A method for inter-stand tension control in endless continuous casting and rolling of strip steel

Abstract

This invention relates to a method for inter-stand tension control in continuous casting and rolling of strip steel, comprising: establishing tension in the target looper between target stands; acquiring the actual tension feedback value of the target looper, comparing the actual tension feedback value with the tension set value of the target looper, determining whether the inter-stand tension control meets the standard, and if it does, ending the current round of tension control; if it does not meet the standard, identifying the target mill to be adjusted, adjusting the main speed of the target mill according to the comparison between the actual tension feedback value and the tension set value, and cyclically executing S2 to S3 until the inter-stand tension control meets the standard; if the tailing condition of the inlet mill is not activated, the target mill is identified as the outlet mill; if the tailing condition of the inlet mill is activated, the target mill is identified as the inlet mill. In this invention, the method of adjusting the inter-stand tension by adjusting the main speed of the mill, and determining whether to use the pre-tension control mode or the post-tension control mode by whether the mill enters the tailing condition, ensures that the inter-stand tension can better match the normal production conditions and the tailing condition, ensuring stable rolling of strip steel during continuous production, thereby improving product quality.

Description

Technical Field

[0001] This invention belongs to the field of continuous casting and rolling technology for strip steel, specifically relating to a method for controlling interstand tension in continuous casting and rolling of strip steel. Background Technology

[0002] The continuous casting and rolling process for strip steel has advantages such as simplified process, shorter production flow, fewer equipment, energy saving, and high yield. It can be more flexible in responding to the market and is an important direction for the development of hot-rolled strip steel production technology.

[0003] In the continuous casting and rolling process of strip steel, the control of looper tension is one of the key factors in ensuring strip steel quality and production efficiency. Because the upstream and downstream systems are highly interconnected in the continuous casting and rolling process, with the entire strip production running from the continuous casting machine to the coiler, and the produced strip being thinner, the requirements for rapid tension response and stability are much higher to ensure stable rolling of the strip during continuous production and guarantee product quality. However, traditional hot continuous rolling looper tension control, both in terms of equipment structure and control strategies, is no longer suitable for the needs of continuous casting and rolling of strip steel. Summary of the Invention

[0004] This invention relates to a method for controlling the tension between stands in continuous casting and rolling of strip steel, which can at least solve some of the defects of the prior art.

[0005] This invention relates to a method for inter-stand tension control in continuous casting and rolling of strip steel, comprising,

[0006] S1, target looper setup between target racks;

[0007] S2, obtain the actual tension feedback value F0 of the target looper, and compare the actual tension feedback value F0 with the tension set value SP of the target looper. W Compare the results to determine whether the tension control between the racks meets the standards;

[0008] S3, if the tension control between stands meets the standard, then end the current round of tension control; if it does not meet the standard, then determine the target mill to be adjusted, adjust the main speed of the target mill according to the comparison between the actual tension feedback value and the tension set value, and repeat S2~S3 until the tension control between stands meets the standard.

[0009] The method for determining the target mill is as follows: determine whether the tailing condition of the inlet mill between the target stands is activated. If the tailing condition of the inlet mill is not activated, the target mill is determined to be the outlet mill between the target stands. If the tailing condition of the inlet mill is activated, the target mill is determined to be the inlet mill.

[0010] As one implementation method, in S3, a proportional-integral control method is used to adjust the main speed of the target rolling mill, specifically including:

[0011] Calculate the proportional coefficients KP1, KP2, and KP3, and obtain the main speed adjustment amount ΔY through the proportional-integral controller, where ΔY = KP1 + KP2 + KP3. Based on the obtained main speed adjustment amount, adjust the main speed of the target rolling mill.

[0012] The calculation method for KP1 is as follows: obtain the starting signal Boost_active of the target looper. When Boost_active=1, KP1=C1×the current main speed of the target mill, where C1 is an empirical constant; when Boost_active=0, KP1=0.

