Error modelling and compensating technology is an effective method to improve the processing precision.The position and orientation deviation of workpiece is caused by the fixing and manufacturing errors of the fixtur...Error modelling and compensating technology is an effective method to improve the processing precision.The position and orientation deviation of workpiece is caused by the fixing and manufacturing errors of the fixture.How to reduce the position and orientation deviation of workpiece has become a technical problem of improving the processing quality of workpiece.In order to increase machining accuracy,an implementation scheme of fixture system comprehensive errors（FSCE） compensation is proposed.A FSCE parameter model is established by analyzing the influence of contact points on the position and orientation of workpiece.Meanwhile,a parameter identification method for FSCE parameter model is presented by using the 3-2-1 deterministic positioning fixture,which determines the model parameters.Moreover,a FSCE compensation model is formulated to study the compensation value of the cutting position.By using RenishawOMP60 Probe and combining vertical machining centre（SKVH850） equipment with SKY2001 Open CNC System,on-machine verification system（OMVS） is built to measure FSCE successfully.The processing error can be reduced by analyzing the cutting position of the tool with the homogeneous transformation of space coordinate system.Finally,the compensation experiment of real time errors is conducted,and the cylindricality and perpendicularity errors of hole surface are reduced by 30.77% and 28.57%,respectively.This paper provides a new way of realizing the compensation of FCSE,which can improve the machining accuracy of workpiece largely.展开更多
A searching-machining system of RL & SM (Rapid Location and State Memory) universal fixture is here introduced, and the concept of rapid searching technology and manufacturing information transformation is then de...A searching-machining system of RL & SM (Rapid Location and State Memory) universal fixture is here introduced, and the concept of rapid searching technology and manufacturing information transformation is then described, with the appropriate control methods and key techniques for its realization being proposed and also practically realized. Theoretical analysis and experimental results show that the proposed idea and methods are feasible to serve as in the practical application of the RL & SM system.展开更多
A new fixture system-Rapid Location and State Memory (RL&SM) fixture system is presented.It is based on RFPE technique.In which a new method-adaptable location system is used to locating arbitrarily shapedpart.It ...A new fixture system-Rapid Location and State Memory (RL&SM) fixture system is presented.It is based on RFPE technique.In which a new method-adaptable location system is used to locating arbitrarily shapedpart.It solves the problems of part location,stock driftand accessibility of all sides of the part in machining.Any part can be machined entirely in a single setup by an appropriate machine tool.RL&SM fixture system consists of four parts:state memory,setup,data measure and information handling.The principle,components and work process of it are discussed,and some of the key techniques for industrialization are also presented.Keywords:Universal fixture,Rapid location,State memo-展开更多
The welding fixtures are the most important devices for an auto body welding assembly line. The current special fixtures used by many automotive manufactures are only fit for one or several specific welding processes,...The welding fixtures are the most important devices for an auto body welding assembly line. The current special fixtures used by many automotive manufactures are only fit for one or several specific welding processes, and the dimensional problem in the circle due to several variation sources accumulation has no adjustment. The active error compensating welding fixture system for auto body is designed and manufactured. The detecting model, coordinate transformation model, and adjusting model based on auto body coordinate system are presented. The dowel pin modular design is adopted in the structure of the fixture to suit different workpieces with some similar characteristics. The online detection and adaptive control system using eddy current sensors and adaptive adjusting devices is analyzed. Three kinds of the left rear wheel covers SGM60 are selected to test workpieces of the developed system, and the active error compensating experiments are performed in the lab for many times. Test results show the validity of mechanism reconfigurations, on-line detections and error compensations of the developed welding fixture.展开更多
The computer numerical control（CNC） system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are pr...The computer numerical control（CNC） system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are presented and analyzed. The hardware and software architecture and implementation of CNC system are pro- posed. The flexible fixture mechanism is described using configuration parameters. According to the parameters, the CNC system automatically generates the control feature and the human machine interface （HMI） operation function. The CNC system is implemented in a flexible fixture for skin-strlnger assembly, and results show the effectiveness of the system.展开更多
An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing lit...An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.展开更多
