| 摘要 |
PROBLEM TO BE SOLVED: To automatically set the axis of a servo type spot welding gun to the reference position, and to automatically perform the correction to the wear of a tip. SOLUTION: Until the estimated disturbance load reaches a first threshold, a movable side welding tip of a welding gun is pressed against a fixed side welding tip (a1-a4). When the estimated disturbance load reaches the first threshold, the movable side welding tip is driven in the direction in which both tips are separated from each other until the estimated disturbance load reaches a second threshold smaller than the first threshold (a5-a9). The setting of the position of the axis of the movable side welding tip when reaching the second threshold is changed as the reference position, and updated and stored (a10). The first threshold is larger than the friction while the second threshold is substantially the friction. The reference position is obtained by a similar method even when the welding tip is worn, and updated. The reference position can be automatically obtained, and even when the tip is worn, the reference position can be obtained in that condition, and the position can be controlled at the constantly taught command position.
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