SHEARING MACHINES. Shears are used for cutting off or shearing metal plates and shapes, and resemble punches in construction and opera tion except that the punching tool and die are replaced by cutting edges which slide past each other like the blades of ordinary shears or scis sors. Fig. 4 shows a familiar construction of plate shears; machines of this type arc built wide enough to shear plates 10 feet wide. For shearing angle iron and other shapes special forms of shears are often made.
ordnance, hollow shafting. usually have a cylindrical tool head in which two or more separate tools arc clamped. They are designed to (kill horizontal, vertical or inclined holes, shows a three-spindle vertical boring ma chine. Drills and boring machines tire often used for reaming holes made by punching or for giving an exact cylindrical interior surface to a hollow casting. as, for example, an engine cylin der.
RlvlTING MACHINES OR 1: VETERS. Riveters are employed for driving and heading hot rivets in making riveted conneetions in boiler work, structural work, etc. They are built in a great variety of forms, but most usual is a U-shaped frame or yoke having at the ends of the arms interiorly projecting dies one of which is sta tionary while the other has a reciprocating mo tion. The rivet after being inserted in the hole is
squeezed endwise between these two dies until it clamps the work together and a head is formed. Fig. 5 shows a common form of riveter. The mov ing die is operated by means of a steam or com pressed air cylinder. Riveters are made sta tionary as well as portable; stationary riveters are usually employed for heavier work and are often operated by hydraulic power.
PnEssEs. Presses are used for forming sheet metal into utensils of various forms by means of pressure between dies. They may be operated by steam, hydraulic, or other power. Fig. 6 shows a hydraulic press for such work as watch used by the 'United States Government for bend ing 1 inch thick steel plates. These rolls will take in plates 24 feet wide. Vertical rolls of similar construction are also made.