This work aims to improve the setup of an electrodynamic triaxial shaker prototype with respect to its usability for the automotive industry.Triaxial shakers being capable of meeting the corresponding requirements are...This work aims to improve the setup of an electrodynamic triaxial shaker prototype with respect to its usability for the automotive industry.Triaxial shakers being capable of meeting the corresponding requirements are not available as standard test equipment.Modifications on the fixture have to be conducted in order to ensure an effective control.The first part of the work is the qualitative description of the system behavior.Therefore,the shaker is treated as a black box.The second part is the modification of the test fixture in order to handle the resonances of the shaker,which is elementary for its usage.A setup is found,that improves testing within the desired frequency range.Thereby,acceleration levels are considered as well as excitation phases and coherences.The proposed setup is used for an exemplary specimen with two different control scenarios.Conclusions are then drawn about the usage of triaxial shakers.展开更多
A computer aided design system of welding fixture (called WFCAD system) is introduced in this paper. The microcomputer graphics software AutoCAD has been used as the supporting software of WFCAD system. By means of pr...A computer aided design system of welding fixture (called WFCAD system) is introduced in this paper. The microcomputer graphics software AutoCAD has been used as the supporting software of WFCAD system. By means of programming, 2-D and 3-D parameterized graphic libraries of components of welding fixture are established. With the aid of AutoCAD ' s advanced development system (ADS), menus and dialogs are constructed for convenient use of graphic library, and it also makes the system has a good man-machine interface.展开更多
There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to...There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.展开更多
Analyzed the issues of stability of workpiece during clamping and machining. Discussed classification of the stability problem according to the forces acting on the part in the commonly used machining processes; gave ...Analyzed the issues of stability of workpiece during clamping and machining. Discussed classification of the stability problem according to the forces acting on the part in the commonly used machining processes; gave the methods of calculating clamping force and measures to guarantee the stability of workpiece in the feature-based fixture planning design system.展开更多
Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology ...Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology of the lever workpiece,and the workpiece is accurately positioned and tightened under the action of the special fixture.Efficient machining of the workpiece can be achieved by using a drill template.The fixture not only has the advantages of high production efficiency,low cost and high life,but also effectively improves the processing technology of the workpiece,and has certain reference value for the subsequent fixture improvement design.展开更多
This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and worki...This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.展开更多
The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in...Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in the adaptive CNC machining process.Adaptive CNC machining technology is first analyzed,and new fixture-evaluation criteria and methods to evaluate the adaptive CNC machining process fixture design are built.Second,a machining fixture is designed and manufactured after analyzing its positioning scheme,clamping scheme,materials(PEEK-GF30),and structure characteristics.Finally,the designed fixture is analyzed by FEA and experimentally verified by a cutting experiment.The results show that the deformation of the blade is an overall rigid-body displacement,the main deformation of the blade-fixture system occurs on the four clamping heads,and this fixture can effectively protect the blade from local deformation.The proposed clamping-sequence method reliably and effectively controls the local maximum deformation of the blade.The system stiffness is increased by 20 Hz,with each clamping force increased by 200 N.Both high-and low-frequency displacement in roughing milling or finishing milling are acceptable relative to the accuracy demand of blade machining.This fixture and an adaptive CNC machining process can achieve high accuracy in blade manufacturing.展开更多
'N-2-1' principle is widely recognized in the fixture design for deformablesheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixturedesign. However, little research is d...'N-2-1' principle is widely recognized in the fixture design for deformablesheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixturedesign. However, little research is done on how to determine the positions and the number of Nlocators. In practice, the N locators are frequently designed from experience, which is oftenunsatisfactory for achieving the precision requirement in fixture design. A new method to lay outthe N locators for measuring fixture of deformable sheet metal workpiece is presented, given thefixed number of A'. Finite-element method is used to model and analysis the deformation of differentlocator layouts. A knowledge based genetic algorithm (KBGA) is applied to identify the optimumlocator layout for measuring fixture design. An example of a door outer is used to verify theoptimization approach.展开更多
Based on the features of the design and assembly of rnodular fixtures, a new design system which combines intelligent selection of elements and interactive assembly is presented.Using the fixture design datum, the sys...Based on the features of the design and assembly of rnodular fixtures, a new design system which combines intelligent selection of elements and interactive assembly is presented.Using the fixture design datum, the system can automatically select elements,and can interactively assemble together these elements based on AutoCAD. An example is given to illustrate it.展开更多
