1) Dimensional accuracy of seamless steel tubes
In order to determine the position of the axis, its dimensional accuracy (IT5 ~ IT7) is usually required. The accuracy of assembly driver journal size is usually low (IT6 ~ IT9).


(2) Geometric Accuracy of Seamless Steel Tubes
Geometric accuracy of axle components mainly refers to the roundness and cylindricity of journal, outer cone, Mohs cone, etc., and should be limited to tolerance. The precision of inner and outer circles of 40Cr seamless steel pipe is required to be high, and the allowable deviation should be marked on the drawing.


(C) Position accuracy of seamless steel tube
The position accuracy requirement of the axle parts mainly depends on the position and function of the center axle of the machine. Usually it is necessary to ensure that the Journal of the drive body needs to be coaxed to support the journal, otherwise it will affect the transmission accuracy of the transmission device (gear, etc.) and produce noise. For normal precision axles, the radial runout of the supporting axle relative to the supporting journal is usually 0.01 to 0.03mm, and the high precision axle (e.g., the main axle) is usually 0.001 to 0.005mm.


(D) Surface roughness of seamless steel tubes
Generally, the surface roughness of the diameter of 40Cr seamless steel tube bearing is Ra2.5-0.63 micron, and that of the supporting shaft is 40.63-0.16 micron.