A novel three-dimensional elliptical vibration cutting device based on the freedom and constraint topologies theory

Author(s):  
Sheng Lin ◽  
Xi Kong ◽  
Chun Wang ◽  
Yun Zhai ◽  
Liang Yang

Aiming at the issue of the lack of the design theory for the three-dimensional elliptical vibration cutting device, a compliant mechanism with two rotations and one translation is synthesized based on the theory of freedom and constraint topologies. And a three-dimensional elliptical vibration cutting device is proposed on the basis of the compliant mechanism. The relationship between the critical speed and the length of the tool bar is analyzed. Simulation is conducted to analyze the influence of parameters on the output ellipse. Experiments are conducted to verify the validity of the elliptical vibration cutting device. The relationship between the roughness and the cutting speed is obtained. Experiments with different driving frequencies are conducted without the change of other parameters. Results show that the proposed compliant mechanism is feasible for the elliptical vibration cutting device. Compared with the common cutting, the new elliptical vibration cutting device has a better performance in the processing effect. This provides an important reference for design of the elliptical vibration cutting device.

2014 ◽  
Vol 490-491 ◽  
pp. 600-606
Author(s):  
Jie Qiong Lin ◽  
Jin Guo Han ◽  
Dan Jing ◽  
Xian Jing

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.


Author(s):  
Sen Yin ◽  
Zhigang Dong ◽  
Yan Bao ◽  
Renke Kang ◽  
Wenhao Du ◽  
...  

Abstract Ultrasonic elliptical vibration cutting (UEVC) technique, as an advanced cutting method, has been successfully applied to machine difficult-to-cut materials for the last decade. In this study, the mechanism of the elliptical vibration locus caused by the “asymmetric structure” of the horn was analyzed theoretically firstly, and the corresponding relationship between the degree of asymmetry and the elliptical vibration locus was determined based on finite element method (FEM). Then an efficient single-excitation UEVC device with “asymmetric structure” was developed and optimized. The resonant frequency of the device was 40.8 kHz, and the amplitude reached 12.4 µm, which effectively broke the limitation of cutting speed in UEVC. Finally, the UEVC device's performance was tested, and the advantages in improving the tungsten alloy surface quality and reducing diamond cutting tool wear validated the technical capability and principle of the proposed device.


2013 ◽  
Vol 331 ◽  
pp. 254-259
Author(s):  
Jie Qiong Lin ◽  
Jin Yue ◽  
Xiao Ping Gao ◽  
Tong Han Ran

The three-dimensional elliptical vibration cutting can realize high efficient and low cost of method of optical free surface cutting, whose effective drive form is the stack of piezoelectric ceramics to achieve the vibration in three directions . but the crosstalk phenomenon generated in the process of the piezoelectric movement make the tool deviate the ideal trajectory so that seriously affect the quality of the workpiece surface, damage the tool. Thus a method of removing the crosstalk generated in the three-dimensional elliptical vibration cutting device and its control system is proposed in the paper. The control system model of a three-dimensional elliptical vibration cutting is established, then, the crosstalk data is assumed, using the least squares method to fit the date, crosstalk compensation algorithm is obtained so that the crosstalk removal module can be designed to remove the crosstalk generated the piezoelectric movement ,the final section is the simulation-based analysis, the simulation results show that the method can meet the control requirements of the three-dimensional elliptical vibration, the crosstalk of piezoelectric movement can be removed effectively.


Author(s):  
Chandra Nath ◽  
Mustafizur Rahman ◽  
Ken Soon Neo

In recent years, the ultrasonic elliptical vibration cutting (UEVC) technique has been found to be an efficient method for the ultraprecision machining of hard and brittle materials. During the machining at a given nominal depth of cut (DOC), the UEVC technique, because of its inherent mechanism, effectively reduces the thickness of cut (TOC) of the workpiece material through overlapping vibration cycles. For the ductile machining of hard and brittle materials, this TOC plays a critical role. However, the relationships between the nominal DOC, the TOC, and the relevant machining parameters have not yet been studied. In this study, the role playing machining parameters for the TOC are firstly investigated and then theoretical relations are developed for predicting the maximum TOC (TOCm) with respect to the relevant machining parameters. It is found that four machining parameters, namely, workpiece cutting speed, tool vibration frequency, and tangential and thrust directional vibration amplitudes, influence the TOCm. If the speed ratio (ratio of the workpiece cutting speed to the maximum tool vibration speed in the tangential direction) is within a critical value 0.12837, then a reduced TOCm can be obtained. It is also realized that if the TOCm can be kept lower than the critical DOC (DOCcr), then ductile finishing of brittle materials can be achieved. The above phenomenon has been substantiated by experimental findings while machining a hard and brittle material, sintered tungsten carbide. The findings suggest that the same concept can be applied for the ductile cutting of other hard and brittle materials.


2011 ◽  
Vol 314-316 ◽  
pp. 1851-1856 ◽  
Author(s):  
Xin Quan Zhang ◽  
A. Senthil Kumar ◽  
Mustafizur Rahman

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.


2014 ◽  
Vol 487 ◽  
pp. 479-483
Author(s):  
Jie Qiong Lin ◽  
Xian Jing ◽  
Tao Xu ◽  
Ming Ming Lu ◽  
Dan Jing

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.


Micromachines ◽  
2017 ◽  
Vol 8 (10) ◽  
pp. 306 ◽  
Author(s):  
Mingming Lu ◽  
Jiakang Zhou ◽  
Jieqiong Lin ◽  
Yan Gu ◽  
Jinguo Han ◽  
...  

2018 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Mingming Lu ◽  
Bin Chen ◽  
Dongpo Zhao ◽  
Jiakang Zhou ◽  
Jieqiong Lin ◽  
...  

Three-dimensional elliptical vibration cutting (3D-EVC) is one of the machining methods with the most potential in ultra-precision machining; its unique characteristics of intermittent cutting, friction reversal, and ease of chip removal can improve the machinability of materials in the cutting processes. However, there is still not much research about the chattering phenomenon in the 3D-EVC process. Therefore, based on the empirical mode decomposition (EMD) technique and feature extraction, a chatter identification method for 3D-EVC is proposed. In 3D-EVC operations, the vibration signal is collected by the displacement sensors and converted to frequency domain signal by fast Fourier transform (FFT). To identify tool cutting state using the vibration frequency signal, the vibration signals are decomposed using empirical mode decomposition (EMD), a series of intrinsic mode functions (IMFs), so the instantaneous frequency can be reflected by the vibration signals at any point. Then, selecting the primary IMFs which contain rich chatter information as the object in feature extraction identification, and two identification indexes, that is, the mean square frequency and self-correlation coefficient, are calculated for the primary IMFs by MATLAB software, to judge the chatter phenomenon. The experimental results showed that the mean square frequency and self-correlation coefficient of the three cutting states increase with the increase in the instability of the cutting state. The effectiveness of the improved chatter recognition method in 3D-EVC machining is verified.


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