Sliding bearings are important components that support the shaft and ensure its center stability. They are installed in the bearing housing and can be assembled in various forms as needed. Below is a brief explanation of the assembly requirements for sliding bearings.
1. Assembly of tiles and housing
There are copper bearings, cast iron bearings, Babbitt alloy bearings, and some non-metallic bearings. Regarding the self structure of tiles, some tiles are directly made of a certain material or alloy, while others are composite bodies. For example, the large tile of a kiln is composed of a tile body and a tile lining, while the large tile of a mill is poured with a tile lining on the tile body. The other structures of tiles are also different, for example, we call the ones that have not been separated "sets". Today we will mainly talk about split type bearing shells.
1.1 Split type Bearing and Bearing Housing and Assembly
Split type bearing shells are divided into upper and lower parts, and the middle joint surface can be adjusted by adding shims. But for cement enterprises, kiln grinding does not require the synthesis of whole tiles, only the lower tiles or two-thirds of the lower tiles are needed.
The assembly of the bearing shell and the bearing housing generally adopts a small gap (0.01mm) or small interference fit (0.00-0.04mm) between the outer circle of the bearing shell and the inner hole of the bearing housing. The contact between the outer circle of the lower bearing shell and the bearing housing should reach more than 60%, and the distance between the contact marks should be controlled within 5mm. The inner side of the bearing skirt and the bearing housing should achieve a seamless fit. To prevent misalignment during operation, positioning pins should be added to the diagonal of the tile; In order to prevent the tile from rotating inside the tile housing, a positioning pin should be installed between the tile back and the tile housing. The tile cover and lower tile housing are positioned with a stopper and locating pin, and one side of the stopper adopts interference fit, with an interference fit of generally 0.04-0.06mm, while the other side adopts clearance fit, with a clearance of generally 0.03-0.15mm.
1.2 Coordination between watts and shaft
The fit between the tile and the shaft is crucial, with requirements for top clearance and side clearance to facilitate the formation of a lubricating oil film, reduce friction, and extend lifespan. If the clearance is not appropriate, it will not only cause the bearing to heat up, but also cause vibration, and even lead to shaft burning and bearing burning accidents.
The clearance between the bearing shells is related to factors such as equipment operating accuracy, speed, load size, bearing material, lubricating oil, etc., and should be selected correctly. However, for cement equipment, the top clearance can be selected according to the following formula:
A=kd
In the formula, a represents the top gap mm. k is the coefficient, ranging from 0.0015 to 0.002.
D is the nominal diameter of the shaft in millimeters.
Side clearance of bearing shell
B=(0.5~1.0) a
In the formula: b is the side gap mm, and a is the top gap mm.
The gap between the outer side of the bearing shell skirt and the shaft shoulder can be divided into two steps. For positioning the bearing shell, it can be controlled according to the sum of the clearances on both sides not exceeding 0.2mm; For non positioning end bearing shells, control should be based on the expansion and contraction of the running axis.
Regarding the detection of clearances between bearing shells, axial clearances can be measured directly with a feeler gauge, and side clearances can also be measured by first attaching the bearing shell to the shaft and then using a feeler gauge. However, the detection of the top clearance is difficult to measure with a feeler gauge due to the influence of the shaft shoulder, and can be indirectly measured using the lead pressure method.
Adjustment of tile clearance: The tile mouth clearance and tile axial clearance can be achieved through scraping and machining methods, while the top clearance can be adjusted by adding or removing shims to the tile mouth.
2. Scratching and grinding of tiles
Apart from assembly, scraping and grinding the tiles is just the most important task. Firstly, it is necessary to determine the angle of the tile to the shaft, and secondly, to ensure that the contact between the shaft and the tile meets the requirements. For cement enterprises, the tile is mainly made up of kiln grinding, consisting of tile body and tile lining. The outer spherical surface of the tile body is in contact with the spherical tile housing, the outer circle of the tile lining is in contact with the inner hole of the tile body, and the tile lining is in contact with the shaft. The enveloping angle is generally between 60-75 degrees, and a large enveloping angle is not conducive to the formation of oil wedges and lubrication; The package angle is too small, resulting in a decrease in load-bearing capacity and rapid wear.
The measurement method for the angle of the package: Since the kiln grinding tile only has the upper tile and not the lower tile, the detection refers to the lower tile. When scraping tiles, first calculate and draw the corner section based on the corner, and then open the tile mouth, gradually increasing from bottom to top. A feeler gauge can be used to measure the angle of the package. First, the tile and the axle buckle are combined, and it is considered that 0.05mm cannot be inserted to the bottom. Then, the angle of the package is calculated based on the depth of insertion of the feeler gauge. To detect the gap between tile openings at different depths, different thickness gauges can be used for measurement.
The requirement for scraping accuracy is that the distance between the contact marks between the spherical tile housing and the outer spherical surface of the tile tire should be less than 5mm, and the marks should gradually become lighter from the bottom to the tile mouth. The requirements for tile lining and tile tire are the same. The contact accuracy between the shaft and the tile lining is high, and the distance between the marks is less than 3mm.
2025 June 2nd Week Marginal Product Recommendation:
MG-EPB5Z Plastic Plain Bearings：
MG-EPB5Z Plastic Plain Bearings It is a high load material with excellent low friction factor. Marginal load application is acceptable and it is with good wear resistance both for hard and soft shafts. Continuous working temperature: -100℃～250℃; High load capacity; Higher speed is permissible; Marginal pressure is permissible; Best performance for oscillating movement.
https://www.marginalbearings.com/plastic-plain-bearings/mg-epb5z-plastic-plain-bearings.html
