Method of welding three-dimensional structure and apparatus for use in such method

• US 20030108234A1
• Filed: 11/25/2002
• Published: 06/12/2003
• Est. Priority Date: 11/26/2001
• Status: Active Grant

• Current Assignee: mitsubishi hitachi power systems, ltd. (Mitsubishi Heavy Industries, Ltd.)
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Takeuchi, Yasushi, Mega, Masahiko, Kitagawa, Tomoaki, Fujita, Ken, Tsunatani, Toshihiko
• Granted Patent: US 7,239,736 B2
• Time in Patent Office: Days
• US Class Current: 382/141
• CPC Class Codes: B23K 26/044 Seam tracking
• CPC Class Codes: B23K 26/24 Seam welding
• CPC Class Codes: B23K 37/00 Auxiliary devices or processes, not specially adapted to a procedure covered by only one of the preceding main groups eye-shields for welders worn on the operator's body or carried in the hand A61F9/00 , i.e. A61F9/02; applicable to metal-working machines other than soldering, welding, or flame-cutting machines B23Q; laser protective screens B23K26/706; protective shields for other welding methods F16P1/06
• CPC Class Codes: B23K 9/1274 Using non-contact, optical means, e.g. laser means

Abstract

When a three-dimensional structure is formed by welding a plurality of members, accurate welding can be performed matching the three-dimensional shape. The teaching data consisting of the three-dimensional position at each of the welding points determined on each of the welding lines at a predetermined spacing on the basis of the design data of the three-dimensional structure is stored in a memory 18. A laser slit light sensor (a laser slit light emitting section 12 and a CD camera 13) is controlled by a total controller 17 via a camera controller 14 to photograph the welding point in order to obtain the image data of the welding point. An image processing apparatus 16 processes the image data to determine the amount of deviation from the design data of welding points. The total controller modify the teaching data on the basis of the amount of deviation from the design data of welding points to establish the modified teaching data and controls a welding head so that it moves according to the modified teaching data.

Claims

1. A method of welding a three-dimensional structure used when forming the three-dimensional structure by combining and connecting a plurality of members by welding along welding lines, comprising a first step in which three-dimensional positions(coordinates) of welding points are determined on each of said welding lines at a predetermined spacing on the basis of the design data of said three-dimensional structure, the teaching data consisting of the three-dimensional positions of said welding points and the normal vectors at the points is established, and the amount of deviation of position from the design data at each welding point is determined from the image obtained by photographing each welding line at each welding point according to said teaching data;

a second step in which the modified teaching data corrected by said amount of deviation of position from the design data is obtained; and

a third step in which welding is performed along said welding line on the basis of said modified teaching data.

2. The method of welding a three-dimensional structure according to claim 1, wherein supplemented teaching data, which is the teaching data consisting of said modified teaching data and welding condition in accordance with the amount of deviation of position from the design data to said modified teaching data is used in said second step, and the welding is performed according to said supplemented teaching data instead of said modified teaching data in said third step.

3. The method of welding a three-dimensional structure according to claim 1, wherein said amount of deviation of position from the design data is determined by light section method in said first step.

4. The method of welding a three-dimensional structure according to claim 1, wherein the amount of deviation of position from the design data in a vertical direction, gap width, and amount of deviation from the designated seam line at each welding point are determined by light section method as the first deviation, the amount of deviation of position from the design data in a horizontal direction is determined by shading method as the second deviation, and said first and second deviation are used as said amount of deviation of position from the design data.

5. The method of welding a three-dimensional structure according to claim 1, wherein said welding points are photographed to obtain welding images during welding and said modified teaching data is further modified according to the welding images in said third step.

6. An apparatus for welding a three-dimensional structure used when forming the three-dimensional structure by combining and connecting a plurality of members by welding along welding lines, wherein the apparatus is provided with a memory means in which are stored the teaching data consisting of three-dimensional positions(coordinates) of welding points determined on each of said welding lines at a predetermined spacing on the basis of the design data of said three-dimensional structure and the normal vectors at the points, a photographing means which is controlled to photograph said welding points in order to obtain the image data thereof according to said teaching data, an image processing means which determines said amount of deviation of position from the design data at each of said welding points by processing said image data, and a control means which establishes modified teaching data by modifying said teaching data according to said amount of deviation of position from the design data;

and said control means controls a welding head so that it moves and welds along said welding line according to said modified teaching data.

7. The apparatus for welding a three-dimensional structure according to claim 6, wherein the welding condition depending on said amount of deviation of position from the design data is stored in said memory means, said control means allows the welding condition depending on said amount of deviation of position from the design data to be added to said modified teaching data to obtain the supplemented teaching data, controls the movement of said welding head according to said supplemented teaching data instead of said modified teaching data, and also controls the output of said welding head and the supply of welding wire.

8. The apparatus for welding a three-dimensional structure according to claim 6, wherein said photographing means has a light emitting section for emitting laser slit light and a CCD camera for receiving the laser slit light so that said image data is obtained by light section method.