Thickness Control Method and Control Device for an 18-High Rolling Mill

Abstract

The embodiment of this specification discloses a thickness control method for an eighteen-roll mill, after the entry thickness gauge moves a first set length toward the frame of the eighteen-roll mill, and the exit thickness gauge moves a second set length toward the frame, if the first tracking point of the entry thickness gauge reaches the frame, the second flow feedforward control is started; after starting the second flow feedforward control, the second tracking point is started; when the tracking distance of the second tracking point reaches a set distance, the second flow feedback control is started, wherein the set distance is set according to the interval distance between the eighteen-roll mill and the exit thickness gauge. The thickness control method and control device for an eighteen-roll mill disclosed in this specification can effectively shorten the thickness fluctuation length when the lead is started, improve the thickness control accuracy, and thus effectively improve the yield rate.

Description

Technical Field

[0001] The embodiments of this specification relate to the technical field of rolling mills, and in particular to a thickness control method and control device for an eighteen-high rolling mill. Background Art

[0002] In the prior art, the main method of thickness control for the 18-roller stand is the second flow AGC, which is used to keep the second flow constant between the stands during steady-state rolling, that is, the second flow at the stand entrance should be equal to the second flow at the exit. The stand exit thickness is estimated based on the principle of equal second flow, and the thickness is compared with the target thickness to obtain the exit thickness deviation, and then the thickness deviation is eliminated by adjusting the roll gap of the stand. However, due to the large thickness fluctuation of the 18-roller stand when starting the machine, the increase in the thickness fluctuation length will lead to a decrease in the stand yield rate. Summary of the invention

[0003] The embodiments of this specification provide a thickness control method and control device for an 18-roller rolling mill, which can effectively shorten the thickness fluctuation length when the lead mill is started, improve the thickness control accuracy, and thus effectively improve the yield rate.

[0004] A first aspect of an embodiment of the present specification provides a thickness control method for an 18-high rolling mill, the method comprising:

[0005] After the inlet thickness gauge is moved toward the frame of the 18-high rolling mill by a first set length and the outlet thickness gauge is moved toward the frame by a second set length, if the first tracking point of the inlet thickness gauge reaches the frame, the second flow rate feedforward control is started;

[0006] After starting the second flow rate feedforward control, starting the second tracking point;

[0007] When the tracking distance of the second tracking point reaches a set distance, the second flow rate feedback control is started, wherein the set distance is set according to the interval distance between the 18-roller rolling mill and the exit thickness gauge.

[0008] Optionally, after the first tracking point of the inlet thickness gauge reaches the rack and before starting the second flow feedforward control, the method further comprises:

[0009] The first pass, the second pass and the last pass of the 18-high rolling mill are filled with a preset thickness, wherein the preset thickness filling includes any one of an entry set thickness filling and an average thickness filling;

[0010] The remaining passes of the 18-roll mill are filled by inverted thickness filling, wherein the inverted thickness filling is filled after reverse reading of the strip thickness recorded in the thickness record database, and the remaining passes are the passes in the 18-roll mill except the first pass, the second pass and the last pass.

[0011] Optionally, after the first tracking point of the entrance thickness gauge reaches the rack and before starting the second flow rate feedforward control, the method further includes:

[0012] Adopting the preset thickness filling for the first pass, the second pass, and the last pass of the eighteen-high rolling mill;

[0013] Adopting the entrance set thickness filling for the remaining passes of the eighteen-high rolling mill.

[0014] Optionally, after starting the second flow rate feedforward control, the method further includes:

[0015] Obtaining a feedforward thickness difference according to the second flow rate feedforward control;

[0016] Obtaining a feedback thickness difference according to the second flow rate feedforward control;

[0017] Within a set duration after starting the second flow rate feedforward control, determining whether the product of the thickness differences between the feedforward thickness difference and the feedback thickness difference is not greater than a set value;

[0018] If the product of the thickness differences is not greater than the set value, prohibit enabling the second flow rate feedback control.

[0019] Optionally, after determining whether the product of the thickness differences between the feedforward thickness difference and the feedback thickness difference is not greater than the set value, the method further includes:

[0020] If the product of the thickness differences is greater than the set value, enable the second flow rate feedback control.

