Laser welding quality inspection method and laser welding quality inspection apparatus

Patent metadata

Field	Value
Publication number	US-2021107096-A1
Application number	US-202017031984-A
Country	US
Kind code	A1
Filing date	Sep 25, 2020
Priority date	Oct 9, 2019
Publication date	Apr 15, 2021
Grant date	—

Abstract

A laser welding quality inspection method of a welded portion between a joining object and a joined object, when the joining object and the joined object are welded by being irradiated with a laser beam, the method includes: acquiring first data indicating a signal intensity of thermal radiation light radiated from the welded portion during the welding; acquiring second data indicating a signal intensity of plasma light radiated from the welded portion during the welding; and determining whether or not the welded portion includes an abnormality based on a comparison between the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired.

First claim

What is claimed is:

1 . A laser welding quality inspection method of a welded portion between a joining object and a joined object, when the joining object and the joined object are welded by being irradiated with a laser beam, the method comprising:
acquiring first data indicating a signal intensity of thermal radiation light radiated from the welded portion during the welding; acquiring second data indicating a signal intensity of plasma light radiated from the welded portion during the welding; and determining whether or not the welded portion includes an abnormality based on a comparison between the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired.

2 . The laser welding quality inspection method of claim 1 ,
wherein the determining whether or not the welded portion includes an abnormality based on a comparison between the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired includes calculating a difference signal indicating a difference between the signal intensity of the thermal radiation light and the signal intensity of the plasma light, and determining that the welded portion includes an abnormality when the calculated difference signal includes a peak having a signal intensity larger than a preset determination reference value.

3 . The laser welding quality inspection method of claim 2 , further comprising:
acquiring an irradiation output waveform indicating an intensity of irradiation light of the laser beam by measuring the irradiation light of the laser beam during the welding, wherein the calculating a difference signal indicating a difference between the signal intensity of the thermal radiation light and the signal intensity of the plasma light further includes setting, as a determination period, a period during which the intensity of the irradiation light of the laser beam is constantly maintained, based on the irradiation output waveform, and extracting the signal intensity of the thermal radiation light within the determination period and the signal intensity of the plasma light within the determination period respectively from the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired, and wherein the calculating a difference signal indicating a difference between the signal intensity of the thermal radiation light and the signal intensity of the plasma light includes calculating a difference between an intensity of the thermal radiation light within the determination period and an intensity of the plasma light within the determination period.

4 . The laser welding quality inspection method of claim 3 ,
wherein the calculating a difference signal indicating a difference between the signal intensity of the thermal radiation light within the determination period and the signal intensity of the plasma light within the determination period includes calculating a normalization signal of the thermal radiation light and a normalization signal of the plasma light by respectively normalizing the signal intensity of the thermal radiation light within the determination period and the signal intensity of the plasma light within the determination period, and calculating a difference signal indicating a difference between the normalization signal of the thermal radiation light and the normalization signal of the plasma light.

5 . The laser welding quality inspection method of claim 4 ,
wherein in the calculating a normalization signal of the thermal radiation light and a normalization signal of the plasma light, the following expressions are satisfied
Hm ( t )=( H ( t )− m av )/ m av   [Equation 1]:

Sn ( t )=( S ( t )− n av )/ n av   [Equation 2]:

where m av is an average value of the signal intensity of the thermal radiation light within the determination period, n av is an average value of the signal intensity of the plasma light within the determination period, H(t) is a time function of the signal intensity of the thermal radiation light before being normalized within the determination period, S(t) is a time function of the signal intensity of the plasma light before being normalized within the determination period, Hm(t) is a time function of the normalization signal of the thermal radiation light within the determination period, and Sn(t) is a time function of the normalization signal of the plasma light within the determination period.

6 . The laser welding quality inspection method of claim 4 ,
wherein in the calculating a normalization signal of the thermal radiation light and a normalization signal of the plasma light, the following expressions are satisfied
Hm ( t )=( H ( t )− m av ( t ))/ m av ( t )  [Equation 3]:

Sn ( t )=( S ( t )− n av ( t ))/ n av ( t )  [Equation 4]:

where m av (t) is an average value of a time function of the signal intensity of the thermal radiation light of a plurality of times of welding determined to have no abnormality in the welded portion within the determination period, n av (t) is an average value of a time function of the signal intensity of the plasma light of the plurality of times of welding within the determination period, H(t) is a time function of the signal intensity of the thermal radiation light before being normalized within the determination period, S(t) is a time function of the signal intensity of the plasma light before being normalized within the determination period, Hm(t) is a time function of the normalization signal of the thermal radiation light within the determination period, and Sn(t) is a time function of the normalization signal of the plasma light within the determination period.

7 . A laser welding quality inspection apparatus for a welded portion between a joining object and a joined object, when the joining object and the joined object are welded by being irradiated with a laser beam, the apparatus comprising:
a measurement device; and a welding state determination device, wherein the welding state determination device includes a signal intensity acquisitor that acquires, from the measurement device, first data indicating a signal intensity of thermal radiation light radiated from the welded portion during welding, and second data indicating a signal intensity of plasma light radiated from the welded portion during the welding, and a signal intensity processor that executes processing of the first data and the second data acquired by the signal intensity acquisitor, and wherein the signal intensity processor determines whether or not the welded portion includes an abnormality based on a comparison between the signal intensity of the thermal radiation light and the signal intensity of the plasma light which are acquired.

8 . The laser welding quality inspection apparatus of claim 7 ,
wherein the signal intensity processor calculates a difference signal indicating a difference between the signal intensity of the thermal radiation light and the signal intensity of the plasma light based on the first data and the second data, and determines that the welded portion includes an abnormality when the calculated difference signal includes a peak having a signal intensity larger than a preset determination reference value.

9 . The laser welding quality inspection apparatus of claim 8 ,
wherein the signal intensity acquisitor further acquires an irradiation output waveform indicating an intensity of irradiation light of the laser beam from the measurement device, wherein the signal intensity processor sets, as a determination period, a period during which the intensity of t

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Funami Koji

Classifications

• B23K26/707

  for monitoring laser beam transmission optics · CPC title

• B23K26/00 Primary

  Working by laser beam, e.g. welding, cutting or boring · CPC title

• B23K26/70

  Auxiliary operations or equipment · CPC title

• B23K31/125 Primary

  Weld quality monitoring · CPC title

• B23K2103/10

  Aluminium or alloys thereof · CPC title