High Frequency Induction Research Articles

Three-dimensional numerical study of heat-affected zone in induction welding of tubes

Purpose Quality of the weld joint produced by high-frequency induction (HFI) welding of steel tubes is attributed to a number of process parameters. There are several important process parameters such as the speed of the welding line, the angle of the approaching strip edges, the physical configuration of the induction coil, impeder, formed steel strip and weld rolls with respect to each other, the pressure of the weld rolls and frequency of the high-frequency current in the induction coil. The purpose of this paper is to develop a 3D model of tube welding process that incorporates realistic material properties and movement of the strip. Design/methodology/approach 3D numerical simulation by the finite element method (FEM) can be used to understand the influence of these process parameters. In this study, the authors have developed a quasi-steady model along with the coupling of electromagnetic and thermal model and incorporation of non-linear electromagnetic and thermal material properties. Findings In this study, 3D FEM model has been established which gives results in accordance with previously published work on induction tube welding. The effect of the Vee-angle and frequency on the temperature profile created in the strip edge during the electromagnetic heating is studied. Practical implications The authors are now able to simulate the induction tube welding process at a more reasonable computational cost enabling an analysis of the process. Originality/value A 3D model has been developed for induction tube welding. A non-linearly coupled system of Maxwell’s electromagnetic equation and the heat equation is implemented using the fixed point iteration method. The model also takes into account non-linear magnetic and thermal material properties. Adaptive remeshing is implemented to optimise mesh size for the electrical skin depth of induced current in the strip. The model also accounts for the high welding-line speeds which influence the mode of heat transfer in the strip.

高周波誘導加熱エネルギー入出力の線形性に着目した「機能性評価法」による汎用モーター部品生産プロセスの最適化

高周波誘導加熱エネルギー入出力の線形性に着目した「機能性評価法」による汎用モーター部品生産プロセスの最適化

Minimum Loss Operation and Optimal Design of High-Frequency Inductors for Defined Core and Litz Wire

This paper studies the loss-optimal design of a power inductor employed in a 2 kW, 400 V input DC–DC converter. The design of an inductor is subject to a large number of design parameters and the implications of the different design parameters on the losses are often not clearly traceable in a full optimization, e.g., different current ripple amplitudes can lead to designs with similar losses, as larger ripple amplitudes lead to increased AC core and winding losses but lower DC losses in the winding due to lower inductance values and/or numbers of turns. In an effort to achieve a comprehensible description of the implications of the key design parameters (switching frequency, $f_\text{s} $ , current ripple, r , number of turns, N ) on the losses, the remaining parameters, e.g., core (E55/28/21 N87) and type of conductor (litz wire), are considered to be given. In a first step, the investigation is based on a simplified analytical model, which is refined in a step-by-step manner, e.g., to consider core saturation. In a second step, the implications of further critical aspects on the losses, e.g., temperatures of core and coil, are examined using a comprehensive semi-numerical model. Surprisingly, the evaluation of the losses calculated in the $f_\text{s}$ – $r$ domain reveals that nearly minimum inductor losses are obtained for a current ripple that is inversely proportional to the frequency, i.e., for a constant inductance, within a wide frequency range, from 200 kHz to 1 MHz. Furthermore, the investigation reveals a decrease of the losses for increasing frequencies up to 375 kHz, e.g., from 4.32 W at 80 kHz ( r = 110 %) to 2.37 W at 375 kHz ( r = 18 %). The detailed analysis related to these results enables the compilation of a simple two-equation guide for the design of an inductor that achieves close to minimum losses. In a next step, interesting trade-offs are identified based on a study of the design space diversity, e.g., with respect to low cost and increased partial-load efficiency. The findings of this work are experimentally verified, i.e., the losses of three different inductors are measured with an accurate calorimetric method and at four different frequencies, ranging from 150 kHz to 700 kHz.

Characteristic Evaluation of Coaxial High-Frequency Induction Heating Hybrid Friction Stir Welding Process on High Strength Carbon Steel Sheets

The thermo-mechanical properties of high strength steel limit the use of the friction stir welding(FSW) process in terms of quality and productivity. In this study, hybrid FSW(HFSW) using coaxial induction heating was designed to be applied to high strength steel and to ensure directional flexibility. The performance and characteristics of the HFSW process were evaluated on 590 and 980 dual phased high strength steel. The range of welding speeds adequate for the FSW and HFSW processes were compared, to evaluate the productivity of the HFSW process. During FSW, system deflection, vertical load and torque were measured to understand the process behavior. In HFSW, welding speeds were increased by 75% and 50%, respectively, for 590 DP and 980 DP steels compared to the conventional FSW processes. Furthermore, a relatively deeper heat-affected zone was achieved. The deeper heat-affected zone was produced by deeper tool plunging depth due to reduced system deflection. Earlier stabilization of the vertical load and torque is another feature of HFSW, due to the preheating effect. Employing the HFSW process, with its simple system configuration and process flexibility, can improve productivity and quality for welding high strength steels. Key words: Coaxial high-frequency induced heating, Friction stir welding, Dual phased high strength steel, Welding speed, Vertical load, Torque

