In order to control the height between torch-tip and workpiece at the plasma CNC cutting system, the digital controller and its algorithmwas were proposed in this thesis. Computer-Numerical Control has been increasingly attractive for manufacturing system, because of the low cost and outstanding capatbilities of current microcomputers. In this CNC system, the gap distance was measured by arc sensor and the the motion of Z-axis was controlled to maintain the constant height between torch-tip and workpiece during cutting. The arc sensor for the weld seam tracking in arc welding process is well-known, but the studies on the arc sensor for the plasma arc cutting has not been actively performed by now. Thus the characteristics of cutting arc sensor developed in this study were compared with that of welding arc sensor. Experiments and mathematical modelling were performed to determine the dominant cutting parameters which affect the arc voltage between torch-tip and workpiece.
The problems mentioned below were solved using the digital height controller proposed.
-uneven height distribution caused by loading workpiece
-thermal distortion by large heat input during cutting
-cutting the curved plate
We hope that developed plasma CNC cutting system involving digital height controller will be widely used.
