Whether it is to be sold in intermediate shapes or further rolled down into a finished product, all ingots have to be “cogged” or broken down into intermediate-sized slabs, blooms or billets, for an ingot contains altogether too much steel for any single plate, rail, rod, or other finished product.
The cogging or first rolling is accomplished in one of the three types of rolls already described but now more generally in the reversing mill.
Ingot Coming Out of the “Soaking Pit”
When the tongs of the big overhead crane have lifted the white-hot ingot out of the soaking pit it is run back and forth through the rolls which are forced nearer and nearer together by the “screw-down” man so that the piece continually becomes thinner and much longer with each pass. Tables made up of small rollers geared together receive the long piece as it emerges from the rolls. After each pass they bring the piece back to the rolls which are now turning in the opposite direction. The table on the other side repeats the process, the piece being regularly turned on edge or slid from one side of the rolls to the other by steel guides which can be raised up between the rollers of the tables where desired. The direction of these as well as of the rolls themselves is controlled through levers by two or three men standing at one side of the mill.
Reversing after each pass, with the big ingot apparently turning and sliding itself into the most advantageous position for the next entry, the big engine, mill and roll-train seem almost human.
Ingot in the Rolls
The Rolling of Steel Plates
It is manifestly impossible in the space at disposal to give in much detail the rolling of many of the better known products. Fortunately it is not necessary, for after description of the making of plate, pipe and tube, and of rod and wire, the rolling of other forms such as rails, bars, and the structural shapes, I beams, channels, angles, Z bars, etc., can well be imagined.