Method for Controlling the Snaking of a Rolled Material

Abstract

To reduce a meandering amount at a tail end part of a rolled material, and suppress occurrence of drawing.SOLUTION: A meandering control method for controlling meandering a rolled material: previously sets a threshold ETH of a first kind of parallel rigidity in which a meandering amount of a rolled material is less than an allowable value using at least any one of roll speed, a lubricant supply amount, a roll cross angle, a roll shift amount and a roll crown as a control parameter; calculates a first kind of parallel rigidity actual calculation value Eb; does not perform meandering control when the first kind of parallel rigidity actual calculation value Eb is less than the threshold ETH; calculates a change amount of the control parameter so that the first kind of parallel rigidity is set at the threshold ETH or less on the basis of the first kind of parallel rigidity actual calculation value Eb when the first kind of parallel rigidity actual calculation value Eb is larger than the threshold ETH; and controls the control parameter corresponding to the change amount on the basis of the calculated change amount of the control parameter while a tail end part of the rolled material passes through the rolling stand.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for controlling the meandering of the tail end portion of a material to be rolled.

Background Art

[0002] For example, when rolling a material to be rolled such as steel with a rolling stand, the center in the width direction of the material to be rolled may deviate from the mill center (the center position in the width direction of the rolling mill, that is, the center position in the rotation axis direction of the work roll), and the material to be rolled may move in the direction of the end portion of the work roll, resulting in a phenomenon called meandering. When meandering occurs, the flatness of the material to be rolled may deteriorate, which may lead to a decrease in product quality. In addition, when the amount of meandering is large, the tail end portion of the material to be rolled may come into contact with the side guide and bend, and a defect called choking may occur, in which the material to be rolled is bitten into the rolling mill in a state of being double-folded. When choking occurs, the surface of the work roll may be damaged by the bent rolled material, so it is necessary to stop the production line and perform maintenance work such as inspection, cleaning, or replacement of the work roll, which may reduce the operating rate of the production line.

[0003] Control methods for suppressing the meandering of the material to be rolled have been studied conventionally. For example, in Patent Document 1, a load cell of an arbitrary rolling stand (N-1) excluding the final finishing rolling stand among continuous finishing rolling mills of a strip or a rolled material detector provided in front of the rolling stand is used to detect the breakage of the rolled material at the previous rolling stand, and the roll gap of the next control target rolling stand N adjacent to the previous rolling stand is widened to thicken the tail portion of the material to be rolled, thereby preventing tail end choking. In addition, Patent Document 2 discloses a method for preventing the material to be rolled from being pinched due to interference with the side guide by narrowing the end portion in the body length direction of the work roll with a roll bending device when the rear end portion of the rolled material passes through, thereby suppressing the movement of the rolled material in the plate end direction.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 55-161505 [Patent Document 2] Japanese Patent Application Laid-Open No. 58-145303 [Non-Patent Document]

[0005] [Non-Patent Document 1] Hiroe Nakajima et al., "Research on the Snakelike Control Method in Hot Strip Rolling (First Report)", Spring Plastic Working Conference in 1980, pp. 61-64 [Non-Patent Document 2] Japan Iron and Steel Federation, "Theory and Practice of Plate Rolling (Revised Edition)", 2010, pp. 89-95 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in the method of controlling the snaking by opening the roll gap or applying a bending force when the trailing end of the material to be rolled passes through the rolling mill, as in the techniques described in Patent Documents 1 and 2 above, there is a risk that if the operation amount is too small and it leads to choking, or if the operation amount is too large and the trailing end of the material to be rolled is not rolled to the desired plate thickness or shape, the production yield may be reduced.

[0007] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for controlling the snaking of a material to be rolled that can reduce the amount of snaking at the trailing end of the material to be rolled, suppress the occurrence of choking, and reduce the yield loss caused by thickness defects and shape defects at the trailing end of the material to be rolled. [Means for Solving the Problems]

[0008] In order to solve the above problems, according to a certain aspect of the present invention, in the rolling of a material to be rolled by N rolling stands (N is a natural number), a method for controlling the meandering of the material to be rolled in the M-th stand (1 ≤ M ≤ N), which uses at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C as control parameters, and preliminarily sets a threshold value E of the first type of parallel rigidity at which the meandering amount of the material to be rolled in the M-th stand is less than the allowable value. TH A threshold value setting step of setting the threshold value, and a first type of parallel rigidity calculation step of calculating the actual calculation value E of the first type of parallel rigidity at the M-th stand. b If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. b If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. TH If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. b If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. TH If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. b If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided. TH If the actual calculation value E of the first type of parallel rigidity is less than or equal to the threshold value E, no meandering control is performed. If the actual calculation value E of the first type of parallel rigidity is greater than the threshold value E, a control step is included: calculating the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity less than or equal to the threshold value E based on the actual calculation value E of the first type of parallel rigidity, and controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand. A method for controlling the meandering of the material to be rolled is provided.

[0009] At least one of the rolling reduction position or the bending force may be further used as a control parameter.

[0010] In the first type of parallel rigidity calculation step, the actual rolling load value P and the actual bending force value F at the M-th stand, which are simultaneously obtained from when the tip of the material to be rolled bites into the M-th stand until before the tail end of the material to be rolled is rolled at the M-th stand, and based on the actual values of the control parameters, the actual calculation value E of the first type of parallel rigidity at the M-th stand may be calculated. b And the actual bending force value F b And based on the actual values of the control parameters, the actual calculation value E of the first type of parallel rigidity at the M-th stand may be calculated. b And based on the actual values of the control parameters, the actual calculation value E of the first type of parallel rigidity at the M-th stand may be calculated.

[0011] Alternatively, in the first type of parallel rigidity calculation step, the rolling load setting value P t and the bending force setting value F t at the Mth stand, and the setting values of the control parameters are calculated, and the first type of parallel rigidity setting calculation value E t at the Mth stand, the influence coefficient ∂E / ∂P of the rolling load, the influence coefficient ∂E / ∂F of the bending force, and the influence coefficient of the control parameter are calculated, and the rolling load actual value P b and the bending force actual value F b at the Mth stand, which are simultaneously obtained from when the tip of the material to be rolled bites into the Mth stand until before the tail end of the material to be rolled is rolled at the Mth stand, and the actual value of the control parameter are used to calculate the difference values between the setting value and the actual value respectively. Based on the difference values and the influence coefficients, the first type of parallel rigidity actual calculation value E b at the Mth stand may be calculated.

Advantages of the Invention

[0012] As described above, according to the present invention, it is possible to reduce the amount of meandering at the tail end of the material to be rolled, suppress the occurrence of drawing, and reduce the yield loss caused by thickness defects and shape defects at the tail end of the material to be rolled.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 11A

Figure 11B

Figure 12

Figure 13

Best Mode for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0015] [1. Configuration of Rolling Stand] First, based on FIG. 1, the schematic configuration of the rolling stand 10 according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing an example of the configuration of the rolling stand 10 according to the present embodiment. In FIG. 1, the state of the rolling stand 10 is shown as viewed from the working side in the roll barrel length direction, and it is assumed that the passing direction (rolling direction) of the material to be rolled S is from right to left in the drawing.

[0016] In addition, in FIG. 1, only one rolling stand 10 is illustrated, but such a rolling stand 10 can be, for example, one rolling mill that constitutes a finishing tandem rolling mill in hot rolling. The finishing tandem rolling mill is configured by arranging a plurality of rolling stands 10 in one direction. The material to be rolled is gradually thinned while continuously passing through each rolling stand, and finally has a desired plate thickness. Note that the present technology is also applicable to a single-stand rolling mill equipped with one rolling stand 10.

