High-stability temper mill elongation control method and system

Abstract

The invention discloses a high-stability temper mill elongation control method and system, and the method comprises the steps: calculating the inlet and outlet speed values of strip steel in a plurality of modes, and selecting the inlet and outlet speed values of the strip steel from a plurality of speed sources; when the speed source is switched, slope processing is conducted on the speed value of the strip steel, the elongation rate is calculated through the processed speed of the strip steel entering an outlet, and the actual elongation rate value is obtained after amplitude limiting and smoothing processing are conducted; the self-adaptive gain is calculated according to the strip steel width and the inlet thickness set value, the integral controller is adopted to calculate the integral part control rolling force, then the pre-control rolling force is calculated according to the actual speed of the rack, the total rolling force set value is obtained, and high-stability temper mill elongation control is achieved based on the total rolling force set value. According to the method, the accurate actual elongation value can be obtained under the complex working condition, and accurate control over the elongation of the temper mill is achieved through the method that the integral controller with the self-adaptive gain and the pre-control rolling force changing along with the speed are combined.

Description

Technical Field

[0001] The present invention relates to the field of automatic control of a leveling machine, and in particular to a high-stability elongation control method and system for a leveling machine. Background Art

[0002] The elongation of a six-high cold skin-pass mill is a key process parameter for cold-rolled strip, determining the final performance of the strip. The key control parameters in the skin-pass process are the rolling force and the tension before and after skin-passing. The primary control objectives of the skin-pass process are strip elongation and coil surface quality. The quality of the finished product is directly related to the performance of elongation control.

[0003] The strip elongation is defined as the speed difference of the strip at the inlet and outlet of the leveler divided by the inlet speed, that is:

[0004]

[0005] Where, E is the elongation of the strip, V S,Exit and V S,Entry are the speed values of the strip at the exit and entrance of the leveler respectively.

[0006] As can be seen, elongation calculation is highly dependent on the accuracy of strip speed. Therefore, speed sensors are typically installed at the entry and exit of the skin-pass mill. However, in complex on-site environments, these sensors are not always reliable and can sometimes malfunction or be subject to interference. To ensure the stability of the skin-pass mill process, a method is needed to process multiple speed measurement data to obtain accurate strip entry and exit speed values. Summary of the Invention

[0007] In view of the technical defects and technical drawbacks in the prior art, the embodiments of the present invention provide a highly stable elongation control method and system for a leveling machine that overcomes or at least partially solves the above problems. The specific solution is as follows:

[0008] As a first aspect of the present invention, a high-stability elongation control method for a leveling mill is provided, the method comprising:

[0009] Calculate the strip steel inlet and outlet speed values using multiple methods, obtain multiple speed sources and select the strip steel inlet and outlet speed values from the multiple speed sources;

[0010] When the speed source is switched, the strip speed value is ramped, and the elongation is calculated using the processed strip inlet and outlet speeds. The actual elongation value is obtained after limiting and smoothing.

[0011] The adaptive gain is calculated according to the set values of strip width and entrance thickness, and the integral part of the rolling force is calculated by an integral controller according to the difference between the set value of elongation and the actual value of elongation. The pre-control rolling force is then calculated according to the actual speed of the stand. The total rolling force set value is obtained based on the integral part of the rolling force and the pre-control rolling force. Based on the total rolling force set value, highly stable elongation control of the leveler is achieved.

[0012] Furthermore, the multiple speed sources obtained by calculating the strip inlet and outlet speed values in multiple ways include:

[0013] Pulse encoders are installed on the transmission motors of the entrance tension roller, the transmission roller and the exit steering roller of the leveler frame. The speed values of the strip at the entrance, the frame and the exit are calculated based on the measured values of the pulse encoders. S,PulseE 、V S,PulseS 、V S,PulseX ;

[0014] The speed signals of the strip at the entrance, rack and exit are filtered out by using a band-stop filter to remove the interference signal of the transmission roller rotation frequency. The speed values of the strip at the entrance, rack and exit after filtering are V and V, respectively. S,PActE 、V S,PActS 、V S,PActX ;

[0015] Laser velocimeters are installed at the entrance and exit of the leveling mill frame to measure the strip inlet and outlet speeds. The strip inlet and outlet speeds measured by the laser velocimeter are V and V, respectively. S,LActE and V S,LActX ;

[0016] The strip speed at the leveler entrance is derived from two sources: the laser velocimeter measurement value V S,LActE and V calculated by the pulse encoder measurement of the entrance tension roller S,PActE There are three sources of strip speed at the exit of the leveler: the laser velocimeter measurement value V S,LActX , V calculated by the pulse encoder of the exit steering roller S,PActX and the rack linear velocity V S,PActS Multiply by the slip coefficient S L Calculated V S,PActS ×S L , where S L The forward slip coefficient value given for the secondary system.

