Apparatus and method for performing laser welding operations

Abstract

A laser welding apparatus and method reproduces a welding state substantially identical to an actual operation of a robot at a manufacturing site even when an operating speed of the robot is changed. When a moving speed of the robot is, for example, 50% of an override ratio, a welding point speed, which is a resultant speed of a focus moving speed of the laser beam by movement of the robot having a scanner head and the focus moving speed of the laser beam by rotation of the laser scanning mirror, becomes identical to that when an override ratio is 100%. This is achieved by increasing a rotating speed of a laser scanning mirror within the scanner head.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

FIG. 1 is a schematic view illustrating a laser welding apparatus;

FIG. 2 is a diagram illustrating an inner part of a scanner head;

FIG. 3 is a flow chart illustrating processing sequences during an override operation (i.e., when a robot speed becomes slower);

FIG. 4 is a time chart illustrating when an override operation is performed in accordance with embodiments of the invention;

FIG. 5 is a time chart illustrating when a conventional override operation is performed as a comparative example;

FIG. 6 is a graph showing a laser power value causing a welding point speed change to be the same as a heat input amount during an actual operation; and

FIG. 7 is a graph showing a laser power value relating to a welding speed for explaining an override ratio change.

Claims

1. A laser welding apparatus for performing welding by irradiating a laser beam, the apparatus comprising: a laser oscillator operable to generate a laser beam;a laser irradiating device having a reflecting device configured to change an irradiating direction of the laser beam guided from the laser oscillator;a moving device operable to move the laser irradiating device; anda control unit operable to control the reflecting device such that when an operating speed of the moving device is changed, a resultant speed of a focus moving speed of the laser beam by movement of the laser irradiating device and a focus moving speed of the laser beam by movement of the reflecting device is equal to a predetermined value.

2. The apparatus according to claim 1 wherein the reflecting device is a reflecting mirror.

3. The apparatus according to claim 1 wherein the control unit is further operable to: change a laser power value of the laser oscillator when the resultant speed becomes less than or equal to a predetermined lower limit speed.

4. The apparatus according to claim 3 wherein the control unit is operable to change the laser power value of the laser operator by reducing the laser power value of the laser oscillator as the resultant speed slows down.

5. The apparatus according to claim 4 wherein the control unit is operable to increase a moving speed of the moving device when a projected laser power value is less than a predetermined lower limit.

6. The apparatus according to claim 1 wherein the reflecting device is configured to rotate to change the irradiating direction of the laser beam guided from the laser oscillator.

7. A laser welding apparatus for performing welding by irradiating a laser beam, the apparatus comprising: a laser oscillator operable to generate a laser beam;a laser irradiating device having a reflecting device configured to change an irradiating direction of the laser beam guided from the laser oscillator;a moving device operable to move the laser irradiating device; anda control unit operable to control the reflecting device such that when an operating speed of the moving device is changed, a moving speed of a laser focus based on movement of the laser irradiating device and movement of the reflecting device is equal to a predetermined value.

8. An apparatus for laser welding, comprising: a laser oscillator for generating a laser beam;a laser irradiating device having a directing device to direct the laser beam at a weld point at a first welding speed;a moving device operable to move the laser irradiating device, the moving device operable to move the weld point at a second welding speed; anda control unit operable to selectively move at least one of the directing device and the head moving device to maintain a resultant speed of the first welding speed and the second welding speed equal to a predetermined value.

9. A method of performing laser welding using a laser irradiating device having a reflecting mirror movable to change an irradiating direction of a laser beam, the method comprising: generating a laser beam;moving the laser irradiating device at an operating speed other than a programmed operating speed; andcontrolling the reflecting mirror such that a resultant speed of a focus moving speed of the laser beam by movement of the laser irradiating device and a focus moving speed of the laser beam by movement of the reflecting mirror is equal to a predetermined resultant speed when the laser irradiating device is operated at the programmed operating speed.

10. The method according to claim 9, further comprising: changing a laser power value of the laser beam when the resultant speed becomes equal to or less than a predetermined lower limit speed.

11. The method according to claim 10, further comprising: increasing the operating speed when the laser power value becomes equal to or lower than a predetermined lower limit according to the change of the laser power value.

12. The method according to claim 9 wherein controlling the reflecting mirror includes: calculating a rotating angular velocity of the reflecting mirror to obtain the focus moving speed using the predetermined resultant speed.

13. The method according to claim 12, further comprising: changing a distance of the laser irradiating device relative to a weld point by changing a position of a condensing distance varying lens located in the laser irradiating device.

14. The method according to claim 9, further comprising: corresponding position data of the condensing distance varying lens to a motion path of the moving device and a rotating angle of the reflecting mirror.

15. The method according to claim 9, further comprising: starting a laser irradiation at a laser irradiating start point; andterminating the laser irradiation when reaching a laser irradiating finish point.

16. The method according to claim 9, further comprising: instructing a rotating speed of the reflecting mirror and the laser power of the laser oscillator depending on an override ratio.

17. The method according to claim 16, further comprising: obtaining the override ratio from external of the laser irradiating device.

18. The method according to claim 17, further comprising: determining whether the reflecting mirror can be rotated at the rotating speed.

19. The method according to claim 18, further comprising: adjusting the laser power value if the rotating speed exceeds a rotatable maximum speed of the reflecting mirror.

20. The method according to claim 19, further comprising: determining whether the adjusted laser power value is less than a predetermined critical value.

21. The method according to claim 20, further comprising: changing the override ratio to be equal to or greater than the predetermined critical value if the adjusted laser power value is less than the predetermined critical value.

22. The method according to claim 19, further comprising: performing an override operation with an adjusted laser power value if the adjusted power value is greater than or equal to the predetermined critical value.