The production of cold-drawn seamless pipes should be controlled carefully.


1. Capillaries
Capillary wall thickness should be uniform, internal and external surface defects should be small; external surface polishing and internal hole defect cleaning equipment should be arranged.


2. Review
Compared with the common cold-drawn steel pipe, the hot-rolled capillary pickling process has been added to the production of cold-drawn seamless steel pipe, mainly to ensure that there are no defects such as folding and cracking on the outer surface of the capillary. The surface is excluded from folding and severe marking. Defected tubes, such as pitting.


3. Tools
Usually, the surface roughness of tools used in cold-drawn seamless pipe production is higher than Ra0.4, the dimensional accuracy is higher than H3, and the hardness requirement is higher than HRC70. At the same time, it is required that no tip or die adhesion occurs during the drawing process.


4. Annealing
Annealing is a very important process in all cold-drawn pipe production. The quality of annealing affects not only the performance of steel pipe but also the removal of oxide scale. Non-oxidation bright annealing furnace equipment is needed for cold-drawn steel pipe.


5. pickling
In the acid-free steel pipe pickling process, it is easy to form "black slag" consisting mainly of Fe2O3 and Fe3O4, which forms surface black spots in subsequent production. Fe2O3 and Fe3O4 are easily soluble in hydrochloric acid. 5-10g/l of NaCl is added to the acid bath to prevent the formation of black spots.


6. Lubrication
Resins should be used as lubricants. Compared with phosphating and lubrication (saponification), this lubrication has obvious difference. The drawn steel pipe has the real color of iron matrix, and has high gloss and beautiful appearance, such as cold rolled pipe.