[0017] Furthermore, the selecting of the strip steel entry and exit speed values from a plurality of speed sources specifically includes:

[0018] The preferred speed source is the laser velocimeter. When the laser velocimeter fails or is disturbed, the system automatically switches to the pulse encoder of the inlet and outlet drive rollers to measure the speed. When the pulse encoder of the outlet steering roller fails or the roller slips, the strip outlet speed calculated by multiplying the frame linear speed by the slip coefficient will be automatically selected.

[0019] Furthermore, the speed of the strip at the corresponding position of the skin-pass mill is calculated based on the pulse encoder measurement value, where the corresponding positions include the entrance, the frame, and the exit. The formula is as follows:

[0020] V S,Pulse =N Pulse ×G EM ×π×(D R +0.5h s )

[0021] Where N Pluse is the motor speed of the corresponding roller at the corresponding position measured by the pulse encoder, G EM is the gear ratio of the motor, D R is the diameter of the corresponding roller, h s is the strip thickness at the corresponding roller position.

[0022] Furthermore, the speed signal at the corresponding position of the strip is filtered out using a band-stop filter to remove the interference signal of the transmission roller rotation frequency, including:

[0023] The signals of the single frequency and double frequency of the corresponding roller rotation at the corresponding position are filtered out from the calculated strip speed by using a band-stop filter to obtain the actual value of the strip speed at the corresponding position after filtering.

[0024] Furthermore, the actual value of the strip speed V at the corresponding position after filtering is S,PAct The calculation formula is as follows:

[0025] V S,PAct =BSF(V S,Pulse )

[0026] Where BSF represents the band-stop filter, and the transfer function of the analog band-stop filter is:

[0027]

[0028] Where A F is the filter gain, T A is the PLC sampling time, F stop is the blocking frequency, j is the unit representing the imaginary number in Laplace transform, and BW is the bandwidth.

[0029] Furthermore, when the speed source is switched, the strip speed value is ramped, the elongation is calculated using the processed strip inlet and outlet speeds, and the actual elongation value is obtained after limiting and smoothing. Specifically, the steps include:

[0030] When a change in the speed source is detected, ramp processing is performed when switching between two speed values, that is, when the speed is switched, the speed value ramps from the original value to the new value within a certain period of time;

[0031] Calculate the initial value of elongation E according to the strip inlet and outlet speed Act,ini , the formula is as follows:

[0032]

[0033] Where V S,Exit and V S,Entry are the values of the strip speed at the exit and entrance after the ramp processing when the speed source is switched;

[0034] The initial value of elongation is limited and smoothed to obtain the actual value of elongation. The formula is as follows:

[0035] E Act =PT1(LIM(E Act,ini ))

[0036] Where LIM represents the limiting link, PT1 represents the first-order smoothing link, and the discrete PT1 algorithm used in PLC is:

[0037]

[0038] Where, P PT1 (n) is the output value of the first-order smoothing link at time n, P PT1 (n-1) is the output value of the first-order smoothing link at time n-1, T PT1 is the smoothing time of the first-order smoothing link, T S is the sampling time of the PLC controller, and X(n) is the input value of the first-order smoothing link at time n.

[0039] Furthermore, the adaptive gain is calculated according to the set values of the strip width and the inlet thickness, and the integral controller is used to calculate the integral part to control the rolling force. The pre-controlled rolling force is then calculated according to the actual speed of the stand, and the total rolling force set value is obtained by adding them together. The highly stable elongation control of the skin-pass mill based on the total rolling force set value specifically includes:

[0040] Calculate the adaptive gain G of the elongation controller according to the set values of strip width and inlet thickness adapt :

[0041]

[0042] Where W Act is the actual width of the strip, W Max is the maximum width of the strip, H EntrySP Set the value for the strip entrance thickness;

[0043] Calculate the rolling force for the integral part of elongation control:

[0044] The integral controller is used to calculate the integral part of the rolling force for elongation control based on the elongation difference:

[0045]

[0046] Where, E Act is the actual value of elongation, F Int is the integral part of the rolling force controlled by the elongation, and F int (n) and F int (n-1) are the values at time n and time n-1 respectively, T E is the integral time parameter of the controller, E Set Set a value for the elongation;

[0047] The elongation control pre-controlled rolling force is calculated based on the actual speed of the skin-pass mill stand, and the total elongation control rolling force is obtained by adding the integral partial rolling force;

[0048]

[0049] Where, F SP,FM is the rolling force setting value during flattening, F SP,Thread The rolling force setting value during strip threading is given by the secondary system. Stand is the actual value of the rack speed, V Thread V is the speed setting value when threading the belt. Max is the maximum speed setting value;

[0050] The pre-controlled rolling force plus the integral rolling force is the total elongation-controlled rolling force, which is added to the original rolling force setting value to obtain the total rolling force setting value:

[0051] F SP,all =F SP,FM +F Int +F Pc

[0052] The total rolling force set value is sent to the pressure control system of the leveler, and the pressure control system controls the actual rolling force value to reach the total rolling force set value, thereby achieving high-stability elongation control of the leveler.

