Roughness of Ploughshare Working Surface and Mechanisms of Wear during Operation in Various Soils

Abstract

The condition of working surfaces of ploughshares used in two soils with different granulometric condition (one containing large portion of coarse fractions and one containing increased portion of fine fractions) was evaluated. The soil cultivated for the research was characterised by high moisture content. In the tests, divided ploughshares were used, composed of separate parts: a share-points and a trapezoidal part. The aim of the research was to determine, on the grounds of scanning microscopy of working surfaces and their roughness measurements, wear processes occurring during operation of the ploughshare. It was found from the scanning photography that the main mechanism for material wear in soils containing an increased portion of coarse grains was microcutting and grooving, but in soils containing increased portion of fine fractions, microcutting dominated. Surface roughness of ploughshares used in soil with increased portion of coarse grains was higher than that of ploughshares working in soil with higher portion of fine fractions. It was found by statistical analysis that in soil with an increased portion of coarse grains, values of the parameters Ra (arithmetical mean deviation of the assessed profile), Rt (maximum height of the profile), Rv (maximum valley depth) and Rp (maximum peak height), most often occurring on ploughshare rake face, were 1.13, 10.50, 7.60, 2.74 µm respectively and, in soil with an increased portion of fine fractions, these values were 0.80, 6.86, 4.78 and 2.32 µm respectively. On working surfaces of ploughshares operating in both types of soil, higher values Rv in relation to Rp were found. In average, ratio of these parameters for ploughshares in both soils was ca. 2.7. This indicated that microcutting and scratching occurred in the process of material wear of a ploughshare.