| 摘要 |
An induction heater has an electrical conductor 40 extending along an axis B. At least one solid heating element 43 for contacting and transferring heat to a material to be heated extends radially from the axis B and is formed of electrically conductive and preferably ferromagnetic material. An alternating electric current is supplied to the electrical conductor 40 to induce an electric current in a closed loop defined by a surface layer of the or each heating element 43 to generate heat therein. Induced eddy currents are confined to a surface layer due to the skin effect. The radial and axial thickness of the heating elements 43 is greater than twice the skin depth of the electrically conductive material at the frequency of the alternating electric current. Preferably the heating element 43 is in the form of a screw arranged on the outside or inside of an electrically conductive heating member 42. <IMAGE> |
