What is self-aligning roller bearing?

The self-aligning roller bearing has two rows of rollers. The outer ring has one common spherical raceway, and the inner ring has two raceways, which are inclined to form an angle with respect to the bearing axis. This ingenious structure enables it to have automatic centering performance, so it is not vulnerable to the influence of the angle between the shaft and the bearing housing on the error or shaft bending. It is suitable for the occasion where the angle error is caused by installation error or shaft deflection. The bearing can not only bear the radial load, but also bear the axial load of two-way action.

The inner holes of the self-aligning roller bearings are cylindrical and conical, and the taper of the conical hole is 1:30 and 1:12. The conical inner hole bearing is equipped with a locking sleeve or a withdrawal sleeve, so that the tapered inner hole self-aligning ball bearing can be conveniently and quickly assembled on the smooth shaft or the ladder machine shaft.

The models of self-aligning roller bearings include: self-aligning roller bearings (20000CC type); Tapered hole self-aligning roller bearing (20000CCK type); Self aligning roller bearing (20000CC/W33 type); Tapered hole self-aligning roller bearing (20000CCK/W33 type); Self aligning roller bearing (20000CCK+H type) installed on the clamping sleeve; There are 6 kinds of self-aligning roller bearings (20000CCK/W33+H type) installed on the adapter sleeve.

Self aligning roller bearing has two rows of rollers, which mainly bear radial load, and can also bear axial load in any direction. It has high radial load capacity, especially suitable for working under heavy load or vibration load, but can not bear pure axial load. The outer race raceway of this type of bearing is spherical, so its centering performance is good, and it can compensate the coaxial error.

There are two rows of symmetrical spherical rollers, the outer ring has a common spherical raceway, and the inner ring has two raceways inclined at an angle with the bearing axis, which has good centering performance. When the shaft is forced to bend or installed unevenly, the bearing can still be used normally. The centering performance varies with the bearing size series. Generally, the allowable centering angle is 1~2.5 degrees, and the load capacity of this type of bearing is large, In addition to bearing radial load, the bearing can also bear the axial load of two-way action, with good impact resistance. Generally speaking, the allowable working speed of self-aligning roller bearing is low.

Self aligning roller bearings are divided into symmetrical spherical roller and asymmetrical spherical roller according to the shape of roller cross-section. The asymmetrical self-aligning roller bearing is an early product, mainly for the maintenance service of the main engine. When the main engine is newly designed, the symmetrical self-aligning roller bearing is rarely used. The internal structure has been comprehensively improved and designed, and the parameters have been optimized. Compared with the early self-aligning roller bearing, it can withstand greater axial load, The operating temperature of this bearing is low, so it can meet the requirements of higher speed. According to whether the inner ring has a rib and the cage used, it can be divided into C type and CA type. The characteristics of C type bearing are that the inner ring has no rib and uses a steel plate pressed cage. The characteristics of CA type Trien bearing are that both sides of the inner ring have rib and use a lathe made solid cage. In order to improve the lubrication of the bearing, the user can be provided with a self-aligning roller bearing with an annular oil groove and three oil holes in the outer ring, which is represented by the rear bearing code/W33. Self aligning roller bearing with inner ring oil hole can also be supplied according to the user’s requirements. In order to facilitate the customer’s loading and unloading and bearing replacement, self aligning roller bearing bearing with taper in the inner hole can also be provided. The taper of the taper hole is 1:12, and the rear code is K. In order to meet the requirements of special users, the bearing with taper in the inner hole is 1:30, and the rear code is K30. Bearing with taper in inner hole can be directly installed on tapered journal with locknut, or installed on cylindrical journal with locking sleeve or withdrawal sleeve.

Classification of self-aligning roller bearing

Self aligning roller bearings are divided into cylindrical bore and conical bore. Self aligning roller bearing (153000 or 113000 type) with a taper of 1:12 and a rear self-aligning roller bearing (K30) with a taper of 1:30 respectively. When this type of bearing is matched with the conical shaft, the inner ring can move along the axial direction to adjust the radial clearance of the bearing.

Main Use of self-aligning roller bearing

Main applicable cages: pressed steel plate reinforced cages (suffix E, few in China). Stamped steel plate cage (suffix CC), glass fiber reinforced polyamide 66 cage (suffix TVPB), and machined brass two-piece cage (suffix MB). Machined brass one-piece cage (suffix CA), stamped steel plate cage in vibration occasions (suffix JPA). Brass cage for vibration (suffix EMA). For the same structure, the codes on the bearings may be different.

Main applications: paper making machinery, speed reducer, railway vehicle axle, rolling mill gearbox bearing seat, rolling mill roller, crusher, vibrating screen, printing machinery, woodworking machinery, various industrial reducers, vertical centering bearing with seat.

