The Story in a Steel Rail
A Blast Furnace.
Molten iron is brought from the blast furnaces to the open-hearth furnaces, and dumped into a receptacle called a mixer, the capacity of which ranges from 400 tons to 1000 tons, depending upon the number of furnaces to be served.
One-thousand-ton Mixer.
Pictures in this story by courtesy of Bethlehem Steel Co.
INSIDE OF OPEN HEARTH FURNACE
Charging Side of an Open-hearth Furnace.
An open-hearth furnace consists of a long, shallow hearth, suitably enclosed in fire-brick, and bound together with steel binding. The furnace is heated by burning gas and air, which have previously been preheated, so that a temperature is obtained in the furnace ranging from 2900 to 3050 degrees Fahrenheit.
Pouring Side of an Open-Hearth Furnace.
The open-hearth process consists of the purification of iron by oxidizing out the impurities and burning out the carbon of the iron until a tough and ductile steel is produced, which can be made of any desired composition by the addition of the necessary quantities of alloys just previous to tapping and pouring. The impurities in the iron are oxidized by the slag lying on top of the metal, and the burning out of the carbon, which is a very slow operation, is hastened by the addition of iron ore, the oxygen of which combines with the carbon of the iron and passes off is a gas going up the stack.
When an open-hearth furnace is ready for a charge, a variable amount of scrap, say 30 per cent of the total weight of material used for the heat, is charged into the furnace. With this scrap is charged sufficient lime or limestone to make the slag, as well as some iron ore to assist in reducing the carbon of the iron. In about two or three hours the required amount of molten iron is brought from the mixer in ladles, and poured into the furnace on top of the scrap, lime and ore.
MOLTEN STEEL BEING POURED LIKE WATER
Molten Steel Being Poured Into Ladle.
When the scrap has all been melted, a test is taken to determine the amount of carbon remaining in the bath. Iron ore is added from time to time until the carbon in the bath has been reduced to the desired point, and the metal is sufficiently hot to pour. At this point “recarburizers” (consisting of Ferro-Manganese, Ferro-Silicon, and pig-iron, or coal) are added to get the required composition. The tap hole at the back of the furnace is opened, and the steel is allowed to run out into a ladle, the slag coming last and forming a blanket over the steel in the ladle.
Crane Carrying Ingot and Soaking Pit Furnaces.
The ladle is picked up by an electric crane and carried over cast-iron moulds, which are set on cars, the steel being poured into the moulds, resulting in steel ingots. A sufficient amount of time is allowed for the steel to become chilled or set, when the cars are pushed under an electric stripper, where the moulds are removed from the ingots. After the ingots leave the stripper they are taken to the scales and weighed, and after weighing are put into the soaking pits. The pits get their name from the part they play in the heating of the steel for rolling. When the steel ingot is stripped the outside of the ingot is cool enough to hold the inside, which is still in a liquid state, and the steel is put into the soaking pits to allow the inside to settle into a solid mass, after which the ingot is reheated for rolling. The length of time in the soaking pits depends upon the size of the ingot, as the larger the ingot, the greater length of time is required to set.
GETTING READY TO MAKE A RAIL
When the steel is ready for rolling it is taken from the pits by overhead electric cranes, and placed into a dump buggy at the end of a roller line, which leads to the blooming mill. The dump buggy derives its name from the fact that when the ingot is placed into same in an upright position, the buggy, in order to place the ingot into a horizontal position on the roller line, dumps over, in the same way as if one were to rock too far forward in a rocking-chair, the dump buggy operating on the same principle.
Blooming Mill and Engine.
The ingot travels down the movable-roller line to the blooming-mill rolls, which roll it down from a piece 19 inches by 23 inches to what is known as an 8 inch by 8 inch bloom, which is the size usually used in the manufacture of rails. The blooming mill derives its name from the fact that after an ingot is rolled in same it is no longer called an ingot, but a bloom.
After leaving the blooming mill the bloom travels along another roller line to the shears, where it is cut into two or three pieces, the number of pieces depending on the size of the rail which is to be rolled. The blooms are then lifted over the roller line at the shears by a transfer crane, and placed on a traveling roller line which connects with the rear of the reheating furnace. This furnace is about 35 feet long, and is so constructed that when the bloom is pushed in at the rear of the furnace, another bloom drops from the front or discharge end of the furnace.
THE INGOT BECOMES A RAIL
The Ingot Becomes a Rail.
The bloom dropping out, being sufficiently hot to roll into rails, travels along another roller line to the roughing or first set of rolls. Here the bloom is given five passes in the rolls, and is then transferred to the strand or second set of rolls, where it receives five additional passes; after this operation it is transferred to the finishing or third set of rolls, in which it is given one pass. The bloom has now been converted into a rail, and the rail travels on another roller line to the hot saw, where it is cut into 33-foot lengths, this being the standard length in this country for all rails. The rails when hot are cut by the hot saw to lengths of about 33 feet 6¹⁄₂ inches, the allowance of inches being made for shrinkage in cooling. It is difficult to believe that steel shrinks to this extent, but this is a fact, and while the rails are cooling on the hotbeds they have the appearance of being animated, as they move first one way and then the other. After the rails are on the hotbed a sufficient length of time to cool, they are taken from the hotbed and placed on a traveling roller line, which takes them to an endless chain conveyor. The statement that rails are put on hotbeds for cooling seems paradoxical, but the hotbeds are so called because the rails are placed on them while hot, and are left there until they have cooled.
The endless-chain conveyor places the rails on another bed, from which they are picked up by an electric crane and distributed to the straightening presses, where all burrs (which have been caused by the hot-sawing operation) are removed before the rails are straightened. After straightening they are transferred to drill presses, where they have holes drilled into them for the accommodation of the splice bar, after which they are placed on the loading docks.
After being carefully examined by the railroad company’s inspectors they are picked up from the loading docks by electric magnets attached to a crane, and are placed in cars ready for shipment.