JP5811051B2 - Method for cold rolling metal plate and method for producing metal plate - Google Patents

Description

  The present invention relates to a method for cold rolling a metal plate and a method for producing a metal plate using the same.

  Among the metal plates manufactured through cold rolling, for example, cold rolled steel plates represented by steel plates for automobiles are made of high-tensile steel plates ( In the following, the use of “high-tensile steel”) is increasing.

  High-tensile steel is manufactured by adjusting additive elements in order to increase strength, and further performing composition control and structure control using metallurgy phenomena such as precipitation and phase transformation by cooling after heating. In general, when the strength is increased, ductility (elongation) decreases, and in the cold rolling process for producing high-tensile steel, if excessive tension is applied to the material to be rolled, cracking occurs and there is a risk of fracture (sheet cracking). Rise.

  On the other hand, it is known that the heat treatment in the rolling process included in the manufacturing process of the hot-rolled steel sheet that is the base material of the cold-rolled steel sheet also affects the final product characteristics. At the time of manufacturing the hot-rolled steel sheet, the steel sheet is water-cooled on a run-out table on the exit side of the finishing mill. At this time, unevenness of water flow and water film on the steel sheet is likely to occur, and furthermore, since there is an unstable region of heat transfer on the steel sheet surface called transition boiling, uneven cooling of the hot-rolled steel sheet is likely to occur. In addition, since generally the edge part of a board is easy to cool, the width direction edge part of a hot-rolled steel plate is relatively hard, and its ductility is also low. Further, water tends to stay at the tip and tail ends of the coil, which is a portion where no tension is applied between the finishing mill and the downcoiler on the run-out table, due to the defective shape of the steel plate. Therefore, uneven cooling can occur even in the longitudinal direction of the steel sheet. High-tensile steel is designed to increase the strength by changing the structure by cooling, so it is particularly sensitive to the cooling rate and temperature, and compared to ordinary steel, the strength variation due to uneven cooling (deformation resistance) Variations are likely to occur.

  Thus, in the hot-rolled base material used for cold rolling, variation occurs in the deformation resistance in the longitudinal direction and the width direction. Therefore, in the cold rolling process, the risk of breakage during rolling is further increased due to the hunting of the plate thickness due to fluctuations in rolling load and the instability of the shape, together with the low ductility of the end in the width direction. When the steel sheet breaks, the operation rate decreases due to the processing operation, and an unrolled part and a defective part are generated at the time of re-passing, so that the yield is greatly reduced. In order to avoid such a situation, measures are taken such as trimming the widthwise end of the hot rolled base metal or cutting the leading end to remove a portion with unstable mechanical properties. However, even if such measures are taken, it is not possible to prevent a decrease in yield. Therefore, development of the technique which prevents the plate fracture | rupture in a cold rolling process is calculated | required.

  As a technique that can prevent sheet breakage in the cold rolling process, for example, in Patent Document 1, the elongation at break of a material to be rolled is obtained in advance, and the rolling reduction of the sheet width end in each rolling stand or each rolling pass is determined. A cold rolling method is disclosed in which edge rolling at the edge of the sheet width is prevented by setting a rolling schedule so as to exceed the limit rolling ratio determined from the average rolling reduction and tensile breaking elongation of the entire sheet width. Further, in Patent Document 2, a roll that is rotatably supported on the exit side of the cold rolling mill is disposed, and the roll is pressed against the center of the sheet width of the material to be rolled. A cold rolling method has been disclosed in which the tension applied to both ends of the rolled material sheet width on the exit side is reduced to prevent ear cracks and sheet breakage. Patent Document 3 discloses a method for preventing the cracking of a cold-rolled plate, in which both side edges of a metal plate coil to be cold-rolled are heated and softened and then cold-rolled while rewinding the metal plate coil. It is described that heating is preferably performed by pressing a hot plate against both side edges of the metal plate coil.

Japanese Patent No. 3156568 Japanese Patent Laid-Open No. 6-87005 JP-A-4-371314

  However, the technique disclosed in Patent Document 1 is based on the premise that rolling is performed stably. Therefore, when the rolling load or the shape is changed due to the change in deformation resistance of the base material and an over tension is generated at the end portion in the width direction, the technique disclosed in Patent Document 1 cannot be applied. Moreover, in high strength steel with high strength, the rolling reduction may not be sufficiently increased due to restrictions such as rolling load and motor power. Further, it is considered that the effect of reducing the tension at the end in the width direction obtained by the technique disclosed in Patent Document 2 is slight, and excessive tension between the stands when the roll is excessively pressed against the material to be rolled. This may cause adverse effects on rolling. Furthermore, since the technique disclosed in Patent Document 2 assumes a condition in which the plate thickness on the first stand outlet side is relatively thick, if this technique is applied to the downstream stand, adverse effects such as wrinkles and breakage will occur. It is considered that there is a high possibility of Moreover, the technique currently disclosed by patent document 3 assumes the rolling of aluminum, and the heating temperature required is 350 degreeC in the Example. However, the temperature at which the steel plate softens is 500 ° C. or higher, and in addition, the steel plate is less likely to conduct heat than aluminum. Furthermore, since the width of the end in the width direction where the strength varies is about 100 mm, when the technique disclosed in Patent Document 3 is applied to cold rolling of a steel sheet, the necessary heating equipment becomes large, heat treatment energy, etc. There is a concern about the cost increase. Therefore, even if the techniques disclosed in Patent Documents 1 to 3 are combined, it is difficult to perform cold rolling at a low cost while preventing sheet breakage of the material to be rolled in which strength variation exists.

