1. Introduction to cold rolling mill unit
The cold rolling mill unit includes many machine models such as two-roller, four-roller, six-roller, eight-roller, twelve-roller, sixteen-roller, eighteen-roller and twenty-roller and is suitable for cold rolling of stainless steel, plain carbon steel, alloy steel, aluminum, copper and other metal materials. The main components include main rolling mill, left coiling machine, and right coiling machine. The transmission systems are DC driving at most cases. Silicon controlled rectifier provides power supply. At entrance and exit of the rolling mill, isotope or X-ray thickness gauge is installed.
2. Configuration of basic electric system
1、The cabinet adopts combined type GGD low voltage power distribution cabinets;
2、The control system takes programmable logic controller (PLC) as the core and usually uses Siemens S7-300/400 series, FM458 series, AB SLC500 and CompactLogix, etc.
3、The DC transmission system adopts full digital DC speed adjusting device and usually uses German Siemens 6RA70 and RA80680 series, full ABB series, EUROTHERM 590 series, etc.
4、The AC transmission system adopts full digital frequency conversion speed regulator and usually uses ABB PowerFlex series, Siemens MM440 series, full Inovance series and full Emerson series, etc.
5、Equipped with HMI human-machine interface (touch screen with commonly used Siemens TP270 and MP370 series; equipped with upper supervisory control computer (Industrial Personal Computer) with commonly used Advantech series, Siemens PC 847, etc.
3. System control function
1、Perform power supply, start-stop control, operation, interlock logic, fault detect and fault handling of all transmission systems.
2、Perform interlock logic and start-stop control of all hydraulic stations, lubrication stations, cooling stations and filtration stations.
3、Carry out supervision and alarm for liquid level, pressure and temperature and other signals on the site of machine unit.
4、Carry out all types of interlock control for all sections of the whole production line at different operation modes.
5、Carry out broken tape detection and protection action.
6、Carry out automatic slow down and accurate stopping.
7、Carry out automatic measurement of steel tape length.
8、Carry out logic control of the machine unit.
9、Carry out constant tension control of the coiling machine.
10、Carry out automatic calculation and compensation for coiling diameter of the coiling machine.
11、Carry out automatic control for thickness (system with AGC hydraulic press).
4. System characteristics
1、The speed control adopts optical-electricity encoder to measure feedback, resulting in high control precision and quick dynamic response.
2、Rolling with constant tension is performed during the whole rolling process with high control precision and good stability of tension.
3、 PLC speed cascade control in combination with full digital DC speed control device ensures speed precision of the machine unit and stability and reliability of the equipment.
4、The system adopts PROFIBUS or other field buses combines PLC system and transmission system organically, which reduces wire connection among equipment, improve equipment reliability, anti-interference and accuracy of control data.
5、The supervision system equipped with upper computer records speed, current, thickness, liquid level and temperature and other signals collected from the site into database of the server. This can provide true, effective data and help to operation, repair and management.
6、The hydraulic press unit is equipped with thickness automatic control system AGC, which features high control precision and good plate shape of rolled steel tape.
7、The press motor of electric-driven press machine unit used frequency converter speed regulation, which enables the press motor to start and stop smoothly and carry out control function of multiple-stage speed.
8、The system is equipped with perfect system recognition and fault protection function to ensure that it can implement the control command of PLC control system for speed and current of all motors.
9、Able to make response quickly, make judgment quickly and carry out corresponding handling act when the system has fault.