Laser welding head-controlling system, a laser welding head and a method for controlling a laser welding head

• US 6,849,821 B2
• Filed: 05/08/2001
• Issued: 02/01/2005
• Est. Priority Date: 05/11/2000
• Status: Expired due to Fees

• Current Assignee: Hokkaido University
• Original Assignee: Hokkaido University
• Inventors: Ikeda, Masayuki, Mutoh, Masakazu, Kadono, Hisao, Ueda, Eisuke, Mukasa, Koichi, Sueoka, Kazuhisa
• Primary Examiner(s): Stoner, Kiley S.
• Assistant Examiner(s): Tran, Len
• Application Number:
  US09/851,261
• Publication Number:
  US 20020003129A1
• Time in Patent Office: 1,365 Days
• Field of Search: 219/121.63, 219/121.64, 219/121.83, 356/376, 356/604
• US Class Current: 219/121.63
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/044 Seam tracking

Abstract

A laser irradiating body with a laser inlet and a laser outlet is provided, and plural semiconductor lasers to oscillate plural linear laser beams for measuring a welding state are provided. Then, a CCD camera with a band-pass filter therein to pass through only the reflected linear laser beams is provided. The CCD camera takes, as an image, the measured welding state by the reflected linear laser beams in. Moreover, an image processor to process the image of the measured welding state is provided.

Claims

1. A laser welding head-controlling system comprising:

a laser irradiating body with a laser inlet and a laser outlet that directs a laser spot at a welding seam,

a plurality of semiconductor lasers to oscillate a plurality of linear laser beams configured to direct said plurality of the linear laser beams at welding seam or at a region already welded for measuring a welding state during or after a welding process,

a CCD camera with a band-pass filter therein to pass through only reflected laser beams from said linear laser beams and to take in, as an image, said welding state, and

an image processor to process said image relating to said welding state.

2. A laser welding head comprising a laser welding head-controlling system as defined in claim 1, a laser oscillator to oscillate a laser for welding and a condenser to converge the oscillated laser.

12. The laser welding head-controlling system according to claim 1, wherein at least one of said semiconductor lasers is on a side of said laser outlet opposite another one of said semiconductor lasers.

13. The laser welding head-controlling system as defined in claim 1, wherein each of said plurality of the semiconductor lasers is configured to direct its linear laser beam at said welding seam or said region already welded so as to be orthogonal to said welding seam or said region.

3. A method for controlling a laser welding head comprising the steps of:

irradiating a plurality of linear laser beams onto parts during or after a welding process to detect a welding state of the parts,

taking, as an image, said welding state on laser beams reflected by the parts into a CCD camera,

processing said image relating to said welding state, and

controlling a laser welding bead based on process data relating to said image.

4. A method for controlling a laser welding head as defined in claim 3, wherein the laser welding head is controlled by the CAD data of the parts to be welded.

5. A method for controlling a laser welding head as defined in claim 3, further comprising the step of monitoring welding defects of the parts to be welded based on the process data and the CAD data.

6. A method for controlling a laser welding head as defined in claim 4, further comprising the step of monitoring welding defects of the parts to be welded based on the process data and the CAD data.

14. The method for controlling a laser welding head as defined in claim 3, wherein the step of irradiating comprises irradiating each of said plurality of the linear laser beams at a welding seam of said parts so as to be orthogonal to said welding seam.

7. A laser welding head-controlling system for controlling the position of a laser welding head with respect to a target area of objects to be welded, comprising:

at least two semiconductor lasers for emitting linear laser beams configured to be crisscrossed over a seam line at a predetermined angle at the target area or at a region already welded for detecting a welding state during or alter a welding process;

a CCD camera provided with a band-pass filter, through which linear laser beams reflected by the object pass exclusively, to generate an image or the target area; and

an image processor for processing the image of the target area to determine the progress of welding, thereby controlling the position of a laser welding head.

8. The laser welding head-controlling system according to claim 7, further comprising a CAD data system which stores CAD data of the objects, said data being used to control the position of the laser welding head.

9. A laser welding head comprising the laser welding head-controlling system of claim 7, a laser oscillator to oscillate a laser for welding, and a condenser to converge the oscillated laser.

10. A method for controlling the position of a laser welding head with respect to a target area of objects to be welded, comprising the steps of:

emitting at least two linear lasers beams so as to be crisscrossed over a seam line at a predetermined angle toward the target area during or after a welding process to detect a welding state of the target area;

generating an image of the target area exclusively from linear laser beams reflected by the objects passing through a band-pass filter, using a CCD camera provided with the band-filter;

processing the image of the target area to determine the progress of welding; and

controlling the position of the laser welding head.

11. The method according to claim 10, further comprising using CAD data of the objects to control the position of the laser welding head.