ANALYSIS OF CUTTING METHODS FOR LARGE SECTION HOT STEEL BILLETS

Abstract

During equipment selection for cutting large section billets heated to 750‒1000°C the three cutting methods were analyzed: the method of gas cutting, the method of plastic shearing using shears, the method of cutting with saws. The saws use a thin disc with profiled teeth as a cutting tool. The blade performs two movements: rotation at a circumferential speed of 70‒110 m/s, which is called the cutting speed, and movement relative to the centre of the workpiece to be cut, which is called the feed. The high performance cutting with saws can be achieved by increasing the feed rate. This increases the thickness of the cuttings to be removed. The tests on force feed modes have shown that the cutting forces increase to a lesser extent than the thickness of the material removed. The quality of the cut is not impaired and the service life of the discs increases significantly. These results have been taken into account during design of the rotary saws with feed speeds increased to 1‒2 m/s. For the cutting process in rotary saws the planetary movement of the rotating cutting disc is realised. The feed to the cut is carried out by starting and stopping the cutter with 360° rotation. The energy reserve necessary for cutting is accumulated in the rotary flywheel, which is installed in the rotation line of the cutting disc from a separate motor, and the feed to the cut is carried out from the drive motor of the driver. Diagrams of mechanisms ensuring necessary technological modes of the hot billet cutting by means of saw blades are considered.