Metal pipes are made by rolling, welding (or soldered), pressing, drawing, and a combination of these methods, as well as extract from the molten metal and casting. It should be borne in mind that the tubular products turns out not only round, but fitting, as well as a variable cross-section diameter and wall thickness. Metallurgical plants producing pipes from carbon, alloy and high alloy steels, nonferrous metals and alloys of complex composition, bi-metal pipes, etc. Consider the most common methods of production of seamless and welded tubes, obtained using the methods of metal in a plastic condition. Production of seamless pipes hot rolling seamless pipe the manufacture of the first basic operation is flashing round ingot or billet in the sleeve, ie, getting a thick-walled tube. Characteristically, making a hollow sleeve is a very responsible operation that ultimately determines the quality of finished products and the performance of rolling equipment. Firmware harvesting usually is performed in mills, which by design is divided into roll (with obliquely positioned rollers), and disk mills with mushroom rolls. Follow-up sleeves rolled into a tube the required diameter and wall thickness can be performed on automatic mill, the mill pilgrim rolling on a continuous or triple roll mill.
Consider the main features of the receiving tube in these ways. Rolling mills are on automatic seamless pipes diameter of 57-426 mm and wall thickness of 3-30 mm. This method is most common. There is a layout of the equipment automatically mill, and tufted with two automatic one cage for the manufacture of pipes diameter of 140-426 mm. The initial product in this case, use the blank round, obtained by rolling in heavy-and trubozagotovochnyh mills. Workpiece diameter pipes are usually little different from the diameter of the finished pipe. Before rolling the metal is heated in the reheat furnaces or furnaces with a rotating circular hearth. The heated billet after centering the front end of a pneumatic tsentrovatelem for reduction in the flash tube and gage improve the capture of metal rollers comes to piercing mill.
When the firmware receives a blank 2-3.5 times the hood. The maximum value extraction does not exceed 4,5-4,8. Post-processing is performed on an automatic sleeve camp, which is a non-reversible stands duo, in rolls which are arranged sequentially around the gauges. The task of the metal in the rolls in the caliber arbor set, fixed on a long rod so that the gap between sending and gauge determines the thickness of the walls of the rolled tube. The deformation of the metal in this case occurs between the rollers and mandrel, with the addition of thinning the wall has been some reduction in external diameter of the pipe. Since rolling on a round mandrel in a single pass does not provide a uniform deformation of the tube wall on the perimeter, then have to give two and sometimes three passes with the rotation of the tube after each pass through 90 . Hood in one pass, usually no more than 1.4-1.6, and the total may be 1.5-2.1.