A method and system for controlling the first slab in a finishing roll change

Abstract

The application provides a kind of finishing roll changing first slab control method and system, the method includes: setting roll changing first slab flag column in the steel grade layer parameter table, the preset interval in the steel grade layer is divided into roll changing first slab steel grade layer, and roll changing first slab steel grade layer is configured roll changing opening process parameter;Monitoring the roll changing state of finishing work roll, if the roll changing state meets the preset roll changing condition, the slab with the first position in the list of slab to be discharged is determined as roll changing first slab, and the roll changing first slab flag of roll changing first slab is set to active state;In the process of finishing preset calculation on current slab, if the roll changing first slab flag of current slab is in active state, the roll changing first slab steel grade layer corresponding to the steel grade is determined according to the roll changing first slab flag and the steel grade of current slab;According to the roll changing first slab steel grade layer, the corresponding roll changing opening process parameter is called, and finishing preset calculation is carried out based on roll changing opening process parameter.

Description

Technical Field

[0001] This invention relates to the field of process control technology for hot strip steel rolling in metallurgy, and particularly to a method and system for controlling the first slab during finishing mill roll changing. Background Technology

[0002] In hot strip mill production lines, the finishing mill work rolls need to be replaced periodically after reaching the target rolling mileage or rolling tonnage. The first slab after the finishing mill work rolls are changed refers to the first slab to enter the finishing mill for rolling after the work rolls are changed. Because the surface temperature of the newly replaced work rolls is lower, the friction coefficient is higher, and a stable oxide film has not yet formed, the rolling boundary conditions of this first slab are significantly different from those of slabs in conventional continuous rolling. If conventional high-speed, high-flow-rate process parameters are used when starting rolling after the roll change, problems such as difficulty in strip head biting, strip deviation, and waviness and breakage on the back stand can easily occur. Currently, the process parameter settings for the first slab after the roll change in the control system rely on manual correction, which is prone to errors or omissions or untimely manual settings, leading to problems such as unstable strip threading, deviation, and waviness in the first slab after the roll change. Summary of the Invention

[0003] This invention provides a method and system for controlling the first slab in a finishing mill roll change, in order to solve the technical problem in related technologies where the process parameters for the first strip in a finishing mill roll change depend on manual setting, which can easily lead to instability in the first strip threading and abnormal quality control of subsequent slabs due to untimely setting or failure to restore normal parameters.

[0004] This invention provides a method for controlling the first slab in a finishing mill roll change, comprising: Set a first roll change flag column in the rolling grade layer parameter table, divide the preset interval in the rolling grade layer into the first roll change steel grade layer, and configure the roll change start rolling process parameters for the first roll change steel grade layer; Monitor the roll changing status of the finishing mill work rolls. If the roll changing status meets the preset roll changing conditions, then the slab with the first exit sequence number in the list of slabs to be exited is determined as the first slab to be changed, and the roll changing first slab mark of the first slab to be changed is set to the valid state. During the pre-setting calculation for finishing rolling of the current slab, if the first roll change mark of the current slab is in a valid state, the first roll change steel grade layer corresponding to the steel grade is determined according to the first roll change mark and the steel grade of the current slab; the corresponding roll change and rolling process parameters are called according to the first roll change steel grade layer, and the pre-setting calculation for finishing rolling is performed based on the roll change and rolling process parameters.

[0005] In one embodiment of the present invention, the monitoring of the roll changing status of the finishing mill work rolls, if the roll changing status meets the preset roll changing conditions, determines the slab with the first exit sequence number in the list of slabs to be exited as the first slab to be changed, and sets the first roll changing mark of the first slab to be changed to an active state, including: The rolling mill monitors the roll changing status of each stand in the finishing mill in real time and counts the number of roll changing stands. If the number of roll changing stands is greater than or equal to 3, the latest list of 20 slabs to be unloaded from the heating furnace and their unloading sequence numbers are retrieved. The slab with the furnace exit sequence number 1 in the list of slabs to be removed from the furnace is identified as the first slab to be replaced by the roller. The first roller replacement flag of the first slab to be replaced by the roller is set to 1, and the first roller replacement flags of the remaining slabs in the list of slabs to be removed from the furnace are set to 0.

