In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult ras...In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult rasonic vibration cutting device to the traditional lathe. The influence rule of the cutting condition on the surface roughness was put forward, which was drawn by comparing the ultrasonic cutting with the common cutting by use of the cemen ted carbide tool and the polycrystalline diamond (PCD) tool. The test results sh owed that the ultrasonic cutting performs better than the common cutting in the same condition. According to the test results analyzing, the surface characteriz ation is influenced clearly by the rigidity of the acoustic system and the machi ne tool, as well the setting height of the tool tip. Otherwise, the dense regula r low frequency vibration ripples will be scraped on the machined surface. When the tool tip is set higher than the rotating center of the work piece by three t imes of the amplitude of ultrasonic vibration, the vibration ripples behave alig ht; they turn light and shade alternatively when the tool tip is lower than the rotating center of the work piece by three times of the amplitude of ultrasonic vibration. According to the test result analyzing, the following conclusions are put forward: 1) The surface roughness in ultrasonic cutting is better than that in common cutting. Under a one third critical cutting velocity, the value of th e surface roughness in ultrasonic cutting rise slightly along with the cutting v elocity, while in common cutting it decreases contrast to the cutting velocity; the curves of the surface roughness in ultrasonic cutting and common cutting see m to be alike, both increase along with the feed rate and the cutting depth, but the value in ultrasonic cutting is smaller in the same condition.2) The influen ce of the coolant on the surface roughness cannot be ignored. The kerosene can b e employed to improve the surface roughness in ultrasonic machining.3) In ultras onic cutting process of aluminum alloy ultra-thin wall work piece, the PCD tool performs better than the cemented carbide tools.4) The vibration ripples result from the not enough rigidity of the acoustic system and the improper setting he ight of the tool tip. The departure of the tool tip from the rotating center of the work piece to some extent causes the vibration ripples on the machined surfa ce.展开更多
In order to optimize the spares configuration project at different stages during the life cycle, the factor of time is considered to relax the assumption of the spares steady demand in multi-echelon technique for reco...In order to optimize the spares configuration project at different stages during the life cycle, the factor of time is considered to relax the assumption of the spares steady demand in multi-echelon technique for recoverable item control (METRIC) theory. According to the method of systems analysis, the dynamic palm theorem is introduced to establish the prediction model of the spares demand rate, and its main influence factors are analyzed, based on which, the spares support effectiveness evaluation index system is studied, and the system optimization-oriented spares dynamic configuration method for multi-echelon multi-indenture system is proposed. Through the analysis of the optimization algorithm, the layered marginal algorithm is designed to improve the model calculation efficiency. In a given example, the multi-stage spares configuration project during its life cycle is gotten, the research result conforms to the actual status, and it can provide a new way for the spares dynamic optimization.展开更多
A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The alumi...A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.展开更多
In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed thr...In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.展开更多
In equipment integrated logistics support(ILS), the supply capability of spare parts is a significant factor. There are lots of depots in the traditional support system, which makes too many redundant spare parts and ...In equipment integrated logistics support(ILS), the supply capability of spare parts is a significant factor. There are lots of depots in the traditional support system, which makes too many redundant spare parts and causes high cost of support. Meanwhile,the inconsistency among depots makes it difficult to manage spare parts. With the development of information technology and transportation, the supply network has become more efficient. In order to further improve the efficiency of supply-support work and the availability of the equipment system, building a system of one centralized depot with multiple depots becomes an appropriate way.In this case, location selection of the depots including centralized depots and multiple depots becomes a top priority in the support system. This paper will focus on the location selection problem of centralized depots considering ILS factors. Unlike the common location selection problem, depots in ILS require a higher service level. Therefore, it becomes desperately necessary to take the high requirement of the mission into account while determining location of depots. Based on this, we raise an optimal depot location model. First, the expected transportation cost is calculated.Next, factors in ILS such as response time, availability and fill rate are analyzed for evaluating positions of open depots. Then, an optimization model of depot location is developed with the minimum expected cost of transportation as objective and ILS factors as constraints. Finally, a numerical case is studied to prove the validity of the model by using the genetic algorithm. Results show that depot location obtained by this model can guarantee the effectiveness and capability of ILS well.展开更多
Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study ...Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study the friction and wear behavior of parts made of newly developed Nylon6-Fe composite material by FDM. This work also involves the comparison of the friction and wear characteristics of the Nylon6-Fe composite with the existing acrylonitrile butadiene styrene(ABS) filament of the FDM machine. This Is carried out on the pin on disk setup by varying the load(5, 10, 15 and 20 N) and speed(200 and 300 r/min). It is concluded that the newly developed composite is highly wear resistant and can be used in industrial applications where wear resistance is of paramount importance. Morphology of the surface in contact with the Nylon6-Fe composite and ABS is also carried out.展开更多
By adopting the parameterized designing method of f ea ture assembled and feature unit, for the feature of non-conventional type parts , such as welding box and bearer, by use of Visual C++ and AutoCAD a s soft tools,...By adopting the parameterized designing method of f ea ture assembled and feature unit, for the feature of non-conventional type parts , such as welding box and bearer, by use of Visual C++ and AutoCAD a s soft tools, the system can successfully carry out the basic function of featur e assembled, the processing of two-dimensional figure, the building of three-d imensional feature, the automatic producing of technical papers, and so on. The thoughts and design methods of this system can be served as the preference to CA D/CAPP integrated for othernon-conventional type parts. For non-conventional parts, its feature is too much, so the parameter is much. By adopting interactive entry for graphic parameter, under the control of main c ontrol module, through inputting the feature parameter and calling the feature g raphic unit, the function for modeling is completed. To reduce input of feature parameter, the description of position feature is adopted in the feature descrip tion of non-conventional parts, that is, fix position is constraint through str ucture and dimension of non-conventional parts. In such a manner, the assembled process has been transformed the coordinate conversion process, and this is ver y important in the production of three-dimensional graphics. In the one hand, b y calling the feature of parts in the library of feature-graphic unit, the two -dimensional DXF file and three-dimensional SCR file are automatically produce d in AutoCAD. On the other hand, by calling the rules and standard operational s equences in the technologic knowledge base, through inferring of inference engin e, the assembled sequence of non-conventional parts and welding sequences are a utomatically produced. The two aspects constitute overall design philosophy for system. So the CAD/CAPP integration of feature-assembled for non-conventio nal parts are completed. The principle of dividing feature is based on the thought of group technology, t hat is, according to the function feature of parts. The feature-assembled p arameterized design method is to divide the parts into many feature-units, acco rding to the structure, function, and secondary feature, and the each unit is in teractively produced, so the whole part is assembled gradually. At the same time , to display the sequences which deviser chooses varied features, hidden feature code is adopted. The feature-unit parameterized design method is to assemble dimension, margin tolerance and fitting-in, and surface roughness into one unit that it becomes a fixed structure. However big it is, it could be added to or taken off like a ba sic feature-unit.By adopting above-mentioned methods, the module of parts is e stablished. Under the integrated environment, according to basic construct of expert system, CAPP system is made up of three sectionsdynamic database (document-view ), knowledge library and inference engine. Dynamic database is served as storing initialized and middle information as well as ultimate design result. The knowl edge library is composed of static database, rule set, and standard welding proc ess library.展开更多
Numerical methods for Differential-Algebraic systems with discontinuous right-hand sides is discussed. A class of continuous Rosenbrock methods are constructed, and numerical experiments show that the continuous Rosen...Numerical methods for Differential-Algebraic systems with discontinuous right-hand sides is discussed. A class of continuous Rosenbrock methods are constructed, and numerical experiments show that the continuous Rosenbrock methods are effective. Applying the methods, a fast and high-precision numerical algorithm is given to deal with typical discontinuous parts, which occur frequently in differential-algebraic systems(DAS).展开更多
CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidificati...CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment casting can be acquired without metal die in short time. These can reduce period and cost greatly of complex superalloy parts development of engine. The key processes of CA investment casting were discussed. The accuracy of model translation should match that of RP system. Choice of RP material, surface polishing, sintering parameter plays important role in RP process. Other processes, like solidification simulating and optimization of gate system were introduced. The conclusion was that complex parts can be produced by CA investment casting with lots of advantages. The accuracy of castings can reach CT5～7,and the smoothness can get Ra3～13 mm. These parts of engines worked well.展开更多
