Control and setting method of plate wedges in hot reversible plate rolling

Abstract

To provide a controlling and setting method for acquiring a plate having a zero or small value of a plate wedge which is a plate width end plate thickness difference between a working side and a driving side over the entire length in reversible hot rolling of a plate material.SOLUTION: Regarding reversible rolling such as hot rough rolling or thick plate rolling, a rolling direction plate thickness meter, a mill setting calculator, a plate wedge control setter, and a roll gap leveling device are provided at multiple points in a plate thickness direction on an outlet side. A plate wedge is measured on the outlet side to calculate a plate wedge ratio. This ratio is set as an inlet side plate wedge ratio of a next path, and an outlet side plate wedge target value is determined in such a manner that a difference from the outlet side plate wedge ratio is within upper and lower limit values determined by experiment or the like. In a next path, the outlet side plate wedge ratio of the last path is set as the inlet side plate wedge ratio, and an outlet side plate wedge target value is similarly determined to be achieved. In subsequent paths, plate wedges are similarly controlled and set.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for controlling and setting a plate wedge in hot plate rolling of metals and the like, particularly in rough rolling of a hot strip mill or single-stand reversible rolling such as a heavy plate rolling mill.

Background Art

[0002] Conventionally, in hot plate rolling of metals and the like, it has been desired to eliminate the wedge of the plate to be rolled, that is, to make the plate thickness difference between the working side and the driving side in the plate width direction zero. If there is a wedge in the plate to be rolled, the dimensions and flatness of the plate to be rolled become poor, the tip and tail of the material to be rolled are curved, or a so-called camber occurs, and the entire plate is curved in a C shape in the length direction. These cambers and curved portions need to be cut off, which has reduced the yield of the product plate. In addition, the snaking and narrowing of the plate have hindered normal rolling. As a countermeasure against these problems, in Patent Document 1, a typical example of the finishing mill of a hot strip mill is a 7-stand tandem rolling mill. A rolling direction thickness gauge at multiple points in the plate width direction is installed on the outlet side of the final stand to measure the wedge of the material to be rolled, and the deviation from the desired value of the wedge (usually zero) is feedback-controlled to the roll gap leveling from the first stand to the final seventh stand to make the wedge of the material to be rolled the desired value over the entire length of the plate. This patent has already been put into practical use and has achieved great effects in the actual finishing mill of a hot strip mill. In addition, the formulas and the like applied in this patent have been confirmed to be correct in actual machines. By the way, in the roughing mill of a hot strip mill or a heavy plate rolling mill, the normal equipment repeats reversible rolling with one stand of an edger and a horizontal mill (hereinafter referred to as a single stand), so the method of Patent Document 1 has the drawback that it cannot be directly applied. Hereinafter, the material to be rolled may be simply referred to as a plate, but the two are the same. Also, unless otherwise specified, the outlet plate thickness is the one at the center of the plate width. As another example, in Non-Patent Document 1, in a single-stand rolling mill in which an edger and a horizontal rolling mill are usually integrated in heavy plate rolling, reversible rolling is performed to obtain a desired heavy plate product. In this case, the camber (curvature) of the plate was also an issue. In response, a plurality of plate width off-center gauges are installed in the rolling direction on the exit side of the single-stand rolling mill to measure the off-center of the center of the plate width in the length direction, determine the camber of the plate, and based on this, determine the wedge correction amount of the plate and control the necessary roll gap leveling to reduce the camber of the plate, as reported. In addition, Non-Patent Document 2 shows a method of calculating the deformation of a rolling mill, rolls, and a plate as a system of simultaneous equations. Furthermore, Non-Patent Document 3 describes that there is metal flow in the plate width direction in plate rolling, which relaxes the flatness of the plate. However, although the relationship between plate crown and flatness is described, the relationship between plate wedge and plate flatness, etc. is not described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the reversible rolling of a conventional hot strip mill's roughing mill, plate mill, etc., the plate wedge, which is the plate thickness difference between the working side plate width end and the drive side plate width end shown in Fig. 1, is the cause of the flatness and camber of the plate, further the cause of the widthwise bending at the tip and tail ends of the plate, also the cause of the narrowing due to single waves or plate snake-like movement, and furthermore, there has been a problem such as deteriorating the dimensional accuracy of the product.

