Method of starting a transferred-arc plasma-cutting torch by displacing the torch, and associated installation

摘要

The process comprises positioning a torch at a starting height (H a) provided with respect to an upper surface of a piece to be cut and initiating a pilot arc at a pilot intensity (I o) of non-zero, reconciling the torch of the upper surface of the piece to a transfer height (H 1) that is less than H aand transferring the pilot arc towards the piece, estranging the torch of the upper surface of the piece to a drilling height (H 2) that is greater than H aand starting the hole of the piece, and supplying a pilot gas during the positioning and reconciling steps. The process comprises positioning a torch at a starting height (H a) provided with respect to an upper surface of a piece to be cut and initiating a pilot arc at a pilot intensity (I o) of non-zero, reconciling the torch of the upper surface of the piece to a transfer height (H 1) that is less than H aand transferring the pilot arc towards the piece, estranging the torch of the upper surface of the piece to a drilling height (H 2) that is greater than H aand starting the hole of the piece, supplying a pilot gas during the positioning and reconciling steps, and stopping the supply of the pilot gas and supplying a cutting gas from the transfer of the pilot arc to the piece. During the reconciling step, the pilot intensity (I o) is gradually increased to a cutting intensity (I 1) that is greater than I o. The step of gradually increasing the pilot intensity is performed during a given period (T r) that is less than T p, which is total duration of the drilling step. The torch is maintained at the transfer height (H 2) during the total duration of the drilling step (T p) so as to maintain the cutting intensity (I 1) during the duration of the drilling period (T d). A translational displacement movement of the torch is operated with respect to the piece according to a path including: the maintenance of the first torch to the transfer height for a period of start of cutting data and the gradual alignment of the torch relative to the piece to a cutting height (H 3) after the starting period. The method further comprises, before the positioning step, positioning a first torch to an initial height (H o) above a cutting plate, reconciling the torch of the upper surface of the piece to an electrical contact established between the torch and the piece, and estranging the torch to the starting height. Independent claims are included for: (1) a process for plasma cutting of a metal part; and (2) a plasma cutting installation.