[0053] As a second aspect of the present invention, a high-stability elongation control system for a leveling mill is provided, characterized in that the system comprises:

[0054] The data acquisition module is used to calculate the strip inlet and outlet speed values using multiple methods and select the strip inlet and outlet speed values from multiple speed sources;

[0055] The elongation calculation module is used to perform ramp processing on the strip speed value when the speed source is switched, calculate the elongation using the processed strip inlet and outlet speeds, and obtain the actual elongation value after limiting and smoothing;

[0056] The control module is used to calculate the adaptive gain according to the set values of strip width and entrance thickness, and use the integral controller to calculate the integral part of the rolling force according to the difference between the elongation set value and the actual elongation value, and then calculate the pre-control rolling force according to the actual speed of the frame. The total rolling force set value is obtained based on the integral part of the rolling force and the pre-control rolling force, and the high-stability elongation control of the leveler is achieved based on the total rolling force set value.

[0057] Furthermore, the adaptive gain is calculated according to the set values of the strip width and the inlet thickness, and the integral controller is used to calculate the integral part to control the rolling force. The pre-controlled rolling force is then calculated according to the actual speed of the stand, and the total rolling force set value is obtained by adding them together. The highly stable elongation control of the skin-pass mill based on the total rolling force set value specifically includes:

[0058] Calculate the adaptive gain G of the elongation controller according to the set values of strip width and inlet thickness adapt :

[0059]

[0060] Where W Act is the actual width of the strip, W Max is the maximum width of the strip, H EntrySP Set the value for the strip entrance thickness;

[0061] Calculate the rolling force for the integral part of elongation control:

[0062] The integral controller is used to calculate the integral part of the rolling force for elongation control based on the elongation difference:

[0063]

[0064] Where, E Act is the actual value of elongation, F Int is the integral part of the rolling force controlled by the elongation, and F int (n) and F int (n-1) are the values at time n and time n-1 respectively, TE is the integral time parameter of the controller, E Set Set a value for the elongation;

[0065] The elongation control pre-controlled rolling force is calculated based on the actual speed of the skin-pass mill stand, and the total elongation control rolling force is obtained by adding the integral partial rolling force;

[0066]

[0067] Where, F SP,FM is the rolling force setting value during flattening, F SP,Thread The rolling force setting value during strip threading is given by the secondary system. Stand is the actual value of the rack speed, V Thread V is the speed setting value when threading the belt. Max is the maximum speed setting value;

[0068] The pre-controlled rolling force plus the integral rolling force is the total elongation-controlled rolling force, which is added to the original rolling force setting value to obtain the total rolling force setting value:

[0069] F SP,all =F SP,FM +F Int +F Pc

[0070] The total rolling force set value is sent to the pressure control system of the leveler, and the pressure control system controls the actual rolling force value to reach the total rolling force set value, thereby achieving high-stability elongation control of the leveler.

[0071] The present invention has the following beneficial effects:

[0072] 1. The present invention uses multiple methods to calculate the entry and exit speeds of the strip, and filters the pulse encoder measurement values to eliminate the influence of interference. When the detection equipment fails or is interfered with, it can automatically switch to the speed value calculated by another method. When the speed source is switched, ramp processing is also performed to achieve a smooth transition of the speed value, and accurate actual elongation values can be obtained under complex working conditions.

[0073] 2. The present invention uses an integral controller with adaptive gain combined with a pre-controlled rolling force that changes with speed to achieve precise control of the elongation of the skin-pass mill, has strong adaptive capabilities, and enhances the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 A schematic diagram of main detection instruments of a single-stand six-roller skin-pass mill provided by an embodiment of the present invention;

