Induction Heating Device Research Articles

Selective induction hyperthermia following transcatheter arterial embolization with a mixture of nano-sized magnetic particles (ferucarbotran) and embolic materials: feasibility study in rabbits

To evaluate the possibility of selective hyperthermia following transcatheter arterial embolization (TAE) with ferucarbotran using a newly developed inductive heating (IH) device. Twelve Japanese white rabbits were separated into four groups: those treated with TAE using a mixture of ferucarbotran and lipiodol (F-L group); those treated with ferucarbotran and gelatin sponge powder; those treated with saline and lipiodol; and a control group. These four groups received IH. Nine rabbits with renal VX2 carcinoma were separated into three groups: IH after TAE (IH-TAE tumor), TAE without IH (TAE tumor), and no treatment (control tumor). The temperature of the tumor was kept at 45 degrees C for 20 min. The therapeutic effect was pathologically evaluated by TUNEL staining. In the heating rates of the kidney, the F-L group showed significantly greater values than the group in which iron was not used. In the IH-TAE tumor group, tumors could be selectively heated. In TUNEL staining, the IH-TAE tumor and TAE tumor groups showed significantly greater values of apoptosis rate than in the control tumor group. IH following TAE with a mixture of ferucarbotran and lipiodol was capable of inducing selective hyperthermia with our device. However, further investigation is needed to confirm its safety and effectiveness in the treatment of malignant neoplasms in humans.

Investigating the effects of external fields polarization on the coupling of pure magnetic waves in the human body in very low frequencies

In this paper we studied the effects of external fields' polarization on the coupling of pure magnetic fields into human body. Finite Difference Time Domain (FDTD) method is used to calculate the current densities induced in a 1 cm resolution anatomically based model with proper tissue conductivities. Twenty different tissues have been considered in this investigation and scaled FDTD technique is used to convert the results of computer code run in 15 MHz to low frequencies which are encountered in the vicinity of industrial induction heating and melting devices. It has been found that external magnetic field's orientation due to human body has a pronounced impact on the level of induced currents in different body tissues. This may potentially help developing protecting strategies to mitigate the situations in which workers are exposed to high levels of external magnetic radiation.

Rapid Transformation Annealing: a Novel Method for Grain Refinement of Cold-Rolled Low-Carbon Steels

A novel heat treatment, rapid transformation annealing (RTA) is introduced, which uses the refining effect of the phase transformation during recrystallization annealing. The RTA is comprised of rapid heating including the full or partial phase transformation of cold-rolled, nonrecrystallized, or partly recrystallized α microstructure to γ microstructure combined with subsequent rapid cooling to ambient temperature. In this way, a substantial grain refinement compared to conventional industrial annealing of cold-rolled strip can be realized. Minimum homogeneous grain sizes of 2.3 μm are produced in microalloyed high-strength low-alloy (HSLA) steels. A plain low-carbon steel shows despite any microalloying grain sizes of about 2.5 μm. Grain refinement results in a substantial increase in strength and in a pronounced strain hardening in the ΘIV stage. Simultaneously, the uniform and total elongation slightly decrease, which is a physical consequence of Considere’s instability criterion. By a refinement from 4.2 to 2.3 μm, the yield and tensile strength of a HSLA grade can be increased by about 130 MPa to 535 and 650 MPa, while the total elongation is reduced by about four percentage points to 21 pct, i.e., a still moderate formability is provided. In general, the ductility-strength relationship remains similar to the conventional behavior. For all investigated steel grades, the Hall–Petch (HP) relationship is fulfilled. Furthermore, it is proved that RTA cycles can be realized in pilot scale as far as induction heating devices are applied.

Determination of the Effective Impedance of a Cylindrical Induction Heating Device Excited by Rotary Magnetic Fields

In this paper mathematical modeling of circuit parameters that feature the electric performance of a traveling-wave heating induction device is carried out. Rotary magnetic fields are the excitation source, and they come from axial windings having one pair of magnetic poles. The method employed for obtaining impedance parameters is based on main magnetic flux decomposition to partial fluxes along different regions that comprise the assembly. The modeled parameters are compared to those estimated from measurements of an experimental device at 60 Hz. Trials on both magnetic and non-magnetic load showed deviation between theoretical and measured parameters around 7%.

