Details that need to be paid attention to during CNC machining of the long axis of a CNC lathe The axis is a common part and is a rotating body whose length is generally greater than its diameter. It is widely used in various mechanical equipment to support transmission components, transmit torque and withstand...
Details that need to be paid attention to during CNC machining of long axis of CNC lathe
The 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 components, transmit torque and bear loads. The handling of shaft parts must follow certain rules. This article will introduce the specific processing steps and some issues that need attention.
Basic processing route of shafts. The main processing surfaces of shaft parts are outer surfaces and ordinary special surfaces. Therefore, the most appropriate processing method should be selected for various accuracy levels and surface roughness requirements. The basic processing routes can be summarized into four types.
1. From rough turning to semi-finished product turning to fine turning, this is also the most important process route for processing the needle outer ring of general external shaft parts.
2. From rough CNC machining to semi-finish CNC machining, then to rough grinding, and finally the fine grinding machining route. For ferrous metal materials and precision requirements, small surface roughness requirements and hardened parts are required, this machining route is the best choice, since grinding is the ideal follow-up process.
3. From rough turning to semi-finished turning, then to fine turning and diamond turning, this processing route is specially used to process non-ferrous metal materials. Because the hardness of non-ferrous metals is small, it is easy to block the gaps between sand grains, and it is usually difficult to obtain the required grinding results. To achieve the required surface roughness, finishing and diamond turning processes must be used; the final processing route is from rough machining to semi-finishing, then to rough grinding and fine grinding.
4. Finishing, this route is a processing route commonly used for hardened ferrous metal materials that requires high precision and low surface roughness.
CNC lathe processing
Reprocessing of P axis
Before turning the outside of the shaft section, some preparation is required. This is the pre-machining 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 even distribution of machining allowance, alignment is performed in a cold state by various presses or straightening machines.
Axis machining positioning standards
1. Use the center hole of the workpiece as the processing positioning benchmark. In the processing of shaft parts, the coaxiality of each outer circular surface, tapered hole and thread surface, and the perpendicularity of the end face and the rotation axis are important manifestations of position 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 center hole is not only the positioning benchmark for CNC turning, but also the positioning benchmark and inspection standard for other turning processes. The processing process conforms to the principle of unified standards. When positioning with two center holes, multiple outer circles and end faces can be processed in one clamping.
3. The outer circle and center hole are used as the positioning reference for processing. This method effectively overcomes the disadvantage of poor positioning rigidity of the center hole. Especially when processing heavier workpieces, the positioning of the center hole may cause unstable clamping, and the cutting amount cannot 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 large cutting moments during the machining process. It is the most commonly used positioning method for shaft parts.
Use two outer circular surfaces as machining positioning references. When processing the inner hole of a hollow shaft, the center hole cannot be used as the positioning datum. The two outer circular surfaces of the shaft should be used as the positioning datum. When processing machine tool spindles, two support journals are often used as positioning datums, which can effectively ensure the concentricity of the tapered hole relative to the support journals and eliminate errors caused by datum misalignment.
Use the taper plug with the center hole as a reference for machining positioning. This method is most commonly used for machining the outer surface of hollow shafts.
CNC lathe long axis processing
Shaft clamping
The processing of taper plugs and taper mandrels must have high processing accuracy. The center hole is not only the positioning reference made by yourself, but also the 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 selecting a clamping method, attention should be paid to minimizing the number of installations of the taper plug, thereby reducing repeated installation errors of parts. In actual production, after the taper plug is installed, it is generally not removed or replaced midway before processing.