[0017] As shown in FIG. 1, the rolling stand 10 according to the present embodiment has a four-high rolling mill having a pair of work rolls 1 and 2 and a pair of reinforcing rolls 3 and 4 that support them. The upper work roll 1 is supported by the upper work roll chuck 5, and the lower work roll 2 is supported by the lower work roll chuck 6. The upper work roll chuck 5 and the lower work roll chuck 6 are similarly provided on the back side (drive side) of the drawing of FIG. 1, and support the upper work roll 1 and the lower work roll 2, respectively. The upper reinforcing roll 3 is supported by the upper reinforcing roll chuck 7, and the lower reinforcing roll 4 is supported by the lower reinforcing roll chuck 8. The upper reinforcing roll chuck 7 and the lower reinforcing roll chuck 8 are similarly provided on the back side (drive side) of the drawing of FIG. 1, and support the upper reinforcing roll 3 and the lower reinforcing roll 4, respectively. The upper work roll chuck 5, the lower work roll chuck 6, the upper reinforcing roll chuck 7, and the lower reinforcing roll chuck 8 are held by the housing 9.

[0018] The housing 9 has an inlet-side projection block 9a and an outlet-side projection block 9b that project inward from the housing 9 where the roll chocks 5 to 8 are arranged. The inlet-side projection block 9a and the outlet-side projection block 9b support the working roll chocks 5 and 6 via the increase bending devices 11a to 11d. Also, decrease bending devices 12a to 12d may be provided between the working roll chocks 5 and 6 and the reinforcing roll chocks 7 and 8.

[0019] The increase bending devices 11a to 11d are devices that apply a force in the direction of increasing the roll opening to the working roll chocks 5 and 6. The increase bending devices 11a to 11d are constituted by a driving device such as a hydraulic cylinder, for example. The decrease bending devices 12a to 12d are devices that apply a force in the direction of decreasing the roll opening to the working roll chocks 5 and 6. The decrease bending devices 12a to 12d are constituted by a driving device such as a hydraulic cylinder, for example.

[0020] The rolling reduction device 13 is installed above the upper reinforcing roll 3 which is the uppermost roll, and adjusts the positions in the rolling reduction direction of the upper reinforcing roll 3 and the upper working roll 1 (hereinafter, also referred to as "rolling reduction positions") to adjust the gap between the upper working roll 1 and the lower working roll 2. The rolling reduction device 13 is constituted by a driving device such as a hydraulic cylinder, for example. A rolling load detection device 14 for detecting a load in the rolling reduction direction (that is, the rolling load) is provided between the rolling reduction device 13 and the upper reinforcing roll chock 7. The rolling load detection device 14 may be a load cell, for example.

[0021] The working rolls 1 and 2 rotate at a predetermined roll speed and reduce the thickness of the material to be rolled S with a predetermined pressure from above and below, thereby making the material to be rolled S have a predetermined thickness while passing it in one direction. The reduction positions of the working rolls 1 and 2 (i.e., the roll gap) are appropriately adjusted by the reduction device 13 according to rolling conditions such as the target value of the thickness of the material to be rolled S after rolling and the reduction ratio. The roll speeds of the working rolls 1 and 2 can be changed by a driving device (not shown) such as a motor. Also, a lubricant supply device (not shown) for supplying a lubricant to the material to be rolled S during rolling may be installed on the inlet side of the rolling stand 10.

[0022] Note that the rolling stand 10 may be able to change the roll crossing angle by moving the roll chocks 5 to 8, for example, like a pair cross rolling mill. Alternatively, the rolling stand 10 may be able to shift the working rolls 1 and 2, or the intermediate roll, in the axial direction, for example, like a CVC (continuous variable crown) rolling mill or a six-high rolling mill. Furthermore, the rolling stand 10 may be able to change the roll crown of the working rolls 1 and 2, for example, like a VC (variable crown) rolling mill. The roll crown can be changed, for example, by using variable crown rolls having hydraulic chambers for expansion inside the center of the barrel length of the rolls as the working rolls 1 and 2.

[0023] In the rolling stand 10, when the trailing end of the material to be rolled S passes through the rolling stand 10, snake control is performed by the snake control device 100. The snake control device 100 changes at least one of the control parameters, including the roll speed, lubricant supply amount, roll crossing angle, roll shift amount, and roll crown, according to the first type of parallel rigidity, which is an index of the ease of snake movement at the trailing end of the material to be rolled S. Note that the roll shift amount includes not only the work roll shift amount but also the intermediate roll shift amount when there is an intermediate roll as in a six-high rolling mill. In addition to these control parameters, the snake control device 100 may further drive the increase bending devices 11a to 11d or the roll gap control device 13 to apply a bending force or change the roll gap position by a required amount. Thereby, the amount of snake movement at the trailing end of the material to be rolled S is reduced, and the occurrence of necking is suppressed. Note that the bending force may be applied by driving not only the increase bending devices 11a to 11d but also the decrease bending devices 12a to 12d.

[0024] The snake control device 100 is constituted by various processors such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), for example, and the functions of the snake control device 100 can be realized by the processor operating according to a predetermined program.

[0025] Also, whether or not to perform snake control by the snake control device 100 is determined based on the calculated value of the first type of parallel rigidity actual performance as described above. The calculation of the calculated value of the first type of parallel rigidity actual performance is performed by an arithmetic processing unit (the arithmetic processing unit 200 in FIG. 4 or FIG. 12 described later). The arithmetic processing unit is also constituted by various processors such as a CPU or a DSP, for example. The functions of the arithmetic processing unit can be realized by the processor operating according to a predetermined program.

[0026] Note that the meandering control device 100 only needs to have a function of controlling the operation of the rolling stand 10, and its specific configuration is not limited. Similarly, the arithmetic processing device only needs to have a function of calculating the first type of parallel rigidity achievement value, and its specific configuration is not limited. For example, the meandering control device 100 and the arithmetic processing device may be various processors as described above, or may be a so-called microcomputer in which a processor and a storage device such as a memory are integrally configured. Alternatively, the meandering control device 100 and the arithmetic processing device may be various information processing devices such as a PC (Personal Computer) or a server.

[0027] [2. Meandering control of the trailing end] The meandering control of the trailing end of the material to be rolled by the meandering control device 100 according to the present embodiment calculates the first type of parallel rigidity achievement value, and according to the calculated first type of parallel rigidity achievement value, if necessary, the roll speed, the lubricant supply amount, the roll crossing angle, the roll shift amount, and the roll crown are changed by at least any one of the control parameters by a necessary amount.

[0028] The first type of parallel rigidity changes according to changes in the rolling load and bending force from the tip to the tail of the material to be rolled. The first type of parallel rigidity at the tip of the material to be rolled corresponds to the first type of parallel rigidity obtained by the setting calculation before rolling, and has a relatively weak correlation with the meandering of the trailing end of the material to be rolled. In contrast, the first type of parallel rigidity immediately before the trailing end of the material to be rolled shown in FIG. 2 (measurement timing 2 in FIG. 10) has a relatively high correlation with the meandering of the trailing end of the material to be rolled compared to the tip. Therefore, in the present embodiment, preferably, the first type of parallel rigidity immediately before the trailing end of the material to be rolled is calculated, and based on this, meandering control is performed to suppress the meandering of the trailing end of the material to be rolled.

[0029] Here, the meandering of the material to be rolled is caused by the plate thickness difference in the left-right (width direction) of the material to be rolled on the outlet side of the rolling stand (that is, the outlet wedge amount) h df The outlet wedge amount h df is represented by the following formula (1) (see, for example, Non-Patent Document 1).

[0030]

Number

[0031] In the above formula (1), S df is the left - right roll opening difference, P df is the left - right rolling load difference, a is the distance between roll fulcrums, and b is the plate width. Also, E is the first - type parallel rigidity and D is the second - type parallel rigidity, and these are the basic constants of the rolling mill related to the snake - like phenomenon.

[0032] The equation for the amount of snake - like movement of the material to be rolled ultimately reduces to the differential equation of the following formula (2) (see, for example, Non - Patent Document 1).

[0033]

Number

[0034] Here, v1 is the speed on the incoming side of the rolled material, y c is the amount of snake - like movement, ξ is the advance constant, h is the outgoing - side plate thickness, m is the plastic coefficient, and Perturbation is a left - right asymmetric disturbance term (for example, influence terms such as incoming - side wedges, left - right deformation resistance differences, leveling, etc.).

