How to assemble rolling bearings, assembly steps and precautions of rolling bearings

1) Press-in method.

When the inner bore of the bearing fits tightly with the journal and the outer ring fits loosely with the housing, the bearing should be installed on the shaft first, as shown in Figure 9-33a; Otherwise, the bearing should be pressed into the housing first, as shown in Figure 9-33b. If the inner bore of the bearing fits tightly with the journal, and the outer ring fits tightly with the housing, the inner bore and the outer ring of the bearing should be installed on the shaft and the housing at the same time, as shown in Figure 9-33c.

Figure 9-33 Assembling a rolling bearing by press-fit method.

2) Uniform knock-in method.

When the interference amount is small and there is no special sleeve, the round bar can be evenly knocked into the inner ring (or outer ring) of the bearing, as shown in Figure 9-34. It can also be hammered in by assembling the matching cylinder, as shown in Figure 9-35. However, soft metals such as copper rods cannot be used, because it is easy to fall soft metal chips into the bearing, and the bearing cannot be directly hit with a hammer.

When striking, it should be tapped symmetrically and evenly around to avoid tilting the bearing due to excessive force or concentrated knocking.

Figure 9-34 Assembling a rolling bearing using the uniform knock-in method.

Figure 9-35 Assembling a rolling bearing with a hammer and a matching cylinder.

3) Machine pressure method.

Figure 9-36 Press-fitting a rolling bearing with a lever rack or screw press.

4) Hydraulic sleeve method.

This method is suitable for large bearing size and interference and requires frequent disassembly, and can also be used for precision bearings that cannot be hammered. When assembling the taper bore bearing, the high-pressure oil generated by the hand pump enters the shaft end, is introduced into the annular groove of the journal through the path, so that the inner bore of the bearing is expanded, and then the shaft nut is tightened to load the bearing, as shown in Figure 9-37.

Figure 9-37 Assembling a taper bore bearing using the hydraulic sleeve method.

5) Temperature difference method.

Bearings with an interference fit are often assembled using the temperature difference method. The bearing can be heated in the oil pool of 80 100, and should be placed on the grid at a certain height from the bottom of the oil pool (Fig. 9-38a), and the smaller bearing can be heated by hanging the hook in the oil pool (Fig. 9-38b) to prevent overheating.

Figure 9-38 Oil pool heating method.

After taking out the bearing, measure the bearing bore diameter with a measuring rod that is about larger than the size of the journal, if the size is suitable, immediately wipe the oil stains and attachments with a clean cloth, and use a cloth to pad the bearing and flatten, quickly push the bearing into the journal, assemble it with the shaft diameter while it is hot, always push the bearing by hand during the cooling process, and slightly rotate the outer ring to prevent tilting or jamming (Figure 9-38c), and a firm fit will be produced after cooling. If you want to remove the bearing, you have to put it in oil and warm it. It can also be placed in an industrial refrigerator to cool the bearings or parts, or placed in a sealed box with a lid, poured dry ice or liquid nitrogen, kept warm for a period of time, and then taken out for assembly.

It is best to heat the assembly in hot oil at 100 degrees.

Answer]: Before assembly: clean the bearing and bearing parts with gasoline or kerosene, coat the surface with lubricating oil (grease), measure the size of the shaft and the seat hole, and avoid over-tight loading.

When assembling: it must be ensured that the rolling elements are not under pressure and the mating surface is not scratched. When pressing the bearing with a hand hammer, in order to make the bearing evenly stressed, it is necessary to press on the bearing housing ring with a copper rod or a mild steel sleeve pad, and the bearing cannot be directly hit with a hand hammer.

a.When the amount of fitting interference is large, the bearing assembly can be put on the collar and mechanically pressed in by the pressure method. b.

When the interference amount is too large, the heat sleeve method can be used for assembly, and the temperature shall not exceed +100. c.When the bearing is pressed against the journal, a force is applied to the end face of the inner ring.

d.When the bearing is pressed into the housing bore, a force is applied to the end face of the outer ring. e.

When the bearing is pressed into the journal or the housing hole at the same time, the force should be applied to the inner and outer ring end faces at the same time After assembly: the bearing operation should be flexible, noiseless, and the working temperature should not exceed 70.

