Distribution of contact loads over the flank-land of the cutter with a rounded cutting edge

Abstract

In this paper, contact conditions between a tool and a workpiece material for wear-simulating turning by a cutter with a sharp-cornered edge and with a rounded cutting edge are analysed. The results of the experimental study of specific contact load distribution over the artificial flank wear-land of the cutter in free orthogonal turning of the disk from titanium alloy (Ti[6]Al[2]Mo[2]Cr), ductile (63Cu) and brittle (57Cu1Al[3]Mn) brasses are described. Investigations were carried out by the method of 'split cutter' and by the method of the artificial flank-land of variable width. The experiments with a variable feed rate and a cutting speed show that in titanium alloy machining with a sharp-cornered cutting edge the highest normal contact load ([sigma][h max]=3400...2200 MPa) is observed immediately at the cutting edge, and the curve has a horizontal region with the length of 0.2... 0.6 mm. At a distance from the cutting edge, the value of specific normal contact load is dramatically reduced to 1100...500 MPa. The character of normal contact load for a rounded cutting edge is different -it is uniform, and its value is approximately 2 times smaller compared to machining with a sharp-cornered cutting edge. In author's opinion it is connected with generation of a seizure zone in a chip formation region and explains the capacity of highly worn-out cutting tools for titanium alloys machining. The paper analyses the distribution of tangential contact loads over the flank land, which pattern differs considerably for machining with a sharp-cornered edge and with a rounded cutting edge