Processing methods commonly used for seamless steel pipes

Main Processing Methods for Seamless Pipes (SMLS):

Forging Method:

Utilizes a swage forging machine to elongate the pipe's end or a section of it, reducing the outer diameter. Common swage forging machines include rotary, connecting rod, and roller types.

Stamping Method:

Employs a tapered core on a punching machine to expand the tube end to the required size and shape.

Roller Method:

Involves placing a core inside the tube and using a roller to press around the outer circumference for round edge processing.

Rolling Method:

Generally does not require a mandrel and is suitable for processing the inner round edge of thick-walled tubes.

Bending Method:

Three commonly used techniques are the expansion method, stamping method, and roller method. The roller method uses 3-4 rollers, with two fixed rollers and one adjustable roller. With a fixed roll pitch, the pipe is bent to the desired shape.

Bulging Method:

Two techniques are used:

One involves placing rubber inside the pipe and using a punch to compress it, causing the pipe to bulge.

The other uses hydraulic bulging, where the pipe is filled with liquid, and the liquid pressure shapes the pipe. This method is optimal for producing corrugated pipes.

Processing Temperatures for Seamless Steel Pipes

Seamless steel pipes are categorized based on processing temperatures into cold working and hot working.

- Hot-Rolled Seamless Steel Pipe:

Heat the round tube billet to a specific temperature.

Perforate the heated billet.

Perform continuous rolling or extrusion.

Strip and size the pipe.

Cool the pipe to form the billet tube.

Straighten the pipe.

Conduct flaw detection experiments.

Mark and store the finished pipe.

- Cold-Drawn Seamless Steel Pipe:

Heat and pierce the round tube billet.

Perform heading and annealing.

Pickle and oil the billet.

Cold roll the billet.

Heat treat and straighten the pipe.

Conduct flaw detection and other procedures.

Mark and store the finished pipe.