Study of cutting temperature during turningof high-hard cast irons

Abstract

Purpose. To study the forces and temperature in the cutting zone during machining of high-hard cast iron with special prefabricated cutters with brazed niborite and ciborite inserts. To determine the influence of geometric characteristics of the cutting tool, cutting modes and hardness of the material being machined on the temperature. The methods. The research methods were based on the basics of cutting theory and cutting tools, material science properties of the tool and the material being processed. The research stand with special equipment was used. Findings. The nature of the change in cutting forces temperature with depth t, feed rate S and cutting speed v was experimentally investigated. A non-contact method of measuring the temperature in the cutting zone during turning high-hard cast irons of different chemical composition with cutting inserts made of niborite and ciborite PSM has been substantiated. It is shown that different measurement conditions (turning modes, cutting geometry and the degree of blunting of the cutters, hardness and grade of the machined steel) do not allow determining the average proportionality coefficient CQ. The hardness of the material being machined affects the cutting forces and temperature. Under identical turning conditions for cast irons with a hardness of 220 to 610 HB, the temperature increases by 1,9 times. It has been experimentally established that with the growth of normal and tangential forces on the back surface of the cutter as its wear develops, an additional increase in the total cutting force and heat source power is observed –the temperature increases by 1,3 times. The originality. It was found that the increase in cutting temperature is associated with an outstripping increase in heat generation power over the heat removal rate (with a deterioration in the conditions of heat removal from the top of the blade). The influence of the geometric parameters of the tool and the hardness of the material being machined on the temperature during turning of high-hard cast irons has been proved. Practical implementation. The experimental data obtained will make it possible to develop a mathematical model taking into account the geometric parameters of the tool, the hardness of the material being processed, and the power and energy parameters of the cutting process.