[0075] Figure 2A schematic flow chart of a high-stability leveler elongation control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0076] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0077] See also Figure 1 The figure shows a schematic diagram of the main instrumentation for a single-stand, six-roller skin-pass mill according to an embodiment of the present invention. Assuming the strip runs from left to right, the left side represents the entry and the right side represents the exit. The strip 4 enters the skin-pass mill 6 through the entry tension roller 1. After being leveled, it passes through the shape roller 9, which measures the strip's flatness. The strip then passes through the steering roller 10 and arrives at the coiler 11 for winding. Two laser velocimeters 2 and 7 are installed on the entry and exit sides of the skin-pass mill, respectively, to measure the actual strip speed at the entry and exit. Pulse encoders are also installed on the drive motors for the entry tension roller 1, the skin-pass mill drive roller 5, and the shape roller 9 to measure the speed of each drive motor. The skin-pass mill uses a hydraulic cylinder 3 to provide rolling force, controlling the strip's elongation. All skin-pass mill process control functions are programmed in the PLC controller 8. Specific control functions include elongation control, rolling force control, tension control, drive control, and shape control.

[0078] See also Figure 1 As shown, a highly stable elongation control method for a leveler provided by an embodiment of the present invention is used to obtain an accurate actual value of the elongation in a complex on-site environment, and to achieve stable elongation control by using an adaptive controller combined with a pre-control method. Specifically, the method includes the following steps:

[0079] S10, calculating the inlet and outlet speed values of the strip steel using multiple methods, obtaining multiple speed sources and selecting the inlet and outlet speed values of the strip steel from the multiple speed sources;

[0080] S20, when the speed source is switched, the strip speed value is ramped, the processed strip inlet and outlet speeds are used to calculate the elongation, and the actual elongation value is obtained after limiting and smoothing.

[0081] S30, calculates the adaptive gain according to the set values of the strip width and the entrance thickness, and uses an integral controller to calculate the integral part of the rolling force control according to the difference between the elongation set value and the actual elongation value, and then calculates the pre-control rolling force according to the actual speed of the frame. The total rolling force set value is obtained based on the integral part of the rolling force control and the pre-control rolling force, and the high-stability elongation control of the leveler is achieved based on the total rolling force set value.

[0082] The present invention uses multiple methods to calculate the entry and exit speeds of the strip, and also performs ramp processing when the speed source is switched to achieve a smooth transition of the speed value, so that the accurate actual value of the elongation can be obtained under complex working conditions; the present invention uses an integral controller with adaptive gain plus a pre-controlled rolling force that changes with speed to achieve precise control of the elongation of the leveling mill, has strong adaptive ability, and enhances the stability of the system.

[0083] In some embodiments, step S10 specifically includes:

[0084] S101, calculating the strip linear velocity according to the transmission roller motor speed measured by the pulse encoder.

[0085] In this embodiment, pulse encoders are installed on the drive motors of the inlet tension roller, the drive roller, and the outlet steering roller of the leveler frame. The speed values of the strip at the leveler inlet, the frame, and the outlet are calculated according to the pulse encoder measurement values as follows:

[0086] The formula for calculating the speed of the strip at the corresponding position based on the pulse encoder measurement value is as follows:

[0087] Speed value calculation formula: V S,Pulse =N Pulse ×G EM ×π×(D R +0.5h s )

[0088] Where N Pluse is the motor speed of the corresponding roller at the corresponding position measured by the pulse encoder, G EM is the gear ratio of the motor, D R is the diameter of the corresponding roller, h s is the strip thickness at the corresponding roller position, where the strip thickness at the entrance tension roller, exit steering roller and frame drive roller positions are the average of the strip entrance thickness, exit thickness and entry and exit thickness respectively.

[0089] Assume that the speed values of the strip at the entrance, rack, and exit measured by the pulse encoder are V S,PulseE 、V S,PulseS 、V S,PulseX .

[0090] In the above embodiment, the speed of the strip at the entrance V can be calculated by substituting the motor speed of the entrance tension roller, the gear ratio of the motor, the diameter of the roller, and the thickness of the strip at the entrance tension roller into the speed calculation formula. S,PulseE Substituting the motor speed of the leveler drive roller, the gear ratio of the motor, the diameter of the roller, and the thickness of the strip at the leveler drive roller into the speed calculation formula, the speed value V of the strip at the frame can be calculated. S,PulseS Substituting the motor speed of the exit steering roller, the gear ratio of the motor, the diameter of the roller and the thickness of the strip at the exit steering roller into the speed calculation formula, the speed value V of the strip at the exit can be calculated. S,PulseX .

[0091] S102: Use a band-stop filter to filter out interference signals of the transmission roller rotation frequency.

