Quenching and bending of seamless pipes

Quenching and bending of seamless pipes

Seamless pipes are an important type of steel pipe in production and life, and are an important durable steel material among steel pipes. Seamless steel pipes will also encounter bending deformation during use. When the seamless steel pipe is bent and deformed, the seamless steel pipe can continue to be used as long as it can be corrected, otherwise the seamless steel pipe will affect its use. The curvature of seamless steel pipes can also be controlled and should be controlled from the following aspects:

The degree of bending of seamless steel pipes during quenching can be controlled from the following aspects:

(1) Adopt a graded cooling process of outer spraying first and then inner spraying. Because the water spray inside the seamless steel pipe flows from one end of the seamless steel pipe to the other end, the cooling rates of the two ends of the seamless steel pipe are different, causing the seamless steel pipe to bend. Therefore, the external water spray cooling method can be used to cause structural changes on the surface of the seamless steel pipe first, and then the internal water spray cooling method can be used to avoid bending deformation of the seamless steel pipe. The internal water spray is 2~10s later than the external water spray.

(2) Reduce the length of the hanging end of the seamless steel pipe on the runner. Through the reasonable arrangement of the runner and the length control of the seamless steel pipe, controlling the hanging amount of the seamless steel pipe end to ≤600mm can effectively reduce the centrifugal force and the bending degree of the seamless steel pipe end during quenching.

(3) Reasonably control the runner speed.

(4) Control the center of the water quenching wheel. The center deviation of the runner has a great influence on the bending degree of the seamless steel pipe during quenching. After research, the center range of the runner should be controlled within 0-5 mm.

(5) Control the amount and uniformity of internal and external water spray. When quenching and cooling the steel pipe, laminar flow cooling on the outer surface and axial spraying on the inner surface are used. The size and uniformity of the external water spray, the size of the internal water spray, and the alignment of the inner nozzle are also important factors that affect the bending degree of the seamless steel pipe during water quenching.

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