Welded portion inspection apparatus and inspection method thereof

Patent metadata

Field	Value
Publication number	US-9506862-B2
Application number	US-201414780584-A
Country	US
Kind code	B2
Filing date	Mar 28, 2014
Priority date	Mar 29, 2013
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A welding laser beam (L 1 ) is radiated along welding loci (C 11 , C 12 ) set in workpieces (W 1 , W 2 ), or an inspection laser beam (L 5 ) is radiated along scanning loci (C 51 , C 52 ) set in a molten pool (Y 1 ) of the workpieces (W 1 , W 2 ) that are molten by radiation of the welding laser beam (L 1 ), a returned light beam (L 2 ) including reflection light from the molten pool (Y 1 ) of the workpieces, vapor light caused due to melting and evaporation of the workpieces, and thermal radiation light emitted from the molten pool (Y 1 ) of the workpieces is received, and a welding state of a welded portion of the workpieces is inspected based on an intensity change of the returned light beam (L 2 ) thus received.

First claim

The invention claimed is:

1. A welded portion inspection apparatus that inspects a welding state of a welded portion formed at the time when a plurality of workpieces is welded, the welded portion inspection apparatus comprising:
a laser beam radiation portion that radiates a welding laser beam along a welding locus set in the workpieces so as to weld the workpieces, or radiates an inspection laser beam along a scanning locus set in a molten pool of the workpieces that are molten by the welding laser beam;
a laser-receiving sensor that receives a returned light beam including at least one of reflection light of the welding laser beam or the inspection laser beam radiated by the laser beam radiation portion, the reflection light being reflected from the molten pool of the workpieces, vapor light caused due to melting and evaporation of the workpieces, and thermal radiation light emitted from the molten pool of the workpieces; and
a measuring instrument that monitors an intensity change of the returned light beam received by the laser-receiving sensor at the time when the welding laser beam is radiated along the welding locus or at the time when the inspection laser beam is radiated along the scanning locus, in order to inspect a welding state of the welded portion of the workpieces, wherein:
the laser beam radiation portion radiates the welding laser beam several times along the same welding locus or radiates the inspection laser beam several times along the same scanning locus; and
the measuring instrument inspects the welding state of the welded portion of the workpieces based on a periodicity of the intensity change of the returned light beam at the time when the welding laser beam is radiated along the same welding locus or at the time when the inspection laser beam is radiated along the same scanning locus.

2. The welded portion inspection apparatus according to claim 1 , wherein:
a scanning period of the welding laser beam at the time when the welding laser beam is radiated along the same welding locus, or a scanning period of the inspection laser beam at the time when the inspection laser beam is radiated along the same scanning locus is the same as an unique period of the intensity change of the returned light beam which is obtained when the welding state of the welded portion is normal.

3. The welded portion inspection apparatus according to claim 1 , wherein:
the measuring instrument inspects the welding state of the welded portion of the workpieces by performing Fourier transform or differentiation on an intensity of the returned light beam.

4. A welded portion inspection method for inspecting a welding state of a welded portion formed at the time when a plurality of workpieces is welded, the welded portion inspection method comprising:
radiating a welding laser beam along a welding locus set in the workpieces so as to weld the workpieces, or radiating an inspection laser beam along a scanning locus set in a molten pool of the workpieces that are molten by the welding laser beam;
receiving a returned light beam including at least one of reflection light of the welding laser beam or the inspection laser beam which is reflected from the molten pool of the workpieces, vapor light caused due to melting and evaporation of the workpieces, and thermal radiation light emitted from the molten pool of the workpieces; and
inspecting a welding state of the welded portion of the workpieces based on an intensity change of the returned light beam received at the time when the welding laser beam is radiated along the welding locus or at the time when the inspection laser beam is radiated along the scanning locus, wherein:
in the radiating of the welding laser beam or the inspection laser beam, the welding laser beam is radiated several times along the same welding locus or the inspection laser beam is radiated several times along the same scanning locus; and
in the inspecting of the welded state, the welding state of the welded portion of the workpieces is inspected based on a periodicity of the intensity change of the returned light beam at the time when the welding laser beam is radiated along the same welding locus or at the time when the inspection laser beam is radiated along the same scanning locus.

5. The welded portion inspection method according to claim 4 , wherein:
in the radiating of the welding laser beam or the inspection laser beam, the welding laser beam is radiated along the same welding locus or the inspection laser beam is radiated along the same scanning locus at an unique period of the intensity change of the returned light beam which is obtained when the welding state of the welded portion of the workpieces is normal.

6. The welded portion inspection method according to claim 4 , wherein:
in the inspecting of the welded state, the welding state of the welded portion of the workpieces is inspected by performing Fourier transform or differentiation on an intensity of the returned light beam.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kobayashi Hiroomi
• Furukawa Masashi
• Uchida Keisuke
• Shibata Yoshinori
• Kawakita Atsushi
• Kishi Hiroaki
• Akamatsu Eiji
• Iwamoto Yuta

Classifications

• B23K26/03

  Observing, e.g. monitoring, the workpiece · CPC title

• G01N33/205

  in liquid state, e.g. molten metals · CPC title

• B23K26/032 Primary

  using optical means · CPC title

• B23K26/082

  Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head · CPC title

• B23K26/22

  Spot welding · CPC title