Shear system for cutting profile steel rods

Abstract

In a shear a workpiece is pressed by a holddown against a stationary blade so as to leave a piece to be cut off projecting past the blade, a movable blade is displaced forward past the stationary blade to cut off the piece, and a cut-off holder is pressed in back against the piece by a fluid-powered holding cylinder and moves back in the direction as the piece is cut off. Pressure is substantially completely relieved in the cylinder as soon as the movable blade starts to cut through the workpiece so that the cut-off holder does not substantially resist forward movement in the cutting direction. The movable blade is pressed forward in the direction against the workpiece by a main cylinder so that pressure in the main cylinder reaches a maximum level just before the movable blade starts to cut through the workpiece. The pressure in the main cylinder is monitored to trigger relief of pressure in the holding cylinder when the monitored pressure starts to decrease from the maximum level. It is also possible to monitor travel of the movable blade or cut-off holder and to trigger relief of pressure in the holding cylinder when the main blade or cut-off holder reaches a predetermined position. Similarly one can monitor elapsed time from the start of a cut through the workpiece and trigger relief of pressure in the holding cylinder a predetermined time after the cut starts.

Dependencies are inferred from the claim text.