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Rendi Kurniawan,고태조 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1
We herein propose a cutting force model in a micro-dimple pattern process using the two-frequency elliptical vibration texturing (TFEVT) method. The TFEVT method decreases the cutting force compared to the conventional texturing (CT) method owing to the intermittent cutting behavior. The cutting force model in the TFEVT method is formulated, in which the shear angle is assumed as a transient and the transient area of cut of the micro-dimple is determined. The transient area of cut of the micro-dimple can be determined by obtaining the starting and ending time of cutting, while the shear angle can be determined by Cerniway’s hypothesis. Finally, the cutting force model was compared with the experimental cutting force value. The comparison results show that the cutting force simulation is in agreement with the experimental cutting force value. The experimental results also show that the cutting force in the TFEVT method is lower than that in the CT method.
Rendi Kurniawan,Saood Ali,박기문,Chang Ping Li,고태조 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.7
A three-dimensional ultrasonic elliptical vibration transducer (3D-UEVT) based on a sandwiched piezoelectric actuator for micro-grooving was manufactured and assessed in this study. The 3D-UEVT generates an elliptical locus of a tool tip in three-dimensional space. The 3D-UEVT operates in resonance mode by coupling the first longitudinal-vibration mode and the two directions of the third bending-vibration mode. Modal simulation analysis was performed to determine the proper dimensions to ensure that the resonance frequencies between the longitudinal and two of the bending-vibration modes were similar. The swept-sine assessment indicated that the 3D-UEVT working resonance frequency was approximately 20.4 kHz. The 3D-UEVT generated an amplitude peak-to-peak of approximately 0.8 µm in two-bending directions and 0.3 to 0.5 µm in the longitudinal direction when the piezoelectric sandwiched actuator was driven at a peak-to-peak voltage of 150 V. The output amplitude of the 3D-UEVT increased as the driven input voltage increased. The performance of the proposed 3D-UEVT was assessed by a micro-grooving test. An adequate micro-grooving result confirmed that the proposed 3D-UEVT produced an acceptable micro-groove pattern.
A Study of Surface Texturing Using Piezoelectric Tool Holder Actuator on Conventional CNC Turning
Rendi Kurniawan,고태조 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.2
Tribology studies have recently shown the beneficial reduction in the friction coefficient of various mechanical components by application of surface texturing. This study presents a study of surface texturing using a piezoelectric tool holder actuator whereby the tool holder installed on a conventional computerized numerical controlled (CNC) machine lathe. The tool holder used in surface texturing a workpiece surface, yields average strokes up to 26 μm and has a natural frequency of approximately 480 Hz. A piezo actuator of 15 μm maximum displacement was utilized, and a single parallel four-bar flexure hinge mechanism magnified the input displacement from the piezo actuator by an amplification ratio of 3:1. In this study, a piezo actuator that operated under the open-loop condition, in modulation frequency range from 100 Hz to 135 Hz, was imposed to cut into the workpiece surface to build a pattern of dimples. Moreover, the characteristics of the dimple-pattern topography were investigated by varying the spindle rotation rate between 30 rpm and 100 rpm at constant modulation frequency of 120 Hz. According to the experimental results, Al 6061-T6 and AISI 1045 were successfully textured by using the piezoelectric tool holder actuator. The results showed that the maximum errors of the dimple feature on Al 6061-T6 and AISI 1045 were approximately 10.14% and 47.97%, respectively, between the analysis and experimental results.