[0092] Use a band-stop filter to filter out the signals of the double frequency and double frequency of the transmission roller from the calculated strip speed to reduce interference to the control system and improve system stability. Suppose the actual value of the strip speed after filtering is V S,PAct , the formula is as follows:

[0093] The actual speed value calculation formula is: V S,PAct =BSF(V S,Pulse )

[0094] Where BSF represents the band-stop filter, and the transfer function of the analog band-stop filter is:

[0095]

[0096] Where A F is the filter gain, (T A is the PLC sampling time, F stop is the blocking frequency, j is the unit representing the imaginary number in Laplace transform), and BW is the bandwidth. In this embodiment, F is set stop =N Pulse ×G EM and 2N Pulse ×G EM ,BW=0.3,A F =1.0;

[0097] Assume that the speed values of the strip after filtering at the entrance, rack, and exit are V S,PActE 、V S,PActS 、V S,PActX .

[0098] In the above embodiment, V S,PulseE Substitute V into the actual speed value calculation formulaS,Pulse , that is, the filtered strip speed value V at the entrance is obtained S,PActE , V S,PulseS Substitute V into the actual speed value calculation formula S,Pulse , that is, the filtered strip speed value V at the rack is obtained S,PActS , V S,PulseX Substitute V into the actual speed value calculation formula S,Pulse , that is, the filtered strip speed value V at the rack is obtained S,PActX .

[0099] S103. Select the entry and exit speed values of the strip from a variety of speed sources.

[0100] In this embodiment, laser velocimeters are installed at the entrance and exit of the leveling mill frame to accurately measure the entrance and exit speeds of the strip steel. The entrance and exit speeds of the strip steel measured by the laser velocimeter are assumed to be V. S,LActE and V S,LActX .

[0101] The strip speed at the leveler entrance is derived from two sources: the laser velocimeter measurement value V S,LActE and V calculated by the pulse encoder measurement of the entrance tension roller S,PActE There are three sources of strip speed at the exit of the leveler: the laser velocimeter measurement value V S,LActX , V calculated by the pulse encoder of the exit steering roller S,PActX and V calculated by multiplying the frame linear speed by the slip coefficient S,PActS ×S L , where S L The forward slip coefficient value given for the secondary system.

[0102] Laser velocimeters can accurately measure the inlet and outlet speeds of the strip, but they are easily affected by the on-site environment (for example, dust, steam, and leveling fluid can affect the laser velocimeter's measurement accuracy). Laser velocimeters are the preferred speed source. If the laser velocimeter fails or is interfered with, the system automatically switches to measuring the speed using the pulse encoders of the inlet and outlet drive rollers. If the pulse encoder of the outlet steering roller fails or the roller slips, the strip outlet speed calculated by multiplying the frame linear speed by the slip coefficient is automatically selected.

[0103] In some embodiments, step S20 specifically includes:

[0104] S201. When the speed source is switched, the strip speed value is ramped.

[0105] When a change in the speed source is detected, switching directly from one speed to another can impact the control system. A large difference between the two speed values can cause oscillation, affecting the stability of the control system. Therefore, a ramp process is implemented when switching between the two speed values. In this embodiment, the ramp time is set to 500ms, meaning that the strip inlet and outlet speeds ramp from the original value to the new value within 500ms.

[0106] S202. Calculate the initial value of the elongation using the strip entry and exit speeds.

[0107] According to the strip inlet and outlet speed, the initial elongation value E is calculated as follows: Act,ini :

[0108]

[0109] Where V S,Exit and V S,Entry They are the speeds of the strip at the exit and entrance selected in the previous step, and are the values obtained after ramp processing when the speed source is switched.

[0110] S203 , performing a limiting and smoothing process on the initial value of the elongation to obtain an actual value of the elongation.

[0111] The initial value of elongation is limited and smoothed to obtain the actual value of elongation:

[0112] E Act =PT1(LIM(E Act,ini ))

[0113] Where LIM represents the limiting link. In this embodiment, the elongation is limited to the range of [0.99 to 1.15]. PT1 represents the first-order smoothing link. The discrete PT1 algorithm used in the PLC is:

[0114]

[0115] In the above formula, P PT1 (n) is the output value of the first-order smoothing link at time n, P PT1 (n-1) is the output value of the first-order smoothing link at time n-1, T PT1 is the smoothing time of the first-order smoothing link, T S is the sampling time of the PLC controller, and X(n) is the input value of the first-order smoothing link at time n. In this embodiment, T S =8ms.

[0116] In some embodiments, step S30 specifically includes: S301, calculating the adaptive gain according to the strip width and the entrance thickness setting value.

[0117] Calculate the adaptive gain G of the elongation controller according to the actual width of the strip and the set value of the inlet thickness adapt :

[0118]

[0119] Where W Act is the actual width of the strip, W Max is the maximum width of the strip, H EntrySP Set a value for the strip entry thickness.

[0120] S302: Calculate the rolling force of the elongation control integral part.