An automotive body is composed of compliant sheet metal parts.Fast and exactly diagnosing variation sources is very important when assembly variations happen.This paper proposes a diagnosis method of multi fixture var...An automotive body is composed of compliant sheet metal parts.Fast and exactly diagnosing variation sources is very important when assembly variations happen.This paper proposes a diagnosis method of multi fixture variations based on the variation model of compliant sheet metal assembly.The assembly variation model is obtained by using the method of influence coefficients(MIC) and considering the manufacturing variations of compliant parts and multi fixture variations.The measurement point variations induced by part manufacturing variations are firstly removed from the measurement data.The variation patterns of multi fixture variations are constructed by column vectors of fixture variation sensitivity matrix.This method is proved to be feasible for exactly diagnosing the fixture variations and has higher diagnosis efficiency than designated component analysis(DCA).展开更多
A numerical model is established by Abaqus software for superalloy during tungsten inert gas （TIG） welding with welding fixture to simulate the weld temperature filed, stress and strain field, and weld plate＇s hori...A numerical model is established by Abaqus software for superalloy during tungsten inert gas （TIG） welding with welding fixture to simulate the weld temperature filed, stress and strain field, and weld plate＇s horizontal trasnsveral shift. The clamp force perpendicular to the weld plate varying with welding time was analyzed. The maximum clamp force during welding process was calculated. Under the condition of insufficient of clamping force, a half or one third of the maximum clamp force for example, the weld plate＇s horizontal transversal displacement could happen and also be computed.展开更多
Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout...Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout to minimize the manufacturing deformation.Firstly,a topological optimization model that takes the stiffness of ATWC as the objective function and the volume of the locating structure as the constraint is established.Secondly,ATWC and the locating structure are regarded as an integrated entity,and the variable-density method based topological optimization approach is adopted for the optimization of the locating structure using ABAQUS topology optimization module(ATOM).Thirdly,through a subsequent model reconstruction referring to the obtained topological structure,the optimal fixture locating layout is achieved.Finally,a case study is conducted to verify the proposed method and the comparison results with firefly algorithm(FA)coupled with finite element analysis(FEA)indicate that the number and positions of the locators for ATWC can be optimized simultaneously and successfully by the proposed topological optimization model.展开更多
Based on an example of its typical structure, the concept of modular fixture structure module is presented, and the structure module system of modular fixture is summarized. Then the parametric design of structure is ...Based on an example of its typical structure, the concept of modular fixture structure module is presented, and the structure module system of modular fixture is summarized. Then the parametric design of structure is discussed, and its advantages are also emphasized.Furthermore, some specific methods are provided, such as the selection of fixture components, the determination and input of parameters, drawing representative model,and the creation of drawing. Finally an applied example of strcture parametric design is presented.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50975200)National Key Technologies R & D Programmer of China (Grant No. 2009ZX04014-021)
文摘Error modelling and compensating technology is an effective method to improve the processing precision.The position and orientation deviation of workpiece is caused by the fixing and manufacturing errors of the fixture.How to reduce the position and orientation deviation of workpiece has become a technical problem of improving the processing quality of workpiece.In order to increase machining accuracy,an implementation scheme of fixture system comprehensive errors（FSCE） compensation is proposed.A FSCE parameter model is established by analyzing the influence of contact points on the position and orientation of workpiece.Meanwhile,a parameter identification method for FSCE parameter model is presented by using the 3-2-1 deterministic positioning fixture,which determines the model parameters.Moreover,a FSCE compensation model is formulated to study the compensation value of the cutting position.By using RenishawOMP60 Probe and combining vertical machining centre（SKVH850） equipment with SKY2001 Open CNC System,on-machine verification system（OMVS） is built to measure FSCE successfully.The processing error can be reduced by analyzing the cutting position of the tool with the homogeneous transformation of space coordinate system.Finally,the compensation experiment of real time errors is conducted,and the cylindricality and perpendicularity errors of hole surface are reduced by 30.77% and 28.57%,respectively.This paper provides a new way of realizing the compensation of FCSE,which can improve the machining accuracy of workpiece largely.
文摘A searching-machining system of RL & SM (Rapid Location and State Memory) universal fixture is here introduced, and the concept of rapid searching technology and manufacturing information transformation is then described, with the appropriate control methods and key techniques for its realization being proposed and also practically realized. Theoretical analysis and experimental results show that the proposed idea and methods are feasible to serve as in the practical application of the RL & SM system.
