In the anticorrosive coating line of a welded tube plant, the current status and existing problems of the medium-frequency induction heating equipment were discussed.Partial renovations of the power control cabinet ha...In the anticorrosive coating line of a welded tube plant, the current status and existing problems of the medium-frequency induction heating equipment were discussed.Partial renovations of the power control cabinet have been conducted.Parameters such as the DC current, DC voltage, intermediate frequency power, heating temperature, and the positioning signal at the pipe end were collected.A data acquisition and processing system, which can process data according to user needs and provide convenient data processing functions, has been developed using LabVIEW software.This system has been successfully applied in the coating line for the automatic control of high-power induction heating equipment, production management, and digital steel tube and/or digital delivery.展开更多
The 45, 55, 65 and 100 kDa ATP-binding proteinases (ATP-BPases) of the heat-shocked (44 ℃ for 30 min, recovery for 12h) rat C6 glioma cells were purified by DEAE-ionexchange and ATP-affinity chromatography. Their mol...The 45, 55, 65 and 100 kDa ATP-binding proteinases (ATP-BPases) of the heat-shocked (44 ℃ for 30 min, recovery for 12h) rat C6 glioma cells were purified by DEAE-ionexchange and ATP-affinity chromatography. Their molecular masses, isoelectric points (pI), pH-optima and other properties were analyzed by native proteinase gels.It was shown that the 65 kDa ATP-BPase is specifically induced by heat shock and not detectable in control cells.Its N-terminal 1-9 amino acid sequence was determined by Edman degradation, but no homologies to other proteins in the protein data bases were found. 30 and 31 kDa proteinases can be cleaved from the 45, 55 and 65 kDa proteinases to which they are linked. A possible relationship of the heat-induced 65 kDa ATP-BPase with the ATP-dependent proteinases (ATP-DPases) in prokaryotes and eukaryotes is discussed.展开更多
A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the com...A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the combined effect of the thermal buoyancy and the electro-magnetic forces(EMFs)due to the channel type induction heating.The results indicate that the thermal loss of molten steel in the tundish can be compensated effectively by the channel type induction heating.In addition,the molten steel would flow upward under the thermal buoyancy which can reduce the erosion of refractory.Moreover,the upward flow would increase the residence time of the molten steel in the tundish which provide more opportunities for the inclusion to reach the top surface of the tundish.展开更多
In order to overcome the pollution of the tratitional nozzle sand into the molten steel in tundish,a new method is proposed in this paper.In this method,the nozzle sand is substituted with iron-carbon alloy particles ...In order to overcome the pollution of the tratitional nozzle sand into the molten steel in tundish,a new method is proposed in this paper.In this method,the nozzle sand is substituted with iron-carbon alloy particles which have the same or similar compositions as the liquid steel.During casting processes,iron-carbon alloy forms solidification shell and the sintered layer in the upper nozzle to block the molten steel.When the slide gate is opened,the eletromagnetic induction heating is used to melt them so as to achieve 100%smoothly steel teeming.The electromagnetic induction heating effects were analyzed theoretically in the new slide gate system.Then the new method has been experimentally tested by using self-designed experimental device.The results show that the electromagnetic induction heating can complete the steel teeming within the required time.Furthermore,this steel-teeming technology can further improve the cleanliness of liquid steel.展开更多
A three-dimensional finite element model of electromagnetic field and temperature field was developed to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification pr...A three-dimensional finite element model of electromagnetic field and temperature field was developed to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification process of molten steel.The results show that the increases of exciting current frequency make the effects of induction heat on solidification increase remarkably.Contrarily,the effects of induction heat on solidification process are weakened sharply with the increase of casting speed.Especially,when the casting speed exceeds a certain value,the effects of induction heat on solidification process are nearly negligible.展开更多
The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the ...The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the heating temperature of induction heating meets the demands of steel plate bending, and the deformation of a steel plate heated by induction heating can achieve the same effect as flame heating. Meanwhile, the finite element model of moving induction heating of the plate is developed, and the comparison of the residual strain fields and transverse shrinkage between these two kinds of heating shows that great similarity has been achieved.展开更多
The key to acquire good metallurgical effects with induction heating tundish is to understand the flow field,temperature field and the movement of inclusions in the tundish with different induction heating power curve...The key to acquire good metallurgical effects with induction heating tundish is to understand the flow field,temperature field and the movement of inclusions in the tundish with different induction heating power curves.Based on the production of a factory,this work established a multi-field coupling mathematical model to find out the link between the heating power curve and the metallurgical effects of the tundish.The results indicated that the heating efficiency of an induction heating tundish not only was affected by the heating power,but also related to the flow and temperature field in the tundish.When the induction heater was used intermittently and the induction heater was turned on,the molten steel was controlled by electromagnetic force,and the flow field basically remained stable.However,when the induction heater was turned off,the velocity of molten steel got small,and the thermal buoyancy could greatly change the flow,forming short-circuit flow;besides,large number of inclusions suddenly escaped from the outlet of the tundish.When the molten steel was heated continuously,the flow field,temperature field and inclusions behavior remained basically unchanged.Considering both energy saving and maintaining good metallurgical effects,continuous heating(the power increasing stepwise over time)should be selected.展开更多
