Method for Optically Measuring the Weld Penetration Depth

Patent metadata

Field	Value
Publication number	US-2019041196-A1
Application number	US-201816041251-A
Country	US
Kind code	A1
Filing date	Jul 20, 2018
Priority date	Aug 1, 2017
Publication date	Feb 7, 2019
Grant date	—

Abstract

Embodiments pertain measuring the weld penetration depth, particularly in welding, drilling or machining processes carried out by means of a working laser beam, wherein a measurement light beam of a sensor system is coupled into a processing beam path of the working laser beam in a laser machining head and bundled or focused into a measurement light spot on the surface of a workpiece by means of focusing optics of the processing beam path. The measurement light beam reflected on the surface of the workpiece is then returned to a measurement and evaluation unit of the sensor system in order to obtain information on the distance of the surface of the workpiece from the laser machining head. In order to obtain a surface profile of the workpiece in the region of the vapor capillary, from which the position of the vapor capillary relative to the point of incidence of the working laser beam can be determined, the position of the measurement light spot on the surface of the workpiece is guided over the vapor capillary in the welding direction, as well as transverse to the welding direction. The measurement light spot is during the subsequent laser machining process moved into the determined position of the vapor capillary in order to measure the weld penetration depth.

First claim

What is claimed is:

1 . A method for measuring the weld penetration depth, particularly in welding, drilling or machining processes carried out by means of a working laser beam, wherein
a measurement light beam of a sensor system is coupled into a processing beam path of the working laser beam in a laser machining head and bundled or focused into a measurement light spot on the surface of a workpiece by means of focusing optics of the processing beam path, the measurement light beam reflected on the surface of the workpiece is returned to a measurement and evaluation unit of the sensor system in order to obtain information on the distance of the surface of the workpiece from the laser machining head, the position of the measurement light spot on the surface of the workpiece is guided over the vapor capillary in the welding direction, as well as transverse to the welding direction, in order to obtain a surface profile of the workpiece in the region of the vapor capillary, the position of the vapor capillary relative to the point of incidence of the working laser beam is determined from the surface profile of the workpiece in the region of the vapor capillary, and the measurement light spot is during the laser machining process moved into the determined position of the vapor capillary in order to measure the weld penetration depth.

2 . The method according to claim 1 , wherein the lowest point of the vapor capillary is determined as the position of the vapor capillary relative to the point of incidence of the working laser beam.

3 . The method according to claim 1 , wherein the measurement light spot is guided over the vapor capillary on linear paths.

4 . The method according to claim 3 , wherein the surface profile is determined from the measurement data along the linear paths by means of curve fitting.

5 . The method according to claim 4 , wherein the surface profile is determined from the measurement data along the linear path transverse to the welding direction by means of curve fitting according to a Gaussian distribution.

6 . The method according to claim 4 , wherein the surface profile is determined from the measurement data along the linear path in the welding direction by means of curve fitting according to a Maxwell-Boltzmann distribution.

7 . The method according to claim 1 , wherein the measurement light spot is guided over the vapor capillary on spiral-shaped paths.

8 . The method according to claim 1 , wherein the position of the vapor capillary relative to the point of incidence of the working laser beam is determined for predefined process parameters of a machining process during a test machining run and stored as the measurement spot position for this machining process.

9 . The method according to claim 8 , wherein the respective positions of the vapor capillary relative to the point of incidence of the working laser beam are determined for predefined process parameters of different machining processes during test machining runs and stored as the measurement spot positions for these machining processes.

10 . The method according to claim 8 , wherein the measurement spot position stored for the corresponding process parameters is adapted to the respective advance direction for a machining process, in which the advance direction changes during the course of the machining process.

11 . A device for measuring the weld penetration depth, particularly in welding, drilling or machining processes carried out by means of a working laser beam, comprising:
a laser machining head, through which a processing beam path with focusing optics for focusing the working laser beam on a workpiece extends, a sensor system for generating a measurement light beam, which can be coupled into the processing beam path in the laser machining head and bundled or focused in a measurement light spot on a surface of the workpiece by means of the focusing optics of the processing beam path, and an actuator system with a deflection unit for the measurement light beam, wherein the sensor system and the actuator system are configured for carrying out a method for measuring the weld penetration depth according to one of the preceding claims.

Assignees

• Precitec Gmbh & Co Kg

Inventors

• Strebel Matthias

Classifications

• G01B11/22 Primary

  for measuring depth · CPC title

• G01B11/303

  using photoelectric detection means · CPC title

• B23K26/382

  by boring · CPC title

• B23K26/21

  by welding · CPC title

• B23K31/125

  Weld quality monitoring · CPC title