Power Forging and Methods Of Power Forging

Large machine parts cannot be forged by hand, since the comparatively light blow of a hand-or-sledge-hammer is unable to produce a great degree of deformation in the metal being forged. Moreover, hand forging is a lengthy process and requires repeated heating of the metal. This has led to the use of power hammers and presses in forging. Machines which work on forgings by blow are called hammers, while those working by pressure are called presses.

POWER HAMMERS :

All Power employ the same general principle of operation, a falling weight striking the blow, with the entire energy being absorbed by the work. Where further blows are necessary, the striking weight is raised for the succeeding blow. Some hammers employ only a gravity fall, the energy delivered on the work being the product of the weight of the hammer head and the distance of the fall. Other hammers increase the striking velocity of the hammer head by mechanical means.

The part of the hammer which serves as a rigid support during forging is called the anvil block. The anvil block of a forging hammer is built on a foundation separate from the frame so that the shock of the hammer blows will be cushioned by the foundation and will not be transmitted to the frames. The heavy falling part of the hammer is called the ram. The anvil block and the ram each one die called upper-die and lower-die respectively for squeezing the metal to be forged. In smith forging, the working surfaces of both the upper and lower dies are flat and horizontal.

Hammers are classified as

i)Mechanical Hammers

a)Helve and trip hammer,

b)Lever spring hammer, and

ii)Air and steam-hammers.

a)Pneumatic hammer.

Air and steam-hammers are sub classified into

a)Single and double acting hammers.

The capacity of a hammer is determined by the weight of the falling parts. The weight of the anvil and the reciprocating parts usually have a ratio 15 to 1 (anvil block).

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Mechinopedia For Mechanical Engineers

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