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FORGING PROCESSES 47 It may then be caught in a vise and bent at right angles, or it may be bent over the edge of the anvil. If the corner of an angle is to be a square one it must not be bent in a vise, as the jaws of the vise are liable to fracture the grain. Another reason is that the inner corner of the angle is made sharp by the jaws of the vise, and any working it receives afterward in making the corner square will cause it to crack. Perhaps the best method of working a square corner is to heat the bar at the place it is to be bent and bend it nearly at right angles over the edge of the anvil, leaving the corner round as shown in Fig. 19 at A. The corner is then heated and worked square by hammering it on the outside of corner as shown in the drawing. The corner must not be hammered while the piece is square, but must be kept at the angle shown at C. The reason for this is that the blows of the hammer must upset the outer corner. If it is hammered while the piece is in the shape shown at D, the inner corner will upset and form a crack. It must therefore be kept at the angle as shown at C and not allowed to get out of shape while upsetting. If a crack should start to form at the inner corner by this method of hammering, which is sometimes the case, it must then be drawn out by hammering each side of the crack as shown by the arrows at B. This hammering will draw the metal away from the crack, |
Hand Forging by Thomas F. Googerty