GB365873A - Improvements relating to induction or reactance coils - Google Patents

Abstract

365,873. Stirring molten metals. ELECTRIC FURNACE CO., Ltd., 17, Victoria Street, London.-(Assignees of Northrup, E. F. ; Ajax Park, Trenton, New Jersey, U.S.A.) March 23, 1931, No. 8857. Convention date, March 26, 1930. [Class 86.] In an inductance coil for electric induction furnaces, the ampere turns per unit axial length are graded by spacing the turns, either directly, or by grading the cross section of the conductor forming the coil, and this grading controls the stirring of the charge. A water-cooled inductance coil, Fig. 1, formed of tubing 12, is graded by flattening the tubing at rightangles to the axis of the coil at its ends 13 so as to provide maximum ampere turns per unit length at these parts, the turns 14 at the centre of the coil being flattened parallel to its axis and the intermediate parts 12 being circular. The distance between adjacent turns is kept constant. In an induction furnace of the coreless type, Fig. 6, the coil 15 may be of uniform cross section with the turns spaced to give maximum flux density at the top of the crucible 20, the charge being then vigorously stirred at the surface. Stirring may be reduced by concentrating the winding at the bottom, or, by concentrating the winding at both top and bottom of the crucible, an intermediate effect may be obtained. Power factor correction is effected by a condenser 19.