Thermal and mechanical effects of high-speed impinging jet in orthogonal machining operations: Experimental, finite elements and analytical investigations

摘要

Changing environmental awareness has led manufacturing industry to give critical consideration to the use of conventional coolants and traditional cooling techniques in machining processes. This research shows that impinging gas jets have a much greater potential for reducing the temperature in cutting operations than previously suspected. In this work, the mechanical effect produced by a high-speed air jet impinging on the cutting area at different directions and pressures was critically investigated. Experimental tests with different pressures and nozzle directions indicate that the mechanical effect of the air jet contributes significantly to the reduction in cutting temperature. The tests were carried out on AISI 1020 workpiece and the temperature was measured by a K-type thermocouple embedded in the WC insert. Better performance in terms of cooling is shown when the air jet is directed onto the top face of the chip. The air jet impinging on the surface of the workpiece in the contact zone, on the tool and on the chip introduces both thermal and mechanical effects. Heretofore, these influences have not been examined together. Finite element analysis shows that the mechanical effect of the air jet, impinging on the chip, causes an alteration of the state of stress on the rake face. A theoretical explanation based on this observation is proposed, and the results of experimental, finite elements and analytical modeling are compared.