Laser welding apparatus employing a tilting mechanism and seam follower

• US 5,925,268 A
• Filed: 07/09/1996
• Issued: 07/20/1999
• Est. Priority Date: 06/06/1996
• Status: Expired due to Fees

• Current Assignee: En-Gauge, Inc.
• Original Assignee: En-Gauge, Inc.
• Inventors: Britnell, James W.
• Primary Examiner(s): MILLS, GREGORY L
• Application Number:
  US08/677,092
• Time in Patent Office: 1,106 Days
• Field of Search: 219/121.6, 219/121.63, 219/121.64, 219/121.67, 219/121.76, 219/121.78, 219/121.79, 219/121.8, 219/121.81, 219/121.82, 219/121.83
• US Class Current: 219/121.63
• CPC Class Codes: B23K 2101/185 Tailored blanks
• CPC Class Codes: B23K 2103/04 Steel or steel alloys
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/044 Seam tracking
• CPC Class Codes: B23K 26/0608 in the same heat affected zone [HAZ] B23K26/0613, B23K26/0619 take precedence
• CPC Class Codes: B23K 26/067 Dividing the beam into multiple beams, e.g. multifocusing
• CPC Class Codes: B23K 26/08 Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/0884 in at least in three axial directions, e.g. manipulators, robots

Abstract

In general, the present invention pertains to an apparatus and control system for working sheet material employs a tilting mechanism which automatically tilts a head about a theoretical point disposed upon the sheet material. In another aspect of the present invention, the head is defined as a laser head and the pivot point corresponds with the laser beam focal point. A further aspect of the present invention provides a seam tracking device and control system which automatically adjust a welding head height relative to the sheet material as a datum rather than relative to a gantry or other structure supporting the welding head. In yet another aspect of the present invention, an optical seam tracking device is employed to automatically tilt the welding head along differing rotational planes. In still another aspect of the present invention, various axial slides are employed in combination with a gantry. A further aspect of the present invention uses a seam tracking device and microprocessor to track a welding seam and move a welding head predetermined amounts due to sensed pre-weld gap widths. Another aspect of the present invention uses an automated tilting mechanism for creating a tailored blank butt weld between dissimilar materials. A method of operating the present invention is also provided.

Claims

1. An apparatus for working material pieces comprising:

a laser head operably projecting a laser beam having a focal point by way of a direct path between said laser head and said material pieces, said laser beam operably modifying said material pieces;

a tilting mechanism being coupled to said laser head such that said laser head is tilted about said focal point along a first plane;

a second tilting mechanism causing said laser head to tilt about said focal point along a second plane substantially perpendicular to said first plane wherein all of said first tilting mechanism tilts along said second plane corresponding to movement of a portion of said second tilting mechanism; and

a seam tracking device continuously sensing the positioning of a seam, said laser head substantially following said seam tracking device along said seam.

2. The apparatus of claim 1 further comprising:

a first plate selectively movable in a vertical direction and a horizontal direction proximate said laser head;

a driving bearing device of said second tilting mechanism being affixed to said first plate;

a driven bearing device of said second tilting mechanism being movably engaged to said driving bearing device;

an automatically controlled actuator causing relative movement of said bearing devices;

a second plate being affixed to said driven bearing device; and

a driving bearing device of said first tilting mechanism being affixed to said second plate.

3. The apparatus of claim 2 further comprising a slave tilting mechanism having a driving bearing device affixed to said first plate and having a driven bearing device affixed to said second plate, said slave tilting mechanism being disposed on a substantially opposite side of said laser head from said second tilting mechanism, said slave and second tilting mechanism being oriented substantially parallel to each other and perpendicular to said first tilting mechanism.

4. The apparatus of claim 1 further comprising:

a U axis substantially horizontal slide being coupled to said tilting mechanism, said U axis slide providing adjustment for centering said laser beam along said U axis; and

a T axis substantially horizontal slide being coupled to said tilting mechanism and said U axis slide, said T axis slide providing adjustment substantially perpendicular to said U axis for centering said laser beam along said T axis.

5. The apparatus of claim 4 further comprising a Z axis substantially vertical slide adjustably moving said laser head in a vertical direction for focusing said laser beam, said Z axis slide being coupled to said tilting mechanism.

6. The apparatus of claim 1 wherein said tilting mechanism includes:

a first bearing device being coupled to said laser head;

a second bearing device engaging with said first bearing device, said first bearing device selectively moving in relation to said second bearing device; and

said first bearing device having a partially circular engagement surface with a theoretical radius substantially the same as a focal length of said laser beam.

7. The apparatus of claim 6 further comprising:

a set of teeth being disposed upon said first bearing device, crests of said teeth defining said theoretical radius;

a screw gear being disposed within said second bearing device for meshed engagement with said set of teeth; and

an electromagnetic actuator operably driving said screw gear which rotates said first bearing device.

8. The apparatus of claim 1 wherein said laser beam welds said material pieces together in a butt welding manner, said weld is created substantially at said focal point.

9. The apparatus of claim 8 wherein said laser head is tilted such that said material pieces are welded together even if a pre-weld gap dimension greater than 10 percent of a thickness of one of said material pieces is present between adjacent edges of said material pieces.

10. The apparatus of claim 1 further comprising a microprocessor causing said tilting mechanism to tilt said laser head in relation to said material pieces upon receiving an appropriate signal from said seam tracking device.

11. The apparatus of claim 10 wherein said appropriate signal is output from said seam tracking device when a seam gap width value greater than 10 percent of a thickness of one of said material pieces is sensed.

12. The apparatus of claim 1 wherein said laser head is part of a Yag laser having a fiberoptic cable coupling said laser head to a laser light source, said laser beam moves relative to said material pieces free of rotatable mirrors.

13. The apparatus of claim 1 wherein said laser beam cuts said material pieces.

14. The apparatus of claim 1 wherein said seam tracking device includes a light pattern emitter and an optical sensor.

15. An apparatus for working material pieces comprising:

a laser head operably projecting a laser beam having a focal point by way of a direct path between said laser head and said material pieces, said laser beam operably modifying said material pieces;

a tilting mechanism being coupled to said laser head such that said laser head is tilted about said focal point alone a first plane; and

a seam tracking device continuously sensing the positioning of a seam, said laser head substantially following said seam tracking device along said seam;

a gantry having a movable bridge proximate said laser head;

a motor-driven rotatable carousel being coupled to said bridge by a rotary bearing; and

a motor-driven Z axis substantially vertical slide being coupled to said carousel;

said Z axis slide serving to maintain a focal length of said laser beam as said bridge moves in relation to said material pieces.