Static light pressing down control model based on PLC and Wincc

Abstract

The application provides a static soft reduction control model based on PLC and Wincc, which comprises a primary PLC control system; the primary PLC control system comprises a plurality of PLC controllers, each of which is connected with an encoder, a displacement sensor, a pressure sensor and an electromagnetic valve arranged in the field; a network switch is connected with the plurality of PLC controllers, a secondary system, a tertiary system and an industrial computer with a man-machine interface. The application aims to develop a brand-new static soft reduction model by using the primary PLC and Wincc technology, so as to overcome many problems faced by the existing dynamic soft reduction technology in practical application, and provide an innovative solution for improving the quality of the casting blank, improving the production efficiency and reducing the production cost.

Description

Technical Field

[0001] This invention relates to the field of continuous casting technology for steel, and more particularly to a static light pressure control model based on PLC and WinCC. Background Technology

[0002] In steel continuous casting production, dynamic light reduction technology is widely used by steel companies at home and abroad because it can significantly improve the quality of cast billets, effectively optimize solidification structure, and solve the problems of center segregation and porosity.

[0003] However, with deeper application, its technical challenges have become apparent. First, the industrial computer and secondary software control system suffer from poor stability. Compared to PLC control systems, the industrial computer and software control systems have lower reliability in complex continuous casting environments, frequently experiencing anomalies, a problem that has persisted despite repeated optimizations by the manufacturer. Second, the requirements for roll gap precision are stringent. Long-term operation of on-site equipment leads to wear and deformation, resulting in inherent errors and large roll gap errors. Frequent calibration is necessary, consuming significant manpower, resources, and time, impacting production efficiency and enterprise operating costs. Third, factors such as steel grade, cooling, and crystallizer wear make it difficult to determine the reference roll gap, resulting in large reduction errors, which sometimes negatively affect the quality of the cast billet. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a static light pressure control model based on PLC and WinCC to solve the technical problem of poor stability of existing static light pressure control methods.

[0005] The technical means employed in this invention are as follows:

[0006] A static light-pressure control model based on PLC and WinCC includes a primary PLC control system; the primary PLC control system includes several PLC controllers, each PLC controller is connected to an encoder, displacement sensor, pressure sensor and solenoid valve installed in the field; a network switch is connected to several PLC controllers, a secondary system, a tertiary system and an industrial control computer with a human-machine interface.

[0007] Furthermore, the control method of the primary PLC control system includes reference roll gap acquisition and light pressing control.

[0008] Furthermore, the method for acquiring the reference roll gap specifically includes:

[0009] Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at a selected position on the billet under hot billet pressure is used as the reference roll gap for the straightening roll. The acquisition of the reference roll gap includes automatic acquisition and manual acquisition. The automatic acquisition includes automatic acquisition at the start of casting, automatic acquisition when changing the tundish, and automatic acquisition when exiting light pressure.

[0010] The automatic collection method for casting is as follows: the collection reference position is selected by setting the billet length L. The collection reference position is the position where the billet coordinate exceeds the distance L of the straightening roller. After casting, under the pressure of hot billet, the reference position is collected as the actual roller gap as the billet coordinate passes through each straightening roller in sequence.

[0011] The automatic acquisition method for tundish change is as follows: the coordinates of the billet joint position are calculated by taking advantage of the special situation that the casting speed returns to zero for a long time during the tundish change. The acquisition reference position is selected by setting the joint length D. The acquisition reference position is the position where the joint coordinate exceeds the distance D of the straightening roller. Under the pressure of hot billet, the reference position is acquired as the actual roller gap is collected when the coordinate increases and passes through each straightening roller in sequence as the reference roller is used as its reference roller gap.

[0012] The automatic acquisition method for light pressure withdrawal is as follows: When light pressure withdrawal occurs during production, the billet coordinates at the position of the straightening roller are recorded. The position 0.5 meters behind this coordinate is selected as the acquisition reference position. Under hot billet pressure, the reference position passes through each straightening roller in sequence as the coordinate increases, and the actual roll gap is collected as its reference roll gap.

[0013] Furthermore, the method for controlling the light pressure specifically includes:

[0014] After the continuous casting machine starts casting, the primary PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set reduction amount. After the light reduction is applied, the first tensioning roll with a non-zero reduction amount is set as the initial current roll. The primary PLC control system automatically reduces the roll gap sequentially starting from the initial current roll. The control principle is as follows:

[0015] S1. Determine if the current roll has an effective reduction amount set initially; if yes, proceed to S2; if no, determine the next stand.

[0016] S2. Determine whether the initial reference roll gap of the current roll has been collected. If yes, proceed to S3. If no, wait until the reference roll gap is collected. Calculate the target roll gap pressed down by the initial current roll.