[0006] In one embodiment of the present invention, the method further includes: if the number of roll changing stands is less than 3, the roll changing state is determined to be a partial roll changing state, and the control process of the first slab for roll changing is not triggered; conventional process parameters are called according to conventional steel grade layers, and conventional slab process parameter values ​​and finishing mill pre-set calculations are performed on the slabs in the list of slabs to be produced.

[0007] In one embodiment of the present invention, the method further includes: After the first slab exits the furnace after the roll change, monitor whether a lifting signal for the first slab is received. The lifting signal includes a furnace lifting signal or a rolling line area lifting signal. If the cancellation signal is received, the first slab of the roll change is marked as cancelled, and the roll change first slab mark of the first slab of the roll change is verified to be in a valid state. If the first roll changer mark is in a valid state, then the next slab to be unloaded with the unloading sequence number 1 is determined from the updated list of slabs to be unloaded, and the next slab to be unloaded is re-determined as the first roll changer slab, and the first roll changer mark of the next slab to be unloaded is set to a valid state.

[0008] In one embodiment of the present invention, the roll-changing process parameters include the maximum finishing speed, the number of strip cooling water setting groups, and the strip shape setting parameters, which are different from the conventional slab process parameters.

[0009] The present invention also provides a control system for the first slab of a finishing mill roll change, comprising: The data configuration module is used to set the first roll change flag column in the rolling grade layer parameter table, divide the preset interval in the rolling grade layer into the first roll change steel grade layer, and configure special rolling start parameters for the first roll change steel grade layer. The monitoring and marking module is used to monitor the roll changing status of the finishing mill work roll. If the roll changing status meets the preset roll changing conditions, the slab with the first exit sequence number in the list of slabs to be exited is identified as the first slab to be changed, and the first roll changing mark of the first slab to be changed is set to an effective state. The layer determination module is used to determine the corresponding first roll steel grade layer based on the first roll change mark and the rolling grade of the current slab during the pre-set calculation of the finishing rolling of the current slab. The parameter calling module is used to call the corresponding special process parameters for roll change and rolling start based on the first steel grade layer of the roll change, and to perform pre-set calculations for finishing rolling based on the special process parameters for roll change and rolling start.

[0010] The beneficial effects of this invention are as follows: The present invention proposes a method and system for controlling the first slab of a finishing mill roll change. By expanding the first slab marker column in the rolling grade layer parameter table in situ and independently dividing the preset interval into the first slab steel grade layer, the special process parameters of the first slab of the roll change are physically isolated from the conventional process parameters in the data storage structure. Combined with the real-time monitoring logic of the finishing mill roll change status, the control system can automatically lock the first slab in the list of slabs to be unloaded and set its first slab roll change marker to an effective state when the preset roll change conditions are met. During the finishing mill pre-setting calculation, after reading the effective marker, the process parameter retrieval path is automatically redirected to the first slab steel grade layer of the roll change, thereby calling the roll change and rolling start process parameters for finishing mill pre-setting calculation. This solves the problems of strip threading deviation, back stand wavy rolling, and steel pile-up caused by untimely manual setting or input errors by operators. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0012] In the attached diagram: Figure 1 This is a flowchart illustrating a method for controlling the first slab during a finishing mill roll change, as provided in an embodiment of the present invention. Figure 2 This is a block diagram of the first slab control system for finishing mill roll changing provided in one embodiment of the present invention. Detailed Implementation

