Compared with traditional machine tools in processing, CNC machine tools have great advantages in technology and are the product of the development of modern science and technology. At present, CNC machining centers and CNC lathes continue to use traditional machining processes in many aspects, integrating traditional machining processes with the machining characteristics of CNC machine tools, so that the advantages of CNC machine tools can be brought into play. However, it is unscientific to use traditional machine tool processing technology in this way. Technicians should evaluate new processing technology according to the characteristics of NC processing, so that NC processing technology can give full play to its advantages.
1. The NC processing technology is relatively complex
When using the NC machining process, it is necessary to fully consider the positioning datum, processability and clamping method of the parts, as well as the process route, tool selection, process parameters and cutting methods. These can be simplified in the traditional machine tool processing. Therefore, the NC machining process is much more complex in actual use, and there are many factors affected. In the process of use, the NC programming must be scientifically and reasonably analyzed, and the analysis must be comprehensive.
For the same machining task, when using NC machining, there can be different process schemes, which is one of its main features and is incomparable to traditional machining processes.
2. Tool selection
Because the methods and processes of NC machining and traditional machining are very different, the selection of tools is also very different. High speed cutting is used in the process of NC machining, while speed cutting is used in traditional machining, which has great advantages in this regard. High speed cutting has greatly improved the processing quality and efficiency, reduced cutting deformation, and improved the processing cycle. Therefore, high-speed cutting should be appropriately increased in processing and manufacturing. CNC lathe processing is targeted at Tihao machinery, and the quality is guaranteed. At present, dry cutting is still widely used. In this way, only a small amount of cutting fluid or no cutting fluid is added, but the tool should have ultra-high heat resistance. Compared with traditional machining, NC machining has higher requirements for cutting tools. In addition, the position of the tool manufacturer has changed, which has greatly changed the role and position of the tool industry: in the past, only tools were produced and supplied separately, but now, not only tools are produced, but also cutting processes are developed and innovated, and corresponding supporting products and technologies are produced; From the original tool supplier to the important partner of the enterprise to improve efficiency and quality in production and manufacturing.
3. Selection of Clamps and Fixtures
When NC machining, there are two requirements for the fixture: first, the coordinate direction of the fixture and the machine tool should be fixed; Secondly, coordinate the dimension relationship between the machine coordinate system and the parts. When selecting the fixture, the CNC machining center shall determine the position and installation requirements according to the datum hole and groove of the workbench, so as to ensure the dimensional relationship between the machine coordinate system and the parts, which is one of the important differences from the traditional machine tool processing. If you want to learn UG NC programming, you can add QQ group: 565120797 to get programming information.
There are two main steps in clamping, namely clamping and positioning. When clamping the traditional machine tool, the number of clamping times increases due to the limitation of the machine tool capacity. When clamping the CNC machine tool, multiple surfaces can be processed at one time, thus reducing the clamping error. In the process of clamping, special fixtures are used to facilitate positioning and clamping, but the cost is very high. If the number of pieces to be processed is large, the cost shared in the fixture cannot be ignored. Therefore, attention should be paid to this when designing and using special fixtures. CNC machining can be debugged through instruments to meet the requirements of positioning standards. This process does not require special fixtures, and only ordinary pressing elements can complete the clamping, thus greatly reducing the cost.
4. Comparison of tool paths
When determining the tool path of an ordinary machine tool, the workers themselves need to control and grasp it. In numerical control processing, the tool path has been determined at the time of engineering preparation.
5. Comparison of processing methods
CNC machine tools have a great feature. For some traditional machine tools, some processing methods need to be used with caution, which makes them usable. Cantilever boring in traditional machining and support boring formed by tailstock guidance are replaced by turning boring in CNC machine tools and different forms of fixed cycle boring. The empty tool method, filling method, trimming method and other processes used in traditional machining are replaced by various back boring methods, arc interpolation methods and CNC trimming methods. At present, as a new machining process, the newly developed hard cutting can not only improve the working efficiency, but also greatly reduce the cost input, which makes the traditional grinding process face new challenges. The process of replacing grinding with cutting will be the development trend of modern manufacturing. Compared with wet cutting, dry cutting, a green manufacturing process, also has many advantages, but it still has disadvantages. The low durability of the tool and the increase of cutting force cause serious deformation, which cannot guarantee the processing quality of the workpiece. However, through the analysis of the influencing factors and characteristics of dry cutting, the advantages of this cutting method are relatively large.
6. Comparison of cutting parameters
In the traditional processing, the control and manipulation of the machine tool are completed by the staff relying on their work experience, which is relatively conservative in terms of safety and control ability. Especially when operating curved surfaces and curves, it is easy to make mistakes. In order to reduce the scrap rate, the cutting amount is increased. The NC machine tool is controlled by the control system when processing and manufacturing. No matter what shape or surface is encountered, it can be well controlled. The work of the tool on the working surface is flexible and automatic without interruption. During the processing, the program will set a reasonable value for the cutting amount, which greatly improves the processing efficiency. This is compared with the traditional machine tool processing, It has great advantages.
At present, when high-speed machining is adopted for rough machining, the combination of high cutting speed, high feed rate and small cutting amount is adopted. In this process, it is necessary to increase the number of cuts, but it is very valuable to comprehensively compare the processing efficiency, durability and system stiffness. In addition, there is another kind of high-speed machining process in which the speed is automatically optimized. The cutting speed is accelerated at the position with small cutting amount, and the cutting speed is increased at the position with large machining allowance, so that the processing time is shortened, the processing efficiency is improved, the tool damage rate is reduced, the durability is improved, and the processing quality is improved. After the F value is optimized, the cutting speed can change constantly according to the change of the allowance, which is impossible to achieve in the traditional machine tool processing.
7. Comparison of flexibility
In the traditional machine tools, the flexibility of general machine tools is very good, but the machining efficiency is very low; The special machine tool has high processing efficiency, but it does not have a high part application function. Due to its poor flexibility and high stiffness, it is difficult to adapt to the continuous modification of products in the market, making the competitiveness weak. For CNC machine tools, as long as the program is changed, new parts can be processed. It is flexible, automatic and efficient, and can well adapt to the fierce market competition.
8. Quality comparison
When using numerical control processing, the degree of automation is very high, and special attention should be paid to quality and safety. Before the process is put into production, the processing process should be tested. Only when it meets the requirements of all aspects of production can it be put into practical production and application. In traditional processing, the process documents can be put into production after being prepared, as the guidance of the production line, without the need for the above complex process.
To sum up, the basic guarantee of the NC processing technology is the traditional processing technology, which is based on the traditional technology to improve the NC processing technology. Although there is a certain degree of progressiveness in technology, it still has its own shortcomings. The advantages and disadvantages of the two processing technologies are analyzed by comparing them. The advantages and disadvantages of the two processing technologies should be correctly treated, and they should be reasonably arranged and used to improve production efficiency.
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