Means for Solving the Problem

[0006] The method for controlling and setting the plate wedge in plate rolling according to this invention is in the case of reversibly rolling a plate material by a roughing mill for hot rolling or a plate mill as shown in Fig. 2. In a rolling facility equipped with a multi-point thickness gauge (hereinafter referred to as a multi-point thickness meter) that measures the plate thickness at multiple points in the plate width direction (at least the plate thickness at the plate width end on the working side, the plate thickness at the center of the plate width, and the plate thickness at the plate width end on the drive side) in the rolling direction on the exit side of the rolling mill, and a computer for setting calculation of rolling. The setting calculation of rolling is to predict and calculate the plate thickness, plate width, rolling load, roll gap at the center of the plate width, rolling speed, etc. for each pass before rolling, which is a well-known technique already used in many rolling mills. Further, it is equipped with, for example, a programmable logic controller (hereinafter referred to as PLC) for controlling the rolling mill. In rolling, the slab as the material is rolled to the product plate thickness, but some multi-point thickness meters cannot measure above a certain reference plate thickness (for example, 100 mm). Therefore, the measurement of the plate wedge is the measurement when the plate thickness is below the reference plate thickness. First, in the odd-numbered passes (rolling in the direction of the multi-point thickness meter), when the plate thickness reaches below the reference plate thickness, measure the plate thickness at the plate width end on the working side and the plate width end on the drive side, and obtain the plate wedge, which is the difference between these. Then obtain the plate wedge deviation, which is the difference from the desired plate wedge value (actually, it is a zero value). Also measure the plate thickness at the center of the plate width. Hereinafter, since the plate wedge deviation is substantially the plate wedge value, it is referred to as the plate wedge value. And from the subsequent passes to the final pass, one of the features of this patent is to gradually reduce the plate wedge value at the exit side of each pass and finally make it zero. An example is shown in Fig. 5. Incidentally, in the process of gradually reducing the plate wedge value for each pass and finally making it zero, it is important to ensure that the elongation rate difference and flatness between the working side and the driving side of the plate do not deteriorate in each pass, that the plate does not snake or become pinched, and that there is no camber. The relationship between the plate crown and flatness is described in Non-Patent Document 3. On the other hand, there is no description about the plate wedge. Incidentally, if the difference in the plate wedge ratio (plate wedge / plate thickness) between the inlet side and the outlet side in an arbitrary pass is within a certain range between the upper limit value and the lower limit value, it has been invented that the elongation rate difference between the working side and the driving side of the plate is within the allowable value, the plate flatness does not deteriorate, the plate does not snake or become pinched, and no camber occurs. Incidentally, in plate rolling, the metal flow in the plate width direction of the plate is known, and this alleviates the deterioration of the plate flatness, the snaking and pinching of the plate, and the occurrence of camber. Considering these factors, the upper limit value and the lower limit value of the difference in the plate wedge ratio between the inlet side and the outlet side of an arbitrary pass can be experimentally measured and organized into an empirical formula or experimental values. Hereinafter, these will be referred to as the plate wedge ratio difference limit formula. Therefore, when the reference plate thickness is reached, the plate wedge and the plate thickness at the center of the plate width are measured, and if the control settings are adjusted so that the plate wedge ratio difference is within the plate wedge ratio difference limit formula in subsequent passes and rolling is performed, the flatness will not deteriorate, the plate will not snake or become pinched, and no camber will occur, and the plate wedge can be made zero over the entire length up to the final pass. This is another feature of this patent. Next, when using the plate wedge ratio difference limit formula, the plate wedge on the outlet side can be measured after the i-th pass when the plate thickness reaches the reference plate thickness as described above. Dividing this by the measured value of the outlet side plate thickness gives the plate wedge ratio on the inlet side in the next (i + 1)-th pass. Therefore, the minimum plate wedge ratio on the outlet side that falls within the plate wedge ratio difference limit in the next (i + 1)-th pass can be obtained. Multiplying this value by the calculated outlet side plate thickness in the setting gives the target value of the plate wedge after plate wedge control on the outlet side in the (i + 1)-th pass. The above is another feature of this patent. Next, in the (i + 2)-th pass, the target value / thickness of the exit-side plate wedge in the aforementioned (i + 1)-th pass becomes the entrance-side plate wedge ratio. By applying the plate wedge ratio difference limit formula to the (i + 2)-th pass again, the target value of the plate wedge after plate wedge control on the exit side can be obtained. By performing such calculations up to the final pass, the target values of the plate wedge after plate wedge control can be determined for the exit sides of all passes. FIG. 5 is an example of this. This is another feature of this patent. Incidentally, it has been invented that the target value of the exit-side plate wedge for an arbitrary pass is the sum of the roll gap leveling correction amount for that pass multiplied by the influence coefficient and the entrance-side plate wedge for that pass multiplied by the inheritance coefficient. Hereinafter, this relational expression will be referred to as the leveling, influence coefficient, and inheritance coefficient formula. These influence coefficients and inheritance coefficients can be calculated for all steel grades, plate thicknesses, and plate widths by simultaneously considering the deformation of the rolling mill, the deformation of the rolls, and the deformation of the plate. This calculation is quite extensive and can be performed online, but in practice, it is considered better to calculate it offline due to economic factors and formulate the results. (See, for example, Non-Patent Document 2)