[0013] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0014] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0015] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0016] The inventors discovered that the work rolls of the finishing mill in a hot strip rolling production line are replaced after the strip has reached a certain rolling mileage or tonnage. To ensure the stability of the first strip head threading and overall rolling when the finishing mill starts rolling after the roll change, the finishing mill operator often limits parameters such as the number of cooling water groups, maximum speed, and bending force of the finishing strip when the roll change starts, in order to improve the rolling stability of the first strip when the finishing mill starts rolling after the roll change. In existing technologies, due to the lack of a method for controlling the first slab after roll change, the process parameters for the first slab during roll change are manually set by the finishing mill operator on the screen. However, in actual production, operators often forget to set the rolling process parameters or forget to cancel them after setting them, leading to instability in the rolling of the slab after roll change and abnormal control of subsequent slab final rolling temperature and thickness. For example, if the maximum speed of the first slab during roll change is not limited, the preset threading speed of the first slab will be too high, resulting in deviation and wavy steel accumulation at the head of the threading. If the maximum speed limit for the first slab is not canceled in time after the first slab is rolled, it will lead to multiple consecutive slabs with low head final rolling temperature and excessive head thickness, resulting in quality accidents. The main problems with existing technologies are as follows: 1. The process parameters for the first roll of the finishing mill are currently set manually by the operator. This poses a risk of scrap steel and quality accidents due to untimely intervention or cancellation of major parameters, which affects the stability of the production line's quality control. 2. In the current technology, all parameter limits for the first roll of rolling are manually entered by the operator on the screen, which poses a significant risk of human input errors and increases the workload of manual intervention for the operator, as well as the repetitive labor intensity of the finishing mill operator.

[0017] Based on the problems existing in the above-mentioned related technologies, the present invention provides a method and system for controlling the first slab of the finishing mill roll change. The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0018] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for controlling the first slab during finishing mill roll changing, according to an embodiment of the present invention. The control method includes: Step S100: Set the first roll change flag column in the rolling grade layer parameter table, divide the preset interval in the rolling grade layer into the first roll change steel grade layer, and configure the roll change start rolling process parameters for the first roll change steel grade layer.

[0019] In some embodiments, a first roll change flag column is added to the rolling grade layer parameter table to classify the first roll steel grade layer. The rolling grade layer parameter table is the basic parameter table used when retrieving process parameters for pre-set calculations in finishing rolling. By setting the first roll change flag column in this parameter table, the same rolling grade can correspond to different steel grade layers according to the conventional slab state and the first roll change slab state. Exemplarily, the rolling grade layer parameter table includes a steel grade field, a steel grade layer field, and a first roll change flag field. The steel grade field is used to record rolling grades such as Q235B, and the steel grade layer field is represented by BPMSKEY and used to record the layer code. The first roll change flag field is represented by FIRST and used to distinguish between the conventional steel grade layer and the first roll change steel grade layer. This embodiment adds the first roll change flag field to the existing parameter table and classifies the first roll change steel grade layer without changing other existing fields. The first roll change flag is used to indicate whether the slab is in the valid state of the first roll change slab. The "valid state" indicates that the pre-set calculations for finishing rolling require calling the roll change process parameters according to the first steel grade layer during roll change. In a specific example, the valid state is set to 1, and the invalid state is set to 0.

[0020] In some embodiments, process technicians can pre-configure and optimize special process parameters for roll changing that correspond to the first steel grade layer of the roll changing in the speed parameter table, strip cooling water parameter table, and strip shape setting parameter table.

[0021] Step S110: Monitor the roll changing status of the finishing mill work roll. If the roll changing status meets the preset roll changing conditions, the slab with the first exit sequence number in the list of slabs to be exited is determined as the first slab to be changed, and the first roll changing mark of the first slab to be changed is set to the valid state.

[0022] In one embodiment, the roll changing status can be derived from the roll changing completion information of each stand fed back by the basic automation system. The secondary system of the rolling line determines whether the current roll changing event meets the preset roll changing conditions based on the status information of each stand. The preset roll changing conditions are used to determine whether the special process parameters for finishing rolling of the first slab after roll changing need to be pre-set and calculated. The preset roll changing conditions can be determined by the number of roll changing stands. In the specific configuration of this embodiment, when the number of roll changing stands is greater than or equal to 3, the preset roll changing conditions are met; when the number of roll changing stands is less than 3, the preset roll changing conditions are not met.

