Bending roll force control method for hot rolling finishing roll back pressure system

Abstract

The present invention discloses a method for controlling the bending force of a hot rolling finishing roll back pressure system. The method is used for a hot rolling finishing mill equipped with a bending roll back pressure system, and includes: determining a bending force setting reference value according to the type of steel being rolled; determining the number of bending cylinders currently in operation at the finishing mill frame, the cross-sectional area of ​​the rodless cavity, the cross-sectional area of ​​the rodless cavity, and the pressure of the rodless cavity, as well as the back pressure input by the bending roll back pressure system; calculating the rodless cavity bending force and the back pressure compensation bending force according to the bending cylinder parameter information and the back pressure; calculating the actual bending force after back pressure compensation based on the rodless cavity bending force and the back pressure compensation bending force, and performing bending force control based on the determined actual bending force after back pressure compensation and the bending force setting reference value. The present invention can take into account the influence of the back pressure after increasing the bending roll back pressure system, avoid abnormal strip shape problems during strip rolling, reduce abnormal downtime, and improve strip shape quality.

Description

Technical Field

[0001] The present invention relates to the technical field of hot rolling equipment control, and in particular to a method for controlling the bending force of a hot rolling finishing bending roll back pressure system. Background Art

[0002] Hot-rolled strip steel occupies an important position in the entire industrial system. The strip shape is a key indicator to measure whether the quality of hot-rolled strip steel products is qualified. Strip shape control is an important technology in strip steel production.

[0003] In traditional hot-rolled finishing roll bending systems, the rod chamber of the bending roll hydraulic cylinder is pressure-free during rolling. However, due to the frequent movement of the piston rod, a loose seal on the piston rod can cause roll cooling water to enter the hydraulic system, severely contaminating the hydraulic oil circuit and even rendering the hydraulic system inoperable. This can damage a large amount of hydraulic equipment and cause production stoppages on the rolling line. To address this issue, a backpressure system is currently being added to the rod chamber side of the bending roll hydraulic cylinder. In actual use, the backpressure system's backpressure pressure is determined based on the rack cooling water pressure and applied to the bending roll hydraulic cylinder to prevent roll cooling water from entering the hydraulic system and contaminating the hydraulic oil circuit.

[0004] However, by adding a back pressure system on the rod cavity side of the bending roll hydraulic cylinder to provide back pressure, although the roller cooling water can be avoided from entering the hydraulic system, in the actual strip rolling process, the applied back pressure will affect the strip rolling, resulting in abnormal strip shape control, a large number of plate shape quality objections, and seriously affecting the normal production of the hot rolling line. Summary of the Invention

[0005] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a method for controlling the bending roll force of a hot rolling finishing bending roll back pressure system.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for controlling the bending force of a hot rolling finishing rolling bending roll back pressure system is provided. The method is used for a hot rolling finishing rolling mill equipped with a bending roll back pressure system, comprising:

[0008] Determine the reference value for the bending roll force according to the type of steel strip being rolled;

[0009] Determine the number of roll bending cylinders put into use, the cross-sectional area of ​​the rodless cavity, the cross-sectional area of ​​the rodded cavity and the pressure of the rodless cavity, as well as the back pressure put into use by the roll bending back pressure system at the current finishing mill stand;

[0010] Calculate the rodless cavity bending force and back pressure compensation bending force according to the bending cylinder parameter information and back pressure;

[0011] According to the rodless cavity bending roll force and the back pressure compensation bending roll force, the actual bending roll force after back pressure compensation is calculated, and the bending roll force is controlled based on the determined actual bending roll force after back pressure compensation and the bending roll force setting reference value.

[0012] In some possible implementations, the rodless cavity bending roll force is calculated using the following formula:

[0013] W p =P p ×A p ×m

[0014] Among them, W p Indicates the rodless cavity bending roller force, P p Indicates the rodless chamber pressure of the bending roller cylinder, A p It represents the cross-sectional area of ​​the rodless cavity of the bending roll cylinder, and m represents the number of bending roll cylinders put into use.

