Cold-drawn precision seamless steel pipe with internal and external wall without oxidation layer, to withstand high pressure without leakage, high precision, high finish, cold bending is not deformed, flaring flat no cracks, the surface has been anti-rust treatment and other characteristics, mainly for mechanical structure , Hydraulic equipment and automotive motorcycles pneumatic or hydraulic components, such as cylinders or cylinders. The basic process of cold drawing is: hot-rolled capillary tube -> capillary inspection, grinding -> capillary pickling -> after pickling pickling -> cold drawn -> fine pull straight before -> pickling, lubrication -> fine -> finished product pre - processing -> storage. Production need to pay attention to control: 1, Capillary Capillary wall thickness to be uniform, less inside and outside the surface defects; to configure the external surface polishing and hole defect cleaning equipment. 2, Re-examination Compared with ordinary cold drawn steel pipe, cold drawn precision seamless pipe production increased the hot-rolled capillary pickling re-inspection process, mainly to ensure that the outer surface of the capillary without folding, cracks and other defects, excluding the inner surface of the fold, dumplings and other defects of the capillary. 3, Tools General cold drawn precision seamless steel pipe production tools used in the surface finish requirements Ra0.4 or more, the dimensional accuracy of H3 above, hardness requirements above HRC70. At the same time require the drawing process can not appear head or die sticky steel phenomenon. 4, Annealing Annealing is a very important step in the production of all the cold drawn tubes. The quality of the annealing affects both the performance of the steel pipe and the removal of the oxide scale. Cold drawn precision steel pipe need to be configured without oxidation bright annealing furnace equipment. 5, Pickling Precision seamless steel pipe in the acid pickling process is easy to form Fe2O3, Fe3O4-based "black slag", in the subsequent production of the formation of surface black spots. Fe2O3, Fe3O4 soluble in hydrochloric acid, in order to prevent the formation of dark spots in the acid pool by adding 5-10g / l of NaCl. 6, Lubrication Should use the resin as a lubricant, this lubrication and phosphating plus lubrication (saponification) compared to a significant difference, drawn out of the iron tube showing the true nature of the iron matrix, both high finish and cold-rolled like a beautiful appearance Color. Production of cold drawn precision seamless steel pipe industrial control, including mold design, annealing, pickling, lubrication and other conditions control, and should be in the capillary quality testing, renovation work.

At present, the spiral pipe widely used double-sided submerged arc welding technology, the following talk about the formation of submerged arc welding process and characteristics. Principle of submerged arc welding: Submerged arc welding is the use of arc thermal welding, and welding electrode welding is different: submerged arc welding wire is bare, no paint above, submerged arc welding flux is pre-paved in the welding, submerged arc welding The wire extends into the flux and the arc is burned under flux. Process of submerged arc welding: Welding wire contact with the workpiece, press the start button, the wire and the workpiece power of the moment, the wire back pumping, arc ignition, welding trolley forward, continuous welding wire to maintain the arc in the flux layer under the combustion, under the arc The formation of welding pool. Around the arc, the flux melts to form a void. The void and the molten pool are moving forward, and the molten metal behind the pool solidifies to form a continuous weld. This process is carried out under the flux, so we can not see with the naked eye. It can be seen by means of X-ray photography. As the spiral steel pipe welding technology using submerged arc welding, in addition to this high production efficiency; production of auxiliary time less, saving the time for welding electrodes; welding conditions clean and no splash, saving clean up the time; But also for the spiral pipe plant delivery provides the necessary conditions, making a large amount of spiral steel pipe production time is guaranteed, so it is still widely used.

In recent years, the proportion of seamless steel pipe in China's steel production is growing, because of its wide range of uses, its quality also put forward a higher demand, which seamless steel pipe wall thickness deviation is important for its quality One of the indicators.  In the actual production process, the general existence of the following problems: 1. Deviation in the perforation process. 2. Equipment manufacturing accuracy and structure 3. Installation and adjustment of equipment lines 4. Tube heating process 5. Tube cutting 6. Effect of tool precision 7. Use automatic rolling mill

Large diameter straight seam welded pipe in the factory should do before the mechanical performance test and flattening test and flaring test, and to meet the requirements of the standard requirements. First from the surface to judge, that is, in the appearance of inspection. The appearance of the welded joint inspection is a simple procedure and a wide range of test methods, is an important part of the finished product inspection, mainly to find the weld surface defects and size of the deviation. Generally through the naked eye observation, with standard templates, gauges and magnifying glass and other tools for testing. Pressure test of pressure vessel: pressure vessel, in addition to the sealing test, but also for strength test. Commonly there are two kinds of hydraulic pressure test and air pressure test. They are able to test the weld densities of containers and pipes working under pressure. Pneumatic test is more sensitive and faster than hydrostatic test, and the product is not drained when tested, especially for difficult drainage products. But the risk of testing than the hydraulic test. During the test, the corresponding safety and technical measures must be observed to prevent accidents during the test. Diligence test: the storage of liquid or gas welding containers, the weld is not dense defects, such as penetrating cracks, pores, slag, not penetration and loose tissue, etc., can be used to find the compact test. Physical method of inspection: the physical test method is the use of some physical phenomena for testing or testing methods. Materials or parts of the internal defects of the inspection, are generally used non-destructive testing methods.

The first important way to improve the production of thick-walled seamless pipe machine is to increase the speed of the mill. To improve the speed of the rolling mill, we must first solve the rolling mill frame inertial force and inertia torque balance method and the specific structure, the strength and stiffness of each component and lubrication, cooling, service life and other issues. Increasing the amount of feed and increasing the elongation is another effective measure to increase the production of the pipe mill. To this end, the use of ring-shaped block is the ideal solution, it is conducive to lengthen the rack travel and not too much to increase the diameter of the roll. The third way to improve the production of cold-rolled pipe machine is to improve the effective working coefficient and value of the rolling mill. On the one hand, the requirements of the rolling mill design to be reasonable, high precision manufacturing to reduce maintenance and maintenance downtime. On the other hand to improve the mechanization of the rolling mill, the level of automation to reduce the auxiliary operation time. The third aspect is also a very important direction of development, to achieve the cold-rolled pipe machine non-stop, continuous installation and continuous rolling. The second measure to improve the production of rolling mill is to increase the number of simultaneous rolling pipe. It should be noted that the increase in the number of lines does not increase the throughput of the mill, and the accuracy of the finished pipe will be reduced. It is entirely possible for the intermediate process.