What technical issues need to be paid attention to during precision machining of shaft parts?
Precision shaft parts are a common part type. The structure is usually a rotating body, and the length is generally larger than the diameter. It is widely used in many automated equipment. It is used to support transmission parts, transmit torque and bear loads. . Shenzhen Hongweisheng Precision Technology Co., Ltd. is a powerful company specialized in custom processing and mass production of high-precision shaft parts. We have accumulated many years of experience in precision machining of shaft parts, and then we will take a detailed inventory for you. Some problems that need to be paid attention to when processing shaft parts are mainly counted from pre-processing, processing route, clamping and positioning reference, and come to understand them together.
1: Pre-processing of shaft parts (boosting)
Before turning shaft parts, shaft parts must be prepared. This is the pre-processing of shaft parts. The most important preparation process is straightening. Because the workpiece blank is often bent and deformed during manufacturing, transportation and storage. In order to ensure reliable clamping and uniform distribution of machining allowances, in the cold state, straightening is performed by various presses or straightening machines, which contributes to the later processing accuracy.
2: Basic machining route of shaft parts (process selection)
The main machining surfaces of shaft parts are cylindrical surfaces and common special surfaces, so you should choose a suitable machining method according to various accuracy levels and surface roughness requirements. Its basic processing routes can be summarized into four.
a. From rough turning to semi-finishing turning, and then to finishing turning, this is also the most important process route for the needle outer circle processing of shaft parts of commonly used materials.
b. From rough turning to semi-finishing turning, to finishing turning and diamond turning, this processing route is specially used for processing non-ferrous metal materials, because non-ferrous metals have a small hardness, and it is easy to block the gaps between the sand grains. Generally, grinding The required surface roughness is easily obtained, and the finishing and diamond turning processes must be adopted; the last processing route is from rough turning to semi-finishing turning, and then to rough grinding and finishing grinding.
c. From rough turning to semi-finishing turning, to rough grinding, and finally adopting the finishing grinding processing route. The requirements for ferrous metal materials and precision are higher, the surface roughness is smaller, and hardened parts are required. This processing route Is the best choice, because grinding is its ideal subsequent processing steps.
d. For light finishing, this route is a processing route that is often used for parts that have been hardened for ferrous metals, and have higher accuracy requirements and lower surface roughness values.
3: Clamping of shaft parts (processing preparation)
The machining of taper plugs and taper sleeve mandrels must have high machining accuracy. The center hole is not only the positioning reference made by itself, but also the benchmark for the external finishing of the hollow shaft. Has a high coaxiality with the center hole.
Therefore, when choosing a clamping method, care should be taken to minimize the number of times the cone plug is installed, so as to reduce repeated installation errors of parts. In actual production, after the cone plug is installed, generally it will not be removed or replaced in the middle of processing until the processing is completed.
Four: positioning reference for machining of shaft parts (processing process)
a. Use the center hole of the workpiece as the positioning reference for processing. In the processing of shaft parts, the concentricity of the extra round surface, the tapered hole, the thread surface, and the perpendicularity of the end surface to the rotation axis are all important manifestations of position accuracy. These surfaces are generally based on the centerline of the axis as the design basis, and are positioned with the center hole, which conforms to the principle of reference coincidence.
The center hole is not only the positioning reference during turning, but also the positioning reference and inspection reference for other machining processes, which conforms to the principle of unified standards. When two center holes are used for positioning, multiple external circles and end faces can be processed to the greatest extent in one clamping.
b. Use two outer circular surfaces as positioning reference for processing. When machining the inner hole of a 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 processing the spindle of a machine tool, the two support journals are often used as the positioning reference, which can effectively ensure the concentricity requirements of the tapered hole relative to the support journal, and eliminate errors caused by misalignment of the reference.
c. The outer circle and center hole are used as the positioning reference for processing. This method effectively overcomes the shortcomings of poor rigidity of the center hole positioning, especially when processing heavy workpieces, the center hole positioning will cause unstable clamping and the cutting amount cannot be too large. Don't worry about this problem by using the outer circle and center hole as the positioning reference. In rough machining, the method of using the outer surface of the shaft and a center hole as a positioning reference can withstand large cutting torques during machining. It is the most common positioning method for shaft parts.
d. Use the taper plug with the center hole as the positioning reference for processing. This method is most commonly used in the machining of the outer surface of a hollow shaft.
Through the above analysis, we can effectively avoid and prevent the problems often encountered in the processing of shaft parts, and the processing efficiency and accuracy can also be excellently guaranteed. Shenzhen Hongweisheng Precision Technology Co., Ltd. introduced the Japanese imported star, Nomura, Jinshang and other CNC core machines, which have many advantages in the field of precision machining of shaft parts. Because of its special structure, CNC core machines can be effective when processing long shaft products It maintains the accuracy and concentricity of the product, and can also achieve side milling and section milling in one-time clamping, which is an advantage that conventional CNC lathes do not have.