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Encyclopedia Britannica - Main :: RHY-RON |
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ROLLINAT, MAURICE (1853-1903) , French poet, was born at Chateauroux in 1853. His father represented Indre in the National Assembly of 1848, and was a friend of George Sand, whose influence is very marked in young
Rollinat
ROLLING-MILL, a term which includes several types of machines used for producing the sectional forms (fig. I) in which wrought iron and steel are required for the use of boiler-makers, platers and bridge-builders, and for constructional work
design , the growth in the use of steel has revolutionized the practice, chiefly on account of the more massive dimensions in which steel sections are rolled. Iron sections are relatively small, and many are produced by piling, i.e. by building up with small portions of malleable puddled metal. There is no limit in reason to the dimensions in which steel sections can be rolled, and they are never piled, however large, but always rolled from solid cast ingots.When steel ingots are rolled into sectional forms the reduction in transverse dimensions is very great
work
It might be thought, since steel is always cast previously to rolling, that it might be cast at once into the sectional forms required. But sound results could not be obtained in this way, because the gases occluded in the metal form blow-holes which are sources of weakness. The material itself, even in the solid portions, is not homogeneous. By removing the head of the ingot where the blow-holes chiefly congregate and rolling the remainder at a white or red heat, the metal is improved by consolidation, and by the work done upon it. To this practice there is no exception. Rolling-mills are known as " two-high," or " three-high," according as two or three rolls are mounted one over the other .Ye 37 as J9 I, 2, Flats. 3, Flat with bevelled edges. 4, 5, Flats with rounded edges. 6, Bulb bar. 7, Wedge bar. 8, Scree or grate bar. 9, Square. to, Triangular. it, Hexagonal. 12, Round. 13, Oval. 14, Hollow half-round. 15, Half-round. 16, Convex. 17, Square-edged convex. 18, Vee. 19, O.G. 20, Angle iron. 21, Square root, or square throat angle. 22, Round-backed angle. 23, Unequal-sided angle. 24, Acute angle. 25, Obtuse angle. 26, Bulb angle. 27, Tee. 28, Bulb tee. 29, 30, Beams or joists, or girders, or H-irons. 31, Channel. 32, Zed. 33, Cruciform section. 34, Pillar section. 35, Troughing. 36, 37, 38, Rail-way rail. 39, Tramway rail. 40, Heavy crane rail. (figs. 2 and 3). In the two-high type the two rolls revolve in opposite directions, so that an ingot, slab or bloom presented to the entering side is drawn
gradual . To regulate the amount the top roll is set down bodily by means of screws pressing on its bearings which slide in the end supports (housings). In the case of plate-rolls, which are plain cylinders, this setting down must be equal at each end. The mass of the top roll is balanced, to avoid shock when a plate is entering. The rolls are made of cast iron, and are either grain rolls or chilled rolls. The first are formed from a tough strong grade of iron, the quality which is used for all the roughing down and general work. The second are made of a highly mottled iron, cast against a cold mould (chill) of cast iron, by which a steely surface is obtained. These are used for fine finishing, or for imparting a polished surface to a section already nearly reduced to size in grain rolls. In later heavier practice, rolls of cast steel and forged steel are becoming common. They are more costly than iron, but more durable and much lighter for equal strength. They are essential in armour plate rolls. The length of rolls should not exceed about four times their diameter , for otherwise they are liable to spring and produce plates thicker at the centre than towards the edges.From this elementary design several types are derived. In the two-high mill it is clear that if the direction of the rotation of the rolls is always the same, then the plate being rolled must be taken back after each " pass " to the front of the rolls. Hence there is one " lost pass " for every reduction in thickness. This is the case in the " pull-over " mill, nearly obsolete. In the two-high reversing mill, introduced to avoid this " lost pass," as soon as a plate has gone through, the direction of rotation of the rolls is reversed, and the plate is rolled again on the backward journey, so avoiding the lost7 2 w -`00 AIM /ORNACf ao/LER COOL/NC BANK' 3N1AR3 (1 0 End of Article: ROLLINAT, MAURICE (1853-1903) If you wish, you can link directly to this article.
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