GB1299398A - Multi-chamber carburizing method and apparatus - Google Patents

Abstract

1299398 Carburizing furnaces HOLCROFT & CO 18 Aug 1970 [23 March 1970] 39694/70 Heading F4B Workpieces to be gas carburized are successively passed, from a charging vestibule 16 through radiant tube heated heating, carburizing and diffusion furnaces 18, 32 and 54 respectively, and then discharged into an oil quench tank 70, the baskets and trays (not shown) on which the workpieces are carried being recycled back to the charging vestibule after being reloaded with fresh workpieces. Motorized pushers pass double rows of the loaded trays into, through and out of the various furnaces over rails, e.g. 138, 140, Fig. 7. Single raisable refractory doors 72, 24 (see Fig. 4, not shown) close the outlet from the diffusion furnace and the inlet to the heating furnace, whilst double raisable refractory doors 36, Fig. 2, and 58 close the inlet and the outlet of the carburizing furnace 32. The oil quench tank 70 (see Fig. 6, not shown) is-divided by depending upper wall 80 into two intercommunicating oil filled chambers 74, 78, an elevator structure (208, Fig. 6) depositing the workpiece carrying trays into the oil bath in chamber 74, then transferring them to chamber 78 and finally raising them for discharge through aperture 82. Control means 96 synchronize the raising of the doors and the actuation of the motorized pushers and the elevator structure in the desired sequence. In operation, a neutral gas is fed into heating furnace 18 through end wall inlets (126, 128, Fig. 8, not shown) a carburizing gas comprising endothermic gas and hydrocarbon gas, is fed through inlets 144, 146, Fig. 1, into carburizing furnace 32 and a gas comprising endothermic gas and combustion products or air, is fed into diffusion furnace 54 through an end wall inlet (206, Fig. 9, not shown). Channels, e.g. 188, 187, Figs. 2 and 7 beneath the single and double doors allow the atmosphere gases to flow from the furnaces, whereby vent lines in vestibule 16 and chamber 74 may be used to remove the gases from the heating and diffusion furnaces. The gases from the carburizing furnace 32 may either be vented through lines 184, 189, Figs. 1 and 2, between the double doors 36, 58 together with some of the gases from the heating and diffusion furnaces respectively, or through vent lines 147, 149, Fig. 7, within the carburizing furnace in which case metal barrier gases are supplied through the lines 184, 189 between the double doors 36, 58 to prevent heating or diffusion furnaces gases entering the carburizing furnace, or they may be vented through line 189 between double doors 58, whilst endothermic gas is supplied through line 184 to the double door 36.