How to change the running thickness

Abstract

Provided is a method for changing running sheet thickness, with which it is possible to shorten sheet-thickness off-gauge length and reduce tension fluctuation. This method for changing running sheet thickness is for continuous rolling of a rolling target material (6) in which a leading material (61) and a succeeding material (62), which are metal sheets, are joined by a tandem mill 2. In this method, the sheet thickness or the sheet speed of the rolling target material 6 is continuously measured in a target stand interval between a subject stand (e.g., second stand (2B)) which is a rolling stand where the sheet thickness is changed and a preceding-stage stand (e.g., first stand (2A)) which is a rolling stand in a stage preceding to the subject stand. A sheet-thickness changing position in the vicinity of a joint portion between the leading material (61) and the succeeding material (62) is detected from a sheet-thickness measurement result or tracked from a sheet-speed measurement result. Then, at the timing when said sheet-thickness changing position reaches the subject stand, the roll gap of the subject stand is changed.

Description

[Technical field]

[0001] The present invention relates to a method for varying a running gauge. [Background technology]

[0002] In cold rolling of steel plates, a technique called "flying thickness change" is used to continue rolling without stopping the rolling mill as much as possible in order to improve efficiency and yield. Flying thickness change is a method for rolling continuously without stopping the rolling mill when rolling welds of coils with different specifications by continuously changing the actuator settings from the preceding coil to the following coil. When changing the actuator settings for the flying thickness change, it takes time to change the settings, especially when the amount of change in the reduction position, etc. is large, so the steady state is temporarily broken, causing the tension to become unstable and resulting in plate breakage, etc.

[0003] Conventionally, a method of providing an intermediate thickness has been used as a method of suppressing tension fluctuations when changing the thickness while traveling. For example, Patent Document 1 discloses a method of determining an intermediate thickness to suppress tension fluctuations by creating an evaluation function with the thickness fluctuation amount as a variable and determining the intermediate thickness so that the evaluation function falls within a certain threshold value. Patent Document 2 also discloses a means of suppressing tension fluctuations by determining a value of tension fluctuations and resetting the time of changing the thickness while traveling in which the set values ​​of the roll gap and the roll peripheral speed are changed from pass schedule A to pass schedule B. In Patent Document 2, the value of tension fluctuations is determined based on the tension fluctuation value predicted by a tension fluctuation learning means using a neural network that has learned the tension fluctuations during the actual thickness change while traveling as teacher data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-12423 [Patent Document 2] Japanese Patent Application Publication No. 10-249423 Summary of the Invention [Problem to be solved by the invention]

[0005] Due to recent technological innovations and the expansion of steel sheet applications, various steel sheets (especially high deformation resistance materials such as electromagnetic materials and high tensile steel) are now being rolled, and thickness changes while the coils are connected, which have significantly different specifications (plate thickness, deformation resistance, etc.), have become necessary. As a result, tension fluctuations during thickness changes while the coils are being connected have become large, and solutions using conventional technologies such as those mentioned above have been attempted.

[0006] However, the method of Patent Document 1 has a problem in that the off-gauge length is long because an intermediate thickness is provided. In addition, the method of Patent Document 2 does not necessarily take into account the influence of the changes in rolling conditions before and after the joint, such as the difference in thickness and the difference in deformation resistance between the preceding and succeeding materials, which affect the tension fluctuation when passing through the joint. For this reason, the method of Patent Document 2 has low prediction accuracy of tension fluctuation, and there are cases where the tension fluctuation is large.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned problems, and has an object to provide a method for varying thickness while traveling, which can reduce tension fluctuations. [Means for solving the problem]

[0008] (1) According to one aspect of the present invention, there is provided a method for changing a thickness of a rolled material, which is a joint between a leading material and a trailing material that are metal plates, when the rolled material is continuously rolled by a tandem rolling mill, the method comprising: continuously measuring a thickness or a speed of the rolled material between a target stand, which is a rolling stand that performs the thickness change, and a preceding stand, which is a rolling stand preceding the target stand; detecting a thickness change position near the joint between the leading material and the trailing material from the thickness measurement results or tracking the thickness change position from the speed measurement results; and changing the roll gap of the target stand at a timing when the thickness change position reaches the target stand.

