Patent ID: 7022951

Claim:
An induction heating device for heating electroconductive material to a desired temperature, said device having a heating end with an opening disposed proximate to the material during heating of the material, said device comprising: an open core comprising U-shaped body of magnetic material having a pair of legs and a pair of edges located at ends of the legs, said edges being separated by space and being disposed at the opening in the heating end of the device; coils of electrically conductive material wound separately on the legs of the U-shaped body, respectively, said coils for simultaneously receiving in parallel a current to excite each of said coils, said legs becoming the pole pieces of magnetic flux concentrator whenever said excitation current is passed through said coils in parallel to produce a variable magnetic field of very high flux density in the space between the two edges, facing each other, at the ends of the two poles, and closest to the material being heated; and wherein each of said coils is wound around each leg in a direction such that on excitation, when one leg becomes the N pole of said flux concentrator the other leg becomes the S pole of said concentrator, said legs alternating in polarity when said excitation current alternates in polarity, thereby forcing the magnetic flux to pass between the edges at the ends of the pole pieces, facing each other, and through said material to be heated.