GB545074A - Improvements in apparatus for loading sheath wire electric heating units - Google Patents

Abstract

545,074. Electric heating elements. BRITISH THOMSON-HOUSTON CO., Ltd. July 21, 1941, No. 9196. Convention date, July 20, 1940. [Class 39 (iii)] Electric heating elements of the kind in which a resistance wire is embedded in powdered refractory material in a tubular sheath as described in Specifications 144,767 and 198,932, [both in Class 39 (iii)], are loaded with the insulating material while the sheath is rotated and intermittent blows imparted to it. The sheaths 11, containing the resistance held in a central position by temporary end caps, are arranged in upright positions'in a frame 15 and are provided with rotatably mounted heads 30, each having a hollow shaft 31 provided with ball bearings. The shaft is surmounted by a hopper 90 containing the powdered insulation. The sheath 11 is supported at intervals by transverse beams 43 carrying plates 47 with recesses in which the sheath is held by pivoted plates 49. The heads 30 are rotated as the sheaths are filled, by an electric motor 61 through toothed gearing 86 at about 20-25 revs. per minute. Blows are applied to the sheath at intervals along its length by vibrating hammers 101 pivoted at 102 and having springs 106 secured to the hammer and to a pin 112 on a plate 113 which is reciprocated so that the spring axis passes across the pivot 102 and a snap-acting blow is imparted by the hammer. Movement of the plate 113 is effected by an eccentric. device carried by the shaft 118 which is driven by the motor. The combined rotation and vibration of the sheaths retains the conductor in a central position and compacts the insulation. When filled, the sheaths are withdrawn and their diameter reduced by swaging. The ends of the sheaths are then severed to remove the portions which secure the temporary end caps.