[0009] (2) In the configuration of (1) above, the length of the tapered plate thickness portion after rolling in the preceding stand is calculated using the plate speed measured between the target stands, the length of the tapered plate thickness portion is divided by the amount of change in the reduction position in the target stand to calculate the rate of change in the reduction position, and the roll gap of the target stand is changed by the calculated rate of change.

[0010] (3) In the above configuration (1) or (2), the material to be rolled is a high deformation resistance steel plate. Effect of the Invention

[0011] According to one aspect of the present invention, there is provided a method for varying a thickness while running, which can reduce tension fluctuations. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a cold rolling facility in a first embodiment of the present invention. [Diagram 2] FIG. 1 is an explanatory diagram showing a conventional method of changing thickness while traveling, where (A) shows the state where the thickness changing position S1 is upstream of the first stand, (B) shows the state where the thickness changing position S1 has reached the first stand, (C) shows the state where the joint has reached the first stand, (D) shows the state where the thickness changing position S1 has reached the second stand, (E) shows the state where the thickness changing position S2 has reached the second stand, and (F) shows the state where the joint has reached the second stand. [Diagram 3] 1 is a graph showing a change in tension between a first stand and a second stand in a conventional method for changing a flying strip gauge. [Figure 4]FIG. 1 is an explanatory diagram showing a method for changing plate thickness while traveling in accordance with a first embodiment, in which (A) shows a state in which the plate thickness changing position is upstream of the first stand, (B) shows a state in which the plate thickness changing position has reached the first stand, (C) shows a state in which the joint has reached the first stand, (D) shows a state in which the plate thickness changing position has reached the second stand, and (E) shows a state in which the joint has reached the second stand. [Diagram 5] 4 is a graph showing a change in tension between a first stand and a second stand in the method for varying a flying strip thickness according to the first embodiment. [Figure 6] FIG. 4 is a schematic diagram showing a cold rolling facility in a second embodiment of the present invention. [Figure 7] FIG. 11 is an explanatory diagram showing a method for changing thickness while traveling in a second embodiment of the present invention, where (A) shows a state where the thickness changing position is upstream of the first stand, (B) shows a state where the thickness changing position has reached the first stand, (C) shows a state where the joint has reached the first stand, (D) shows a state where the joint has passed the first stand and the thickness changing position is upstream of the second stand, (E) shows a state where the thickness changing position has reached the second stand, and (F) shows a state where the joint has reached the second stand. [Figure 8] 6 is a flowchart showing a method for changing a running gauge in a second embodiment of the present invention. [Figure 9] 1 is a graph showing inter-stand tension changes between a first stand and a second stand in a case where the end of running gauge change is early. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the following detailed description, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, identical or similar parts are given identical or similar symbols, and duplicated explanations are omitted. Each drawing is schematic and may differ from the actual one. In addition, the embodiments shown below are examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, structures, arrangements, etc. of the components as described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims described in the claims.

[0014] First Embodiment (Configuration of a tandem cold rolling mill) First, a running gauge method according to a first embodiment of the present invention will be described. Fig. 1 is a schematic diagram showing an example of a continuous cold rolling facility 1 in the first embodiment of the present invention. Note that Fig. 1 does not show other devices associated with the facility (for example, an unwinder, a welder, and a looper on the entry side, and a cutter, a winder, and other devices on the exit side).

[0015] As shown in FIG. 1, the continuous cold rolling equipment 1 includes a tandem rolling mill 2, a plurality of plate thickness measuring devices 3, a rolling control controller (PLC) 4 that controls the tandem rolling mill 2, and a control computer (process computer) 5 that manages the continuous cold rolling equipment including the rolling control controller 4.

[0016] The tandem rolling mill 2 is a continuous cold tandem rolling mill having, in order from the entry side in the sheet passing direction, a first stand 2A to a fifth stand 2E.

