Causes of uneven steel tube wall thickness

1. Uneven spiral wall thickness

Causes: Uneven wall thickness of the piercing machine, unequal inclination of the two rolls, or too small amount of reduction in front of the plug. Uneven wall thickness caused by adjustment reasons, generally distributed spirally along the entire length of the steel pipe. In the rolling process, the centering roller is opened too early, the centering roller is not adjusted properly, and the wall thickness unevenness caused by the jitters of the jack is generally distributed spirally along the entire length of the steel pipe.

2. Uneven wall thickness

Cause: The height adjustment of the mandrel pre-penetration saddle is inappropriate. When the mandrel is pre-penetrated, it touches the capillary on one side, which causes the capillary to drop in temperature too quickly on the contact surface, causing uneven wall thickness and even dent defects.

The gap between the continuous rolling rolls is too small or too large. The center-line deviation of the tube rolling machine. Uneven reduction of single and double racks will cause excessively thick linear symmetrical deviations in the direction of single racks and double racks.

The mortar breaks and the difference between the inner and outer roll gaps will cause a straight deviation of the steel pipe. Improper adjustment of continuous rolling, rolling of piled steel and drawn steel will cause uneven straight wall thickness.

3. Uneven wall thickness at the head and tail

Causes: The cutting slope at the front end of the billet, the bending degree is too large, and the centering hole of the billet is not easy to cause uneven wall thickness of the steel pipe head.

When piercing, the elongation coefficient is too large, the roll speed is too high, and the rolling is unstable. The unstable steel throwing of the piercer is easy to cause uneven thickness of the tail of the capillary tube.