The Research On Electrochemical Grinding Process For Titanium Alloys

With the rapid development of the modern industry, titanium alloys are more and more favored by industry of aviation, aerospace, medicine, oil, chemical and so on due to their high strength ratio, high temperature resistance as well as good corrosion resistance. However, as a result of all these good characteristics, titanium alloys are very difficult to be machined by traditional machining method. For example by traditional grinding, because of high grinding force, high grinding temperature and also high wear of grinding wheel, the grinding efficiency is very low. For electrolytic machining of titanium alloys, although the processing efficiency is high, but the processing stability is very low and the surface quality while processing is difficult to control, and it is prone to cause the phenomenon of stray current corrosion and hydrogen embrittlement. In consideration of high chemical activation of titanium alloys which are easy to generate a dense layer of passivation film quickly in air whose hardness is far less than the base metal of titanium alloys and easy to be removed by grinding, the electrochemical grinding(ECG) is proposed as a composite processing method. By process of electrochemical grinding, it can not only achieve high efficiency, but also to ensure the quality of surface, because more than 90% of the titanium alloys material is removed by electrolysis and only less than 10% of the material is removed by grinding process, therefore both the processing efficiency and surface quality can be improved greatly.In this paper, on the basis of fundamental experiment research on electrochemical grinding for titanium alloys, deep research on electrochemical grinding process of titanium alloys is carried out. Firstly, the research background, the basic theory of electrolytic machining as well as foreign and domestic research status of electrochemical grinding were introduced. Secondly, this article describes the basic theory of electrochemical grinding, the main parameters of electrochemical grinding machine and main measuring instruments as well as the preparation method of sample work pieces before experiment. Then the anodic polarization curves of titanium alloys TC18 in different electrolyte concentrations as well as in different flow rate of electrolyte are measured by three-electrodes system and constant potential rectifier as a basis of how to choose the level of electrolyte concentrations. And according to the results of single factor experiments on other research, reasonable levels of experimental factors for orthogonal experiment such as voltage, electrolytic solution concentration, feed rate and depth of cutting are decided. Taking into account of interaction effect of each of these factors, orthogonal table L27(313) is decided finally. According to the results of orthogonal experiments, analysis from 3 aspects of removal rate, surface roughness and composite indicator of both removal rate and surface roughness is carried out separately. Three optimized parameter groups are decided according to different evaluation target. Finally, by doing comparative experiments, comparative analysis of different technology feature from 4 aspects of removal rate, surface roughness, grinding pressure and surface residual stress are carried out between electrochemical grinding and mechanical grinding of titanium alloys TC18 is carried out.