[0007] Using the above results, the wedge of the plate is measured at a plate thickness below the reference plate thickness, and the target value of the exit-side plate wedge is obtained using the plate wedge ratio difference limit formula in the subsequent passes. To achieve this, the roll gap leveling control amounts up to the final pass are obtained in order using the leveling, influence coefficient, and inheritance coefficient formula and applied before rolling for each pass, thereby obtaining a product having a target (zero) plate wedge over the entire length of the plate. This is another feature of this patent. In addition, an experiment of changing the roll gap leveling stepwise during rolling was conducted at an arbitrary stand of a 7-stand continuous hot finishing rolling mill, and the influence coefficient and inheritance coefficient were identified to improve the accuracy, and good results were obtained. This can also be implemented on a reversible rolling mill. Also, for the next material to be rolled, the roll gap leveling correction amount in the final pass of the previous material is learned and set. There are various learning methods such as the exponential smoothing method, the AI method, and the first-order lag system.

Advantages of the Invention

[0008] According to the present invention, over the entire length of the plate, there are no cambers or curvatures at the leading and trailing ends of the plate, there is no pinching due to the meandering of the plate during rolling, the flatness of the plate is not deteriorated, and a product with a desired plate thickness and plate width can be obtained over the entire length of the plate.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a control and setting method for a plate wedge in hot reversible plate rolling will be described. As a typical example, single - stand reversible rolling in a hot strip mill roughing for hot - rolling a slab or single - stand reversible rolling in heavy plate rolling will be described.

Examples

[0011] FIG. 1 is a diagram for explaining the shape of a plate wedge. A plate wedge is the plate thickness difference between the working - side plate width end and the drive - side plate width end in the plate width direction. The plate thickness end is defined, for example, at positions 40 (mm), 100 (mm) from the plate edge, that is, [Number] TIFF0007685721000002.tif This is the plate thickness at the end of the 6155 plate width. Generally, it is desired to set the plate wedge to zero over the entire length of the plate. Therefore, originally, the plate wedge deviation is obtained by subtracting the plate wedge target value from equation (1). TIFF0007685721000003.tif We will call this the deviation.