[0021] Optionally, after starting the second flow rate feedback control, the method further includes:

[0022] Detecting whether there is uncoiling and tail flicking;

[0023] When detecting the existence of the uncoiling and tail flicking, starting the tail roll gap compensation control.

[0024] Optionally, the detecting whether there is uncoiling and tail flicking includes:

[0025] Obtaining the tension change value of the eighteen-high rolling mill;

[0026] Determining whether the tension change value is less than a set change value;

[0027] If it is determined that the tension change value is less than the set change value, it is detected that there is uncoiling and tail flicking.

[0028] Optionally, the starting the tail roll gap compensation control when detecting the uncoiling and tail flicking includes:

[0029] When the uncoiler tail swing is detected, obtain the rolling force increment of the eighteen-high rolling mill;

[0030] According to the rolling force increment, obtain the roll gap compensation amount;

[0031] Use the roll gap compensation amount to control the roll gap of the eighteen-high rolling mill.

[0032] The second aspect of the embodiments of this specification provides a thickness control device for an eighteen-high rolling mill, and the device includes:

[0033] A feedforward control unit, configured to start the second-by-second flow feedforward control if, after the entrance thickness gauge moves a first set length towards the stand of the eighteen-high rolling mill and the exit thickness gauge moves a second set length towards the stand, the first tracking point of the entrance thickness gauge reaches the stand;

[0034] A tracking start unit, configured to start the second tracking point after starting the second-by-second flow feedforward control;

[0035] A feedback control unit, configured to start the second-by-second flow feedback control when the tracking distance of the second tracking point reaches a set distance, where the set distance is set according to the interval distance between the eighteen-high rolling mill and the exit thickness gauge.

[0036] Optionally, it further includes:

[0037] A thickness filling unit, configured to perform a preset thickness filling on the first pass, the second pass, and the last pass of the eighteen-high rolling mill after the first tracking point of the entrance thickness gauge reaches the stand and before starting the second-by-second flow feedforward control, where the preset thickness filling includes any one of an entrance set thickness filling and an average thickness filling; and perform a thickness inversion filling on the remaining passes of the eighteen-high rolling mill, where the thickness inversion filling is filling after reading the strip thickness recorded in the thickness record database in reverse, and the remaining passes are the passes of the eighteen-high rolling mill other than the first pass, the second pass, and the last pass.

[0038] The beneficial effects of the embodiments of this specification are as follows:

[0039] Based on the above technical solution, after the entrance thickness gauge moves the first set length toward the frame of the eighteen-roll rolling mill and the exit thickness gauge moves the second set length toward the frame, if the first tracking point of the entrance thickness gauge reaches the frame, the second flow feedforward control is started; after starting the second flow feedforward control, the second tracking point is started; when the tracking distance of the second tracking point reaches the set distance, the second flow feedback control is started; in this way, the entrance thickness gauge tracking point starts to move after the frame is started, and the second flow feedforward control is started when the entrance thickness gauge tracking point reaches the frame, and since the entrance thickness gauge moves the first set length toward the frame, compared with the prior art, the second flow feedforward control can be started faster after the frame is started, thereby effectively shortening the thickness fluctuation length when the lead is started, improving the thickness control accuracy, and thus effectively improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a method flow chart of the thickness control method of the 18-high rolling mill in the embodiment of this specification;

[0041] Figure 2 It is a schematic diagram of the structure of the thickness control device of the eighteen-roll rolling mill in the embodiment of this specification. DETAILED DESCRIPTION

[0042] In order to better understand the above technical scheme, the technical scheme of the embodiments of this specification is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical scheme of the embodiments of this specification, rather than limitations on the technical scheme of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0043] Reference Figure 1 A thickness control method of an 18-high rolling mill of the present invention is shown, the method comprising:

[0044] S101, after the inlet thickness gauge moves toward the frame of the 18-high rolling mill by a first set length and the outlet thickness gauge moves toward the frame by a second set length, if the first tracking point of the inlet thickness gauge reaches the frame, start the second flow rate feedforward control;

[0045] S102, after starting the second flow rate feedforward control, starting the second tracking point;

[0046] S103. When the tracking distance of the second tracking point reaches a set distance, start the second flow rate feedback control, wherein the set distance is set according to the interval distance between the 18-roller rolling mill and the exit thickness gauge.

