1. Process design characteristics of CNC machining

The process design using CNC machining has the characteristics of simple processing procedures and liberating the labor force of boring work. It improves the weakness of the traditional machine tool process with many processes and high labor intensity. In this way, the CNC machining process design has formed its own unique characteristics. Normally speaking, the content of CNC machining is more than that of traditional machine tool processing. The content of CNC machining is very precise, and the process design work is very logical. The efficiency of CNC machining is very high. Parts can complete multiple work items in a single operation. If these tasks are replaced with traditional processes, they require multiple steps to do well. Therefore, CNC machining has the characteristics of high work efficiency. Several steps in the traditional processing work are condensed into fewer work steps in the CNC machining process, which greatly reduces the number of professional tools required for parts processing, and the process and time required for parts processing are also saved, thereby greatly improving the yield and production efficiency of the processed products. In addition, in the ordinary machine tool processing, many specific process problems, such as how to classify and arrange the order of various processes during processing, the shape and size of the tools used in each process, how to cut, how much to cut, etc., are solved by the skilled skills slowly exercised by the staff according to their years of work experience and habits. Under normal circumstances, the process design of traditional processing does not require processing personnel to make too much planning when designing the process flow, and the actual work can be done well. In CNC machining, every actual process problem must be taken into account, and every detail must be programmed into the completely correct processing instructions when the program is edited, and the result will be very fine, which is the biggest feature of CNC machining.

2. Process design method of CNC machining

The task of process design is to clarify what parts of the part need CNC machining, what process it goes through, how to determine the sequence of these processes, and so on. Usually the work steps of parts processing are determined during CNC machining in the following ways: according to the working tools used. In order to reduce the number of switching work tools and save time, the method of combining the same work tools can be used to determine the work steps. All steps using the same work tool in one process are first concentrated, and after the unification is completed, the second work tool is used to carry out all the steps to be processed by the work tool, and so on. Planar hole parts generally use point, linear control CNC machine tools to process, and when formulating the processing steps, focus on controlling the processing accuracy, yield and processing time. Rotating body parts are usually machined using CNC lathes or grinding machines. When processing on lathes, the finished products are generally processed with redundancy and rough machining methods are used. Low-strength machining tools are used on CNC lathes to process small grooves frequently, so it is suitable for diagonal feeding, generally do not break the edge. Flat contour parts are generally machined using CNC machine tools. The method should focus on controlling the direction of cutting in and cutting out. When CNC machine tools using straight and circular interpolation functions process the curve contour of irregular parts, they must use the shortest straight or circular segment to approximate the part contour infinitely, so that the error of the part is the best solution to minimize the number of straight segments or arc segments processed on the basis of qualification [2]. Three-dimensional contour parts: When parts of certain shapes are processed, the strength of the parts is poor due to many problems such as the shape and surface quality of the parts. The interpolation method of the machine tool can solve this problem. When machining the straight-grained surface of aircraft girder, if the machining machine tool is three-axis linkage, only the less efficient ball milling cutter can be used; If the machine is four-axis linked, cylindrical milling cutters with higher efficiency than ball nose milling cutters can be used for milling.

3. Process design process of CNC machining

The general process of CNC machining should go through reading parts, process analysis, formulating processes, CNC programming, and program transmission. Before CNC machining, the machining design drawings of the parts should be drawn. When machining parts on CNC machine tools, the structure, material, geometry, size and accuracy requirements of the parts should be analyzed according to the previously drawn part drawings, and the analysis results should be used as the basis for determining the CNC machining process of the parts. To determine the CNC machining process, we must first understand the content and principles of CNC machining of parts in detail; After that, design the processing process, select the tools required for machine tools and processing parts, determine the processing position and clamping of parts, determine the steps and sequence of work in CNC machining, and determine the use method and cutting size of specific working tools in each working step; It is also necessary to fill in the process documents, processing procedures and program verification of CNC machining. Through the summary of actual operation experience, there are still many defects in simply operating the machined parts according to the previously set CNC machining program. Because the human work may not be clear enough about the specific steps and principles of the program, the original understanding of the programmer is not very thorough, usually need the programmer to guide the processing personnel on the spot when the parts are processed, this situation can barely work normally for the processing of a small number of parts, but for the production of long time and large quantities, many problems will arise. Therefore, the role of programmers in properly supplementing and explaining the more complex and incomprehensible parts of the CNC machining program cannot be underestimated, especially for those CNC machining programs that require long-term and high-volume production of parts.