[0017] Each of the first stand 2A to the fifth stand 2E is equipped with a work roll 21, a roll speed control device 22 which is an electric motor that changes the roll speed of the work roll 21, and a roll gap control device 23 which changes the roll gap between the upper and lower work rolls 21.

[0018] The multiple thickness measuring devices 3 are provided between adjacent stands (between stands) of the first stand 2A to the fifth stand 2E, and continuously measure the thickness of the rolled material 6, which is a metal plate passing between the stands. There is no particular limitation on the method of measuring the thickness using the thickness measuring devices 3, but for example, a measuring device that irradiates the object with gamma rays or X-rays, measures the attenuation of the gamma rays (X-rays) that pass through the object, and converts it into thickness is considered. The results of the thickness measurements by the thickness measuring devices 3 are transmitted to the control computer 5.

[0019] The control computer 5 sets the roll gap value, roll gap change amount, roll speed, roll speed change amount, etc. of each stand. Then, the rolling controller 4 executes calculations and processing online to control the roll speed control device 22 of each stand of the first stand 2A to the fifth stand 2E and the roll gap control device 23 of each stand, based on each value acquired from the control computer 5.

[0020] In such cold rolling equipment 1, the tail end of the preceding material 61 and the leading end of the following material 62 are joined at a joint W by a welding machine (not shown) disposed on the entry side of the tandem rolling mill 2, for example by welding. The material 6 to be rolled is then rolled to a predetermined finished thickness by being rolled successively from the first stand 2A to the final stand, the fifth stand 2E, of the cold rolling mill. Thereafter, the material 6 is cut by a flying cut-off machine at or near the joint W between the preceding material 61 and the following material 62, and the cut following material 52 is taken up by a tension reel separate from that of the preceding material 51.

[0021] Here, if the rolling conditions such as the base plate thickness, finished plate thickness, deformation resistance, etc. are different between the preceding material 61 and the following material 62, when the preceding material 61 and the following material 62 are continuously rolled by the cold rolling mill, the rolling conditions are changed while the material is in flight (i.e., while the material to be rolled 6 is being transported within the tandem rolling mill 2), and a thickness change while the material is in flight is performed.

[0022] In a typical conventional method, the roll gap setting value is changed at the timing when the thickness change position, which is set a predetermined distance away from the joint on the side of the preceding material 61, reaches the stand based on tracking of the joint W (using the joint W as a reference). Specifically, the thickness change while traveling is performed by the method shown in Figures 2(A) to 2(F). The tension fluctuation between the first stand 2A and the second stand 2B at this time is shown in Figure 3. The timings (a) to (f) in Figure 3 correspond to the timings in the states of Figures 2(A) to (F), respectively.

[0023] First, as shown in Fig. 2(A), rolling is performed with the roll gap value of each stand set to that for the preceding material 61. In Fig. 2(A), the position indicated by S1 on the tail end side of the preceding material 61 is the position where the roll gap setting value in the first stand 2A is changed.

[0024] As rolling continues, as shown in Fig. 2(B), the thickness changing position S1 of the preceding material 61 reaches the first stand 2A, and the roll gap setting value of the first stand 2A starts to be changed so that the roll gap setting value of the first stand 2A becomes that for the following material 62. The thickness changing position S1 is set at a position a predetermined distance away from the joint W on the tail end side of the preceding material 61. The position of the thickness changing position S1 is set depending on the time required to change the roll gap, the sheet passing speed, etc., as will be described later.

[0025] As rolling progresses further, as shown in Fig. 2(C), the change in the roll gap setting value of the first stand 2A is completed, and the first stand 2A starts rolling the following material 62. Usually, the thickness changing position S1 is set so that the change in the roll gap setting value is completed before the joint W reaches the first stand 2A. Then, by changing the roll gap setting value as shown in Fig. 2(B) and Fig. 2(C), the thickness changes in a tapered shape from the tail end of the preceding material 61 to the joint W.