電磁誘導加熱装置を用いた接着工法に関する研究(材料施工)

A new type of induction heating device is now under way to develop. It is becoming a useful tool to fix interior or exterior finishing materials to structural frames and parts of other object firmly with glue. It is quite light and to prevent construction noises and machine throbs. The purposes of the experiment were to evaluate structure materials bonded together firmly with this device and to know possibility of applying new bonding method with the device to forming on earthquake-resistant walls. The experimental results showed as follows : (1) Compared to the strength of plywood itself, beyond which the destruction must be caused, the bonding strength produced by fixing plywood on plywood firmly with the induction heating device increased, exposing itself to the temperature and humidity in the bathroom for one year. (2) The time needed to separate bonded structure materials was 1.5 to 2.0 times as much as one needed to bond structure material together. (3) The time needed to bond structural steel to plywood with the induction heating device required 40 to 50 seconds, because structural steel has a large amount of absorption of heat.

Analysis of a new induction heating device by using permanent magnets

This paper presents results obtained in the designing of a heating device, which utilized eddy current induced by rotating permanent magnets. The finite-element method, by using overlap grid coordinate system, is used for the eddy-current analyses. In order to solve eddy-current problems that consist of several conductive objects, which are moving in magnetic field, we have to remesh the region under consideration according to those positions, in the step-by-step computation. To reduce the computation time, a composite mesh scheme is introduced into such eddy-current problems. The heat conduction analysis is also carried out after calculating the eddy-current distributions. The results show that the device is very useful to dry powders and grains.

The optimisation of induction heating system based on multiquadric function approximation

PurposeThe investigation of the efficiency of optimisation technique based on approximation of objective function by multiquadric (MQ) function, used for induction heating devices was the aim of the paper.Design/methodology/approachThe optimisation package based on Matlab language and using Flux2D commercial program for calculation of electromagnetic and thermal fields was built. It allows the use of different optimisation techniques for induction heating devices, e.g. based on MQ function approximation. In the paper two algorithms of approximated points generating have been tested.FindingsThe efficiency of MQ optimisation method strongly depends on the applied algorithm of approximated point generating. To ensure high efficiency of MQ optimisation method, the stochastic element of the algorithm of approximated point generating should have a significant role.Research limitations/implicationsThe efficiency of elaborated algorithms of MQ function approximated point generating should be proved in other applications.Practical implicationsThe efficient optimisation technique of induction heating devices has been proposed.Originality/valueThe two new algorithms for generation of MQ function approximated points have been proposed. The paper could be useful for designers of induction heating devices.

The Effects of the Heating Conditions on the Hydro-Formability of the Aluminum Alloys at High Temperatures

Modern automobiles are built with a steadily increasing variety of materials and semifinished products. The traditional composition of steel sheet and cast iron is being replaced with other materials such as aluminum and magnesium. But low formability of these materials has prevented the application of the automotive components. The formability can be enhanced by conducting the warm hydroforming using induction heating device which can raise the temperature of the specimen very quickly. The specimen applied to the test is AA6061 extruded tubes which belong to the age-hardenable aluminum alloys. But in the case of AA6061 age hardening occurs at room temperature or at elevated temperatures before and after the forming process. In this study the effects of the heating condition such as heating time, preset temperature, holding time during die closing and forming time on the hydroformability are analyzed to evaluate the phenomena such as dynamic strain hardening and ageing hardening at high temperatures after the hydroforming process.

