CNC machining process flow
Processing process planning refers to the entire process, which cannot be judged by the nature of a process and the processing of a certain surface. For example, some positioning datum surface, in the semi-finishing stage or even in the rough processing stage need to be processed very accurately. Sometimes in order to avoid dimensional chain conversion, semi-finishing of certain secondary surfaces can also be arranged during the finishing stage.
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When the processing method and processing stage of the surface of the part are determined, the processing of each surface in the same processing stage can be combined into several work steps.
1. The method of dividing the processing process
Parts processed on CNC machine tools are generally divided into processes according to the principle of process concentration, and the methods of division are as follows:
1) Divided according to the tool used
With the same tool to complete the process as a process, this division method is suitable for the workpiece to be machined more surface situation. Machining centers are often completed by this method.
2) Divided by the number of workpiece installations
The process that the parts can be completed at one time is taken as a process. This method is suitable for parts with few processing contents, and under the premise of ensuring the processing quality of parts, the whole processing content is completed at one time.
3) Divided by rough finishing
The part of the process completed in roughing is regarded as one process, and the part of the process completed in finishing is regarded as another process. This division method is suitable for parts that have strength and hardness requirements, need heat treatment or parts with high accuracy requirements, need to effectively remove internal stress, and parts with large deformation after processing, need to be divided according to rough and finish processing stages.
4) According to the processing parts, the part of the process that completes the same shape surface is divided as a process.
For parts with more and more complex processing surfaces, the order of CNC processing, heat treatment and auxiliary processes should be reasonably arranged, and the connection problem between processes should be solved. 2. Parts are composed of multiple surfaces, which have their own accuracy requirements, and there are corresponding accuracy requirements between the surfaces. In order to meet the design accuracy requirements of parts, the processing sequence arrangement should follow certain principles.
1) The principle of first rough and then fine
The processing sequence of each surface is carried out in accordance with the order of rough machining, semi-finishing machining, finishing and finishing machining, with the purpose of gradually improving the precision and surface quality of the machined surface of the parts. If all the surfaces of the parts are processed by CNC machine tools, the process arrangement is generally carried out in the order of roughing, semi-finishing and finishing, that is, semi-finishing and finishing are carried out after the roughing is complete. Roughing can quickly remove most of the processing allowance, and then finish each surface in turn, which can improve production efficiency, but also to ensure the processing accuracy and surface roughness of the parts. The method is suitable for machining surfaces with high position accuracy. This is not absolute, such as for some machining surfaces with high dimensional accuracy requirements, taking into account the stiffness, deformation and dimensional accuracy of the parts, it can also be considered that these machining surfaces are completed in the order of rough machining, semi-finishing and finishing. For the machining surface with high precision requirements, between the rough and finish machining processes, the parts are best shelved for a period of time, so that the surface stress of the parts after rough machining is completely released, and the degree of stress and deformation of the surface of the parts is reduced, which is conducive to improving the processing accuracy of the parts.
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