This paper deals with finite element study of the scanning induction heating of the magnetic steel sheets in transversal flux devices,taking into account the magnetic nonlinearity and the dependence on temperature of ...This paper deals with finite element study of the scanning induction heating of the magnetic steel sheets in transversal flux devices,taking into account the magnetic nonlinearity and the dependence on temperature of steel properties.The decrease of the non-uniformity of the transversal profile of sheet heating as effect of the magnetic or electromagnetic screening of the sheet lateral sides was proved.展开更多
An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of...An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.展开更多
Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature dis...Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature distribution in the induction brazing model. The in?uences of induction brazing parameters on the residual stresses of polycrystalline CBN abrasive grits have been analyzed, including the embedding depth, grit side length, etc. Results obtained show that the tensile stress with a 40% embedding depth is 292 MPa, which is the minimum on the bonding interface compared with other embedding depths. Meanwhile, the maximum tensile stress is 575 MPa, with an increase of 59% compared with that of a grit side length of 50 mm. Finally, the simulation results of the brazing residual stress of polycrystalline CBN abrasive grits have been con?rmed valid based on the residual stress measurement of the brazed monocrystalline CBN grit.展开更多
Continuous steel strip casting lines in rolling miles are under active development.Due to high thermal losses the thin strip is cooling down very fast and therefore a sufficient heating system is necessary before fina...Continuous steel strip casting lines in rolling miles are under active development.Due to high thermal losses the thin strip is cooling down very fast and therefore a sufficient heating system is necessary before final rolling.Only induction heaters can realize the necessary fast heating of the strip and a good energy efEciency of heating.Because of induction heating lines for rolling mills are of extremely high power,all even small improvements in their design and operating modes have significant technical and economical effects.However,the heating lines need an optimal design of the complex induction systems and only numerical simulation is a way to solve the problem.Both two- and threedimensional numerical simulation approaches developed and applied for investigation and design of longitudinal induction heaters are described in the paper.The numerical models have been successfully used for development of modified coils allowing high efficient heating of thinner strip using the same operating frequency.Additionally electrical impedance of the modified coils has been provided on the level necessary for using the existing power supplies and matching equipment.Beside high electrical efficiency,the modified coils improve the temperature distribution over the strip width by increased heating of the strip edges.The optimized and modifies induction coils have been successfully tested in industrial line.展开更多
A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and ene...A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation equation.The spatial heat radiation between the slab surface and the refractory wall in an induction furnace was considered.The electromagnetic induction and temperature distribution features inside the slab with time evolution were described.The effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically examined.Numerical results show that the spatial distribution of induction heat generation inside the slab is non-uniform.The high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating process.The radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface temperature.It is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.展开更多
This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive ...This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.展开更多
Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the comp...Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the composites were examined by XRD,SEM and EDS.The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized.Around the titanium fibers,the reaction zones and diffusion zones can be obviously found.Due to the stirring of the electromagnetic function,the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles,and ensures the continuous reaction between liquid aluminum and titanium fibers,as well as the diffusion of Al3Ti particles.At the same time,there were secondary splits of Al3Ti particles located in diffusion zones.Two-body abrasion test shows that with the increase of induction heating power,the wear rates of the composites reduced and the number of grooves decreased.展开更多