Technical requirements for assembly:

1. The end face of the rolling bearing marked with the code should be installed in the visible direction, so that it can be checked when replaced;

2. The arc radius at the shaft journal or shell hole step should be less than the arc radius crack at the corresponding place on the bearing;

3. After the bearing is assembled on the shaft and in the shell hole, there should be no skewness;

4. In the two bearings of the same car sensitive shaft, one of the shafts must move with the shaft when it expands;

5. When assembling rolling bearings, dirt must be strictly prevented from entering the bearings;

6. The assembled bearing must operate flexibly, with low noise, and the working temperature should generally not exceed 65 degrees Celsius.

Mounting of rolling bearings - several mounting methods for bearings.

1) Installation of radial thrust bearings.

Radial thrust bearings include tapered roller bearings and angular contact ball bearings, they are usually installed in pairs, most of these bearings are separable, so the installation operation is generally very convenient, just pay attention to the adjustment of its clearance during installation, and the bearing clearance is crucial to the service life and working characteristics of this type of bearing, and the specific adjustment method is shown in the relevant part. The internal clearance of non-separable radial thrust bearings is generally pre-set.

2) Thrust bearing installation.

Thrust bearings generally take the shaft ring and shaft as the transition fit, and take the housing ring and the bearing housing hole as the dynamic fit, so this kind of bearing is easy to install.

When this kind of bearing is installed, it is necessary to control the verticality of the shaft axis of the shaft raceway (or groove bottom), if the verticality is out of control, the load on the bearing will be biased to one side and prone to early failure, and the running performance will also be greatly affected.

If this kind of bearing is to bear one-way load, most of them are installed in pairs, but only bear the load in one direction when running, so it is necessary to give a certain preload force to prevent the bearing that does not bear the load from being too loose, and the rolling elements slip on the raceway and wear violently.

For the rolling elements in the bidirectional thrust bearings that do not bear the load, a similar method should be used to preload them to prevent similar severe wear.

3) Installation of needle roller bearings.

Needle roller bearings with cages are mounted in a similar way to radial bearings, but require more care, because the rings of needle roller bearings are generally thin, brittle and easy to break, or weak and easy to deform.

Some needle roller bearings without cages are easy to scatter needle rollers, and in this case, the following method can be used to install: the scattered needle roller surface is coated with grease, and then these needle rollers are tightly adhered to the ferrule (needle roller sleeve) of the needle roller one by one, pay attention not to scratch the needle roller surface or raceway surface when inserting, and the number of needle rollers inserted is consistent with the number of needle rollers in the original set of bearings.

In the actual installation, can also be combined with the specific situation, design a special tool for installing the bearing, or utilize the thread, bolt hole etc. on the shaft or bearing seat of the mounting part, make the installation work of the bearing easier and faster.

a. Press-fit fit.

When the inner ring of the bearing is tightly matched with the shaft, and the outer ring is loosely matched with the housing bore, the bearing can be pressed on the shaft with a press, and then the shaft is loaded into the housing bore together with the bearing. When press-fitting, on the end face of the inner ring of the bearing, a soft metal material is padded with the matching pipe "copper or mild steel". The inner diameter of the fitting tube should be slightly larger than the journal diameter, and the outer diameter diameter should be slightly smaller than the bearing inner ring flange, so as not to press on the cage.

When the outer ring of the bearing is tightly fit with the housing bore, and when the inner ring and the shaft are loosely fitted, the bearing can be pressed into the housing bore first, and the outer diameter of the matching pipe should be slightly smaller than the diameter of the housing bore.

If the bearing ring is tightly fitted with the shaft and the housing hole, the inner ring and the outer ring should be pressed into the shaft and the housing hole at the same time during installation, and the structure of the matching pipe should be able to compress the end face of the inner ring and the outer ring of the bearing at the same time.

b. Heating fit.

This is a mounting method that uses thermal expansion to convert a tight fit into a loose fit by heating the bearing or housing. It is a common and labor-saving installation method. This method is suitable for the installation of bearings with large interference.

Before hot installation, put the ring of bearing or separable bearing into the oil tank to heat 80 100 evenly, and then take out the oil and install it on the shaft as soon as possible, in order to prevent the end face of the inner ring and the shoulder of the shaft from fitting tightly after cooling, the bearing can be axial fastening after cooling. When the outer ring of the bearing is tightly fitted with a light metal bearing, the hot fitting method of heating the bearing seat is used to prevent abrasion on the mating surface.

When heating the bearing with the oil tank, apply a grid (as shown in Figure 2-7) at a certain distance from the bottom of the box, or hang the bearing with a hook, the bearing can not be put on the bottom of the box, in order to prevent the precipitation of impurities from entering the bearing or uneven heating, there must be a thermometer in the oil tank, and the oil temperature shall not exceed 100 to prevent the return effect and reduce the hardness of the ring.

c. Installation of tapered bore bearings.

