rise and other problems are considered, and the clearance of the bearing after assembly is 0.002 mm - 0.004 mm.

3).Grease selection: the choice of oil is generally based on the bearing speed, high temperature resistance, noise requirement and starting torque.

4).Bearing seal selection: the lubrication of the bearing can be divided into oil lubrication and grease lubrication. Oil lubricated bearings are generally used in the form of bearings, grease lubricated bearings are usually sealed with dust cover or rubber seals. Dust cover suitable for high temperature or the use of good parts, seal two points contact seal and non-contact seal and contact seal dustproof performance is good but the starting torque, non-contact seal starting torque is small, but there is no contact sealing performance is good.

2.Bearing usage note

1).The selection and control of shaft and bearing tolerances: the bearing should rotate flexibly without block after bearing pressure. If the apparent rotation is not flexible, the bearing is too big, the tolerance should be lowered. If the bearing is pressed into the shaft, the movement of the hand is obviously "sand and sand". It may be that the tolerance of the shaft is too large or the axis is not good, so it is important to control the roundness in the control of the shaft and the bearing tolerance.

2).Bearing assembly method: because the bearing is a high precision product, if the improper assembly can easily cause damage to the bearing channel, the bearing is damaged. The bearing should be used in the assembly of the special mold, cannot be knocked at will, when pressing the shaft, can only small circle force, the large circle can only bear the force when the big circle. When assembling, use air pressure or hydraulic pressure, and the upper and lower mould should be outside the horizontal state when pressing, such as inclined can cause the bearing channel to be damaged by force, and the bearing will produce the lead.

3).The prevention of assembly foreign body: the bearing is easy to enter the dynamic balance when it is put into the rotor to make the dynamic balance, so it is better to have the dynamic balance before bearing the bearing. It's best not to grease or grease the bearings.

4).Paint the rust prevention: paint rust is characterized by multiple in sealed type motor, the motor sound is very good, when it is assembled but put some time in the warehouse, the motor sound is very big, remove the bearing has serious rust phenomenon. The problem is mainly the corrosive material formed by the volatile acid of the insulating paint at certain temperature and humidity.