Process requirements for machining shaft parts
1. Dimensional accuracy
Journal is the main component of shaft parts, which affects the rotation accuracy and working state of shaft. The diameter accuracy of the journal is usually IT6 ~ 9 according to its application requirements, and the precision journal can reach it5.
2. Geometric accuracy
The geometric accuracy of the Journal (roundness, cylindricity) should generally be limited to the diameter tolerance points. For those requiring high geometric accuracy, the allowable tolerance can be specified separately on the part drawing.
3. Position accuracy
It refers to the coaxiality of the mating Journal of the assembled transmission part relative to the supporting Journal of the assembled bearing, which is expressed by the radial circular runout of the mating journal to the supporting journal; According to the use requirements, it is specified that the high-precision shaft is 0.001 ~ 0.005mm, while the general precision shaft is 0.01 ~ 0.03mm. In addition, there are requirements for the coaxiality of the inner cylindrical surface and the perpendicularity of the axial positioning end face and the axis line.
4. Surface roughness
According to the different working parts of the parts, there can be different surface roughness values. With the increase of the machine running speed and the improvement of precision, the surface roughness value of shaft parts is required to be smaller and smaller.
5. It is not allowed to use when the bearing surface is discolored
When the surface of the alloy bearing liner is yellow, it is not allowed to use it. There is no denuclearization within the specified contact angle. The denuclearization area outside the contact angle shall not be greater than 10% of the total area of the non-contact area. The reference end face of the gear (worm gear) and the shaft shoulder (or the end face of the positioning sleeve) shall fit together, and it cannot be checked with a 0.05mm feeler gauge. The perpendicularity between the gear reference end face and the axis shall be ensured.
6. Contact surface
After assembly, the outer ring of the bearing should be in uniform contact with the end face of the bearing cover at the positioning end. After installation, the rolling bearing should rotate flexibly and stably by hand. The joint surface of the upper and lower bearing shells should be closely pasted and cannot be checked with a 0.05mm feeler gauge; When fixing the bearing bush with the locating pin, the reaming and pin allocation shall be carried out under the condition that the opening surface and end face of the bush are flush with the opening surface and end face of the relevant bearing hole. The pin shall not loosen after being driven.
The accuracy requirements of shaft parts are relatively high, so the machining process requirements of shaft parts should also be more strict, so as to better ensure that the mechanical equipment can operate better and have a longer service life.