[0035] Here, let the coefficients of each term in the above formula (2) be M and k as follows.

[0036]

Number

[0037] Regarding M as the mass and k as the spring constant, it can be seen that the above formula (2) has the same form as the equation of motion of a mass - spring system. Since k, which is the spring constant, mostly takes negative values, snake - like movement is essentially an unstable phenomenon (a divergent system). To suppress snake - like movement, there are roughly three approaches as follows.

[0038] (a) Reduce various left - right asymmetric disturbances (that is, minimize Perturbation) (b) Cancel other disturbances using operable left-right asymmetric disturbances (leveling). (That is, minimize the Perturbation.) (c) Minimize the divergence rate of the snake-like movement when a disturbance occurs. (That is, minimize the absolute value of k.)

[0039] The snake-like movement control method according to this embodiment is based on the approach of (c) above. However, it is also possible to use it in combination with the approaches of (a) and (b). Further, when evaluating the degree of snake-like movement, physically, it is reasonable to include not only the first type of parallel rigidity E but also the second type of parallel rigidity D according to the above formula (1). However, the second type of parallel rigidity D does not change significantly during rolling compared to the first type of parallel rigidity E that varies during rolling due to the rolling load and bending force. In other words, the second type of parallel rigidity D cannot be changed. Therefore, in the snake-like movement control method according to this embodiment, for practical simplicity, the degree of snake-like movement is evaluated based only on the first type of parallel rigidity E.

[0040] Specifically, in the rolling of the material to be rolled by N (N is a natural number) rolling stands, when controlling the snake-like movement of the material to be rolled at the M-th stand (1 ≤ M ≤ N), using the control parameters for controlling the snake-like movement of the material to be rolled, in advance, the threshold value E of the first type of parallel rigidity at the M-th stand where the snake-like movement amount of the material to be rolled is less than the allowable value TH is set (threshold setting step). Also, before rolling, the actual calculated value Eb of the first type of parallel rigidity at the M-th stand is calculated (first type of parallel rigidity calculation step). Then, the threshold value E of the first type of parallel rigidity TH and the actual calculated value E of the first type of parallel rigidity b are compared.

[0041] If the actual calculated value E of the first type of parallel rigidity b is less than or equal to the threshold value E TH , no snake-like movement control is performed. On the other hand, if the actual calculated value E of the first type of parallel rigidity b is greater than the threshold value E TH , based on the actual calculated value E of the first type of parallel rigidity b , the first type of parallel rigidity is set to the threshold value ETH Calculate the amount of change in the control parameter of the Mth stand for the following. Then, while the trailing end of the material to be rolled passes through the Mth stand, control the control parameter at the Mth stand based on the amount of change in the control parameter (control step).

[0042] Here, the calculated value E of the first type of parallel rigidity performance at the Mth stand b is calculated, for example, by calculating the influence coefficient with respect to the calculated value E of the first type of parallel rigidity setting of the material to be rolled calculated by the setup calculation, and using the influence coefficient to calculate the calculated value E of the first type of parallel rigidity performance t or a method of calculating the calculated value E of the first type of parallel rigidity performance based on the rolling conditions using a model is conceivable. Hereinafter, the meandering control of the trailing end of the material to be rolled according to the present embodiment will be described in detail. b b b In the present embodiment, the trailing end of the material to be rolled refers to a range from the trailing end to a predetermined length. Here, the predetermined length is a length at which the effect of reducing meandering can be exhibited when the meandering control method of the material to be rolled according to the present invention is applied to the set range as the trailing end of the material to be rolled. Since this length also varies depending on the specifications of the rolling mill, the dimensions of the material to be rolled, and the material of the material to be rolled, for example, the plate width of the material to be rolled may be set as the initial value of the predetermined length, and it may be obtained after adjustment in actual operation.

[0043]

[0044] In the case of the stands after the second stand of tandem rolling, the trailing end of the material to be rolled may be, for example, "the range from the trailing end to the position bitten at the Mth stand which is the control target when the trailing end of the material to be rolled passes through the rolling stand one upstream of the Mth stand which is the control target (that is, the (M - 1)th stand)". Alternatively, "the distance between the (M - 1)th stand and the Mth stand" may be used as the trailing end of the material to be rolled in the case of the stands after the second stand of tandem rolling.

[0045] [2-1. Example of meandering control 1 (Calculation of the calculated value of the first type of parallel rigidity performance using the calculated value of the first type of parallel rigidity setting and the influence coefficient in the setup calculation)] First, based on FIGS. 3 to 11B, as serpentine control example 1, the first type of parallel rigidity actual calculation value is calculated using the first type of parallel rigidity setting calculation value and the influence coefficient in the setup calculation, and the case of performing serpentine control on the tail end of the material to be rolled will be described. FIG. 3 is a flowchart showing the processing of serpentine control example 1. FIG. 4 is the first type of parallel rigidity actual calculation value E in serpentine control example 1 b is a schematic diagram showing an overview of the calculation process. FIG. 5 is the actual rolling load value P of the material to be rolled b and the actual bending force value F b from which the first type of parallel rigidity actual calculation value E b is calculated by linear approximation, is a schematic diagram showing the concept. FIG. 6 is an explanatory diagram for explaining the method of calculating the influence coefficient of the first type of parallel rigidity with respect to the rolling load. FIG. 7 is an explanatory diagram for explaining the method of calculating the influence coefficient of the first type of parallel rigidity with respect to the bending force. FIG. 8 is a graph showing an example of the correlation between the first type of parallel rigidity actual calculation value (using the model) and the first type of parallel rigidity actual calculation value (using the influence coefficient). FIG. 10 is an explanatory diagram showing the rolling stand that is the control target of the serpentine control method for the material to be rolled according to the present embodiment, and the measurement timing of the rolling load and the bending force at that time. FIGS. 11A and 11B are flowcharts showing modified examples of the processing of serpentine control example 1.

[0046] (S100: Selection of control parameters) In serpentine control example 1, as shown in FIG. 3, first, as control parameters, at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C is used (S100). The control parameters can be selected based on the purpose of emphasizing the reduction of the serpentine amount (prevention of the occurrence of squeezing) in the serpentine control at the tail end of the material to be rolled, and the restrictions on the equipment configuration of the rolling stand 10, etc. The purposes of emphasizing along with the reduction of the serpentine amount include, for example, the reduction of the yield loss due to the sheet thickness defect at the tail end of the material to be rolled, the reduction of the yield loss due to the shape defect, etc.

[0047] The selection of control parameters may be performed, for example, by an operator who inputs them into an arithmetic processing unit described later using an input device or the like. Alternatively, based on the equipment configuration of the rolling stand 10, the arithmetic processing unit may automatically select the control parameters. At this time, for each of the rolling stands 10, the priority of the purpose to be emphasized while reducing the amount of lateral movement may be determined in advance, and the combination of control parameters selected accordingly may be stored in the storage unit of the arithmetic processing unit. Thereby, if the operator inputs the priority of the purpose to be emphasized while reducing the amount of lateral movement into the arithmetic processing unit, the arithmetic processing unit can automatically select the control parameters.

[0048] For example, when the roll speed V or the lubricant supply amount Q is used as a control parameter, since it does not interfere with shape control, it is effective in reducing the yield loss due to shape defects. There is also an advantage that the control of the roll speed V or the lubricant supply amount Q can be carried out regardless of the type of the rolling stand. Further, when the roll cross angle θ, the roll shift amount L, or the roll crown C is used as a control parameter, although it interferes with shape control and yield loss due to shape defects is likely to occur, it is effective in reducing the yield loss due to sheet thickness defects. Also, when controlling the roll speed V or the lubricant supply amount Q, there are cases where it is difficult to obtain a sufficient effect of preventing the occurrence of drawing depending on the rolling conditions, but when controlling the roll cross angle θ, the roll shift amount L, or the roll crown C, there is an advantage that a stable effect of preventing the occurrence of drawing can be obtained. The roll cross angle θ, the roll shift amount L, and the roll crown C have limited controllable parameters depending on the type of the rolling stand.

