SAWING MACHINE

device for cutting up bars of material or for cutting out shapes in plates of raw material. The cutting tools of sawing machines may be thin metallic disks with teeth on their edges, thin metal blades or flexible bands with teeth on one edge, or thin grinding wheels. The tools may use any of three actions in sawing: true cutting, grinding, or friction-created melting. The power hacksaw machine provides a vise for clamping the work and means for reciprocating a U-shaped frame on which is mounted a straight steel hacksaw blade that cuts when moving in one direction only. The saw presses down on the work during the cutting stroke but is raised clear of the work during the return stroke. The band saw employs an endless flexible steel band with teeth on one edge; the band is carried on two large-diameter rotating wheels mounted on parallel axes some distance apart. Band saws that cut vertically are particularly suitable for cutting out shapes in thin, flat plates from workpieces that lie on horizontal tables. Cold-sawing machines with toothed disk cutters are used extensively in steel-rolling mills and in places where large quantities of bars are cut. A V-shaped clamping vise enables bundles of bars to be clamped and cut at one time. Friction-sawing machines are used largely for cutting off steel structural shapes such as I beams, channels, and angles. The cutting wheels, with or without teeth, rotate at such high speeds that the heat from the friction of contact is sufficient to remove the metal by melting it. Abrasive cutoff saws, thin rubber or Bakelite-bonded abrasive wheels that are operated at high peripheral speeds, are particularly suitable for cutting off thin tubes and hardened steel bars.