Installation of self-aligning roller bearing

The self-aligning roller bearing is equipped with a drum roller bearing between the inner ring with two raceways and the outer ring with a spherical raceway. The curvature center of the outer ring raceway surface is consistent with the bearing center, so it has the same centering function as the automatic self-aligning ball bearing. When the shaft and housing are flexed, the load and axial load in two directions can be adjusted automatically. Large radial load capacity, suitable for heavy load and impact load. The inner diameter of the inner ring is a tapered bearing, which can be directly installed. Or install it on the cylindrical shaft with a set sleeve and a disassembly cylinder. The cage is made of steel plate pressing cage, polyamide shaped cage and copper alloy car made cage.

For self-aligning bearings, when installing the bearing with shaft into the box shaft hole, the use of intermediate mounting ring can prevent the outer ring from tilting and rotating. It should be remembered that the ball of self-aligning ball bearings of some sizes protrude from the side of the bearing, so the middle mounting ring should be recessed to prevent damage to the ball. A large number of bearings are generally installed by mechanical or hydraulic pressing method. [3]

For separable bearings, the inner ring and outer ring can be installed separately, which simplifies the installation process, especially when both the inner and outer rings need interference fit. When installing the shaft with the inner ring installed in place into the bearing housing with the outer ring, you must check whether the inner and outer rings are correctly aligned to avoid scratching the bearing raceway and rolling parts. If cylindrical and needle roller bearings use inner rings without flange flanges or inner rings with flange edges on one side, it is recommended to use mounting sleeves. The outer diameter of the sleeve shall be equal to the diameter F of the inner race race, and the tolerance standard for machining shall be d10. It is better to install the needle bearing of pressing outer ring with mandrel.

Attention of self-aligning roller bearing

The preload of the self-aligning roller bearing is carried out at room temperature, but in the working state, the preload of the bearing will change when the system micro stretching temperature rises, so this factor should be taken into account when setting the preload.

It requires the ability to set the size, speed, and other conditions for the rational use of self-aligning roller bearing preload to ensure transmission of life. If the pre tightening force is too large, the power consumption may even lead to overheating. If the preload is too small, under the action of body load, shaft rolling, and the gap between the outer rings, there will be runout, running, and transmission accuracy to reduce the increase in noise, which affects gear engagement, and serious damage to teeth and bearings.

Assemble according to different self-aligning roller bearings, for example, rotate the bearing pre tightening nut that directly compresses the inner race of the inner bearing axially, and the inner and outer rings to eliminate the gap and achieve the purpose of bearing pre tightening force. Achieve common use: first, far more than the pre installed bearing, the last nut, and then back 1/4 turns. Assembly method, this method has the advantages of less investment, simple, practical, consistent good quality under the premise of tapered roller bearings, it can be used.

  1. Electric hot plate heating method: place the bearing on the electric hot plate with a temperature of 100 ℃ for a few minutes. This method is the most simple. If the bearing is turned over several times, it can bear heat evenly and has high efficiency. This method can be used for large and small self-aligning roller bearings
  2. The electric furnace heating method places the bearings in a closed automatic temperature control electric furnace for heating. The heating is uniform, temperature control is accurate, and the heating is fast. It is suitable for heating many bearings in a batch
  3. The induction heating method uses the induction heater to quickly, reliably and cleanly heat the self-aligning roller bearing to the required temperature, which is especially suitable for the occasion of tight fitting of the inner ring. Since only the inner ring is heated, but the outer ring is rarely heated, it can be easily installed on the shaft and into the seat hole
  4. The electric bulb heating method uses a 50W electric bulb to heat the self-aligning roller bearing, which can ensure that the heating temperature is about 100 ℃. The smaller bearing can be directly placed on the bulb, and the larger bearing can be placed in the conical cover of the bulb. The conical cover can prevent the heat loss of the bulb, and make the heating uniform. The conical cover can be adjusted up and down. It can be used to heat bearings of different sizes within a certain range. If a far-infrared bulb is used, note that the bulb direction should be downward, In order to avoid infrared rays harmful to human eyes, this bulb can be energy-saving bulb heating method is applicable to a small number of infrequent needs; When heating the bearing, the bulb can also be used for lighting at ordinary times. In addition, no other equipment is required
  5. Oil tank heating method This is a widely used traditional heating method. A metal mesh is set 50~70mm from the oil tank to the bottom, and the bearing is placed on the wire. The large bearing should be lifted with a hook and should not be placed directly on the tank bottom, to prevent the bearing part contacting the tank bottom from being heated too high locally, or the dirt precipitated at the tank bottom from entering the bearing oil tank heating method. The following points should be noted: mineral oil without corrosivity and good thermal stability should be used, preferably transformer oil, Both the oil and the container should be kept clean. The capacity of the oil sump should depend on the size and oil volume of the heated self-aligning roller bearing. If the container is too small, the temperature of the bearing oil will drop quickly once it is put into continuous operation, and the effect will be poor

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