Manufacture of hollow structural sections of full cycle starts with preparing strips from coiled hot-rolled steel. Further strip is welded into a single tape and goes to spiral strip accumulator, which provides a constant supply of flat strip to the manufacturing process.
After the accumulator, the flat strip enters the tube mill, where it is pre-formed into a continuous tube with open-seam round by a series of computer-controlled rollers that bend and shape the strip into the proper tube shape.
Strip pre-formed into a continuous tube
Tube with open-seam is passed through welding machine which makes welding of rounded structure with the high-frequency induction.
Tube with open-seam is passing through welding machine
The welder serves to heat the 2-strip edges to a molten state prior to entering the squeeze stand which precisely forges the 2-strip edges under pressure. The tube is then cooled in order to remove the heat induced into the tube during the welding process. The tube is first cooled in air to reduce thermal shock, then is cooled with a water-based coolant just before entering the sizing squaring stands. The combination of the sizing squaring stands, Turk's head and Cambering stands, serve to qualify the tube to its final shape, whether that be round, square or rectangular.
Sizing squaring stands
At the final stage of ready-shaped tubes are cut saw on the set sizes for individual segments. Further note that the product is continuously cooled and during such cutting
Getting final product