文摘In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult rasonic vibration cutting device to the traditional lathe. The influence rule of the cutting condition on the surface roughness was put forward, which was drawn by comparing the ultrasonic cutting with the common cutting by use of the cemen ted carbide tool and the polycrystalline diamond (PCD) tool. The test results sh owed that the ultrasonic cutting performs better than the common cutting in the same condition. According to the test results analyzing, the surface characteriz ation is influenced clearly by the rigidity of the acoustic system and the machi ne tool, as well the setting height of the tool tip. Otherwise, the dense regula r low frequency vibration ripples will be scraped on the machined surface. When the tool tip is set higher than the rotating center of the work piece by three t imes of the amplitude of ultrasonic vibration, the vibration ripples behave alig ht; they turn light and shade alternatively when the tool tip is lower than the rotating center of the work piece by three times of the amplitude of ultrasonic vibration. According to the test result analyzing, the following conclusions are put forward: 1) The surface roughness in ultrasonic cutting is better than that in common cutting. Under a one third critical cutting velocity, the value of th e surface roughness in ultrasonic cutting rise slightly along with the cutting v elocity, while in common cutting it decreases contrast to the cutting velocity; the curves of the surface roughness in ultrasonic cutting and common cutting see m to be alike, both increase along with the feed rate and the cutting depth, but the value in ultrasonic cutting is smaller in the same condition.2) The influen ce of the coolant on the surface roughness cannot be ignored. The kerosene can b e employed to improve the surface roughness in ultrasonic machining.3) In ultras onic cutting process of aluminum alloy ultra-thin wall work piece, the PCD tool performs better than the cemented carbide tools.4) The vibration ripples result from the not enough rigidity of the acoustic system and the improper setting he ight of the tool tip. The departure of the tool tip from the rotating center of the work piece to some extent causes the vibration ripples on the machined surfa ce.
基金supported by the National Defense Pre-research Project in 13th Five-Year(41404050502)the National Defense Science and Technology Fund of the Central Military Commission(2101140)
文摘In order to optimize the spares configuration project at different stages during the life cycle, the factor of time is considered to relax the assumption of the spares steady demand in multi-echelon technique for recoverable item control (METRIC) theory. According to the method of systems analysis, the dynamic palm theorem is introduced to establish the prediction model of the spares demand rate, and its main influence factors are analyzed, based on which, the spares support effectiveness evaluation index system is studied, and the system optimization-oriented spares dynamic configuration method for multi-echelon multi-indenture system is proposed. Through the analysis of the optimization algorithm, the layered marginal algorithm is designed to improve the model calculation efficiency. In a given example, the multi-stage spares configuration project during its life cycle is gotten, the research result conforms to the actual status, and it can provide a new way for the spares dynamic optimization.
基金Project(U1530138)supported by the National Natural Science Foundation of ChinaProject(A1-8903-17-0103)supported by the Natural Science Foundation of Shanghai Municipal Education Commission,China
文摘A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.
基金Project(51675100)supported by the National Natural Science Foundation of ChinaProject(2016ZX04004008)supported by the National Numerical Control Equipment Major Project of ChinaProject(6902002116)supported by the Foundation of Certain Ministry of China
文摘In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.
基金supported by the Science Challenge Project(TZ2018007)the National Natural Science Foundation of China(71671009+2 种基金 61871013 61573041 61573043)
文摘In equipment integrated logistics support(ILS), the supply capability of spare parts is a significant factor. There are lots of depots in the traditional support system, which makes too many redundant spare parts and causes high cost of support. Meanwhile,the inconsistency among depots makes it difficult to manage spare parts. With the development of information technology and transportation, the supply network has become more efficient. In order to further improve the efficiency of supply-support work and the availability of the equipment system, building a system of one centralized depot with multiple depots becomes an appropriate way.In this case, location selection of the depots including centralized depots and multiple depots becomes a top priority in the support system. This paper will focus on the location selection problem of centralized depots considering ILS factors. Unlike the common location selection problem, depots in ILS require a higher service level. Therefore, it becomes desperately necessary to take the high requirement of the mission into account while determining location of depots. Based on this, we raise an optimal depot location model. First, the expected transportation cost is calculated.Next, factors in ILS such as response time, availability and fill rate are analyzed for evaluating positions of open depots. Then, an optimization model of depot location is developed with the minimum expected cost of transportation as objective and ILS factors as constraints. Finally, a numerical case is studied to prove the validity of the model by using the genetic algorithm. Results show that depot location obtained by this model can guarantee the effectiveness and capability of ILS well.