[0013] The calculation method for KP2 is as follows: When the target mill is the inlet mill, KP2 = C2 × (F0 - SP) W When the target mill is an exit mill, KP2 = C2 × (SP) W -F0); C2 is an empirical constant;

[0014] The calculation method for KP3 is as follows: when the target mill is the inlet mill, When the target mill is an export mill, C3 is an empirical constant.

[0015] As one implementation method, the method for obtaining the actual tension feedback value F0 includes:

[0016] Pressure sensors are configured on both the drive-side and operation-side drive units of the target looper to detect the vertical pressure on the looper rollers.

[0017] The formula for calculating F0 is as follows:

[0018]

[0019] Among them, h1 and These are the strip thickness and strip width at the exit of the inlet mill, respectively; F T The net tension value of the strip at the target looper is expressed in N; F0 is expressed in N / m. 2 .

[0020] As one of the implementation methods, F T The following formula is used for calculation:

[0021]

[0022] In the formula:

[0023] F TR These are measured values ​​from a single-sided pressure sensor.

[0024] F m The weight of the strip steel applied to a single-sided drive unit, m strip For strip steel quality;

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] Among them, h L ΔPL1 and ΔPL2 are the pass-through heights of the inlet and outlet mills, respectively; h1 and h2 are the strip thicknesses at the outlet of the inlet and outlet mills, respectively; r is the radius of the looper roll; l1 is the distance between the centerline of the looper roll and the outlet of the inlet mill; and l2 is the distance between the centerline of the looper roll and the outlet of the outlet mill.

[0036] As one implementation method, the tension setting value SP W Calculate using the following formula:

[0037]

[0038] Among them, SP start and SP aim These are the initial tension setting value and the target tension setting value of the target looper, respectively; the value of w is between 0 and 1, representing the proportion of the strip length exiting the rolling mill.

[0039] As one implementation method, SP start and SP aim It was calculated using the tension model in the secondary machine.

[0040] As one implementation method, the method for determining the tail-wagging condition of the inlet rolling mill includes:

[0041] The position of the strip tail is detected. When the distance between the strip tail and the entrance mill is greater than a set threshold, the entrance mill is in an inactive tail-swing mode. When the distance between the strip tail and the entrance mill is less than or equal to the set threshold, the entrance mill is activated for tail-swing mode.

[0042] As one of the implementation methods, in S1, when the exit mill bite signal between the target stands is triggered, the target looper is raised to a set height; then the target looper continues to rise until the pressure of the strip on the target looper reaches a preset value, at which point the tension establishment stage is completed.

[0043] As one implementation method, the inter-rack tension control method further includes:

[0044] After this round of tension control is completed, the strip tension between the target frames is continuously monitored. When the strip tension between the target frames exceeds the set range, the next round of tension control is performed.

[0045] The present invention has at least the following beneficial effects:

[0046] In this invention, the tension between stands is adjusted by regulating the main speed of the rolling mill. The method of using the front tension control mode or the rear tension control mode is determined by whether the rolling mill enters the tailing condition. This ensures that the tension between stands can better match the normal production conditions and the tailing condition, and ensures that the strip can be rolled stably during continuous production, thereby improving product quality. Attached Figure Description

[0047] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A schematic flowchart of the inter-rack tension control method provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the loop structure;

[0050] Figure 3 A schematic diagram of proportional-integral control logic provided for an embodiment of the present invention;

[0051] Figure 4 and Figure 5 This is a schematic diagram illustrating the process of calculating the actual tension feedback value F0. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 are within the scope of protection of the present invention.

[0053] like Figure 1 This invention provides a method for tension control between stands in a continuous casting and rolling mill for strip steel. In the continuous casting production line for strip steel, loopers are mainly arranged between the stands of the finishing mill.

[0054] The above-mentioned inter-rack tension control methods include,

[0055] S1, target looper setup between target racks;

[0056] S2, obtain the actual tension feedback value F0 of the target looper, and compare the actual tension feedback value F0 with the tension set value SP of the target looper. W Compare the results to determine whether the tension control between the racks meets the standards;

[0057] S3, if the tension control between stands meets the standard, then end the current round of tension control; if it does not meet the standard, then determine the target mill to be adjusted, adjust the main speed of the target mill according to the comparison between the actual tension feedback value and the tension set value, and repeat S2~S3 until the tension control between stands meets the standard.