[0047] The thickness control method of the eighteen-roll rolling mill in the embodiment of this specification can be applied to a server connected to the eighteen-roll rolling mill. The server can be, for example, a tablet computer, a laptop, an all-in-one computer, a desktop computer, etc.

[0048] Among them, in step S101, the entrance thickness gauge can be gradually moved forward to the frame, so that the entrance thickness gauge moves toward the frame by a first set length; the exit thickness gauge can also be gradually moved forward to the frame, so that the exit thickness gauge moves toward the frame by a second set length, wherein the first set length and the second set length can be set according to actual needs, and can also be set manually or by the equipment. The first set length can be, for example, 10 millimeters (mm), 20 mm, and 50 mm, etc., and the second set length can be, for example, 10 mm, 30 mm, and 60 mm, etc.

[0049] After the entrance thickness gauge is moved to the frame by the first set length, at this time, if the frame is started, the first tracking point of the entrance thickness gauge can track the strip faster. In this way, when the first tracking point of the entrance thickness gauge reaches the frame, the time from the start of the frame to the first tracking point reaching the frame will be shorter. When the first tracking point reaches the frame, the second flow feedforward control can be started, so that the time from the start of the frame to the start of the second flow feedforward control will also be shorter, thereby prompting the second flow feedforward control to be started faster after the frame is started, thereby effectively shortening the thickness fluctuation length when the strip is started, improving the thickness control accuracy, and thus effectively improving the yield rate.

[0050] In the embodiment of this specification, the thickness control method of the 18-high rolling mill specifically uses the thickness automatic control (Automatic Gauge Control, AGC) system, wherein the second flow feedforward control is the AGC feedforward control, and the second flow feedback control is the AGC feedback control. At this time, the AGC feedforward control is based on the change in the thickness of the inlet strip, and the roll gap correction amount is sent to the correction cylinder of the frame, and the acceleration correction amount is sent to the speed parameter to improve the effectiveness of the roll gap correction. This control can quickly eliminate the impact of the inlet thickness change on the thickness of the outlet strip. The second flow control is to calculate the outlet thickness based on the speed of the strip inlet and outlet and the thickness of the strip inlet, and compare the calculated outlet thickness with the actual set value to obtain the theoretical thickness deviation value, send the modified acceleration to the speed parameter, and send the roll gap correction amount to the pressing cylinder to maintain the internal tension. AGC feedback control measures the deviation between the thickness of the outlet and the actual set outlet thickness. The deviation signal is processed by the predictor, which plays the role of the transmission time from the roll bite of the stand to the thickness gauge. The controller generates the corrected speed, which is sent to the adjacent stand speed parameter. At the same time, the roll gap correction is sent to the pressing cylinder to maintain the tension between the stands. Eccentricity compensation is mainly to eliminate the influence of uneven roll surface hardness or eccentricity on thickness.

[0051] In another embodiment of this specification, in order to further advance the second flow rate feedforward control, after the first tracking point of the entrance thickness gauge reaches the rack and before starting the second flow rate feedforward control, the first pass, the second pass, and the last pass of the eighteen-roll mill can be filled with a preset thickness, where the preset thickness filling includes any one of the entrance set thickness filling and the average thickness filling; the remaining passes of the eighteen-roll mill are filled with thickness inversion filling, where the thickness inversion filling is filling after reading the strip thickness recorded in the thickness record database in reverse, and the remaining passes are the passes of the eighteen-roll mill except for the first pass, the second pass, and the last pass.

[0052] Among them, the thickness inversion filling means that if the entrance thickness gauge records the strip thickness measured in the forward direction, then at the exit, the strip thickness read in the forward direction is read in reverse. For example, if the strip thicknesses recorded in the forward direction are A1, A2, A3, and A4 in sequence, then the thickness inversion filling is filled with A4, A3, A2, and A1 in sequence.

[0053] Specifically, after the first tracking point of the entrance thickness gauge reaches the rack and before starting the second flow rate feedforward control, the first pass, the second pass, and the last pass of the eighteen-roll mill can be filled with a preset thickness; the remaining passes of the eighteen-roll mill are filled with the entrance set thickness.

