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- 저자 : Yukui (검색결과 8 건)
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Residual Surface Topology Modeling and Simulation Analysis for Micro-Machined Nozzle
Yukui Cai,Zhan-qiang Liu,Zhen-yu Shi,Qinghua Song,Yi Wang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
The performance of the micro nozzle is determined primarily by its machined surface topology. A circular cross-section micro-Lavalnozzle is modeled and studied by using numerical simulation in this paper. The geometry of residual height and residual area ofmachined nozzle surface with flat-end milling cutter and ball-end milling cutter are created. It is found that the ball end milling cutterwith large diameter is better than the flat one for nozzle finishing operations. The nozzle velocity performance is also revealed in thisresearch. When residual height increased from 0.6 μm to 9.6 μm for nozzle with throat diameter less than 2 mm, the maximum outletvelocity of nozzle reduced gradually. The maximum outlet velocity of nozzle remains stable for the nozzle with throat diameter greaterthan 2 mm. The results show that the maximum outlet velocity of nozzle significantly reduces with throat diameter decreasing underconstant residual height. Based on the analysis about velocity boundary layer, when residual height changing from 0.6 μm to 9.6 μm,the nozzle with throat diameter is 1 mm, has the boundary layer thickness ranging from 5% to 14% of outlet radius.
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Zhaoxi Zhao,Yukui Wang,Zhen-long Wang,Jianyong Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2
Thermal error is a major factor influencing the accuracy of large precision electrical discharge machining (EDM) machine tools, especially when processing continuously for a long time. In this paper, a novel thermal analysis model was set up to identify the static and dynamic thermal behaviour of the large EDM machine tool. The thermal effect of multiple spark discharges is considered. An equivalent heat flux method was proposed to model the intermittent heat flux for the first time. Both the steady and transient analyses were applied to investigate the thermal equilibrium time of critical points. It is found that when the study point is far away from the heat source, the longer thermal equilibrium time is needed. And the thermal equilibrium time of the machine tool was also estimated. Verification experiment has been performed, indicating the simulation accuracy of 87 % on the temperature rise of the electrode. Moreover, on the displacement of the spindle, the simulated result matched with the experimental result in Z direction error of 7 %. Finally, suggestions for reducing the thermal deformation were proposed to further improve the machining accuracy of large EDM machine tools.
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Zhaoxi Zhao,Jia Zhang,Yukui Wang,Zhen-long Wang,Jianyong Liu,Chenghao Quan 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
Thermal error which has been widely studied in cutting machine tools, was ignored in the EDM machines in most cases, since there is usually no high-speed rotation for spindles. However, for large die-sinking EDM machines, due to heavy load of drive system and long processing cycle of large aeronautical parts, thermal error induced by jump motion has seriously impaired the machining accuracy and gradually been recognized. In this paper, the dynamic thermal behavior of spindle induced by periodic jump motions in large precision die-sinking EDM machine was studied for the first time. Noted that the Z-axis base and column show obvious temperature rise and the thermal error in Y direction is the largest, which is about 6.5 and 5 times compared with that in X and Z directions. Based on this, an efficient thermal error prediction model was presented. Thermal sensitive points were picked out through fuzzy clustering and correlation theory, taken as inputs of radial basis function (RBF) neural network to guarantee the accuracy. As a result, the prediction accuracy in X, Y and Z directions are 95.2 %, 92.5 % and 94.4 %, respectively. Finally, the effect of jump period on spindle thermal behavior was investigated, and suggestions for optimizing jump motion parameters were proposed to further improve the machining accuracy of large EDM machines.
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Investigation on MRR and Machining Gap of Micro Reciprocated Wire-EDM for SKD11
Xiang Chen,Zhen-long Wang,Yukui Wang,Guanxin Chi 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.1
In this paper, the investigational work is carried out on the micro reciprocated wire electrical discharge machining (wire-EDM) of SKD11 using circularly travelled wire with Φ30 μm as tool electrode, aiming to achieve the fabrication of micro parts with high cost-effect, efficiency and precision. The experiments are systematically performed using central composite design approach of response surface methodology to study the effect of open voltage, discharge capacitance, pulse duration and feed rate on material removal rate (MRR) and machining gap. The mathematical models of MRR and machining gap are developed by analysis of variance, and whilst verified by confirmation experiments with ≤ 8.38% and 6.70% prediction errors for MRR and machining gap, respectively. Besides, multi-objective optimization of parameter combinations is attempted by non-dominated sorting genetic algorithm-II. Finally, a typical experimental sample, micro gear is successfully machined with 1194.38 μm tip diameter under the condition of No. 14 optimal solution.
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Sirui Gong,Han Wang,Xiaolong He,Zhenlong Wang,Yukui Wang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4
SiCp/Al, as a new material, is widely used for its excellent wear resistance, corrosion resistance and other properties. Micro-holes are important but difficult to obtain on this ceramic material especially in curved surface. In this paper, taking micro bearing bush as an example, a micro-EDM and in-situ micro-reaming method is put forward for preparing micro through holes and micro eccentric holes on SiCp/Al cambered surface, without secondary clamping or tool change. High machining efficiency, low wear and no recasting layer can be achieved by this method. Here, machining characteristics is studied in hole micro-EDM on SiCp/Al, small taper and high efficiency machining is realized by comparing four electrical discharge drilling technique. Carbon deposition and tool wear are related to electrical parameters according to experimental exploration. After determining the discharge gap, taper and recast layer thickness, a segmented tool is designed, which can use the lower part to perform micro-EDM with the taper of 1.04°, MRR is 0.069 mm3/min, and the TWR is 3.22%. Then only needs to continue feeding the tool, the upper part of the tool can be used to achieve reaming, which can fully remove the recast layer, and decreases the roughness of hole wall from Ra 1.452 μm to Ra 0.803 μm.
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Comparison of volatile components in fresh and dried Zanthoxylum bungeanum Maxim
Wenlin Zhang,Si Tan,Wanpeng Xi,Jianlei Yang,Qinhong Liao,Jianbin Lan,Yukui Lv,Jianmin Tang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.4
Fresh and dried Zanthoxylum bungeanumMaxim volatiles of two main cultivars including Dahongpaoand Meihuajiao, were determined through GC–MS andcompared. In all the tested samples, linalool, D-limonene,eucalyptol, 3-nonanone, and b-myrcene were identified asthe five predominant components. The percentages of thesecomponents in fresh Dahongpao were 23.89%, 21.04%,7.46%, 5.63% and 5.87%, respectively. Similar percentages,27.28%, 17.62%, 6.39%, 1.66% and 7.8%, werefound in dried Dahongpao. In general, the contents oflinalool and b-myrcene in dried Dahongpao and Meihuajiaowere slightly higher than those in fresh samples,whereas the contents of D-limonene, eucalyptol, and3-nonanone were lower. Partial least squares discriminantanalysis results showed that the two cultivars could beclearly differentiated based on volatiles, whereas, the freshand dried Zanthoxylum bungeanum Maxim samples couldnot. This demonstrated that the drying process had nosignificant effect on the volatiles.
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