Numerical analysis on Joule heating of double-loop channel induction furnaces

In order to investigate Joule heating power,a three-dimensional finite element model(FEM) was developed to predict Joule heating power in the channels of double-loop inductor. The simulated results were compared with experimental data from low load trials for a 400 kW inductor. The results,such as power factor and Joule heating power,show reasonable correlation with experimental data,and Joule heating rate reaches the maximum at the corners and the minimum at the centre of the cross-section area. With increasing relative permeability of iron core,length of coils,current frequency and resistivity of metal melt,the power factor and Joule heating power change. It is concluded that current frequency,the resistivity and length of the coil play a critical role in determining the power factor and Joule heating power,whereas relative permeability of the magnetic core shows no significant influence on them.

Investigations of high-frequency induction hardening process for piston rod of shock absorber

The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

Corrosion Mechanism of Alumina-magnesia Dry Materials for Smelting Manganese/chromium Steel in Coreless Medium Frequency Induction Furnaces

Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composition, and microstructure of the post-use dry materials for the working liners melting different kinds of steel were evaluated. Furthermore, the corrosion mechanism of the steel on the furnace lining materials was comprehensively analyzed. The findings reveal a significant ability of the Mn element in the molten steel to diffuse and penetrate into the refractories. Mn oxidizes to form MnO at the steel-refractory interface, and then forms a liquid phase with Al_(2)O_(3). The Cr element is dissolved into corundum and spinel of the refractories, resulting in lattice defects and structural damage of the materials. TiO2reacts with Al_(2)O_(3) to form Al_(2)TiO_(5), which plays a crucial role in preventing crack formation and propagation. Part of Ti4+dissolves into magnesia-alumina(MA), densifying the materials. TiO2also slows down the reaction between the Cr element and refractory components, further improving the corrosion resistance of the materials.

Improvement of the Structure and the Electromagnetic Characteristics of an Induction Ladle Furnace

Based on a numerical analysis of the alternating electromagnetic field in the process of Steel refining with an induction ladle furnace (ILF), the optimization of the structure of ILF and the electromagnetic field for melting is realized in the present work. The optimization of the ILF by outward extension of inner yokes can decrease the magnitic flux leakage obviously, reduce the eddy current energy loss dramatically and then, decrease the total power consumption.

Influences of Binders on Properties of Highalumina Repairing Mix for Medium-frequency Induction Furnace

Three kinds of high-alumina repairing mixes for medium-frequency induction furnace were prepared by ramming method with sodium silicate, phosphoric acid and aluminium dihydrogen phosphate as binder, respectively. Physical properties of the specimens heat treated at different temperatures were tested and compared. The results show that the specimen bonded by sodium silicate behaves much higher strength after fired at 1 600 ℃ compared with the specimen, bonded by phosphoric acid or aluminium dihydrogen phosphate. Due to more liquid phase formation the properties of specimen bonded by sodium silicate are poor with a low strength and a large volume shrinkage at high temperatures. Meanwhile. the speeimen bonded by phosphoric acid and aluminium dihydrogen phosphate, respectively, show relatively high strengths and slight volume expansions at high temperatures because of in-situ mullite formation.

Melting Time Prediction Model for Induction Furnace Melting Using Specific Thermal Consumption from Material Charge Approach

A system-level evaluation was used to analyze the induction furnace operation and process system in this study. This paper presents an investigation into the relationship between the instantaneous chemical composition of a molten bath and its energy consumption in steelmaking. This was evaluated using numerical modelling to solve for the estimated melting time prediction for the induction furnace operation. This work provides an insight into the lowering of energy consumption and estimated production time in steelmaking using material charge balancing approach. Enthalpy computation was implemented to develop an energy consumption model for the molten metal using a specific charge composition approach. Computational simulation program engine (CastMELT) was also developed in Java programming language with a MySQL database server for seamless specific charge composition analysis and testing. The model performance was established using real-time production data from a cast iron-based foundry with a 1 and 2-ton induction furnace capacity and a medium carbon-based foundry with a 10- and 15-ton induction furnace capacity. Using parameter fitting techniques on the measured operational data of the induction furnaces at different periods of melting, the results from the model predictions and real-time melting showed good correlation between 81% - 95%. A further analysis that compared the relationship between the mass composition of a current molten bath and melting, time showed that energy consumption can be reduced with effective material balancing and controlled charge. Melting time was obtained as a function of the elemental charge composition of the molten bath in relation to the overall scrap material charge. This validates the approach taken by this research using material charge and thermodynamic of melting to optimize and better control melting operation in foundry and reduce traditional waste during iron and steel making.

