Spot welding control method and apparatus using a servo welding gun
First Claim
1. A spot welding control method for controlling a welding gun having a pair of welding electrode tips, at least one of the tips being driven by a respective servo motor, the method comprising the steps of:
- moving the at least one electrode tip relative to a workpiece by driving the servo motor coupled thereto based on an instruction from a main CPU;
detecting both an actual position of the at least one electrode tip and an actual electric current of the servo motor; and
determining, based on the detected values of the actual position of the at least one electrode tip and the actual current, whether an abnormal welding condition exists.
1 Assignment
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Accused Products
Abstract
A spot welding method and apparatus having electrode tips one of which is driven by a servo motor. In the method and apparatus, it is determined whether or not an abnormal condition occurs. The abnormal condition includes (a) squeezing some obstacle between the electrode tip and a workpiece, (b) a temperature adhesion of the electrode tips with the workpiece, (c) uneven pressurizing of the workpiece by the electrode tips, (d) a weld nugget dispersion, and (e) a too large electric resistance between the electrode tips and the workpiece. When such abnormal condition is detected, some counter measure is taken to prevent or decrease the abnormal condition.
42 Citations
22 Claims
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1. A spot welding control method for controlling a welding gun having a pair of welding electrode tips, at least one of the tips being driven by a respective servo motor, the method comprising the steps of:
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moving the at least one electrode tip relative to a workpiece by driving the servo motor coupled thereto based on an instruction from a main CPU; detecting both an actual position of the at least one electrode tip and an actual electric current of the servo motor; and determining, based on the detected values of the actual position of the at least one electrode tip and the actual current, whether an abnormal welding condition exists. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A spot welding control apparatus using a servo welding gun comprising:
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a welding gun including a pair of electrode tips, at least one of the electrode tips being driven by a servo motor; an encoder coupled to said servo motor to detect an actual position of said at least one electrode tip; an electric current detecting sensor electrically connected to said servo motor for detecting an actual electric current of said servo motor; and an abnormal condition occurrence determining means for determining, based on values detected by both the encoder and the electric current detecting sensor, whether an abnormal welding condition exists. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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Specification