  Therefore, the present invention has an object to provide a cold rolling method for a metal plate and a method for manufacturing a metal plate using the same, which can prevent a plate passing trouble such as a plate breakage in rolling at low cost. And

  The present invention will be described below.

The first aspect of the present invention is the difference between the shape of the rolled material measured on the exit side of the rolling mill during cold rolling and the predicted shape of the rolled material obtained from the rolling conditions of the rolling mill. And, using the deformation resistance distribution information in the width direction of the rolled material obtained in advance, the deformation resistance distribution in the width direction of the rolled material on the upstream side of the rolling mill is estimated, and the width direction end of the rolled material is estimated. When the deformation resistance of the part is higher than the deformation resistance of the central part in the width direction, the rolling material is cold-rolled by using a rolling mill set to have an ear wave shape, and the width direction end of the rolling material is When the deformation resistance of the part is lower than the deformation resistance of the central part in the width direction, a cold rolling method of the metal plate is performed by cold rolling the material to be rolled using a rolling mill set to have a middle stretch shape It is.

Here, in the present invention, the “rolling mill set to have an acoustic wave shape” operates with a setting in which the width direction end portions (both ends) are easier to extend than the width direction center portion of the material to be rolled. Say rolling mill. Further, in the present invention, “a rolling mill set to have a middle-elongation shape” means rolling that operates at a setting in which the central portion in the width direction is easier to extend than the end portions (both ends) in the width direction of the material to be rolled. Say the machine. In the present invention, the method for measuring the shape of the material to be rolled is not particularly limited. For example, the shape is measured by a known method such as measurement using a shape meter (shape measuring means) installed on the exit side of the rolling mill. be able to. In the present invention, the method for predicting the shape after rolling of the material to be rolled from the rolling conditions of the rolling mill is not particularly limited. For example, “Theory and practice of plate rolling” (edited by the Japan Iron and Steel Institute) The numerical calculation method described in Chapter 4 can be used.

  Further, in the first aspect of the present invention, the material to be rolled has a deformation resistance distribution in the width direction specified in advance, and the deformation resistance at the end in the width direction determined from the deformation resistance in the center in the width direction. If it is too high, the setting value of the shape control actuator of the rolling mill is set to a setting value that is an ear wave shape than the setting value derived from the setup calculation that assumes that the deformation resistance of the material to be rolled is uniform in the width direction. When the material to be rolled is cold-rolled and the deformation resistance at the specified width direction end is lower than the deformation resistance at the center in the width direction, the setting value of the shape control actuator of the rolling mill is derived from the setup calculation. The material to be rolled may be cold-rolled at a set value that is a middle stretch shape rather than the set value.

  Here, in the present invention, the method for specifying the deformation resistance distribution in the width direction of the material to be rolled in advance is not particularly limited. For example, a sample is taken from the leading end of the steel strip after hot rolling, The method of cutting out a test piece from several places of the width direction and evaluating by a tensile test, the method of converting from hardness measurement to deformation resistance, etc. can be mentioned.

  Further, in the first aspect of the present invention, during the cold rolling, the rolling load applied from the rolling mill to the material to be rolled is measured, and the shape of the rolling mill is determined according to the change in the measured rolling load. When the setting of the control actuator is changed and the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center portion in the width direction of the material to be rolled It is preferable that the amount of change in the set value of the upper shape control actuator is larger than when the change in rolling load is not caused by the change in the deformation resistance distribution in the width direction of the material to be rolled.

  Here, in the present invention, the “rolling mill shape control actuator” refers to an actuator that controls, for example, the width direction position of the rolling roll, the crown, the degree of inclination of the upper and lower rolling rolls, and the like. Further, the “width direction center portion of the material to be rolled” refers to a region including the center of the material to be rolled in the width direction. For example, in the case of a middle stretched shape, the other region (the region including one end in the width direction and the width direction). A region extending relatively than a region including the other end. In the present invention, the method for measuring the rolling load is not particularly limited, and for example, it can be measured by a known method such as measurement using a load cell attached to a rolling mill. In addition, “when the change in rolling load is not caused by the change in the deformation resistance distribution in the width direction of the material to be rolled” means, for example, when the rolling load changes due to a change in the lubrication state due to a change in rolling speed Say.

  Further, in the first aspect of the present invention, during the cold rolling, the rolling load applied from the rolling mill to the material to be rolled is measured, and the shape of the rolling mill is determined according to the change in the measured rolling load. When the setting of the control actuator is changed and the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance at the width direction end of the material to be rolled More than the case where the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center portion in the width direction of the material to be rolled. It is preferable to reduce the amount of change.