[0058] The method for determining the target mill is as follows: determine whether the tailing condition of the inlet mill between the target stands is activated. If the tailing condition of the inlet mill is not activated, the target mill is determined to be the outlet mill between the target stands. If the tailing condition of the inlet mill is activated, the target mill is determined to be the inlet mill.

[0059] Understandably, a stand is defined by the aforementioned inlet and outlet mills, wherein the inlet mill is located upstream of the outlet mill, and the looper is arranged between the inlet and outlet mills.

[0060] In a finishing mill, strip tension is divided into front tension and back tension. Front tension is also called mill exit tension, while back tension is mill inlet tension. For tension control between a specific target stand, the strip tension between the target stands corresponds to the front tension at the inlet mill and the back tension at the outlet mill. In this embodiment, the tension between stands is adjusted by regulating the main speed of the mill. Whether to use front tension control mode or back tension control mode is determined by whether the mill enters the tailing condition. This ensures that the tension between stands can better match normal production conditions and tailing conditions, ensuring stable rolling of the strip during continuous production, thereby improving product quality.

[0061] In this embodiment, under normal production conditions, a post-tension control mode is adopted, while under tailing conditions, a pre-tension control mode is adopted. In the continuous casting and rolling process of ultra-thin strip steel, since the rolled piece is relatively long, the tailing time only accounts for a small portion. The above-mentioned tension control method can ensure the accuracy of strip tension control between stands. For a certain target stand, when the post-tension control mode is matched, it corresponds to the normal production condition. At this time, the exit mill is determined as the target mill, and the tension between the target stands is controlled by adjusting the main speed of the exit mill. When the pre-tension control mode is matched, it corresponds to the tailing condition of the inlet mill. At this time, the inlet mill is determined as the target mill, and the tension between the target stands is controlled by adjusting the main speed of the inlet mill. By judging whether the tailing condition of the inlet mill is activated, it can be determined whether the target stand should be matched under normal production conditions or tailing conditions.

[0062] Optionally, the methods for determining the tail-off condition of the rolling mill include:

[0063] The position of the strip tail is detected. When the distance between the strip tail and the entrance mill is greater than a set threshold, the entrance mill is in an inactive tail-swing mode. When the distance between the strip tail and the entrance mill is less than or equal to the set threshold, the entrance mill's tail-swing mode is activated. Therefore, whether the entrance mill has entered the tail-swing mode can be determined by the above method. In one embodiment, the set threshold is selected within the range of 2 to 3 meters, for example, set to 2.5 meters.

[0064] In one embodiment, in S1, when the exit mill bite signal between the target stands is triggered, the target looper is raised to a set height; then the target looper continues to rise until the pressure of the strip on the target looper reaches a preset value, at which point the tension building stage is completed.

[0065] Preferably, the height deviation is obtained by detecting the real-time movement height of the looper roller 11 and comparing it with the target height setting value; the drive unit of the target looper is controlled based on the height deviation value, so that the target looper can be quickly lifted and reach the specified height. In this way, closed-loop control of the looper height is realized.

[0066] The looper's drive unit includes, but is not limited to, a hydraulic cylinder 12. Generally, the looper is configured with a transmission-side drive unit and an operating-side drive unit, and both the transmission-side drive unit and the operating-side drive unit can be hydraulic cylinders 12. This includes, but is not limited to, equipping the hydraulic cylinder guide rod 121 with a displacement sensor to detect the real-time movement height of the looper roller 11 by detecting the amount of travel of the hydraulic cylinder guide rod 121.

[0067] In one embodiment, the tension setpoint SP WCalculate using the following formula:

[0068]

[0069] Among them, SP start and SP aim These are the initial tension setting value and the target tension setting value of the target looper, respectively; the value of w is between 0 and 1, representing the proportion of the strip length exiting the rolling mill.

[0070] Among them, SP start and SP aim The values ​​can be sent in real time by the secondary machine, and can be manually set or calculated by the tension model in the secondary machine.

