|
|
|
Hand Forging by Thomas F. Googerty
|
•FORGING PROCESSES 45
the punch in water once in a while, as it is liable to bend from the heat of the iron.
Light stock may be punched cold. In doing this the punch is the same size as the hole needed. It is better to use a short, thick, slightly tempered punch, which is not so liable to bend. In cold punching there is also used a punch block, which is a small, round or square block of iron with a steel face welded on it. The block may have different-sized holes in it. The holes are tapered,
Fig. 18. Punch Block
being larger at the bottom to let the burr from the punch drop out. The block should also be hardened to protect the face from damage while punching. (See Fig. 18.)
In cold punching, the piece that is to have the hole is set on the block directly over the hole in the punch block. A little oil is now rubbed on the punch, and it is set on the piece over the hole; with the hammer it is given one or two hard blows, driving the punch through the metal, at the same time cutting out a piece just the size of the hole in the block.
|
|
|
Hand Forging by Thomas F. Googerty