Compound machining to improve machining efficiency

2022-05-20
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Compound processing to improve processing efficiency

in terms of improving processing efficiency, reducing processing procedures and carrying out compound processing are also very effective means to improve processing efficiency

reduce machining process

when I communicate with my peers in many manufacturing enterprises, I found that they usually pay more attention to the three elements of cutting (cutting speed, feed and cutting depth), but they don't pay enough attention to reducing machining process. In fact, reducing machining processes is often more effective than improving cutting parameters

for example, locating pin hole is the most common element in machining, which is encountered in many parts. I see that most factories use the technological process of drilling, reaming and reaming to complete the processing of this element. Because the diameter of some pin holes is not large, some users feel that the significance of using cemented carbide to improve the cutting speed is not very practical. They still use high-speed steel bit to drill, and then ream and ream. However, due to the poor rigidity of high-speed steel drill bit (the young's modulus of high-speed steel is only 1/3 of that of cemented carbide), it is particularly easy to produce hole out of roundness when drilling, so we have to add a reaming process to prevent the reaming from meeting the product quality requirements due to error reflection. The rigidity of cemented carbide is better, and now some structures that optimize the processing quality can often avoid the process of reaming

the above figure is the comparison of the roundness of their integral cemented carbide se bit and ordinary high-speed steel bit provided by Kenner. In this comparison, the roundness of high-speed steel bit is 20 μ m, while the roundness of Se bit as an integral cemented carbide bit is only 1/5 of the former. According to this comparison result, we can completely consider eliminating the reaming process. In some cases, it can even replace the reaming with low requirements (for example, when making the threaded bottom hole for extrusion tap)

nowadays, direct milling of hard materials is also an effective method to reduce processing procedures. During my service in Walter, I once conducted the test of direct milling of excellent materials in Shanghai Shenmo Mould Manufacturing Co., Ltd. of Shanghai Jiaotong University. I remember that time, the blade type finishing ball end milling cutter f2139 with a diameter of 16mm was used, and the ultra-fine particle cemented carbide coated with titanium nitride aluminide was used. The cutting depth was 0.7mm, the row spacing was 0.5mm, and the rotating speed was 7000r/min. The processed workpiece is steel that has been heat treated to 50HRC. The machining continued for about 1 hour and 20 minutes, and the predetermined target was successfully completed. The wear of the back flank of the blade was about 0.15mm, so it should be considered that the cutting can be continued

such hard material milling is equivalent to combining the rough machining before the traditional heat treatment with the semi finish machining after the heat treatment, which greatly saves a lot of time including positioning and clamping, and is also very helpful to improve the processing efficiency

compound hole machining tool

compound machining of forming milling cutter for rough machining of blade root

compound machining is another very effective means to improve the efficiency of machining in order to solve the above problems. Several processes are combined and completed in one process, at least reducing tool change and saving time. Sometimes even several processes are carried out at the same time, which saves more processing time. Step drill is the simplest and most common compound machining tool. Most small holes need to be chamfered at the orifice. The step drill starts chamfering at the last stage of drilling, and the chamfering is also completed when the drilling is completed

on the right is Walter's compound hole machining tool. It can finish the three half finish machining and corresponding chamfering of three holes with different diameters in one feed: the part of the blade visible from the front can complete the semi finish boring of two diameter sections with small diameter and large diameter and the chamfering of medium diameter; The upper part can only be seen that the part of the back surface of the blade has completed the semi fine boring and the chamfering of small diameter and large diameter until the oil cylinder is completely back

unparalleled quality experience. The figure at the bottom right is Walter's forming milling cutter for rough machining of steam turbine blade root. If you do not use the forming tool and use the general ball end milling cutter to process, the processing time will be very long and the efficiency will be very low. The forming milling cutter can finish the rough machining of the profile at one time, and the machining efficiency is naturally much higher

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