| 摘要 |
<p>The invention relates to a nut-positioning pin provided to a lower electrode for projection welding of a nut. A welding device comprises an electrode holder (2) of double-tube structure having a cooling water passage, a guide ring (13) for guiding vertical movement of a coupling rod (7), an air circulation means (m) for preventing sputter entrance, a coupling block (28) made of a magnetic material for preventing the influence of an external magnetism on a magnetism sensor part, and a magnetic shield. The electrode holder can be adequately cooled, the coupling rod can be accurately guided, and entrance of sputter can be prevented. The adverse influence of an external magnetism on the sensor part can be prevented, thereby improving the sensing accuracy.</p> |
