| 摘要 |
A cylindrical wheel rim blank has a longitudinal seam defined by a pair of longitudinal edge portions each of which is clamped between upper and lower jaws of a respective clamping assembly. The two clamping assemblies are urged laterally together to press the two longitudinal edge portions together, and welding current is introduced at the seam through the lower jaws to effect the weld. The upper jaws are at the bottom of cantilevered horn members around which the rim blank is mounted. The lower jaws are urged upwardly toward the cantilevered upper jaws to effect the clamping function. Structure is provided to equalize the clamping pressure exerted against the upper jaw along the length thereof and, if desired, to introduce a bias into the upward pressure exerted through the lower jaw. There is a mechanism to provide different, predetermined spacings between the clamping assemblies as different steps in the operation. Circuitry is provided to produce a reversing, pulsating DC welding current.
|
