| 摘要 |
PROBLEM TO BE SOLVED: To provide a lower electrode unit having a function for detecting the abnormal setting of a nut and a bolt, which unit can surely detect whether or not a nut has been normally supplied when the nut is welded on a flat plate, etc. in a stationary spot welding machine. SOLUTION: A guide pin 2 is provided on the upper end portion of a cylindrical lower electrode body 1, and a cylinder 3 is provided on the lower end portion of the cylindrical lower electrode body 1. In addition, a guide rod 4 is arranged between the guide pin 2 and the cylinder 3 and further a digital length measuring unit 5 for measuring the descended amount of a cylinder rod 3a during welding is provided below the cylinder 3. When the nut or a bolt has been normally set, the descended amount of the cylinder rod 3a is input by means of a zero point button to the digital length measuring unit 5 as a reference point. Whether the nut or the bolt has been normally set or not is detected by judging whether or not the measured value of the length measuring unit 5 is within the preliminarily set range during welding. COPYRIGHT: (C)2006,JPO&NCIPI
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