A steam dryer weighting 100 metric tons is used to dry the copper concentrate. It is in the fourth floor of the building. Soon after starting the production, the operators experienced disturbing vibration is the control room. The computer screens were shaking, and it was difficult to read them. The dryer was obviously the source of the excessive vibration. It has two riding rings, which rotate slowly on support rolls. The lower riding ring developed dents at equal distances. The repetition of these dents meeting the support rolls could possibly cause the vibration. Slowly the dents on the ring developed deeper and higher vibration was induced on the floor. Something had to be done to decrease the vibration level. It was concluded that the high vibration was caused by the dents on the ring. Therefore, a decision was made to install a grinding tool on top of the dryer. As the dryer drum rotates, the tool would grind off the variations in the ring diameter. After implementing this solution, the vibration levels first decreased, but after a few months started to increase and the dents appeared on the ring surface again. Vibration animation was then needed to solve the problem.

Takeaways

1. Learn, how to create a structure with multiple substructures
2.  Learn, how to perform the necessary measurements to understand, how the structure moves at different locations.
3. Learn to understand the effect of structure geometrics.
4. Learn, why it is important to verify the information provided.

Veli Lumme started his career more than 40 years ago as an NDT operator. After graduation in Helsinki University of Technology he continued with vibration analysis and related technologies with an extensive interest in machine diagnostics. Several patents related to the use of artificial intelligence in diagnosis have been granted for him.