[0017] S3. After the billet has traveled the specified distance again, execute S4.

[0018] S4. Drive the initial current roll pressure adjustment so that the actual roll gap value of the initial current roll reaches the target roll gap value of the initial current roll.

[0019] S5. Determine whether the next roller of the initial current roller has a valid pressing amount; if yes, set the next roller as the new current roller and proceed to S6; if no, the pressing is stopped and subsequent frames will no longer press down.

[0020] S6. Determine whether the reference roll gap of the new current roll has been collected; if yes, proceed to S7; if no, wait until the reference roll gap is collected; calculate the target roll gap of the new current roll.

[0021] S7. Determine if the current roller has been pressed down to the correct position. If yes, proceed to S8; otherwise, wait until it is pressed down to the correct position.

[0022] S8. Determine whether the billet travels a distance after the initial current roll passes the new current roll. If yes, execute S9; otherwise, wait until it passes the new current roll.

[0023] S9. Drive the new current roll pressure adjustment so that the actual roll gap value of the new current roll reaches the target roll gap value of the new current roll.

[0024] S10. Repeat S5 to S9 until all the leveling rollers on all frames are pressed down.

[0025] Further, in S2, the target roll gap = reference roll gap - cumulative reduction, where the cumulative reduction is the sum of the current roll gap and the previous reduction.

[0026] Further, in S1, the effective reduction amount is a single roller reduction amount of 0-10mm, and in S3, the specified distance is 0.5m.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] Unlike traditional dynamic light-pressure technologies that suffer from poor stability in industrial control and secondary software control systems, this invention relies on the casting machine's own PLC control system and WinCC host computer software. The PLC control system is renowned for its superior anti-interference capabilities and high reliability, enabling stable operation in the complex steel continuous casting environment and effectively preventing production interruptions due to system malfunctions. The WinCC host computer software offers excellent versatility and flexibility, enabling parameter setting, status display, and human-machine interaction functions such as operator input, further enhancing the stability of the entire control system and ensuring the continuity and smooth operation of the continuous casting production process.

[0029] To address the issues of stringent roll gap precision requirements in existing technologies, and the resulting wear and deformation from long-term equipment operation leading to large roll gap errors and frequent calibration, this invention utilizes an optimized static light-pressure control model to better adapt to the inherent errors of the equipment. On one hand, a PLC control system precisely controls the hydraulic cylinders to drive the straightening rollers, achieving closed-loop control of "set pressure amount → actual pressure amount → deviation correction," effectively reducing the impact of roll gap errors on the pressing effect. On the other hand, through innovative reference roll gap acquisition methods, including automatic acquisition during pouring, automatic acquisition during ladle change, and automatic acquisition upon exiting light-pressure, the reference roll gap can be accurately obtained under different operating conditions. This avoids problems such as large pressing errors caused by the difficulty in determining the reference roll gap, thereby significantly reducing the frequency of equipment calibration, reducing the investment of manpower, materials, and time, and lowering the company's operating costs.

[0030] Based on an in-depth analysis of the current state of continuous casting technology, this invention fully utilizes the stable operation of continuous casting machines under most conditions with constant temperature and constant casting speed to develop a novel static light reduction model. Through precise reduction control, the solidification structure of the cast billet can be effectively improved, resolving quality issues such as center segregation and porosity. In practical applications, this control model can accurately calculate the target roll gap based on the set reduction amount and the collected reference roll gap, and then sequentially control the reduction of each straightening roll to ensure that the cast billet receives uniform and reasonable reduction force during solidification. This significantly improves the internal and surface quality of the cast billet, increases the product qualification rate, and brings higher economic benefits to enterprises. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a structural diagram of the control system of the present invention.

[0033] Figure 2 This is a schematic diagram of the control principle for light pressure in this invention.

[0034] Figure 3 This is a schematic diagram illustrating the principle of automatic data acquisition during the pouring process of this invention.

[0035] Figure 4 This is a schematic diagram illustrating the automatic data acquisition principle of the present invention when the middle package is changed.

[0036] Figure 5 This is a schematic diagram illustrating the principle of automatic data acquisition exit under light pressure in this invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] The proposed light-pressure reduction model is a static light-pressure reduction control model based on PLC and WinCC. It is a control system implemented using the PLC control system of the casting machine itself and the WinCC host computer software. It mainly utilizes the stability and reliability of the primary PLC control system and the versatility and flexibility of the WinCC host computer. The core of the control system is mainly implemented by the PLC control program, while the human-machine interface, including parameter setting, status display, and worker operation, is implemented using WinCC software. The PLC controls the hydraulic cylinder to drive the straightening roller for precise pressure reduction through an electromagnetic reversing valve, achieving a closed-loop control of "set pressure reduction → actual pressure reduction → deviation correction". This invention is designed for a five-flow casting machine, with each flow equipped with a Siemens 400 PLC controller for on-site signal acquisition, motion control, logic operations, network communication, etc., serving as the control core. Ethernet connections are used between PLCs, between PLCs and the host computer, and with other systems, implemented through a network switch.