Synthesis of powder metallurgy Ti-3Fe-2Al alloy using high-frequency induction heating

A powder metallurgy approach was applied for the synthesis of an [Formula: see text] Ti-2Al-3Fe alloy. Blends of the elemental Ti, Al and Fe powders were compacted and subsequently sintered. High-frequency induction heating (HFIH) instead of conventional high-vacuum furnace heating was used for the sintering, due to its high efficiency. The effect of temperature on the level of densification, residual porosity and mechanical properties was studied. Electron dispersive spectrum analysis was used to study the dissolution and homogenization of the alloying elements. The results showed that a short induction sintering (IS) cycle in the range of 10–15 min is sufficient to achieve significant powder consolidation, evident by the increase of the density and mechanical properties. The residual porosity diminishes with the increase of the sintering temperature. Full dissolution of the alloying powders is completed after sintering at temperatures above those of [Formula: see text]- to [Formula: see text]-phase transformation.

Comparative Analysis of Magnet Thermal and Magnetization State Monitoring in PMSMs Based on High-Frequency Signal Injection

Thermal and magnetization state monitoring of permanent magnet synchronous machines (PMSMs) is important for reliability purposes. Use of magnet high-frequency (HF) resistance has been proposed both for thermal and magnetization state monitoring, as it directly depends on PM temperature and magnetization state. Machine d -axis HF inductance has been recently proposed for thermal state monitoring, though its use for magnetization state estimation remains to be explored yet. This article reviews the use of HF-signal-injection-based methods for thermal and magnetization state monitoring on PMSMs, including the use of the HF inductance for magnetization state monitoring.

Study on microstructure and properties of high frequency induction cladding TiC/Ni coating after solution treatment

To improve the performance of the 35CrMo sucker rod during operation, the microstructure, microhardness and wear properties of the TiC/Ni-based composite coating prepared by induction high frequency cladding at different solution treatment temperatures were investigated. The results show that the coating consists mainly of γ-Ni, Ni3Fe, Cr23C6, CrB, TiC, SiB6, NiCr2O4 and Fe2O3 phases after solution treatment. The average microhardness of the coating increased from 835.7 HV0.2 before the heat treatment to a maximum of 890.3 HV0.2, an increase of 6.5%. The wear resistance of the coating increases first and then decreases with the increase of solution treatment temperature. When the solution temperature is 950 °C, the wear resistance is best. The wear mechanism of the coating and friction pair is mainly adhesive wear and abrasive wear, and accompanied by brittle fracture.

Mechanical Properties and Fabrication of a Nanostructured Nb-Al2O3 Composite by High Frequency Induction Heating

Al2O3 has a high Young’s modulus (380 GPa), a low density (3.98 g· cm-3), good high-temperature mechanical properties, biocompatibility and excellent oxidation resistance. Al2O3 has been used for automotive, aerospace, bio-materials and various industrial applications. Despite its various merits, the low fracture toughness of the material below the brittle-ductile transition temperature has limited its use for wide application. To enhance its fracture toughness, the method commonly utilized has been to make a composite by the addition of a second phase to fabricate nanostructured materials. In the study, nano-powders of Al2O3 and Nb were synthesized during the ball milling according to the reaction(Nb2O5 + 10/3 Al → 2Nb + 5/3 Al2O3). The nanostructured Nb-Al2O3 composite was consolidated within a short time from the milled powders using high-frequency induction heated sintering. The average grain sizes of Al2O3 and Nb in composite sintered at 1400 °C were 63 and 250 nm, respectively. The relative density of the Nb-Al2O3 composite was about 99% under the simultaneous induced current and application of 80 Mpa pressure. The fracture toughness and hardness of the composite were about 8.7 MPa· m1/2 and 1460 kg/mm2, respectively. The fracture toughness of the nanostructured Nb-Al2O3 composite was higher than that of monolithic Al2O3. (Received June 7, 2019; Accepted September 10, 2019)

Energy Efficient Processing of Geotermal Water for Energy-Heating Objects of the Building Industry