[0015] In some possible implementations, the back pressure compensation bending roll force is calculated using the following formula:

[0016] W r =F r ×A r ×m

[0017] Among them, W r Indicates the back pressure compensation bending roll force, F r Indicates back pressure, A r It represents the cross-sectional area of ​​the rod cavity of the bending roller cylinder, and m represents the number of bending roller cylinders put into use.

[0018] In some possible implementations, the actual bending roll force after back pressure compensation is calculated using the following formula:

[0019] W a =W p -W r

[0020] Among them, W a Indicates the actual bending roll force after back pressure compensation.

[0021] In some possible implementations, performing roll bending force control based on the determined actual roll bending force after back pressure compensation and the roll bending force setting reference value includes:

[0022] According to the actual bending roll force after back pressure compensation and the bending roll force setting reference value, the given output of the bending roll servo valve is calculated and controlled in real time to control the bending roll force of the bending roll cylinder.

[0023] In some possible implementations, the given output of the bending roll servo valve is calculated using the following formula:

[0024] S n =Sn-1 +K P ×{(1+T A / T N )×ΔW n -ΔW n-1}

[0025] Among them, S n Indicates the given output of the bending roll servo valve at the nth sampling moment, S n-1 K represents the given output of the bending roll servo valve at the n-1th sampling moment. P represents the proportionality coefficient, T A Indicates the scan time, T N Indicates the integration time, ΔW n Indicates the bending roll force difference at the nth sampling moment, ΔW n-1 Indicates the bending roll force difference at the n-1th sampling moment, ΔW n =W ref, -W a, , W ref, Indicates the reference value of the bending roll force at the nth sampling moment, W a, Indicates the actual bending roll force after back pressure compensation at the nth sampling moment.

[0026] In some possible implementations, the method is used for bending roll force control at stands F1 to F7 of a hot rolling finishing mill group.

[0027] The main advantages of the technical solution of the present invention are as follows:

[0028] The bending roll force control method of the hot rolling finishing bending roll back pressure system of the present invention can take into account the influence of the back pressure after increasing the bending roll back pressure system, avoid abnormal strip shape problems such as strip head crushing and tail swinging caused by unstable bending roll force control during strip rolling, reduce abnormal downtime, and improve the plate shape control stability and plate shape quality during strip rolling. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the embodiments of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 The present invention is a flowchart of a method for controlling the bending roll force of a hot rolling finishing rolling bending roll back pressure system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0032] The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0033] See also Figure 1 An embodiment of the present invention provides a method for controlling the bending roll force of a hot rolling finishing rolling bending roll back pressure system. The method is used for a hot rolling finishing rolling mill equipped with a bending roll back pressure system and is implemented by a control system of the finishing rolling mill. The method includes the following steps:

[0034] Step S1, determining a reference value for setting the bending roll force according to the type of steel strip being rolled;

[0035] In the actual rolling production process of strip steel, corresponding bending roll force benchmarks need to be set for different steel types of strip steel, and bending roll force control is performed based on the set bending roll force benchmark to ensure the plate quality of the rolled strip steel.

[0036] In one embodiment of the present invention, according to the steel type of the currently rolled strip, a bending roll force setting reference value corresponding to the currently rolled strip is determined from pre-set bending roll force setting references corresponding to different steel types.

[0037] Step S2, determining the number of roll bending cylinders at the current finishing mill stand, the cross-sectional area of ​​the rodless cavity, the cross-sectional area of ​​the rodless cavity, and the pressure of the rodless cavity, as well as the back pressure of the roll bending back pressure system;

[0038] Specifically, taking a seven-stand hot-rolling finishing mill as an example, this bending force control method is applied to the bending force control of stands F1 to F7 in the hot-rolling finishing mill. When applied to the bending force control of the stands in the hot-rolling finishing mill, the number of bending cylinders in operation, the cross-sectional area of ​​the rodless chamber, the cross-sectional area of ​​the rodless chamber, and the pressure of the rodless chamber, as well as the backpressure applied by the bending backpressure system, must be determined in order to implement subsequent bending force calculation and control.