基金Supported by national high technology development plan(863-511-943-010)
文摘A new fixture system-Rapid Location and State Memory (RL&SM) fixture system is presented.It is based on RFPE technique.In which a new method-adaptable location system is used to locating arbitrarily shapedpart.It solves the problems of part location,stock driftand accessibility of all sides of the part in machining.Any part can be machined entirely in a single setup by an appropriate machine tool.RL&SM fixture system consists of four parts:state memory,setup,data measure and information handling.The principle,components and work process of it are discussed,and some of the key techniques for industrialization are also presented.Keywords:Universal fixture,Rapid location,State memo-
基金Shanghai Leading Academic Discipline Project,China(No.B602)Patent Second Development Project of Science and Technology Commission of Shanghai Municipality,China(No.05dz52038)
文摘The welding fixtures are the most important devices for an auto body welding assembly line. The current special fixtures used by many automotive manufactures are only fit for one or several specific welding processes, and the dimensional problem in the circle due to several variation sources accumulation has no adjustment. The active error compensating welding fixture system for auto body is designed and manufactured. The detecting model, coordinate transformation model, and adjusting model based on auto body coordinate system are presented. The dowel pin modular design is adopted in the structure of the fixture to suit different workpieces with some similar characteristics. The online detection and adaptive control system using eddy current sensors and adaptive adjusting devices is analyzed. Three kinds of the left rear wheel covers SGM60 are selected to test workpieces of the developed system, and the active error compensating experiments are performed in the lab for many times. Test results show the validity of mechanism reconfigurations, on-line detections and error compensations of the developed welding fixture.
文摘The computer numerical control（CNC） system is suited to control varied types of flexible fixtures in aircraft component manufacturing and assembly. The mechanisms and control requirements of flexible fixtures are presented and analyzed. The hardware and software architecture and implementation of CNC system are pro- posed. The flexible fixture mechanism is described using configuration parameters. According to the parameters, the CNC system automatically generates the control feature and the human machine interface （HMI） operation function. The CNC system is implemented in a flexible fixture for skin-strlnger assembly, and results show the effectiveness of the system.
基金Supported by National Natural Science Foundation of China(Grant No.52005371)Shanghai Municipal Natural Science Foundation of China(Grant No.22ZR1463900)+1 种基金Fundamental Research Funds for the Central Universities of China(Grant No.22120220649)State Key Laboratory of Mechanical System and Vibration of China(Grant No.MSV202318).
文摘An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.
文摘This work aims to improve the setup of an electrodynamic triaxial shaker prototype with respect to its usability for the automotive industry.Triaxial shakers being capable of meeting the corresponding requirements are not available as standard test equipment.Modifications on the fixture have to be conducted in order to ensure an effective control.The first part of the work is the qualitative description of the system behavior.Therefore,the shaker is treated as a black box.The second part is the modification of the test fixture in order to handle the resonances of the shaker,which is elementary for its usage.A setup is found,that improves testing within the desired frequency range.Thereby,acceleration levels are considered as well as excitation phases and coherences.The proposed setup is used for an exemplary specimen with two different control scenarios.Conclusions are then drawn about the usage of triaxial shakers.
文摘A computer aided design system of welding fixture (called WFCAD system) is introduced in this paper. The microcomputer graphics software AutoCAD has been used as the supporting software of WFCAD system. By means of programming, 2-D and 3-D parameterized graphic libraries of components of welding fixture are established. With the aid of AutoCAD ' s advanced development system (ADS), menus and dialogs are constructed for convenient use of graphic library, and it also makes the system has a good man-machine interface.
基金Supported by National Natural Science Foundation of China(Grant No.52005371)Shanghai Pujiang Program of China(Grant No.2020PJD071)+1 种基金Shanghai Municipal Natural Science Foundation of China(Grant No.22ZR1463900)Fundamental Research Funds for the Central Universities of China.
文摘There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.
文摘Analyzed the issues of stability of workpiece during clamping and machining. Discussed classification of the stability problem according to the forces acting on the part in the commonly used machining processes; gave the methods of calculating clamping force and measures to guarantee the stability of workpiece in the feature-based fixture planning design system.
基金supported by the Henan Natural Science Foundation (No.222300420168)the Natural Science Foundation of Henan Polytechnic University (B2021-31)Fundamental Research Funds for the Universities of Henan Province (No.NSFRF220415).
文摘Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology of the lever workpiece,and the workpiece is accurately positioned and tightened under the action of the special fixture.Efficient machining of the workpiece can be achieved by using a drill template.The fixture not only has the advantages of high production efficiency,low cost and high life,but also effectively improves the processing technology of the workpiece,and has certain reference value for the subsequent fixture improvement design.
