Papers by Author: Chang Yi Liu

Abstract: Drilling experiments of titanium alloy Ti6Al4V were conducted. Taking the speed and feed as the process variables, a set of experimental cutting forces are obtained and compared. From the experimental results it is concluded that within the experimental extent the thrust force and torque of drilling process rises with the feed rate. The lower spindle speed resulted in the greater amount of thrust. Feed rates have greater influence on the thrust force than the spindle speed. The combination of greater feed rate and lower spindle speed results in the maximum amount of thrust. However, combination of greater feed rate and spindle speed resulted in maximum amount of torque.

Abstract: In this paper Finite element methods (FEM) and cutting experiment were used to investigate the machinability of titanium alloy ZTC4 (cast Ti6Al4V). Machinability was evaluated as cutting force, temperature, and surface roughness. Two-dimension (2D) and three-dimension (3D) machining process FEM models were established. Material constitutive applied Johnson-Cook model synthesizing elastic and plastic deformation. Chip separated criteria adopted arbitrary Lagrangian Euler (ALE) algorithm. Heat generation source included the rake face chip flow under conditions of seizure and chip/tool friction, clearance face tool/workpiece friction. 3D discrete milling tool was modeled and the milling process was simulated. The ZTC4 milling experiments were designed and carried out with same cutting conditions of the 3D FEM simulation. The results of FEM simulation and the experiment were compared and analysed. The influences of the machining variables to the machinability of ZTC4 were discussed.

Abstract: In this paper Finite Element Methods (FEM) were used to simulate the ultrasonic vibration Orthogonal cutting of titanium alloy Ti6Al4V. Machining conditions were similar to those used for manufacture. Material constitutive applied Johnson-Cook model combining elastic and plastic deformation, the material hardening for extreme shear strain and strain rate, material softening for adiabatic shear of chip flow-zone. Chip separated criteria adopted arbitrary Lagrangian Euler algorithm (ALE). Heat sources included the rake face chip flow under conditions of seizure and chip/tool friction, clearance face tool/workpiece friction. Thus, the orthogonal ultrasonic vibration machining of Ti6Al4V FEM models were established. The simulation results included the chip formation, the cutting force/stress and temperature distributions through the primary shear zone and the chip/tool contact region. The cutting force, cutting temperature of the ultrasonically and conventionally machining were compared. The reasons of the decrease of chip deformation coefficients, cutting force and temperature and the increase of shear angle in ultrasonic machining were discussed.

Abstract: This paper presents a study of the Taguchi design methodology, which is applied to optimize flank milling operation parameters when machining titanium alloy Ti-6Al-4V in conventional and high speed regimes. This study includes cutting speed, feed rate and depth of cut. Experimental runs are conducted using an orthogonal array of L9(33), with measurement of surface roughness. ANOVA analyses are carried out to analyze the effect of these operation parameters, and the optimal parameters combination is determined by seeking the best surface roughness. The analysis of result shows that the optimal combination for good surface roughness is high cutting speed, low feed rate. Finally, confirmation run verifies the results, which indicated that Taguchi method is both efficient and effective in determining the Ti-6Al-4V flank milling parameters for the optimization with minimum number of trials.

Abstract: Taguchi design methodology is applied to experiments of flank mill machining parameters of titanium alloy TC11 (Ti6.5A13.5Mo2Zr0.35Si) in conventional and high speed regimes. This study includes three factors, cutting speed, feed rate and depth of cut, about two types of tools. Experimental runs are conducted using an orthogonal array of L9(33), with measurement of cutting force, cutting temperature and surface roughness. The analysis of result shows that the factors combination for good surface roughness, low cutting temperature and low resultant cutting force are high cutting speed, low feed rate and low depth of cut.