Due to the energy crisis in Ukraine, the problem of significant increase in the efficiency of production, transportation and use of energy is of particular importance. Considering the significant role in energy supply of the country, the issues of efficient use of heat energy in all areas of these systems are solved: generation for heating water or for steam generation; transportation to the consumer, as well as when using it by the consumer. On the heat exchange surfaces of the systems, scale occurs, which leads to deterioration of heat and mass transfer processes and heat energy indices [6]. This affects the overall performance of the process. In this paper, the question of determining the parameters of an electromagnetic field in the process of treatment of pure water is solved and physical models of the change of the structure of pure water after treatment in the electromagnetic field and the change in the nature of its interaction with different surfaces are developed. To improve the efficiency of the system perform preliminary cleaning and softening water before feeding it to the heat pump by the method of processing it in fields of constant current and in the field of permanent magnets. Next, filtration and water treatment in the field of electromagnets with certain parameters of high frequency of electric current and field induction are carried out. The scientific principles of changes in structural and thermophysical properties of water, ecological and technical technologies, which include the implementation of its basic principles, in which environmental and anthropogenic factors perform a functionally unifying role, are developed.

High-frequency induction heating for increase of flow length in polymer/metal hybrid molding

Recent trends of miniaturization and multi-functionality in electrical parts have driven development of molded interconnect devices (MIDs) that contain conductive tracks on a nonconductive base. This study aims to develop polymer/metal hybrid molding technology to fabricate MIDs in a single manufacturing process, without an additional assembly procedure. For this purpose, injection molding was performed to fabricate a thermoplastic carrier that contained negative circuit channels, and die casting was used to fill the circuit channels with metal alloy of low melting point. To increase the flow length of the molten metal through the narrow circuit channel, high-frequency induction heating was used prior to the die casting stage. The effect of heating conditions on the mold temperature was investigated numerically, and the relevant induction heating conditions were determined accordingly. Induction heating was then applied to the die casting process to increase the flow length enough to be used as a circuit path for fabrication of MIDs.

High-frequency induction heating of shrink-fitting parts of turbogenerators

The advantages and disadvantages of induction heating by high-frequency currents during large-sized parts mounting and dismounting are studied. The deviations of the temperature field and the deformation field of the part from the axial symmetry with the horizontal position of the shaft are analyzed. Recommendations were developed on how to take into account these deviations in the technology of mounting and dismounting of the retaining rings of turbogenerators.

Evaluation of a High-Frequency Induction Heating Assisted Friction Stir Welding Process on Carbon Steel Sheets

Friction stir welding of carbon steel causes tool wear and system deformation issues because of its relatively high strength compared to aluminum. As a countermeasure, additional high-frequency induction heating is suggested to solve this problem. An inline high-frequency induction heating assisted friction stir welding process was studied on 450 MPa and 980 MPa grade carbon steel sheets. As a pre-experiment, the heating performance of the high-frequency induction heating system was quantified. Then the effective welding speed range, vertical load history, and weldment performance were investigated to evaluate the characteristics of the process. Those results were compared with a conventional friction stir welding process conducted under equivalent process conditions. For the 440 MPa steel, about 40% faster maximum welding speed was achieved by applying the 4 kW induction heating. No tensile strength degradation of the weldment was found. Also, the maximum vertical load was decreased by 26% compared to the conventional friction stir welding process. No significant degradation of hardness was observed in the welds on 440 MPa and 980 MPa steel. Key words: High-frequency induced heating, Friction stir welding, Carbon steel, Welding speed, Vertical load

Role of doped nitrogen and sulphur in cobalt/cobalt-zirconium nanoferrites synthesized by facile methods

Nitrogen/sulphur doped cobalt and cobalt zirconium mixed nanoparticles were synthesised by coprecipitation/wet impregnation methods. X-ray diffraction and X-ray fluorescence spectroscopic studies reveal the formation of monophasic cubic spinel structure with expected stoichiometries. Average crystallite sizes vary in the range of 17–26 nm. X-ray photoelectron and energy dispersive X-ray spectroscopic studies indicate the successful incorporation of non-metal elements into the ferrite lattice. Fourier-Transform infrared and Raman spectroscopic studies confirm the presence of stable cubic spinel ferrite structure of cobalt ferrite after doping. Evidences point towards the insertion of sulphur and nitrogen as cations, contrary to other metal oxides like titania. Thermal stability studies prove that ferrite formation is a continuous process producing stable crystalline spinel nanoparticles around 700 °C. Magnetic measurements at room temperature indicate decrease in saturation magnetisation with doping whereas coercivity increases with reduction in the particle size. DC resistivity measurements in the range of 30–400 °C show decrease in resistivity with increase in temperature, indicating semiconducting behaviour. The results of microstructural, magnetic and dielectric properties suggest that the prepared nanoparticles are suitable for catalysis, adsorption recycle, high frequency devices, inductors and biomedical applications.