[0040] like Figure 1 As shown, this invention provides a static light-pressure control model based on PLC and WinCC, including a primary PLC control system; the primary PLC control system includes several PLC controllers, each PLC controller being connected to an encoder, displacement sensor, pressure sensor, and solenoid valve installed in the field; a network switch is connected to several PLC controllers, a secondary system, a tertiary system, and an industrial control computer with a human-machine interface.

[0041] Level 2 system: refers to the dynamic light pressure computer model system (completed by a server), used for dynamic light pressure control (the server mainly completes the model tracking control and interface display; the PLC is used to control the field devices, and the data is communicated between them via Ethernet).

[0042] Level 3 system: mainly used for data acquisition and status display of factory-level processes, not for control, and only for reading and data acquisition from the PLC system.

[0043] The control methods of the primary PLC control system include reference roll gap acquisition and light pressing control.

[0044] The method for collecting the reference roll gap specifically includes:

[0045] Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at a selected position on the billet under hot billet pressure is used as the reference roll gap for that straightening roll. The acquisition of the reference roll gap includes automatic acquisition and manual acquisition. The automatic acquisition includes automatic acquisition at the start of casting, automatic acquisition when changing the tundish, and automatic acquisition when exiting light pressure, such as... Figure 3-5 As shown;

[0046] The automatic collection method for casting is as follows: the collection reference position is selected by setting the billet length L. The collection reference position is the position where the billet coordinate exceeds the distance L of the straightening roller. After casting, under the pressure of hot billet, the reference position is collected as the actual roller gap as the billet coordinate passes through each straightening roller in sequence.

[0047] The automatic acquisition method for tundish change is as follows: the coordinates of the billet joint position are calculated by taking advantage of the special situation that the casting speed returns to zero for a long time during the tundish change. The acquisition reference position is selected by setting the joint length D. The acquisition reference position is the position where the joint coordinate exceeds the distance D of the straightening roller. Under the pressure of hot billet, the reference position is acquired as the actual roller gap is collected when the coordinate increases and passes through each straightening roller in sequence as the reference roller is used as its reference roller gap.

[0048] The automatic acquisition method for light pressure withdrawal is as follows: When light pressure withdrawal occurs during production, the billet coordinates at the position of the straightening roller are recorded. The position 0.5 meters behind this coordinate is selected as the acquisition reference position. Under hot billet pressure, the reference position passes through each straightening roller in sequence as the coordinate increases, and the actual roll gap is collected as its reference roll gap.

[0049] like Figure 2 As shown, the method for controlling light pressure specifically includes:

[0050] After the continuous casting machine starts casting, the primary PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set reduction amount. After the light reduction is applied, the first tensioning roll with a non-zero reduction amount is set as the initial current roll. The primary PLC control system automatically reduces the roll gap sequentially starting from the initial current roll. The control principle is as follows:

[0051] S1. Determine if the current roll has an effective reduction amount set initially; if yes, proceed to S2; if no, determine the next stand; generally, the reduction amount of a single roll is limited to 0-10mm (this value can be appropriately modified according to process requirements), that is, if the reduction amount is set to 0, the roll will not be reduced;

[0052] S2. Determine whether the reference roll gap of the current roll has been collected. If yes, proceed to S3. If no, wait until the reference roll gap is collected. Calculate the target roll gap of the current roll. Only when the reference roll gap is collected can the target roll gap be calculated. Target roll gap - reference roll gap - cumulative roll gap (the sum of the roll gap and the previous roll gap).

[0053] S3. After the billet travels a specified distance, execute S4. The specified distance is 0.5m in this embodiment to avoid the cast billet reference position being pressed, which would lead to inaccurate subsequent reference roll gap collection.

[0054] S4. Drive the initial current roll pressure adjustment so that the actual roll gap value of the initial current roll reaches the target roll gap value of the initial current roll, with an error of less than 0.1mm;

[0055] S5. Determine whether the next roller of the initial current roller has a valid pressing amount; if yes, set the next roller as the new current roller and proceed to S6; if no, the pressing is stopped and subsequent frames will no longer press down.

[0056] S6. Determine whether the reference roll gap of the new current roll has been collected; if yes, proceed to S7; if no, wait until the reference roll gap is collected; calculate the target roll gap of the new current roll.