[0071] In one embodiment, the method for obtaining the actual tension feedback value F0 includes:

[0072] like Figure 2 Pressure sensors 13 are respectively configured on the transmission-side drive unit and the operation-side drive unit of the target looper to detect the vertical pressure on the looper roller 11. The pressure sensors 13 can be set between the output end of the drive unit and the looper roller 11, for example, between the hydraulic cylinder guide rod 121 and the looper roller 11. Alternatively, an oil pressure sensor can be configured on the input oil line of the hydraulic cylinder 12 to calculate the thrust of the hydraulic cylinder 12. This sensor can serve as a backup for the pressure sensors 13, or work together to calculate the vertical pressure on the looper roller 11, thereby improving data accuracy.

[0073] The formula for calculating F0 is as follows:

[0074]

[0075] Among them, h1 and These are the strip thickness and strip width at the exit of the inlet mill, respectively; F T The net tension value of the strip at the target looper is expressed in N; F0 is expressed in N / m. 2 .

[0076] Furthermore, such as Figure 4 and Figure 5 F T The following formula is used for calculation:

[0077]

[0078] In the formula:

[0079] F TR This is the measured value of the single-sided pressure sensor 13;

[0080] F mThe weight of the strip steel applied to a single-sided drive unit, m strip For strip steel quality;

[0081] horn and For details on the meaning of the relevant calculation parameters, please refer to [link / reference]. Figure 5 The calculation formula is as follows:

[0082]

[0083]

[0084] Furthermore, the other parameters are calculated as follows:

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] Among them, h L ΔPL1 and ΔPL2 are the passing line heights of the inlet and outlet mills, respectively; h1 and h2 are the strip thicknesses at the outlet of the inlet and outlet mills, respectively; r is the radius of the looper roll 11; l1 is the distance between the centerline of the looper roll 11 and the outlet of the inlet mill; and l2 is the distance between the centerline of the looper roll 11 and the outlet of the outlet mill.

[0094] The actual tension feedback value F0 can be accurately calculated using the above method.

[0095] In one embodiment, such as Figure 3 In S3, the proportional-integral control method is used to adjust the main speed of the target rolling mill, specifically including:

[0096] Calculate the proportional coefficients KP1, KP2, and KP3, and obtain the main speed adjustment amount ΔY through the proportional-integral controller, where ΔY = KP1 + KP2 + KP3. Based on the obtained main speed adjustment amount, adjust the main speed of the target rolling mill.

[0097] The calculation method for KP1 is as follows: obtain the starting signal Boost_active of the target looper. When Boost_active=1, KP1=C1×the current main speed of the target mill, where C1 is an empirical constant; when Boost_active=0, KP1=0.

[0098] The calculation method for KP2 is as follows: When the target mill is the inlet mill, KP2 = C2 × (F0 - SP) W When the target mill is an exit mill, KP2 = C2 × (SP) W -F0); C2 is an empirical constant;

[0099] The calculation method for KP3 is as follows: when the target mill is the inlet mill, When the target mill is an export mill, C3 is an empirical constant.

[0100] exist Figure 3 In the middle, Set1 corresponds to the initial tension setting value SP. start [N / m 2 ] / [m];

[0101] Set2 corresponds to the target tension setpoint SP. aim [N / m 2 ] / [m];

[0102] X* corresponds to the actual tension feedback value F0, [N / m] 2 ] / [m];

[0103] w represents the proportion of the strip length exiting the rolling mill;

[0104] V is the actual value of the main speed of the rolling mill, in m / s;

[0105] Ti is the integral time of the PI control.

[0106] Based on the above scheme, factors such as the main speed of the target mill and the real-time strip tension between the target stands are fully considered, and the main speed adjustment can be accurately calculated to ensure the accuracy of tension adjustment between stands.

[0107] More preferably, the inter-rack tension control method further includes:

[0108] After this round of tension control is completed, the strip tension between the target frames is continuously monitored. When the strip tension between the target frames exceeds the set range, the next round of tension control is performed.

[0109] 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 within the protection scope of the present invention.