[0121] The integral controller is used to calculate the integral part of the rolling force for elongation control based on the elongation difference:

[0122]

[0123] Where, F Int is the integral part of the rolling force controlled by the elongation, and F int (n) and F int (n-1) are the values at time n and time n-1 respectively, T E is the integral time parameter of the controller, in this embodiment, T E =500ms, E Set Set a value for the elongation.

[0124] S303. Calculate the elongation-controlled pre-controlled rolling force according to the actual speed of the skin-pass mill stand, and add the integral partial rolling force to obtain the total elongation-controlled rolling force.

[0125]

[0126] Where, F SP,FM is the rolling force setting value during flattening, F SP,Thread The rolling force setting value during strip threading is given by the secondary system. Stand is the actual value of the rack speed, V Thread V is the speed setting value when threading the belt. Max Set the maximum speed.

[0127] The pre-controlled rolling force plus the integral rolling force is the total elongation-controlled rolling force, which is added to the original rolling force setting value to obtain the total rolling force setting value:

[0128] F SP,all =F SP,FM +F Int +F Pc

[0129] The total rolling force set value is sent to the pressure control system of the leveler, and the pressure control system controls the actual value of the rolling force to reach the set value, thereby realizing this high-stability leveler elongation control method.

[0130] This embodiment proposes a highly stable elongation control method for a tempering mill. The method first calculates the strip speeds at the entry, stand, and exit of the tempering mill based on pulse encoder measurements on the entry tension roller, stand drive roller, and exit steering roller. Band-stop filters are used to filter out interference signals from the drive roller rotational frequency. The strip entry and exit speeds are then selected from multiple speed sources based on on-site operating conditions. A ramping process is applied when switching speed sources. The processed strip entry and exit speeds are then used to calculate the initial elongation value, which is then clipped and smoothed to obtain the actual elongation value. An adaptive gain is calculated based on the set values for the strip width and entry thickness, and an integral controller is used to calculate the integral portion of the control rolling force. A pre-controlled rolling force is then calculated based on the actual stand speed, and the total elongation control rolling force is summed. This method utilizes a laser velocimeter and pulse encoder to measure the strip entry and exit speeds. The pulse encoder measurements are filtered to eliminate interference. In the event of equipment failure or interference, the method automatically switches to another speed value calculated using an alternate method. A ramping process is also applied when switching speed sources to ensure a smooth transition. In the process of calculating the rolling force control quantity, a method combining an integral controller with adaptive gain and a pre-controlled rolling force that changes with speed is used to achieve precise control of the elongation of the leveler. It has strong adaptive capabilities and ensures that the elongation can still be accurately and effectively controlled under complex and changeable on-site environments.

[0131] An embodiment of the present invention further provides a highly stable elongation control system for a leveling machine, the system comprising:

[0132] The data acquisition module is used to calculate the strip inlet and outlet speed values using multiple methods and select the strip inlet and outlet speed values from multiple speed sources;

[0133] The elongation calculation module is used to perform ramp processing on the strip speed value when the speed source is switched, calculate the elongation using the processed strip inlet and outlet speeds, and obtain the actual elongation value after limiting and smoothing;

[0134] The control module is used to calculate the adaptive gain according to the set values of strip width and entrance thickness, and use the integral controller to calculate the integral part of the rolling force according to the difference between the elongation set value and the actual elongation value, and then calculate the pre-control rolling force according to the actual speed of the frame. The total rolling force set value is obtained based on the integral part of the rolling force and the pre-control rolling force, and the high-stability elongation control of the leveler is achieved based on the total rolling force set value.

[0135] It should be noted that the embodiments of the present invention can be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. For hardware implementation, the processing unit can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic controllers (PLCs), field programmable gate arrays (FPGAs), processors, controllers, microprocessors, microcontrollers, other electronic units designed to perform the functions described herein, or a combination thereof. When the embodiments are implemented in software, firmware, middleware, or microcode, program code, or code segments, they can be stored in a machine-readable medium such as a storage component.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-stability elongation control method for a leveling mill, characterized in that: The method comprises: Calculate the strip inlet and outlet speed values using multiple methods and select the strip inlet and outlet speed values from multiple speed sources; When the speed source is switched, the strip speed value is ramped, and the elongation is calculated using the processed strip inlet and outlet speeds. The actual elongation value is obtained after limiting and smoothing. The adaptive gain is calculated according to the set values of strip width and entrance thickness, and the integral part of the rolling force is calculated by an integral controller according to the difference between the set value of elongation and the actual value of elongation. The pre-control rolling force is then calculated according to the actual speed of the stand. The total rolling force set value is obtained based on the integral part of the rolling force and the pre-control rolling force. Based on the total rolling force set value, highly stable elongation control of the leveler is achieved.

