Multi-layer padding welding method

• US 4,491,266 A
• Filed: 11/06/1981
• Issued: 01/01/1985
• Est. Priority Date: 09/10/1980
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Original Assignee: Kabushiki Kaisha Komatsu Seisakusho
• Inventors: Tsujikado, Seiji, Abe, Riichi, Tsuruta, Katsuji
• Primary Examiner(s): Godici, Nicholas P.
• Assistant Examiner(s): Musselman, Jr., P. Weston
• Application Number:
  US06/318,951
• Time in Patent Office: 1,152 Days
• Field of Search: 228/45, 228/225, 228/226, 228/102, 219/124.34, 219/125.1, 219/125.11, 219/124.22, 364/513, 364/477, 901/42
• US Class Current: 228/225
• CPC Class Codes: B23K 9/0216 Seam profiling, e.g. weaving, multilayer
• CPC Class Codes: G05B 19/423 Teaching successive positions by walk-through, i.e. the tool head or end effector being grasped and guided directly, with or without servo-assistance, to follow a path
• CPC Class Codes: G05B 2219/45083 Manipulators, robot
• CPC Class Codes: G05B 2219/45135 Welding
• CPC Class Codes: G05B 2219/50336 Tool, probe offset for curves, surfaces, contouring

Abstract

A method for performing multi-layer welding using a welding robot, in which welding on the second and subsequent layers is carried out by backwardly displacing the position of a torch tip by a preset value.

Claims

1. A multi-layer padding welding method using a welding robot having a body movable along orthogonal axes and having a wrist with two axes of rotation, a torch tip being mounted at the end of said wrist, wherein the positioning of said torch tip is controlled using a predetermined constant as a parameter so as to follow a desired trajectory, said method comprising the steps of:

conducting a teaching operation only for the first layer welding, during which teaching operation the pivotal orientation about said two axes of rotation of said welding robot body is determined for each point in a desired weld trajectory,

and for welding of the second layer onward, calculating for each point in said desired weld trajectory a new position of said welding robot body taking into account a modified length value associated with the separation between the locations of said two axes of rotation of said wrist, the torch tip being displaced in accordance with said calculated value from the desired trajectory.

2. A multi-layer padding welding method using a welding robot having a robot body movable along orthogonal axes, a torch, and a wrist between said robot body and said torch, and wherein said wrist includes two pivoting shafts which pivot in mutually orthogonal directions, and wherein said torch tip may be controlled in accordance with a predetermined constant so as to follow a desired trajectory, said method comprising the steps of:

carrying out a teaching operation in which said torch tip is directed along a desired welding path, and the angular positions of said wrist about said two pivoting shafts, and the position along said orthogonal axes of said robot body are determined for each position along said desired welding path,

calculating from said determined values a set of trajectory positions using a constant obtained by determining a distance value associated with the separation between said two pivoting shafts, and

thereafter carrying out additional layers of said multi-layer padding welding by, at each layer, computing from said calculated set of trajectory positions a new set of trajectory positions for said robot body utilizing a modified constant, thereby displacing the trajectory of said torch tip by an amount established by said modified constant.

3. A multi-layer padding welding method using a welding robot having a welding wire pivotally mounted at the front end of the arm of a welding robot, said arm front end being controllably movable to a point along orthogonal axes, said method comprising the steps of:

obtaining, during a teaching phase, the pivotal orientation of said welding wire and the position of said front end of the welding robot arm for each point in a desired weld trajectory,

determining the position of the tip of the welding wire at each such position on the trajectory, during said teaching phase, with respect to said orthogonal axes, said tip position being relatable by a certain relationship to said obtained position of the front end of said welding robot arm by a length factor,

directing the path of said robot arm during subsequent welding phases by driving, at each point in said trajectory, the welding wire to the same pivotal orientation as obtained during the teaching phase, and by driving the front end of the welding robot arm to a position with respect to said orthogonal axes at which the front end of said arm is related to the welding wire tip position established during said teaching phase by same certain relationship but with said length factor being modified by a constant, whereby by changing only said length factor by a constant on a subsequent welding phase, lap welding along the original welding trajectory, but offset therefrom by a fixed amount, will be obtained.