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Precautions for cold drawn precision seamless steel pipes

by:Mayer     2021-08-22
The cold-drawn precision seamless steel pipe has the characteristics of no oxide layer on the inner and outer walls, no leakage under high pressure, high precision, high finish, no deformation in cold bending, no cracks in flaring and flattening, and anti-rust treatment on the surface. It is mainly used for mechanical structures. , Hydraulic equipment and pneumatic or hydraulic components of automobiles and motorcycles, such as air cylinders or oil cylinders. The basic technological process of cold drawing is: hot rolled capillary—>capillary inspection and grinding—>capillary pickling—>re-inspection after capillary pickling—>cold drawing—>straightening before finishing pass—>pickling, lubrication —>Fine drawing —>Pre-processing of finished products —>Warehousing.  The production needs to pay attention to control:   1, the capillary tube, the capillary tube wall thickness should be uniform, and the internal and external surface defects should be few; external surface polishing and internal hole defect cleaning equipment should be equipped. 2. Re-inspection Compared with ordinary cold-drawn steel pipes, the production of cold-drawn precision seamless pipes adds a hot-rolled capillary pickling re-inspection process, mainly to ensure that the outer surface of the capillary tube is free of defects such as folds and cracks, and eliminates the presence of folds on the inner surface. , Seriously scribed, pitted capillary and other defects.  3. Tools    The surface finish of the tools used in the production of cold drawn precision seamless steel pipes is required to be above Ra0.4, the dimensional accuracy is above H3, and the hardness is required to be above HRC70. At the same time, it is required that the plug or die sticking to steel should not occur during the drawing process.  4. Annealing    Annealing is a very important process in all cold drawn pipe production. The quality of annealing affects both the performance of the steel pipe and the removal of scale. Cold drawn precision steel pipes need to be equipped with non-oxidizing bright annealing furnace equipment.  5. Pickling    In the sulfuric acid pickling process, 'black slag' mainly composed of Fe2O3 and Fe3O4 is easily formed on precision seamless steel pipes, which will form black spots on the surface during subsequent production. Fe2O3 and Fe3O4 are easily soluble in hydrochloric acid. To prevent the formation of dark spots, add 5-10g/l of NaCl to the acid pool. 6. Lubrication should use resin as lubricant. This kind of lubrication is obviously different from phosphating and lubrication (saponification). The drawn steel pipe presents the true color of iron matrix, which has both high smoothness and cold-rolled pipe. The beautiful appearance and color.   The industrial control for the production of cold-drawn precision seamless steel pipes includes mold design, annealing, pickling, lubrication and other conditions. At the same time, it should do a good job in capillary quality inspection and refurbishment.
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