Selection of cutting tools and cutting parameters

Selection of cutting tools and cutting parameters in NC milling

with the development of national economy, China's machinery processing industry has also achieved unprecedented development. The processing tools and processing technology have changed significantly, and the processing level has also been significantly improved. Among them, numerical control milling is a commonly used technology in machining in our country at present. In the process of machining with mechanical equipment such as levers, it is necessary to use numerical control technology to control the machining program and select the machining tools and cutting parameters. If the tool and cutting parameters are not selected properly, the consequences will be troublesome and the machining effect will be greatly affected

1. Selection of cutting tools in NC milling

1.1 types of machining tools

the application of NC technology in the machining industry has greatly improved the efficiency of machining, but it also puts forward higher requirements for machining tools. Compared with traditional machine tool processing, NC processing pursues processing speed and processing quality, and automatically adjusts the position of the tool through computer control. To achieve these purposes, we must ensure the wear resistance, rotatability and rigidity of the processing tool, and the sharpness of the blade. Only in this way can we achieve the purpose of long-time uninterrupted rapid machining in NC milling. At present, there are mainly two kinds of tools used in NC Milling: milling tools and hole machining tools. According to different structures, it can be divided into special type, integral type and mosaic type

1.2 selection of machining tools

in NC milling, the selection of machining tools must follow the following principles: first, ensure the machining accuracy. To ensure the machining accuracy, it is necessary to ensure that the cutting tools have strong durability and sharpness, as well as good chip breaking ability. The list of top 50 leading enterprises of new materials of the year must be released; Second, ensure the strength of processing. In NC milling, the processing intensity is higher, which requires that the processing tool must meet the processing intensity. To meet the processing intensity, the processing tool needs to meet two conditions: first, the processing intensity, processing direction and blade position of the tool can be adjusted by computer; Second, meet the needs of long-time and large-scale cutting. Therefore, the above factors must be taken into account when selecting the machining tool. The specific selection work is completed in the human-computer interaction interface under the NC program. Workers need to select tools according to the quality of the machine tool, processing performance, working order, etc., and also consider the nature and quantity of processing materials. It is necessary to ensure that the machining tools conform to the specifications of the machine tool. To select a good machining tool, you also need to select a suitable handle. Generally, the length of the handle should not be too long, otherwise it will affect the normal operation of the machine tool. Of course, in the actual processing process, in addition to requiring the cutter to conform to the specifications of the machine tool, it is also required that the material shape processed by the cutter should be consistent with the required processing shape. For example, when processing spherical and curved materials, you need to choose a ball head cutter; Special keyway tools need to be selected for machining closed keyways

2. Selection and determination of cutting parameters

the cutting parameters in NC milling mainly change according to the change of machining method. In the selection of cutting parameters, three factors need to be considered: cutting depth, feed rate and speed. Generally speaking, during rough machining, the processing speed should be accelerated as much as possible to maximize the output in the shortest time, so the amount of cutting in this process is large; When finishing, to ensure the precision of processing and improve the quality of processed products, we need to choose a smaller cutting amount

2.1 depth of cutting

due to the different types of machine tools and processed materials, the depth of cutting is also different. When selecting the cutting depth, the staff must choose the cutting depth according to the actual situation, such as the type of machine tool, processing materials, processing tools, etc. Generally speaking, in rough machining, we should try to set the cutting depth deeper and cut off the excess material at one time. Of course, its premise is that the rigidity of the tool meets the requirements, otherwise there may be continuous cutting due to insufficient rigidity of the tool or too thick material. In the cutting process, the blade should be facing inward to avoid the contact between the blade and the metal of the machine tool. When the rigidity of the tool is not enough, the material is thick, and the impact load is relatively large, it is necessary to set the cutting depth shallower, improve the success rate of cutting, and reduce the damage to the tool in the cutting process. At the same time, we need to constantly adjust the cutting depth according to the change of machining allowance. The less the allowance is, the less the cutting depth will be. Only in this way can we avoid the waste of resources and improve the quality and efficiency of machining. Generally, the cutting depth of finish machining is between 0.05 and 0.8 mm, and the cutting depth of semi finish machining is between 1 and 3 mm. The staff must think that President Xi's visit should set the cutting depth within the scope and in combination with the actual situation

2.2 cutting speed

generally speaking, the larger the diameter of the milling cutter, the faster the cutting speed under the condition of constant rotating speed. However, if the cutting speed is faster, the tool will produce higher heat and speed up the wear of the tool; Moreover, the deeper the cutting depth is, the slower the cutting speed is. Therefore, the staff must reasonably set the cutting speed, not blindly seek speed, speed up the wear of tools and reduce the quality of processing. In addition, the staff also need to consider different situations. For example, at the corner of the material, the processing speed should be reduced, and after the corner, the processing speed can be accelerated; When machining curved materials, the influence of arc radius on machining speed should be considered. Generally, the actual cutting speed of outer arc is small, and that of inner arc is large. The staff should choose the cutting speed according to the situation

2.3 cutting feed rate

the main influencing factors of the feed rate include the rigidity of the tool, the strength of processing, the quality of materials, etc. In rough machining, the rigidity and processing strength of the tool are mainly considered. If the rigidity of the tool is large, you can choose a larger feed rate. If the rigidity is small, you can choose a smaller feed rate. When finishing, consider the quality of materials, such as surface roughness and other factors. If the roughness value of the surface is large, you can choose a larger feed rate. However, generally, the range of feed rate during finishing is between 50 and 100mm/min, which cannot be too large or too small

3. Conclusion

in short, in NC milling, to improve the quality of processing and ensure the efficiency of processing, the choice of cutting tools and cutting parameters is particularly important. In the selection of cutting tools, two factors, machining accuracy and machining strength, are mainly considered. According to these two factors, the cutting tools that can be automatically adjusted and can be cut for a long time are selected; The selection and determination of cutting parameters need to consider three factors: cutting depth, cutting speed and cutting feed. Only in this way can we reasonably select cutting tools, determine cutting parameters, and realize the safe and effective operation of machine tools