[0057] S7. Determine if the current roller has been pressed down to the correct position. If the error is less than 1mm, it is considered to be in place. If yes, proceed to S8; otherwise, wait until it is pressed down to the correct position.

[0058] S8. Determine whether the billet travels beyond the initial current roll after the current roll passes. The center distance between two adjacent straightening rolls is 1.5m. If it is greater than 1.8m, it is considered to exceed the current roll. If yes, execute S9; otherwise, wait until it exceeds the current roll.

[0059] S9. Drive the new current roll pressure adjustment so that the actual roll gap value of the new current roll reaches the target roll gap value of the new current roll.

[0060] S10. Repeat S5 to S9 until all the leveling rollers on all frames are pressed down.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A static light-pressure control model based on PLC and WinCC, characterized in that, It includes a primary PLC control system; the primary PLC control system includes several PLC controllers, each PLC controller is connected to an encoder, displacement sensor, pressure sensor and solenoid valve installed in the field; the network switch is connected to several PLC controllers, a secondary system, a tertiary system and an industrial computer with a human-machine interface. The control method of the primary PLC control system includes reference roll gap acquisition and light pressing control; The method for collecting the reference roll gap specifically includes: Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at a selected position on the billet under hot billet pressure is used as the reference roll gap of the straightening roll. The acquisition of the reference roll gap includes automatic acquisition and manual acquisition. The automatic acquisition includes automatic acquisition at the start of casting, automatic acquisition when changing the tundish, and automatic acquisition when exiting light pressure. The automatic collection method for casting is as follows: the collection reference position is selected by setting the billet length L. The collection reference position is the position where the billet coordinate exceeds the distance L of the straightening roller. After casting, under the pressure of hot billet, the reference position is collected as the actual roller gap as the billet coordinate passes through each straightening roller in sequence. The automatic acquisition method for tundish change is as follows: the coordinates of the billet joint position are calculated by taking advantage of the special situation that the casting speed returns to zero for a long time during the tundish change. The acquisition reference position is selected by setting the joint length D. The acquisition reference position is the position where the joint coordinate exceeds the distance D of the straightening roller. Under the pressure of hot billet, the reference position is acquired as the actual roller gap is collected when the coordinate increases and passes through each straightening roller in sequence as the reference roller is used as its reference roller gap. The automatic acquisition method for light pressure withdrawal is as follows: When light pressure withdrawal occurs during the production process, the billet coordinates at the position of the straightening roller are recorded. The position 0.5 meters behind this coordinate is selected as the acquisition reference position. Under the pressure of the hot billet, the reference position passes through each straightening roller in sequence as the coordinate increases, and the actual roller gap is collected as its reference roller gap. The method for light pressure control specifically includes: After the continuous casting machine starts casting, the primary PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set reduction amount. After the light reduction is applied, the first tensioning roll with a non-zero reduction amount is set as the initial current roll. The primary PLC control system automatically reduces the roll gap sequentially starting from the initial current roll. The control principle is as follows: S1. Determine if the current roll has an effective reduction amount set initially; if yes, proceed to S2; if no, determine the next stand. S2. Determine whether the initial reference roll gap of the current roll has been collected. If yes, proceed to S3. If no, wait until the reference roll gap is collected. Calculate the target roll gap pressed down by the initial current roll. S3. After the billet has traveled the specified distance again, execute S4. S4. Drive the initial current roll pressure adjustment so that the actual roll gap value of the initial current roll reaches the target roll gap value of the initial current roll. S5. Determine whether the next roller of the initial current roller has a valid pressing amount; if yes, set the next roller as the new current roller and proceed to S6; if no, the pressing is stopped and subsequent frames will no longer press down. S6. Determine whether the reference roll gap of the new current roll has been collected; if yes, proceed to S7; if no, wait until the reference roll gap is collected; calculate the target roll gap of the new current roll. S7. Determine if the current roller has been pressed down to the correct position. If yes, proceed to S8; otherwise, wait until it is pressed down to the correct position. S8. Determine whether the billet travels a distance after the initial current roll passes the new current roll. If yes, execute S9; otherwise, wait until it passes the new current roll. S9. Drive the new current roll pressure adjustment so that the actual roll gap value of the new current roll reaches the target roll gap value of the new current roll. S10. Repeat S5~S9 until all the tensioning rollers of the frame are pressed down.

2. The static light-pressure control model based on PLC and WinCC according to claim 1, characterized in that, In S2, the target roll gap = reference roll gap - cumulative reduction, where the cumulative reduction is the sum of the current roll gap and the previous reduction.

3. The static light-pressure control model based on PLC and WinCC according to claim 1, characterized in that, In S1, the effective reduction amount is a single roller reduction amount of 0-10mm; in S3, the specified distance is 0.5m.

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