[0012] Next, FIG. 2 is a system configuration diagram conceptually showing an overall configuration example of the method for controlling and setting the plate wedge according to the present invention. The material to be rolled 11 is a slab heated before rolling. As a typical example, the plate thickness is 200 to 300 (mm), etc. This is reversely rolled by a reversible rolling mill composed of an edger 6 and a horizontal mill 7. In the rough rolling of a hot strip mill, it is reversely rolled to a plate thickness of about 30 to 50 (mm). In heavy plate rolling, it is rolled to a plate thickness of about 5 to 6 (mm), and a typical example of the product plate width is 5000 (mm), etc. The rolling in the direction of the multi-point thickness gauge 8 from the reversible rolling mills 6 and 7 is set as 5 odd passes, and the reverse direction is set as 4 even passes. The multi-point thickness gauge 8 continuously measures the plate thickness in the rolling direction at at least three points: the drive-side plate width end, the plate width center, and the work-side plate width end. Usually, in the multi-point thickness gauge 8, X-rays or γ-rays are passed through the material to be rolled to measure the plate thickness. However, many can measure accurately below a certain reference plate thickness. 14 is a rolling order. This inputs the steel type, plate thickness, plate width, weight, product plate thickness, product plate width, etc. of the material slab to be rolled into the mill setting computer 13. Mill setting calculation is a well-known and established technology. Also, the slab temperature (not shown) is separately input into the mill setting calculation of 13. In the mill setting calculation of 13, before rolling, the number of rolling passes, the outgoing-side plate thickness, plate width, rolling load, rolling speed, roll gap, etc. are predicted and calculated. Also, through learning described later, the roll gap leveling amount is calculated and set.

[0013] In the wedge control setting method for the material to be rolled according to the present invention, when the material to be rolled has become thinner to the reference plate thickness measurable by the multi-point thickness gauge, starting from the time when 11 materials to be rolled reach 8 multi-point thickness gauges in 5 odd-numbered passes, the plate thicknesses at the drive-side plate width end, the plate width center, and the work-side plate width end are continuously measured until the roll reverses and the plate passes through the multi-point thickness gauge, and these are input into the 10 wedge control. Then, the average plate wedge value in the plate length direction at these three points is obtained using the formula (1), and the average plate thickness value at the plate width center is obtained. Suffixes for the i-th pass are added to these. Also, the plate wedge ratio is defined by the following formula. That is, [Number] TIFF0007685721000005.tif7153 exists. That is, from the time when the material to be rolled reaches the multi-point thickness gauge in the first odd-numbered pass i where the plate thickness can be measured, the average plate thickness at the plate width center measured while the material to be rolled reverses and turns off the multi-point thickness gauge TIFF0007685721000006.tif13153 is used, which is one of the features of the present invention.

[0014] By the way, in actual rolling, it is known that the material to be rolled causes metal flow (lateral flow) in the plate width direction during rolling. (For example, see Non-Patent Document 3.)

