According to relevant industry analysis, in China, production lines for aluminum plate processing has been developing toward wide plates, and as the most typical representative, the 2800mm single stand 6 rolling mill project of Nanshan Aluminum is being currently implemented as scheduled (Nanshan Aluminum is the only listed company focusing on aluminum products in China, and the Company has been topping other large aluminum enterprises in terms of corporate size and production output) and is expected to put into operation by the end of 2014. This project was undertaken by ABB China and SMS, which may mill aluminum products with a maximum width of 2650 mm, reaching a record in width of cold rolling mills for aluminum plates in China.
ABB has cooperated with Nanshan Aluminum for a long time. Early in 2003, ABB built two 2300mm wide single stand production lines for Nanshan Aluminum, which set a benchmark for the construction of the same type roller mills, and construction of the same type of roller mills had become all the rage across China and ABB had also undertaken more than 10 high-end aluminum rolling mill projects in China afterwards. In 2012, ABB built a three stands continuous cold rolling mill production lines for Nanshan Aluminum, which was the first in Asia and the second in the world. This time, Nanshan Aluminum builds this 2800 mm single stand rolling mill project, aiming at the global high-end market, and the fact that it cooperates with ABB again demonstrates its recognition of ABB’s comprehensive strengths.
ABB is responsible for the design, debugging of the electrical and automation systems for the project as well as the follow-up services. ABB mainly supplies equipment and systems, including distribution systems, MCC, primary and secondary automatic control systems, motors and transmission systems, special instruments, operating floors and cases, and fields sensors.
This project has many features in electrical systems and automation systems and we would like to introduce as below:
Feature 1: All final transmission systems for the rolling line utilize imported ABB motors
Rolling mill stands imported from ABB Finland are equipped with main motors with a power up to 6,500 kW and a voltage grade of 3,150 V, and are also equipped with ABB ACS6000 medium voltage drive transmission systems. Most motors equipped for other parts are also imported ABB products.
Feature 2: DTC core technology provides the transmission systems unbeatable excellent dynamic properties
Medium- and low-voltage motor driving systems utilize ABB’s traditional DTC technology. Compared with PWM and other control modes, DTC has a significant advantage in response time: at a frequency of less than 40 Hz, the typical torque response time may reach a super level of 1-2 ms, 10 times faster than that of traditional control modes. DTC technology may easily achieve high precision control on motor speed and torque without speed encoders.
The nature of DTC technology determines its high energy conservation. When the system works, the adaptive motor model-based high-speed digital microprocessors might capture actual flux and torque from motors at a speed of 40,000 computations per second and compare the captured values with settings, and the system may only make adjustments when there is any difference between the settings and readings. As a result, in terms of the principle of operation, DTC technology provides theoretical basis for energy saving.
Feature 3: This is the first time for EDT milling mode to be used in aluminum mills in China, which ensures features of ordinary rolling and roughen rolling
In order to better meet the market demands, Nanshan Aluminum demanded that this rolling mill shall provide roughen rolling features, and some final products require surface texturing by EDT rolling. . In consideration of this, ABB designed EDT rolling mode for this rolling mill, in other words, use the upper intermediate roll extended bending system instead of the hydraulic screw down cylinder for rolling, so as to achieve roughen rolling with low rolling force. In addition to special electric spark roughen rollers for working rolls and special roller types for intermediate rollers, for EDT rolling, it is even more important to achieve stable rolling with small rolling reductions (rolling force ≤200t, far below the normal rolling force level). However, when the rolling reduction is less than 10%, if we continue to use normal hydraulic pressure cylinders (which provide a maximum rolling force of 30MN), we cannot meet requirements on rolling stability and control precision for roughen finishing.
As a result, for ABB, the key point is how to integrate the existing general rolling strategies and roughen finishing, and based on the mathematical model rolling mill and secondary process control, the system may switch rolling modes safely and reliably optimize rolling process control.
Feature 4: Achieve highest standard in the industry for all indicators
Nanshan Aluminum has always been strict with precisions of systems and equipment. The reason why it has long been cooperating with ABB is that, ABB may provide a wide range of mature technologies and products across electrical and automation entire industry chains, covering motors, transmission systems, instruments and meters as well as control systems, so that Nanshan Aluminum may achieve the highest indicators in the industry and lead the development of the industry. For example, for this Project, thin aluminum plate may achieve 8I-Units, and the thickness control may achieve a precision of 2 um, static tension may achieve a control precision of 1.5%, and the speed control precision may achieve 0.01%.
Mr. Sun Yongming, Head of Paper, Metals & Cement in China said, “ABB will continue to serve global high-end metallurgy projects, and provide total solutions for upgrade and renovation of electrical and automation systems to both new and existing customers.
With advantages in excellent technology, product, service and project management in electrical and automatic systems and its great success in localization and a strong service capability, and based on win-win cooperation with international mechanical equipment suppliers, ABB has dominated most of high-end aluminum rolling mill projects market in China.
In face of the current downturn in Chinese metallurgy, Sun from ABB said honestly that, “ABB will strongly support steel, nonferrous metal enterprises to upgrade and renovate their plants, including both process upgrading or periodic equipment replacement, ABB will provide personalized and marketed-oriented total solutions in solution design, equipment selection and control strategy as well as other steps in consideration of corporate situation and latest technology development trend. ABB has also obtained good practical experiences in Panzhihua Steel, Ningbo Baoxin Steel and many other enterprises.”