Page:The New International Encyclopædia 1st ed. v. 17.djvu/254

* ROLLING MILL. 230 ROLLO. The construction of a set or stand of rolling- mill rolls is iiuite simple. The rolls are made of chilled cast iron turned to cjliudrical form and are journaled at their ends in a strong frame or housing of cast iron. It is essential above all things that this housing shall be strong and rigid and so constructed that the rolls can be taken out and repaired or changed quickly and easily. Sometimes the rolls are so fixed and ad- justed in the housing that their distance apart can be quickly increased or decreased while they are in place, and at other times they are placed in the housing in a definite fixed position which cannot be changed during operation. The hous- ing is founded on a structure of masonry set be- low the mill floor. In finishing mills for light work the engine is sometimes connected only to one roll, the other roll being turncjd by the fric- tion of the metal as it passes between the two. For heavier work both rolls are positively ope- rated direct from the engine. The simplest form of roll is a plain cylindrical one for rolling plates. For rolling nearly all other forms of rolled shapes the metal has to be confined laterally, and to accomplish this the rolls are provided with grooves varying in shape according to the finished form it is desired to secure. C4enerally each set of rolls has two or more grooves, each set of which approaches closer to the form of the fin- ished section than the set of grooves preceding it, and the metal is passed through these grooves in order. Commonly also several sets of rolls are employed, each set of which brings the piece closer to its final form than the set preceding. In cer- tain kinds of work the several stands of rolls are so arranged that the rolling process is continu- ovis. For example, in rolling round rods for wire- drawing, the billet from the blooming mill passes through one groove, then is looped and returned through another, and so on until the final groove of the final stand of rolls produces the finished rod of small diameter. In the universal mill largely used in rolling plates the metal is com- pressed lateral!}' bv means of a pair of vertical rolls set close behind the horizontal rolls. There are also special forms of mills for rolling wheel tires, hoops, and other special shapes. The mills of the Pencoyd Iron Works, at Pen- coj'd. Pa., may be described as t_ypical of modern practice. The steel ingots as produced by the steel plant (see Iron and Steel) are delivered by electric traveling cranes and cars to the pit furnaces of the blooming mill, where they are subjected to the first rolling process to reduce them to blooms and billets. The blooming mill is a two-high reversing mill, and the ingots are delivered to it and manipulated between the dif- ferent passes by 'tables' operated by hydraulic power from a central station. These tables raise, turn, and shift the piece transversely or longi- tudinally as desired. This mill is fed with hot ingots by four vertical pit furnaces of the regenerative type fired with producer gas, and in tvirn it supplies three finishing mills and an axle forge. The principal part of the product goes to the beam mill, which is supplied with hot blooms. The beam mill is placed in the line of the delivery of the blooming mill and is served with three regenerative heating furnaces for re- storing full working temperature to the blooms on their passage from the blooming mill. The billets are charged into and withdrawn from these furnaces by machinery. The beam mill consists of two distinct mills, one a roughing mill for roughly forujing the beam and the other a finishing mill. The roughing mill is a two-high reversing mill and tlie finishing mill is of the three-high type. The roughing mill is served with reversing tables and hydraulic manipulators, while the finishing mill has traveling tables which also have a lifting movement. The product of the finishing mill is delivered by live rollers to saws and shears, thence to cooling beds, straight- ening machines and shears, and finally to the storage yards. From the time the ingot leaves the steel mill until the finished beam is in the storage yard it is handled wholly by maehinery. The foregoing is a typical example of the per- fection of modern rolling-mill practice in produc- ing structural iron and steel. In rolling rails the billet from the blooming mill passes directly to a three-high rail mill. Steel Shapes. The shapes turned out by the modern rolling mill are limited only by the fact that thoy must in each case be of uniform section throughout the length of the piece, and the fact that the roller grooves cannot be wider at the bottom than the top. The more common stand- ard shapes are plates, flats, squares, rounds, half- rounds, angles, channels, I beams, Z bars, T iron. 1 Beam. r^. ^ J..-J Tee Bar. Channel. ti^mw I Angle. Bulb Beam. ZBar. BTRrCTURAL STEEL SHAPES. trough shapes, rails, and bulb angles. In struc- tural work these direct shapes are riveted to- gether to form the various compotmd shapes used for columns for buildings, bridge members, etc. The literature on rolling-mill construction, equipment, and practice exists almost wholly in the shape of special articles in the Proceedings of the various engineering societies and in the columns of the engineering papers. ROL'LO, Hrolf, Eolf, or Rou (real name Heolfe, known as the Ganger, or Walker). A Xorse chieftain of whose early histor.v nothing definite is kno«Ti. He seems to have effected ex- tensive conquests in Xorthwestern France, and by the Peace of Clair-en-Epte, about 912. he was granted by King Charles the Simple of France the possession of Rouen and the adjacent terri- tory which he already held. This was the origin of the Duchy of Normandy. Rollo was baptized with many of his companions. He divided his lands among his followers, framed laws for his people, and made great donations to the Church. He was a faithful ally of Charles the Simple. By successful wars he graduall.v extended his possessions. About 927 he associated his son William Longsword with himself as ruler. He