Kherson pipe steel seamless cold-smoked, hot-smoked steel st20, st45 6-630 mm (Metallobaza) delivery, cutting

Steel pipes are divided into thin-walled and thick-walled depending on the ratio of diameter to wall thickness (d / s). Thin-walled products include products with outer diameters less than 20 mm and a wall thickness of 1.5 mm, and with a d / s ratio in the range of 12.5-40. Thick-walled products have a d/s ratio of 6 to 12.5. In everyday life and in production, we mainly encounter universal thin-walled products, thick-walled modifications are used in those industries where very high working pressures (hundreds of atmospheres or tens of MPa) are used. The difference between hot and cold rolling Hot deformation is carried out on a workpiece heated to a temperature above 1000 ° C. During cold rolling, the workpiece is not heated. Cold rolling requires more effort, more expensive working tools, the degree of workpiece compression/drawing is less with this method. In addition, after rolling, there are more stresses in the metal and a greater likelihood of defects. Therefore, hot rolling is much more often used. But thin-walled pipes with high requirements for geometric dimensions (wall thickness) are made by cold rolling. Pipes are made from round blanks - slabs. Sleeve unrolling The very first operation is the flashing of a hot billet into a round hollow sleeve. During hot rolling, the workpiece is usually pierced immediately after leaving the slab, before it has had time to cool down. The workpiece is obtained with dimensions close to the dimensions of the finished product. Then the billet is heated in a special furnace and the sleeve is rolled into a thin-walled billet with precise dimensions, then calibrated and the final dimensions of the pipe are obtained. Technological scheme for the manufacture of seamless hot-rolled pipes on a more productive pipe-rolling unit with an automatic mill: Heating of a round billet in an annular rotary hearth furnace. The firmware of the workpiece on the piercing mill - a sleeve with thick walls is obtained. Rolling a sleeve on an automatic mill - a tube with walls with different thicknesses is obtained. Two mills are usually installed to ensure the continuous operation of the complex. Heating the workpiece in the furnace. Rolling out the product on a rolling mill (rilling mill) - the wall thickness variation along the entire length of the product disappears. Calibration of a hot sleeve in a sizing mill. Cooling. Cold straightening in a kos roll mill. Line with continuous mill A more productive and modern method is piercing blanks on a continuous line with 8-9 mills. The productivity and assortment of finished products with this method are maximum. The blanks are cut, heated, the piercing of the sleeve with this method takes place on roll-type mills. Rolling is performed on long mandrels on a number of successively installed stands with gradually decreasing caliber sizes. The mandrels are removed and cooled. With this method, equipment for screw rolling is sometimes used. Pipes are heated and calibrated, rolled out, and cut. It is necessary to constantly monitor the wear of the mandrels and the accuracy of setting all the stands - otherwise there is a high risk of obtaining products with different wall thicknesses. If it is necessary to obtain pipes of small diameter with thin walls, a reduction operation is performed - compression in a large number of successively arranged stands to the required dimensions. Rimless technique There is also such a technique - economical, relatively simple. Many successive calibration and reduction mills are used. On each mill, the section and wall thickness of the pipe is reduced by a small thickness, the tension of the workpieces on each mill is relatively small. The disadvantage of this method of processing blanks is a high risk of obtaining finished products with different wall thicknesses. More progressive is the mandrelless reduction-stretching equipment, which makes it possible to obtain good quality products. A characteristic feature of hot-formed pipes is the absence of a seam. It is its absence that ensures maximum reliability and tightness of pipelines. In some cases, the absence of a seam also has an aesthetic value. A feature of hot-formed products is the optimal ratio of hardness and viscosity, which ensures high structural reliability, resistance to crushing, bending, and twisting. It is these pipes that are used in the installation of critical structures in construction. Areas of application of seamless hot-rolled products It is impossible to imagine our life without large and small pipelines. Pipes surround us from all sides: gas pipelines, heating systems, water supply, sewerage, ventilation, chimneys - all provide us with a comfortable civilized life. The farther into civilization, the more pipes surround us. Seamless steel pipes are indispensable in solving complex industrial and technical problems that involve a large load on the product and the inadmissibility of the slightest leaks. This is very important, for example, under the condition of strong constant pressure in the pipe or under the condition of