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, cold bending no deformation, flaring and flattening no cracks, and the surface has been treated as rust prevention, etc. It is mainly used in mechanical structure, hydraulic equipment and pneumatic or hydraulic components of automobiles and motorcycles, such as cylinders or cylinders.
The basic process flow of cold drawing is: hot rolled tube – > tube inspection, grinding – > tube pickling – > Tube re-inspection after pickling – > Cold drawing – > Straightening before finishing drawing pass – > pickling, lubrication – > finishing drawing – > pre-finished product treatment – > storage.
Production needs attention control:
1. Capillary
The capillary wall thickness should be uniform and the internal and external surface defects should be less. External surface polishing and internal hole defect cleaning equipment should be equipped.
2. Recheck
Compared with ordinary cold-drawn steel pipes, the cold-drawn precision seamless pipe production has increased the hot-rolled tube pickling reinspection process, mainly to ensure that the outer surface of the tube has no folding, cracks and other defects, and to exclude the tube with folded, severely marked, pocked and other defects on the inner surface.
3. Tools
Generally, 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 steel sticking of the top or die cannot occur during the drawing process.
4. Annealing
Annealing is a very important process in all cold-drawn pipe production, and the quality of annealing affects not only the performance of the steel pipe but also the removal of the oxide sheet. Cold-drawn precision steel pipes need to be equipped with non-oxidizing bright annealing furnace equipment.
5. Pickling
Precision seamless steel pipe in the sulfuric acid pickling process is easy to form Fe2O3, Fe3O4-based “black slag”, in the subsequent production to form surface black spots. Fe2O3 and Fe3O4 are easily soluble in hydrochloric acid, and 5-10g/l of NaCl is added to the acid pool to prevent the formation of dark spots.
6. Lubrication
Resin should be used as a lubricant, this lubrication and phosphating lubrication (saponification) compared with the obvious difference, the extracted steel pipe shows the natural color of the iron matrix, both high finish and cold rolled pipe beautiful appearance color.
The industrial control of the production of cold-drawn precision seamless steel pipe includes mold design, annealing, pickling, lubrication and other conditions control, and should do a good job in capillary quality detection and renovation.