[0015] This metal flow serves as a relaxation action for flatness, narrowing due to plate meandering, and further camber. The relationship including this relaxation action is basically an empirical formula or empirical value determined by experiments. The relationship between plate crown and plate flatness, etc. is described in Non-Patent Document 3, but the relationship between plate wedge and plate flatness, narrowing due to plate meandering, and camber, etc. is not described. When the plate wedge changes, the elongation in the rolling direction of the plate in the plate width direction becomes different. For this reason, tensile force and compressive force corresponding to the change in the wedge amount act on the plate, which is related to the Young's modulus of the plate, but when it exceeds the buckling force of the plate, it appears as, for example, plate flatness. Also, meandering, narrowing, or camber occurs. Furthermore, since the plate generates metal flow in the plate width direction, it is currently difficult to formulate a precise mathematical formula for the overall limit, etc. Taking the above into consideration, the inventors have found that the relationship between the plate wedge ratio on the outlet side of the i-th pass and the plate wedge ratio on the outlet side of the (i + 1)-th pass, within the range where no flatness defects, narrowing due to meandering, or camber of the plate occur, is as shown in the following equation (3). That is, the plate wedge ratio difference limit equation is as follows: [Equation] TIFF0007685721000008.tif14152 γ and δ are determined by experiments that include the relaxation effect of the elongation difference limit of the plate described above, or are experimental formulas or experimental values. That is, if the target value of the outlet-side plate wedge of the (i + 1)-th pass is selected so that equation (3) holds on the outlet sides of the i-th pass and the (i + 1)-th pass, flatness defects, narrowing due to meandering, or camber of the plate will not occur. From equation (3), the target value of the outlet-side plate wedge of this pass is obtained before rolling in the (i + 1)-th pass, and this should be made as small as possible within the plate wedge ratio difference limit equation. In accordance with this policy, the MEAS value in the i-th pass in equation (3) is measured TIFF0007685721000009.tif15153 and is determined. That is, one feature of this patent is to obtain the target value of the outlet-side plate wedge after control setting so that, in the (i + 1)-th pass, within the plate wedge ratio difference limit and, moreover, the outlet-side plate wedge is as close as possible to the zero value of the target value.

[0016] Next, another feature of this patent is that the inventors have found that in the (i + 1)-th pass, the target value of the outlet-side plate wedge is the sum of the product of the roll gap leveling correction amount in the (i + 1)-th pass and an influence coefficient, and the value of the inlet-side plate wedge that is inherited on the outlet side. That is, [Equation] TIFF0007685721000011.tif7152 is the influence coefficient indicating how much the wedge changes. TIFF0007685721000012.tif is a genetic coefficient indicating 7153 ka. As described above, equation (4) will be referred to as the leveling, influence coefficient, and genetic coefficient equation below.

[0017] These influence coefficients and genetic coefficients can be calculated for all steel grades, plate thicknesses, and plate widths to be rolled by simultaneously solving the deformation equations of the rolling mill, rolls, and material to be rolled. (See, for example, Non-Patent Document 2)

[0018] These calculations are quite extensive and, although they can be calculated online, the equipment becomes large. Therefore, in practice, they are calculated using an offline computer (not shown), and these calculation results are summarized into algebraic expressions such as steel grade, plate thickness, plate width, and rolling load so that they can be used by a PLC controller. Then, these algebraic expressions are input into the controller that controls and sets the wedge shown at 10 in FIG. 2. Furthermore, in the mill setting calculation shown at 13, mill setting calculations are performed for all passes of each slab, and the steel grade, plate thickness, plate width, rolling load, etc. are calculated. And for all passes, the influence coefficient and genetic coefficient are obtained using the above algebraic expressions. The above are the other features of this patent.

[0019] Utilizing what has been described above, in the control and setting of the wedge shown at 10 in FIG. 2, before rolling in the (i + 1)th pass from equation (4),

Equation

[0020] Furthermore, in the next odd-numbered pass, the (i + 2)th pass, the relationship between the i-th pass and the (i + 1)th pass described above is used in the same way before rolling. That is, assuming that the target value of the plate wedge on the exit side in the (I + 1)th pass can be achieved, in equation (3), the pass is advanced by one,

Equation

Equation

[0021] Also, after rolling one slab, the correction amount of roll gap leveling integrated up to the final pass with control settings for this slab is learned and control-set for the next slab, and the same learning and control settings are performed for each successive slab. In this case, learning methods such as exponential smoothing method, smoothing in a first-order lag system, and other learning methods can be considered. As described above, it is another feature of this patent that the plate wedge of the rolled plate over the entire plate length can be made zero or close to zero as the desired value, with good flatness, no curl at the tip of the plate, no camber or draw of the entire plate, and a plate with good dimensional accuracy of the product can be rolled.