The electromagnetic,flow,heat transfer and inclusions motion model of the channel-type induction heating(IH)tundish was established,and the effect of the channel diameter on the metallurgical behavior of the tundish w...The electromagnetic,flow,heat transfer and inclusions motion model of the channel-type induction heating(IH)tundish was established,and the effect of the channel diameter on the metallurgical behavior of the tundish was studied.The results show that the magnetic field in the channel of the IH tundish tends to concentrate on the surface layer and the side near the coil.As the channel diameter is increased from 100 to 180 mm,the maximum value of magnetic flux density in the channel decreases by 0.125 T,and the maximum value of electromagnetic force decreases by 11.83×10^(5) N m^(-3);however,the off-center distance of magnetic field increases by 9.4 mm,and the Joule heat in the channel decreases by 1004 kW,which leads to the reduction in temperature rising rate of the tundish from 1.41 to 0.59 K min^(-1).When the channel diameter is 100,140 and 180 mm,the maximum velocity at the channel exit before heating is 0.59,0.29 and 0.18 m s^(-1),and after heating for 1800 s,it is 1.52,1.12 and 0.92 m s^(-1),respectively.In addition,the total inclusions escape ratio after heating for 1800 s with a channel diameter of 140 mm can be reduced by 12.39% compared to that before heating,and the maximum difference of escape ratios for each strand is only 4.51% and 5.32% before heating and after heating for 1800 s,respectively.Compared with the channel diameters of 100 and 180 mm,the channel diameter of 140 mm is more favorable to improve the metallurgical effect of the IH tundish.展开更多
Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless indu...Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating.By adjusting the reaction conditions,the catalyst is able to perform CO_(2)methanation reaction under autothermal process operated inside a non-adiabatic reactor,without any external energy supply.Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out.Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor,where complete insulation is required to prevent heat disequilibrium,in order to reduce as much as possible,the heat exchange with the external medium.The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation.It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.展开更多
In the production of hot extrusion pipes, the billet will be heated in an induction furnace, before piercing or extrusion,to a certain temperature. The induction heating temperature field profile in the billet will ex...In the production of hot extrusion pipes, the billet will be heated in an induction furnace, before piercing or extrusion,to a certain temperature. The induction heating temperature field profile in the billet will exert an influence on the deformation processes. The study has developed an data conversion program to convert the temperature data from induction heating by ANSYS to deformation simulation software DEFORM; therefore, not only the relatively accurate temperature field can be made available, compared with the usually assumed uniform temperature field, but also the connection between induction heating and deformation can be established, which is essential to evaluate the processing parameters. Numerical simulation of the piercing processes of different temperature fields by induction heating was carded out, and the results have shown that the different initial temperature fields in the billet can lead to different deformation curves, which indicates that the conversion program is necessary to study the production process of hot extrusion pipes.展开更多
A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated ...A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.展开更多
Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Cont...Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Control of the induction heating temperature to an appropriate value is a key consideration in induction heating technology. To obtain acculturated temperatures, investigations were focused on the parameters of an induction heating system, including those of induction heating equipment and heating processes. In these investigations, computer simulation was used to model the induction heating process, followed by physical experimentation to verify and improve the simulation model; finally, optimized induction heating parameters were suggested. The use of computer simulations dramatically decreased physical experimental times, and the computed heating parameters were used to guide the physical experimentation and design of the product line ; this increased the efficiency of subsequent investigations. This study focuses on the development of induction heating technology in Baosteel, which includes the overall induction heating technology used in manufacturing backup rollers and in the thermomechanical control process.展开更多
This paper is devoted to the study of frequency effects on hardness profile of AISI 4340 spline shaft heat-treated by induction through an extensive 3D finite element method simulation and structured experimental inve...This paper is devoted to the study of frequency effects on hardness profile of AISI 4340 spline shaft heat-treated by induction through an extensive 3D finite element method simulation and structured experimental investigation. Based on coupled electromagnetic and thermal fields analysis, the 3D model is used to estimate the temperature distribution and the hardness profile. The proposed study examines the hardening process parameters, such as frequency, induced current density and heating time, known to have an influence on hardened surface and builds the simulation model step by step. The established model can provide not only an accurate prediction of temperature distribution and hardness profile but also a comprehensive analysis of machine parameters effects, especially the frequency. The numerical results achieved by this model are good and present a great agreement to the experimental data.展开更多
文摘In the anticorrosive coating line of a welded tube plant, the current status and existing problems of the medium-frequency induction heating equipment were discussed.Partial renovations of the power control cabinet have been conducted.Parameters such as the DC current, DC voltage, intermediate frequency power, heating temperature, and the positioning signal at the pipe end were collected.A data acquisition and processing system, which can process data according to user needs and provide convenient data processing functions, has been developed using LabVIEW software.This system has been successfully applied in the coating line for the automatic control of high-power induction heating equipment, production management, and digital steel tube and/or digital delivery.
