ASM 2001 Influence of Magnetic Flux Controllers on Induction Heating Systems
Influence of Magnetic Flux Controllerson Induction Heating Systems, Computer Simulation and Practice Robert T. Ruffini, President Fluxtrol Manufacturing, Inc. Auburn Hills, MIDr. Valentin S. Nemkov, Chief Scientist; Robert C. Goldstein, Research Engineer Centre for Induction Technology, Inc. Auburn Hills, MI
Overview• Magnetic Flux Control in Induction Heating• Magnetic Flux Controller Application Technique• Examples of Induction Coils with Magnetic Flux Controllers• Conclusions• Robot Guided Induction Heating Application
Technological Effects of MFC Application• Improved induction coil efficiency• Better utilization of the workpiece power• Magnetic field and heat pattern control• Protection against unintended heating• Improved power supplying circuitry performance• Elimination of external magnetic fields
Materials for Magnetic Flux Control• Laminations 2 Laminations 1.6 MDMs• Ferrites 1.2 Flux Density (T) 0.8• Magnetodielectric 0.4 Ferrites Materials (MDMs) 0 0 50 100 150 200 250 Magnetic Field Strength (A/cm) B-H Curves for MFCs
Considerations for MFC Selection• Relative magnetic permeability• Operating frequency• Core Losses• Thermal resistance• Ease of installation and removal• Machinability• Electrical resistivity• Chemical resistance• Cost
Magnetic Permeability ofMDM’s for Induction Heating 150 125 100 Fluxtrol A Permeability 75 50 Fluxtrol A 25 Fluxtrol B Ferrotron 0 0 50 100 150 200 Magnetic Field Strength (A/cm)
How to Apply MDM’s to Induction Heating Coils• Epoxy/Glue/Adhesive MFC to Copper Coil – Prepare copper surface by removing machining oil or residual quenchant – Use thermally conductive, electrically non conductive epoxy – Use epoxy with high temperature and thermal shock resistance• Mechanically Fasten – Soft solder or braze a brass bolt to copper inductor and drill clearance hole in MFC – Use a thermally conductive grease between copper coil and MFC• Soft Solder (Fluxtrol A)
Conclusions• Magnetic Flux Controllers Are an Important Part of the Induction Technique• Examples of Induction Heating Coils with MDM controllers applied were shown• Computer Simulation Can Accurately Predict the Performance of Magnetic Flux Controllers
Robot Guided Induction Scanning Application Demonstrates:1. The ability to treat complex shape parts with induction robotic technique2. Modern induction equipment suitable for robotic scanning3. Ability of computer simulation to predict the results of heating4. Demonstration of the magnitude of magnetic flux controller influence
Demonstration Stand1. Workpiece - S-shaped 1/2” thick steel plate water-cooled on the back side2. Specially designed hair-pin coil with Fluxtrol Amagnetic flux controller applied3. ABB industrial robot4. Hand-hold coaxial transformer with a flexible cable(EFD)5. EFD power supply Minac: 30 kW, 10 - 25 kHz6. Close loop cooling system (Dry Coolers, Inc.)
Induction Coil ComparisonCoil without a concentrator Coil with Fluxtrol A concentrator
Robot Guided Induction Scanning Conclusions• Magnetic Flux Controllers Make a Dramatic Effect on Hair-Pin Coil Performance• Computer Simulation Allows the Designer Accurately Predict the System Parameters and Heating Results• Robotic Scanning Systems Can Be Used Effectively in Flexible Production Line
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