The positioning datum of Hangzhou shaft parts processing

Hangzhou shaft machining first takes the center hole of the workpiece as the positioning reference for machining. In the processing of shaft parts, the coaxiality of the outer surface, the tapered hole, and the threaded surface, and the perpendicularity of the end face to the axis of rotation are important manifestations of position accuracy. These surfaces are generally based on the centerline of the shaft as the design datum, and the center hole is used for positioning, which conforms to the principle of datum coincidence. The center hole is not only the positioning datum during turning, but also the positioning datum and inspection datum for other processing procedures, which conforms to the principle of unification of datums. When two center holes are used for positioning, multiple outer circles and end faces can be processed in one clamping to the maximum.

　　 Followed by the outer circle and center hole as the positioning reference for machining. This method effectively overcomes the shortcomings of poor positioning rigidity of the center hole, especially when processing heavier workpieces, the positioning of the center hole will cause unstable clamping, and the cutting amount cannot be too large. There is no need to worry about this problem if the outer circle and the center hole are used as the positioning reference. In rough machining, the method of using the outer surface of the shaft and a center hole as the positioning reference can withstand a large cutting torque during processing, which is a relatively common positioning method for shaft parts.

　　 The third is to use the two outer circular surfaces as the positioning reference for machining. When processing the inner hole of the hollow shaft, the center hole cannot be used as the positioning reference, so the two outer circular surfaces of the shaft should be used as the positioning reference. When machining the main shaft of a machine tool, the two supporting journals are often used as the positioning reference, which can effectively ensure the coaxiality requirements of the tapered hole relative to the supporting journal and eliminate errors caused by the reference misalignment.

　　 Finally, the taper plug with a center hole is used as the positioning reference for processing. This method is most commonly used in the outer surface machining of hollow shafts.