[0039] In one embodiment of the present invention, the back pressure input by the bending roll back pressure system is determined according to the water pressure of the unit roll cooling water. In order to ensure that the cooling water does not enter the hydraulic system of the unit through the bending roll cylinder, the back pressure input needs to be greater than or equal to the water pressure of the unit roll cooling water.

[0040] Step S3, calculating the rodless cavity roll bending force and the back pressure compensation roll bending force according to the parameter information and back pressure of the roll bending cylinder;

[0041] In one embodiment of the present invention, the rodless cavity bending roll force is calculated using the following formula:

[0042] W p =P p ×A p ×m

[0043] Among them, W p Indicates the rodless cavity bending roller force, P p Indicates the rodless chamber pressure of the bending roller cylinder, A p It represents the cross-sectional area of ​​the rodless cavity of the bending roll cylinder, and m represents the number of bending roll cylinders put into use.

[0044] In one embodiment of the present invention, the back pressure compensation bending roll force is calculated using the following formula:

[0045] W r =F r ×A r ×m

[0046] Among them, W r Indicates the back pressure compensation bending roll force, F r Indicates back pressure, A r It represents the cross-sectional area of ​​the rod cavity of the bending roller cylinder, and m represents the number of bending roller cylinders put into use.

[0047] Step S4, calculating the actual bending roll force after back pressure compensation according to the rodless cavity bending roll force and the back pressure compensation bending roll force, and performing bending roll force control based on the determined actual bending roll force after back pressure compensation and the bending roll force setting reference value.

[0048] In one embodiment of the present invention, the actual bending roll force after back pressure compensation is calculated using the following formula:

[0049] W a =W p -W r

[0050] Among them, W a Indicates the actual bending roll force after back pressure compensation.

[0051] Furthermore, in one embodiment of the present invention, the roll bending force is controlled based on the actual roll bending force after back pressure compensation and the roll bending force setting reference value, including:

[0052] According to the actual bending roll force after back pressure compensation and the bending roll force setting reference value, the given output of the bending roll servo valve is calculated and controlled in real time to control the bending roll force of the bending roll cylinder.

[0053] Since in the hot rolling finishing mill group, the bending force of the bending cylinder is adjusted and controlled by adjusting the output of the corresponding bending servo valve in the hydraulic system, in one embodiment of the present invention, the bending force of the bending cylinder is controlled by real-time calculation and control of the given output of the bending servo valve.

[0054] Specifically, according to the actual bending roll force after back pressure compensation and the bending roll force setting reference value, the given output of the bending roll servo valve is calculated using the following formula:

[0055] S n =S n-1 +K P ×{(1+T A / T N )×ΔW n -ΔW n-1}

[0056] Among them, S n Indicates the given output of the bending roll servo valve at the nth sampling moment, S n-1 K represents the given output of the bending roll servo valve at the n-1th sampling moment. P represents the proportionality coefficient, T A Indicates the scan time, T N Indicates the integration time, ΔW n Indicates the bending roll force difference at the nth sampling moment, ΔW n-1 Indicates the bending roll force difference at the n-1th sampling moment, ΔW n =W ref, -W a, , W ref, Indicates the reference value of the bending roll force at the nth sampling moment, W a, Indicates the actual bending roll force after back pressure compensation at the nth sampling moment.

[0057] In one embodiment of the present invention, the proportional coefficient, scanning time and integration time can be set according to actual conditions. For example, the proportional coefficient can be 2.0*10 -6 ~5.0*10 -6 , the scanning time can be 2 to 10 ms, and the integration time can be 600 to 1000 ms.

[0058] To make the above technical solution of the present invention clearer, the technical solution of the present invention will be described clearly and completely with reference to examples. Obviously, the examples described are only part of the embodiments of the present invention, not all of them.

