Seamless steel pipe cold processing methods:
①cold rolling ②cold drawing ③spinning
a. Cold rolling and cold drawing are mainly used for: precision, thin-walled, small diameter, abnormal cross-section and high-strength pipes
b. Spinning is mainly used for: the production of large diameter, thin wall or super large diameter, ultra-thin wall steel pipes, and has a tendency to be replaced by welded pipes (steel strip, welding, heat treatment, etc.)
The main process flow of producing seamless steel pipes by cold drawing:
Pipe blank preparation → Cold drawing of steel pipe → Finishing and processing of finished steel pipe → Inspection
Characteristics of seamless steel pipes produced by cold drawing (compared with hot rolling)
①The outer diameter of the steel pipe becomes smaller until capillary tubes can be produced
②Steel pipe wall is thinner
③Steel pipe has higher dimensional accuracy and better surface quality
④The cross-sectional shape of the steel pipe is more complex, and variable cross-section and special-shaped steel pipes can be produced
⑤ Steel pipe performance is superior
⑥High production cost, large tool and mold consumption, low yield rate, small output, and higher environmental protection requirements
Cold drawn tube quality defects and their prevention
⒈ The quality defects of cold-drawn steel pipes mainly include: uneven wall thickness of steel pipes, out-of-tolerance outer diameter, surface cracks, surface straight lines and scratches, etc.
①The uneven wall thickness of cold-drawn steel pipes is related to the wall thickness accuracy of the tube blank, the drawing method, the drawing centerline offset, the hole shape, the deformation process parameters and the lubrication conditions.
a. Improving the wall thickness accuracy of the tube blank is an important prerequisite for improving the wall thickness accuracy of the cold drawn steel pipe.
b. The main purpose of extubation without mandrel is to reduce diameter and deformation
c. The hole shape is an important factor affecting the uneven wall thickness of cold drawn steel pipes.
d. It is also an effective method to ensure the pickling quality of the tube blank, remove the iron oxide scale on its surface, and improve the lubrication quality.
②During the production process, great attention should be paid to the wear and tear of fitting and drafting
③In order to reduce cracks on the surface of the steel pipe after pulling, qualified pipe blanks should be selected, and surface defects of the pipe blanks should be ground. When pickling the pipe blanks, it is necessary to prevent over-pickling to avoid pitting or hydrogen embrittlement, and to To prevent under-pickling and incomplete cleaning of the oxide scale, ensure the annealing quality of the tube blank during use, adopt a reasonable tube drawing method, select appropriate deformation process parameters and tool shape, and strengthen the adjustment and inspection of the drawing center line.
④Improving the pickling quality and lubrication quality of the pipe blank, ensuring the tool hardness, uniformity and surface finish will help reduce the occurrence of straight lines and scratches on the steel pipe.
Post time: Mar-17-2024