Example

[0022] In the control setting of the plate wedge described in the above Example 1, when the plate thickness reaches the reference plate thickness, the plate wedge and the exit side plate thickness are measured in the i-th pass, which is an odd pass. Then, the target value of the exit side plate wedge is obtained so as to fall within the plate wedge ratio difference limit for the next (i + 1)-th pass, and the control setting amount of roll gap leveling for achieving this is obtained and set in the rolling mill before rolling for rolling. Also, for the next (i + 2)-th pass, assuming that the target value of the exit side wedge of the (i + 1)-th pass has been achieved, this is used as the entrance side plate wedge, and the target value of the exit side plate wedge of the (i + 2)-th pass is obtained in the same manner as the (i + 1)-th pass using the set calculation exit side plate thickness. Then, the control setting amount of roll gap leveling for the (i + 2)-th pass is obtained and control-set before rolling for rolling. And the same calculations are performed until the final pass, and finally the control setting is performed so that the plate wedge becomes zero as the target value. By the way, after the (i + 2)-th pass, the plate wedge and the exit side plate thickness can be measured in odd passes until the final pass. In the control setting of the plate wedge, it is generally expected that using the measured values as much as possible will improve the control setting accuracy. Therefore, in this embodiment, the outlet side plate wedge and the outlet side plate thickness are measured at the (i + 2) pass of the odd passes, and the same calculations as in Example 1 are performed at the next (i + 3) pass and (i + 4) passes, respectively, and control settings are made before rolling to improve the control setting accuracy. Similarly, this calculation and operation are repeated until the final pass. That is, measurement is performed at odd passes, control setting is performed at the next even pass, and control setting is performed at the next odd pass. Also, measurement is performed at this odd pass, and control setting is repeated at the next two passes. This is carried out until the final pass. In addition, when rolling of one slab is completed, the correction amount of roll gap leveling integrated up to the final pass where control setting was performed for this slab is learned and control set for the next slab, and learning and control setting are performed in the same manner for each successive slab. Another feature of this patent is that in this case, learning methods such as exponential smoothing method, smoothing in a first-order lag system, and other learning methods can be considered. As described above, another feature of this patent is that it is possible to make the plate wedge of the rolled plate over the entire plate length approach zero or near zero of the desired value, the flatness of the plate is good, there is no skew at the tip of the plate, no camber or draw of the entire plate, and a plate with good dimensional accuracy of the product can be rolled.

Example

[0023] The above was the case of single-stand reversible rolling. On the other hand, in the arrangement of roughing mills of hot strip mills, there are those in which single-stand rolling mills are arranged separately in 4 to 5 stands instead of tandem, those in which a reversible rolling mill is first arranged and then another reversible rolling mill is arranged, those in which a single-stand rolling mill is first arranged, then a reversible rolling mill is arranged, and finally a 2-stand tandem rolling mill is arranged, and so on. Although the arrangements of rolling mills in such an arrangement are different for each single-stand rolling mill, since rolling is performed in order at each rolling mill, it is considered that many single-stand rolling mills are arranged independently. Here, a multi-point thickness gauge is installed on the outlet side of the final stand of rough rolling. First, assume that material A is rolled first, then material B, and then material C... in the rolling order. First, measure the plate wedge and the outlet plate thickness over the entire length at the outlet side of the final pass of Material A, and obtain the average value of each. Next, use these values to obtain the plate wedge ratio at the outlet side. If the outlet plate thickness of the next Material B in the final pass is the same as that of Material A, use this value. If the outlet plate thickness of the next Material B in the final pass is different from that of Material A, take the final pass of Material A as the i-th pass, and obtain the plate wedge ratio at the outlet side of the i-th pass. Next, also take the final pass of Material B as the i-th pass. Then, using the set calculation value for the outlet plate thickness of Material B, make the plate wedge ratios in the final passes of Material A and Material B the same. This is defined as the plate wedge deviation of Material B. Based on these, sequentially determine the target value of the outlet plate wedge so that it falls within the plate wedge ratio difference limit for the upstream passes, and obtain the control setting amount for leveling using the leveling, influence coefficient, and genetic coefficient formulas. Such a method is exactly the same as that in Patent Document 1, and the control settings for roll gap leveling in all passes of Material B are determined. These values are set and controlled in the rolling mill before rolling to perform rolling. However, the control setting for Material B is only done once before rolling because Material B does not exist in all passes simultaneously. Also, after rolling one slab is completed, learn and control set the correction amount of the roll gap leveling integrated up to the final pass where control settings were made in each pass for this slab for the next slab, and learn and control set in the same way for each successive slab. This is another feature of this patent. For the learning method in this case, for example, an exponential smoothing method, smoothing in a first-order lag system, or other learning methods can be considered. As described above, another feature of this patent is that the plate wedge of the rolled plate over the entire length of the plate can be made zero or close to zero as the desired value, the flatness of the plate is good, there is no warping at the tip of the plate, no camber or draw in the whole plate, and a plate with good dimensional accuracy of the product can be rolled.