Crystal Structures and Electrochemical Properties of R1.5Ca1.5MgNi14(R=Nd, Gd and Er) Hydrogen Storage Alloys

Ca3MgNi14, Nd1.5Ca1.5MgNi14, Gd1.5Ca1.5MgNi14 and Er1.5Ca1.5MgNi14 alloys were prepared by high frequency induction melting and sintering. Characterization and analysis were performed by X-ray diffraction/Rietveld full-spectrum fitting, gaseous P-C-T hydrogen storage test and electrochemical properties tests. It can be found that all alloys consist of Gd2Co7-type 3R phase and Ce2Ni7-type 2H phase. Although the hydrogen storage capacities of Nd1.5Ca1.5MgNi14, Gd1.5Ca1.5MgNi14 and Er1.5Ca1.5MgNi14 decrease to some extent compared to that of Ca3MgNi14, their equilibrium pressures for absorption and desorption increase markedly. Moreover, R1.5Ca1.5MgNi14 alloys have better cycling stabilities and high-rate discharge(HRD) properties as compared to Ca3MgNi14. The hydrogen diffusion in alloy electrodes is the main factor to influence the HRD performance.

Corrosion Resistance of Zn-Al-Mg Alloys with Hypoeutectic Microstructure

Zn-Al-Mg alloys with hypoeutectic microstructure were melted through a high frequency induction furnace. The content of aluminum and magnesium in the alloys were between 1% to 2%. Scanning electron microscopy (SEM) was utilized to analyze microstructure and phase, respectively. Effect of alloying element contents on corrosion resistance was studied. Results show that the Zn-Al-Mg alloys are almost covered by primarily solidified Zn rich block phase and fine lamellar binary and ternary eutectic microstructure exist between the Zn rich phase. The corrosion resistance was characterized through electrochemical test which indicates that increasing Al and Mg content in the Zn-Al-Mg alloys decline corrosion current density. For alloys with 1% Al, more magnesium means lower corrosion potential. For alloys with 2% Al, however, more magnesium suggests higher corrosion potential. In Nyquist curves of electrochemical impedance spectroscopy (EIS) test, Warburg impedance portion could be found for all alloys. With increasing alloying elements content in the Zn-Al-Mg alloys, charge transfer resistance in higher frequency remarkably increase, which implies higher corrosion resistance.

Peach Tree Pollen and Prunus persica 9 Sensitisation and Allergy in Children and Adolescents

Background: Although plant and fruit pollens are entomophilous and relevant in exposed workers, we have shown a high frequency of sensitisation and symptoms induction of peach tree pollen (PTP) and Prunus persica 9 (Pru p 9) in adults from areas of peach cultivars. Methods: We studied the sensitisation and clinical relevance of PTP and Pru p 9 in a large group of children and adolescents aged 3–19 years. A detailed questionnaire plus skin prick testing to prevalent allergens, PTP, and Pru p 9 were carried out. The clinical relevance was established by nasal provocation test (NPT) and symptom score index. Results: We evaluated 685 children (mean age 8.75 ± 3.3 years, median 9 years), 52% of them female. Sensitisation to PTP occurred in 20% of the cases following olive tree (33%) and Phleum pratense (26%). In a randomly selected subgroup of subjects sensitised to PTP, 30% were skin prick test-positive to Pru p 9. Most cases had rhinitis or rhinoconjunctivitis. NPT showed the relevance of PTP and Pru p 9 in the induction of symptoms. Conclusion: PTP and Pru p 9 are relevant in the induction of sensitisation and respiratory symptoms in children and adolescents. This allergen should be evaluated in children living in regions of peach tree cultivars.

