Patent ID: 6914209
Filing Date: 2005-07-05
Classification: B23K

Abstract:
1. A plasma arc machining method in which a workpiece is pierced by a plasma arc and is cut from a piercing position, the plasma arc being formed by jetting plasma gas from a nozzle of a plasma torch such that the plasma arc is formed between an electrode of the plasma torch and the workpiece, said method comprising: positioning the plasma torch at an initial height with respect to the workpiece, said initial height being less than or substantially equal to a cutting height of the plasma torch with respect to the workpiece at which a cutting operation is performed, and said initial height being at a position at which a double arc does not occur; forming a main arc between the electrode and the workpiece by initiating a pilot arc between the electrode and the nozzle to form the main arc; relatively moving the plasma torch and the workpiece, while maintaining the main arc, to position the plasma torch at a piercing height with respect to the workpiece to perform a piercing operation, the piercing height being larger than the initial height; maintaining the main arc while the plasma torch is positioned at the piercing height, until completion of the piercing operation; and relatively moving the plasma torch and the workpiece to position the plasma torch at the cutting height to perform the cutting operation, after the completion of the piercing operation.