[0049] When the priority changes depending on conditions, it is also possible to use a combination of multiple control parameters and adjust the balance of the control amounts of the control parameters according to the rolling conditions. Also, by using more control parameters, the controllable range is expanded (the effect of suppressing drawing increases). Therefore, for example, when it is desired to suppress the occurrence of drawing as much as possible on the premise of giving priority to reducing the yield loss due to shape defects, it is desirable to select both the roll speed V and the lubricant supply amount Q as control parameters. Also, for example, when it is desired to prevent the occurrence of drawing as much as possible on the premise of giving priority to reducing the yield loss due to sheet thickness defects, it is desirable to use all controllable control parameters among the roll cross angle θ, the roll shift amount L, and the roll crown C.

[0050] (S110: Threshold setting step) When the control parameters are selected in step S100, a threshold value E of the first type of parallel rigidity is set in advance before rolling so that the meandering amount of the material to be rolled is less than the allowable value. TH (S110). For example, based on past operating results, preferably, the correlation between the first type of parallel rigidity and the tail-end meandering amount as shown in FIG. 2 is obtained in advance, and the value of the first type of parallel rigidity at which the meandering amount is less than the allowable value is set as the threshold value E. TH That's all.

[0051] (S120~S130: First type of parallel rigidity calculation step) Next, the actual calculation value E of the first type of parallel rigidity is calculated. In the meandering control example 1, the actual calculation value E of the first type of parallel rigidity is calculated using the set calculation value Et of the first type of parallel rigidity and the influence coefficient. Explaining together with the outline of the first type of parallel rigidity calculation step shown in FIG. 4, first, setup calculation using a model is performed for the Mth stand to be controlled, and the set calculation value E of the first type of parallel rigidity b and the influence coefficient are calculated (S120). Such calculations are performed immediately before rolling. b and the influence coefficient are calculated (S120). Such calculations are performed immediately before rolling. t and the influence coefficient are calculated (S120). Such calculations are performed immediately before rolling.

[0052] The set calculation value E of the first type of parallel rigidity tAs a model for calculating the influence coefficients, for example, the Mills stretch model can be used (see, for example, Non-Patent Document 2). The arithmetic processing unit 200 receives, as rolling conditions, the rolling load set value P of the material to be rolled obtained by the setup calculation t and the bending force set value F t and the roll cross angle set value θ t , the roll shift amount set value L t , and the roll crown set value C t Among them, the set value of the control parameter selected in step S100 and various other rolling conditions are input. The roll speed set value V b and the lubricant supply amount set value Q b affect the first type of parallel rigidity through the rolling load, so they are omitted from the input values because their influence is included in the rolling load set value P t . Here, the rolling load and bending force with the rolling load set value P t and the bending force set value F t are parameters that have large online fluctuations and affect the first type of parallel rigidity.

[0053] Then, the arithmetic processing unit 200 performs a setup calculation using the Mills stretch model, and calculates the first type of parallel rigidity set calculation value E t and the influence coefficients ∂E / ∂P of the rolling load P and ∂E / ∂F of the bending force F with respect to the first type of parallel rigidity set calculation value E t . Further, the arithmetic processing unit 200 calculates at least one of the influence coefficients of the control parameter selected in step S100, that is, the influence coefficient ∂E / ∂V of the roll speed V, the influence coefficient ∂E / ∂Q of the lubricant supply amount Q, the influence coefficient ∂E / ∂θ of the roll cross angle θ, the influence coefficient ∂E / ∂L of the roll shift amount L, and the influence coefficient ∂E / ∂C of the roll crown C with respect to the first type of parallel rigidity set calculation value E t . Each influence coefficient is represented by the following formulas (4-1) to (4-7).

[0054]

Equation

[0055] Note that the calculation in step S120 may be performed using a model other than the mill stretch model.

[0056] When the first type of parallel rigidity setting calculation value E t and the influence coefficient are calculated, next, based on the actual rolling load value P b of the material to be rolled and the actual bending force value F b and the actual roll crossing angle value θ b the actual roll shift amount value L b and the actual roll crown value C b among them, based on the actual values of the control parameters selected in step S100, the first type of parallel rigidity actual calculation value E b is calculated (S130). In the first-order approximation formula (5), X is the actual roll crossing angle value θ b the actual roll shift amount value L b and the actual roll crown value C b among them, representing the control parameters selected in step S100. Here, the actual roll speed value V b and the actual lubricant supply amount value Q b are omitted from X because they affect the first type of parallel rigidity through the rolling load.

[0057] The actual rolling load value P b and the actual bending force value F b may use measured values. The actual rolling load value P b and the actual bending force value F b are simultaneously acquired between when the tip of the material to be rolled bites into the Mth stand and before the tail end of the material to be rolled is rolled at the Mth stand. The actual roll crossing angle value θ b the actual roll shift amount value L b and the actual roll crown value C b may use the currently set values. For example, at the start of control, the initial set values are used, and when the values are changed in step S150 described later, the changed values are used.

[0058]

Number

[0059] In the multi-dimensional surface representing the relationship between the first type of parallel rigidity E, the rolling load P, the bending force F, and the selected control parameter, the first type of parallel rigidity set calculation value E t from the first type of parallel rigidity actual calculation value E b to the change can be regarded as being represented by a first-order approximation. For example, for the sake of simplicity of explanation, considering the surface C shown in FIG. 5 that represents the relationship between the first type of parallel rigidity E, the rolling load P, and the bending force F, in the surface C, the first-order approximation formula (5) is the first type of parallel rigidity set calculation value E t (point A) to the first type of parallel rigidity actual calculation value E b (point B) can be regarded as being represented by a first-order approximation. This can be said for the following reasons.

[0060] First, the relationship between the first type of parallel rigidity E and the rolling load P is shown, for example, as in FIG. 6. At this time, considering that the rolling load set value P t of the material to be rolled increases by an arbitrary value h p , by dividing the increase amount of the first type of parallel rigidity E at that time by h p , the influence coefficient ∂E / ∂P of the rolling load P on the first type of parallel rigidity E in the first-order approximation can be expressed by the following formula (6). If the linearity of the correlation between the first type of parallel rigidity E and the rolling load P is strong, such a first-order approximation is sufficient, but if the non-linearity is strong, the influence coefficient may be obtained more precisely by a second-order approximation or the like.

[0061]

Number

[0062] Also, the relationship between the first type of parallel rigidity E and the bending force F is shown, for example, as in FIG. 7. At this time, the bending force set value F t of the material to be rolled is an arbitrary value h FIf we consider that only the value has increased, the increase amount h of the first type of parallel rigidity E at that time is F Dividing by this, the influence coefficient ∂E / ∂F of the bending force F on the first type of parallel rigidity E in the first-order approximation can be expressed by the following formula (7). Let this be the influence coefficient ∂E / ∂F. If the linearity of the correlation between the first type of parallel rigidity E and the bending force F is strong, such a first-order approximation is sufficient, but if the non-linearity is strong, the influence coefficient can be obtained by second-order approximation or the like.

[0063]

Number

[0064] The same applies to the control parameters X of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C. The relationship between the first type of parallel rigidity E and each control parameter X can be expressed as shown in FIG. 8. The set value X of the control parameter t If it is considered that has increased by an arbitrary value h X If we consider that only the value has increased, the increase amount h of the first type of parallel rigidity E at that time is X Dividing by this, the influence coefficient ∂E / ∂X of the control parameter X on the first type of parallel rigidity E in the first-order approximation can be expressed by the following formula (8). Let this be the influence coefficient ∂E / ∂X. If the linearity of the correlation between the first type of parallel rigidity E and each control parameter X is strong, such a first-order approximation is sufficient, but if the non-linearity is strong, the influence coefficient can be obtained by second-order approximation or the like.