The Microalloying Effect of Ce on the Mechanical Properties of Medium Entropy Bulk Metallic Glass Composites

Novel ultra-strong medium entropy bulk metallic glasses composites (BMGCs) Fe65.4−xCexMn14.3Si9.4Cr10C0.9 and Ti40−xCexNi40Cu20 (x = 0, 1.0), through the martensite transformation induced plasticity (TRIP effect) to enhance both the ductility and work-hardening capability, were fabricated using magnetic levitation melting and copper mold suction via high frequency induction heating. Furthermore, the Ce microalloying effects on microstructure and mechanical behaviors were studied. The Fe-based BMGCs consisted of face-centered cubic (fcc) γ-Fe and body-centered cubic (bcc) α-Fe phase, as well as Ti-based BMGCs containing supercooled B2-Ti (Ni, Cu) and a thermally induced martensite phase B19’-Ti (Ni, Cu). As loading, the TRIP BMGCs exhibited work-hardening behavior, a high fracture strength, and large plasticity, which was attributed to the stress-induced transformation of ε-Fe martensite and B19’-Ti (Ni, Cu) martensite. Ce addition further improved the strengthening and toughening effects of TRIP BMGCs. Adding elemental Ce enhanced the mixing entropy ΔSmix and atomic size difference δ, while reducing the mixing enthalpy ΔHmix, thus improving the glass forming ability and delaying the phase transition process, and hence prolonging the work-hardening period before fracturing. The fracture strength σf and plastic stress εp of Ti39CeNi40Cu20 and Fe64.4CeMn14.3Si9.4Cr10C0.9 alloys were up to 2635 MPa and 13.8%, and 2905 MPa and 30.1%, respectively.

One-step rapid preparation of CuO nanosheets by high frequency induction heating and the application as excellent electrochemical sensor based on CuO/MWCNTs for the detection of glucose

In this study, to improve production efficiency, a simple and rapid synthesis method of copper oxide (CuO) nanosheets by using high frequency induction heating was proposed. The CuO nanosheets were successfully prepared, and formulated into CuO and CuO/Multi-walled carbon nanotube (MWCNTs) electronic ink. After characterizing of the morphology, composition and structure of the as-prepared CuO nanosheets, the non-enzymatic glucose sensors by using CuO nanosheets and CuO/MWCNTs as functional materials were fabricated by dispensing on screen printed graphite electrodes (SPGE). For the detection of glucose, the electrochemical properties of the fabricated electrochemical sensor were evaluated by cyclic voltammetry (CV) and chronoamperometry. The results showed that the prepared electrochemical glucose sensor by CuO and CuO/MWCNTs all exhibited excellent sensitivity (1290 μAmM−1cm−2, 1890 μAmM−1cm−2), wide linear range (4–400 μM), and low detection limit (0.21 μM, 0.14 μM), high selectivity to common interference in physiological fluids, high stability and excellent feasibility for actual sample analysis. Between them, the electrochemical properties of the sensor prepared from CuO/MWCNTs are better due to the excellent electronic conductivity of MWCNTs.

A Universal High-Frequency Induction Machine Model and Characterization Method for Arbitrary Stator Winding Connections

High-frequency modeling of induction machines plays an important role in investigating motor drive electromagnetic interference issues such as stator winding reflected-wave overvoltage and bearing discharging current. Characterization of high-frequency machine models requires measurements of machine's differential-mode (DM) and common-mode (CM) impedances up to tens of MHz. The machine's stator winding connections, e.g., single-, and series-, parallel-winding Y/Δ configurations, influence the measured DM and CM impedances and model parameters. In this paper, a universal high-frequency equivalent circuit model capable of representing induction machines with arbitrary stator winding connections is proposed. The new model features a simple structure with a straightforward characterization method. Specifically, only one stator winding configuration is required for impedance measurements to fully characterize the machine model for arbitrary stator winding connections. The proposed methodology is demonstrated using a 7.5 hp dual-voltage nine-terminal/lead induction machine and a drive system. The simulated DM and CM impedances as well as the motor overvoltages show excellent agreement with the experimental results. The proposed model and characterization method represent significant improvement in terms of accuracy, applicability/generality, and convenience compared to prior conventional models.

Advancement in the Pressureless Sintering of CP Titanium Using High-Frequency Induction Heating

High-frequency induction heating is applied as an alternative heating source for pressureless sintering of commercially pure Ti powders, aiming to intensify the sintering process. The effects of the process parameters on the properties of the sintered material are systematically studied. The initial powder compact density is the most influential parameter permitting sintered structures with highly porous to almost fully dense appearance. Short heating time combined with sintering to temperatures just above the β-transus resulted in a strong diffusion bonding between the Ti powder particles, and grain growth is observed at the former boundaries of the neighboring powder particles. The dimpled appearance of the fracture surface at those regions confirmed the strong metallic interparticle bonding. Tensile properties comparable to those of Ti-Grade 3 and Ti-Grade 4 are achieved, which also demonstrates the efficiency of the induction sintering process. A mechanism explaining the fast and efficient sintering is proposed. The process has the added advantage of minimizing the oxygen pickup.