Development of Horizontal Reheating System for Semi-Solid Die Casting and Its Microstructure Evaluation

The parts manufactured by die casting process usually contain liquid segregation and porosities. To solve these problems, the semi-solid forming process has been applied. The process enables material in the semi-solid state to be completely filled, and parts with the complicated shape to be fabricated by applying relatively low pressure. This process is necessary in order to control the microstructure of the billet as well as to achieve the desired semi-solid billet state. In this study, a horizontal high-frequency induction heating device which can be fabricated by semi-solid forming irrespective of a billet's size was developed. A globular structure of the reheated billet and a billet's temperature distribution during the reheating process for A356 were investigated.

External heating of stents by radio waves: Pilot studies in rabbit aorta

Purpose: This experiment was designed to assess the feasibility of radio frequency energy delivered by a prototype radio frequency generator inductive heating device (REVAX) positioned external to the body, for transient heating of stents after arterial implant. Methods and Materials: Twenty-one New Zealand White rabbits underwent stenting of their infrarenal aorta. Nine rabbits were stented and immediately placed in the REVAX for external stent heating with internal temperature probes in place. Twelve rabbits were stented and 3 days later either heated or placed in the generator as a sham for 20 min. The animals were terminated 28 days later. Results: The REVAX was able to heat the aortic stents in a controlled fashion; in Phase II experiments, the stent temperature was raised to 42 °C for 20 min. In Phase I mild necrosis was noted at the stent struts. In Phase II, necrosis and mineralization of the media was seen at the stent struts, and evidence of neointimal suppression was observed. Conclusion: This study demonstrated that external heating of stents in a blood vessel in a live animal via radio frequency energy is feasible. Further studies will be needed to assess whether any specific heating regimen might inhibit fibrocellular neointimal hyperplasia.

Transverse flux induction heating: comparison between numerical models and experimental validation

This paper presents two numerical methods, which will be able to predict the temperature distribution in the thin moving conducting sheet, which is caused by the eddy‐current losses in transverse flux inductive heating devices (TFIH). The first method is based on a finite element calculation, while the second one is based on a circuit approach. The main aim of this paper is the validation of the circuit model by comparison with the more accurate and sophisticate finite element model. In addition, the results of both numerical models have also been compared with those obtained by experimental measurements.

Thixoforming characteristics of thermo-mechanically treated AA 6061 alloy for suspension parts of electric vehicles

Thixoforming trials of AA 6061 alloy, which is a wrought aluminum alloy, were undertaken to manufacture the steering knuckles designed for suspension parts of low speed electric vehicles. The billets used as a starting material were thermo-mechanically treated to induce thixoformable fine globular microstructures during subsequent reheating process. After a slug was reheated up to the working temperature (∼645 °C) using the horizontal induction heating device, the part was formed by vertical injection of a heated slug into the die cavity. The well-developed globular microstructures could be observed in most sections of the thixoformed parts except few surface regions close to gate where occasional unrecrystallized large grains are present. However, liquid segregation between near and far gate region could not be avoided, which was probably resulted from high injection speed. The reason for that will be explained using semi-solid characteristic flow behaviors and the method to reduce liquid segregation will be suggested. In order to evaluate the mechanical properties of AA 6061 thixoformed parts, a series of test specimens carefully classified by their cutting location in a part were used for tensile test. From tensile test results, it could be revealed that tensile properties were strongly affected by liquid segregation. Especially, variation of tensile properties was more dominant when the part was heat treated by T6 condition. These results may be attributed to the segregation of alloying elements such as Mg and Si caused by the segregation of liquid phase involving much alloying element. Therefore, it is necessary to reduce liquid phase segregation in order to obtain more uniform tensile properties. By comparing tensile properties of AA 6061 thixoformed parts to those of previously thixoformed parts made from cast grade A357 alloy, it was found that AA 6061 parts showed far better ductility, even though strength level is slightly lower, than A357 parts at both as-formed and T6 condition. In this study, it was confirmed that wrought aluminum alloy, AA 6061 has the reasonable thixoformability and mechanical properties for thixoforming of real parts such as steering knuckles.