[0065]

Number

[0066] That is, the influence coefficient ∂E / ∂P of the rolling load P on the first type of parallel rigidity E represented by the above formula (6), the influence coefficient ∂E / ∂F of the bending force F on the first type of parallel rigidity E represented by the above formula (7), and the influence coefficient ∂E / ∂X of the control parameter X on the first type of parallel rigidity E represented by the above formula (8) represent the influence on the first type of parallel rigidity E due to changes in the rolling load P, the bending force F, and the control parameter X. By using these, the actual calculation value E of the first type of parallel rigidity b can be expressed by the above first-order approximation formula (5).

[0067] Fig. 9 shows an example of the correlation between the actual calculation value of the first type of parallel rigidity (using the model) calculated using the mill stretch model based on the actual values of the rolling conditions and the actual calculation value of the first type of parallel rigidity (using the influence coefficient) calculated using the above first-order approximation formula (5). Here, as shown in (measurement timing 2) of Fig. 10, the actual value of the rolling conditions uses the value measured immediately before the tail end S of the material to be rolled S b is rolled at the stand. As shown in Fig. 9, the correlation coefficient between the actual calculation value of the first type of parallel rigidity (using the model) and the actual calculation value of the first type of parallel rigidity (using the influence coefficient) is approximately 1.00, and the actual calculation value of the first type of parallel rigidity (using the model) and the actual calculation value of the first type of parallel rigidity (using the influence coefficient) are in agreement. From this, as in the snake control example 1, by using the first-order approximation influence coefficients for the rolling load P, the bending force F, and the control parameter X, the actual calculation value E of the first type of parallel rigidity b It can be seen that the first type of parallel rigidity can be calculated with the same accuracy as the exact solution calculated by model calculation by calculating

[0068] Thus, in the snake control example 1, the model calculation, which is a high-load calculation, is performed in advance before rolling to obtain the set calculation value E of the first type of parallel rigidity representing the influence on snake, t the influence coefficient ∂E / ∂P of the rolling load P on the set calculation value E of the first type of parallel rigidity, the influence coefficient ∂E / ∂F of the bending force F, and the influence coefficient ∂E / ∂X of the control parameter selected in step S100 are obtained, and from the actual changes in the rolling load P and the bending force F during rolling, the actual calculation value E of the first type of parallel rigidity is obtained by simple calculation t b ​Seek to obtain this. As a result, the calculation load during rolling can be reduced, and application to an actual machine can be easily realized.

[0069] Here, the actual rolling load value P in step S130 b and the actual bending force value F b , and the acquisition of the actual values of other control parameters is, as described above, simultaneously acquired during the period from when the tip of the material to be rolled bites into the Mth stand to be controlled until the trailing end of the material to be rolled is rolled at the Mth stand. Specifically, the actual rolling load value P b and the actual bending force value F b are measured at the timings shown in FIG. 10.

[0070] First, when it is a tandem rolling mill having N (N≥2) rolling stands, when the Mth stand is any one of the 2nd stand to the Nth stand, as shown in the upper part of FIG. 10, the actual rolling load value P b and the actual bending force value F b are measured from the timing (measurement timing 1) when the tip T of the material to be rolled A bites into the Mth stand (#M) until before the trailing end S b of the material to be rolled S is rolled at the Mth stand (#M) (measurement timing 2). The trailing end S b is, as described above, in the range from the trailing end T to a predetermined length. Also, when the 1st stand (#1) of the tandem rolling mill is the control target, as shown in the center of FIG. 10, the actual rolling load value P b and the actual bending force value F b are measured from the timing (measurement timing 1) when the tip T of the material to be rolled A bites into the 1st stand (#1) until before the trailing end S b of the material to be rolled S is rolled at the 1st stand (#1) (measurement timing 2).

[0071] Also, in the case of a single-stand rolling mill, as shown in the lower part of FIG. 10, the actual rolling load value P b and the actual bending force value F bis measured from the timing when the tip T of the material to be rolled A engages with the first stand (#1) (measurement timing 1) until before the trailing end S of the material to be rolled S b is rolled at the first stand (#1) (measurement timing 2).

[0072] Note that the actual rolling load value P b and the actual bending force value F b are preferably measured when the part close to the trailing end S b is rolled by the M-th stand which is the control target as much as possible when there is a margin in the calculation time.

[0073] (S140~S160: Control steps) When the first type of parallel rigidity actual calculation value E b is calculated in step S130, the snake control device 100 determines whether to perform snake control on the trailing end of the material to be rolled at the M-th stand by comparing the first type of parallel rigidity actual calculation value E b with the threshold value E TH (S140).

[0074] When the first type of parallel rigidity actual calculation value E b is less than or equal to the threshold value E TH (that is, in the case of E b ≦E TH ), since the degree of snake of the trailing end of the material to be rolled is small, snake control is not performed, and the process proceeds to the process of step S170 described later.

[0075] On the other hand, when the first type of parallel rigidity actual calculation value E b is greater than the threshold value E TH (that is, in the case of E b >E TH ), since the degree of snake of the trailing end of the material to be rolled is large, snake control is performed. Therefore, first, the snake control device 100 calculates the change amount ΔX of the control parameter selected in step S100 at the M-th stand to make the first type of parallel rigidity actual calculation value E b less than or equal to the threshold value E TH (S150).

[0076] Specifically, the meandering control device 100 calculates its control amount (change amount) according to the control parameters of the meandering control. How to perform the meandering control may be arbitrarily set within the range that satisfies the constraints on facilities and the constraints on shape control.

[0077] When performing meandering control by changing the roll speeds of the working rolls 1 and 2 with a driving device such as a motor, a roll speed change amount ΔV that satisfies the following formula (9) is calculated.

[0078]

Equation

[0079] When performing meandering control by changing only the lubricant supply amount Q with a lubricant supply device, a lubricant supply amount change amount ΔQ that satisfies the following formula (9) is calculated.

[0080]

Equation

[0081] When performing meandering control by moving the roll chock and changing only the roll cross angle θ, a roll cross angle change amount Δθ that satisfies the following formula (11) is calculated.

[0082]

Equation

[0083] When performing meandering control by shifting the working roll in the axial direction and changing only the roll shift amount L, a roll shift amount change amount ΔL that satisfies the following formula (12) is calculated.

[0084]

Equation

[0085] When performing snaking control by changing only the roll crown C of the work roll, a roll crown change amount ΔC that satisfies the following formula (13) is calculated.

[0086]

Number

[0087] When multiple control parameters are selected from the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C as control parameters, as shown in the following formula (14), the sum of the products of the change amount ΔX of the selected control parameter X and the influence coefficient ∂E / ∂X is the first-kind parallel rigidity actual calculation value E b and the threshold value E TH The change amount ΔX of each control parameter X is calculated as a control amount so that it is less than or equal to the difference from.

[0088]

Number

[0089] When the change amount is calculated in step S150, the snaking control device 100 controls the control parameter X based on the calculated change amount ΔX of the control parameter X (S160). Thereby, snaking control of the tail end portion of the material to be rolled at the Mth stand is performed.

[0090] (S170: Confirmation of change in control amount) Thereafter, it is confirmed whether there is a change in the control amount (change amount) in the snaking control of the tail end portion (S170). For example, when the temperature of the steel plate fluctuates while rolling the tail end portion of the material to be rolled at the Mth stand which is the control target, the rolling load changes and the value of the first-kind parallel rigidity actual calculation value also changes. In such a case, it is desirable to recalculate the first-kind parallel rigidity actual calculation value E b and correct the control amount.

[0091] Therefore, in step S170, the snake control device 100 checks whether there is a change in the control amount. If there is no change in the control amount, the process of FIG. 3 is terminated as it is. On the other hand, if there is a change in the control amount, the snake control device 100 instructs the arithmetic processing device 200 to execute the process from step S130 again. The process from step S130 again may be executed at any time, for example, at any timing between when the tip of the material to be rolled bites into the Mth stand to be controlled and before the tail end of the material to be rolled is rolled at the Mth stand.

