On Chip Curl in Metal Cutting under Gas Jets

Experimental Study on Metal Cutting under Jet Flow (3rd Report)

Abstract

In the cutting operations which are jetted the active gases for the cutting point of medium carbon steel S43C (JIS) from the direction along the side rake face, the chips are easily curled in certain cutting conditions. And so, this paper describes the results of an investigation into the better conditions of jet and causes for the chip curl from the experiments of aerodynamics and the cutting tests under various gas jets and high pressure of various gases. The main results obtained are as follows :
(1) For the better conditions of jet, it is found that the better distance between the side cutting edge and the nozzle measured on the rake face should be decided approximately 9 mm, and the better jet angle should be selected within the range of angles for the horizontal jet angle θ_h=0°20° and the vertical jet angle θ_v=0°6° on the rake face.
(2) The chips are not curled in the metal cutting under the high pressure of gases (A r, N₂, Air and a mixture of 50% each of O₂ and N₂), because the chips are cooled and the jet pressure on the chip surface under gas jets are produced little under high pressure of these gases. But, the chips are curled under high pressure of CO₂, because the necessary conditions to curl the chip are sufficiently satisfied by the environment of CO₂ and its pressure.
(3) The experimental equations to determine the critical cutting speed under which the chips curl are obtained from the chips which are made in the cutting operations under various gas jets.