[0026] As the rolling proceeds further, as shown in FIG. 2(D), the thickness change position S1 in the first stand 2A reaches the second stand 2B. As described later, the change in the roll gap setting value in the second stand 2B starts when the thickness change position S2 reaches the second stand 2B. The thickness change position S2 is set at a position a predetermined distance away from the joint W on the tail end side of the preceding material 61, similar to the thickness change position S1. Note that, as shown in FIG. 2(D), since the preceding material 61 that has passed the first stand 2A has been rolled and its length in the longitudinal direction has been extended, the thickness change position S1 in the first stand 2A and the thickness change position S2 in the second stand 2B are in different positions.

[0027] In the state shown in Fig. 2(D), the tapered thickness portion of the rolled material 6 reaches the second stand 2B before the roll gap of the second stand 2B is changed. At this time, the roll gap setting value of the second stand 2B is set for the preceding material 61, so the tension between the first stand 2A and the second stand 2B decreases as shown in Fig. 3. This causes a large tension fluctuation and increases the risk of breakage.

[0028] As rolling progresses further, as shown in Figure 2 (E), the plate thickness change position S2 reaches the second stand 2B, and the roll gap setting value of the second stand 2B begins to be changed so that the roll gap setting value of the second stand 2B becomes that for the following material 62.

[0029] Furthermore, as shown in FIG. 2(F), the change in the roll gap setting value of the second stand 2B is completed, and the second stand 2B starts rolling the following material 62. As for the third stand 2C and onwards, the roll gap setting value is changed in the same manner as the second stand 2B, thereby changing the running thickness. That is, in each stand from the third stand 2C onwards, the roll gap setting value is changed as the thickness change position S that is set for each stand passes through each stand. In each stand, the setting of the roll peripheral speed is changed in synchronization with this change in the roll gap setting.

[0030] (How to change the running thickness) Figures 4(A) to 4(E) are explanatory diagrams showing a method for changing the running strip thickness according to the first embodiment. Figures 4(A) to 4(C) show a change in the roll gap set value of the first stand 2A, and the roll gap set value is changed in the same manner as in Figures 2(A) to 2(C). Figure 5 shows the tension fluctuation between the first stand 2A and the second stand 2B at this time. The timings (a) to (e) in Figure 5 correspond to the timings in the states of Figures 4(A) to (E), respectively.

[0031] In the first embodiment, a thickness measuring device 3 is provided between the first stand 2A and the second stand 2B, and the thickness of the rolled material 6 passing between the stands is continuously measured. The control computer 5 detects a thickness change position S at which the thickness of the rolled material 6 changes, based on the measurement results of the thickness measuring device 3. The detected thickness change position S is the thickness change position S set in the first stand 2A, and is the position at which the thickness changes in a tapered shape.

[0032] Next, when the thickness change position S is detected between the first stand 2A and the second stand 2B, the control computer 5 changes the roll gap set value of the second stand 2B at the timing when the thickness change position S reaches the second stand 2B, as shown in Fig. 4(D). At this time, the roll gap set value of the second stand 2B is changed from the set value for the preceding material 61 to the set value for the following material 62. Since the roll gap set value of the second stand 2B is changed at the thickness change position S, as shown in Fig. 5, even if the tapered thickness portion reaches the second stand 2B, the reduction in tension is compensated, and the risk of breakage due to the reduction in tension can be reduced.

[0033] As the rolling progresses, as shown in FIG. 4(E), the change in the roll gap setting value of the second stand 2B is completed, and the second stand 2B starts rolling the following material 62. As for the third stand 2C and onwards, the roll gap setting value is changed in the same manner as the second stand 2B, thereby changing the running thickness. That is, in each stand after the third stand 2C, the thickness change position S is detected from the measurement result of the thickness measuring device 3 provided between each stand, and the roll gap setting value is changed when the thickness change position S reaches each stand. In each stand, the setting of the roll peripheral speed is changed in synchronization with this change in the roll gap setting.

[0034] In the first embodiment, the material 6 to be rolled is a metal plate, and is preferably a steel plate, particularly a high deformation resistance steel plate. The high deformation resistance steel plate is, for example, a steel plate of electromagnetic material or high tensile material. Such high deformation resistance steel plate has a large amount of reduction change during thickness change while flying, and the thickness of the front part of the welded part due to the thickness change while flying at the front stand is largely separated from the set thickness, resulting in large tension fluctuation. For this reason, by applying the method for changing the thickness while flying according to the first embodiment, troubles such as breakage can be prevented, and stable production can be performed.

