How to measure bearing and shaft hole dimensions?

一、 bearing hole measurement

Bearing hole measurement can be measured using the inner diameter meter on the outer diameter micrometer after checking the reference size, at the same time, also need to measure the roundness and cylindricity of the bearing hole. The burnt out bearing often reduces the diameter of the bearing hole at the opening and the roundness is out of tolerance, which is very unfavorable to the normal work of the bearing. If the positioning surface of the connecting rod bolt is loose, the connecting rod bearing cover will shift and the roundness of the bearing hole will be out of tolerance. The roundness error of bearing bore should be controlled within the dimensional tolerance, and the cylindricity should be strictly controlled.

二、 the main size of the bearing measurement

（1）Bearing thickness: the outer diameter micrometer fixed probe is transformed from a plane into a sphere, which can be used to measure the bearing thickness. Bearing thickness should generally be controlled within the range of 0.005~0.010 mm, otherwise it will make the bearing inner diameter out of tolerance. The bearing is slightly thinner at the near opening, which should be noted when measuring.

（2）The fit tightness of bearing and bearing hole: the fit tightness is guaranteed by the free popping of bearing and the height of the residual surface. In the method of measuring the height of the remaining surface: assemble the bearing according to the regulations, fasten the bearing cover bolt to the specified torque, loosen one of the bolts, and measure the gap at the bearing cover interface with a gauge. The value should be within 0.05~0.15 mm.

 (3) Bearing inner diameter: before measurement, it is necessary to assemble the bearing according to the regulations and tighten the bearing cover bolt according to the regulations. With the inner diameter scale, the colonel of the outer diameter micrometer measures the benchmark size, and the thinning area should be avoided when measuring. The difference between the bearing inner diameter and the corresponding journal outer diameter is the fit clearance.

 (4) Coaxiality of the main bearing inner hole: the coaxiality error of the main bearing inner hole 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 runout of the spindle neck is within the specified tolerance, check the joint impression of the spindle neck and bearing. If the position of the main bearing is 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.

Two, the bearing material is generally measured in the following points: outer diameter size, inner diameter size, height, this is the basic three sizes to detect. Generally use caliper and micrometer, or clip measuring block to dial meter, accurate point. With the instrument can be bearing inside diameter beat and outside diameter beat. The main instrument is to detect the accuracy level of bearings.