文摘This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金supported in part by Xi’an Aero-Engine(Group)Ltd.National Key Scientific Instrument and Equipment Development Project(2016YFF0101900)+1 种基金National Natural Science Foundation of China(Grant 51575310)Beijing Municipal Natural Science Foundation(Grant 3162014)。
文摘Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in the adaptive CNC machining process.Adaptive CNC machining technology is first analyzed,and new fixture-evaluation criteria and methods to evaluate the adaptive CNC machining process fixture design are built.Second,a machining fixture is designed and manufactured after analyzing its positioning scheme,clamping scheme,materials(PEEK-GF30),and structure characteristics.Finally,the designed fixture is analyzed by FEA and experimentally verified by a cutting experiment.The results show that the deformation of the blade is an overall rigid-body displacement,the main deformation of the blade-fixture system occurs on the four clamping heads,and this fixture can effectively protect the blade from local deformation.The proposed clamping-sequence method reliably and effectively controls the local maximum deformation of the blade.The system stiffness is increased by 20 Hz,with each clamping force increased by 200 N.Both high-and low-frequency displacement in roughing milling or finishing milling are acceptable relative to the accuracy demand of blade machining.This fixture and an adaptive CNC machining process can achieve high accuracy in blade manufacturing.
基金This project is supported by Overseas Young Scientists Cooperation of National Natural Science Foundation of China (No.59958204) National Natural Science Foundation of China (No.50175071). :
文摘'N-2-1' principle is widely recognized in the fixture design for deformablesheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixturedesign. However, little research is done on how to determine the positions and the number of Nlocators. In practice, the N locators are frequently designed from experience, which is oftenunsatisfactory for achieving the precision requirement in fixture design. A new method to lay outthe N locators for measuring fixture of deformable sheet metal workpiece is presented, given thefixed number of A'. Finite-element method is used to model and analysis the deformation of differentlocator layouts. A knowledge based genetic algorithm (KBGA) is applied to identify the optimumlocator layout for measuring fixture design. An example of a door outer is used to verify theoptimization approach.
文摘Based on the features of the design and assembly of rnodular fixtures, a new design system which combines intelligent selection of elements and interactive assembly is presented.Using the fixture design datum, the system can automatically select elements,and can interactively assemble together these elements based on AutoCAD. An example is given to illustrate it.
基金the National Natural Science Foundation of China (No. 50705056)the National High Technology Research and Development Program (863) of China (No.2006AA04Z148)
文摘An automotive body is composed of compliant sheet metal parts.Fast and exactly diagnosing variation sources is very important when assembly variations happen.This paper proposes a diagnosis method of multi fixture variations based on the variation model of compliant sheet metal assembly.The assembly variation model is obtained by using the method of influence coefficients(MIC) and considering the manufacturing variations of compliant parts and multi fixture variations.The measurement point variations induced by part manufacturing variations are firstly removed from the measurement data.The variation patterns of multi fixture variations are constructed by column vectors of fixture variation sensitivity matrix.This method is proved to be feasible for exactly diagnosing the fixture variations and has higher diagnosis efficiency than designated component analysis(DCA).
基金supported by the National Natural Science Foundation of China(Grant No.51275496)
文摘A numerical model is established by Abaqus software for superalloy during tungsten inert gas （TIG） welding with welding fixture to simulate the weld temperature filed, stress and strain field, and weld plate＇s horizontal trasnsveral shift. The clamp force perpendicular to the weld plate varying with welding time was analyzed. The maximum clamp force during welding process was calculated. Under the condition of insufficient of clamping force, a half or one third of the maximum clamp force for example, the weld plate＇s horizontal transversal displacement could happen and also be computed.
基金supported by the National Natural Science Foundation of China(No.51375396)the Shaanxi Science and Technology Innovation Project Plan,China(No.2016KTCQ01-50)
文摘Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout to minimize the manufacturing deformation.Firstly,a topological optimization model that takes the stiffness of ATWC as the objective function and the volume of the locating structure as the constraint is established.Secondly,ATWC and the locating structure are regarded as an integrated entity,and the variable-density method based topological optimization approach is adopted for the optimization of the locating structure using ABAQUS topology optimization module(ATOM).Thirdly,through a subsequent model reconstruction referring to the obtained topological structure,the optimal fixture locating layout is achieved.Finally,a case study is conducted to verify the proposed method and the comparison results with firefly algorithm(FA)coupled with finite element analysis(FEA)indicate that the number and positions of the locators for ATWC can be optimized simultaneously and successfully by the proposed topological optimization model.
文摘Based on an example of its typical structure, the concept of modular fixture structure module is presented, and the structure module system of modular fixture is summarized. Then the parametric design of structure is discussed, and its advantages are also emphasized.Furthermore, some specific methods are provided, such as the selection of fixture components, the determination and input of parameters, drawing representative model,and the creation of drawing. Finally an applied example of strcture parametric design is presented.
