The customization technology of CNC machined parts has much in common with the processing technology of ordinary machine tools, but the processing rules of CNC machined parts are much more complicated than ordinary machine tools. Before CNC machining, programmers must have a rich knowledge base to program the movement process of the machine tool, the machining process of the parts, the tool shape, the cutting parameters and the tool path. Qualified programmers first become qualified technicians. Otherwise, the whole process of parts processing and accurate and reasonable parts processing cannot be fully considered.
The main content of the custom design of CNC machining parts: the selection of the custom process content of the CNC machining parts; the analysis of the CNC machining technology: the design of the CNC machining process route.
First, the selection of the content of the CNC machining process For a single part, not all machining processes are suitable for CNC machine tools, but usually only part of the machining content is suitable for CNC machining. This requires a detailed process analysis of the part drawing and selection of the content and process most suitable for CNC machining. When considering the choice, it is necessary to solve difficult problems in combination with the actual situation of the enterprise’s equipment, overcome the main problems, improve productivity, and give full play to the advantages of CNC machining.
1. When selecting content suitable for CNC machining, the following order can usually be considered:
(1) Priority must be given to the content that cannot be processed by ordinary machine tools.
(2) It is very important to choose products that are difficult to process and whose quality is difficult to guarantee.
(3) If the processing efficiency is low and the manual labor intensity of the workers is high, they can choose when the CNC machine tool still has the processing capacity.
2. Generally speaking, if the above-mentioned processing content is processed by numerical control, the parts that are not suitable for numerical control processing will be greatly improved in terms of product quality, production efficiency and comprehensive benefits. On the contrary, CNC machining is not recommended.
(1) The machine adjustment takes a long time. In order to place the first completed datum on the rough datum of the blank, special tools must be used to adjust the part.
(2) The processing parts are scattered, and it needs multiple installations to set the origin. At this time, the use of CNC machining is very troublesome and the effect is not obvious, and it can prepare for ordinary machine tool processing.
(3) According to specific manufacturing standards (such as contours processed by templates). Due to the difficulty of data access, it is easy to conflict with the inspection basis, which makes program design more difficult.
When selecting and determining processing content, factors such as production batches, production cycles, and internal process turnover rates must also be considered. In short, in order to achieve the goal of being as reasonable as possible, as fast as possible, as good as possible and in as many places as possible. It is necessary to prevent CNC machine tools from becoming ordinary machine tools.
Second, numerical control processing technology analysis The numerical control processing technical problems of the processed parts are very extensive. Based on programmability and convenience, some main content to be analyzed and discussed are presented below.
(1) The size must conform to the characteristics of CNC machining.
In CNC programming, the size and position of all points, lines and planes are based on the programming origin. Therefore, it is best to specify the coordinate size directly in the part drawing or use the same datum to specify the size as much as possible.
(2) The conditions of geometric features must be complete and accurate.
The programmer must fully understand the relationship between geometric feature parameters and each geometric feature that constitutes the contour of the part. All geometric elements of the part outline are defined in the automatic programming process, so the coordinates of each node are calculated in the manual programming process, so even if a certain point is unclear or uncertain, it cannot be programmed. However, during the design process, the part designer did not think well or was ignored, so the parameters were incomplete or unclear, such as arcs tangent to the straight line, intersection or separation. Therefore, when checking and analyzing the drawings, if we find problems, we must carefully consider and contact the designer in time.
(3) Reliability of positioning reference
In the customization of CNC machining parts, the machining process is usually very concentrated, and positioning with the same standard is very important. Therefore, it is usually necessary to set some auxiliary benchmarks or add some process bumps on the blank. In order to improve the dimensional stability of the parts, process bosses can be added to the floor and removed after processing.