Method of teaching welding robot

• US 5,898,285 A
• Filed: 02/24/1998
• Issued: 04/27/1999
• Est. Priority Date: 03/11/1997
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Kobayashi, Nobuo, Kaneko, Mitsugu, Nagasawa, Toshiaki, Ohiwa, Hisaya, Bundou, Isao
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US09/028,774
• Time in Patent Office: 427 Days
• Field of Search: 318/568.1, 318/568.11, 318/568.13, 318/568.14, 318/574, 318/576, 219/86.1, 219/86.7, 414/5, 901/42
• US Class Current: 318/568.13
• CPC Class Codes: B23K 11/315 with one electrode moving on a linear path
• CPC Class Codes: B23K 11/317 Equalizing; Balancing devices for electrode holders
• CPC Class Codes: B23K 2101/18 Sheet panels
• 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

Abstract

A welding robot has a gun main body, a stationary electrode tip which is immovable relative to the gun main body, and a movable electrode tip which is mounted on the gun main body and is opened and closed by a pressing source. The gun main body is movable by a driving source in a direction in which both the electrode tips lie opposite to each other. In teaching the welding robot by the movement thereof to each weld spot position of a workpiece, the movable electrode tip is moved in a closing direction relative to the gun main body by the pressing source in a state in which the gun main body is kept stationary at a predetermined position relative to the gun support bracket. The stationary electrode tip is moved in the closing direction by a relative movement of the gun main body relative to the movable electrode tip after the movable electrode tip has come into contact with the workpiece. A position at which the stationary electrode tip contacted the workpiece is detected. This position is stored as teaching data.

Claims

1. A method of teaching a welding robot, said welding robot comprising a spot welding gun which is mounted via a gun support bracket on an operating end of said welding robot, said spot welding gun comprising:

a gun main body;

a stationary electrode tip which is mounted on said gun main body so as to be immovable relative thereto;

a movable electrode tip which is mounted on said gun main body and is operated to open and close by a pressing source, said gun main body being movable by a driving source relative to said gun support bracket in a direction in which both said electrode tips lie opposite to each other, said method comprising the steps of;

in teaching said spot welding gun by the movement thereof to each weld spot position of a workpiece, moving said movable electrode tip at said each weld spot position in a closing direction relative to said gun main body by said pressing source in a state in which said gun main body is kept stationary at a predetermined position relative to said gun support bracket, and moving said stationary electrode tip in a closing direction by a relative movement of said gun main body relative to said movable electrode tip after the movable electrode tip has come into contact with the workpiece;

detecting a position at which said stationary electrode tip contacted the workpiece; and

storing said position as teaching data.

2. A method of teaching a welding robot according to claim 1, wherein, when said movable electrode tip is moved in the closing direction relative to said gun main body, a driving force of said driving source is held to a value which is both necessary and sufficient to support a weight of said gun main body.

3. A method of teaching a welding robot, said welding robot comprising a spot welding gun which is mounted via a gun support bracket on an operating end of said welding robot, said spot welding gun comprising:

a gun main body;

a stationary electrode tip which is mounted on said gun main body so as to be immovable relative thereto;

a movable electrode tip which is mounted on said gun main body and is operated to open and close by a pressing source, said gun main body being movable by a driving source relative to said gun support bracket in a direction in which both said electrode tips lie opposite to each other, said method comprising the steps of;

in teaching said spot welding gun by the movement thereof to each weld spot position of a workpiece, moving said stationary electrode tip at said each weld position, at a predetermined set speed, through movement of said gun main body by means of said driving source in a closing direction in which said stationary electrode tip approaches the workpiece, and moving said movable electrode tip, at a relative speed which is equal to said set speed, relative to said gun main body by said pressing source in a closing direction;

detecting a point of time at which said stationary electrode tip contacted the workpiece;

pressing the workpiece by contacting said movable electrode tip with the workpiece while said stationary electrode tip is held to the position at the point of time of said contact; and

storing the position of said stationary electrode tip at the time of pressing as teaching data.

4. A method of teaching a welding robot according to claim 3, further comprising the steps of:

when said stationary electrode tip is moved to the closing direction, setting an upper limit value of a driving force of said driving source to such a value that the movement of said gun main body is restrained when said stationary electrode tip has slightly contacted the workpiece;

detecting the speed of movement of said gun main body; and

detecting a point of time at which said speed of movement of said gun main body has become zero as said point of time of said contact.

5. A method of teaching a welding robot according to claim 3, further comprising the steps of:

when said stationary electrode tip is moved in the closing direction, detecting a driving load of said driving source; and

detecting a point of time at which said driving load has increased as said point of time of contact.