Laser welding method

Patent metadata

Field	Value
Publication number	US-9776280-B2
Application number	US-201514935002-A
Country	US
Kind code	B2
Filing date	Nov 6, 2015
Priority date	Nov 18, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A laser welding method is capable of easily restraining poor welding when spatters adhere to a protective glass of an optical system. The laser welding method includes a step of calculating a decrease-amount of the laser power before laser welding is performed by irradiating a welding portion of a workpiece with the laser beam having a predetermined power. The step of calculating the decrease-amount includes irradiating the welding portion with an inspecting laser beam having a power smaller than the predetermined power, receiving a return beam of the inspecting laser beam, measuring an intensity of the return beam, and comparing the intensity of the return beam with a standard intensity to calculate an amount of decrease in power of the inspecting laser beam at the welding portion.

First claim

What is claimed is:

1. A laser welding method for performing laser welding to welding portions of a workpiece, using a laser processing device including: (a) a laser oscillator; (b) an optical system which irradiates the welding portion with a laser beam emitted from the laser oscillator; (c) a protective glass which is arranged at an end part of the optical system facing the welding portion; (d) an optical receiver which receives a return beam that is incident into the optical system from reflection of the laser beam by the welding portion; and (e) a controller which controls an output of the laser oscillator based on an intensity of the return beam received by the optical receiver,
the laser welding method, comprising:
(1) calculating a decrease amount of the laser power before the welding portion is irradiated with the laser beam having a predetermined power, calculating the decrease amount including:
(1a) emitting an inspecting laser beam having a power smaller than the predetermined power to the welding portion with the laser oscillator and the optical system;
(1b) receiving the return beam of the inspecting laser beam having passed through the protective glass with the optical receiver;
(1c) measuring an intensity of the return beam of the inspecting laser beam with the controller; and
(1d) calculating, with the controller, an amount of decrease in power of the inspecting laser beam by comparing the intensity of the return beam of the inspecting laser beam with a previously-determined standard intensity of the return beam of the inspecting laser beam,

(2) adjusting the output of the laser oscillator, using the controller, based on the calculated amount of the decrease in power of the inspecting laser beam; and
(3) emitting the laser beam at the adjusted output to the welding portion to perform the laser welding with the laser processing device.

2. The laser welding method according to claim 1 , further comprising:
calculating a focal-deviation-amount after the laser welding has been performed to the welding portion at least once and before the laser welding is performed to a next welding portion, calculating the focal-deviation-amount including:
emitting the inspecting laser beam to the next welding portion with the laser oscillator and the optical system;
receiving the return beam of the inspecting laser beam from the next welding portion with the optical receiver;
measuring the intensity of the return beam of the inspecting laser beam from the next welding portion with the controller; and
calculating, with the controller, an amount of focal deviation of the laser beam at the next welding portion based on the intensity of the return beam of the inspecting laser beam from the next welding portion and the amount of the decrease in power of the inspecting laser beam calculated in the step (1) of calculating the decrease amount of the laser power.

3. The laser welding method according to claim 2 , further comprising:
adjusting a focal length of the laser beam with a focus adjuster of the optical system based on the calculated amount of the focal deviation, after performing the step of calculating the focal-deviation-amount and before the laser welding is performed to the next welding portion by the laser processing device; and
performing the laser welding to the next welding portion with the laser processing device after adjusting the focal length.

Assignees

• Toyota Motor Co Ltd

Inventors

• Ogura Shuhei
• OGUSU Kazuyuki
• Makino Jyunichiro
• Kishi Hiroaki
• Tsuji Kousuke

Classifications

• B23K31/125

  Weld quality monitoring · CPC title

• B23K26/032

  using optical means · CPC title

• B23K26/046 Primary

  Automatically focusing the laser beam · CPC title

• B23K26/705

  Beam measuring devices · CPC title

• B23K26/706 Primary

  Protective screens · CPC title