Machining and technical accuracy requirements of shaft parts

Shaft is one of the typical parts in machining. It is mainly used in the mechanical support gear, pulley, cam and connecting rod and other transmission parts to transmit torque. According to the different structure, the shaft can be divided into step shaft, taper mandrel, optical shaft, hollow shaft, crankshaft, camshaft, eccentric shaft, various screw, etc. the step drive shaft is widely used, and its processing technology can comprehensively reflect the processing law and common character of shaft parts.
According to the function and working conditions of shaft parts, the technical requirements are mainly in the following aspects:
1. Dimensional accuracy
The main surface of shaft parts is usually divided into two types: one is the outer circular journal which matches the inner ring of the bearing, that is, the bearing journal, which is used to determine the position of the shaft and support the shaft. The dimension accuracy is required to be high, usually it 5-it7; The other is the journal which fits with various transmission parts, that is, the journal, which has a lower precision, and is often it6-it9.
2. Geometric accuracy
It mainly refers to the roundness and cylindricity of the important surfaces such as journal surface, outer circular cone and cone hole. The error shall be limited to the tolerance range of dimension. For precision shaft, the geometric precision of the precision axis shall be specified separately on the part drawing.
3. Mutual position accuracy
It includes the coaxiality of inner and outer surfaces, the coaxiality of important axis surfaces, the radial runout of the circle, the verticality of the important end faces to the axis line, and the parallelism between the end faces.

4. Surface roughness

The machining surface of the shaft has the requirement of roughness, which is generally determined according to the possibility and economy of machining. The bearing journal is usually 0.2-1.6 μ m. The matching Journal of the transmission parts is 0.4-3.2 μ m。

5. Others

Requirements for heat treatment, chamfering, chamfering and appearance modification.