Papers by Keyword: Elliptical Vibration Cutting

Abstract: In ultrasonic vibration the cutting edge of a tool is vibrated in the principal or cutting direction, generally at a constant ultrasonic frequency. The main characteristic of this cutting method is its intermittent nature involving repeated cutting and pausing. In this paper, ultrasonic elliptical vibration cutting is used to assist micro-groove turning of cylindrical surfaces. The elliptical locus during the cutting process is generated by a newly designed 2D resonant ultrasonic vibrator. A series of experiments were performed to verify the effects of the ultrasonic elliptical vibrations. The generated cutting forces and burr formation were compared for the ordinary and the elliptical vibration-assisted cases. Comparison results show the effectiveness of the elliptical vibration cutting method in reducing cutting forces and alleviating burr formation.

Abstract: Elliptical vibration cutting (EVC) process and three dimensional cutting surfaces are analyzed in this paper to understand the formation of surface topography. The model of EVC surface topography is established based on curved surface remove function under the assumption that the tool edge is sharp enough. And simulation analysis of surface topography is conducted with different feed offset ratios. Results indicate that RMS change with feed offset ratios λ. The range of RMS is larger when feed offset ratio ranges from both 0 to 0.4 and 0.6 to 1, while the range is smaller when feed offset ratio changes from 0.4 to 0.6. Whats more, RMS reaches the minimum when feed offset ratio is 0.5. The present research provides some references for reducing the height of vibration ripples and improving EVC surface quality.

Abstract: According to the surface formation mechanism of elliptical vibration cutting (EVC), EVC process and three dimensional cutting surfaces are analyzed in this paper. The model of EVC surface topography is established based on curved surface remove function under the assumption that the tool edge is sharp enough. Simulation analysis of surface topography is conducted to verify the established model. The present research clarifies the law that cutting parameters influent on EVC surface topography. Whats more, it provides some references for optimizing the selection of EVC cutting parameters and further improving EVC surface quality.

Abstract: Elliptical vibration cutting (EVC) is one of the main methods to use diamond tool machining of hard to cutmaterial. Accurate prediction of cutting force in elliptical vibration cutting process is not only an important basis to properly choose of cutting parameters and optimal tool geometry parameters, but also a key factor to improve the processing property of cutting. A method to build cutting force theory model in EVC is presented in this paper. Eigen decomposition of the elliptic motion locus first ,then getting the piecewise function of the cutting force model. Based on simulation analysis of the cutting force model, this paper predict the rules that vibration amplitude and angle of tool geometry affect on cutting force, which provide theory basis for choose cutting parameters and cutting tool parameter in EVC.

Abstract: Tungsten carbide is a crucial material for glass molding in optical industry. The present study investigated a feasibility of ductile machining of sintered tungsten carbide for glass molding by applying ultrasonic elliptical vibration cutting technology with single crystal diamond tool. Grain size and binder material of sintered tungsten carbide have an influence on hardness and/or toughness of the material. Binder material also has a chemical affinity to diamond. In order to examine the influence of material composition on ductile machining of tungsten carbide, a series of grooving and planing experiments were conducted to several different tungsten carbide workpieces with the different binder phase and the different grain size. The experimental results indicated that micro grooving in a ductile mode can be attained successfully by applying ultrasonic elliptical vibration cutting, while finished surface deteriorates with brittle fractures in ordinary cutting. It was also clarified that grain size and binder material have significant influence on the deteriorations in the surface quality, the tool shape and the cutting forces.

Abstract: To maximize cutting performance of elliptical vibration cutting (EVC) (also known as two-dimensional vibration assisted cutting), the elliptical trajectory of a cutting tool needs to be corrected. In this study, the effect of the shape of the elliptical trajectory on the machining characteristics of EVC is investigated. Various elliptical trajectories were created by modulating the relative phase and magnitude of the sinusoidal input voltages to the piezoelectric actuators and the effect of tilt angle of the elliptical trajectory on the machining quality such as the cutting resistance and machining quality is experimentally observed in successive micro-V grooving as the tilt angle is changed between 0^o, 30^o, -30^o, and 90^o. It is found that the tilt angle significantly affects both the cutting resistance and machining quality.

Abstract: The elliptical vibration cutting (EVC) technique has been found to be a promising technique for ultraprecision machining of various materials. Researchers have proved that the EVC technique prevails over both conventional cutting and 1D vibration cutting techniques in most aspects in terms of cutting performances. However, during the EVC process, vibration marks or cusps are generated by the elliptical vibration locus and can result in an increase in the overall roughness of machined surface, which is undesirable for achieving high-quality mirror surface. Although researchers have developed a calculation method for the height of the cusps, only the effects of vibration frequency on surface generation were studied, and the effects of the other vibration and machining parameters have not been investigated in detail by previous researchers. Hence, in the present study, in order to deeply understand surface generation process along nominal cutting direction under the EVC technique, which is critical for its performance improvement and application, an experimental study comprising a series of grooving tests was carried out. The effects of nominal cutting speed on the surface generation at two different thrust-directional vibration amplitudes are investigated. Analysis is given for the comparison between the theoretical and experimental roughness values, showing that there exists a critical nominal cutting speed, below which the measured roughness value is quite small and the vibration marks are almost undetectable.

Abstract: In order to reveal the mechanistic characteristics during the elliptical vibration cutting (EVC), A simplified 2-D finite element model is developed. The characteristics of the cutting forces during the EVC process are investigated by comparison with the conventional cutting. The results indicate that the lower averaging values of cutting forces can be obtained and an obvious inverse phenomenon of the thrust force is also observed during the EVC process, which may be beneficial to the chip formation. A detailed analysis of the equivalent stress distribution during the EVC process is carried out. A transient stress distribution is observed during the EVC process, the highly localized Von Mises stress in the tool-chip contact region throughout one EVC cycle may help to form a more continuous chip and lead to the ductile regime removal of brittle materials.

Abstract: Based on ultrasonic elliptical vibration cutting (UEVC) model, kinematical formulas of elliptical vibration cutting(EVC) is established, the paper presented relationship of vibration parameters effecting on surface roughness, machining accuracy and machining efficiency, revealed UEVC characteristics of high frequency and small amplitude are more conducive to improve surface roughness, advance EVC machining efficiency. Experiences of cutting the weak rigidity workpiece by the designed adjusting frequency elliptical transducer is proved that compared conventional turning, increasing vibration frequency and decreasing amplitude are result in improve surface roughness, and compared low frequency EVC, decrease amplitude are result in reduce the height of vibration ripples in cutting direction, and advance machining efficiency. So high frequency and small amplitude EVC is more conducive to precision machining and ultra-precision machining.

Abstract: Based on analysis of the micro-surface and kinematical formulas of elliptical vibration cutting(EVC), the paper presents that frequency and amplitude of vibration parameter affect surface roughness, forming accuracy and machining efficiency of weak rigidity workpiece: increase vibration frequency are result in lower vibration cutting duty cycle , lower cutting force, advancer critical speed, so advance forming accuracy and machining efficiency; decrease amplitude are result in reduce the height of vibration ripples in cutting direction , so improve surface roughness. Experiences of cutting the weak rigidity workpiece by the designed double bending hybrid vibration high transducer, verified that the high frequency elliptical vibration cutting are proved more conducive to machining weak rigidity workpiece.