Method of controlling the welding of a three-dimensional structure

• US 7,034,249 B2
• Filed: 06/10/2004
• Issued: 04/25/2006
• Est. Priority Date: 06/12/2003
• Status: Active Grant

• Current Assignee: Meyer Turku Oy (Turku Marine Industry Holding Oy)
• Original Assignee: Kvaerner Masa-Yards Oy
• Inventors: Veikkolainen, Mikko, Gustafsson, Jukka
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US10/866,335
• Publication Number:
  US 20050021170A1
• Time in Patent Office: 684 Days
• Field of Search: 219/124.34, 219/125.1, 901/42
• US Class Current: 219/124.34
• CPC Class Codes: B23K 2101/24 Frameworks
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 37/0235 the guide member forming part of a portal
• CPC Class Codes: B23K 37/0426 Fixtures for other work
• CPC Class Codes: B23K 37/0461 Welding tables
• CPC Class Codes: B23K 9/0026 specially adapted for particular articles or work
• CPC Class Codes: B23K 9/0256 for welding ribs on plates
• CPC Class Codes: B23K 9/032 for three-dimensional seams
• CPC Class Codes: B23K 9/1274 Using non-contact, optical means, e.g. laser means
• CPC Class Codes: B25J 9/1697 Vision controlled systems
• CPC Class Codes: B63B 73/43 Welding, e.g. laser welding
• CPC Class Codes: B63B 73/60 characterised by the use of specific tools or equipment; characterised by automation, e.g. use of robots
• CPC Class Codes: G05B 2219/37555 Camera detects orientation, position workpiece, points of workpiece
• CPC Class Codes: G05B 2219/37571 Camera detecting reflected light from laser
• CPC Class Codes: G05B 2219/45104 Lasrobot, welding robot
• CPC Class Codes: G05B 2219/49362 Tool, probe at constant height to surface during machining

Abstract

A welded structure is formed by arranging multiple pieces on a three-dimensional support base to provide an assembly in accordance with the structure to be welded and making a picture map of the assembly by photographing the assembly. Weld points are identified from the picture map and welding parameters are determined from the picture map. Control data specifying the weld points and welding parameters are supplied to welding equipment that is operable in a three-dimensional X-Y-Z coordinate system. The welding equipment is moved in the X-Y plane on the basis of the picture map and said control data. The welding equipment is moved along the Z-axis on the basis of Z-axis position data that are acquired by repeatedly measuring the Z-axis position of the support base.

Claims

1. A method of forming a welded structure composed of a three-dimensional support base and a plurality of pieces employing welding equipment that is operable in a three-dimensional X-Y-Z coordinate system, said method comprising:

arranging the pieces on the support base to provide an assembly in accordance with the structure to be welded,

photographing the assembly and making a picture map of the assembly,

identifying weld points and determining welding parameters from the picture map,

supplying control data specifying said weld points and welding parameters to the welding equipment,

moving the welding equipment in the X-Y plane on the basis of the picture map and said control data,

repeatedly measuring the Z-axis position of the support base by laser pointing and supplying Z-axis position data to the welding equipment, and

moving the welding equipment along the Z-axis on the basis of the Z-axis position data so as to maintain the welding equipment at a constant Z-axis distance from the support base.

2. A method according to claim 1, wherein the step of laser pointing includes directing three laser pointer beams towards the support base and the method includes analyzing the image of the support base to extract relative locations of the points of incidence of the laser pointer beams on the support base.

3. A method according to claim 2, comprising directing the three laser pointer beams so that they intersect.

4. A method according to claim 2, comprising calculating the Z-axis position of the support base from said relative locations.

5. A method according to claim 1, wherein the welding equipment includes a welding robot that is attached to a carriage for moving the welding robot in the X-Y plane, the method comprises employing a camera to acquire said image, and said camera is attached to the carriage.

6. A method according to claim 1, comprising moving the welding equipment along the Z-axis position in a manner such as to maintain a constant Z-axis distance between the welding equipment and the support base.

7. A method according to claim 1, comprising employing weld groove monitoring to correct errors in positioning of the welding equipment.

8. A method according to claim 7, wherein the weld groove monitoring includes monitoring through a welding arc.

9. A method according to claim 7, wherein the weld groove monitoring includes optical weld groove monitoring.

10. A method according to claim 1, comprising adjusting illumination of the assembly for photographing the assembly.

11. A method according to claim 1, wherein the welding equipment includes a control system, the method comprises supplying the Z-axis position data to the control system, and the control system controls movement of the welding equipment along the Z-axis.

12. A method of forming a welded structure to be used in a watercraft, comprising:

providing a three-dimensional support base,

arranging a plurality of pieces on the support base to provide an assembly in accordance with the structure to be welded,

photographing the assembly and making a picture map of the assembly,

identifying weld points and determining welding parameters from the picture map,

moving a welding robot in an X-Y plane on the basis of the picture map and control data specifying said weld points and welding parameters,

repeatedly measuring the Z-axis position of the support base by laser pointing, and

moving the welding robot along the Z-axis on the basis of the Z-axis position data to maintain the welding robot at a constant distance from the support base.

13. A method according to claim 12, wherein the welding robot addresses a welding location on the support base, the welding location moves about the support base as the welding robot moves in the X-Y plane, and the method comprises repeatedly measuring the Z-axis position of the welding location as the welding location moves about the support base and moving the welding robot along the Z-axis to maintain the welding robot at a constant distance from the welding location.

14. A method according to claim 12, comprising determining a welding track on the support base from the picture map, moving the welding robot in the X-Y plane so that the welding location addressed by the welding robot moves along the welding track, measuring the Z-axis position of the support base at a plurality of locations along the welding track, comparing measured values of the Z-axis positions at said locations respectively, and in the event that a measured value for a given location differs from the measured values for other locations by an amount that exceeds a threshold, calculating a substitute value for the Z-axis position at said given location.

15. A method according to claim 14, wherein the step of calculating a substitute value comprises interpolating or extrapolating from measured values for said other locations.