[0035] The method for changing the thickness of a running material according to the first embodiment is a method for changing the thickness of a running material when a tandem rolling mill 2 is used to continuously roll a material to be rolled 6, which is a metal plate consisting of a leading material 61 and a trailing material 62 joined together. The method continuously measures the thickness of the material to be rolled between target stands, detects a thickness change position S in the vicinity of a joint W, and changes the roll gap of the target stand when the thickness change position reaches the target stand. The target stand is a rolling stand that performs the thickness change, and the preceding stand is a rolling stand that is installed adjacent to the target stand on the upstream side in the rolling direction. For example, in FIG. 4, when changing the roll gap of the second stand 2B, the second stand 2B is the target stand and the first stand 2A is the preceding stand.

[0036] According to the method for varying the thickness on the fly in accordance with the first embodiment, it is possible to shorten the thickness off-gage length, since there is no need to provide an intermediate thickness, compared to the method in Patent Document 1. Furthermore, according to the method for varying the thickness on the fly in accordance with the first embodiment, the roll gap is changed using the thickness change point in the front stand as the thickness change point in the rear stand, so that tension fluctuations can be suppressed regardless of the material or specifications of the rolled material 6.

[0037] <Second embodiment> (Configuration of a tandem cold rolling mill) Next, a method for measuring thickness while traveling according to a second embodiment of the present invention will be described. Fig. 6 is a schematic diagram showing an example of a continuous cold rolling facility 1 according to the second embodiment of the present invention. In Fig. 6, similar to Fig. 1, other devices associated with the facility are not shown.

[0038] As shown in FIG. 6, the continuous cold rolling equipment 1 includes a tandem rolling mill 2, a programmable logic controller (PLC) 4 that controls the tandem rolling mill 2, a control computer (process computer) 5 that manages the continuous cold rolling equipment including the rolling controller 4, and a plurality of strip speed meters 7.

[0039] The tandem rolling mill 2 is a continuous cold tandem rolling mill having, in order from the entry side in the sheet passing direction, a first stand 2A to a fifth stand 2E.

[0040] Each of the first stand 2A to the fifth stand 2E is equipped with a work roll 21, a roll speed control device 22 which is an electric motor that changes the roll speed of the work roll 21, and a roll gap control device 23 which changes the roll gap between the upper and lower work rolls 21.

[0041] The control computer 5 sets the roll gap value, roll gap change amount, roll speed, roll speed change amount, etc. of each stand. Then, the rolling controller 4 executes calculations and processing online to control the roll speed control device 22 of each stand of the first stand 2A to the fifth stand 2E and the roll gap control device 23 of each stand, based on each value acquired from the control computer 5.

[0042] The strip speed meters 7 are provided between adjacent stands (between stands) of the first stand 2A to the fifth stand 2E, and continuously measure the strip speed, which is the speed in the transport direction of the rolled material 6, which is a metal sheet, passing between the stands. There is no particular limitation on the method of measuring the strip speed using the strip speed meters 7, but a laser Doppler velocimeter, for example, is conceivable. The results of measurement of the strip speed by the strip speed meters 7 are transmitted to the control computer 5.

[0043] As in the first embodiment, in the cold rolling facility 1, the tail end of the preceding strip 61 and the leading end of the following strip 62 are joined at a joint W by a welding machine (not shown) disposed on the inlet side of the tandem rolling mill 2, for example by welding. Next, the rolled strip 6 is rolled to a predetermined finish thickness by being rolled in sequence from the first stand 2A to the final stand, the fifth stand 2E, of the cold rolling mill. Thereafter, the strip is cut by a flying cut-off machine at or near the joint W between the preceding strip 61 and the following strip 62, and the cut following strip 52 is wound up by a tension reel separate from that of the preceding strip 51. Then, as in the first embodiment, when the rolling conditions, such as the mother strip thickness, the finish strip thickness, and the deformation resistance, are different between the preceding strip 61 and the following strip 62, a flying thickness change is performed.

