xiehe model

Details that need attention in the process of CNC lathe long axis machining

A shaft is a common part, which is a rotating body whose length is generally greater than its diameter. It is widely used in various mechanical equipment to support transmission parts, transmit torque and bear load. The handling of shaft parts must follow certain rules. This article will introduce the specific processing steps and some issues that need attention.

The basic processing route of the shaft, the main processing surface of the shaft parts is the outer surface and the ordinary special surface, so the most suitable processing method should be selected according to various precision grades and surface roughness requirements. The basic processing routes can be summarized into four types.

1. The processing route from rough turning to semi-finished car and then to finish turning is also the most important process route for processing the needle outer ring of shaft parts with general outer materials.

2. From rough machining to semi-finishing, then to rough grinding, and finally adopt the fine grinding processing route. For ferrous metal materials and precision requirements, the surface roughness requirements are small, and hardened parts are required. This processing route is the best choice , because grinding is the ideal subsequent process.

3. From rough car to semi-finished car, and then to fine car and diamond car, this processing route is specially used for processing non-ferrous metal materials, because non-ferrous metals have low hardness and are easy to block the gaps between sand grains, and it is usually not easy to obtain the desired results from grinding. To obtain the required surface roughness, finishing and diamond turning processes must be used; the final processing route is from rough machining to semi-finishing, and then to rough grinding and fine grinding.

4. Finishing, this route is commonly used in hardened ferrous metal materials and requires high precision and low surface roughness.

Remachining of P axis

Before turning the outside of the shaft, some preparatory process is required. This is the pre-processing of the shaft part. The most important preparation process is straightening. Because workpiece blanks often bend during deformation during manufacturing, transportation and storage. In order to ensure reliable clamping and uniform distribution of machining allowance, straightening is carried out by various presses or straightening machines in a cold state.

Shaft machining positioning standard

1. Take the center hole of the workpiece as the processing positioning reference. In the processing of shaft parts, the coaxiality of each outer circular surface, taper hole and threaded surface, and the perpendicularity between the end surface and the rotation axis are important manifestations of positional accuracy. These surfaces are generally designed to be based on the centerline of the shaft and positioned with the center hole to comply with the principle of datum coincidence.

2. The central hole is not only

The positioning datum is also the positioning datum and inspection standard for other turning processes. The processing process is in line with the principle of unified standards. When two center holes are used for positioning, multiple outer circles and end faces can be processed in one clamping.

3. The outer circle and center hole are used as the positioning datum for processing. 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 may cause unstable clamping, and the cutting amount should not be too large.

4. Use the outer circle and center hole as positioning reference, so you don't have to worry about this problem. In rough machining, the outer surface and center hole of the shaft are used as the positioning reference method, which can withstand a large cutting moment during the machining process, and is the most commonly used positioning method for shaft parts.

Use two outer circular surfaces as processing positioning references. When machining the inner hole of the hollow shaft, the center hole cannot be used as the positioning reference, and the two outer circular surfaces of the shaft should be used as the positioning reference. When processing the spindle of a machine tool, two supporting journals are often used as positioning references, which can effectively ensure the concentricity of the taper hole relative to the supporting journals and eliminate errors caused by misalignment of the references.

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

Shaft clamping

The machining of taper plug and taper mandrel must have high machining accuracy. The center hole is not only a self-made positioning reference, but also a reference for finishing the outer circle of the hollow shaft. The taper on the cone or taper sleeve must be guaranteed. It has a high degree of concentricity with the central hole.

Therefore, when choosing the clamping method, attention should be paid to minimizing the number of installations of the taper plug, thereby reducing the repeated installation error of the parts. In actual production, after the taper plug is installed, it is generally not disassembled or replaced halfway before processing.