An ultra-precision servo control system for MWEDM (micro wire electrical discharge machining) based on piezoelectric ceramic motor drivers was developed. The servo discharge detection adopts an average voltage detecti...An ultra-precision servo control system for MWEDM (micro wire electrical discharge machining) based on piezoelectric ceramic motor drivers was developed. The servo discharge detection adopts an average voltage detection method, utilizes statistical methods to analyze the measured data, then controls discharge gap and makes the process more stable. The servo feed system based on DSP microprocessors applies a PID controller with incomplete derivation to reduce overshoot to improve machining accuracy, and also adopts adaptive dead-zone inverse compensation to eliminate dead-zone caused by piezoelectric ceramic motions in low servo feed speed. The simulation results show that the methods proposed in this paper can make the system recover its linearity and converge the dead-zone parameters. It is proved that the method proposed is efficient in solving this problem. Cooperating with a micro energy pulse generator, this equipment’s machining accuracy is smaller than ±0.2 micron, and surface roughness Ra is less than 0.1 micron. Punch die and cavity die (micro gear die, module 100 micron, thickness 3.5 millimeter) have been machined independently in two die steel work-pieces. These pieces can mate very well to work, which shows that the servo control system satisfies the need of MWEDM for high precision micro fabrication.展开更多
Because of the relativity among the parameters, partial least square regression(PLSR)was applied to build the model and get the regression equation. The improved algorithm simplified the calculating process greatly be...Because of the relativity among the parameters, partial least square regression(PLSR)was applied to build the model and get the regression equation. The improved algorithm simplified the calculating process greatly because of the reduction of calculation. The orthogonal design was adopted in this experiment. Every sample had strong representation, which could reduce the experimental time and obtain the overall test data. Combined with the formation problem of gas metal arc weld with big current, the auxiliary analysis technique of PLSR was discussed and the regression equation of form factors (i.e. surface width, weld penetration and weld reinforcement) to process parameters(i.e. wire feed rate, wire extension, welding speed, gas flow, welding voltage and welding current)was given. The correlativity structure among variables was analyzed and there was certain correlation between independent variables matrix X and dependent variables matrix Y. The regression analysis shows that the welding speed mainly influences the weld formation while the variation of gas flow in certain range has little influence on formation of weld. The fitting plot of regression accuracy is given. The fitting quality of regression equation is basically satisfactory.展开更多
The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs...The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.展开更多
Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and...Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and time consuming. In this paper, artificial neural network (ANN) and genetic algorithm (GA) are used together to establish the parameter optimization model. An ANN model which adapts Levenberg-Marquardt algorithm has been set up to represent the relationship between material removal rate (MRR) and input parameters, and GA is used to optimize parameters, so that optimization results are obtained. The model is shown to be effective, and MRR is improved using optimized machining parameters.展开更多
Electrochemical machining（ECM） is one of the important non-traditional machining processes,which is used for machining of difficult-to-machine materials and intricate profiles.Being a complex process,it is very diff...Electrochemical machining（ECM） is one of the important non-traditional machining processes,which is used for machining of difficult-to-machine materials and intricate profiles.Being a complex process,it is very difficult to determine optimal parameters for improving cutting performance.Metal removal rate and surface roughness are the most important output parameters,which decide the cutting performance.There is no single optimal combination of cutting parameters,as their influences on the metal removal rate and the surface roughness are quite opposite.A multiple regression model was used to represent relationship between input and output variables and a multi-objective optimization method based on a non-dominated sorting genetic algorithm-Ⅱ（NSGA-Ⅱ） was used to optimize ECM process.A non-dominated solution set was obtained.展开更多
The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
文摘An ultra-precision servo control system for MWEDM (micro wire electrical discharge machining) based on piezoelectric ceramic motor drivers was developed. The servo discharge detection adopts an average voltage detection method, utilizes statistical methods to analyze the measured data, then controls discharge gap and makes the process more stable. The servo feed system based on DSP microprocessors applies a PID controller with incomplete derivation to reduce overshoot to improve machining accuracy, and also adopts adaptive dead-zone inverse compensation to eliminate dead-zone caused by piezoelectric ceramic motions in low servo feed speed. The simulation results show that the methods proposed in this paper can make the system recover its linearity and converge the dead-zone parameters. It is proved that the method proposed is efficient in solving this problem. Cooperating with a micro energy pulse generator, this equipment’s machining accuracy is smaller than ±0.2 micron, and surface roughness Ra is less than 0.1 micron. Punch die and cavity die (micro gear die, module 100 micron, thickness 3.5 millimeter) have been machined independently in two die steel work-pieces. These pieces can mate very well to work, which shows that the servo control system satisfies the need of MWEDM for high precision micro fabrication.
