Kinematics of Metallurgical Cutters with Parallel Blades

Abstract

Abstract—In the operation of cutters with parallel blades, three periods may be identified: pressing of blades into the metal; cutting; and cleavage (separation). The greatest force is required around the onset of cutting. Since one of the blades is immobile, the other must pass through the whole thickness of the metal in the course of cutting. For example, if the metal thickness is 20 mm, the upper blade must travel a distance of 20 mm to complete the cutting process. In the case of two mobile blades moving in opposite directions, the cutting forces will be less. If the metal thickness is 20 mm, each blade must travel a distance of 10 mm in the complete cutting process. To simplify the design in the case of two mobile blades, they must both be powered by a single drive. The question that arises here is whether opposing motion of the blades is possible with guaranteed strength of the components transmitting the force to the blades. A kinematic cutter design with blades that move in parallel within the vertical plane is proposed. A benefit of this design is that, in opposing cutter motion, less cutting force is required. In addition, the force from each blade is distributed to two rods, with decrease in the load on each one. Since the blades move in opposite directions, the main cutting force is distributed over the components of the mechanism and transmitted to the motor. That decreases the load on the frame and the foundation in cutting. In opposing motion of the blades, cleavage of the metal occurs more rapidly. That permits concentration of the maximum force at the cut, with minimum load on the motor. The section removed from the metal does not travel under the roller at the end of cutting, and therefore no lower mobile table is required. The degree of mobility of the proposed mechanism is determined from the Chebyshev formula; its value is one. A special method is used for kinematic analysis of the blades; this method is based on the point of intersection of the connecting rods.