Features and control methods of the galvanneal furnace

The recent rapid developments in the automobile industry have demanded the extensive use of gaivannealed （GA） steel sheets.In particular,the development of lightweight automobiles is putting increasingly higher requirements on the strength of GA steel sheets.The galvanneal furnace,which is used for processing galvannealed steel sheets,is typically composed of the induction heating section,holding section and fog cooling section.This paper described the structural characteristics of each component of the galvanneal furnace,and analyzed temperature control methods of the galvanneal furnace that are important for the successful production of high-strength GA steel sheets for automotive applications.

Local High-Frequency Heating in Electronics Technology

Modeling and investigation of HF electromagnetic heating in induction devices with unclosed magnetic circuit has allowed to optimize heating speed in local zones of formation of soldering connections and to improve their quality due to joint action of superficial effects and electromagnetic forces.For all magnetic materials is nonlinear decrease in heating power depending on frequency of HF.Installed the optimal parameters of HF heating for soldering electronics modules by inductor with open-ended magnetic conductor.

Numerical Simulation of Electromagnetic Field and Temperature Field in Medium-Frequency Induction Furnace Melting Process

A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.

Residual stresses of polycrystalline CBN abrasive grits brazed with a high-frequency induction heating technique

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.

Physics Informed Neural Network-based High-frequency Modeling of Induction Motors

The high-frequency(HF)modeling of induction motors plays a key role in predicting the motor terminal overvoltage and conducted emissions in a motor drive system.In this study,a physics informed neural network-based HF modeling method,which has the merits of high accuracy,good versatility,and simple parameterization,is proposed.The proposed model of the induction motor consists of a three-phase equivalent circuit with eighteen circuit elements per phase to ensure model accuracy.The per phase circuit structure is symmetric concerning its phase-start and phase-end points.This symmetry enables the proposed model to be applicable for both star-and delta-connected induction motors without having to recalculate the circuit element values when changing the motor connection from star to delta and vice versa.Motor physics knowledge,namely per-phase impedances,are used in the artificial neural network to obtain the values of the circuit elements.The parameterization can be easily implemented within a few minutes using a common personal computer(PC).Case studies verify the effectiveness of the proposed HF modeling method.

Numerical Analysis and Experimental Verification of the Behaviour of Solid Inclusions in Induction Crucible Furnaces

The paper refers to the dynamics of solid inclusion in the turbulent flow of liquid metal in induction furnaces. The numerical analysis is carried out adopting LES-based Euler-Lagrange approach in the limit of dilute conditions.The admixing of carbon particles in induction crucible furnace from the open surface of a melt is simulated.The behaviour of the particles in the bulk of the flow is illustrated as well as compared with the industrial observation of the open surface of the alloy.The paper also contains the description of the novel experimental technique,which is proposed for the verification of the numerical model.The experiment deals with ferromagnetic particles in the flow of Wood's metal in the small induction crucible furnace.This experiment confirms the satisfactory agreement with the numerical results.

Boron Removal From Metallurgical Grade Silicon by Molten Slag Refining in Induction Furnace

The impurities Al,Ca,Ti,B,P etc in metallurgical grade silicon(MG-Si)can be effectively removed by refining using molten slag based CaO-SiO_2,and it is especially effective for boron removal.The experiments of boron removal were studied using CaO-SiO_2 binary slag in induction furnace.The results showed that the distribution coefficient of boron(L_B)between slag and silicon increased with more proportion of CaO/SiO_2(mass%).It was advantaged to boron removal for higher basicity of slag,so the boron in MG-Si was reduced from 18ppmw to 1.4ppmw with the addition of Li_2O and K_2O to CaO-SiO_2 slag.The proportion of SiO_2 in slag affected the oxidizing capacity of slag,which reduced the efficiency of boron removal.

High-Frequency Induction Heating of Needle-Shaped Mg-Ferrite for Ablation Therapy of Human Cancer

For application as a novel ablation therapy of human cancer,the heating property of a needle-shaped Mg-ferrite prepared by a sintering technique was studied in a high-frequency induction field at 370 kHz.When inserted into cylindrical clay,the increase in temperature(Δ7)was 31.2℃ for the specimen with a 1.5 mm diameter,while the 1.0mm diameter specimen exhibited a ΔT value of 15.7℃ after the induction time of 1200s.The ΔT exhibited a high value of 57.9℃ during the simultaneous insertion of 3 1.5mm diameter specimens.In the computer simulation images, the relatively lower magnetic flux density and concurrent neghgibly low current density were observed from the surface to the internal regions,being different from the behavior of a ferromagnetic Ni-rod with the same size.

