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Measurement Of Main Bearing Holes And Dimensions Of Bearings

Measurement 

(1) Measurement of bearing hole

For the measurement of the bearing hole, the inner diameter gauge can be used to check the reference size on the outer diameter micrometer, and the roundness and cylindricity of the bearing hole shall also be measured.

Burning out the bearing often reduces the diameter of the bearing hole at the opening and the roundness is out of tolerance, which is extremely unfavorable to the normal operation of the bearing. If the locating surface of the connecting rod bolt fits loosely, the connecting rod bearing cap will shift and the roundness of the bearing hole will exceed the tolerance.

The roundness error of bearing hole shall be controlled within the Measurement dimensional tolerance, while the cylindricity shall be strictly controlled.

(2) Measurement of main dimensions of bearing

① Bearing thickness: fix the outside micrometer and change the measuring head from plane to spherical surface, which can be used to measure the bearing thickness. The bearing thickness shall generally be controlled within the range of 0.005 ~ 0.010 mm, otherwise the inner diameter of the bearing will exceed the tolerance. The bearing has slight thinning near the opening, which should be paid attention to during measurement.

② Fit tightness of bearing and bearing hole: the fit tightness is guaranteed by the free spring opening of bearing and the height of surplus surface. Under Measurement the method of measuring the height of the remaining surface:

assemble the bearing according to the regulations, tighten the bolts of the bearing cover to the specified torque, loosen one of the bolts, and measure the clearance at the interface of the bearing cover with a feeler gauge, which shall be within the range of 0.05 ~ 0.15mm.

Measurement Of Main Bearing Holes And Dimensions Of Bearings

③ Bearing inner diameter:

before measurement, the bearing shall be installed according to the regulations and the bearing cover bolts shall be tightened according to the specified torque. The inner diameter gauge shall be used to measure after the reference dimension is measured with the outer diameter micrometer.

The thinning area shall be avoided during measurement. The difference between the bearing inner diameter and the corresponding journal outer diameter is the fit clearance.

④ Coaxiality of the inner hole of the main bearing: the coaxiality error of the inner hole of the main bearing is mainly caused by the coaxiality error of the bearing hole, and the coaxiality error of the bearing hole is caused by the deformation of the cylinder block.

When the radial circular runout of the main journal is within the specified tolerance, check the bite marks of the main journal and the bearing. If the bite marks of each main bearing are obviously inconsistent, it indicates that the coaxiality error is large, which can be solved by scraping, boring the bearing or replacing the cylinder block, otherwise it is difficult to ensure the normal operation of the engine.

Abnormal load of cage. If the installation is not in place, the inclination and the interference amount are too large, it is easy to reduce the clearance, aggravate the friction and heat generation, soften the surface, and premature abnormal spalling.

With the expansion of spalling, the spalling foreign matter enters the cage pocket, resulting in the operation block of the cage and additional load, which intensifies the wear of the cage. Such a deteriorated cyclic effect may cause the cage fracture.

Cage material defects and riveting defects may cause cage fracture. The countermeasures are to strictly control in the manufacturing process. The invasion of foreign matters is a common mode of cage fracture failure. Due to the intrusion of foreign hard foreign matters, the wear of cage and abnormal additional load may also lead to cage fracture.

Poor lubrication mainly refers to that the shaft is in poor oil state, which is easy to form adhesive wear and deteriorate the working surface state. The tears caused by adhesive wear are easy to enter the cage, resulting in abnormal load on the cage, which may cause cage fracture.

Bearing plays an important role in the field of machinery. Bearing can not only be used in machinery, but also be made into some craft toys. Bearing has had a great impact on our life.