[0023] After the preset roll changing conditions are met, the secondary system of the rolling line obtains the latest list of slabs to be rolled from the heating furnace. The list of slabs to be rolled contains at least the most recent 20 slabs to be rolled and their corresponding rolling sequence numbers. The secondary system of the rolling line determines the slab with the first rolling sequence number as the first slab to be rolled. Specifically, the first rolling slab marker for the slab with the rolling sequence number 1 is set to 1, and the first rolling slab marker for the remaining 19 slabs is set to 0.

[0024] In step S120, during the pre-setting calculation of the current slab for finishing rolling, if the first roll change mark of the current slab is in a valid state, the first roll change steel grade layer corresponding to the current steel grade is determined according to the first roll change mark and the current slab's rolling grade.

[0025] In one embodiment, for the same rolling grade, if the first roll change mark is invalid, it points to the conventional steel grade layer; if the first roll change mark is valid, it points to the first roll change steel grade layer.

[0026] Step S130: Call the corresponding roll change rolling process parameters according to the first steel grade layer of the roll change, and perform pre-set calculations for finishing rolling based on the roll change rolling process parameters.

[0027] In one embodiment, the secondary system of the rolling mill retrieves specific process parameters, including the maximum finishing speed, the number of strip cooling water setting groups, and the strip shape setting parameters, from the corresponding process parameter table based on the grade and layer of the first steel strip during roll changing. The retrieval results are then provided to the finishing mill pre-setting calculation model to participate in the primary and secondary finishing mill pre-setting calculations. After the finishing mill pre-setting calculations are completed, the calculation results are sent from the secondary system to the basic automation system for execution.

[0028] In some embodiments, the method further includes the following steps: after the first slab of the roll change is discharged from the furnace, monitoring whether a cancellation signal for the first slab of the roll change is received, the cancellation signal including a cancellation signal after the furnace or a cancellation signal in the rolling line area; if a cancellation signal is received, the first slab of the roll change is marked as cancelled, and the roll change first slab mark of the first slab of the roll change is verified as being in a valid state; if the roll change first slab mark is in a valid state, the next slab to be discharged from the updated list of slabs to be discharged is determined with a discharge sequence number of 1, the next slab to be discharged is re-determined as the first slab of the roll change, and the roll change first slab mark of the next slab to be discharged is set to a valid state.

[0029] Specifically, the system determines whether a cancellation signal has been received after the first slab exits the furnace. The secondary rolling line system monitors the furnace cancellation signal and the rolling line area cancellation signal associated with the first slab in the current roll change event. The furnace cancellation signal indicates that the slab has been cancelled at the furnace exit roller table; the rolling line area cancellation signal indicates that the slab has entered the rolling line area but has not entered the finishing mill. The cancellation signal may include the slab identifier and cancellation area of ​​the cancelled slab. The secondary rolling line system locates the current slab's data record based on the slab identifier and updates the slab's production status to cancelled. At the same time, the system determines whether the cancelled slab is the first slab in the current roll change event. If the first slab in the roll change flag of the cancelled slab is 1, it indicates that the first slab in the roll change event has not entered the finishing mill for rolling. After updating the list of slabs to be unloaded from the heating furnace, the next slab to be unloaded with a sequence number of 1 is re-determined as the first slab to be unloaded from the latest list, and its first roll change flag is set to active. In the specific configuration using 0 and 1 to represent the first roll change flag, the first roll change flag of the next slab to be unloaded is set to 1. For other slabs in the updated list of slabs to be unloaded, the flag can remain at 0.

[0030] In some implementations, the rolling mill grade layer parameter table uses the rolling mill grade layer parameter file bpms_key.csv. This file includes a steel grade field 1, a steel grade layer field 2, and a roll change first flag field 3. The field name for steel grade layer field 2 is BPMSKEY, and the field name for roll change first flag field 3 is FIRST.