[0054] Since the first pass, the second pass, and the last pass are filled with the entrance set thickness or the average thickness, and the remaining passes are filled with the exit micro-tracking loop array inversion filling or the entrance set thickness filling, after the thickness filling, the second flow rate feedforward control and the second flow rate feedback control can be immediately put into operation as soon as the rack starts up to 30 mpm, so as to realize further advancing the second flow rate control.

[0055] After starting the second flow rate feedforward control, step S102 is executed.

[0056] In step S102, after starting the second flow rate feedforward control, the entrance thickness gauge is controlled to start the second tracking point.

[0057] After starting the second tracking point, if the tracking distance of the second tracking point reaches the set distance, step S103 is executed.

[0058] After executing step S102 and before executing step S103, it is also necessary to obtain the tracking distance of the second tracking point, which can be obtained in real time or at intervals, such as obtaining once every 10 ms, 20 ms, and 30 ms (milliseconds), and then judging whether the tracking distance of the second tracking point reaches the set distance, where the set distance is set according to the interval distance between the eighteen-roll mill and the exit thickness gauge.

[0059] At this time, the set distance can be the interval distance, or the product of the interval distance and a weight, or the sum or difference between the interval distance and a fixed value, etc. This specification does not make any specific restrictions.

[0060] In step S103, when the tracking distance reaches the set distance, the second flow feedback control is started.

[0061] In another embodiment of the present specification, after starting the second flow feedforward control and before starting the second flow feedback control, the feedforward thickness difference can be obtained according to the second flow feedforward control; the feedback thickness difference can be obtained according to the second flow feedforward control; within the set time after starting the second flow feedforward control, it is determined whether the thickness difference product of the feedforward thickness difference and the feedback thickness difference is not greater than the set value; if the thickness difference product is not greater than the set value, the second flow feedback control is prohibited; if the thickness difference product is greater than the set value, the second flow feedback control is enabled.

[0062] Among them, the set duration can be set according to actual conditions, or it can be set manually or by the device itself, and the set duration can be, for example, 10 seconds, 15 seconds, 20 seconds, and 30 seconds, etc.; further, the set value can be set according to actual conditions, or it can be set manually or by the device itself, and the set value can be, for example, 0, 1, and 2, etc.

[0063] In actual application, second flow control requires micro-tracking. The inlet micro-tracking will gradually move the actual thickness of the inlet thickness gauge toward the frame, and the outlet micro-tracking will gradually move the outlet thickness gauge toward the frame. In the classic second flow control, the inlet thickness gauge tracking point starts to move after the frame is started. When the inlet thickness gauge tracking point reaches the frame, the second flow feedforward control is started (the purpose is to ensure the effective thickness of the rolling mill entrance), and then a new tracking is started. When the new tracking distance reaches the distance between the rolling mill and the outlet thickness gauge, the second flow feedback control is started. In this way, the second flow feedforward control is started 6.88 seconds after the frame starts and reaches 30mpm, and the second flow feedback control is started 14.059 seconds after the frame starts and reaches 30mpm. The lead out-of-tolerance length is 5.045m, but in the prior art, the out-of-tolerance length of the strip is longer when the machine is started, and the thickness fluctuation of the coil is more than 20 meters. In this way, compared with the prior art, the thickness control method provided by the present application enables the second flow feedforward control to be started more quickly after the frame is started, thereby effectively shortening the thickness fluctuation length when the lead is started, improving the thickness control accuracy, and thus effectively improving the yield rate.

[0064] In another embodiment of the present application, in order to further advance the second-by-second flow control, it is necessary to actively intervene in the inlet micro-tracking loop array. The first pass, the second pass, and the last pass are filled with the inlet set thickness or the average thickness, and the remaining passes are filled with the inverted outlet micro-tracking loop array and also use the inlet set thickness for filling. After such processing, the second-by-second flow feedforward control and the second-by-second flow feedback control can be immediately put into operation when the first stand starts up to 30 mpm. However, during the start-up phase of the stand, when the second-by-second flow feedforward control and the feedback control are simultaneously put into operation, conflicts will occur between the second-by-second flow feedforward control and the feedback control. Therefore, by calculating the thickness difference product of the feedforward thickness difference and the feedback thickness difference, within a set time period after start-up, such as 20 s or 15 s, if the thickness difference product is greater than 0, the second-by-second flow feedback control is allowed to be put into operation.

