Technical accuracy requirements for shaft parts

The shaft is one of the typical parts commonly found in machining. In the course of consumption, air compressor bearing parts have to go through many cold and hot processing steps. In order to satisfy the request of small amount, high efficiency and high quality, bearing steel should have good processing performance. In order to increase the wear of the bearing parts, maintain the bearing accuracy and stability, and extend the service life, the bearing steel should have good wear resistance. It is mainly used in machinery to support gears such as gears, pulleys, cams and connecting rods to transmit torque. According to different structural forms, the shaft can be divided into stepped shaft, tapered mandrel, optical axis, hollow shaft, crankshaft, camshaft, eccentric shaft, various lead screws, etc. Among them, the stepped drive shaft is widely used, and its processing technology can be comprehensive. The ground reflects the processing law and commonality of the shaft parts.

According to the function and working conditions of the shaft parts, the technical requirements are mainly in the following aspects:

1 dimensional accuracy

The main surfaces of shaft parts are often two types: one is the outer cylindrical journal that fits 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 dimensional accuracy is high, usually IT. 5~IT7. The other type is the journal that cooperates with all kinds of transmission parts, that is, the matching journal, its precision is slightly lower, often IT6~IT9.

2 geometric accuracy

Mainly refers to the roundness and cylindricity of important surfaces such as journal surface, outer conical surface and tapered hole. In the course of consumption, air compressor bearing parts have to go through many cold and hot processing steps. In order to satisfy the request of small amount, high efficiency and high quality, bearing steel should have good processing performance. For example, cold, thermoforming properties, machinability, hardenability, and the like. The error should generally be limited to the dimensional tolerances. For precision shafts, the geometric accuracy of the parts is to be specified separately.

3 mutual position accuracy

Including the inner and outer surfaces, the coaxiality of the important axial plane, the radial runout of the circle, the perpendicularity of the important end face to the axis, and the parallelism between the end faces.

4 surface roughness

The machined surface of the shaft has a roughness requirement, which is generally determined by the possibility of processing and economy. The support journal is usually 0.2 to 1.6 μm, and the transmission member is 0.4 to 3.2 μm.

5 other

Heat treatment, chamfering, chamfering and appearance modification.