Guo Fu Gao

Research on the characteristics of the cutting force in the vibration cutting of a particle-reinforced metal matrix composites SiCp/Al

Abstract In this paper, turning experiments on the machining of composites SiCp/Al with a polycrystal diamond (PCD) tool have been carried out. The cutting force characteristics in ultrasonic vibration turning compared with those in common turning were studied. Through single factor experiments and multiple factor orthogonal experiments, the influences of three cutting parameters, namely cutting velocity, amount of feed and cutting depth, on the cutting force were analyzed in detail. At the same time, according to the experimental data, an empirical equation for the main cutting force in ultrasonic vibration turning was deduced. The research results indicate that: (1) ultrasonic vibration turning possesses a much lower main cutting force than that in common turning when adopting smaller cutting parameters, but if using larger cutting parameters, the difference will become inconspicuous; (2) there are remarkable differences of cutting force–cutting velocity characteristics in ultrasonic vibration turning and those in common turning, mainly because a built-up edge does not emerge in ultrasonic turning, unlike common turning in the corresponding velocity range; (3) in ultrasonic vibration cutting, the influence of the cutting velocity on the cutting force is most obvious among three cutting parameters explored the influence of the feed being the smallest, thus adopting lower cutting velocity and larger cutting depth not only can reduce the cutting force effectively but also can ensure cutting efficiency; (4) the conclusions are useful in the precision and super-precision manufacturing of thin-wall pieces.

Research on the influence of the cutting conditions on the surface microstructure of ultra-thin wall parts in ultrasonic vibration cutting

Abstract In many fields of high-tech industry ultra-thin wall parts are employed. In this paper are reported experiments carried out to explore the surface microstructure of a camera’s guided draw-tube when applying an ultrasonic vibration cutting device to the traditional lathe. The influence rule of the cutting conditions on the surface roughness was put forward, which was drawn by comparing ultrasonic cutting with common cutting by use of a cemented carbide tool and a polycrystalline diamond (PCD) tool. The test results showed that the ultrasonic cutting performs better than the common cutting for the same conditions. According to the analysis of the test results, the surface characterization is influenced clearly by the rigidity of the acoustic system and the machine tool. Also it is dependent on the proper setting height of the tool tip, otherwise, dense regular low-frequency vibration ripples will be scraped on the ultrasonic machined surface, i.e., when the tool tip is set higher than the rotating center of the workpiece by three times the amplitude of ultrasonic vibration, the vibration ripples behave alight; on the other hand, they turn light and shade alternately when the tool tip is lower than the rotating center of the workpiece by three times the amplitude of ultrasonic vibration.

Study on Ultrasonic Vibration Drilling of Particulate Reinforced Aluminum Matrix Composites

Metal matrix composites（MMCs）is applied widely in recent years because of its excellent performances, but the machining is very difficult due to the rigidity of reinforced-phase in it, so, the application of MMCs is restricted much. In this paper the experiment of common and ultrasonic vibration drilling is performed to SiC particulate reinforced Al matrix composites （SiCp/Al）by use of carbide-alloy-twist-drill, and the surface roughness of hole is compared, furthermore, the wearing of twist drill and the feature of chips are analyzed by scanning electron microscope (SEM). From above, we can draw aconclusion that ultrasonic vibration drilling may meliorate the mechanism of drilling to some extent and it takes on much superiority that the common drilling is unmatched, so this method could provide a certain foundation for the posterior study and application.

Experimental Research on Surface Integrity of Ceramic Nanocomposites in Two-Dimensional Ultrasonic Vibration Grinding

