GB694153A - Electric oven for the burning of ceramic articles - Google Patents

Abstract

694,153. Dental furnaces. NEOLIZA ZAHNFABRIK AKT.-GES. Dec. 5, 1951 [Dec. 8, 1950], No. 28502/51. Class 51(ii) [Also in Group XI] An electric oven for baking ceramic articles e.g. artificial teeth comprises a heating chamber 10 divided into several compartments by horizontal plates 13 carrying heating resistances, the chamber being enclosed by an airtight double casing 4 having an internal lining of loosely stacked blocks 9 of refractory material enclosing the heating chamber, a partial vacuum being maintained in the heating chamber 10 and in the casing 4 during use. The casing 4 comprises a welded annular cylinder welded to a rear plate and having at the front a circular iron door 1 with a packing 3 to bear on the front of the casing. The shaped ceramic or clay bricks 9 may be numbered to aid ready assembly. Heating resistance wires (see Group XI) are mounted in slotted circular recesses in steatite plates 13, which are slid at their edges into grooves 12 in vertical steatite side plates 11. The blocks 9 and side plates 11 are recessed or apertured for the passage of connecting wires to the supply wires 21 or for the insertion of pyrometers 22 or thermostats. The top plate 14 of the heating chamber carries no heating resistances. The casing 4 and heating chamber are connected through valved pipes 31, 32, 33 to a vacuum pump 29, and filters 36 such as wire gauze or glass wool are placed at the inner ends of the pipes, to prevent entry of solid particles when air is admitted to the oven. The front of the oven is heat insulated by removable bricks 19, which are apertured at 27 to allow passage of a bolt holding them together: