Straightening


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Straightening

 

in metalworking, the elimination or reduction of unnecessary curvatures in metal items by the application of external forces. Straightening is used in the production of sheets, tubes, rails, beams, and other milled items. It is also used, although less frequently, in metal consumption, for example, by forges and metal structures shops.

Distinctions are made between press straightening (batch straightening) on straightening presses, parallel-roll straightening (continuous straightening) on straightening machines, and rotary straightening by untwisting and stretching on rotary straightening machines.

In press straightening, the item to be straightened is placed on two supports and force applied to the uneven surface causes elastoplastic deflection. Major disadvantages are the low precision of the straightening operation and the significant residual stress.

In parallel-roll straightening, the item moves in an axial direction and undergoes repeated elastoplastic deflection. The ovality of cross sections of bodies of revolution is eliminated at the same time by the spiral motion.

Stretch straightening, a type of rotary straightening, is used for thin sheets and bands, which may be elongated during the straightening process by 1.5–2.5 percent. Twisted tubes with cross sections that are not rounded are straightened by elastoplastic revolving-arbor straightening, which is sometimes combined with stretch straightening.

R. M. GOLUBCHIK


Straightening

 

(1) A process performed on rolled stock, wire, long forgings, stampings, castings, and machined parts to eliminate distortions and warpage that occur as a result of imperfections in manufacturing methods, operational overloads, or other factors. Straightening is usually done on cold stock by means of plastic deformation.

(2) In railroading, the aligning of track that has been displaced to either one or the other side by the action of rolling stock upon both rails of the track. The aligning is necessary to provide smooth travel for trains.

References in classic literature ?
Daylight, dis tam you mek one beeg meestake," French Louis said, straightening up and stepping down from the chairs.
That story was perfectly grand," she announced, straightening up from the wash-tub with a tired sigh and wiping the sweat from her forehead with a red, steamy hand; "but it makes me sad.
That claw is a goner," one of the station baggage-men said, straightening up from an examination of Michael through the bars.
he cried, straightening up and turning around on the dog.
When he finally gained his feet, another minute or so was consumed in straightening up, so that he could stand erect as a man should stand.
I had just finished, and was straightening up, when something floating around a bend above me caught my eye.
I took a step, and lo, away it scud with an elastic spring over the snow-crust, straightening its body and its limbs into graceful length, and soon put the forest between me and itself -- the wild free venison, asserting its vigor and the dignity of Nature.
He rose up straightening himself as though he were a hinged figure.
And just as Teeka sprang for the lower limb of a great tree, and Sheeta rose behind her in a long, sinuous leap, the coils of the ape-boy's grass rope shot swiftly through the air, straightening into a long thin line as the open noose hovered for an instant above the savage head and the snarling jaws.
He rose from his knees, and walked slowly across to the mantelpiece, where he stood abstractedly fingering the ornaments, and straightening them--a trick of his when he was agitated.
Yes," he said, straightening himself; "but we'd been talking it over at the office.
Watch out for squalls, is all I can say to you," was Louis's warning, given during a spare half-hour on deck while Wolf Larsen was engaged in straightening out a row among the hunters.