文摘Because of the relativity among the parameters, partial least square regression(PLSR)was applied to build the model and get the regression equation. The improved algorithm simplified the calculating process greatly because of the reduction of calculation. The orthogonal design was adopted in this experiment. Every sample had strong representation, which could reduce the experimental time and obtain the overall test data. Combined with the formation problem of gas metal arc weld with big current, the auxiliary analysis technique of PLSR was discussed and the regression equation of form factors (i.e. surface width, weld penetration and weld reinforcement) to process parameters(i.e. wire feed rate, wire extension, welding speed, gas flow, welding voltage and welding current)was given. The correlativity structure among variables was analyzed and there was certain correlation between independent variables matrix X and dependent variables matrix Y. The regression analysis shows that the welding speed mainly influences the weld formation while the variation of gas flow in certain range has little influence on formation of weld. The fitting plot of regression accuracy is given. The fitting quality of regression equation is basically satisfactory.
基金Sponsored by the National Natural Science Foundation of China (Grants No. 50801019,51071062)the State Key Lab of Advanced Metals Materials(Grant No.2009ZD-06)the National Basic Research Program of China (Grant No. 2011CB605504)
文摘The present work numerically investigates two-dimensional （2-D） solidification transport phenomena （EM-STP） during continuous casting （CC） process in the absence and the presence of static magnetic fields （SMFs）, based on a unified numerical model. For the purpose of controlling vortexes, the electromagnetic brake （EMBR） effects of various SMFs under the given depth of submerged entry nozzle （SEN） and the same casting velocity V0 are investigated. ANSYS software is used to analyze the SMFs that applied to the EMCC process, and then a data-conversion program based on the principle of linear interpolation proposed previously is used to deal with the issue of data-format-matching between FEM and FVM. The simulation results indicate that, an appropriate SMF can effectively suppress the bulk liquid flow in CC-process of steel plate, and with in- crease of the intensity of applied magnetic fields, the vortexes become weaker and the oscillating amplitude of impinging jet decreases. Based on the knowledge gained from the EMCC-STP analysis and by comparing the re- sults with the applied magnetic fields with those without magnetic fields, it is found that a SMF with 丨 Bmax 丨 = 5.5 × 10 -3 T can meet the need of braking, and consequently improve the quality of casting by reducing the penetration of non-metallic inclusions, as well as avoiding breakout, macro-segregation and crack ultimately.
基金Project supported by the National Natural Science Foundation of China (Nos. 50575128 and 50775128)the Outstanding Young Scientist Foundation of Shandong Province (No. 2005BS05004), China
文摘Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and time consuming. In this paper, artificial neural network (ANN) and genetic algorithm (GA) are used together to establish the parameter optimization model. An ANN model which adapts Levenberg-Marquardt algorithm has been set up to represent the relationship between material removal rate (MRR) and input parameters, and GA is used to optimize parameters, so that optimization results are obtained. The model is shown to be effective, and MRR is improved using optimized machining parameters.
文摘Electrochemical machining（ECM） is one of the important non-traditional machining processes,which is used for machining of difficult-to-machine materials and intricate profiles.Being a complex process,it is very difficult to determine optimal parameters for improving cutting performance.Metal removal rate and surface roughness are the most important output parameters,which decide the cutting performance.There is no single optimal combination of cutting parameters,as their influences on the metal removal rate and the surface roughness are quite opposite.A multiple regression model was used to represent relationship between input and output variables and a multi-objective optimization method based on a non-dominated sorting genetic algorithm-Ⅱ（NSGA-Ⅱ） was used to optimize ECM process.A non-dominated solution set was obtained.
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