[0065] Moreover, in order to avoid overshoot of the start-up thickness difference, the second-by-second flow feedforward control gain varies with the feedforward thickness difference, and the gain decreases as the feedforward thickness difference decreases; while the second-by-second flow feedback control gain varies with the feedback thickness difference, that is, the gain decreases as the feedback thickness difference decreases. In order to further reduce the inlet over-tolerance length, the feedforward thickness difference limit can be gradually relaxed, from 20 um to 35 um gradually. During this process, it is necessary to relax according to the actual situation to prevent the deviation and breakage accidents caused by the rapid pressing down of the start-up second-by-second flow control.

[0066] In another embodiment of the present application, after starting the second-by-second flow feedback control, it is also possible to detect whether there is a tail flick during uncoiling; when it is detected that there is a tail flick during uncoiling, the tail roll gap compensation control is started.

[0067] Specifically, when detecting whether there is a tail flick during uncoiling, the tension change value of the eighteen-roll mill can be obtained; it is judged whether the tension change value is less than the set change value; if it is judged that the tension change value is less than the set change value, it is detected that there is a tail flick during uncoiling; if it is judged that the tension change value is not less than the set change value, it is detected that there is no tail flick during uncoiling.

[0068] Specifically, when detecting a tail flick during uncoiling, the rolling force increment of the eighteen-roll mill is obtained; according to the rolling force increment, the roll gap compensation amount is obtained; and the roll gap of the eighteen-roll mill is controlled by using the roll gap compensation amount.

[0069] In the embodiments of this specification, since the incoming steel coil is first loaded on the uncoiler for uncoiling, when the tail end leaves the uncoiler (i.e., there is a tail flick during uncoiling), the inlet tension is suddenly lost, resulting in a sudden increase in the outlet thickness difference. Therefore, when there is a tail flick during uncoiling, it is necessary to start the tail roll gap compensation control to reduce the probability of the sudden increase in the outlet thickness difference.

[0070] In the embodiments of this specification, the set change value can be set according to the actual situation, or can be set manually or by the device itself. The set change value can be, for example, -20%, -25%, -30%, etc.

[0071] In another embodiment, in order to further improve the accuracy of detecting unwinding tail swing, it is also possible to determine whether the tension change value within a preset time is less than the set change value. The preset time can be, for example, 80ms, 60ms, and 90ms. In this way, if the tension change value within the preset time is less than the set change value, the unwinding tail swing signal is detected; otherwise, the unwinding tail swing signal is not detected; when the unwinding tail swing signal is detected, the second flow feedforward and feedback control are immediately cut off, that is, the second flow feedforward and feedback control are prohibited, which is beneficial to the strip tail thickness control. In addition, in order to suppress the increase of the outlet thickness difference caused by unwinding tail swing, the roll gap must be compensated in real time. At this time, the partial derivative of the actual rolling force to the inlet ratio can be calculated, and then the increment of the actual rolling force is calculated, and then the roll gap compensation amount is calculated using the PH diagram.

[0072] The partial derivative of the actual rolling force with respect to the inlet tension ratio refers to the change in rolling force caused by a unit change in the inlet tension ratio when other factors remain unchanged. The calculation formula of the rolling force is as follows:

[0073]

[0074] Where, in formula 1, P represents the rolling force, represents the average deformation resistance, n t represents the tension factor, B represents the strip width, R′ represents the flattening radius, H represents the inlet thickness, h represents the outlet thickness, Q p represents the friction factor.

[0075] In this way, the increment of the actual rolling force can be calculated using Formula 1. After the increment is calculated, the roll gap compensation amount is calculated using the PH diagram, and the roll gap compensation is performed using the roll gap compensation amount.

[0076] The beneficial effects of the embodiments of this specification are as follows:

[0077] Based on the above technical solution, after the entrance thickness gauge moves the first set length toward the frame of the eighteen-roll rolling mill and the exit thickness gauge moves the second set length toward the frame, if the first tracking point of the entrance thickness gauge reaches the frame, the second flow feedforward control is started; after starting the second flow feedforward control, the second tracking point is started; when the tracking distance of the second tracking point reaches the set distance, the second flow feedback control is started; in this way, the entrance thickness gauge tracking point starts to move after the frame is started, and the second flow feedforward control is started when the entrance thickness gauge tracking point reaches the frame, and since the entrance thickness gauge moves the first set length toward the frame, compared with the prior art, the second flow feedforward control can be started faster after the frame is started, thereby effectively shortening the thickness fluctuation length when the lead is started, improving the thickness control accuracy, and thus effectively improving the yield rate.

