Shaft parts are a common type of parts. Their structure is a rotating body, and the length is generally larger than the diameter. They are widely used in various mechanical equipment to support transmission parts, transmit torque and bear loads. The processing of shaft parts should follow certain rules. You can learn about the specific processing steps and some problems that need attention through this article.

1、 Basic processing route of shaft parts

The main machining surfaces of shaft parts are cylindrical surfaces and common special surfaces. Therefore, appropriate machining methods should be selected according to various Accuracy grades and surface roughness requirements. There are four basic processing routes.

The first is the processing route from rough turning to semi fine turning, and then to fine turning, which is also the most important process route selected for the needle cylindrical machining of shaft parts of common materials;

Secondly, from rough turning to semi fine turning, then to rough grinding, and finally to fine grinding, which is the best choice for ferrous materials and parts requiring high precision, low surface roughness and hardening, because grinding is the most ideal subsequent processing procedure;

The third route is from rough turning to semi fine turning, and then to fine turning and diamond turning. This processing route is specially used for processing non-ferrous metal materials. Because the non-ferrous metal has a small hardness and is easy to block the gap between sand grains, it is usually difficult to obtain the required surface roughness by grinding, so precision turning and diamond turning processes must be adopted;

The last processing route is from rough turning to semi fine turning, then to rough grinding, fine grinding, and finally finishing. This route is often used for parts with high precision and low surface roughness after hardening of ferrous materials.

2、 Pre machining of shaft parts

Before turning the outer circle of shaft parts, some preparatory procedures must be carried out first, which is the pre machining process of shaft parts. The most important preparation process is alignment. Because the workpiece blanks often bend and deform in the process of manufacturing, transportation and storage. In order to ensure reliable clamping and uniform machining allowance distribution, straightening is carried out by various presses or straightening machines in cold state.

3、 Positioning datum for machining shaft parts

First, the center hole of the workpiece is used as the positioning reference for machining. In the processing of shaft parts, the coaxiality of each outer circular surface, taper hole and thread surface, and the perpendicularity of the end face to the rotation axis are important manifestations of position accuracy. These surfaces are generally designed based on the center line of the shaft and positioned with the center hole, which conforms to the principle of datum coincidence. The center hole is not only the positioning benchmark for turning, but also the positioning benchmark and inspection benchmark for other processing procedures, which conforms to the principle of benchmark unification. When two center holes are used for positioning, multiple outer circles and end faces can be machined in one clamping to the maximum extent.

Secondly, the outer circle and the center hole are used as the positioning datum. This method effectively overcomes the disadvantage of poor positioning rigidity of the center hole, especially when processing heavy workpieces, the positioning of the center hole will cause unstable clamping and the cutting amount cannot be too large. If the outer circle and the center hole are used as the positioning datum, there is no need to worry about this problem. In rough machining, the method of using the outer circle surface of the shaft and a central hole as the positioning reference can bear a large cutting torque in machining, which is the most common positioning method for shaft parts.

The third is to use the two outer circular surfaces as the positioning benchmark for machining. When machining 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 machine tool spindle, the two support journals are often used as the positioning benchmark, which can effectively ensure the coaxiality of the taper hole relative to the support journal and eliminate the error caused by the misalignment of the benchmarks.

Finally, the taper plug with a central hole is used as the positioning benchmark for machining. This method is most commonly used in the machining of the outer circle surface of the hollow shaft.

4、 Clamping of shaft parts

The machining of taper plug and taper sleeve mandrel must have high machining accuracy. The core hole is not only the positioning benchmark of its own manufacturing, but also the benchmark of hollow shaft outer circle finish machining. It must be ensured that the conical surface on the taper plug or taper sleeve mandrel has high coaxiality with the central hole. Therefore, when selecting the clamping method, attention should be paid to reducing the installation times of cone plugs as far as possible, so as to reduce the repeated installation error of parts. In actual production, after the cone plug is installed, generally speaking, it will not be removed or replaced in the middle of processing before the processing is completed.