Matters needing attention in the production of precision seamless pipe

1. The thickness of capillary wall shall be uniform and there shall be few internal and external surface defects; External surface polishing and internal hole defect cleaning equipment shall be equipped.

2. Compared with the ordinary cold drawn steel pipe, the cold drawn precision seamless pipe production increases the pickling and re inspection process of hot-rolled capillary, which is mainly to ensure that the outer surface of the capillary is free of folding, cracks and other defects, and eliminate the capillary with folding, serious scribing, pitting and other defects on the inner surface.

3. Generally, the surface finish of the tools used in the production of cold drawn precision seamless steel pipe is required to be Ra0 Above 4, the dimensional accuracy shall reach above H3, and the hardness shall be above HRC70. At the same time, it is required that there shall be no steel sticking on the plug or die in the drawing process.

4. 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 iron oxide scale. Cold drawn precision steel pipes need to be equipped with oxidation free bright annealing furnace equipment.

5. Pickling precision seamless steel pipe is easy to form "black slag" dominated by Fe2O3 and Fe3O4 during sulfuric acid pickling, and form black spots on the surface in subsequent production. Fe2O3 and Fe3O4 are easily soluble in hydrochloric acid. In order to prevent the formation of black spots, 5-10g / L NaCl is added to the acid pool.

6. Resin engine oil shall be selected as lubricant for lubrication. This lubrication is obviously different from phosphating and lubrication (saponification). The drawn steel pipe presents the natural color of iron matrix, with both high finish and beautiful appearance color like cold rolled pipe.