[0031] In the bpms_key.csv file, the value of field 3, the first roll change flag, can be represented using Boolean logic. The flag value for a regular slab is 0, while the flag value for the first roll change slab is 1. This allows the secondary rolling line system to directly determine whether the current slab has entered the retrieval path for the special process parameters of the first roll change steel grade layer before pre-setting calculations. The encoding range of field 2, the steel grade layer, includes P01 to P320. In this embodiment, layers P61 to P70 are classified as first roll change steel grade layers, and P01 to P60 and P71 to P320 are classified as non-first roll change steel grade layers. Ten first roll change steel grade layers can be configured for P61 to P70, meaning ten different first roll change rolling steel grades can be configured. Process technicians can configure the first roll change rolling process parameters, such as the maximum finishing speed, the number of strip cooling water sets, and the shape setting parameters, in the finishing rolling process parameter table for layers P61-P70 based on the correspondence between the grade and the first roll steel grade layer. For example, the same steel grade Q235B can correspond to a non-roll change first steel grade layer under normal conditions, and to P61 under the roll change first steel grade condition. When the roll change first steel grade mark is 0, the control system uses the normal parameter layer P01; when the roll change mark is 1, the control system uses the special process parameter layer P61 for the roll change first steel grade. Taking the maximum rolling speed of finishing mill and strip cooling water parameters as examples, the maximum speed in the finishing mill speed parameter table of the normal parameter layer is 8.5 m / s, and the number of strip cooling water setting groups in the strip cooling water parameter table is 3; in the special process parameter layer of the roll change first steel grade, the maximum speed in the finishing mill speed parameter table is 7 m / s, and the number of strip cooling water setting groups in the strip cooling water parameter table is 2. When the first slab marking for roll change is 1, the steel grade layer P61-P70 of the first slab is determined by the first slab marking and the rolling grade. The steel grade layer number of the first slab is obtained, and the corresponding finishing rolling process parameters of the steel grade layer number P61-P70 of the first slab are found in the finishing rolling pre-set calculation. This achieves special control over the process parameter values ​​of the first slab after roll change, eliminating the need for operators to manually intervene and correct the process parameters on the screen before each roll change. This automatically distinguishes the process parameter values ​​of the first slab after roll change from those of the regular slab, thereby improving the head threading and overall rolling stability of the first slab after roll change.

[0032] Based on the technical solutions of the above embodiments of the present invention, the following problems are solved: unstable scrap steel and multiple consecutive abnormal head thickness quality accidents caused by untimely manual restriction or untimely cancellation of process parameters for the first slab rolled during the current finishing mill roll change; the problem that the current finishing mill roll change process parameters are restricted by manual input by the operator, which poses a significant risk of human input errors; and the problem that the current finishing mill roll change process parameters require frequent manual intervention by the operator, resulting in a large amount of manual intervention on the operator's screen and high labor intensity.

[0033] Please see Figure 2 Based on the same inventive concept, this invention also provides a control system for the first slab of a finishing mill roll change. This system includes: a data configuration module 20, used to set a first slab marker column in the steel grade layer parameter table, dividing a preset interval in the steel grade layer into first slab steel grade layers for roll change, and configuring special process parameters for roll change and rolling start-up for the first slab steel grade layers; and a monitoring and marking module 21, used to monitor the roll change status of the finishing mill work rolls, and if the roll change status meets preset roll change conditions, then the slab with the first exit sequence number in the list of slabs to be exited from the furnace is marked as the first slab. The slab is identified as the first slab for roll change, and the first roll change mark of the first slab for roll change is set to an active state; the layer determination module 22 is used to determine the corresponding first roll change steel grade layer based on the first roll change mark and the rolling grade of the current slab during the pre-setting calculation of finishing rolling for the current slab; the parameter calling module 23 is used to call the corresponding special process parameters for roll change and start rolling based on the first roll change steel grade layer, and to perform pre-setting calculation of finishing rolling based on the special process parameters for roll change and start rolling.

[0034] The interaction process of each module in the specific system has been described in detail in the aforementioned method embodiments, and will not be repeated here.

