GB519325A - Improvements in or relating to heating furnaces - Google Patents

Abstract

519,325. Metal-heating furnaces. CURRAN BROS., Ltd., and CURRAN, J. Sept. 20, 1938, No. 27404. [Class 51 (ii)] [Also in Group XXXV] A furnace for heating metals such as cartridge cases comprises a heating chamber 1, preheating chamber 7 and cooling chamber 8 with means for circulating gas through the chambers 7 and 8 which are connected by flues 9, 10. Doors 3 and 4 are provided at the ends of the chamber 1 and doors 5, 6 at the outer ends of the chambers 7, 8. The preheating chamber 7 is divided by a door 5a into compartments 12, 13. Electric heating elements. 17, 16 are provided in the chamber 1 and compartment 12. The circulation of gases is effected by a fan 11. The stream of gas passing from the cooling chamber 8 to the preheating chamber 7 is divided between the compartments 12, 13 by dampers 15, 18 under the control of thermostats arranged in the chamber 8 and compartment 12. In the control circuit shown in Fig. 2, current from the mains 27, 28 passes through contacts 26 to a thermostat C in the compartment 12 and a solenoid or motor 24 for operating the dampers 15, 18. The dampers are closed when the contacts 26 are in the off position. When the contacts 26 are closed current also passes through leads 29, 30 to the fan circuit. Current also passes from the mains 27, 28 through contacts 25 to the heating elements 16 in the compartment 12. These contacts 25 are controlled by a circuit including contacts 32 and thermostats A, B in the chamber 8 and compartment 12 respectively. When the temperature in the compartment 12 rises above a predetermined value contacts 25 are opened, contacts 33 are closed and a circuit is closed to close the contacts 26 to start the fan 11. The thermostat C may then cause opening of the dampers 15, 18.