Patent ID: 8410395
Filing Date: 2013-04-02
Classification: B23K

Abstract:
1. A method for determining a reference focal position of a focused laser beam passing through an opening in a nozzle body of a laser processing nozzle relative to a workpiece, the method comprising: producing a continuous cutting line in the workpiece by simultaneously cutting off a portion of the workpiece using the focused laser beam and altering a distance between a focal point of the focused laser beam and the workpiece along a direction of a central axis of the laser beam, wherein a boundary of the continuous cutting line is defined by a continuous workpiece edge formed by the cutting; determining coordinates of the edge, wherein determining coordinates of the edge comprises contacting the edge with a mechanical touch tool, and the mechanical touch tool comprises the nozzle body of the laser processing nozzle or a measuring probe mounted on a laser processing head, and wherein an extent to which the continuous edge protrudes from the workpiece varies based on a change in focal position of the focused laser beam during the cutting; performing an operation selected from the list consisting of i) detecting a short circuit between the workpiece and the mechanical touch tool when the mechanical touch tool contacts the edge, ii) measuring a capacitance between the mechanical touch tool and the workpiece and detecting contact with the edge based on the capacitance measured, and iii) combinations thereof; determining, based on the coordinates, a section of the edge that protrudes furthest from the workpiece; and establishing a reference focal position (FL) of the laser beam based on the coordinates corresponding to the section of the edge that protrudes the furthest from the workpiece.