[0044] (How to change the running thickness) Figures 7(A) to 7(F) and 8 are explanatory diagrams showing a method for changing the running strip thickness according to the second embodiment. Figures 7(A) to 7(C) show a method for changing the roll gap set value of the first stand 2A (a method for changing the running strip thickness), and the roll gap set value is changed in the same manner as in Figures 2(A) to 2(C).

[0045] In the following, a method for changing the roll gap setting value of the second stand 2B, that is, a method for changing the flying strip thickness, will be described. The flying strip thickness change of the second stand 2B is performed according to the process flow shown in FIG. 8. Note that the flying strip thickness change of the rolling stands after the second stand 2B is performed in the same manner as the second stand 2B. Here, as in the first embodiment, the rolling stand that performs the flying strip thickness change is also called the target stand, and the rolling stand preceding the target stand is also called the preceding stand. Also, the process flow shown in FIG. 8 is started when the flying strip thickness change of the preceding stand (first stand 2A) starts, that is, when the state of FIG. 7(B) is reached.

[0046] When the thickness change on the fly at the first stand 2A starts, first, the strip speed meter 7 provided between the target stands is used to continuously measure the strip speed of the rolled material 6 passing between the target stands (S100). The target stands mean the area between the target stand and the preceding stand, and in the case where the target stand is the second stand 2B, it is the area between the second stand 2B and the first stand 2A. Furthermore, the strip speed is continuously measured at least until the thickness change on the fly at the target stand is performed. In other words, in the case where the target stand is the second stand 2B, the strip speed is continuously measured at least from the time when the thickness change position S shown in FIG. 7(B) arrives at the first stand 2A until the thickness change position S shown in FIG. 7(E) arrives at the second stand 2B. Furthermore, the control computer 5 tracks the thickness change position S of the rolled material 6 based on the measurement result of the strip speed between the target stands by the strip speed meter 7.

[0047] After step S100, the control computer 5 determines the length L of the tapered plate thickness portion after rolling in the front stand. N-1is calculated (S102). Here, N indicates the number of the target stand (Nth stand). That is, when the target stand is the second stand 2B, the length L1 of the tapered thickness portion after rolling in the first stand 2A is calculated. The tapered thickness portion is a portion where the thickness of the rolled material 6 changes in a tapered shape due to a running thickness change in the preceding stand. When the target stand is the second stand 2B, the tapered thickness portion is the portion from the thickness change position S to the joint W in FIG. 7(D).

[0048] Length of tapered plate thickness L N-1 is calculated by integrating (the strip speed of the front stand) × (time) until the thickness change while traveling at the front stand is completed. Specifically, the length L of the tapered strip thickness N-1 is calculated using the following formula (1). In formula (1), the measurement timing of the strip speed is the time step, and the strip speed v N-1(i) and time T i From the length L N-1 The number of time steps is 1 at the start of the measurement of the thickness change while on the run, and m at the end of the measurement of the thickness change while on the run. i indicates the elapsed time from a predetermined timing as a starting point to each time step.

[0049]

number

[0050] After step S102, the control computer 5 determines the time t until the tapered plate thickness portion enters the target stand. N In step S104, the strip speed between the target stands measured by the strip speed meter 7 immediately before the running strip thickness change is performed in the target stand, that is, immediately before step S104, and the length L calculated in step S102 are calculated.N-1 and time t N In the second embodiment, the time t N corresponds to the time from when the thickness changing position S of the rolled material 6 enters the target stand to when the joint W enters the target stand. Time t N can be calculated using the following formula (2).

[0051]

number

[0052] After step S104, the control computer 5 calculates the change amount ΔS of the rolling position in the target stand. N and time t N and the change speed of the pressing position R N is calculated (S106). The change amount of the reduction position in the target stand corresponds to the adjustment amount of the roll gap in the target stand, and is the movement amount of the upper and lower work rolls 21 in the thickness direction of the material 6 to be rolled due to the change in plate thickness. The change amount of plate thickness is a value that is set in advance. The change speed R of the reduction position in the target stand N is the moving speed of each work roll 21 when changing the rolling position (i.e., when changing the running thickness). N can be calculated using the following formula (3). The processes up to step S104 are performed before the thickness changing position S reaches the target stand. It is preferable that the processes of steps S102 and S104 are performed immediately before the tapered thickness portion reaches the target stand.

