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Development of a two-frequency, elliptical-vibration texturing device for surface texturing
쿠르니아완렌디,고태조,Li Chang Ping,띠뚜말라이쿠마란,Gandjar Kiswanto,Ping Guo,Kornel F. Ehmann 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
This study presents the design of a Two-frequency, elliptical-vibration texturing (TFEVT) device. The device was designed to be used in a surface texturing process, and its functionality is based on a combination of ultrasonic (> 20 kHz) and low vibration frequencies (< 100 Hz). The device consists of two parts: The Ultrasonic elliptical motion transducer (UEMT) and the Low frequency displacement amplifier (LFDA). A modal analysis simulation and dynamic experiments were conducted to investigate the dynamic characteristics of the device. The modal simulation was carried out using finite element analysis and the dynamic experiment was evaluated using Frequency response function (FRF) analysis. The working principle of the UEMT is based on a resonance transducer, and the angle between the two Langevin transducers was set as 90 o . The UEMT has two vibration modes, symmetric and asymmetric, and according to experimental data, its working frequency is 24 kHz at the 6 th resonance vibration mode when a Polycrystalline diamond (PCD) tool is attached. The UEMT is able to generate an elliptical locus that has a vertical amplitude of 1.4 µm and a horizontal amplitude of 0.6 µm, under a phase-shift of 90 o . The design of the LFDA is based on a double parallel four-bar flexure hinge, and the displacement output ratio is set to 5. The working principle of the LFDA is based on a non-resonance transducer. The working frequency of the LFDA is below its first of natural frequencies (≈1060 Hz), and it is able to generate sinusoidal motion with a maximum peak-to-peak amplitude of 9 µm. Finally, to investigate the feasibility of the TFEVT device for use in a surface texturing process, several micro-groove cutting tests were performed on an AISI 1045 alloy steel.
띠뚜말라이쿠마란,고태조,쿠르니아완렌디,Changping Li,M. Uthayakumar 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
This study discusses the development of an Adaptive neuro–fuzzy inference system (ANFIS) model for determining the surface roughness (Ra) during machining of multidirectional woven fabric Carbon fiber reinforced plastics (CFRP) using Abrasive waterjet machining (AWM). Three variable input parameters—Jet pressure (JP), Traverse speed (TS), and Standoff distance (SOD)—were selected to assess the roughness of the CFRP along the traverse direction of the cut surface. The experimental results show that a lower JP deteriorated the finish by creating surface rupture. On the other hand, a poor surface finish was observed in the case of machining at higher TS and SOD. Further, the developed ANFIS model was used to validate the results and it was found that the predicted values were in good agreement with a 95 % confidence level. It was also evident that the ANFIS technique is helpful for better prediction of the experimental data with minimum error. Finally, the cut surface morphology was analyzed using a 3D non-contact surface profilometer and the results are discussed.
Experimental investigation of burr reduction during EDM end-milling hybrid process
김민엽,Chang Ping Li,쿠르니아완렌디,정상태,고태조 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6
Burrs are always generated during the end-milling process of ductile materials and have become a common challenge because a large plastic flow of the material is generated during cutting. In this research, a combination method of the end-milling and electrical discharged machining (EDM) process is proposed to suppress the generated burrs during machining; this process is called the EDM endmilling process. EDM end-milling was performed for side milling of AISI 1045 alloy steel (HRC = 28). The height of the generated burrs was measured and compared between ordinary end milling and EDM end-milling, and the experimental results indicate that the generated burrs are suppressed effectively by EDM end-milling owing to the effect of reduced plastic flow. The experimental results also indicate that the height of the generated burrs decreases when the capacitance values are increased during EDM end-milling. Furthermore, the results show that the height of the generated burrs remains unchanged by EDM end-milling when the axial depth of cut is increased.
정상태,S. Thirumalai Kumaran,Changping Li,쿠르니아완렌디,고태조 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9
Micro-dimple formation improves the tribological behavior of a material. This study investigates dimple formation on a titanium (Ti-6Al-4V) alloy by using electrical discharge drilling. Input parameters, namely capacitance (C), pulse-on-time (Ton), and voltage (V), were varied to measure the output quality responses including dimple depth, burr height, and burr width. The experimental results indicated that the quality of the dimple is determined based on the spark energy and rate of material removal. A regression analysis was performed for each output response. The developed model confirmed the fitness at a 95 % confidence interval. The contribution of each factor and its significance was determined by using analysis of variance (ANOVA). Further, the optimum drilling condition was predicted by using desirability analysis (C = 10000 pF, Ton = 100 µs, and V = 180 V). The microscopic view of the dimple array and the micro-dimple geometry were analyzed by using scanning electron microscopy images.