Z94.12.4 Metal Forming

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TEMPER BRITTLENESS. Brittleness that results when certain steels are held within, or are cooled slowly through a certain range of temperatures below the transformation range. The brittleness is revealed by notched-bar impact tests at room temperature or lower temperatures.

TEMPERING. A process of reheating quench-hardened or normalized steel to a temperature below the transformation range, and then cooling at any rate desired mainly to reduce brittleness.

TENSILE STRENGTH. The maximum tensile stress that a material is capable of withstanding without breaking under a gradually and uniformly applied load. Its value is obtained by dividing the maximum load observed during tensile straining by the specimen cross-sectional area before straining. Other terms that are commonly used are ultimate tensile strength, and less accurately, breaking strength.

THROAT (GAP) DEPTH. The distance from the slide centerline to the frame of a gap-frame press.

TIE RODS. Steel rods, threaded at both ends for nuts, used to prestress straight-side press frames. They are also used to reduce deflection in gap-frame presses, but require careful installation.

TOGGLE JOINT. A connecting mechanism consisting of two links freely pinned together at one end and connected by free pins to other press parts at their other or outer ends.

TONNAGE. (See CAPACITY, PRESS.)

TORSIONAL STRENGTH. The maximum stress that a metal can withstand before fracture when subjected to a torque or twisting force. Stress in torsion involves shearing stress, which is not uniformly distributed.

TOUGHNESS. As determined by static tests, toughness is considered to be the work per unit volume required to fracture a metal. It is equal to the total area under the stress-strain curve, represents the total energy-absorbing capacity, and includes both elastic and plastic deformation. Toughness in practice is more often considered to be resistance to shock or impact, which is a dynamic property.

TRIMMING. A secondary cutting or shearing operation on previously formed, drawn, or forged parts in which the surplus metal or irregular outline or edge is sheared off to form the desired shape and size.

TRIP (OR TRIPPING). Activation of the clutch to run the press.

TRIPPING MECHANISM. Any auxiliary mechanism, manually, mechanically, or automatically operated, which engages and disengages the clutch for starting and stopping the press.

TWIST. The tendency of material (strip) that is being sheared off to curve about a central longitudinal axis.

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