Increasing Structural Strength of Tillage Machines’ Working Bodies

Abstract

According to the analysis of published materials, the design with an attachable chisel has enjoyed the broadest use because it has a monolithic nose part with an additional component (chisel) that provides extra strength to this area. The force impact of the soil environment on the facial surface of the plowshare nose is analyzed. In most cases, the plowshare fails by breakdown and deformation in the zones of the nose and the first fastener hole. According to the theory of elasticity, this hole is the point of support for the cantilever beam with an arm extended from the first fastener hole to the blade perpendicular to the weak section line. The cantilever beam with regard to the plowshare nose is a triangle with a continuously increasing cross section from the blade to the first fastener hole; that is why failures may occur in any point along the arm line, whatever the arm length. It has been established that, when the chisel is mounted on the plowshare with side faces made parallel to the landward edge line, the strength of the tip increases on the plowshoe with all the fastener holes arranged in a single line, but the zone of the first fastener hole becomes weaker because extra force is generated that produces the bending torque and the rotational torque under the soil pressure. It has been shown that the plowshare strength in the zone of the first fastener hole is increased by mounting the attachable chisel so that the line along the side faces of the chisel splits the chisel into two equal parts by form and area and passes through the first fastener hole perpendicularly to the weak section and crosses the holes for fastening the chisel to the plowshare frame. Thus, the forces that cause the bending torque in the cantilever beam fastening point, i.e., in the first fastener hole, will be active only along one line perpendicular to the weak section line. This way the strength in the weak section zone close to the first fastener hole will increase because the impact of other extra soil forces will be minimized.