Hot machining of workpiece using plasma torch heat source - mounted for transverse movement in series of arcuate passes to soften workpiece ahead of machine tool (ZA 28.3.79)

摘要

A method of machining a workpiece comprises creating relative rectilinear movement between the workpiece and a plasma torch and cutting tool assembly with the plasma torch being in advance of the tool. The assembly is moved in a series of arcuate passes transversely of the workpiece with reference to the rectilinear movement. The speed of the arcuate movements and the torch intensity are controlled, in relation to the rectilinear movement to produce an evenly heated and softened region of the workpiece in advance of the cutting tool. The workpiece is evenly heated to avoid thermal damage and two successive passes of the heat source may be used. A sacrificial portion having a less degree of hardness than the main portion may be provided as a leading edge of the workpiece to lessen shock-loading on the cutting tool at the commencement of machining.