GB889940A - Improvements in, or relating to, electric induction heaters - Google Patents

Abstract

889,940. Induction heaters. A.E.I.-BIRLEC Ltd. March 7, 1958 [Dec. 7, 1956], No. 37414/56. Class 39(3) An induction heater comprises a transformer having a secondary winding the ends of which are connected to corresponding ones of two parallel adaptor plates having marginal zones located between two halves of two or more split inductor units so that by moving the two halves of any one of the units into contact with one another and with corresponding ones of the said plates, a circuit is completed through the winding plates and unit. As shown, an induction heater comprises a partition 1 on one side of which is mounted a transformer 2 consisting of a multiturn primary and a single-turn secondary in the form of a copper shell 10 with a longitudinal split 11, a pair of parallel adaptor plates 3, 4 mounted on the other side of the partition and electrically connected to the respective ends of the secondary and insulated one from the other, and three split inductor units (Fig. 1 not shown) each of which can be opened and closed by a corresponding actuating mechanism which includes a toggle linkage. The marginal zone of each adaptor plate is formed with three arms 21, 22 and 23, corresponding to the number of inductor units, each having a silver contact pad 24, the corresponding arms 21 and 23 of each plate being so shaped as to form between them an eye 25 into which a metal plug may be inserted to vary the power absorbed by the corresponding inductor unit without affecting the power absorbed by the other unit. Each inductor unit comprises two halves 33,34 each having contact pads 64 and 65 so that in the closed position, wherein the halves embrace a workpiece to be heated, the pads 64 seat on the pads 24 of the adaptor plates and the pads 65 seat one upon the other thereby closing a circuit through the secondary winding, the adaptor plates, and the inductor unit. The halves 33, 34 are pivotally mounted in boxes 40 and 36 which are themselves mounted upon a pair of axially reciprocable rods 30, box 36 being fixed to the rods and box 40 being slidable relatively to and longitudinally of the rods and being coupled to the rods through a toggle linkage consisting of pairs of arms 42 and 43 the elbows of which are pivoted upon a pin 46 guided in a slide 47 for reciprocal movement along a path parallel to the adaptor plates to impart simultaneous movement in opposite directions to the inductor halves so that they are brought together, the drive to the toggle elbow being effected by the piston rod 51 of a hydraulic or pneumatic cylinder 50..