Papers by Author: Wu Yi Chen

Abstract: A multidimensional loading material testing machine (MLMTM) based on Stewart Platform is proposed in this paper. The kinematic and dynamic characteristics of MLMTM are analyzed, including the influence of universal joint in each limb on dynamic modeling. The dynamic model is established via Kane method, and the control system is founded based on classic PID strategy. Four experiments are performed to examine the validity of proposed dynamic model and control system of the MLMTM, including two uniaxial experiments and two biaxial experiments. Results of these experiments are summarized as well as the capacity of force tracking and load errors are analyzed. The experimental results demonstrate the validity of dynamic model via Kane method and illustrate that the proposed MLMTM is capable of performing multidimensional loading tests.

Abstract: In order to reduce manufacturing cost, a methodology of accuracy synthesis for machine tool was recommended by combining both machining cost and Least Square method. Weighted coefficients representing the machining difficulty of manufacturing processes were introduced. 3PRS/UPS redundant parallel kinematic mechanism (3PRS/UPS PKM) was taken as an example, and its component tolerances were derived by the proposed method. Comparing with conventional method, the component tolerances were allocated reasonably. A further tolerance allocation for spherical and rotational joints was studied in detail. And hence, the producibility of component was improved and the manufacturing cost was reduced. The results showed that the proposed method was capable of producing tolerance allocations economically and accurately.

Abstract: In this paper, tool life, tool wear criteria, initial wear and cutting length at initial wear are picked out from 295 milling tool wear curves to calculate initial wear rate K0, final wear rate K1 and the ratio K between the two. By statistic analysis of K0, K1 and K, a statistical regularity between K0 and K1 is found, which indicates that the faster the initial wear, the shorter the tool life would be. Based on the statistical regularity, a milling tool rapid selection method is proposed, and an experiment on selecting the best tools for machining TC4 is carried out to verify the method. The results show that the method can reduce the consumption of material and time significantly, which confirm the efficiency of the method.

Abstract: A methodology to determine the flow stress of material was presented and Johnson–Cook (JC) constitutive model of titanium alloy Ti6Al4V was obtained based on cutting experiment and optimization. This JC model was verified by comparison between simulations with different JC models respectively and experiment. It showed that the accuracy of simulation of cutting force has an increase and the new model is more suitable for cutting simulations. This simple method could improve the accuracy and reliability of the cutting simulation, and could be used to establish the constitutive model of workpiece with more accuracy.

Abstract: The machining of titanium alloys classified as difficult machining materials. It is a major problem how to improve the machining efficiency of titanium alloys. The TC4 and YS8 natural thermocouple pair was calibrated and the variation of electromotive force with change of temperature was obtained. The calibrated results were used to measure the cutting temperature while machining TC4 and the variation regulation of cutting temperature with cutting speed was obtained.