[0092] For example, first, when the tail end of the material to be rolled exits the first stand, the processes of steps S130 to S160 are performed. Next, when it exits the second stand, the processes of steps S130 to S160 are performed. Further, when it exits the third stand, the processes of steps S130 to S160 are performed. In this way, the necessity of snake control at the Mth stand is confirmed multiple times between when the tip of the material to be rolled bites into the Mth stand to be controlled and before the tail end of the material to be rolled is rolled at the Mth stand. When the degree of snake is large, snake control is performed. Thereby, the occurrence of snake can be more reliably suppressed.

[0093] (Modification example) In the snake control example 1 shown in FIG. 3, in step S100, at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C was selected as a control parameter. However, further, at least one of the reduction position S or the bending force F may be selected as a control parameter. Hereinafter, based on FIGS. 11A and 11B, the process when at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C and at least one of the reduction position S or the bending force F are selected as control parameters will be described. Note that in the following description, detailed descriptions of processes similar to those in FIG. 3 will be omitted.

[0094] (S200: Selection of control parameters) As shown in Fig. 11A, first, as control parameters, at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C, and at least one of the reduction position S or the bending force F are used (S200). As described above, the control parameters can be selected based on the purpose of emphasizing the reduction of the meandering amount in the meandering control at the trailing end of the material to be rolled, and the constraints in the equipment configuration of the rolling stand 10, etc. Also, the selection of the control parameters may be performed by the operator, or the arithmetic processing unit may automatically select the control parameters.

[0095] For example, when the reduction position S is used as a control parameter, since it does not interfere with shape control, it is effective in reducing the yield loss due to shape defects. Also, when the bending force F is used as a control parameter, since it interferes with shape control, yield loss due to shape defects is likely to occur, but it is effective in reducing the yield loss due to sheet thickness defects. The control of the reduction position S or the bending force F is generally equipped with a control device in most rolling stands and can be easily implemented.

[0096] By combining at least one of the reduction position S or the bending force F with at least one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C and using them as control parameters, meandering control that makes use of the characteristics of each control parameter becomes possible.

[0097] For example, when considering the case of using three control parameters, namely the roll speed V, the lubricant supply amount Q, and the reduction position S, all of these are control parameters that reduce the first type of parallel rigidity E by changing the rolling load P. Since the roll speed V, the lubricant supply amount Q, and the reduction position S do not affect the shape defect of the material to be rolled, compared with other parameters (roll cross angle θ, roll shift amount L, roll crown C, and bending force F), they have a higher effect of reducing the yield loss due to shape defects. Note that when a hydraulic reduction device is provided, the reduction position S can be controlled with high responsiveness, so it has a higher effect of preventing the occurrence of necking compared with the roll speed V or the lubricant supply amount Q. On the other hand, since the roll speed V and the lubricant supply amount Q reduce the first type of parallel rigidity E without significantly changing the reduction amount, they have a higher effect of reducing the yield loss due to sheet thickness defects compared with the reduction position S.

[0098] Also, for example, when considering the case of using four control parameters, namely the roll cross angle θ, the roll shift amount L, the roll crown C, and the bending force F, all of these are control parameters that reduce the first type of parallel rigidity E by increasing the sheet crown. Since the roll cross angle θ, the roll shift amount L, the roll crown C, and the bending force F do not affect the average sheet thickness of the material to be rolled, compared with other parameters (roll speed V, lubricant supply amount Q, reduction position S), they have a higher effect of reducing the yield loss due to sheet thickness defects.

[0099] Furthermore, when using other parameters (roll speed V, lubricant supply amount Q, reduction position S), the first type of parallel rigidity E may not change significantly even when the rolling load is changed. For example, when the influence of the elongation deformation of the rolling stand caused by the change in the rolling load P on the first type of parallel rigidity E and the influence of the deflection deformation of the rolling stand caused by the change in the rolling load P on the first type of parallel rigidity E cancel each other out, etc. In this case, although a sufficient effect of preventing the occurrence of necking cannot be obtained, as control parameters, the roll crossing angle θ, roll shift amount L, roll crown C, and bending force F are used, and if controlled so that the plate crown increases, it is possible to reduce the first type of parallel rigidity E even under most conditions including the above-mentioned cases. Therefore, the roll crossing angle θ, roll shift amount L, roll crown C, and bending force F have a greater effect of preventing the occurrence of necking than other parameters (roll speed V, lubricant supply amount Q, reduction position S).

[0100] Note that the bending force F is generally equipped with a control device in most rolling stands and is a controllable parameter that can be used regardless of the equipment configuration of the rolling stand, so it can be controlled more simply than the roll crossing angle θ, roll shift amount L, and roll crown C. On the other hand, the roll crossing angle θ, roll shift amount L, and roll crown C often have a relatively large controllable range, so the effect of preventing the occurrence of necking is slightly greater than that of the bending force F.

[0101] Based on the above, for example, the use of control parameters such as the following cases a to f can be considered. In the description of the priority of the purpose, the reduction in yield due to shape defects is described as "shape", the reduction in yield due to sheet thickness defects is described as "sheet thickness", and the prevention of the occurrence of necking is described as "necking". Also, for cases c, d, and f, the available control parameters may be selected according to the equipment configuration of the rolling stand.

[0102] (Case a: Shape > Sheet thickness > Necking) → Roll speed V, Lubricant supply amount Q (Case b: Shape > Necking > Sheet thickness) → Reduction position S (Case c: Sheet thickness > Shape > Necking) →Roll cross angle θ, roll shift amount L, roll crown C, bending force F (Case d: Plate thickness > drawing > shape) →Roll cross angle θ, roll shift amount L, roll crown C, bending force F (Case e: Drawing > shape > plate thickness) → Reduction position S (Case f: Drawing > plate thickness > shape) →Roll cross angle θ, roll shift amount L, roll crown C, bending force F

[0103] When the priority changes depending on conditions, for example, when there are Case a and Case b, at least one of the reduction position S and the roll speed V or the lubricant supply amount Q is used in combination, and it is also possible to adjust the balance of the control amounts of the control parameters according to the rolling conditions. Also, by using more control parameters, the controllable range is expanded (the effect of preventing drawing increases). Therefore, for example, when it is desired to suppress the occurrence of drawing as much as possible on the premise of prioritizing the reduction of yield loss due to shape defects, it is desirable to select all of the reduction position S, the roll speed V, and the lubricant supply amount Q as control parameters. Also, for example, when it is desired to prevent the occurrence of drawing as much as possible on the premise of prioritizing the reduction of yield loss due to plate thickness defects, it is desirable to use all controllable control parameters among the bending force F, the roll cross angle θ, the roll shift amount L, and the roll crown C.

[0104] (S210: Threshold setting step) When the control parameters are selected in step S200, a threshold value E of the first type of parallel rigidity is set in advance before rolling so that the meandering amount of the material to be rolled is less than the allowable value (S210). Step S210 may be implemented in the same manner as step S110 in FIG. 3. TH is set (S210). Step S210 may be implemented in the same manner as step S110 in FIG. 3.

[0105] (S220~S230: First type of parallel rigidity calculation step) Next, the actual calculation value E of the first type of parallel rigidity b is calculated. In the meandering control example 1, the actual calculation value E of the first type of parallel rigidity t is calculated using the set calculation value E of the first type of parallel rigidity and the influence coefficient.b Calculate it. Basically, step S220 in FIG. 11A may be implemented in the same manner as step S120 in FIG. 3. In this modification example, at least one of the rolling position S or the bending force F is selected as a control parameter. Therefore, in step S220, further, the influence coefficient of the added control parameter is calculated.

[0106] That is, in step S220, the first type of parallel rigidity setting calculated value E t and the influence coefficient ∂E / ∂P of the rolling load P on the first type of parallel rigidity setting calculated value E t and the influence coefficient ∂E / ∂F of the bending force F are calculated. Further, the arithmetic processing unit 200 calculates the influence coefficient of the control parameter selected in step S200, that is, the influence coefficient ∂E / ∂V of the roll speed V on the first type of parallel rigidity setting calculated value E t , the influence coefficient ∂E / ∂Q of the lubricant supply amount Q, the influence coefficient ∂E / ∂θ of the roll cross angle θ, the influence coefficient ∂E / ∂L of the roll shift amount L, and at least one of the influence coefficients ∂E / ∂C of the roll crown C is calculated. Further, at least one of the influence coefficient ∂E / ∂S of the rolling position S or the influence coefficient ∂E / ∂F of the bending force F is calculated. The influence coefficient ∂E / ∂S of the rolling position S is represented by the following formula (15).

