METAL-WORKING MACHINERY. 369 METAL-WORKING MACHINERY. franie ur yoke having at tlie eiuls cif tlii' 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. l'"ig. r> 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 (i])eratcd by hydraulic power. Pbe.sses. Presses are used for forming sheet metal into utensils of various forms by means of pressure between dies. They may be operated bv steam, hydraulic, or other power. Fig. 6 sfiows a hydraulic press for such work as watch- FlG. 7. BCLLDOZEB PRESS. tween which the plate is drawn by the rotation of the rolls. The relative adjustment of the rolls determines the curve to which the plate is bent. The accompanying plate shows a horizontal bend- ing roll operated by a special steam-engine and 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. Sawing JIaciiines. Saws are used extensively in metal-working for cutting plates and shapes into shorter lengths. They are built in a large number of forms both portable and stationary. In the illustration (Fig. 8) a familiar form of Fig. 6. HVDnACLic press. case making, which is operated by a belt-driven pump. The operation of presses of this style is described in the article on Hydraulic Press. Presses are made for both the hot and cold work- ing of metals. A form of hot-working press, gen- erally horizontal in action, u.sed in bending struc- tural shapes, is called a bulldozer. The illustra- tion shows a familiar form of bulldozer press. Be.ndixg iI.CHiNES. Bending rolls are used for bending metal plates to suitable curves for boiler and lank work. They usually consist of three rolls arranged in the form of a triangle be- FlG. 8. COLD METAL. SAWIXG MACHINES. toothed saw for cutting oft" steel beams and simi- lar shapes is shown; the beam is clamped to a carriage and moved into contact with the edge of a circular saw as is done in sawing lumber by similar saws. The toothless cold metal saw con- sists simply of a plain soft steel or iron disk with- out teethj about 42 inches in diameter and three- sixteenths of an inch thick. The velocity of the circumference in operation is about 15,000 feet per minute. One of these saws will cut through an ordinary steel rail in about one minute. In this saw the iron or steel is ground oil' by the friction of the disk, and is not cut as with the Fig. 9. plain milling machine. teeth of an ordinary saw. It has generally been found more profitable, however, to saw iron with disks or band saws, fitted with cutting teeth, which run at moderate speeds and cut the metals as do the teeth of a milling cutter such as is de- scribed in the succeeding section. A novel appli- cation of the cold saw is known as Reese's fusing disk. This saw is used to cut iron or steel in the form of bars, tubes, cylinders, etc., and the
