[AT] OT butt welding was tractor hauling truck

[James Peck]

The steel mill sheared the leading and trailing strip edges separately at the entrance end shear. It brought the sheared edges together at the entrance  end. The welder clamped each strip and pressed the strip ends together. Resistance welding  usually has a force parameter. Then the semiconductors gate on for a period. After the current asses through and is turned off, the clamping forces is maintained utile the weld cools some. The strip is then unclaimed and advances to the exit end shear where the weld is cut out.

Dennis Johnson AT List Member (moscowengnr at outlook.com); So what is the process they use??  Do they place a coil around the rails, heat, and then press them together??

James AT List Member (jamesgpeck at hotmail.com); Is the welding supply using semiconductors to regulate the welding current? The steel mill used water cooled ignitron tubes to butt weld the leading edge of the steel strip being cold rolled to the tail of  last piece thru.

Howard Pletcher AT List Member AT List Member (hrpletch at gmail.com); For reference, I recently had a tour of the Steel Dynamics railroad rail welding facility where they weld shorter segments into 1/4 mile long rails. They apply 1000 amps for about 2 seconds to fuse the rails together.   It would take something larger to handle 48,000 amps.