| 摘要 |
PROBLEM TO BE SOLVED: To prevent welding failure and reduce a welding time by always starting energization at a stable point and maintaining a proper pressing force even if an air pressure to a cylinder varies due to environmental temperature or the pressing force varies due to abrasion and the like of an electrode, in a resistance welding machine which nips and presses plural welded materials between electrodes with an air cylinder worked by receiving the secondary air pressure being pressure-reduction adjusted by a pressure reducing valve, and welds the welded material by conducting the welding current between the electrodes under the above-mentioned pressing condition and generating the Joule heat. SOLUTION: A secondary pressing air pressure to be supplied to an air cylinder 6 is detected at a welding time, and the time when the detected air pressure is continuously held to an approximate setting pressure, is judged as its stable condition, whereby the energization to electrodes 4 and 10 is started. The squeeze time can vary corresponding to the secondary air pressure, and when the pressing force of the electrodes 4 and 10 against welded materials W1 and W2 becomes the set pressing force, energization is immediately started.
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