The grain cutting trace of elliptical spiral in workpiece two-dimensional ultrasonic vibration grinding(WTDUVG) is defined, the reason of machining accuracy improvement by applying two-dimensional ultrasonic vibration is discussed. Adopting two-dimensional ultrasonic composite processing, the influences of grinding depth, worktable velocity, wheel granularity on the surface roughness of Al2O3/ZrO2 ceramic nanocomposites were described. Experimental results of AFM microstructure show that the material removal model in WTDUVG is dominated by ductile flow of material, some crystal refinement, the crush powder and grain pull-out are visible and there is almost no fracture. Furthermore, the surface roughness in WTDUVG with coarse grit is about 30 40% less than that in CG under identical grinding condition; the qualitative analysis of X-diffraction results indicated that the surface phases are composed of α-Al2O3, t-ZrO2 and small quality m-ZrO2, there are amorphous phase in the surface both with and without vibration grinding. M-zirconia phase transitions rule in vibration and conventional grinding was found. Under definitive grinding conditions, the material removal mechanism of inelastic deformation is the principal removal mechanism of Al2O3/ZrO2 ceramic nanocomposites, the grit size of diamond wheel and vibration grinding mode have important influence on material removal mechanism of ceramic nanocomposites.

Research on Micro-Mechanism of Nanocomposite Ceramic in Two-Dimensional Ultrasound Grinding

Surface microstructure of nano-composite ceramics prepared by mixed coherence system and machined by two-dimensional ultrasonic precision grinding was researched using TEM, SEM, XRD detector and other equipments. Structure, formation mechanism and characteristic of metamorphic layer of ground surface of nano-composite ceramics were researched. The experiment shows micro deformation mechanism of ceramic material in two-dimensional ultrasound grinding is twin grain boundary and grain-boundary sliding for Al2O3, and it is crystal dislocation of enhanced phase, matrix grain boundary sliding, coordination deformation of intergranular second phase as well as its deformation mechanism for nano-composite ceramics. The fracture surfaces of nano-composite materials with different microscopic structure were observed using TEM and SEM. Research shows that ZrO2 plays an important influence on the generation and expansion of crack, and enhances the strength of grain boundaries. When grain boundaries is rich in the ZrO2 particles, the crack produced in grinding process will be prevented, and the surface with plastic deformation will be smooth. The results shows nanoparticles dispersed in grain boundary prevents crack propagation and makes materials fracture transgranularly which makes the processed surface fine.

Research on Relationships Between Surface Fracture States and Surface Roughness Dispersion Range in Ultrasonic Grinding ZrO2

On the basis of the relationship between machined surface roughness and cutting parameters of hard-brittle materials, experiments of common and ultrasonic honing ZrO2 engineering ceramics were carried out using coarse diamond grits to discuss the relationship between surface roughness and its dispersion range and surface fracture states. Experimental results show that the machined surface roughness value of hard-brittle materials and the characteristics of its dispersion range can be considered as the criteria of cutting state. Therefore, as the machined surface roughness value and its dispersion range are both rather small, the cutting goes in the ductile cutting state, whilst the machined surface roughness value and its dispersion range are both rather large, the cutting goes in the crack cutting state. When the machined surface roughness value is rather small and its dispersion range is rather large the cutting is in the transition cutting state. Introduction At present with combination to the special machining technology such as ultrasonic, the traditional ultra-precision machining technology for hard-brittle materials has developed a new way to obtain the ductile surface effectively. In 1993, Professor D. Prabhakar put forward a theoretical model of material removal rate for rotating ultrasonic machining engineering ceramics [1] to discuss the theoretical relationship between material removal rate and amplitude, rotating velocity, grit size and machining pressure, and proved that the rotating ultrasonic machining has a relatively lower cutting force and higher material removal rate with the same conditions as common grinding. In 1994, H. Frei and G. Grathwohl studied the microstructure and intensity of advanced ceramics after ultrasonic machining [2], and found out in the process of machining engineering ceramics such as Al2O3, ZrO2 and N4Si3, the material removal process includes both crack and mini-plastic deformation, and the later resulted in higher surface compressive stress and flexural strength. In the same year, Professor X. Ai and D.M. Kim studied the ultrasonic drilling of engineering ceramics [3] and found that ultrasonic machining has smaller cutting force, lower cutting temperature and better surface quality than common way. In 1995, Z.J. Pei investigated the material removal rate of rotating ultrasonic milling MgO and ZrO2 engineering ceramics, and forecasted the relation between removal rate and cutting parameters [4]. A.R Jones worked over the press distributing model of ultrasonic polishing using stamping die [5]. Z.Y. Wang put forward the dynamic model of material removal rate in ultrasonic machining metal accessories [6]. H. Dam studied the productivity, surface quality and dimension tolerance of ultrasonic machining ceramics [7]. In the 48th CIRP annual meeting, B. Varghese and S. Malkin gave a progress report of radial ultrasonic vibration machining, and the results shew contact press, loaded area, working cycle time, ultrasonic vibration and its direction, and slotted wheel have effort on the material removal rate of ZrO2 and Si3N4 [8]. E. Uhlman and G. Spur discussed the surface figuration mechanism of slow-feed grinding advanced ceramics assisted by ultrasonic, reviewed the cut-in mechanism of single grit imposed ultrasonic vibration in the normal direction of workpiece, and forecasted that the axial vibration could get a better machining effect [9]. Obviously these researches focused on the Key Engineering Materials Online: 2004-03-15 ISSN: 1662-9795, Vols. 259-260, pp 239-243 doi:10.4028/www.scientific.net/KEM.259-260.239

