Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . d with heated air under a slight pressure, which is exertedaround a thermometer stem when the door is closed. The burner is controlled by the air valve A, and the gas valve^G. The connection with blower is to the drum, D, and gas isbrought to the gas valve, G. The burner distributes the heatevenly under the muffle and around it, so that the atmospherictemperature within the working space of the muffle is perfectlyeven throughout. , The work is placed upon a w
Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . d with heated air under a slight pressure, which is exertedaround a thermometer stem when the door is closed. The burner is controlled by the air valve A, and the gas valve^G. The connection with blower is to the drum, D, and gas isbrought to the gas valve, G. The burner distributes the heatevenly under the muffle and around it, so that the atmospherictemperature within the working space of the muffle is perfectlyeven throughout. , The work is placed upon a wire tray and evenly distributedover its surface, and is constantly subjected to the action of freshair heated to the proper degree. The tray containing the work rests upon the open grating 62 HARDENING, TEMPERING AND ANNEALING. shown in the cut, which is raised above the bottom of the muffle,and the heated air is forced through and around the work fromthe perforated heating chamber, thus coming in contact withfreshly heated air constantly. The operation is as follows: It will-require about 40 minutes to heat a furnace of this type. FIG. 33.—AIR TEMPERING OVEN. to the 600 deg. required for a blue temper. This temperaturebeing indicated by the thermometer, the work is inserted and thedoor closed. The thermometer will then show a decided decreasein temperature due to the absorption of the heat by the lapse of a certain time, determined by the weight of the HEATING STEEL GAS BLAST FURNACES. (^z charge, the temperature will commence to rise again, and whenit gets back to, say, 600 deg., where the thermometer stood whenthe work was inserted, the work is promptly removed. It should be remembered that the thermometer will not indicatethe precise temperature at which steel reaches a certain tempercolor under other conditions, but the temperature at which workwill reach the exact temper color desired being once noted, the
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Keywords: ., bookcentury1900, bookdecade1900, bookidhardeningtem, bookyear1903