[0107]

Equation

[0108] Step S230 in FIG. 11B may be implemented in the same manner as step S130 in FIG. 3.

[0109] (S240~S260: Control steps) When the first type of parallel rigidity actual calculated value E b is calculated in step S230, the meandering control device 100 determines whether to perform meandering control on the trailing end of the material to be rolled at the Mth stand based on the first type of parallel rigidity actual calculated value E b and the threshold value E THIt is determined by comparing them (S240). Step S240 may be implemented in the same manner as step S140 in FIG. 3.

[0110] The calculated value E of the first type of parallel rigidity achievement b is less than or equal to the threshold value E TH In the case where it is below (that is, when E b ≦ E TH ), since the degree of meandering of the trailing end portion of the material to be rolled is small, meandering control is not performed, and the process proceeds to step S270 described later.

[0111] On the other hand, when the calculated value E of the first type of parallel rigidity achievement b is greater than the threshold value E TH (that is, when E b > E TH ), since the degree of meandering of the trailing end portion of the material to be rolled is large, meandering control is performed. Therefore, first, the meandering control device 100 calculates the change amount ΔX of the control parameter selected in step S200 at the Mth stand in order to make the calculated value E of the first type of parallel rigidity achievement b less than or equal to the threshold value E TH . Step S250 may basically be implemented in the same manner as step S150 in FIG. 3, but further, the change amount of the added control parameter is calculated.

[0112] Specifically, regarding the change amount of the rolling reduction position S or the bending force F to be added, the meandering control device 100 calculates the control amount as follows, depending on whether to drive any of the increase bending devices 11a to 11d (furthermore, the decrease bending devices 12a to 12d) or the rolling reduction device 13 to perform meandering control. How to perform meandering control may be arbitrarily set within the range that satisfies the equipment constraints and the shape control constraints.

[0113] First, when performing meandering control by changing only the rolling reduction position by the rolling reduction device 13, the rolling reduction position change amount ΔS that satisfies the following formula (16) is calculated.

[0114]

Equation

[0115] Also, when performing snaking control by changing only the bending force F with the increase bending devices 11a to 11d (and further the decrease bending devices 12a to 12d), a bending force change amount ΔF that satisfies the following formula (17) is calculated.

[0116] [Number]

[0117] In addition, as control parameters, when a plurality of control parameters including at least any one of the roll speed V, lubricant supply amount Q, roll cross angle θ, roll shift amount L, and roll crown C, and at least one of the reduction position S or the bending force F are selected, as shown in the above formula (14), the sum of the products of the change amount ΔX of the selected control parameter X and the influence coefficient ∂E / ∂X is the first type of parallel rigidity actual calculation value E b and the threshold value E TH The change amount ΔX of each control parameter X is calculated as a control amount so that it is equal to or less than the difference from

[0118] When the control amount is calculated in step S250, the snaking control device 100 controls the control parameter X based on the calculated control amount (the change amount ΔX of the control parameter X) (S260). Thereby, snaking control of the tail end portion of the material to be rolled at the Mth stand is performed. Step S260 may be basically performed in the same manner as step S160 in FIG. 3, and further, the change amount of the added control parameter (at least one of the reduction position S or the bending force F) is calculated.

[0119] (S270: Confirmation of control amount change) Thereafter, it is confirmed whether there is a change in the control amount in the snaking control of the tail end portion (S270). Step S270 may be performed in the same manner as step S170 in FIG. 3.

[0120] The above described the meandering control example 1 according to the present embodiment. In the meandering control example 1, the first type parallel rigidity actual calculation value E b is calculated by obtaining in advance the first type parallel rigidity setting calculation value E t and the influence coefficient before rolling, thereby reducing the calculation load during rolling and enabling easy application to an actual machine. Further, since the calculated first type parallel rigidity actual calculation value E b is also estimated with high accuracy, it is possible to reduce the meandering amount at the trailing end of the material to be rolled, suppress the occurrence of drawing, and also reduce the thickness defect and shape defect of the material to be rolled after rolling.

[0121] [2-2. Meandering control example 2 (Calculation of the first type parallel rigidity actual calculation value using a model)] Next, based on FIGS. 12 and 13, as the meandering control example 2, the case of calculating the first type parallel rigidity actual calculation value using a model and performing meandering control on the trailing end of the material to be rolled will be described. FIG. 12 is a schematic diagram showing an outline of the calculation process of the first type parallel rigidity actual calculation value E b in the meandering control example 2. FIG. 13 is a flowchart showing the process of the meandering control example 2.

[0122] As shown in FIG. 12, the meandering control example 2 directly calculates the first type parallel rigidity actual calculation value E b using a model from the rolling conditions at the trailing end. That is, the meandering control example 2 does not calculate the first type parallel rigidity setting calculation value E t and the influence coefficient on the first type parallel rigidity as in the meandering control example 1, but calculates the first type parallel rigidity actual calculation value E b from the rolling conditions at the trailing end. Since the calculation using the model is a high-load calculation, the calculation processing time may be longer than that of the meandering control example 1, but the first type parallel rigidity actual calculation value E b can be calculated by one calculation process. Hereinafter, the meandering control example 2 will be described, but detailed description of the same processes as those in the meandering control example 1 will be omitted.

[0123] (S300: Selection of control parameters) As shown in FIG. 13, first, at least one of the roll speed V, lubricant supply amount Q, roll crossing angle θ, roll shift amount L, and roll crown C is used as a control parameter (S300). The control parameter can be selected based on the purpose of reducing the amount of meandering and emphasizing it in the meandering control at the trailing end of the material to be rolled, and the constraints in the equipment configuration of the rolling stand 10, as described above. Also, the selection of the control parameter may be performed by the operator, or the arithmetic processing unit may automatically select the control parameter. Step S300 may be implemented in the same manner as step S100 in FIG. 3.

[0124] (S310: Threshold setting step) Also, a threshold value E of the first type of parallel rigidity is set in advance before rolling such that the amount of meandering of the material to be rolled is less than the allowable value (S200). The setting of the threshold value E TH may be performed in the same manner as step S110 in FIG. 3. TH

[0125] (S320: First type of parallel rigidity calculation step) Next, an actual calculation value E of the first type of parallel rigidity is calculated. In the meandering control example 2, the arithmetic processing unit 200 calculates the actual calculation value E of the first type of parallel rigidity using a model from the rolling conditions of the trailing end of the material to be rolled at the Mth stand that is the control target (S320). Such calculation is performed based on the actual value of the rolling load P b and the actual value of the bending force F b and the actual value of the roll crossing angle θ b and the actual value of the roll shift amount L b and the actual value of the roll crown C b b b among the actual values of the control parameters selected in step S300.

[0126] The actual value of the rolling load P b and the actual value of the bending force F b are simultaneously acquired from when the leading end of the material to be rolled bites into the Mth stand until before the trailing end of the material to be rolled is rolled at the Mth stand. The actual value of the roll speed V b and the actual value of the lubricant supply amount Qb , actual value of roll cross angle θ b , actual value of roll shift amount L b , and actual value of roll crown C b may use the currently set value. For example, at the start of control, the initial set value is used, and when the value is changed in step S350 described later, the changed value is used.

[0127] Calculated value E of the first type of parallel rigidity b As a model for calculating, for example, the Mills stretch model can be used (see, for example, Non-Patent Document 2). Note that such calculations may also be performed using a model other than the Mills stretch model.

[0128] (S330~S350: Control steps) When the calculated value E of the first type of parallel rigidity is calculated in step S320 b , the snake control device 100 determines whether to perform snake control on the trailing end of the material to be rolled at the Mth stand by comparing the calculated value E of the first type of parallel rigidity b with the threshold value E TH (S330).