文摘The 45, 55, 65 and 100 kDa ATP-binding proteinases (ATP-BPases) of the heat-shocked (44 ℃ for 30 min, recovery for 12h) rat C6 glioma cells were purified by DEAE-ionexchange and ATP-affinity chromatography. Their molecular masses, isoelectric points (pI), pH-optima and other properties were analyzed by native proteinase gels.It was shown that the 65 kDa ATP-BPase is specifically induced by heat shock and not detectable in control cells.Its N-terminal 1-9 amino acid sequence was determined by Edman degradation, but no homologies to other proteins in the protein data bases were found. 30 and 31 kDa proteinases can be cleaved from the 45, 55 and 65 kDa proteinases to which they are linked. A possible relationship of the heat-induced 65 kDa ATP-BPase with the ATP-dependent proteinases (ATP-DPases) in prokaryotes and eukaryotes is discussed.
基金Item Sponsored by National Natural Science Foundation of China[No.50934008]National Natural Science Foundation of China[NO.50904014]
文摘A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the combined effect of the thermal buoyancy and the electro-magnetic forces(EMFs)due to the channel type induction heating.The results indicate that the thermal loss of molten steel in the tundish can be compensated effectively by the channel type induction heating.In addition,the molten steel would flow upward under the thermal buoyancy which can reduce the erosion of refractory.Moreover,the upward flow would increase the residence time of the molten steel in the tundish which provide more opportunities for the inclusion to reach the top surface of the tundish.
基金Item Sponsored by the Science and Technology Program of Liaoning Province(Grant No.2011221009)the 111 project(Grant No.B07015)
文摘In order to overcome the pollution of the tratitional nozzle sand into the molten steel in tundish,a new method is proposed in this paper.In this method,the nozzle sand is substituted with iron-carbon alloy particles which have the same or similar compositions as the liquid steel.During casting processes,iron-carbon alloy forms solidification shell and the sintered layer in the upper nozzle to block the molten steel.When the slide gate is opened,the eletromagnetic induction heating is used to melt them so as to achieve 100%smoothly steel teeming.The electromagnetic induction heating effects were analyzed theoretically in the new slide gate system.Then the new method has been experimentally tested by using self-designed experimental device.The results show that the electromagnetic induction heating can complete the steel teeming within the required time.Furthermore,this steel-teeming technology can further improve the cleanliness of liquid steel.
基金Item Sponsored by College Natural Science Research Project of Jiangsu Province of China(05KJD450043)
文摘A three-dimensional finite element model of electromagnetic field and temperature field was developed to investigate the effects of induction heat of high frequency electromagnetic field on the early solidification process of molten steel.The results show that the increases of exciting current frequency make the effects of induction heat on solidification increase remarkably.Contrarily,the effects of induction heat on solidification process are weakened sharply with the increase of casting speed.Especially,when the casting speed exceeds a certain value,the effects of induction heat on solidification process are nearly negligible.
基金Supported by the National Natural Science Foundation of China (50805016)
文摘The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the heating temperature of induction heating meets the demands of steel plate bending, and the deformation of a steel plate heated by induction heating can achieve the same effect as flame heating. Meanwhile, the finite element model of moving induction heating of the plate is developed, and the comparison of the residual strain fields and transverse shrinkage between these two kinds of heating shows that great similarity has been achieved.
基金supported by National Natural Science Foundation of China(51474065 and 51574083)the 111 Project(2.0)of China(No.BP0719037).