Temperature solver for highly nonlinear ferromagnetic materials for thin moving sheets in transversal flux induction heating

In this paper, a successive iteration method has been applied to a highly nonlinear temperature problem. The nonlinearity arises from the specific heat of ferromagnetic materials. These materials are heat treated in transversal flux inductive heating devices (TFIH) as thin strips. The convergence behavior is examined and compared to the classical Newton-Raphson scheme. Additionally, a method will be presented which takes phase change energies of the material into account.

Magneto-thermo-elastic-plastic simulation of inductive heating of metals

The magneto-thermo-mechanical behavior of metals in inductive heating devices is investigated by means of numerical calculations. The goal of this paper is to attract attention to necessity of mechanical problems solution for inductive heating technology and to develop three-dimensional and two-dimensional (axisymmetrical) mathematical models, coupling algorithm and software for such computations. The paper presents a finite element formulation, based on an indirect coupling model of electromagnetic, thermal and static elastic-plastic mechanical processes in treated workpieces in inductive heating devices. The effect of electromagnetic, thermal and mechanical material properties depending on temperature is taken into account. The presented numerical technique is applied for technological problems of practical interest.

Electromagnetic induction heating device and image recording device

Electromagnetic induction heating device and image recording device

Electromagnetic forces in transverse flux induction heating

This paper deals with the numerical modeling of the electromagnetic field in transverse flux induction heating devices and with features of forces due to nonsymmetrical position of the sheet to be heated within the inductor air-gap. The results of four field computation models are compared. Three computation methods of the electromagnetic force acting on nonmagnetic and magnetic sheets are used. The influence of the horizontal and vertical sheet positions in the inductor air-gap is analyzed. A particular variation of the electromagnetic force with the field frequency is emphasized for magnetic sheets.

Optimal design procedure for a practical induction heating cooker

This paper presents a practical optimal design procedure for small induction heating devices. An experimental modeling of the physical properties and a practical simulation technique for the nonsinusoidal input waveform is adopted. The design sensitivity analysis with Levenberg-Marquardt method is used for the optimal design process. The proposed method is applied to an induction heating pan cooker model, and the result is verified by experiment.

Development of RF and microwave heating equipment and clinical applications to cancer treatment in Japan

Development of RF and microwave (MW) heating equipment for hyperthermia and their clinical applications to various cancers undertaken in Japan have been reviewed in this paper. Originally developed heating devices include an RF capacitive and RF inductive heating device, an MW heating device with a lens applicator, an RF intraluminal heating device, an RF current interstitial heating device, and a ferromagnetic implant heating device. The concept and characteristics of those devices are described herein. Nonrandomized and randomized trials undertaken for superficial and deep-seated tumors demonstrated improved local response with the combined use of hyperthermia. Furthermore, the complications associated with treatment were not generally serious, except for chronic bowel damages suggested in a trial for colorectal cancers. These clinical results indicate the benefit of combined treatment of hyperthermia and radiotherapy. With the advancement of heating and thermometry technologies, hyperthermia will be more widely and safely used in the treatment of cancers.

Field and temperature calculations in transverse flux inductive heating devices heating nonparamagnetic materials using surface impedance formulations for nonlinear eddy-current problems

This paper presents the calculation of both the field and temperature distribution in thin moving nonparamagnetic sheets in transverse flux inductive heating devices (TFIH). The surface impedance formulation for nonlinear materials is extended to this thin plate problem. The temperature distribution is obtained by solving Fourier's thermal conduction equation. In this nonlinear coupled electromagneto-thermal problem the temperature dependencies of the B/H curve, the conductivity and the thermal conductivity are fully considered.

Prediction of the eddy-current and temperature distribution in a TFIH device using neural networks in order to improve the convergence of the finite element calculations

This paper presents a method of predicting the eddy-current distribution in transverse flux inductive heating devices (TFIH) with the help of one neural network. A second neural network is used to obtain the temperature distribution in the thin moving conducting sheet caused by the eddy-current losses. Both solutions are initial solutions for the finite element calculations of this nonlinear coupled electromagneto-thermal problem.