Fundamental Research On The High Speed Grinding With Regular Abrasive Distribution Wheel

The high speed grinding refers to advanced technology in machining filed. It brought the traditional grinding speed to a revolutionary stage and subverted the view that the grinding sacrifice the efficiency to precision, however, the specificity of chip formation and advantages for high speed grinding are not recognized by demarcation between conventional grinding and high speed grinding which defined by the 50m/s or higher speed value. The bottleneck problems of high temperature and burn are not solve in high speed grinding of high strength and toughness difficult-to-machining material, the material removal rate is still not improved for grinding machining filed by taking advantage of the high speed grinding technology. Thus, in this paper, the chip formation of high speed grinding is intensive studied by the single-grain tests, based on this, the countermeasure advanced in this paper to break the bottleneck is that the process of high speed grinding is optimized by adopting the regular abrasive distribution grinding wheel. then the topography model of the regular abrasive grinding wheel and the grinding process models are set up, these models are to be perfect by analyzing the relationships among grinding speed, the maximum undeformed chip thickness, and grinding force, specific energy, grinding temperature in the high speed grinding experiments. The optimization for high speed grinding of titanium alloy and superalloy is finished. At last, the speed effect and size effect for the high speed grinding process are explained by difficult-to-machining material constitutive relation. Following fundamental investigations are carried out.(1)During high speed grinding, the chip of single grain formed at a very high strain rate, so the effects of thermal-mechanical coupling are considered. Therefore, according to the limitations of traditional method of single-grain scratching tests, this paper innovatively presented the two single-grain grinding test method, the “single step method” and “two steps method”. The chip formation process were observed and the critical thickness of chip formation were quantificationally analyzed for the first time, and the characteristic of shear deformation of serrated grinding chips and swelling rate were intensively analyzed. The results indicate that the mechanism of chip formation change by increasing in grinding speed and maximum undeformed chip thickness.(2)This paper made the research on the traditional modeling and analysis of grinding process and pointed out their application limitation. then an research ideas was advanced in this paper, firstly, the high speed grinding process model based on the regular abrasive distribution grinding wheel were set up, and then the relationship were built up taking the grinding speed and maximum undeformed chip thickness as ligament, finally the optimized grinding parameters was achieved. In this paper the characteristic elements of regular abrasive distribution grinding wheel were modeled, and the related elements models for grinding process such as the number of active grains, maximum undeformed chip model, grinding force, average heat flux in grinding zone etc. were set up. At last the high speed grinding application system based on the regular abrasive distribution grinding wheels was established.(3)Under the guidance of research thinking which is that the “grinding process optimization based on the regular abrasive distribution grinding wheel”, the high speed grinding experiments for TC4 titanium alloy and GH4169 superalloy were systemically carried out by using the regular abrasive distribution grinding constant, the grinding force and specific energy still keep constant with an increasing in grinding speed. The specific energy decreases with enhancing the maximum undeformed chip thickness. the regular abrasive distribution give the grinding wheel superiority in grinding force and grinding temperature reduction to brazed abrasive wheel and ceramic bond wheel. These results indicate that the high speed grinding has great advantage and provide direction to optimize the high speed grinding parameters of TC4 titanium alloy and GH4169 superalloy. This direction is that based on the regular abrasive distribution grinding wheel, under the condition of keeping the speed ration or the maximum undeformed chip constant and non-burn in grinding process, the material removal ratio can be improved when increasing grinding speed, which may be encouraging.(4)According to the material constitutive relation, the size effect and speed effect on the critical thickness of chip formation, specific grinding force, grinding force, specific energy and grinding temperature were analyzed in grinding with single-grain tests and grinding with wheel. For the first time, the section of grinding process model based on the material constitutive relation was set up. In this paper, It is proposed that the speed effect and size effect on grinding force, specific energy and grinding temperature were explained resulting from the factors as strain hardening, strain rate strengthening,thermal softening and also the micro-defects of the contacting region material. The analysis equations of specific grinding force, grinding force, specific energy were deduced on account of the material constitutive relation and grinding process model. The method and formula of staged moving heat source plane were systematically established through analyzing the heat generation and heat transfer in high speed grinding zone. The deductive thinking and results are considered to successfully make clear the high speed grinding mechanism which explained by impact dynamics and metal processing theories.