Technical Requirements of Rolls and Reasons for Broken Rolls

1. What Technical Requirements Should the Rolls Meet?

Regardless of hot rolling or cold rolling, the roll is a direct tool to achieve metal deformation during the rolling process. Therefore, the quality requirements of the rolls are strict. Its main quality requirements are strength, hardness, and certain heat resistance.

Roll strength is the most basic quality index. While meeting the strength requirements, it must also have a certain impact on toughness. In order to make the rolls have sufficient strength, it is mainly considered in selecting the roll material and determining a reasonable roll structure and size. Whether the strength is sufficient or not can be determined according to the roll strength calculation.

Hardness usually refers to the hardness of the working surface of the roll, and is also the main index of the roll, which determines the wear resistance of the roll. To some extent, it determines the service life of the rolls. The strength requirements can be met through the selection of materials and some heat treatment of the roll surface.

In addition, when the roll is working under hot rolling conditions, it should also have certain abrasion resistance to protect the accuracy of the product.

1. why is the Roll Broken?

The causes of roll break are as follows:

1) Improper roll cooling. If the cooling water is supplied too early and too fast after the closed water rolling.

2) The roller is not installed correctly, resulting in uneven stress during operation.

3) The roll deformation is too large due to entangled rolls, misfeeding holes, or multiple rolling lines; the rolling temperature is too low, which increases the deformation resistance and the rolling force exceeds the strength limit of the roll.

4) The inherent quality of the roll is not good, the original stress has not been eliminated or there is casting shrinkage; the strength of the roll is low in some places, causing stress concentration.

5) The groove of the roll is deep, the working diameter of the roll is too small, and the strength of the roll is insufficient.

All of the above conditions will lead to roll breaking, but generally, roll breaking is caused by several conditions, and it is a process from quantitative change to qualitative change.

In order to avoid unnecessary roll breaking accidents and extend the service life of the roll, it is necessary to carefully implement the technical operation procedures, strengthen the technical management, analyze the causes from each roll breaking accident in time, and summarize the experience and lessons.