Claims

1. A method for controlling inter-stand tension in continuous casting and rolling of strip steel, characterized in that, include, S1, target looper setup between target racks; S2, obtain the actual tension feedback value F0 of the target looper, and compare the actual tension feedback value F0 with the tension set value SP of the target looper. W Compare the results to determine whether the tension control between the racks meets the standards; S3, if the tension control between racks meets the standard, then end this round of tension control; If the target is not met, the target mill to be adjusted is determined, and the main speed of the target mill is adjusted according to the comparison between the actual tension feedback value and the tension set value. S2~S3 are executed repeatedly until the tension control between the stands meets the target. The method for determining the target mill is as follows: determine whether the tailing condition of the inlet mill between the target stands is activated. If the tailing condition of the inlet mill is not activated, the target mill is determined to be the outlet mill between the target stands. If the tailing condition of the inlet mill is activated, the target mill is determined to be the inlet mill. In S3, the proportional-integral control method is used to adjust the main speed of the target mill, specifically including: Calculate the proportional coefficients KP1, KP2, and KP3, and obtain the main speed adjustment amount ΔY through the proportional-integral controller, where ΔY = KP1 + KP2 + KP3. Based on the obtained main speed adjustment amount, adjust the main speed of the target rolling mill. The calculation method for KP1 is as follows: obtain the starting signal Boost_active of the target looper. When Boost_active=1, KP1=C1×the current main speed of the target mill, where C1 is an empirical constant; when Boost_active=0, KP1=0. The calculation method for KP2 is as follows: When the target mill is the inlet mill, KP2 = C2 × (F0 - SP) W When the target mill is an exit mill, KP2 = C2 × (SP) W -F0); C2 is an empirical constant; The calculation method for KP3 is as follows: when the target mill is the inlet mill, When the target mill is an export mill, C3 is an empirical constant.

2. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 1, characterized in that, The method for obtaining the actual tension feedback value F0 includes: Pressure sensors are configured on both the drive-side and operation-side drive units of the target looper to detect the vertical pressure on the looper rollers. The formula for calculating F0 is as follows: Among them, h1 and These are the strip thickness and strip width at the exit of the inlet mill, respectively; F T The net tension value of the strip at the target looper is expressed in N; F0 is expressed in N / m. 2 ; F T The following formula is used for calculation: In the formula: F TR These are measured values ​​from a single-sided pressure sensor. F m The weight of the strip steel applied to a single-sided drive unit, m strip For strip steel quality; Among them, h L ΔPL1 and ΔPL2 are the pass-through heights of the inlet and outlet mills, respectively; h1 and h2 are the strip thicknesses at the outlet of the inlet and outlet mills, respectively; r is the radius of the looper roll; l1 is the distance between the centerline of the looper roll and the outlet of the inlet mill; and l2 is the distance between the centerline of the looper roll and the outlet of the outlet mill.

3. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 1, characterized in that, The tension setting value SP W Calculate using the following formula: Among them, SP start and SP aim These are the initial tension setting value and the target tension setting value of the target looper, respectively; the value of w is between 0 and 1, representing the proportion of the strip length exiting the rolling mill.

4. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 3, characterized in that, SP start and SP aim It was calculated using the tension model in the secondary machine.

5. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 1, characterized in that, The methods for determining the tail-off condition of the inlet rolling mill include: The position of the strip tail is detected. When the distance between the strip tail and the entrance mill is greater than a set threshold, the entrance mill is in an inactive tail-swing mode. When the distance between the strip tail and the entrance mill is less than or equal to the set threshold, the entrance mill is activated for tail-swing mode.

6. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 1, characterized in that, In S1, when the strip bite signal of the exit mill between the target stands is triggered, the target looper is raised to the set height; then the target looper continues to rise until the pressure of the strip on the target looper reaches the preset value, at which point the tension establishment stage is completed.

7. The inter-stand tension control method for endless continuous casting and rolling of strip steel as described in claim 1, characterized in that, The inter-rack tension control method further includes: After this round of tension control is completed, the strip tension between the target frames is continuously monitored. When the strip tension between the target frames exceeds the set range, the next round of tension control is performed.

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