[0129] When the calculated value E of the first type of parallel rigidity b is less than or equal to the threshold value E TH (that is, when E b ≤ E TH ), since the degree of snake of the trailing end of the material to be rolled is small, snake control is not performed, and the process proceeds to step S360 described later.

[0130] On the other hand, when the calculated value E of the first type of parallel rigidity b is greater than the threshold value E TH (that is, when E b > E TH ), since the degree of snake of the trailing end of the material to be rolled is large, snake control is performed. The snake control may be performed in the same manner as steps S150 and S160 in FIG. 3. First, the snake control device 100 uses, as a control amount, the calculated value E of the first type of parallel rigidity b and the threshold value E THCalculate the change amount ΔX of the control parameter selected in step S300 at the Mth stand for the following purposes (S340). When the change amount is calculated, the meandering control device 100 controls the control parameter X based on the calculated change amount ΔX of the control parameter X (S350). Thereby, meandering control of the tail end portion of the material to be rolled at the Mth stand is performed.

[0131] (S360: Confirmation of change in control amount) Thereafter, it is confirmed whether there is a change in the control amount in the meandering control of the tail end portion (S360). Step S360 may be performed in the same manner as step S170 in FIG. 3. That is, the meandering control device 100 confirms whether there is a change in the control amount, and if there is no change, the process of FIG. 13 is terminated as it is. On the other hand, if there is a change in the control amount, the meandering control device 100 instructs the arithmetic processing device 200 to execute the process from step S320 again. The repetition of the processes of steps S320 to S350 may be performed, for example, until the update of the target value stops, or until the repetition process is performed a predetermined number of times. Thereby, the occurrence of meandering can be more reliably suppressed.

[0132] The meandering control example 2 has been described above. In the above description, in the meandering control example 1, as shown in FIG. 3, at least one of the roll speed V, the lubricant supply amount Q, the roll crossing angle θ, the roll shift amount L, and the roll crown C is selected as the control parameter in step S300. However, as in the modified example of the meandering control example 1 shown in FIGS. 11A and 11B, at least one of the reduction position S or the bending force F may be further selected as the control parameter.

Example

[0133] In order to confirm the effectiveness of the serpentine control of the trailing end of the material to be rolled according to this embodiment, the following verification was performed. In the verification, the narrowing occurrence rate and the trailing end yield loss rate were investigated when rolling a steel plate in a finishing tandem rolling mill composed of a plurality of rolling stands. The narrowing occurrence rate represents the occurrence ratio of narrowing caused by serpentine during trailing end rolling. Also, the trailing end yield loss rate represents the ratio at which the plate thickness of the rolled steel plate deviates from the target plate thickness.

[0134] The verification was performed for Comparative Examples 1 and 2 and the Example. Comparative Example 1 was the case where serpentine control was not performed on the trailing end of the steel plate, and Comparative Example 2 was the case where serpentine control of the trailing end of the steel plate was performed by the method of Patent Document 1. Also, as the Example, based on Serpentine Control Example 1 of the serpentine control method according to an embodiment of the present invention, serpentine control of the trailing end of the steel plate was performed. Table 1 below shows the verification results.

[0135]

Table 1

[0136] From Table 1 above, in Comparative Example 1, since serpentine control was not performed on the trailing end of the steel plate, serpentine occurred and narrowing occurred at 0.100%. In Comparative Example 2, as a result of performing serpentine control on the trailing end of the steel plate, the occurrence ratio of serpentine decreased compared to Comparative Example 1, and as a result, the narrowing occurrence rate decreased. However, the plate thickness accuracy of the trailing end deteriorated compared to Comparative Example 1.

[0137] On the other hand, in Examples 1 to 9 where the snake-like control of the tail end of the steel plate was performed based on Snake-like Control Example 1, the occurrence rate of snake-like movement decreased compared to Comparative Example 1. As a result, the occurrence rate of necking decreased. Also, the plate thickness accuracy at the tail end improved, and the yield loss rate at the tail end decreased. In Examples 1, 3, and 4, since the rolling reduction position, roll speed, and lubricant supply amount were used as control parameters, it is considered that the plate thickness defect at the tail end was reduced and the yield loss rate at the tail end decreased. In Examples 2 and 5 to 8, since the bending force, roll shift amount, roll cross angle, and roll crown were used as control parameters, it is considered that the occurrence of necking decreased. In Examples 8 and 9, since a control parameter with a high effect of reducing plate thickness defects and a control parameter with a high effect of preventing necking occurrence were used in combination, the occurrence rate of necking and the yield loss rate at the tail end could both be decreased compared to other examples.

[0138] As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

Explanation of Signs

[0139] 1 Upper working roll 2 Lower working roll 3 Upper reinforcing roll 4 Lower reinforcing roll 5 Upper working roll chuck 6 Lower working roll chuck 7 Upper reinforcing roll chuck 8 Lower reinforcing roll chuck 9 Housing 9a Inlet side project block 9b Outlet side project block 10 Rolling stand 11a~11d Increase bending device 12a~12d Decrease bending device 13 Pressing device 14 Rolling load detection device 100 Meandering control device 200 Arithmetic processing unit

Claims

1. In the rolling of a material to be rolled by N (N is a natural number) rolling stands, a method for controlling the meandering of the material to be rolled by controlling the meandering of the material to be rolled at the M-th stand (1 ≤ M ≤ N), comprising: The control parameter for the meandering control is at least one of a roll speed V, a lubricant supply amount Q, a roll cross angle θ, a roll shift amount L, and a roll crown C; A threshold setting step of setting, in advance, a threshold value E of a first type of parallel rigidity at the Mth stand such that the amount of tail-end meandering of the material to be rolled is less than an allowable value ＴＨ and a threshold value setting step The first type of parallel stiffness calculation value E at the M-th stand ｂ A first type of parallel stiffness calculation step for calculating the value the first type of parallel rigidity calculation value E ｂ is less than or equal to the threshold value E ＴＨ in which case, the control parameter is not changed the first type of parallel rigidity actual calculation value E ｂ is greater than the threshold value E ＴＨ If it is larger, Based on the first type of parallel rigidity actual calculation value E ｂ calculate the change amount of the control parameter of the M-th stand to make the first type of parallel rigidity equal to or less than the threshold value E ＴＨ ​ A control step of controlling the control parameter of the M-th stand corresponding to the change amount based on the calculated change amount of the control parameter while the tail end of the material to be rolled passes through the M-th stand; A method for controlling the meandering of a material to be rolled, including the above steps.

2. The method for controlling the meandering of a material to be rolled according to claim 1, further using at least one of a rolling reduction position or a bending force as the control parameter.

3. In the first type of parallel rigidity calculation step, the actual rolling load value P ｂ and the actual bending force value F ｂ at the M-th stand, which are simultaneously acquired between the time when the tip of the material to be rolled bites into the M-th stand and the time before the trailing end of the material to be rolled is rolled at the M-th stand, and based on the actual value of the control parameter, the first type of parallel rigidity actual calculation value E ｂ is calculated. The method for controlling the meandering of the material to be rolled according to claim 1 or 2.

4. In the first type of parallel rigidity calculation step, By setup calculation, the rolling load set value P at the Mth stand ｔ and the bending force set value F ｔ and the set value of the control parameter are calculated, The first type of parallel stiffness setting calculation value E at the Mth stand ｔ Calculate the influence coefficient ∂E / ∂P of the rolling load, the influence coefficient ∂E / ∂F of the bending force, and the influence coefficient of the control parameter with respect to E, The rolling load actual value P at the Mth stand, which is simultaneously acquired between when the tip of the material to be rolled bites into the Mth stand and before the trailing end of the material to be rolled is rolled at the Mth stand ｂ and the bending force actual value F ｂ Based on the actual values of the control parameters and the actual values of the setting values, difference values between the setting values and the actual values are respectively calculated Based on the difference value and the influence coefficient, the first type of parallel rigidity actual calculation value E at the Mth stand is calculated. ｂ The method for controlling the meandering of the material to be rolled according to claim 1 or 2, which calculates this.

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