文摘The key to acquire good metallurgical effects with induction heating tundish is to understand the flow field,temperature field and the movement of inclusions in the tundish with different induction heating power curves.Based on the production of a factory,this work established a multi-field coupling mathematical model to find out the link between the heating power curve and the metallurgical effects of the tundish.The results indicated that the heating efficiency of an induction heating tundish not only was affected by the heating power,but also related to the flow and temperature field in the tundish.When the induction heater was used intermittently and the induction heater was turned on,the molten steel was controlled by electromagnetic force,and the flow field basically remained stable.However,when the induction heater was turned off,the velocity of molten steel got small,and the thermal buoyancy could greatly change the flow,forming short-circuit flow;besides,large number of inclusions suddenly escaped from the outlet of the tundish.When the molten steel was heated continuously,the flow field,temperature field and inclusions behavior remained basically unchanged.Considering both energy saving and maintaining good metallurgical effects,continuous heating(the power increasing stepwise over time)should be selected.
文摘This paper deals with finite element study of the scanning induction heating of the magnetic steel sheets in transversal flux devices,taking into account the magnetic nonlinearity and the dependence on temperature of steel properties.The decrease of the non-uniformity of the transversal profile of sheet heating as effect of the magnetic or electromagnetic screening of the sheet lateral sides was proved.
基金Supported by the National Science and Technology Major Project of China(2012ZX04003081)
文摘An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.
基金supported by the National Natural Science Foundation of China(No.51775275)the Fundamental Research Funds for the Central Universities(No.NE2014103 and No.NZ2016107)
文摘Residual stresses produced in polycrystalline CBN abrasive grits during a high-frequency induction brazing process are calculated by using ?nite element analysis, with a consideration of the nonuniform temperature distribution in the induction brazing model. The in?uences of induction brazing parameters on the residual stresses of polycrystalline CBN abrasive grits have been analyzed, including the embedding depth, grit side length, etc. Results obtained show that the tensile stress with a 40% embedding depth is 292 MPa, which is the minimum on the bonding interface compared with other embedding depths. Meanwhile, the maximum tensile stress is 575 MPa, with an increase of 59% compared with that of a grit side length of 50 mm. Finally, the simulation results of the brazing residual stress of polycrystalline CBN abrasive grits have been con?rmed valid based on the residual stress measurement of the brazed monocrystalline CBN grit.
文摘Continuous steel strip casting lines in rolling miles are under active development.Due to high thermal losses the thin strip is cooling down very fast and therefore a sufficient heating system is necessary before final rolling.Only induction heaters can realize the necessary fast heating of the strip and a good energy efEciency of heating.Because of induction heating lines for rolling mills are of extremely high power,all even small improvements in their design and operating modes have significant technical and economical effects.However,the heating lines need an optimal design of the complex induction systems and only numerical simulation is a way to solve the problem.Both two- and threedimensional numerical simulation approaches developed and applied for investigation and design of longitudinal induction heaters are described in the paper.The numerical models have been successfully used for development of modified coils allowing high efficient heating of thinner strip using the same operating frequency.Additionally electrical impedance of the modified coils has been provided on the level necessary for using the existing power supplies and matching equipment.Beside high electrical efficiency,the modified coils improve the temperature distribution over the strip width by increased heating of the strip edges.The optimized and modifies induction coils have been successfully tested in industrial line.
文摘A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation equation.The spatial heat radiation between the slab surface and the refractory wall in an induction furnace was considered.The electromagnetic induction and temperature distribution features inside the slab with time evolution were described.The effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically examined.Numerical results show that the spatial distribution of induction heat generation inside the slab is non-uniform.The high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating process.The radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface temperature.It is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.
文摘This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.
基金Project(2015DFR50990-01)supported by International Cooperation Project of Ministry of Science and Technology of ChinaProjects(18JS060,18JS075)supported by the Shaanxi Key Laboratory of Nano-materials and Technology,China。
文摘Under various electromagnetic induction heating powers,different Al3Ti/Al composites were fabricated by in-situ synthesis method from aluminum and titanium fibers.Microstructures and particles distribution of the composites were examined by XRD,SEM and EDS.The results show that no other intermetallic compounds beside Al3Ti can be in-situ synthesized.Around the titanium fibers,the reaction zones and diffusion zones can be obviously found.Due to the stirring of the electromagnetic function,the formation of the micro-cracks inside the reaction zone was conducive to the peeling off of the Al3Ti particles,and ensures the continuous reaction between liquid aluminum and titanium fibers,as well as the diffusion of Al3Ti particles.At the same time,there were secondary splits of Al3Ti particles located in diffusion zones.Two-body abrasion test shows that with the increase of induction heating power,the wear rates of the composites reduced and the number of grooves decreased.
