Experimental Investigation On High Speed Deep Grinding Characteristics Of The Nano-cemented Carbides

Due to their high hardness,high toughnes, high bending strength, high wearresistance,nano-cemented carbides have been widely used in industry. Although thepreeminent mechanical properties of nano-cemented carbides facilitate their wideapplications, they also create a challenge in machining.There are some disadvantagesin conventional grinding like high grinding force, high grinding temperature, highwheel wear. This thesis project thus aimed at developing a high speed deep grinding(HSDG) technology for efficiency machining of nano-cemented carbides andinvestigating the associated removal mechanisms. The research contents mainlyinclude:(1) The preparation technologies, material properties and application status ofnano-cemented carbides were introduced；and the characteristic of high speed deepgrinding technology and its development, research status and mechanisms wasdescribe. And then the general structure and contents of this dissertation was brieflyintroduced.(2) Based on the existing research about high speed deep grinding of brittlematerials, an systemic investigation was undertaken in high speed deep grinding onnano-cemented carbides in this article.The influence of the parameters on thegrinding force, specific grinding energy and surface integrity was investigated bychanging the process parameters,and then the material removal mechanism wasanalyzed.(3) The grinding characteristics of cemented carbides with various grain sizeswas analysed，and the influence mechanism of grain size on grinding force wasinvestigated.(4) Wheel speed, feed rate and grinding depth are taken as design variables,based on orthogonal experimental design and response surface methodology,a highspeed grinding surface roughness prediction model of nano-cemented carbides wasmade, and optimized design of grinding parameters was made based on this model.The results indicated that the application of high speed deep grinding onnano-cemented carbides can not only improve the machining efficiency，but alsoobtain a better surface finish. The increasing of wheel speed,and the decreasing offeed rates and depths of cut will lead to the decreasing of maximum chip thickness,grinding force, improvement of surface quality. A better surfacefinish,decreased grinding force and specific grinding energy are obtained on theworkpiece with a smaller grain size， the nano-cemented carbide’s removalmechanisms are more likely to be brittle. The surface roughness prediction model canpredict surface roughness accurately, and the optimal design of the process parametersis completed based on the response surface model and Non-dominated Sorting GeneticAlgorithm (NSGA-П)， which can be a reference for the selection of processparameters in industry.