Cold-drawn precision seamless pipe is a kind of high-precision seamless steel pipe material processed by cold-drawing or hot-rolling. Due to the advantages of no oxide layer on the inner and outer walls of the precision steel tube, no leakage under high pressure, high precision, high finish, no deformation after cold bending, no flaring, no cracks in flattening, etc.Therefore, it is mainly used to produce products for pneumatic or hydraulic components, such as cylinders or oil cylinders.
The main application of precision cold drawn seamless tube
Used in hydraulic system piping, automobile manufacturing piping, military industry, engineering machinery, railway locomotives, aerospace, ships, injection molding machines, die-casting machines, machine tools, diesel engines, petrochemicals, power stations, boiler equipment and other industries.
Steel pipe cold drawing process
Generally, ordinary cold-drawn steel pipes are used as blanks to produce cold-drawn precision seamless steel pipes through fine drawing passes. In order to ensure the quality of precision steel pipes, the production process needs to be adjusted according to the existing production conditions
Hot-rolled capillary → inspection and grinding of capillary → pickling of capillary → re-inspection after pickling of capillary → cold drawing (intermediate annealing, pickling → straightening before fine drawing → pickling, lubrication → fine drawing → pre-treatment of finished product → Storage
The drawing passes before fine drawing of cold-drawn precision tubes are still designed according to the deformation process of ordinary pipes, and the drawing passes of fine drawing adopt the drawing process with a small amount of deformation
Features of cold drawn precision seamless pipe
1. The outer diameter is smaller.
2. High precision and small batch production
3. The cold drawn finished product has high precision and good surface quality.
4. The cross-sectional area of the steel pipe is more complicated.
5. The performance of the steel pipe is better and the metal is denser.
Precautions for the production of cold drawn precision seamless pipes
1. Capillary: Its wall thickness also needs to be uniform, and there are few defects on the inner and outer surfaces. It is also necessary to configure the polishing of the outer surface and the internal control defect cleaning equipment.
2. Re-inspection: If compared with ordinary cold-drawn seamless steel pipes, its production will increase the pickling re-inspection process of hot-rolled capillaries, so as to ensure that the outer surface of capillaries is not folded, cracked and other defects.It is also necessary to exclude some defective capillaries such as folds, severe scribes, and pockmarks on the inner surface.
3. Tools: Generally, in the production of cold-drawn seamless steel pipes, the surface finish of the tools to be used has certain requirements, generally above Ra0.4, the dimensional accuracy is above H3, and the hardness requirements also need to meet certain requirements. At the same time, it is also required that in the process of drawing, the situation that the plug or the die sticks to the steel cannot be produced.
4. Annealing: In the production of all cold drawn pipes, this is also a very important process.The quality of it will affect the performance of the steel pipe, and it will also affect the removal of the iron oxide scale. It also needs to be equipped with non-oxidative bright annealing furnace equipment.
5. Pickling:In the process of sulfuric acid pickling, the precision seamless steel pipe is prone to form "black slag" mainly composed of Fe203 and Fe304, which will form black spots on the surface in the subsequent production. Fe203 and Fe304 are easily soluble in hydrochloric acid. In order to prevent the formation of black spots on soil, add 5-10g/1 NaCl to the acid pool.
6. Lubrication:Resin should be used as lubricant, which is obviously different from phosphating and lubrication (saponification).The drawn steel pipe presents the true color of the iron matrix, which has both high smoothness and the beautiful appearance of cold-rolled pipe clothing.
The industrial control of the production of cold-drawn precision seamless steel pipes includes the control of mold design, annealing, pickling, lubrication and other conditions. At the same time, the quality inspection and repair of the capillary should be done well.
The main application of precision cold drawn seamless tube
Used in hydraulic system piping, automobile manufacturing piping, military industry, engineering machinery, railway locomotives, aerospace, ships, injection molding machines, die-casting machines, machine tools, diesel engines, petrochemicals, power stations, boiler equipment and other industries.
Steel pipe cold drawing process
Generally, ordinary cold-drawn steel pipes are used as blanks to produce cold-drawn precision seamless steel pipes through fine drawing passes. In order to ensure the quality of precision steel pipes, the production process needs to be adjusted according to the existing production conditions
Hot-rolled capillary → inspection and grinding of capillary → pickling of capillary → re-inspection after pickling of capillary → cold drawing (intermediate annealing, pickling → straightening before fine drawing → pickling, lubrication → fine drawing → pre-treatment of finished product → Storage
The drawing passes before fine drawing of cold-drawn precision tubes are still designed according to the deformation process of ordinary pipes, and the drawing passes of fine drawing adopt the drawing process with a small amount of deformation
Features of cold drawn precision seamless pipe
1. The outer diameter is smaller.
2. High precision and small batch production
3. The cold drawn finished product has high precision and good surface quality.
4. The cross-sectional area of the steel pipe is more complicated.
5. The performance of the steel pipe is better and the metal is denser.
Precautions for the production of cold drawn precision seamless pipes
1. Capillary: Its wall thickness also needs to be uniform, and there are few defects on the inner and outer surfaces. It is also necessary to configure the polishing of the outer surface and the internal control defect cleaning equipment.
2. Re-inspection: If compared with ordinary cold-drawn seamless steel pipes, its production will increase the pickling re-inspection process of hot-rolled capillaries, so as to ensure that the outer surface of capillaries is not folded, cracked and other defects.It is also necessary to exclude some defective capillaries such as folds, severe scribes, and pockmarks on the inner surface.
3. Tools: Generally, in the production of cold-drawn seamless steel pipes, the surface finish of the tools to be used has certain requirements, generally above Ra0.4, the dimensional accuracy is above H3, and the hardness requirements also need to meet certain requirements. At the same time, it is also required that in the process of drawing, the situation that the plug or the die sticks to the steel cannot be produced.
4. Annealing: In the production of all cold drawn pipes, this is also a very important process.The quality of it will affect the performance of the steel pipe, and it will also affect the removal of the iron oxide scale. It also needs to be equipped with non-oxidative bright annealing furnace equipment.
5. Pickling:In the process of sulfuric acid pickling, the precision seamless steel pipe is prone to form "black slag" mainly composed of Fe203 and Fe304, which will form black spots on the surface in the subsequent production. Fe203 and Fe304 are easily soluble in hydrochloric acid. In order to prevent the formation of black spots on soil, add 5-10g/1 NaCl to the acid pool.
6. Lubrication:Resin should be used as lubricant, which is obviously different from phosphating and lubrication (saponification).The drawn steel pipe presents the true color of the iron matrix, which has both high smoothness and the beautiful appearance of cold-rolled pipe clothing.
The industrial control of the production of cold-drawn precision seamless steel pipes includes the control of mold design, annealing, pickling, lubrication and other conditions. At the same time, the quality inspection and repair of the capillary should be done well.