2. The high-stability elongation control method of a leveling mill according to claim 1, characterized in that: The multiple methods for calculating the strip inlet and outlet speed values specifically include: Pulse encoders are installed on the transmission motors of the entrance tension roller, the transmission roller and the exit steering roller of the leveler frame. The speed values of the strip at the entrance, the frame and the exit are calculated based on the measured values of the pulse encoders. S,PulseE 、V S,PulesS 、V S,PulseX ; The speed signals of the strip at the entrance, rack and exit are filtered out by using a band-stop filter to remove the interference signal of the transmission roller rotation frequency. The speed values of the strip at the entrance, rack and exit after filtering are V and V, respectively. S,PActE 、V S,PActS 、V S,PActX ; Laser velocimeters are installed at the entrance and exit of the leveling mill frame to measure the strip inlet and outlet speeds. The strip inlet and outlet speeds measured by the laser velocimeter are V and V, respectively. S,LActE and V S,LActX ; The strip speed at the leveler entrance is derived from two sources: the laser velocimeter measurement value V S,LActE and V calculated by the pulse encoder measurement of the entrance tension roller S,PActE There are three sources of strip speed at the exit of the leveler: the laser velocimeter measurement value V S,LActX , V calculated by the pulse encoder of the exit steering roller S,PActX and the rack linear velocity V S,PActS Multiply by the slip coefficient S L Calculated V S,PActS ×S L , where S L The forward slip coefficient value given for the secondary system.

3. The high-stability elongation control method of a leveling mill according to claim 2, characterized in that: The method of selecting the strip steel inlet and outlet speed values from a plurality of speed sources specifically includes: The preferred speed source is the laser velocimeter. When the laser velocimeter fails or is disturbed, the system automatically switches to the pulse encoder of the inlet and outlet drive rollers to measure the speed. When the pulse encoder of the outlet steering roller fails or the roller slips, the strip outlet speed calculated by multiplying the frame linear speed by the slip coefficient will be automatically selected.

4. The high-stability elongation control method of a leveler according to claim 2, characterized in that: The speed of the strip at the corresponding position of the skin-pass mill is calculated based on the pulse encoder measurement value, where the corresponding positions include the entrance, frame, and exit. The formula is as follows: V S,Pulse =N Pulse ×G EM ×π×(D R +0.5h s ) Where N Pluse is the motor speed of the corresponding roller at the corresponding position measured by the pulse encoder, G EM is the gear ratio of the motor, D R is the diameter of the corresponding roller, h s is the strip thickness at the corresponding roller position.

5. The high-stability elongation control method of a skin-pass mill according to claim 4, characterized in that: The speed signal at the corresponding position of the strip is filtered out using a band-stop filter to remove the interference signals of the transmission roller rotation frequency, including: The signals of the single frequency and double frequency of the corresponding roller rotation at the corresponding position are filtered out from the calculated strip speed by using a band-stop filter to obtain the actual value of the strip speed at the corresponding position after filtering.

6. The high-stability elongation control method of a skin-pass mill according to claim 5, characterized in that: The actual value of strip speed V after filtering at the corresponding position S,PAct The calculation formula is as follows: In S,PAct =BSF(V S,Pulse ) Where BSF represents the band-stop filter, and the transfer function of the analog band-stop filter is: Where A F is the filter gain, T A is the PLC sampling time, F stop is the blocking frequency, j is the unit representing the imaginary number in Laplace transform, and BW is the bandwidth.

7. The high-stability elongation control method of a skin-pass mill according to claim 1, characterized in that: The process of performing ramp processing on the strip speed value when the speed source is switched, calculating the elongation using the processed strip inlet and outlet speeds, and obtaining the actual elongation value after limiting and smoothing the processed strip speeds specifically includes: When a change in the speed source is detected, ramp processing is performed when switching between two speed values, that is, when the speed is switched, the speed value ramps from the original value to the new value within a certain period of time; Calculate the initial value of elongation E according to the strip inlet and outlet speed Act,ini , the formula is as follows: Where V S,Exit and V S,Entry are the values of the strip speed at the exit and entrance after the ramp processing when the speed source is switched; The initial value of elongation is limited and smoothed to obtain the actual value of elongation. The formula is as follows: AND Act =PT1(LIM(E Act,ini )) Where LIM represents the limiting link, PT1 represents the first-order smoothing link, and the discrete PT1 algorithm used in PLC is: Where, P PT1 (n) is the output value of the first-order smoothing link at time n, P PT1 (n-1) is the output value of the first-order smoothing link at time n-1, T PT1 is the smoothing time of the first-order smoothing link, T S is the sampling time of the PLC controller, and x(n) is the input value of the first-order smoothing link at time n.

