Angular contact ball bearing preloading method and determination method.

Because there is clearance in angular contact ball bearings, the inner and outer rings will move relative to each other under load, which will reduce the rigidity of the bearing. In order to reduce vibration, preloading is often used when installing angular contact ball bearings to eliminate the original load. clearance.

Method of preloading angular contact ball bearings

The preloading methods of angular contact ball bearings include radial preloading and axial preloading.

1. Radial preload

Radial preloading is usually achieved by expanding the inner ring of the bearing, or by moving the axial position of the inner tapered hole of the bearing to achieve preloading.

2. Axial preload

Commonly used axial preloading methods include grinding washer thickness, adjusting inner and outer spacer thickness, spring preloading, narrowing inner and outer rings, screw cover adjustment, and thrust ring adjustment.

(1) Method of adjusting the thickness of inner and outer spacers

Preloading is achieved by adjusting the thickness of the inner and outer spacers. Due to the thickness of the spacers, a preload force is generated between the inner and outer rings of the angular contact ball bearing.

(2) Grinding washer thickness method

The inner and outer rings of the bearing are relatively moved to achieve preloading. When the thickness of washer 1 is smaller, the preloading force of the angular contact ball bearing is greater; when the thickness of washer 2 is smaller, the preloading force is smaller.

(3) Narrowing the inner and outer rings

Preloading is achieved by grinding the inner or outer rings of bearings used in pairs. To narrow the inner ring, the two inner rings are pressed relatively tightly during assembly, and the bearing can produce preload; to grind the outer ring to narrow the assembly, When the two outer rings are relatively compressed, the bearing can be preloaded.

(4)Spring preloading method

Preloading is achieved with springs, which can compensate for bearing wear and the effects of axial thermal expansion at any time, while the preloading force remains basically unchanged

(5)Thrust ring adjustment method

First tighten the thrust ring with external threads until it becomes tight when the shaft rotates. Then screw the thrust ring to a certain angle according to the axial clearance requirements, and then pre-fix it with a stopper.

(6) Screw cover adjustment method

When adjusting, first screw the adjusting screw forward so that the cover is close to the end face of the bearing outer ring until it becomes tight when the shaft rotates. Then screw the adjusting screw back a few clicks until the axial clearance of the bearing is appropriate. After adjustment, , tighten the locking nut, and then check the clearance. The above process can be repeated several times until the bearing is adjusted to the appropriate state.

Determination of preload of angular contact ball bearings

The axial preload of angular contact ball bearings is achieved by relative movement between the inner and outer rings. The amount of relative movement between the inner and outer rings is determined by the preload value. For this reason, when the preload has been determined, the measurement method can be used to measure the relative movement of the inner and outer rings, so that the values required for adding washers or narrowing the bearing can be obtained, and the relative movement of the inner and outer rings of the angular contact ball bearing can be determined. The methods are as follows:

1.Measurement method

Place the angular contact ball bearing on the circular seat body and add weight (i.e. preload amount). Under the action of pressure, the bearing eliminates the clearance and causes certain elastic deformation of the balls and raceways. Use a liver gauge to measure the height difference between the inner and outer rings at both ends of the bearing, and (measure every 120 times, take the average value), you can get the thickness value of the washer that should be added to the bearing end face before assembly, or the bearing end face that should be ground narrow. magnitude.

2. Calculation method

For structures without spacers between the two bearings, the relative axial movement of the inner and outer rings of the bearings can also be used to reflect the preload. When the designer provides parameters, the preload needs to be calculated. If the design is based on the bearings in the machine, Working external force, propose the amount of preload that should be added to the selected bearing, and mark this parameter in the product manual or assembly drawing, so that the assembler can use the measurement method to measure the axial direction of the inner and outer rings of the bearing when preloading the bearing. Relative movement amount.

3. Feeling method

This method does not require any measuring instruments and equipment, and only relies on the practical experience of the mechanic to determine the thickness difference between the inner and outer spacers. Because this method can obtain a more accurate preload amount, the temperature rise of the bearing is low during operation, and the service life is long, so it is widely used. There are three commonly used sensory methods:

(1) Fill the inner and outer spacers of the two paired bearings according to the installation method. In advance, drill three φ2 ~ qp3mm small holes on the outer circle of the outer spacer ring at 120° intervals, and press the upper part of the inner ring of the bearing. With a weight equal to the preload, use a small rod with a diameter equal to or less than φ1.5mm to touch the inner spacer through three small holes in sequence. Check the resistance of the inner and outer spacers between the two bearing end faces. It is required to feel the inner and outer spacers with your hands. The resistance of the circle is similar. If the resistance is different, you can grind the end face of the insulation to meet the requirements.

(2) Use the two fingers of your left hand to eliminate all the clearance of the two bearings and tighten them (generally equivalent to a preload of about 50N), and use the fingers of your right hand to move the inner and outer spacers respectively to check whether their resistances are similar. If the resistance is different, the end face of the spacer can be ground to the requirements.

(3) Use the thumb and index finger of both hands to eliminate all the clearance of the two bearings, and insert one middle finger into the inner hole of the bearing to move the inner spacer ring that was originally placed, and check whether its resistance is similar to that of the outer spacer ring. Measuring using the sensory method requires the mechanic to have sufficient practical experience. If the experience is insufficient, it is better to use the calculation method or the measurement method.

The above introduces the preloading method and measurement of angular contact ball bearings. By preloading angular contact ball bearings, the rigidity of the bearings and their service life are improved.