Application analysis of the hottest superhard tool

2022-07-26
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Analysis on the application of superhard tools in hard turning

the blade structure and geometric parameters of superhard tools the reasonable determination of blade shape and geometric parameters is very important to give full play to the cutting performance of tools. In terms of tool strength, the tool tip strengths of various blade shapes from high to low are: round, 100 ° diamond, square, 80 ° diamond, triangle, 55 ° diamond and 35 ° diamond

after the blade material is selected, the blade shape with the highest strength should be selected. For hard turning blades, the radius of the tool tip arc should also be as large as possible. For rough machining with circular and large tool tip arc radius blades, the radius of the tool tip arc during finish machining is about 0.8? M or so. Hardened steel chips are red and soft ribbons, which are brittle, easy to break and non cohesive. Hardened steel has high cutting surface quality and generally does not produce chip buildup. However, the cutting force is large, especially the radial cutting force is larger than the main cutting force. Therefore, the tool should adopt a negative rake angle (go ≥ -5 °) and a large rake angle (ao=10 ° ~15 °). The main deflection angle depends on the rigidity of the machine tool and is generally 45 ° ~60 ° to reduce the chatter of the workpiece and tool. The selection of cutting parameters for superhard cutting tools and the requirements for the process system the higher the hardness of the workpiece material, the smaller the cutting speed should be. The suitable cutting speed range for hard turning finishing with superhard tools is 80 ~ 200m/min, and the common range is 10 ~ 150m/min; Large cutting depth or strong intermittent cutting of high hardness materials shall be adopted, and the cutting speed shall be kept at 80 ~ 100m/min. Generally, the cutting depth is 0.1 ~ 0.3mm. For the workpiece with low surface roughness, a small cutting depth can be selected, but it should not be too small, and it should be appropriate. Generally, the feed rate can be selected between 0.05 ~ 0.25mm/r, and the specific value depends on the surface roughness value and productivity requirements. When the surface roughness ra=0.3 ~ 0.4? M, it is much more economical to use superhard tools for hard turning than for grinding

requirements for the process system: in addition to selecting reasonable tools, there are no special requirements for the lathe or turning center to use superhard tools for hard turning. If the rigidity of the lathe or turning center is sufficient and the required accuracy and surface roughness can be obtained when machining soft workpieces, it can be used for hard cutting. In order to ensure the stability and continuity of turning operation, the common method is to use rigid clamping device and medium rake tool. If the positioning, support and rotation of the workpiece can be kept stable under the action of cutting force, the existing equipment can use superhard tools for hard turning. Application of superhard cutting tools in hard turning superhard cutting tools are used for hard turning. After more than ten years of development, popularization and application, this technology has achieved great economic and social benefits. The following takes roll processing and other industries as examples to illustrate the promotion and application of superhard cutting tools in production

roll processing industry many large domestic roll enterprises have used superhard cutters to carry out rough turning, rough turning and finish turning of chilled cast iron, hardened steel and other rolls, and have achieved good benefits. 7 on average, the processing efficiency is increased by 2 ~ 6 times, and the processing man hours and power are saved by 50% ~ 80%. For example, when rough turning and semi-fine turning of chilled cast iron rolls with hardness of hs60 ~ 80 are carried out by the roll plant of Wuhan Iron and steel company, the cutting speed is increased by three times. One roll per car saves more than 400 yuan in power and man hour costs, and nearly 100 yuan in tool costs. Great economic benefits have been achieved. For example, when our school turns 86CrMoV7 hardened steel rolls of hrc58 ~ 63 with fd22 cermet cutter (vc=60m/min, f=0.2mm/r, ap=0.8mm), the single edge continuous cutting roll path reaches 1. New materials are widely used in emerging fields such as new energy vehicles, wearable equipment, aerospace and ordnance industry for 5000m (the maximum width of the tool face wear belt behind the tool tip is vbmax=0.2mm), meeting the requirements of replacing grinding with turning. In the industrial pump processing industry, 70% ~ 80% of domestic slurry pump manufacturers have adopted superhard cutters

slurry pump is widely used in mining, electric power and other industries. It is a product urgently needed at home and abroad. Its sheath and guard plate are cr15mo3 high hard iron castings of HRC63 ~ 67. In the past, it was difficult to turn this material with various cutters, So only "said zhengdaqing, senior vice president of BASF Greater China: "BASF is eager to contribute to the soil protection in Xinjiang and the whole country, so it has to adopt the process of rough machining after annealing and softening, and then quenching. After using superhard cutting tools, it has successfully realized one-time hardening, eliminating the two processes of annealing and quenching, and saving a lot of man hours and electricity.

the processing of crankshaft, camshaft, transmission shaft, cutting tools and measuring tools in the automobile and tractor industries In the process of machining and equipment maintenance, we often encounter the processing problems of hardened workpieces. For example, a locomotive and rolling stock factory in China needs to process the bearing inner ring during equipment maintenance. The hardness of the bearing inner ring (material GCr15 steel) is HRC60, and the inner ring diameter is f285mm. The grinding process is adopted, and the grinding allowance is uneven, which takes 2H to grind; First, the super hard tool is used, and the menu prompt is processed into an inner ring in only 45min

conclusion: after years of research and exploration, China has made great progress in superhard tools, but superhard tools are not widely used in production. The main reasons are as follows: the production enterprises and operators do not know enough about the effect of hard turning with superhard tools, and it is generally believed that hard materials can only be ground; Think the tool cost is too high. The initial tool cost of hard turning is higher than that of ordinary cemented carbide tools that can withstand pressure up to 0.25MPa and high temperature of 260 ℃ (for example, PCBN is more than ten times more expensive than ordinary cemented carbide), but the cost allocated to each part is lower than that of grinding, and the benefit is much better than that of ordinary cemented carbide; The research on machining mechanism of superhard cutting tools is not enough; The standard of machining superhard cutting tools is not enough to guide the production practice. Therefore, in addition to the in-depth study on the machining mechanism of superhard tools, it is also necessary to strengthen the training of superhard tool machining knowledge, successful experience demonstration and strict operation specifications, so that this efficient and clean machining method can be more applied to production practice. (end)

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