The following items are key technologies to implement the successful endless rolling.
- Dynamic APFC (Automatic Profile & Flatness Control)
- Shear to split long strip before coiling
- Dynamic switching over of coilers during high- speed rolling and coiling
Primetals Technologies is the only supplier in the world that can supply a complete endless rolling system, and five hot strip mills are under operation with our endless rolling technology, with remarkable accomplishments. Primetals Technologies offers, in connection with the above, the following proven technologies for the customer.
- Dynamic Pair Cross Mill
- High-speed shear
- Advanced down coilers with switch-over function (Option: Carrousel coiler)
Fig.1- Dynamic APFC | Fig.2- High-speed shear | Fig.3- Coilers with switch-over function
Dynamic Pair Cross Mill
The Dynamic Pair Cross Mill consists of mill stands in which the angle at which the roll axes cross can be adjusted during the rolling process. The feature allows the control of strip crown and strip shape during rolling (Dynamic APFC) in order to deal with flying strip thickness changes and growth of roll thermal crowns which occur during continuous rolling.
The application and number of Dynamic Pair Cross Mill stands are customized in accordance with product range and other requirements.
The Dynamic Pair Cross Mill can also be effective for normal batch rolling for compensation of thermal expansion of the work rolls and changes in other rolling conditions in the transfer bar.
High Speed Shear
The High Speed Shear splits the continuous strip produced by endless rolling prior to coiling. It is a rotary-type shear equipped with an eccentric mechanism. Before shearing, the drums are rotating with a gap in order to let the strip pass through. At shearing the eccentric mechanism narrows the gap and knives mounted on the drum approach the shearing position. The speed of the drum is synchronized with the speed of strip at shearing.
High-Speed Down Coiler with Threading Direction Change
Endless rolling requires the coiling facility to have special features. Threading in the active coiler starts immediately after the preceding strip had passed. The threading speed is higher than in normal batch rolling. In order to continue coiling without a time gap, the coiler is equipped with a switch-over function which can change the direction of threading at high speed. Pinch roll with an offset adjustment system is the core technology for this. To ensure stable threading at the carry-over table between No. 1 and No. 2 coilers, a pneumatic strip feeding system is introduced. Also, the down coiler its self has a special configuration of 4 four wrapper rolls which enables smooth and quality coiling under demanding conditions.
Primetals Technologies were the first in the world to develop a hot rolling carrousel coiler. This is an alternative option to the down coiler.
Fig.4- Carrousel Coiler | Fig.5- Carrousel Coiler in operation