Plant supplier SMS group has been contracted by aluminium processing company Impol Seval to revamp its aluminium hot rolling mill in Serbia.

Impol Seval’s mill will be revamped in two stages. An initial plant shutdown in the spring of 2017 will be followed by a second shutdown after six months of interim operation.

Currently, the single-stand mill rolls the reheated billets in reversing mode down to gauges of 8 mm to 15 mm and coils the strip after the final pass at gauges of between 5 mm and 10 mm.

The main objectives of the revamp are to ensure a marked increase in production and improvement in quality of the rolled strips as regards to thickness and shape tolerances.

Also, after the revamp, it will be possible to work with three coiling passes rather than only one as is the case presently. This is as a result of the integration of the entry side coiler into the production process.

To enable the mill to also roll large ingots, the entry and exit sections will be completely rebuilt. The positions of both coilers will be shifted and raised, so as to allow larger coil diameters to be wound. On both sides, the belt wrappers, pinch rolls and side guards will be renewed and adapted. At the exit end, a new trimming shear will be installed. It will be coordinated with the higher exit speed resulting from the reduced final gauge of down to 3.5 mm.

SMS group’s scope of supply will include a new X-ray measuring unit, which will continuously measure the strip gauge and shape over the strip width. The measured data will be used as input variables for the technological control systems. In the mill stand itself, new cooling headers will be installed, partly for the purpose of ensuring roll-gap lubrication and partly for allowing optimum distribution of the rolling emulsion for cooling the work rolls.

The adjustable cooling patterns are an important actuator for achieving constant strip shape. The capacity of the emulsion system will be increased by about 30%. In future, negative bending of the work roll – which is a convex setting of the roll gap – will be possible owing to the installation of additional bending cylinders in the chocks of the backup rolls. Optimum strip geometry can thus be achieved, even in the case of an increasing thermal crown of the work rolls.

To clean the rolls, a high-pressure system is to be installed as a replacement for the rotating roll brushes used until now. Emulsion will be sprayed onto the rolls at a pressure of up to 1 000 bar, which ensures that deposits and adhering aluminum residues are reliably removed from the roll surfaces.

The heart of the new mill will be the new X-Pact automation system, AluControl. It will comprise the technological control systems and the level 2 process models. Through a link to the existing production planning system, level 2 will receive all the product data and, depending on the thermal condition of the mill, calculate the optimum pass schedule and mill setting values in each case. The level 1 control systems ensure that the specified close tolerances for strip gauge and shape will be achieved. All plant data and process information will be displayed in the new visualization system in a highly user-friendly manner.

When commissioning takes place at the end of 2017, the mill will be changed over completely to the new AluControl system and start operating as a modern rolling mill producing high-quality hot strips. AluControl has been developed at SMS group over the past few years as an automation package that is specially suited to the requirements of hot and cold rolling of aluminium.

AluControl has proven its value in more than 20 installations since 2012, in new plant projects and revamps alike, and enhancements to the system have been consistently implemented.