[0053]

number

[0054] After step S106, when the plate thickness change position S reaches the target stand, the control computer 5 changes the thickness change speed R calculated in step S106. N and thickness change amount Δs NThe running thickness is changed, that is, the roll gap setting value is changed (S108). As described above, the thickness change position S is tracked based on the measurement result of the strip speed, and the control computer 5 changes the running thickness by detecting the arrival of the thickness change position S at the target stand based on the tracking result. In step S108, the running thickness is changed at the change speed R N and thickness change amount Δs N The flying thickness change is completed when the welded portion W reaches the target stand. When the target stand is the second stand 2A, as shown in FIG. 7(D), the arrival of the thickness change position S at the second stand 2A is detected by tracking, and the roll gap setting value at the second stand 2B is changed. Then, in step S108, the change speed R N and thickness change amount Δs N By performing the flying thickness change at step 4, the flying thickness change ends at the timing when the welded portion W reaches the second stand 2B, as shown in FIG. 7(F).

[0055] As described above, the flying strip thickness is changed in the third stand 2C to the fifth stand 2E in the same manner as in the second stand 2B. In this case, the strip thickness change position S can be tracked in the line of the tandem rolling mill 2 by using the results of measuring the strip speed between a plurality of target stands from the first stand 2A.

[0056] In the second embodiment, the material 6 to be rolled is a metal plate, and is preferably a steel plate, particularly a high deformation resistance steel plate. The high deformation resistance steel plate is, for example, a steel plate of electromagnetic material or high tensile material. Such high deformation resistance steel plate has a large amount of roll reduction change during thickness change while flying, and the thickness of the front part of the welded part due to the thickness change while flying at the front stand is largely separated from the set thickness, resulting in large tension fluctuation. For this reason, by applying the method for changing the thickness while flying according to the second embodiment, troubles such as breakage can be prevented and stable production can be performed.

[0057] The method for changing the thickness while traveling in the second embodiment is a method for changing the thickness while traveling when a rolled material 6 consisting of a leading material 61 and a trailing material 62 which are metal plates joined is continuously rolled by a tandem rolling mill 2, in which the plate speed of the rolled material is continuously measured between the target stands, the plate thickness change position S near the joint W is tracked, and the roll gap of the target stand is changed at the timing when the plate thickness change position reaches the target stand.

[0058] According to this method, as in the first embodiment, it is not necessary to provide an intermediate thickness, and therefore the thickness off-gauge length can be shortened. Also, according to the method for changing the thickness while running according to the second embodiment, the thickness change point in the front stand is used as the thickness change point in the rear stand to change the roll gap, so tension fluctuations can be suppressed regardless of the material or specifications of the rolled material 6.

[0059] In addition, the method for changing the thickness while rolling according to the second embodiment uses the plate speed measured between the target stands to calculate the length L of the tapered plate thickness portion after rolling in the front stand. N-1 Calculate the length of the tapered plate thickness L N-1 The rate of change in the roll position R is calculated by dividing by the amount of change in the roll position in the target stand. N Calculate the change speed R N to change the roll gap of the target stand.

[0060] Here, FIG. 9 shows tension changes between the first stand 2A and the second stand 2B in the case where the flying thickness change is completed in the middle of the tapered thickness part in the second stand 2B, that is, the end of the flying thickness change is earlier than that in the second embodiment. If the flying thickness change is completed too early, as shown in the vicinity of the timing of (f) in FIG. 9, the change of the roll gap ends in the middle of the tapered thickness part, and the tension may become excessive in the subsequent rolling of the tapered thickness part. However, according to the flying thickness change method of the second embodiment, the timings at which the start point (thickness change position S in FIG. 7) and the end point (joint W in FIG. 7) of the tapered thickness part pass through the target stand can be set as the start and end timings of the change of the roll gap. As a result, according to the flying thickness change method of the second embodiment, it is possible to suppress the tension from becoming excessive.

