Study On Chip Separation Characteristics In Multidimensional Ultrasonic Machining Ti3Al Intermetallic Compounds

Ti3Al intermetallic compound material for its better specific strength and creep performance than other titanium alloys and superalloys,is being widely used in high-precision fields such as national defense and aerospace.However,its inherent brittleness and high cutting resistance make it difficult to guarantee the processing quality.The ultrasonic vibration cutting technology is widely used in the processing of hard-to-cut material such as glass,ceramics,nickel-based alloys,high-temperature alloys and titanium alloys.It has the advantages of reducing cutting force and improving processing quality.It combines ultrasonic processing with traditional cutting.The combination of machining changes the formation and deformation of chips during the machining process,especially the influence of the multi-dimensional ultrasonic vibration milling(MUVM)process on the chip formation mechanism during the machining process help to promote the application of ultrasonic machining in Ti3Al intermetallic compounds and the promotion of similar materials.The main research contents and conclusions of this paper are as follows:(1)The chip forming mechanism of ultrasonic vibration cutting was obtained.According to the dynamic model of ultrasonic vibration cutting,the effect of the separation and non-separation characteristics of the chips in ultrasonic vibration cutting is systematically explained.The trajectory of one cutter tip of the milling cutter in the process of MUVM was deduced,and the chip separation and non-separation characteristics of the MUVM were analyzed.(2)A multi-dimensional ultrasonic vibro-acoustic system was built,and the half-wavelength theory and apparent elasticity theory were used to design the non-uniform medium symmetric structure acoustic vibration horn and the non-uniform medium asymmetric structure two-dimensional orthogonal acoustic vibration platform.The vibration characteristics of the platform were tested,and it was found that the actual processing platform was basically consistent with the theoretical analysis results.(3)Deform-3D software was applied to perform cutting simulation of traditional milling,two-dimensional and three-dimensional vibration.It was found that when the depth of cut was 0.1mm,the ultrasonic amplitude was 4μm,and the frequency was35000Hz.The F_x,F_y,and F_zof the two-dimensional ultrasonic vibration of the workpiece were reduced to different degrees compared with traditional processing,and the F_zof the three-dimensional ultrasonic vibration was smaller than the two-dimensional vibration of the workpiece,and of traditional processing as well.The surface morphology of three-dimensional ultrasonic vibration milling was better than that of two-dimensional and traditional machining,reflecting the superiority of MUVM processing Ti3Al intermetallic compound compared with ordinary milling.(4)The Ti3Al intermetallic compound was subjected to a MUVM test,and its cutting force was analyzed.It was found that the force trend in traditional cutting and multi-dimensional ultrasonic cutting was similar.When the spindle speed was1700r/min,the four-dimensional cutting force was less than the result of three-dimensional ultrasonic vibration machining in the three-direction of x,y and z.When the speed coefficient was less than 1.1,the x,y,z three-direction milling force increased,and vice versa.(5)The machined surface was inspected offline,and it was found that compared with the surface in traditional milling,the one in MUVM had a"drain-like"microstructure for the speed coefficient K 1.475,and a"wheat-shaped"microstructure for the speed coefficient K 1.966.The formation of chips at this time showed non-separation characteristics.In four-dimensional ultrasonic milling,the"honeycomb-like"microstructure gradually increased as the speed coefficient K rose from 0.952 to 4.571.At this time,the cutting chips changed from separation characteristics to non-separation characteristics.Better surface quality and lower cutting force can be obtained by using MUVM technology to process Ti3Al intermetallic compounds.61 pictures,19 tables,73 references.