Application of Siemens PLC in slab continuous cast

Application of Siemens PLC in slab continuous casting system

Abstract: This paper mainly introduces the production process and system overview of slab continuous casting, as well as the application of Siemens PLC in the 4 # slab caster system of Liugang

Keywords: PLC caster remote station frequency converter PROFIBUS dp

application of Siemens PLC in bill caster

abstract:this text mainly introduces the production craft of the bill caster and its system general, also the application of Siemens PLC in No.4 bill caster of liugang

key words: PLC caster remote station translator PROFIBUS DP

I. overview

since entering the 21st century, with the continuous progress of continuous caster technology, the metallurgical industry has higher requirements for the efficiency of continuous casting. Improving the automation level of continuous casting plays a vital role in ensuring the quality of slab, improving the labor productivity of continuous casting machine, increasing the metal convergence rate of caster, and reducing the labor intensity of workers. The 4 # slab caster in Liugang converter plant is a vertical bending straight arc caster with an arc radius of 9 meters, which can produce slabs with a width of 1400~1800 mm and a thickness of 180~250 mm. In the automatic control system of this slab, Siemens PLC and its network are widely used because of its simple interface, convenient configuration, easy programming and strong real-time performance

II. Introduction to production process

process flow chart is as follows:

III. system introduction

according to the characteristics of the production process of slab caster, the automatic information system is divided into two levels, namely, level 1 basic automation system and level 2 process control computer system, with some management functions. L1 is a complete set of electric/instrument integrated control system. Its main functions of metallographic and flaw detection equipment include: first, completing the logic/sequence control and operation of each process device and the setting of process parameters; 2、 The process parameters can be used as an excellent high molecular polymer sand fixing material, the display and alarm of equipment status and the monitoring of process flow picture; 3、 Process control and computer communication. The functions of L2 include model calculation, parameter setting, quality tracking, etc

in terms of network configuration, the upper computer (winccc operation station) and PLC are connected through the industrial Ethernet converted into 100Mbps through the optical fiber transceiver, and the data exchange is realized through the tcp/ip protocol. The data sharing between the CPUs of each PLC is realized through the multiple connections included in the MPI interface mechanical testing experimental machine. The communication between PLC and remote i/o and frequency converter is realized through PROFIBUS DP. PROFIBUS DP is mainly used for high-speed data transmission of industrial automation system to realize adjustment and control functions. It is a kind of high-speed and low-cost communication, which is used for the communication between equipment level control system and decentralized i/o. It is the extension of computer network communication to field level. The system network diagram is as follows:

1. The human-machine interface HMI

the automation control system software adopts PCS7 V5.2 software package of Siemens, the PLC control system software adopts step 7 V5.2 programming, and the upper computer HMI monitoring system adopts WinCC V5.1 programming. The system realizes all monitoring functions necessary for process control through software configuration programming, including dynamic display of various equipment states and related parameters during pouring, CRT operation and display of electrical equipment, selection of operation mode, fault alarm, operation record, real-time trend and historical trend curve, etc. So as to meet the requirements of process model automatic control, working condition monitoring, safety production, medium consumption measurement and so on, and realize the man-machine interface function of the automation system

2. Basic automation system

because Siemens PLC has high reliability and strong anti-interference ability; Convenient programming, perfect function and easy to use; The design, installation and debugging of the control system are convenient; Convenient maintenance and small maintenance workload; It has strong adaptability and flexible application, so the control system takes Siemens PLC control device as the core. The system is composed of public PLC, casting flow PLC, instrument PLC, cutting PLC and various remote stations. Each PLC adopts the latest PLC s and 300 series products of German Siemens company, and the remote station i/o adopts the products of German Turk. The main functions of each part of PLC are as follows:

public PLC: it mainly completes the control of the rotation and lifting of the ladle turret and the ladle cover, the centering control of the walking, lifting and transverse movement of the tundish truck, and the control of the hydraulic system, Before cutting, under cutting, after cutting and the control of the billet roller table and pusher, the control of the stripping dummy bar device, the dummy bar storage and centering device, and the control of the head and tail cutting output device

casting flow PLC: it mainly completes the lifting and transmission control of the drive roll of the sector section 2~13, the pressure conversion control of the clamping roll, the tracking control of the dummy bar and the billet position, the mold width adjustment and vibration control

instrument PLC: it mainly completes the control of mold cooling water flow and pressure, the flow regulation and pressure control of secondary equipment cooling water and secondary spray water, as well as the setting, acquisition, monitoring and loop regulation of other process parameters

cutting PLC: it mainly completes the control of the crane travel of the flame cutting machine, the travel and positioning of the cutting gun, the lifting of the lower cutting roller table, and the control of the rear cutting roller table

each remote station: the whole system is divided into decentralized control units according to the different control function areas, and the points to be collected and controlled by PLC are distributed to the field console and box by PROFIBUS. I/o stations are set in the on-site operation console and box (such as ladle operation console, cutting operation console, billet discharging operation console, etc.) to realize decentralized remote control. In this way, the control cables led from the operation console and box through the terminals can be greatly reduced. Not only is the system simple and reliable, but also saves investment and facilitates maintenance

3. Speed regulation drive control system

the electric drive adopts the full digital vector control frequency conversion speed regulation device of SIMOVERT Masterdrives 6SE70 Series and Micromaster 440 series of Siemens company. 440 series frequency converters are mainly used in flame cutting machines, and the rest are controlled by 6SE70 Series frequency converters. Micromaster 440 universal frequency converter is controlled by microprocessor and adopts insulated gate bipolar transistor (IGBT) with modern advanced technology as power output device. Therefore, it has high operation reliability and functional diversity, and the comprehensive and perfect protection function provides good protection for the frequency converter and motor

