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Steel MakingAnnealing Of Rifle Components At Springfield ArmoryIn general, all forgings of the components of the arms manufa... Heat-treating Department The heat-treating department occupies an L-shaped building. ... Knowing What Takes Place How are we to know if we have given a piece of steel the ver... Classifications Of Steel Among makers and sellers, carbon tool-steels are classed by g... Rate Of Cooling At the option of the manufacturer, the above treatment of gea... Quenching The Work In some operations case-hardened work is quenched from the bo... Tensile Properties Strength of a metal is usually expressed in the number of pou... Chrome-nickel Steel Forging heat of chrome-nickel steel depends very largely on ... The Theory Of Tempering Steel that has been hardened is generally harder and more br... Effect Of Different Carburizing Material [Illustrations: FIGS. 33 to 37.] Each of these different p... Placing Of Pyrometers When installing a pyrometer, care should be taken that it re... The Quenching Tank The quenching tank is an important feature of apparatus in c... Carburizing By Gas The process of carburizing by gas, briefly mentioned on page ... The Pyrometer And Its Use In the heat treatment of steel, it has become absolutely nece... Mushet And Bessemer That Mushet was "used" by Ebbw Vale against Bessemer is, perh... Temperature Recording And Regulation Each furnace is equipped with pyrometers, but the reading an... Effects Of Proper Annealing Proper annealing of low-carbon steels causes a complete solu... Care In Annealing Not only will benefits in machining be found by careful anne... Hardening High-speed Steel In forging use coke for fuel in the forge. Heat steel slowly ... Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer For extremely high temperature, the optical pyrometer is lar... |
Typical Oil-fired FurnacesCategory: FURNACES Several types of standard oil-fired furnaces are shown herewith. Figure 92 is a lead pot furnace, Fig. 93 is a vertical furnace with a center column. This column reduces the cubical contents to be heated and also supports the cover. A small tool furnace is shown in Fig. 94, which gives the construction and heat circulation. A larger furnace for high-speed steel is given in Fig. 95. The steel is supported above the heat, the lower flame passing beneath the support. For hardening broaches and long reamers and taps, the furnace shown in Fig. 96 is used. Twelve jets are used, these coming in radially to produce a whirling motion. Oil and gas furnaces may be divided into three types: the open heating chamber in which combustion takes place in the chamber and directly over the stock; the semimuffle heating chamber in which combustion takes place beneath the floor of the chamber from which the hot gases pass into the chamber through suitable openings; and the muffle heating chamber in which the heat entirely surrounds the chamber but does not enter it. The open furnace is used for forging, tool dressing and welding. The muffle furnace is used for hardening dies, taps, cutters and similar tools of either carbon or high-speed steel. The muffle furnace is for spring hardening, enameling, assaying and work where the gases of combustion may have an injurious effect on the material. Furnaces of these types of oil-burning furnaces are shown in Figs. 97, 98, and 99; these being made by the Gilbert & Barker Manufacturing Company. The first has an air curtain formed by jets from the large pipe just below the opening, to protect the operator from heat. Oil furnaces are also made for both high- and low-pressure air, each having its advocates. The same people also make gas-fired furnaces. Several types of furnaces for various purposes are illustrated in Fig. 100 and 101. The first is a gas-fired hardening furnace of the surface-combustion type. A large gas-fired annealing furnace of the Maxon system is shown in Fig. 101. This is large enough for a flat car to be run into as can be seen. It shows the arrangement of the burners, the track for the car and the way in which it fits into the furnace. These are from the designs of the Industrial Furnace Corporation. Before deciding upon the use of gas or oil, all sides of the problem should be considered. Gas is perhaps the nearest ideal but is as a rule more expensive. The tables compiled by the Gilbert & Barker Manufacturing Company and shown herewith, may help in deciding the question. TABLE 27.--SHOWING COMPARISON OF OIL FUEL WITH VARIOUS GASEOUS FUELS Heat units per thousand cubic feet Natural gas 1,000,000 Air gas (gas machine) 20 cp 815,500 Public illuminating gas, average 650,000 Water gas (from bituminous coal) 377,000 Water and producer gas, mixed 175,000 Producer gas 150,000 Since a gallon of fuel oil (7 lb.) contains 133,000 heat units, the following comparisons may evidently be made. At 5 cts. a gallon, the equivalent heat units in oil would equal: Per thousand cubic feet Natural gas at $0.375 Air gas, 20 cp at 0.307 Public illuminating gas, average at 0.244 Water gas (from bituminous coal) at 0.142 Water and producer gas, mixed at 0.065 Producer gas at 0.057 Comparing oil and coal is not always simple as it depends on the work to be done and the construction of the furnaces. The variation rises from 75 to 200 gal. of oil to a ton of coal. For forging and similar work it is probably safe to consider 100 gal. of oil as equivalent to a ton of coal. Then there is the saving of labor in handling both coal and ashes, the waiting for fires to come up, the banking of fires and the dirt and nuisance generally. The continuous operation possible with oil adds to the output. When comparing oil and gas it is generally considered that 4-1/2 gal. of fuel oil will give heat equivalent to 1,000 cu. ft. of coal gas. The pressure of oil and air used varies with the system installed. The low-pressure system maintains a pressure of about 8 oz. on the oil and draws in free air for combustion. Others use a pressure of several pounds, while gas burners use an average of perhaps 1-1/2 lb. of air to give best results. The weights and volumes of solid fuels are: Anthracite coal, 55 to 65 lb. per cubic foot or 34 to 41 cubic feet per ton; bituminous coal, 50 to 55 lb. per cubic foot or 41 to 45 cubic feet per ton; coke, 28 lb. per cubic foot or 80 cubic feet per ton--the ton being calculated as 2,240 lb. in each case. A novel carburizing furnace that is being used by a number of people, is built after the plan of a fireless cooker. The walls of the furnace are extra heavy, and the ports and flues are so arranged that when the load in the furnace and the furnace is thoroughly heated, the burners are shut off and all openings are tightly sealed. The carburization then goes on for several hours before the furnace is cooled below the effective carburizing range, securing an ideal diffusion of carbon between the case and the core of the steel being carburized. This is particularly adaptable where simple steel is used. Next: Protective Screens For Furnaces Previous: Air-hardening Steels
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