[0035] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for controlling the first slab in a finishing mill roll change, characterized in that, include: Set a first roll change flag column in the rolling grade layer parameter table, divide the preset interval in the rolling grade layer into the first roll change steel grade layer, and configure the roll change start rolling process parameters for the first roll change steel grade layer; Monitor the roll changing status of the finishing mill work rolls. If the roll changing status meets the preset roll changing conditions, then the slab with the first exit sequence number in the list of slabs to be exited is determined as the first slab to be changed, and the roll changing first slab mark of the first slab to be changed is set to the valid state. During the pre-setting calculation for finishing rolling of the current slab, if the first roll change mark of the current slab is in a valid state, the first roll change steel grade layer corresponding to the steel grade is determined according to the first roll change mark and the steel grade of the current slab; the corresponding roll change and rolling process parameters are called according to the first roll change steel grade layer, and the pre-setting calculation for finishing rolling is performed based on the roll change and rolling process parameters.

2. The method for controlling the first slab during finishing mill roll changing according to claim 1, characterized in that, The monitoring of the finishing mill work roll changing status, if the changing status meets the preset changing conditions, then the slab with the first exit sequence number in the list of slabs to be exited is determined as the first slab to be changed, and the first slab to be changed flag of the first slab to be changed is set to an active state, including: The roll changing status of each stand in the finishing mill is monitored in real time, and the number of roll changing stands is counted. If the number of roll changing stands is greater than or equal to 3, the latest list of 20 slabs to be discharged from the heating furnace and their discharge sequence number are taken. The slab with the furnace exit sequence number 1 in the list of slabs to be removed from the furnace is identified as the first slab to be replaced by the roller. The first roller replacement flag of the first slab to be replaced by the roller is set to 1, and the first roller replacement flags of the remaining slabs in the list of slabs to be removed from the furnace are set to 0.

3. The method for controlling the first slab during finishing mill roll changing according to claim 2, characterized in that, The method further includes: if the number of roll changing stands is less than 3, the roll changing state is determined to be a partial roll changing state, and the control process of the first slab for roll changing is not triggered; conventional process parameters are called according to conventional steel grade layers, and conventional slab process parameter values ​​and finishing mill pre-set calculations are performed on the slabs in the list of slabs to be produced.

4. The method for controlling the first slab during finishing mill roll changing according to claim 1 or 2, characterized in that, The method further includes: After the first slab exits the furnace after the roll change, monitor whether a lifting signal for the first slab is received. The lifting signal includes a furnace lifting signal or a rolling line area lifting signal. If the cancellation signal is received, the first slab of the roll change is marked as cancelled, and the first roll change mark of the first slab of the roll change is verified to be in a valid state. If the first roll changer mark is in a valid state, then the next slab to be unloaded with the unloading sequence number 1 is determined from the updated list of slabs to be unloaded, and the next slab to be unloaded is re-determined as the first roll changer slab, and the first roll changer mark of the next slab to be unloaded is set to a valid state.

5. The method for controlling the first slab during finishing mill roll changing according to claim 4, characterized in that: The rolling process parameters for changing rolls include the maximum finishing speed, the number of strip cooling water settings, and the strip shape settings, which are different from the conventional slab process parameters.

6. A control system for the first slab in a finishing mill roll change, characterized in that, include: The data configuration module is used to set the first roll change flag column in the rolling grade layer parameter table, divide the preset interval in the rolling grade layer into the first roll change steel grade layer, and configure special rolling start parameters for the first roll change steel grade layer. The monitoring and marking module is used to monitor the roll changing status of the finishing mill work roll. If the roll changing status meets the preset roll changing conditions, the slab with the first exit sequence number in the list of slabs to be exited is identified as the first slab to be changed, and the first roll changing mark of the first slab to be changed is set to an effective state. The layer determination module is used to determine the corresponding first roll steel grade layer based on the first roll change mark and the rolling grade of the current slab during the pre-set calculation of the finishing rolling of the current slab. The parameter calling module is used to call the corresponding special process parameters for roll change and rolling start based on the first steel grade layer of the roll change, and to perform pre-set calculations for finishing rolling based on the special process parameters for roll change and rolling start.

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