IV. description of main control functions

1. Ladle turret and intermediate tank car control

ladle with qualified molten steel is hoisted to the ladle arm of ladle turret by crane, and the ladle arm rotates to the pouring position, waiting for casting. The preheated tundish is transported to the top of the crystallizer by the tundish truck, and the tundish is lowered and centered in place. After the molten steel tank descends, manually open the sliding nozzle, and the molten steel enters the intermediate tank through the long nozzle. After the molten steel in the tundish reaches a certain weight, manually open the stopper of the tundish, and the molten steel flows into the crystallizer through the submerged nozzle

2. Ingot feeding and de ingot control

ingot feeding: after the automatic ingot feeding command is issued, the ingot dummy bar storage trolley runs backward, and the ingot dummy bar is sent to the roller table after cutting. After it is in place, the trolley stops, four centering cylinders are pushed out for centering, and then the roller table is started after cutting, under cutting and before cutting, and the dummy bar is sent into the horizontal sector at a speed of 30 m/min. When the tail of dummy bar leaves the 2# photocell, the roller table stops after cutting. When the head of dummy bar reaches 1# photocell, the roller table before cutting and under cutting stops running. After the console sends a confirmation instruction that also shows the government's confidence in supporting the development direction of lithium batteries, the roller table runs in the sector at a speed of 5 m/min. at the same time, the encoder installed in sections 2, 7 and 13 begins to track, the sector drive roller is pressed down section by section, and the dummy bar is clamped and sent to the lower mouth of the crystallizer

take off dummy bar: when the dummy bar comes out of the sector and reaches the 1 # photocell, the take off dummy bar device separates the dummy bar head from the slab, and the dummy bar is quickly sent to the roller table after cutting. When the dummy bar reaches the 2 # photocell, the roller table stops after cutting, and then the dummy bar storage trolley runs upward to move the dummy bar sideways for storage, waiting for the use of the next pouring

3. Automatic cutting control of flame cutting machine

under automatic state, The infrared sizing system sends a signal to the PLC of the flame cutting machine. The flame cutting machine begins to pre compress, and the cutting gun moves to the edge of the slab for positioning, and the preheating oxygen valve and gas valve are opened. After reaching the fixed distance, the indenter of the flame cutting machine is pressed down, the granulating water and cutting oxygen are opened, and the billet is cut. When the cutting gun reaches the edge of the cutting lower roller table, the cutting roller swings downward, and then swings upward and returns to its original position after the cutting gun leaves the cutting roller. After the 1 # and 2 # cutting guns meet, the 2 # gun returns, the 1 # gun continues to cut forward, and the 1 # gun returns to its original position after cutting, and then the cutting roller starts to operate, and the billet is sent to the offline roller table

4. Control of conveying roller table and pusher

the conveying roller table system includes the front cutting roller table, the lower cutting roller table, the rear cutting roller table and the lower transfer roller table. When the flame cutting machine sends the cutting completion signal, the roller table starts to rotate forward after cutting. When the 2# photocell detects the slab, the lower roller table starts. When the tail of the slab leaves the 2# photocell, the roller table stops after cutting. When the 3# photocell detects the slab, the lower roller table stops. Then, the pusher pushes the billet onto the cooling bed for cooling, and then quickly returns to wait for the next billet

v. realization of key technologies:

1. Variable frequency speed control technology:

ladle turret, intermediate tank car, crystallizer vibration, sector roller table, conveying roller table, flame cutting machine, pusher and other equipment adopt variable frequency speed control technology. PLC transmits the control command to the frequency converter through the remote i/o scanner communication mode, and receives the real-time feedback information of the frequency converter status at the same time; The control program uses mov commands to transmit command information such as start/stop, forward/reverse, speed setting value, etc. to the frequency converter in the data format of output words, so as to realize the automatic control of variable frequency speed regulation

the mold vibration adopts the homology mode (the vibration frequency changes with the change of the casting speed), that is, the frequency of the mold vibration is controlled according to the following formula: F (frequency) =av (casting speed) +b, where a=20, b=80

2. Automatic tracking technology of casting flow:

incremental encoder directly uses the photoelectric conversion principle to output three groups of square wave pulses a, B and Z phases; A. The phase difference between the two groups of B pulses is 90, so the rotation direction can be easily determined, while the Z phase is one pulse per rotation, which is used for the positioning of the reference point. Its advantages are simple principle and structure, the average mechanical life can be more than tens of thousands of hours, strong anti-interference ability, high reliability, suitable for long-distance transmission. An A-B incremental encoder (1024 pulses/circle) is installed on the motor of the driving roller in the fan section. The casting flow PLC automatically calculates and completes the full-automatic control of the secondary cooling zone water distribution, motor speed measurement and billet length measurement under the ingot feeding and guiding mode and pouring mode according to the number of pulses sent by the encoder to the high-speed counting template

tracking length = pulse equivalent x number of pulses

= transmission ratio x encoder resolution X number of pulses ÷ roller circumference

3. Infrared sizing technology

infrared camera automatic sizing control system is to image the red hot steel billet in a long distance in real time through the infrared camera, and then digitize the real-time image and transmit it to the CPU. The CPU distinguishes the steel billet head after a series of operations and fuzzy recognition, and sends a cutting signal according to the set sizing length, Inform PLC to control flame cutting machine