8. The high-stability elongation control method of a skin-pass mill according to claim 1, characterized in that: The adaptive gain is calculated according to the set values of the strip width and the inlet thickness, and the integral controller is used to calculate the integral part to control the rolling force. The pre-controlled rolling force is then calculated according to the actual speed of the stand, and the total rolling force set value is obtained by adding them together. The high-stability elongation control of the skin-pass mill based on the total rolling force set value specifically includes: Calculate the adaptive gain G of the elongation controller according to the set values of strip width and inlet thickness adapt : Where W Act is the actual width of the strip, W Max is the maximum width of the strip, H EntrySP Set the value for the strip entrance thickness; Calculate the rolling force for the integral part of elongation control: The integral controller is used to calculate the integral part of the rolling force for elongation control based on the elongation difference: Where, E Act is the actual value of elongation, F Int is the integral part of the rolling force controlled by the elongation, and F int (n) and F int (n-1) are the values at time n and time n-1 respectively, T E is the integral time parameter of the controller, E Set Set a value for the elongation; The elongation control pre-controlled rolling force is calculated based on the actual speed of the skin-pass mill stand, and the total elongation control rolling force is obtained by adding the integral partial rolling force; Where, F SP,FM is the rolling force setting value during flattening, F SP,Thread The rolling force setting value during strip threading is given by the secondary system. Stand is the actual value of the rack speed, V Thread V is the speed setting value when threading the belt. Max is the maximum speed setting value; The pre-controlled rolling force plus the integral rolling force is the total elongation-controlled rolling force, which is added to the original rolling force setting value to obtain the total rolling force setting value: F SP,all =F SP,FM +F Int +F Pc The total rolling force set value is sent to the pressure control system of the leveler, and the pressure control system controls the actual rolling force value to reach the total rolling force set value, thereby achieving high-stability elongation control of the leveler.

9. A high-stability elongation control system for a leveling mill, characterized in that: The system comprises: The data acquisition module is used to calculate the strip inlet and outlet speed values using multiple methods and select the strip inlet and outlet speed values from multiple speed sources; The elongation calculation module is used to perform ramp processing on the strip speed value when the speed source is switched, calculate the elongation using the processed strip inlet and outlet speeds, and obtain the actual elongation value after limiting and smoothing; The control module is used to calculate the adaptive gain according to the set values of strip width and entrance thickness, and use the integral controller to calculate the integral part of the rolling force according to the difference between the elongation set value and the actual elongation value, and then calculate the pre-control rolling force according to the actual speed of the frame. The total rolling force set value is obtained based on the integral part of the rolling force and the pre-control rolling force, and the high-stability elongation control of the leveler is achieved based on the total rolling force set value.

10. The high-stability elongation control system for a skin-pass mill according to claim 9, characterized in that: The adaptive gain is calculated according to the set values of the strip width and the inlet thickness, and the integral controller is used to calculate the integral part to control the rolling force. The pre-controlled rolling force is then calculated according to the actual speed of the stand, and the total rolling force set value is obtained by adding them together. The high-stability elongation control of the skin-pass mill based on the total rolling force set value specifically includes: Calculate the adaptive gain G of the elongation controller according to the set values of strip width and inlet thickness adapt : Where W Act is the actual width of the strip, W Max is the maximum width of the strip, H EntrySP Set the value for the strip entrance thickness; Calculate the rolling force for the integral part of elongation control: The integral controller is used to calculate the integral part of the rolling force for elongation control based on the elongation difference: Where, E Act is the actual value of elongation, F Int is the integral part of the rolling force controlled by the elongation, and F int (n) and F int (n-1) are the values at time n and time n-1 respectively, T E is the integral time parameter of the controller, E Set Set a value for the elongation; The elongation control pre-controlled rolling force is calculated based on the actual speed of the skin-pass mill stand, and the total elongation control rolling force is obtained by adding the integral partial rolling force; Where, F SP,FM is the rolling force setting value during flattening, F SP,Thread The rolling force setting value during strip threading is given by the secondary system. Stand is the actual value of the rack speed, V Tread V is the speed setting value when threading the belt. Max is the maximum speed setting value; The pre-controlled rolling force plus the integral rolling force is the total elongation-controlled rolling force, which is added to the original rolling force setting value to obtain the total rolling force setting value: F SP,all =F SP,FM +F Int +F Pc The total rolling force set value is sent to the pressure control system of the leveler, and the pressure control system controls the actual rolling force value to reach the total rolling force set value, thereby achieving high-stability elongation control of the leveler.

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