| 摘要 |
PURPOSE:To subject a steel material to gas cementaion in a highly precise manner under a less dangerous condition so as to obtain uniform quality by a method wherein CO2 and CO of an atmospheric gas in a heat treating furnace is analysed and introduction of an enrich gas is controlled so as to keep an equilibrium carbon concn. constant. CONSTITUTION:An inside of a heat treating furnace in which a steel material treating article W is kept under a hermetically sealed condition and evacuated by a vacuum pump and, thereafter, nitrogen gas is introduced thereinto from a pipe passage 2 to restore a pressure to a constant pressure. Subsequently, a hydrocarbon and an oxidizing gas are introduced from a pipe passage 3 to form an atmospheric gas with a predetermined equilibrium carbon concn. The resultant atmospheric gas is analysed by a CO analyser 6 and a CO2 analyser 11. By caluculation from the resultant CO amount analysed value, a temp. in the furnace measured by a thermocouple 7 and a desired carbon concn. on a surface of the treating article W set by a carbon concn. setting instrument 8, an operation apparatus 10 calculates an objective CO2 amount and the calculated value is applied to a CO2 controller 9 as a set value. The controller 9 adjusts a controll valve 4 by a deviation signal of the CO2 analysed value and an objective value to increase and decrease an amount of an enrich gas. |
