Pressing is carried out with rolls of the pipe rolling mill, and in order for pressing the necessary support, a special mandrel is installed inside the rolled pipe, which has the shape of an artillery project. The production of pipe overlap is in the following order, different from the production of a seamless steel pipe.First of all, barks are coagulated into the pipe. For this purpose, it is heated to red (not to welding heat) and extended through the same funnel as in the production of pipes in the first. Having gone through the funnel, the bar is curtailed into the tube, but does not weld, and one edge of the barns finds on another, creating the preparation for the seam of the overlap. Before curling, the bar’s edges should be scored, since otherwise the seam will turn out too thick. Previously, the mowing of the edges was produced by prison on edge -ost -striped machines, now a cheaper way has been accepted – rolling in a special camp. Further, when the barks are curled into the tube, it enters the furnace, where it heats up to welding heat. The workpiece comes from the furnace directly to the rolls of the rolling mill, in the stream of which the mandrel is pre -installed that takes on the pipe. Valki press the cropped edges to the mandrel and thereby form a welded suture on the lamp. The rolling mill at the moment when the pipe begins to protrude from the rolls.The welded pipe is passed through the camp several times under a row, each time changing the mandrel to another, the diameter of the diameter of the several larger previous.
