Pay Attention To These Details When Machining Shaft Parts

Shaft parts are a common type of component, with a rotating structure and a length generally greater than the diameter. They are widely used in various mechanical equipment to support transmission components, transmit torque, and withstand loads. The processing of shaft parts should follow certain rules. You can learn about the specific processing steps and some issues that need to be noted through this article.
1、 Basic processing route for shaft parts
The main machining surfaces of shaft parts are outer circular surfaces and common special shaped surfaces. Therefore, suitable machining methods should be selected based on various accuracy levels and surface roughness requirements. The basic processing routes can be summarized into four.
Firstly, the processing route is from rough turning to semi precision turning, and then to precision turning. This is also the main process route selected for needle cylindrical machining of commonly used material shaft parts; Secondly, from rough turning to semi precision turning, and then to rough grinding, a precision grinding processing route is adopted. For parts with high requirements for ferrous metal materials and accuracy, low surface roughness requirements, and the need for hardening, this processing route is a good choice because grinding is the ideal subsequent processing process; The third route is from rough turning to semi precision turning, and then to precision turning, diamond turning. This processing route is specifically used to process non-ferrous metal materials, because the hardness of non-ferrous metals is small and it is easy to block the gaps between sand particles. Grinding is usually not easy to obtain the required surface roughness, and precision turning and diamond turning processes must be used; One processing route is from rough turning to semi precision turning, and then to rough grinding, precision grinding, and finishing. This route is often used for parts made of black metal materials that have been hardened and require high precision and low surface roughness values.
2、 Prefabrication of shaft parts
Before turning the outer circle of shaft parts, some preparation processes need to be carried out, which is the pre processing process of shaft parts. The important preparation process is straightening. Because the workpiece blank often undergoes bending deformation during manufacturing, transportation, and storage. In order to ensure reliable clamping and uniform distribution of machining allowance, various presses or straightening machines are used for straightening in the cold state.
3、 Positioning reference for machining shaft parts
Firstly, the central hole of the workpiece is used as the positioning reference for machining. In the processing of shaft parts, the coaxiality of the outer circular surfaces, conical holes, and threaded surfaces, as well as the perpendicularity of the end face to the rotating axis, are important manifestations of positional accuracy. These surfaces are generally designed based on the centerline of the axis, positioned with a central hole, in accordance with the principle of overlapping the reference lines. The center hole is not only the positioning reference for turning machining, but also the positioning and inspection reference for other machining processes, in accordance with the principle of unified reference. When using two center holes for positioning, multiple outer circles and end faces can be machined with great limitations in one clamping process.
Secondly, the outer circle and center hole are used as positioning benchmarks for machining. This method effectively overcomes the disadvantage of poor rigidity in locating the center hole, especially when machining heavy workpieces, which can cause unstable clamping and the cutting amount cannot be too large. By using the outer circle and center hole as the positioning reference, there is no need to worry about this issue. During rough machining, the method of using the outer circular surface of the shaft and a central hole as the positioning reference can withstand large cutting torque during machining, and is a common positioning method for shaft parts.
The third is to use the two outer circular surfaces as the positioning reference for processing. When machining the inner hole of a hollow shaft, the central 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 machine tool spindles, two supporting journals are often used as positioning benchmarks, which can effectively ensure the coaxiality requirements of the taper hole relative to the supporting journal and eliminate errors caused by non overlapping benchmarks.
Afterwards, the conical plug with a central hole is used as the positioning reference for processing. This method is commonly used in the machining of the outer surface of hollow shafts.
4、 Clamping of shaft parts
The machining of the cone plug and cone sleeve spindle must have high machining accuracy, where the center hole is not only the positioning reference for its own manufacturing, but also the reference for the precision machining of the hollow shaft outer circle. It is necessary to ensure that the cone surface on the cone plug or cone sleeve spindle has a high coaxiality with the center hole. Therefore, when selecting the clamping method, attention should be paid to minimizing the number of installation times of the cone plug, in order to reduce the repeated installation error of the parts. In actual production, after the installation of the cone plug, it is generally not removed or replaced in the middle of the machining process before it is completed.