[0061] The thickness in the first embodiment and the speed in the second embodiment are collectively referred to as operation data. In other words, the method for changing the thickness while running according to the present invention detects or tracks the thickness change position S from the operation data of the rolled material 6 measured between the target stands, and changes the thickness while running at the timing when the thickness change position S reaches the target stand.

[0062] <Modification> Although the present invention has been described above with reference to specific embodiments, it is not intended that the invention be limited by these descriptions. By referring to the description of the present invention, other embodiments of the present invention including various modifications in addition to the disclosed embodiments will be apparent to those skilled in the art. Therefore, it should be understood that the embodiments of the invention described in the claims also include embodiments including these modifications described herein, either alone or in combination.

[0063] For example, in the first and second embodiments, the tandem rolling mill 2 shown in Fig. 1 is a rolling mill having five stands, but the present invention is not limited to such an example. The number of stands of the tandem rolling mill 2 may be two or more, and may be six or more. In the case of a general tandem rolling mill 2, the upper limit of the number of stands is six.

[0064] In the first and second embodiments, the case where the thickness of the following material 62 in the rolled material 6 is thinner than the thickness of the preceding material 61 has been described, but the present invention is not limited to such an example. The rolled material 6 may be such that the thickness of the following material 62 is thicker than the thickness of the preceding material 61. In this case, the tension between the stands fluctuates to become larger.

[0065] Furthermore, in the first and second embodiments, four thickness measuring devices 3 or strip speed meters 7 are provided, and the roll gap set values ​​at the second stand 2B to the fifth stand 2E are changed based on the measurement results of the four thickness measuring devices 3 or strip speed meters 7, but the present invention is not limited to such an example. For example, the roll gap set value may be changed only between stands where tension fluctuations are a large problem, as in the above embodiment, and the roll gap set value may be changed between other stands by a control method similar to that of the conventional method. In this case, the thickness measuring device 3 or strip speed meter 7 may be provided only between necessary stands. Furthermore, the thickness measuring device 3 and strip speed meter 7 may be provided between different stands, and the running thickness change corresponding to the first embodiment or the second embodiment may be performed for each target stand according to the thickness measuring device 3 or strip speed meter 7 provided between the stands.

[0066] Furthermore, in the second embodiment, the strip speed meter 7 is used as a method for measuring the strip speed, but the present invention is not limited to this example. For example, the strip speed may be calculated by calculating the motor rotation speed of each rolling stand measured by a PLG or an Absolute Coder and the forward slip calculated from operational data. In consideration of measurement accuracy, it is preferable to measure the strip speed using the strip speed meter 7. [Explanation of symbols]

[0067] 1. Cold rolling mill equipment 2 Tandem rolling mill 2A~2E 1st stand~5th stand 21 Work roll 22 Roll speed control device 23 Rolling control device 3 Plate thickness measuring device 4. Rolling controller 5 Control computer 6 Rolled material 61 Preceding material 62 Trailing material 7 Board speedometer

Claims

1. A method for changing a thickness of a rolling material in a continuous rolling process using a tandem rolling mill, the method comprising the steps of: The plate speed of the rolled material is continuously measured between a target stand which is a rolling stand performing plate thickness change and a front stand which is a rolling stand in front of the target stand, The thickness change position where the thickness change is started in the front stand near the joint between the preceding material and the following material is tracked from the measurement result of the plate speed, Calculate the length of the tapered plate thickness portion after rolling in the front-stage stand using the plate speed measured between the target stands; The time t N is calculated by dividing the length of the tapered plate thickness portion by the plate speed; calculating a change speed of the roll position from the change amount ΔS N of the roll position in the target stand and the time t N ; A method for changing a thickness while running, the method comprising: changing a roll gap of the target stand at the calculated change speed at a timing when the thickness change position reaches the target stand.

2. The method for varying a thickness of a rolling material according to claim 1, wherein the rolling material is a steel plate of an electromagnetic material or a high tensile material.

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