Abstract: Adhesion and accumulation of spatter onto a covering member that encloses the outer periphery of a torch is minimized and flying of spatter is confined within a narrow area. To this end, a covering member for enclosing a specified angular range of the outer periphery of a plasma torch 9 is provided and an opening portion 35 is formed between every adjacent shielding plates 34 in the covering member.

Abstract: Adhesion and accumulation of spatter onto a covering member that encloses the outer periphery of a torch is minimized and flying of spatter is confined within a narrow area. To this end, a covering member for enclosing a specified angular range of the outer periphery of a plasma torch 9 is provided and an opening portion 35 is formed between every adjacent shielding plates 34 in the covering member.

Abstract: An object of the present invention is, in plasma cutting using a plasma torch of the double-swirl type, to make it possible to maintain the bevel angle always constant, irrespective of the shape of the cutting line, and thereby to raise the accuracy of the cutting track. In locations where the cutting line is a straight line or a comparatively gentle curve, NC control unit 83 makes the cutting speed high and gas control unit 85 makes the secondary gas flow rate or secondary gas strength of rotation high. In locations where the cutting line is a corner or a comparatively sharp curve, NC control unit 83 makes the cutting speed low and gas control unit 85 makes the secondary gas flow rate or strength of rotation comparatively low. NC control unit 83 determines the speed of cutting in accordance with the magnitude of the curvature of the cutting line such that the positional offset between the upper kerf track and lower kerf track caused by the cutting lag is below a prescribed allowed value.