[0078] Based on the thickness control method of an eighteen-high rolling mill provided above, an embodiment of this specification also provides a thickness control device for an eighteen-high rolling mill, as Figure 2 shown, the device includes:

[0079] A feedforward control unit 201, configured to start the second-by-second flow feedforward control if, after the entrance thickness gauge moves a first set length towards the stand of the eighteen-high rolling mill and the exit thickness gauge moves a second set length towards the stand, when the first tracking point of the entrance thickness gauge reaches the stand;

[0080] A tracking start unit 202, configured to start a second tracking point after starting the second-by-second flow feedforward control;

[0081] A feedback control unit 203, configured to start the second-by-second flow feedback control when the tracking distance of the second tracking point reaches a set distance, where the set distance is set according to the interval distance between the eighteen-high rolling mill and the exit thickness gauge.

[0082] In an alternative embodiment, it further includes:

[0083] A thickness filling unit, configured to, after the first tracking point of the entrance thickness gauge reaches the stand and before starting the second-by-second flow feedforward control, perform a preset thickness filling on the first pass, the second pass, and the last pass of the eighteen-high rolling mill, where the preset thickness filling includes any one of an entrance set thickness filling and an average thickness filling; and perform a thickness inversion filling on the remaining passes of the eighteen-high rolling mill, where the thickness inversion filling is filling after reading the strip thickness recorded in the thickness record database in reverse, and the remaining passes are the passes of the eighteen-high rolling mill other than the first pass, the second pass, and the last pass.

[0084] In an alternative embodiment, the thickness filling unit is configured to, after the first tracking point of the entrance thickness gauge reaches the stand and before starting the second-by-second flow feedforward control, perform the preset thickness filling on the first pass, the second pass, and the last pass of the eighteen-high rolling mill; and perform an entrance set thickness filling on the remaining passes of the eighteen-high rolling mill.

[0085] In an alternative embodiment, the feedback control unit 203 is configured to, after starting the second-by-second flow feedforward control, obtain a feedforward thickness difference according to the second-by-second flow feedforward control; obtain a feedback thickness difference according to the second-by-second flow feedforward control; within a set time period after starting the second-by-second flow feedforward control, determine whether the thickness difference product between the feedforward thickness difference and the feedback thickness difference is not greater than a set value; if the thickness difference product is not greater than the set value, prohibit enabling the second-by-second flow feedback control.

[0086] In an alternative embodiment, the feedback control unit 203 is configured to, after determining whether the product of the feedforward thickness difference and the feedback thickness difference is not greater than a set value, if the product of the thickness differences is greater than the set value, enable the second flow rate feedback control.

[0087] In an alternative embodiment, it further includes:

[0088] A tail flick control unit, configured to, after starting the second flow rate feedback control, detect whether there is an uncoiler tail flick; when detecting the uncoiler tail flick, start the tail roll gap compensation control.

[0089] In an alternative embodiment, the tail flick control unit is configured to obtain the tension change value of the eighteen-high rolling mill; determine whether the tension change value is less than a set change value; if it is determined that the tension change value is less than the set change value, then detect the uncoiler tail flick.

[0090] In an alternative embodiment, the tail flick control unit is configured to, when detecting the uncoiler tail flick, obtain the rolling force increment of the eighteen-high rolling mill; obtain the roll gap compensation amount according to the rolling force increment; use the roll gap compensation amount to control the roll gap of the eighteen-high rolling mill.

[0091] Although the preferred embodiments of this specification have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of this specification.

[0092] Obviously, those skilled in the art can make various changes and modifications to this specification without departing from the spirit and scope of this specification. Thus, if these modifications and variations of this specification fall within the scope of the claims of this specification and their equivalent technologies, this specification is also intended to include these modifications and variations.