基金funded by the National Natural Science Foundation of China(NSFC)(Grant Nos.51874033 and U1860111).
文摘The electromagnetic,flow,heat transfer and inclusions motion model of the channel-type induction heating(IH)tundish was established,and the effect of the channel diameter on the metallurgical behavior of the tundish was studied.The results show that the magnetic field in the channel of the IH tundish tends to concentrate on the surface layer and the side near the coil.As the channel diameter is increased from 100 to 180 mm,the maximum value of magnetic flux density in the channel decreases by 0.125 T,and the maximum value of electromagnetic force decreases by 11.83×10^(5) N m^(-3);however,the off-center distance of magnetic field increases by 9.4 mm,and the Joule heat in the channel decreases by 1004 kW,which leads to the reduction in temperature rising rate of the tundish from 1.41 to 0.59 K min^(-1).When the channel diameter is 100,140 and 180 mm,the maximum velocity at the channel exit before heating is 0.59,0.29 and 0.18 m s^(-1),and after heating for 1800 s,it is 1.52,1.12 and 0.92 m s^(-1),respectively.In addition,the total inclusions escape ratio after heating for 1800 s with a channel diameter of 140 mm can be reduced by 12.39% compared to that before heating,and the maximum difference of escape ratios for each strand is only 4.51% and 5.32% before heating and after heating for 1800 s,respectively.Compared with the channel diameters of 100 and 180 mm,the channel diameter of 140 mm is more favorable to improve the metallurgical effect of the IH tundish.
基金ORANO Chimie-Enrichissement Co.for the financial support of this project。
文摘Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating.By adjusting the reaction conditions,the catalyst is able to perform CO_(2)methanation reaction under autothermal process operated inside a non-adiabatic reactor,without any external energy supply.Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out.Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor,where complete insulation is required to prevent heat disequilibrium,in order to reduce as much as possible,the heat exchange with the external medium.The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation.It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.
文摘In the production of hot extrusion pipes, the billet will be heated in an induction furnace, before piercing or extrusion,to a certain temperature. The induction heating temperature field profile in the billet will exert an influence on the deformation processes. The study has developed an data conversion program to convert the temperature data from induction heating by ANSYS to deformation simulation software DEFORM; therefore, not only the relatively accurate temperature field can be made available, compared with the usually assumed uniform temperature field, but also the connection between induction heating and deformation can be established, which is essential to evaluate the processing parameters. Numerical simulation of the piercing processes of different temperature fields by induction heating was carded out, and the results have shown that the different initial temperature fields in the billet can lead to different deformation curves, which indicates that the conversion program is necessary to study the production process of hot extrusion pipes.
基金financially supported by National Science Foundation of China ( NO. 51274137 and NO. 11372174)
文摘A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.
文摘Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Control of the induction heating temperature to an appropriate value is a key consideration in induction heating technology. To obtain acculturated temperatures, investigations were focused on the parameters of an induction heating system, including those of induction heating equipment and heating processes. In these investigations, computer simulation was used to model the induction heating process, followed by physical experimentation to verify and improve the simulation model; finally, optimized induction heating parameters were suggested. The use of computer simulations dramatically decreased physical experimental times, and the computed heating parameters were used to guide the physical experimentation and design of the product line ; this increased the efficiency of subsequent investigations. This study focuses on the development of induction heating technology in Baosteel, which includes the overall induction heating technology used in manufacturing backup rollers and in the thermomechanical control process.
文摘This paper is devoted to the study of frequency effects on hardness profile of AISI 4340 spline shaft heat-treated by induction through an extensive 3D finite element method simulation and structured experimental investigation. Based on coupled electromagnetic and thermal fields analysis, the 3D model is used to estimate the temperature distribution and the hardness profile. The proposed study examines the hardening process parameters, such as frequency, induced current density and heating time, known to have an influence on hardened surface and builds the simulation model step by step. The established model can provide not only an accurate prediction of temperature distribution and hardness profile but also a comprehensive analysis of machine parameters effects, especially the frequency. The numerical results achieved by this model are good and present a great agreement to the experimental data.