Research on the Force Characteristics in Ultrasonic Grinding Nano-Zirconia Ceramics

Nano-ceramics possessed ascendant mechanical property and physical characteristics contrast with traditional engineering ceramics, and its machining with ultrasonic assistance has been considered one of the most efficient methods. In the present paper a novel ultrasonic grinding vibration device has been developed and the theoretical model of grinding force has been created for ultrasonic vibration grinding. The influences of grinding parameters on grinding forces were tested with self-designd acoustic system based on local resonance. According to the test data, the effect of depth of cut and wheel velocity on the grinding force with/without ultrasonic assistance was analyzed. Both in common and ultrasonic grinding the normal grinding force and tangential grinding force descend against the wheel velocity, while ascend along with the depth of cut. In any case the grinding force in ultrasonic grinding was not more that that in common grinding.

Experimental Study on the Dressing Force of Super-Abrasive Grinding Wheel with Elliptic Ultrasonic Vibration

A new dressing device for dense type diamond grinding wheel, whose elliptic vibration was prompted by single longitudinal vibration, was designed using a local resonance method. It was employed to dress the metallic bond super-abrasive grinding wheel and the dressing force characteristics were analyzed. The results indicate that the thrust force decreased to 1/7-1/10 of that of conventional method, and the main cutting force decreased by 70%. Compared to other dressing parameters, the dressing force in elliptic ultrasonic vibration was more sensitive to grinding speed. Thrust force and main cutting force increased rapidly when rotation speed beyond 72rpm. But when the ultrasonic power was higher than 50W, dressing force decreased very slowly. It was observed that the new dressing method is contribute to better surface finish such as more even surface, less crush abrasives, more uniform abrasive abscission and so on than the conventional method.

Experimental Study on the Big Nano-Ceramic Plates under Two-Dimensional Ultrasonic Polishing

The two-dimensional ultrasonic polishing device of big nano-ceramic plate was designed and its maximum value of vibration amplitude reached 18.34um.Using it to polish the nano-zirconia toughened alumina ceramic(ZTA) plates 500mm×400mm×16mm, the polishing efficiency improves and the polishing surface roughness achieves below 0.07um, flatness below 10um.

Study on Cutting Force and Tool Wear of High Volume SiC/Al MMCs with Ultrasonic Vibration High Speed Milling

Particle-reinforcement aluminum-based metal matrix composites (MMCs) are widely applied in the aviation, aerospace and military fields due to their excellent physical and mechanical properties. But the further application of the materials is hampered owing to its difficultly machining characteristics. There are unique advantages while cutting hard and brittle materials with ultrasonic vibration. The ultrasonic vibration high-speed milling (ultrasonic milling) is a reasonable cutting method in which combined the advantages of high-speed milling (conventional milling) and ultrasonic milling. The machining performances of high volume SiCp/Al MMCs were studied by conventional milling and ultrasonic milling in this paper. The influences of the milling parameters on the milling force were investigated in the experiment. In addition, the wear and mechanism of tool were analyzed in ultrasonic milling. The results show that the cutting force, abrasive wear were reduced, and tool lives were increased effectively during ultrasonic milling of SiCp/Al MMCs.