1016 



IRON 



Staffordshire establishments. Those roughing cylinders are generally 7 foot long, 

 including the trunnions, or 5 foot between the bearers, and 18 inches diameter ; :m<l 

 weigh in the whole from 4 to 4 tons. They contain from 5 to 7 grooves, commonly 

 of an elliptical form, one smaller than another in regular progression, as is seen in fig. 

 1280. The small axis of each ellipse, as formed by the union of the upper and under 

 grooves, is always placed in the vortical direction, and is equal to the great axis, or 



horizontal axis of the succeeding groove ; so 



1280 that in transferring the bar from one groove 



to another, it must receive a quarter of a 

 revolution, whereby the iron gets elongated 

 in every direction. Sometimes the roughing 

 rolls serve as preparatory cylinders, in which 

 case they bear towards one extremity rect- 

 angular grooves, as the figure exhibits. 

 Several of these large grooves are bestudded 

 with small asperities analogous to the teeth 

 of files, for biting the lump of iron, and pro- 

 venting its sliding. On a level with the 

 under side of the grooves of the lower cylin- 

 der, there is a plate of cast iron with notches 

 in its edge adapted to the grooves. This 

 piece, called the apron, rests on iron rods, 

 and serves to support the balls and bars 

 exposed to the action of the rollers, and to 

 receive the fragments of ill-welded metal, 

 which fall off during the drawing. The 

 Jiousing frames in which the rollers are 

 supported and revolve, are made of great 

 strength. Their height is 5 feet ; their 

 thickness is 1 foot in the side perpen- 

 dicular to the axis of the cylinders, and 10 

 inches in the other. Each pair of bearers is 

 connected at their upper ends by two iron 

 rods, on which the workmen rest their tongs 

 or pincers for passing the lump or bar from 

 one side of the cylinders to the other. 



The cods or bushes are each composed of 

 two pieces ; the one of hard brass, which pre- 

 sents a cylindrical notch, is framed into the 

 other which is made of cast iron, as is clearly 

 seen in fig. 1280. 



The iron bar delivered from the square 

 grooves, is cut by the shears into short 

 lengths, which are collected in a bundle in 

 order to be welded together. When this 

 bundle of bars has become hot enough in the 

 furnace, it is conveyed to the rollers, which 

 differ in their arrangement according as they 

 are meant to draw iron from a large or small 

 piece. The first, fig. 1 280, possess both ellipti- 

 cal and rectangular grooves; are 1 foot in 

 diameter and 3 feet long between the bearers. 

 The bar is not finished under these cylinders, 

 but is transferred to another pair, whose 

 grooves have the dimensions proper for the 

 bar, with a round, triangular, rectangular, or 

 fillet form. The triangular grooves made use 

 of for square iron have for their profile an 

 isosceles triangle slightly obtuse, so that the 

 space loft by the two grooves together may bo 

 a rhombus, differing little from a square, and 

 whose smaller diagonal is vertical. When the bar is to be passed successively 

 through several grooves of this kind, the larger or horizontal diagonal of each 

 following groove is made equal to the smaller or upright of the preceding one, 

 whereby the iron must be turned one fourth round at each successive draught, and 

 thus receive pressure in opposite directions. Indeed, the bar is often turned in 

 succession through tho triangular and rectangular grooves, that its fibres may be more 