Tapered bore bearings can be mounted directly on taper journals or on the taper of adapter and withdrawal sleeves, and the degree of tightness of the fit can be measured by the reduction of the radial clearance of the bearing. Therefore, the radial clearance of the bearing should be measured before installation, and the clearance should be measured frequently during the installation process to achieve the required clearance reduction. The installation is generally installed with a lock nut, and the method of heated installation can also be used.

d. Installation of thrust bearings.

The fit between the shaft ring of the thrust bearing and the shaft is generally a transitional fit, and the fit between the seat ring and the bearing housing hole is generally a clearance fit, so this kind of bearing is easier to install, and the central shaft ring of the bidirectional thrust bearing should be fixed on the shaft to prevent rotation relative to the shaft.

The inner ring is warm-sleeved, and the outer ring is generally mounted with the bearing shell.

[Rolling bearing assembly].

Hammering method: a method of assembling by adding external force to the inner ring or outer ring of the bearing through a hand hammer or a soft metal sleeve. It is only suitable for the assembly of small bearings.

Press-in method: that is, the assembly of bearings is carried out with a press instead of manual loading.

Heating method: the most commonly used method. It is used in larger machinery. Place the bearing in the oil tank and heat it evenly to about 100 degrees, and immediately install it on the shaft after taking it out.

When heating, the bearing should not be placed on the bottom surface of the fuel tank, but should be 50 70mm away from the bottom surface of the fuel tank. It can be achieved by placing a mesh grid in the tank or lifting the bearing with a hook. It can be heated by electric furnace, or burned.

If a bearing heater is used to heat a bearing, the heating time is selected according to the size of the bearing.

This is the assembly process of rolling bearings.

1.The radial runout of the outer ring of a complete set of bearings, the difference between the maximum and minimum radial distance between the outer diameter surface and the relative inner ring when the outer ring is fixed at different angular positions. At the angular position of the above points or near them, the rolling elements on both sides should be in contact with the inner and outer ring raceways or the inner ring back flange (tapered roller bearing), that is, the bearing parts are in the normal relative position.

2.When the runout SIA inner ring of the inner ring of the complete set of bearing facing the raceway is at different angular positions, the difference between the maximum and minimum axial distance between the reference end face of the inner ring and a fixed point relative to the outer ring is equal to half of the contact diameter of the inner ring raceway at the radial distance from the axial line of the inner ring. Both the inner and outer raceways should be in contact with all rolling elements.

3.When the runout sea outer ring of the outer ring end of the complete set of bearings facing the raceway is at different angular positions, the difference between the maximum and minimum axial distance between the reference end face of the outer ring and a fixed point relative to the inner ring at the radial distance from the axial line of the outer ring is equal to half of the contact diameter of the outer ring raceway. Both the inner and outer raceways should be in contact with all rolling elements.

4.The runout SD facing the inner hole is the difference between the maximum and minimum axial distance between the plane perpendicular to the axial line of the ferrule and the end face of the ring datum at the radial distance from the axial line of the inner ring equal to half of the contact diameter of the raceway.

5.Contact angle.

The angle between the plane perpendicular to the bearing axis line (radial plane) and the resultant line of action (nominal line of action) transmitted to the rolling elements through the bearing ring or washer.

6.The diameter of the inner (outer) connected cylinder of a row of balls in the inner (outer diameter) bearing of the ball set.

7.The diameter of the inner (outer) radial contact cylinder of a row of rollers in a roller bearing in the inner (outer) radial contact roller bearing of the roller group.

8.The distance between the two theoretical end faces (backsides of the washer) of the bearing nominal width ring. It is used to define the radial bearing width (thrust bearing height).

9.The distance between the axial line of the radial bearing and the intersection of the two tangent planes of the actual end face of the ring that defines the width of the bearing. The bearing width is defined by the inner ring face and the outer ring face.

10.The difference between the actual width of the bearing and the nominal width of the bearing.

11.The difference between the maximum and minimum radial distance between the surface of the inner bore and a fixed point of the relative outer ring when the radial runout of the inner ring of the complete bearing is at different angular positions. At the angular position of the above points or near the two sides of the rolling elements should be in contact with the inner and outer ring raceways or the inner surface of the inner ring back flange (tapered roller bearing), that is, the bearing parts are in the normal relative position.

Different bearings have different processes when they are installed, and you can consult the dealer if you buy them.