Patent GB-560630-A (GB)
Title: Improvements in or relating to induction heating apparatus
IPC: F27D11/06
Filed: 1942-03-23
Abstract: 560,630. Cooling systems. BUDD INDUCTION HEATING, INC. March 23, 1942, No. 3852. Convention date, March 21, 1941. [Class 64 (iii)] [Also in Groups XI and XII] A workpiece is heated by electromagnetic induction by placing it within a helical coil in which it is supported by angularly spaced longitudinal rails which are water cooled. The coil 40, Fig. 3, is formed of a hollow conductor of square section, each turn being insulated by mica or varnish-impregnated tape. The coil is wound over a mandrel covered with mica or other insulation, and is further insulated at the ends with " Bakelite " (Registered Trade Mark) or other rings. Longitudinal strips of " Bakelite " 69 are placed on the outside of the coil and bound with insulating tape. An inner lining of longitudinal firebrick segments 74 includes water-cooled work-supporting rails 76 between the segments, held in place by clips 79. The rails are held radially outwardly by end and middle supports, the latter comprising an expanding ring of sheet metal formed of wings of sheet metal welded to the rails and clamped together adjustably. The end supports of the rail comprise radial studs 83 and screw hooks 86. The securing clips 79 are not continuous but are separated by an interposed series of workpiece supports 88. The firebrick lining and rails 76 may be removed from the heating coil 40 by removal of the end supports. The segments 75 of the lining may be axially withdrawn separately if required. The coil 40 is supported by clamps 98, Fig. 4, the base of each of which is provided with extensions 100, 101 to receive studs 102, 103 below the coil. The clamp 98 is pivoted at 106 and carries an adjusting stud 108. Coils 40 of different diameters may be accommodated. The arm 101 carries the bus-bars 116 which supply the current, connected with bus-bars 53 below, each arranged in the form of a horizontal rectangle. The bars 53 are supplied from concentric conductors 128, which are also connected, through concentric risers 129, to the connectors 133 and thence to the bus-bars 116. The bars 53 are also connected to banks of condensers 56, means being provided for connecting the condensers in various combinations to vary the capacity. Mechanism for adjusting and pushing out the workpiece comprises a tube 143 axially adjustable in a clamp 144 and carrying a magnetic core 97 of radial laminations which is located at the'end of the workpiece to adjust the magnetic flux through the end of the workpiece. The core is cooled by a water circulating coil 211. The push-out rod 146, which is water-cooled internally, is moved axially by a bell crank lever 154 operated by a fluid-actuated piston 157 supplied by a pedal-operated pressure cylinder of the automobile brake type. The workpiece is inserted through a mouthpiece 96 having spaced guide teeth 185 which also remove, scale on withdrawing the workpiece. The mouthpiece is provided with a cover 52 normally spring-biassed to the open position. The pivot 190 projects into a control box where it actuates switches in the power supply circuit, and the cover is latched in its closed position by a solenoid-operated bolt. A water-cooling system is described, Fig. 12 (not shown), provided with control and signal devices, whereby water is supplied to coil 40, worksupporting rails 76, push-rod 146, iron core 97, condenser banks 56, and any necessary transformers. The cooling water supply is turned on, and its flow is controlled by thermostatic and pressure switches. A bar to be treated is placed within the coil 40 and the resulting backward movement of the push rod 146 closes the loading switch, and closure of the cover 52 permits the coil 40 to be energised when a rotary timing device controlling a number of machines allows the cycle to commence. After a predetermined time heating is cut off, cover 52 is released, and the workpiece may be removed by actuating the push rod 146. Signal lamps are provided to indicate correct operation of the various controls, and safety arrangements come into operation in the event of failure of power or water supply, which require that the machine be unloaded and reloaded before it can be restarted. Specification 560,837 is referred to.