[0024] Note that the above control setting is a feed-forward control setting measured in odd passes and performed in the next pass or the pass after that. However, although it is also conceivable to perform feedback control on the remaining material to be rolled measured in odd passes and measured in the same pass, a wedge step will occur on the plate.

Industrial Applicability

[0025] As described above, in the method for setting and controlling the plate wedge in the rolling of metals and the like according to the present invention, since plates with the same thickness can be rolled over the entire length on the working side and the driving side, there are no flatness defects in the plates, no widthwise plate bending at the leading and trailing ends of the plate during rolling, no narrowing of the plate due to the meandering of the plate during rolling, and no camber in the plate, so that the rolling operation can be carried out normally. In addition, the dimensional accuracy of this plate material is improved because the plate thickness in the plate width direction becomes uniform over the entire length of the plate.

Explanation of Signs

[0026] 1 Working side 2 Driving side 3 Plate width 4 Even pass direction 5 Odd pass direction 6 Edger 7 Horizontal rolling mill 8 Multipoint thickness gauge 9 Level control 10 Wedge control and setting 11 Material to be rolled 12 Adder 13 Mill setting calculation 14 Rolling order 15 Upper roll 16 Lower roll 17 Roll gap detection 18 Screwdown device

Claims

1. A method for controlling and setting a plate wedge in a rolling facility for rough rolling or heavy plate rolling of a hot strip mill that reversibly rolls a plate material hot, comprising a multi-point thickness gauge that measures the plate thickness in the rolling direction at multiple points in the plate width direction on the exit side of the reversible rolling mill, a mill setting computer for setting the rolling mill, and a roll gap leveling device on the working side and the drive side. During odd passes when rolling progresses to a plate thickness measurable by the multi-point thickness gauge, measure the plate thickness on the working side and the drive side, obtain the plate wedge, divide by the measured plate thickness at the center of the plate width, and use this as the ratio of the plate wedge on the entry side of the next even pass. Determine the target value of the plate wedge on the exit side of the next even pass such that the difference from the ratio of the plate wedge on the exit side obtained by dividing the target value of the plate wedge on the exit side of the next even pass by the exit-side plate thickness at the center of the plate width in the setting calculation is within the limit of the plate wedge ratio difference. Calculate the control setting quantity for roll gap leveling by a formula that is the sum of this value multiplied by the influence coefficient for the control setting quantity of roll gap leveling in the next even pass and the plate wedge on the entry side being transmitted to the exit side by the inheritance coefficient. Set this value before rolling and perform rolling. Also, during the next odd pass, use the target value of the plate wedge on the exit side in the previous even pass as the plate wedge on the entry side, and obtain the control setting quantity for roll gap leveling by performing a similar calculation using the plate thickness at the center of the plate width in the setting calculation. Set this value before rolling and perform rolling. Repeat such calculations until the final pass to obtain the control setting quantity for roll gap leveling for each pass. Set this value in the rolling mill before rolling each pass and perform rolling to roll a plate with a desired plate wedge (zero) over the entire length of the plate. Furthermore, learn the value of roll gap leveling in the final pass rolling state of the preceding material and control and set it for the first pass of the next material to be rolled to obtain a product with an even more accurate plate wedge. A method for controlling and setting a plate wedge.

