ABSTRACT
Squaring shears are the foremost machine tools used for processing strip, coil stock, or large sheets of metal into smaller strips or blanks for subsequent fabricating operations.
Because of the mechanics involved in the action of shearing, the squaring shear is able to make straight-line cuts in long sections of metal more efficiently than other metal-cutting operations. In the shearing process, the blades do not have to cut through the full thickness of the material to complete the cutting operation, as is required with most other metal-cutting machines. In shearing, the blades only have to penetrate the material to a percentage of thickness to overcome the tensile stress, to cause a fracture on both sides of the metal. After the fracture, or what is referred to as the slip plane, occurs, the rest of the metal breaks away. With this advantage, and with the fast-stroke cycles of squaring shears, the time to complete a cut is minute. As an example, to shear 10ft. of 0.375-in. mild steel on a hydraulic shear that is rated at 14 strokes per minute, the time to complete a full-length cut is 4 s. A mechanical shear with the same capacity rating will complete a full-length cut in about 2.5 s.