[0059] Example 1

[0060] Take the F3 frame of a rolling mill as an example. In this F3 frame, there are 4 roll bending cylinders, and the rodless cavity area of ​​the roll bending cylinder is 283.385 cm 2 , the rod cavity area is 106.76cm 2 , the rack cooling water pressure is 12kg / cm 2 The back pressure of the bending roll back pressure system is 20kg / cm 2 The bending roller force setting reference value is 22000kg, and the rodless cavity pressure is 20kg / cm 2 .

[0061] Based on the above determined parameter information and the above defined calculation formula, the rodless cavity bending roll force is calculated as W p =22670.8kg, when the back pressure is not considered, the actual bending roll force is equal to the rodless cavity bending roll force W p , that is, the actual bending roll force is 22670.8kg. Then, based on the actual bending roll force obtained, strip rolling is carried out, and many plate shape abnormalities occur. When the back pressure is taken into account, the back pressure compensation bending roll force is W r =20*106.76*4=8540.8kg, actual bending roll force W after back pressure compensation a =W p -W r =22670.8-8540.8=14130kg, and then, the strip is rolled based on the actual bending roll force obtained, and basically no abnormal plate shape problem occurs.

[0062] The bending roll force control method of the hot rolling finishing bending roll back pressure system provided by one embodiment of the present invention can take into account the influence of the back pressure after increasing the bending roll back pressure system, avoid abnormal strip shape problems such as strip head crushing and tail swinging due to unstable bending roll force control during strip rolling, reduce abnormal downtime, and improve the plate shape control stability and plate shape quality during strip rolling.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this document are all referenced to the placement states shown in the accompanying drawings.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for controlling the bending force of a hot rolling finishing rolling bending roll back pressure system, characterized in that: The method is used for a hot rolling finishing mill equipped with a bending roll back pressure system, comprising: Determine the reference value for the bending roll force according to the type of steel strip being rolled; Determine the number of roll bending cylinders put into use, the cross-sectional area of ​​the rodless cavity, the cross-sectional area of ​​the rodded cavity and the pressure of the rodless cavity, as well as the back pressure put into use by the roll bending back pressure system at the current finishing mill stand; Calculate the rodless cavity bending force and back pressure compensation bending force according to the bending cylinder parameter information and back pressure; According to the rodless cavity bending roll force and the back pressure compensation bending roll force, the actual bending roll force after back pressure compensation is calculated, and the bending roll force is controlled based on the determined actual bending roll force after back pressure compensation and the bending roll force setting reference value; The rodless cavity bending roll force is calculated using the following formula: ； in, Indicates the rodless cavity bending roller force, Indicates the rodless chamber pressure of the bending roller cylinder, Indicates the cross-sectional area of ​​the rodless cavity of the bending roller cylinder, Indicates the number of roll bending cylinders put into use; The back pressure compensation bending force is calculated using the following formula: ； in, Indicates that the back pressure compensates the bending roll force, Indicates back pressure, Indicates the cross-sectional area of ​​the rod cavity of the bending roller cylinder, Indicates the number of roll bending cylinders put into use; The actual bending roll force after back pressure compensation is calculated using the following formula: ； in, Indicates the actual bending roll force after back pressure compensation; The roll bending force is controlled based on the actual roll bending force after back pressure compensation and the roll bending force setting reference value, including: According to the actual bending force after back pressure compensation and the bending force reference value, the given output of the bending servo valve is calculated and controlled in real time to control the bending force of the bending cylinder; The given output of the bending roll servo valve is calculated using the following formula: ； in, Indicates the given output of the bending roll servo valve at the nth sampling moment, Indicates the given output of the bending roll servo valve at the n-1th sampling moment, represents the proportionality coefficient, Indicates the scan time, represents the integration time, Indicates the bending roll force difference at the nth sampling moment, Indicates the bending roll force difference at the n-1th sampling moment, , Indicates the reference value of the bending roll force at the nth sampling moment, Indicates the actual bending roll force after back pressure compensation at the nth sampling moment.

2. The method for controlling the bending force of the hot rolling finishing rolling bending roll back pressure system according to claim 1, characterized in that: The method is used for controlling the bending roll force at the stands F1 to F7 of the hot rolling finishing mill group.

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