Fig. 23 shows the general type of rolls used for wrought-iron piles. This machine is very simple, and consists essentially of three chilled cast-iron rolls A, B, C, mounted in a frame DD (called the housings) so that the axes of the rolls are horizontal and one above another. Rolls A and C are driven by a large engine through the connecting shafts G and H, and the middle roll is free. The bearings of the lower roll are fixed in the housings of the machine, the bearings of the middle roll are free to raise or lower, and those of the upper roll are raised or lowered by long screw rods worked simultaneously by the gearing on top of the machine. In this way the space between the rolls is adjusted readily by the operator to suit the thickness to which the iron is to be reduced as it passes through.

The mass of iron which passes back and forth through these rolls is handled by a roller table on each side of the machine. The roller table on one side is shown in the foreground. Its rollers are connected by gearing (not shown) so that all rollers may be made to revolve in either direction simultaneously. As the table now rests, it shows a plate L which has just come through between the middle and lower rolls. In order to run this plate back between the middle and upper rolls, the end of the table is lifted by hydraulic power. The table end having been lifted to the required height, its rollers are reversed and the plate is conveyed into the rolls of the machine.

Fig. 23. - Rolls for Making Wrought Iron Plates.

Roughing and finishing rolls are of similar construction, but the former is a heavier machine than the latter. Most the shaping is done in the roughing rolls to save the smoother surface of the finishing rolls for the more careful work they have to do in finishing plates to a smooth surface and to uniform thickness.

A machine for rolling bars or rods has passes in the rolls similar to those in the puddle rolls in Fig. 21.

When material has been rolled to the shape and size required, it is carried by the roller table to another part of the shop where it is inspected for defects, and is then cut by the power shears to the required dimensions.

IV. The Manufacture of Steel.