Rolling

(′rōl·iŋ)

(mechanics) Motion of a body across a surface combined with rotational motion of the body so that the point on the body in contact with the surface is instantaneously at rest.
(metallurgy) Reducing or changing the cross-sectional area of a workpiece by the compressive forces exerted by rotating rolls. Also known as metal rolling.
(naval architecture) The oscillating motion of a vessel from side to side due to ground swell, heavy sea, or other causes.

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Reducing or changing the cross-sectional area of a workpiece by the compressive forces exerted by rotating rolls. The original material fed into the rolls is usually an ingot from a foundry. The largest product in hot rolling is called a bloom; by successive hot- and then cold-rolling operations the bloom is reduced to a billet, slab, plate, sheet, strip, and foil, in decreasing order of thickness and size. The initial breakdown of the ingot by rolling changes the coarse-grained, brittle, and porous structure into a wrought structure with greater ductility and finer grain size.

A schematic presentation of the rolling process, in which the thickness of the metal is reduced as it passes through the rolls, is shown in illus. a. The speed at which the metal moves during rolling changes, as shown in illus. b, to keep the volume rate of flow constant throughout the roll gap. Hence, as the thickness decreases, the velocity increases; however, the surface speed of a point on the roll is constant, and there is therefore relative sliding between the roll and the strip. The normal pressure distribution on the roll and hence on the strip is of the form shown in illus. c. Because of its particular shape this pressure distribution is known as the friction hill.

The rolling process, (a) Direction of friction forces in the roll gap. (b) Velocity distribution, (c) Normal pressure acting on the strip in the roll gap. V_i = initial velocity, V_f = final velocity, V_roll = velocity during rolling operation.

A great variety of roll arrangements and equipment are used in rolling. The proper reduction per pass in rolling depends on the type of material and other factors; for soft, nonferrous metals, reductions are usually high, while for high-strength alloys they are small. Requirements for roll materials are mainly strength and resistance to wear. Common roll materials are cast iron, cast steel, and forged steel.

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The use of heavy metal or stone rollers on terrazzo topping to extract excess matrix.

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IN BRIEF: n. - Propelling something on wheels; A deep prolonged sound (as of thunder or large bells) adj. - Moving in surges and billows.

The gods had condemned Sisyphus to ceaselessly rolling a rock to the top of a mountain, whence the stone would fall back of its own weight — Albert Camus

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Involuntary rolling in animals; an important sign of abdominal pain or of disease of the vestibular apparatus. In the latter it is accompanied by persistent head rotation. Passive rolling is a therapeutic manipulation for the correction of torsion of the uterus in mares and cows. The animal is cast, laid on its back and swung sharply from side to side, sometimes with one hand in the rectum attempting to retard any movement of the fetus. The objective is to rotate the dam's body around an immobilized fetus and uterus.

• r. average — see moving average.
• r. disease — a nervous system disease of mice caused by Mycoplasma neurolyticum.
• r. mean — see moving average.
• r. skin syndrome — see idiopathic hyperesthesia syndrome.

For a list of words related to rolling, see:

• Cinematography Tools and Techniques - rolling: (adj) indication that cameras are shooting scene

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