This paper makes a study of the cause of manufacturing fault,develops the and/or- fault-tree of manufacturing quality fault for MC,and presents a new concept of faint manufacturing quality fault(FMQF)and the decision ...This paper makes a study of the cause of manufacturing fault,develops the and/or- fault-tree of manufacturing quality fault for MC,and presents a new concept of faint manufacturing quality fault(FMQF)and the decision making tree with which the fault of manufacturing system would be found out from FMQF.An approach to identification of FMQF,based on fuzzy set theory,is presented,which can be used for estimating the status of equipment with the deviation of control charts.Based on the study above,an expert system for the flexible manufacturing system's FMQF detection and prediction is built.展开更多
Accurate quantification of external force is the key to improve the high-precision hemming of autobody closure panels.However,the mechanism of external force on forming quality of complex contour sheet metal with adhe...Accurate quantification of external force is the key to improve the high-precision hemming of autobody closure panels.However,the mechanism of external force on forming quality of complex contour sheet metal with adhesive is not clear subjected to geometric curvature and materials.In the present study,taking the curved edge aluminum sheet as the research object,SPH(smooth particle hydrodynamics)is introduced to simulate the viscous adhesive,and the SPH-FEM(Finite element method)coupling model of adhesive and panels considering the viscosity-pressure effect is established.The numerical simulation of the roller hemming process is carried out,then the validity and reliability of the proposed method are verified by measuring the external force in real time using triaxial force sensor.The multi-step forming process and the effect of external force on the roll in/out,surface wave and plastic strain of aluminum alloy sheet under the viscosity-pressure effect are studied,and the relationship between process parameters and external force is discussed.Results show that the coupling SPH-FEM model can well reflect the hemming process of curved edge structure.The normal force is about 2–3 times of the tangential force in the pre and final hemming process.Compared with the case without adhesive,the surface wave of flange part of the hemming with adhesive is slightly larger.The normal force and the tangential force increase about 90 N and 30 N respectively,when the height increases by 1 mm.It provides an important basis for the accurate control of hemming trajectory and the improvement of manufacturing quality of autobody closure panels.展开更多
Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are ...Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P＆O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation（U-P＆O）,as a part of the evaluating result of P＆O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P＆O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P＆O in measurement assisted alignment.The geometrical and algebraical connotations of U-P＆O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P＆O is given,and the effect factors and characteristics of U-P＆O are discussed.Finally,U-P＆O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology.展开更多
文摘This paper makes a study of the cause of manufacturing fault,develops the and/or- fault-tree of manufacturing quality fault for MC,and presents a new concept of faint manufacturing quality fault(FMQF)and the decision making tree with which the fault of manufacturing system would be found out from FMQF.An approach to identification of FMQF,based on fuzzy set theory,is presented,which can be used for estimating the status of equipment with the deviation of control charts.Based on the study above,an expert system for the flexible manufacturing system's FMQF detection and prediction is built.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975416 and 51275359)。
文摘Accurate quantification of external force is the key to improve the high-precision hemming of autobody closure panels.However,the mechanism of external force on forming quality of complex contour sheet metal with adhesive is not clear subjected to geometric curvature and materials.In the present study,taking the curved edge aluminum sheet as the research object,SPH(smooth particle hydrodynamics)is introduced to simulate the viscous adhesive,and the SPH-FEM(Finite element method)coupling model of adhesive and panels considering the viscosity-pressure effect is established.The numerical simulation of the roller hemming process is carried out,then the validity and reliability of the proposed method are verified by measuring the external force in real time using triaxial force sensor.The multi-step forming process and the effect of external force on the roll in/out,surface wave and plastic strain of aluminum alloy sheet under the viscosity-pressure effect are studied,and the relationship between process parameters and external force is discussed.Results show that the coupling SPH-FEM model can well reflect the hemming process of curved edge structure.The normal force is about 2–3 times of the tangential force in the pre and final hemming process.Compared with the case without adhesive,the surface wave of flange part of the hemming with adhesive is slightly larger.The normal force and the tangential force increase about 90 N and 30 N respectively,when the height increases by 1 mm.It provides an important basis for the accurate control of hemming trajectory and the improvement of manufacturing quality of autobody closure panels.
基金support of National Natural Science Foundation of China (No.50905010)Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing (No.SAMC12-JS-15-044)
文摘Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P＆O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation（U-P＆O）,as a part of the evaluating result of P＆O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P＆O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P＆O in measurement assisted alignment.The geometrical and algebraical connotations of U-P＆O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P＆O is given,and the effect factors and characteristics of U-P＆O are discussed.Finally,U-P＆O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology.
