| 摘要 |
Apparatus for reducing the diameter, rounding or straightening of pipe or tubing by rolling comprising a plurality of cylindrical rollers arranged in a parallel-cylindrical array through which the pipe or tubing is passed, the rollers being skewed to displace their central contact zones radially inwards bringing them into forceful contact with the external surface of the pipe or tubing, and being rotated to cause the central contact zones to describe helical paths along the external surface of the pipe or tubing. Thereby to progressively apply locally to the whole of the external surface of the pipe or tubing a compressive force in excess of the yield strength of its material, causing the pipe or tubing to adopt a set at a smaller diameter.
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