http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Research on Fixture Hole Drilling Quality of Printed Circuit Board
Xiaohu Zheng,Dapeng Dong,Lixin Huang,Qinglong An,Xibin Wang,Ming Chen 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Printed circuit board (PCB) fixture hole is used for installing PCB board or fixing PCB board during drilling process. The drilling quality parameters involve burr size, hole wall roughness et al. In order to improve drilling quality, proper drilling parameters and tool geometries are important especially the tool geometries. In this study, the drilling machinability of PCB fixture hole is studied,effects of drilling parameters on thrust force, drilling temperature and quality are discussed. The experimental results show that resin will be melted during the drilling process. The increase in spindle speed will lead to drilling temperature rise. The fuzzing and spalling of glass fibers result in the generation of hole wall roughness. The exit burrs and enter burrs are generated from drilling copper foils which located in the upper and lower surfaces. The heights of exit burrs are increased with the elevated feed. Drilling experiments are carried out with 9 drill bits which have different point angles, helix angles and length of chisel edges. Analysis of variance (ANOVA) is carried out for hole quality parameters. Desirability function method is used in multiple response optimization to obtain the optimal tool geometry parameters.
Hole Diameter Deviation Control Method for Robotic Hole-Making System Based on Presser Foot Action
Xiaohu Zheng,Guanyao Zhang,Chao Zhou,Guoqiang Guo 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.2
Robotic hole-making systems are widely used in aerospace, automotive and other fields, mainly for diverse and structurally complex parts processing tasks. However, the industrial robot automatic hole-making system is an open-chain multi-bar tandem mechanism, which is prone to quality problems such as unstable cutting process, large hole diameter deviation and hole wall surface defects when performing tasks such as hole-making. This article constructs a stiffness enhancement model for the axial and horizontal directions of the robot presser foot based on the robot end stiffness enhancement method and analyzes the impact of pressure changes on hole-making quality under the action of the presser foot. Through experimental data analysis, the aperture deviation decreased by 32.91% compared to before the pressure foot and the average height of outlet burrs decreased by 85.3%, verifying the feasibility of the method.
Xiaohu Wu,Jun Xu,Xingang Liu,Feng Shou Dong,Yanbing Wu,Ying Zhang,Yongquan Zheng 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
A simple, quick and reliable analytical method for the confirmation and quantification of propisochlor was developed. The propisochlor was extracted from water, soil and rice (stalks, rice and hull) matrices using acetonitrile, and cleaned up with primary secondary amine and determined by UPLC-MS/MS. The LODs of propisochlor ranged from 0.03 μg/kg to 0.12 μg/kg, while the LOQs ranged from 0.1 μg/kg to 0.4 μg/kg in different matrixes. The mean recoveries of propisochlor at three levels (0.005, 0.01 and 0.05 mg/kg) were in the range of 73.7-94.9% with intra-day relative standard deviations (RSD) of 1.1-13.9% and inter-day RSDR of 3.3-12.7%. This method is suitable for routine analysis of propisochlor under field conditions. The half-lives of propisochlor in rice stalks, water and soil were 1.7, 1.5 and 2.3 days in Hunan, 5.7, 1.0 and 1.9 days in Anhui and 4.8, 1.0 and 3.1 days in Guangxi.
Wu, Xiaohu,Xu, Jun,Liu, Xingang,Dong, Fengshou,Wu, Yanbing,Zhang, Ying,Zheng, Yongquan Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
A simple, quick and reliable analytical method for the confirmation and quantification of propisochlor was developed. The propisochlor was extracted from water, soil and rice (stalks, rice and hull) matrices using acetonitrile, and cleaned up with primary secondary amine and determined by UPLC-MS/MS. The LODs of propisochlor ranged from 0.03 ${\mu}g/kg$ to 0.12 ${\mu}g/kg$, while the LOQs ranged from 0.1 ${\mu}g/kg$ to 0.4 ${\mu}g/kg$ in different matrixes. The mean recoveries of propisochlor at three levels (0.005, 0.01 and 0.05 mg/kg) were in the range of 73.7-94.9% with intra-day relative standard deviations (RSD) of 1.1-13.9% and inter-day $RSD_R$ of 3.3-12.7%. This method is suitable for routine analysis of propisochlor under field conditions. The half-lives of propisochlor in rice stalks, water and soil were 1.7, 1.5 and 2.3 days in Hunan, 5.7, 1.0 and 1.9 days in Anhui and 4.8, 1.0 and 3.1 days in Guangxi.
A Probabilistic Approach for Three-Dimensional Variation Analysis in Aero-engine Rotors Assembly
Siyi Ding,Yuhang He,Xiaohu Zheng 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.5
Rotor assembly is a core tache in the whole process of aero-engine manufacturing. Preventing out-of-tolerance of concentricity is one of the primary tasks. Conventional assembly approaches are based on a manual test with the dial indicator, depending on experience appraises, which lack systematic and quantitative precision design theory. As a result, two issues need to be solved: the modeling problem of complicated geometric variations in three-dimensions, as well as the abnormal distribution of ubiquitous actual deviations. This work attempts to propose a novel probabilistic approach for three-dimensional variation analysis in rotor assembly. Based on rotor’s revolving characteristics and multistage stacking process, Jacobian–Torsor model is adopted to establish the variation propagation, and Pearson distribution family is used to derive the probability density function, which can quickly determine the variation distribution pattern and efficiently perform statistical variation analysis. A real case of mechanical assemblies consisting of revolving axisymmetric components is concerned. The results show that the suggested method has a similar accuracy, but much higher efficiency than conventional methods. Calculations agree with the experimentations, and the probability distribution type of the part’s variation has an appreciable impact on the final assembly precision.
Fuzhen Chen,Hanqiao Jiang,Xiaohu Bai,Wei Zheng 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
Sodium metaborate, a novel alkali, is introduced into alkali/surfactant/polymer (ASP) flooding to solve the negative effects caused by conventional alkalis. Sodium metaborate can reduce the adsorption loss of the surfactant as well as the interfacial tension (IFT). Weak alkali sodium metaborate causes less viscosity reduction compared with strong alkalis. Scale precipitation study shows that sodium metaborate can be effective to avoid the scale precipitation damage. Study results indicate that sodium metaborate result in the highest oil recovery of 56% compared with sodium carbonate and sodium hydroxide, and at the same time avoid the problems caused by conventional alkalis.