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Computer Modeling [.pdf format]

A common misassumption in induction hardening

Authors: Valery Rudnev
Publication: Heat Treating Progress, Professor Induction Series
Date: 9/1/2004

Whenever someone is talking about induction heating, reference is often made to the phenomenon of skin effect. In most publications devoted to induction heating distributions of current density and power density (heat source distributions) along the workpiece thickness/radius are simplified, and described as exponentially decreasing from the surface into the workpiece. However, in some applications, surface hardening in particular, the power density distribution along the radius/thickness has a unique "wave" shape, which differs significantly from the commonly assumed, classical exponential distribution. Here, the power density is maximum at the surface, and decreases toward the core. But then, at a certain distance from the surface, the power density increases, reaching a maximum value before again decreasing. Article discusses frequency selection for induction surface hardening as well as electromagnetic "wave" phenomenon.

A fresh look at induction heating of tubular products: Part 2

Authors: Valery Rudnev
Publication: Heat Treating Progress, Professor Induction Series
Date: 7/1/2004

Part 2 focuses on selective induction heating of tubular products. Applications made possible by induction's ability to concentrate the heat within a specific area of a workpiece include localized stress relieving, brazing, parting, friction welding, bending, annealing of welds, etc.

Electromagnetic forces in induction heating

Authors: Valery Rudnev
Publication: Heat Treating Progress, Professor Induction Series
Date: 7/1/2005

Electromagnetic (EM) forces play the major part in many modern technologies. Motors, magneto-hydro-dynamic (MHD) seals, electromagnetic pumps, levitators, electrical bearings, and springs are some of the modern technologies in which EM forces play a leading role. In some applications, EM forces can reach tremendous values. For example, thanks to a capability to develop incredibly large electromagnetic forces, electric guns or launchers can fire materials to higher velocities than are achievable by rockets or chemical/powder guns. In the majority of induction heating applications, coil current also can reach appreciable values. For example, currents of 10 kA and higher are not unusual for many induction heat treating applications including shaft hardening and gear hardening. High currents produce significant forces that have a pronounced effect on coil life. Without proper consideration, those forces can physically move the heated workpiece, flux concentrator, and even bend induction coil, or fixture, which may negatively affect overall system's reliability and repeatability as well as dramatically reduce a coil life. Unfortunately, electromagnetic forces are rarely discussed in induction heating publications. Endless variety of heat treated parts required a specific coil geometry adds a difficulty to study EM forces. This column is intended to at least partially remedy this by providing an introduction to the topic.

Common Misinterpretations and Confusion Appearing in Induction Heating Publications. Presentation of New Handbook of Induction Heating

Authors: Valery Rudnev
Publication: Proceedings of International Scientific Colloquium "Modelling of Electromagnetic Processing", Hannover, Germany
Date: 3/24/2003

During numerous discussions with users of induction heating technology we found that quite often some of them misinterpreted certain interrelated aspects involved in this process. One of the reasons for this is the fact that quite often descriptions of particular phenomena are contained in a variety of internal reports, scientific journals, or literature specializing in a particular (typically quite narrow) area. Some of these materials have been presented in a form that is nearly inaccessible to readers. In the newly published Handbook of Induction Heating, an attempt has been made to continue the tradition of classical texts devoted to this process to educate the wide range of the specialists involved in this technology. Another goal of this handbook is to embark upon the next step in the study and design of modern induction heating processes and equipment. An attempt has been made to bridge the gap between advanced theoretical information and information which is of concrete and practical use to the induction heating practitioners. Thus, there is a hope that this 800-page handbook will serve the industry as a complete contemporary guide to induction heating. Some of the subjects discussed in this handbook are indicated below.

The use of diacoptics method for modeling of induction heating systems

Authors: Valery Rudnev
Publication: Proceedings of Int. Symposium "Heating by Electromagnetic Sources", Italy
Date: 5/1/2004

Article discusses some subtle theoretical aspects of mathematical modeling applied for development computer modeling software for induction heating.

Spin hardening of gears revisited

Authors: Valery Rudnev
Publication: Heat Treating Progress, Professor Induction Series
Date: 3/1/2004

In recent years, gear manufacturers have gained additional knowledge about how technology can be used to produce quality parts. The application of this knowledge has resulted in gears that are quieter, lighter, and lower cost, and have an increased load-carrying capacity to handle higher speeds and torques while generating a minimum amount of heat. Not all gears are well suited for induction hardening. For example, bevel, hypoid, and noncircular gears are rarely heat treated by induction. On the other hand, external spur and helical gears, worm gears, and internal gears, racks, and sprockets are among those that typically are induction hardened. Frequency selection and computer modeling of induction hardening of gears is discussed here.

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