Compressive Strength and Interface Microstructure of PCBN Grains Brazed with High-Frequency Induction Heating Method

In order to prepare monolayer brazed superabrasive wheels, the polycrystalline cubic boron nitride（PCBN）grains were brazed to AISI 1045 steel matrix with Ag–Cu–Ti filler alloy using the high-frequency induction heating technique. The compressive strengths of brazed grains were measured. Morphology, chemical composition and phase component of the brazing resultant around PCBN grain were also characterized. The results show that the maximum compressive strength of brazed grains is obtained in the case of brazing temperature of 965 °C, which does not decrease the original grain strength. Strong joining between Ag–Cu–Ti alloy and PCBN grains is dependent on the brazing resultants,such as TiB_2, TiN and AlTi_3, the formation mechanism of which is also discussed. Under the given experimental conditions, the optimum heating parameters were determined to be current magnitude of 24 A and scanning speed of0.5 mm/s. Finally, the brazing-induced residual tensile stress, which has a great influence on the grain fracture behavior in grinding, was determined through finite element analysis.

Inconel 601镍基高温合金真空感应熔炼脱氧工艺研究

研究了采用国产大型真空感应炉熔炼Inconel 601镍基高温合金的脱氧工艺。从热力学上计算了合金熔液中碳氧反应平衡值。通过调整熔炼工艺参数,确定了影响氧含量及合金轧制质量的工艺参数最佳范围。结果表明:熔化时间为365~370 min、真空度为1.0~1.2 Pa及C初始加入量为0.050%时,合金氧含量可降至10×10^(-6)以内,脱氧率可达90%以上。采用6 t国产大型真空感应炉可生产出高纯净度的镍基高温合金产品。

基于矿热炉多物理场耦合数值研究还原熔炼过程

建立了瞬态三维数学模型,分析了矿热炉冶炼过程中多物理场分布。该模型利用用户自定义函数(UDF)实现了电热转换、电磁感应和还原反应,对炉内电场、磁场、温度场和质量分数场进行模拟。结果表明:随着电极插入深度的增加,熔池最大温度逐渐升高;焦耳热随时间也不断增加,同电流一样在电弧内侧边缘出现明显的趋肤效应和邻近效应;氧化镍在电弧下方反应强烈,并向两侧逐渐减弱,随着电极插入深度的增加,电弧上方的反应反而变慢,综合考虑2.1 m为最佳电极插入深度。

纺织品及附件铅释放量的测定

文章建立以人工睡液为萃取介质,测定纺织品及纺织品附件中铅释放量的试验方法,优化样品前处理条件和测试仪器参数。试验结果表明:采用电感耦合等离子体发射光谱法测定的定量限为0.02μg/(cm^(2)·h),在低、中、高3个加标浓度下的回收率在93.26%~107.65%,相对标准偏差为1.03%~5.99%(n=7);采用石墨炉原子吸收光谱法测定的定量限为0.01μg/(cm^(2)·h),在低、中、高3个加标浓度下的回收率在82.65%~110.32%,相对标准偏差为1.08%~4.61%(n=7)。该方法前处理步骤简单,检测流程短,结果准确度高,适用于可放入婴幼儿和儿童口中的纺织品及其附件的检测。

基于TRNSYS的太阳能-电能互补采暖系统研究

针对我国北方农村地区冬季采暖污染严重、碳排放量大等问题,文章以沈阳市某地区典型农村单体式住宅为研究对象,综合考虑太阳能、电能,提出2套清洁供暖方案。首先对太阳能集热器的集热倾角和面积的选择进行优化,然后选取沈阳市供暖季温度较低的2天,根据天气情况分别作为晴天与阴天典型日,最后利用TRNSYS软件对供暖方案在典型日天气条件下模拟运行。结果表明在典型日天气条件下本研究提出的2种供暖方案均满足环保、室内温度适宜等采暖需求,且太阳能集热器+变频电磁采暖炉供暖方案更为节能。

感应熔炼炉炉衬损耗监测系统设计

为进一步消除炼钢和铸造行业中机械生产和加工设备的安全隐患,基于感应接触式炉衬损耗监测技术,设计一种炉衬损耗监测系统。该系统在感应熔炼炉运行过程中实时采集感应圈回路与中间金属层回路的电流值,根据两回路电流值判断感应熔炼炉是否出现炉衬损耗,评估损耗状况,并在回路电流值达到设定阈值后及时发出对应的信号提醒工作人员。经实验验证表明,系统能够提升炉衬损耗监测的可靠性,同时提高了熔炼炉生产的安全性以及工作人员对炉衬损耗状况判断的便利性。