Abstract: In the rolling process of the temper mill, the roll surface is always subjected to the huge contact stress, alternating stress and friction. It results in some cracks easily. Under the impact of the complex force, the cracks turn into the core of fatigue. In this way, the stress of the cracks tip increases sharply and leads to crack-propagation. It even results in the roll breakage and brings about production accident in severe cases. Meanwhile, the cracks grow with the rapid releasing of strain wave, which causes the phenomena of acoustic emission(AE). So the acoustic emission technology is adopted to locate the cracks in the roll of temper mill. The advantage of the technology is that cracks are located without point by point scanning and this technology is a high efficiency test and has good real-time performance. According to the “multi-sources” in 3D location of the roll, the information entropy is proposed to calculate the score according to the acoustic emission parameters. Then the composite indicator is obtained to evaluate the normal state of the roll and the range of the interference sources’ composite indicator is confirmed. Interference sources of the roll with cracks are efficiently rejected using this range, therefore the location accuracy of the roll cracks is improved. The experimental data of the normal roll and the roll with cracks in the temper mill of cold rolling in a steel factory is analyzed. The location result is compared with the original result, which shows that the method is effective to detect the location information of the cracks accurately and timely and provide strong support for the safety in production of the roll.

Key words: 3D location, Acoustic emission, Crack in the roll, Information entropy