2. A method for controlling and setting a plate wedge according to claim 1, wherein after rolling progresses and reaches a plate thickness measurable by a multi-point thickness gauge, the plate thicknesses on the working side and the driving side are measured in all odd passes thereafter to obtain a plate wedge, which is divided by the measured plate thickness at the center of the plate width to obtain the plate wedge ratio on the inlet side for the next even pass. The target value of the plate wedge on the outlet side for the next even pass is determined such that the difference from the plate wedge ratio obtained by dividing the target value of the plate wedge on the outlet side at the center of the plate width in the setting calculation by the outlet side plate thickness is within the plate wedge ratio difference limit. The control setting amount for roll gap leveling for the next even pass is obtained by an equation that is the sum of this value multiplied by the influence coefficient and the inlet side plate wedge inherited to the outlet side by the inheritance coefficient, and is set before rolling and then rolled. Also, in the next odd pass, the target value of the plate wedge on the outlet side in the previous even pass is used as the inlet side plate wedge, and the control setting amount for roll gap leveling is obtained by a similar calculation using the plate thickness at the center of the plate width in the setting calculation, and is set before rolling and then rolled. The method for controlling and setting a plate wedge according to claim 1, wherein such calculations are repeated until the final pass to obtain the control setting amount for roll gap leveling, which is set in the rolling mill before rolling in each pass and then rolled, thereby rolling a plate with a desired plate wedge (zero) over the entire length of the plate.

3. A method for controlling and setting a plate wedge in a hot rough rolling facility having a reversible rolling mill alone with 2 to 3 stands, a one-way hot rough rolling facility having 4 to 6 single rough rolling mills and each stand performing one rolling on one slab, or a hot rough rolling facility having a reversible rough rolling mill and a tandem rough rolling facility with 2 stands in the final pass, wherein A multi-point thickness gauge for measuring the plate thicknesses on the working side, the driving side, and the center of the plate width is installed on the outlet side of the final pass or the final rolling mill. The target values of the plate wedges on the inlet side and the outlet side (control setting target values) for each pass of the previous material are determined. The plate wedge and the plate thickness at the center of the plate width are measured in the final pass of the previous material, and the plate wedge is divided by the plate thickness at the center of the plate width to obtain the plate wedge ratio on the outlet side of the final pass of the previous material. Next, the plate wedge ratio on the outlet side of the final pass of the previous material and the plate wedge ratio on the outlet side of the final pass of the next material are set to the same value. Next, the difference between the plate wedge ratio on the outlet side of the final pass of this next material and the plate wedge ratio on the inlet side of the final pass of the next material (the value to be obtained) is put into the plate wedge ratio difference limit formula to determine the target value of the plate wedge ratio on the inlet side of the final pass of the next material. This value is multiplied by the plate thickness at the center of the plate width on the inlet side to calculate the target value of the plate wedge on the inlet side of the final pass. Similarly, for each upstream path of the next material, the target values of the plate wedges at the inlet and outlet of each upstream path are obtained. The target values of the plate wedges at the inlet and outlet of each path (control setting target values) are substituted into the equation where the sum of the product of the influence coefficient and the roll gap leveling amount to be controlled and the product of the genetic coefficient and the target value of the inlet plate wedge equals the target value of the outlet plate wedge, and the roll gap leveling amount to be controlled for each path is obtained. These are controlled and set before rolling and then rolled. A method for controlling and setting the plate wedge, characterized in that the outlet plate wedge of the final path is set to zero or a small value.

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