Briefly described in the article are the structure of the three - roll piercing mill and troubles and failures frequently occurring in the operation thereof.

Introduced in the article are the technical features and equipment structure of the dynamically stable 2-roll horizontal piercing mill as well as its operation results.

This paper analyzes the reasons leading to rolled stock jamming in duo cone type piercing mill on piercing mill adjustment and tool shape etc. and puts forward corresponding preventive measures.