基金PTU Jalandhar,Manufacturing Research Lab GNDEC,Ludhiana and DST GOI for financial support
文摘Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study the friction and wear behavior of parts made of newly developed Nylon6-Fe composite material by FDM. This work also involves the comparison of the friction and wear characteristics of the Nylon6-Fe composite with the existing acrylonitrile butadiene styrene(ABS) filament of the FDM machine. This Is carried out on the pin on disk setup by varying the load(5, 10, 15 and 20 N) and speed(200 and 300 r/min). It is concluded that the newly developed composite is highly wear resistant and can be used in industrial applications where wear resistance is of paramount importance. Morphology of the surface in contact with the Nylon6-Fe composite and ABS is also carried out.
文摘By adopting the parameterized designing method of f ea ture assembled and feature unit, for the feature of non-conventional type parts , such as welding box and bearer, by use of Visual C++ and AutoCAD a s soft tools, the system can successfully carry out the basic function of featur e assembled, the processing of two-dimensional figure, the building of three-d imensional feature, the automatic producing of technical papers, and so on. The thoughts and design methods of this system can be served as the preference to CA D/CAPP integrated for othernon-conventional type parts. For non-conventional parts, its feature is too much, so the parameter is much. By adopting interactive entry for graphic parameter, under the control of main c ontrol module, through inputting the feature parameter and calling the feature g raphic unit, the function for modeling is completed. To reduce input of feature parameter, the description of position feature is adopted in the feature descrip tion of non-conventional parts, that is, fix position is constraint through str ucture and dimension of non-conventional parts. In such a manner, the assembled process has been transformed the coordinate conversion process, and this is ver y important in the production of three-dimensional graphics. In the one hand, b y calling the feature of parts in the library of feature-graphic unit, the two -dimensional DXF file and three-dimensional SCR file are automatically produce d in AutoCAD. On the other hand, by calling the rules and standard operational s equences in the technologic knowledge base, through inferring of inference engin e, the assembled sequence of non-conventional parts and welding sequences are a utomatically produced. The two aspects constitute overall design philosophy for system. So the CAD/CAPP integration of feature-assembled for non-conventio nal parts are completed. The principle of dividing feature is based on the thought of group technology, t hat is, according to the function feature of parts. The feature-assembled p arameterized design method is to divide the parts into many feature-units, acco rding to the structure, function, and secondary feature, and the each unit is in teractively produced, so the whole part is assembled gradually. At the same time , to display the sequences which deviser chooses varied features, hidden feature code is adopted. The feature-unit parameterized design method is to assemble dimension, margin tolerance and fitting-in, and surface roughness into one unit that it becomes a fixed structure. However big it is, it could be added to or taken off like a ba sic feature-unit.By adopting above-mentioned methods, the module of parts is e stablished. Under the integrated environment, according to basic construct of expert system, CAPP system is made up of three sectionsdynamic database (document-view ), knowledge library and inference engine. Dynamic database is served as storing initialized and middle information as well as ultimate design result. The knowl edge library is composed of static database, rule set, and standard welding proc ess library.
文摘Numerical methods for Differential-Algebraic systems with discontinuous right-hand sides is discussed. A class of continuous Rosenbrock methods are constructed, and numerical experiments show that the continuous Rosenbrock methods are effective. Applying the methods, a fast and high-precision numerical algorithm is given to deal with typical discontinuous parts, which occur frequently in differential-algebraic systems(DAS).
文摘CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment casting can be acquired without metal die in short time. These can reduce period and cost greatly of complex superalloy parts development of engine. The key processes of CA investment casting were discussed. The accuracy of model translation should match that of RP system. Choice of RP material, surface polishing, sintering parameter plays important role in RP process. Other processes, like solidification simulating and optimization of gate system were introduced. The conclusion was that complex parts can be produced by CA investment casting with lots of advantages. The accuracy of castings can reach CT5～7,and the smoothness can get Ra3～13 mm. These parts of engines worked well.
