剪切刀片
底刃

Shear \Shear\, n. [AS. sceara. See {Shear}, v. t.]
1. A pair of shears; -- now always used in the plural, but
formerly also in the singular. See {Shears}.

On his head came razor none, nor shear. --Chaucer.

Short of the wool, and naked from the shear.
--Dryden.

2. A shearing; -- used in designating the age of sheep.

After the second shearing, he is a two-shear ram; .
. . at the expiration of another year, he is a
three-shear ram; the name always taking its date
from the time of shearing. --Youatt.

3. (Engin.) An action, resulting from applied forces, which
tends to cause two contiguous parts of a body to slide
relatively to each other in a direction parallel to their
plane of contact; -- also called {shearing stress}, and
{tangential stress}.

4. (Mech.) A strain, or change of shape, of an elastic body,
consisting of an extension in one direction, an equal
compression in a perpendicular direction, with an
unchanged magnitude in the third direction.

{Shear blade}, one of the blades of shears or a shearing
machine.

{Shear hulk}. See under {Hulk}.

{Shear steel}, a steel suitable for shears, scythes, and
other cutting instruments, prepared from fagots of
blistered steel by repeated heating, rolling, and tilting,
to increase its malleability and fineness of texture.