Claims

1. A thickness control method for an eighteen-high rolling mill, characterized in that, the method includes: After the entrance thickness gauge moves a first set length towards the frame of the eighteen-high rolling mill and the exit thickness gauge moves a second set length towards the frame, if the first tracking point of the entrance thickness gauge reaches the frame, start the second flow rate feedforward control; After starting the second flow rate feedforward control, start the second tracking point; When the tracking distance of the second tracking point reaches the set distance, start the second flow rate feedback control, where the set distance is set according to the interval distance between the eighteen-high rolling mill and the exit thickness gauge; After the first tracking point of the entrance thickness gauge reaches the frame and before starting the second flow rate feedforward control, the method further includes: Adopting a preset thickness filling for the first pass, the second pass and the last pass of the eighteen-high rolling mill, where the preset thickness filling includes any one of the entrance set thickness filling and the average thickness filling; Adopting a thickness inversion filling for the remaining passes of the eighteen-high rolling mill, where the thickness inversion filling is the filling after the strip thickness recorded in the thickness record database is read in reverse, and the remaining passes are the passes of the eighteen-high rolling mill other than the first pass, the second pass and the last pass; After starting the second flow rate feedback control, the method further includes: Detecting whether there is uncoiling and tail flicking; When it is detected that there is uncoiling and tail flicking, start the tail roll gap compensation control; The detecting whether there is uncoiling and tail flicking includes: Obtaining the tension change value of the eighteen-high rolling mill; Judging whether the tension change value is less than the set change value; If it is judged that the tension change value is less than the set change value, it is detected that there is uncoiling and tail flicking.

2. The thickness control method according to claim 1, characterized in that, After the first tracking point of the entrance thickness gauge reaches the frame and before starting the second flow rate feedforward control, the method further includes: Adopting the preset thickness filling for the first pass, the second pass and the last pass of the eighteen-high rolling mill; Adopting the entrance set thickness filling for the remaining passes of the eighteen-high rolling mill.

3. The thickness control method according to claim 1, characterized in that, After starting the second flow rate feedforward control, the method further includes: Obtaining the feedforward thickness difference according to the second flow rate feedforward control; Obtaining the feedback thickness difference according to the second flow rate feedforward control; Within a set time period after starting the second flow rate feedforward control, judging whether the thickness difference product of the feedforward thickness difference and the feedback thickness difference is not greater than the set value; If the thickness difference product is not greater than the set value, prohibit enabling the second flow rate feedback control.

4. The thickness control method according to claim 1, characterized in that, After judging whether the thickness difference product of the feedforward thickness difference and the feedback thickness difference is not greater than the set value, the method further includes: If the thickness difference product is greater than the set value, enable the second flow rate feedback control.

5. The thickness control method according to claim 1, characterized in that, The starting the tail roll gap compensation control when it is detected that there is uncoiling and tail flicking includes: When the uncoiler tail swing is detected, obtain the rolling force increment of the eighteen-high rolling mill; Obtain the roll gap compensation amount according to the rolling force increment; Control the roll gap of the eighteen-high rolling mill by using the roll gap compensation amount.

6. A thickness control device for an eighteen-high rolling mill, characterized in that, the device includes: A feedforward control unit, configured to start the second flow rate feedforward control if the first tracking point of the entrance thickness gauge reaches the rolling mill stand after the entrance thickness gauge moves a first set length towards the rolling mill stand of the eighteen-high rolling mill and the exit thickness gauge moves a second set length towards the rolling mill stand; A tracking start unit, configured to start the second tracking point after starting the second flow rate feedforward control; A feedback control unit, configured to start the second flow rate feedback control when the tracking distance of the second tracking point reaches a set distance, where the set distance is set according to the interval distance between the eighteen-high rolling mill and the exit thickness gauge; The thickness control device further includes: A thickness filling unit, configured to perform a preset thickness filling on the first pass, the second pass, and the last pass of the eighteen-high rolling mill after the first tracking point of the entrance thickness gauge reaches the rolling mill stand and before starting the second flow rate feedforward control, where the preset thickness filling includes any one of an entrance set thickness filling and an average thickness filling; and perform a thickness inversion filling on the remaining passes of the eighteen-high rolling mill, where the thickness inversion filling is filling after reading the strip thickness recorded in the thickness record database in reverse, and the remaining passes are the passes of the eighteen-high rolling mill other than the first pass, the second pass, and the last pass.

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