Tandem cold mill: Precision work at its finest
To meet this demanding target, the existing cold rolling mill needed a comprehensive upgrade: The 4-stand tandem mill was expanded by the integration of a fifth stand on the mill’s entry side.
In order to be prepared as much as possible prior to the scheduled revamp shutdown, the new mill stand was assembled and pre-commissioned in a pre-assembly pit, next to the TCM during ongoing operation. In parallel, the foundation for the new mill stand was prepared in the oil cellar underneath the entry of the TCM. At the beginning of the shutdown, the mill’s entry equipment was disassembled and the ceiling of the cellar was removed by cutting in order to provide access to the new foundation. Last, the complete new “Mill Stand No. 0” with a total weight of 360 t was skidded to its final position. For that purpose, the mill stand was assembled on a special base-plate unit which was connected to the lifting beams of the skidding system.
Due to the additional mill stand, the maximum thickness of the incoming strip can be increased from 4.8 to 6.0 mm. In addition, the maximum rolling speed was increased to 1,300 meters per minute. Further modules were added or enhanced to cope with the expanded product range and increased output.
Pickling line: A revamp strategy that paid off
The expansion solution also included the pickling line which is linked to the tandem mill. The measures comprised upgrades and replacements of existing core modules. The revamp activities mainly focused on the coil preparation station, entry flattener and entry flying shear, entry and exit looper, new bridle roll unit as well as drives for bridle roll units. Furthermore, the existing hydraulic system was modified and adapted to the new demands. A phased revamp strategy was developed by the SMS specialists which included three individual shutdowns lasting four, five and finally thirty days. The subsequent hot commissioning was completed as scheduled and demonstrates successful planning and execution of the order.
Frank Lettau, SMS group Project Manager in charge of the PL-TCM revamp, explains the revamp strategy: “Different to the TCM area, no pre-assemblies and preparation close to the Pickling Line were possible ahead of the main shutdown due to limited space. In consequence, the first 10 days of the main shutdown were mainly used for disassembling of equipment, removal of existing and pouring of new foundations. Coordination of the various job disciplines as well as of the lifting and transportation equipment was a major the most important task during that time.”
Detailed scheduling and extensive progress controlling was the key to success. ArcelorMittal Vega prepared an overall master time schedule which considered the activities of each contractor. A meeting with all contractors was held twice daily to report on progress and identify countermeasures to prevent potential delays. SMS established a strong site team supported by mechanical and electrical engineers that was available 24/7 during the main shutdown. With this setup, SMS provided ArcelorMittal and its contractors with the full support necessary to fulfill the very ambitious master plan.
Next steps
Recently, ArcelorMittal signed acceptance for the project. Christopher Weber, Technical Manager for the project draws his conclusion: "The conversion of the PL-TCM was technically highly complex, with a very ambitious shutdown schedule at the same time. I am therefore very proud of the SMS team of specialists and what has been achieved together with the customer.”
The further portions of the ArcelorMittal expansion project will be completed this year. A new universal annealing and hot-dip galvanizing line as well as a rewinding and inspection line by SMS group will be integral parts of the expanded cold rolling complex.