Forge furnaces

In the first or foundry furnace, the excess of autumn over winter months is eleven per cent. in the forge furnace equal to five per cent., and in the blast fifteen per cent. 

Slot furnaces are in general use throughout the steel industry to heat steel for forging and are usually fired with light oil. Because many such furnaces are located in small businesses, it is difficult to obtain an accurate estimate of their total energy use. The best approximation available is that about 0.2 quad is consumed in slot forge furnaces annually. 

In a batch forge furnace, the space above the load(s) was held at 2250 F, wall to wall. High-velocity stirring burners were fired between the 8 in. tall piers supporting the load(s). The burners were operated with fuel turndown only to minimize the concentration of triatomic molecules while inducing a high mass of inert gas from above the load. The wall-to-wall temperature drop under the product was very low—a maximum of 6°C (3.3°C). Chapter 8 discusses temperature uniformity in more detail. 

Preheating loads with waste gases has been widely practiced in the forging and hardening of tools.. . from the village blacksmith to slot forge furnaces where extra loads were placed in the slot for preheating. Their fuel efficiency may not have been so crude after all. Fuel was often scarce or dear. Necessity was the mother of invention. 

TABLE 6.3 Benefits of automatic furnace pressure controi—A case history. Batch forging furnace heating 5200 ib (2364 kg) of 3.9 in. (0.1 m) diameter steel parts to 2400 F (1316 C) with natural gas. Ceramic fiber walls 8" (0.2 m) thick. 

UNIFORMITY CONTROL IN FORGE FURNACES (for forging small steel pieces, see sec. 3.8.7)... 

If a flue poc carries heavy particulates and has ells (elbows) or horizontal sections where particles may be deposited, flues must be made even larger, and clean out doors must be provided, and used For some forge furnaces and for bolt heading furnaces, all the poc are purposely forced out the slot through which the stock is charged. 

Slot forge furnaces are wasteful of fuel and prone to uneven heating because of the tremendous heat loss through the slot. They must have movable flaps for easy opening to add or withdraw pieces, and operators must be convinced that they must close them promptly after every use. 

Robert A. Shannon has more than 50 years experience with engineering work. He has been North American Mfg. Co. s authority on steel reheat furnaces, soaking pits, and forging furnaces. He continues private consulting relative to his extensive experience with steel reheat, pelletizing, forging, heat treating, catenary furnaces, and industrial boilers. 

---