  Here, the “width direction end portion of the material to be rolled” refers to a portion excluding the center portion in the width direction of the material to be rolled, for example, in the case of an ear wave shape, than other regions (width direction center portion). It refers to a relatively elongated area.

  A second aspect of the present invention is a method for manufacturing a metal plate, comprising a step of cold rolling a metal plate using the method for cold rolling a metal plate according to the first aspect of the present invention.

  A material to be rolled whose deformation resistance at the width direction end portion is higher than the deformation resistance at the width direction center portion is likely to become a middle stretch shape when rolled, and the deformation resistance at the width direction end portion is lower than the deformation resistance at the width direction center portion. The material to be rolled tends to have an ear wave shape when rolled. In the present invention, the material to be rolled is likely to be cold-rolled using a rolling mill that operates with a setting that is easy to make an ear-wave shape, and the ear-wave shape is used with a rolling mill that operates with a setting that is easy to make a middle-stretch shape Since the material to be rolled is cold-rolled, it is possible to suppress excessive middle elongation and ear waves, thereby allowing the plate to break due to excessive middle elongation and narrowing due to excessive ear waves. The occurrence of plate trouble can be suppressed. Therefore, according to the present invention, there is a variation in deformation resistance (hereinafter sometimes referred to as “tensile strength” or “strength”) in the width direction of the material to be rolled, and this varies in the longitudinal direction. Even if it is a case, generation | occurrence | production of the boarding trouble by cold rolling can be suppressed, and it becomes possible to prevent the fall of an operation rate or a yield. Moreover, in this invention, since the heating apparatus which heats the width direction edge part is not an essential structure, it is possible to suppress an increase in cost.

It is a figure which shows the relationship between the width direction position and yield stress. It is a figure which shows the relationship between the width direction position and tensile strength. It is a figure which shows the shape measurement result in the last stand exit side of cold rolling. FIG. 3A is a diagram showing the shape measurement result of the coil tip end portion, and FIG. 3B is a diagram showing the shape measurement result of the coil tail end portion. It is a figure which shows the numerical simulation result of cold rolling. 4A is a diagram showing a numerical simulation result of the coil tip, FIG. 4B is a diagram showing a numerical simulation result of the coil tail, and FIG. 4C is a deformation resistance in the width direction. It is a figure which shows the numerical simulation result in case where is constant. It is a figure which shows the relationship between the tensile strength of the sample used when investigating the relationship between the change of rolling load, and a shape change, and the distance from the width center . FIG. 5A is a diagram showing the relationship between the tensile strength of a sample whose deformation resistance in the width direction is not uniform and the distance from the center of the width, and FIG. 5B is a diagram of the sample whose deformation resistance in the width direction is uniform. It is a figure which shows the relationship between the tensile strength and the distance from the width center . It is a figure which shows the calculation result of the rolling load of each stand used when investigating the relationship between the change of rolling load, and a shape change. FIG. 6A is a diagram showing the rolling load of each stand when a sample having a non-uniform deformation resistance in the width direction is cold-rolled, and FIG. 6B shows a sample having a uniform deformation resistance in the width direction. It is a figure which shows the rolling load of each stand at the time of cold rolling. It is a figure which shows the relationship between a rolling load and elongation difference rate . FIG. 7A is a diagram showing the relationship between the rolling load and the elongation difference when a sample having a non-uniform deformation resistance in the width direction is cold-rolled, and FIG. 7B is a uniform deformation resistance in the width direction. It is a figure which shows the relationship between the rolling load when the sample which is is cold-rolled, and elongation difference rate . It is a figure explaining the change of the elongation difference rate of the width direction edge part with respect to the change of rolling load. It is a figure explaining the relationship between the shape change of the width direction edge part when the deformation resistance of the width direction is uniform, and the case where it is not uniform, and the shape control amount by a shape control actuator. It is a block diagram explaining the cold rolling method of the metal plate concerning this invention. It is a figure which shows the result of a board trouble occurrence ratio. It is a figure which shows the result of a board trouble occurrence ratio.

  Embodiments of the present invention will be described below. In addition, the form shown below is an illustration of this invention and this invention is not limited to the form shown below.

  By performing a tensile test on samples taken from the front end, center, and tail end of the coil after hot rolling of 980 MPa class high-tensile steel, the yield stress (YP) and tensile strength ( TS) was measured. FIG. 1 shows the relationship between the width direction position and the yield stress (YP), and FIG. 2 shows the relationship between the width direction position and the tensile strength (TS). The vertical axis in FIG. 1 is the yield stress (YP) [MPa], the horizontal axis is the width direction position [mm], the vertical axis in FIG. 2 is the tensile strength (TS) [MPa], and the horizontal axis is the width direction position [mm]. mm]. 1 and 2, the width direction position 0 mm corresponds to the center in the width direction.

  As shown in FIG. 1 and FIG. 2, the width direction end portion is stronger than the width direction center portion at the longitudinal end portion and the center portion. The central part in the width direction was stronger than the end part in the direction. Moreover, the intensity | strength of the width direction center part changed in the front-end | tip part, the center part, and the tail end part. Further, from FIGS. 1 and 2, the difference between the maximum value and the minimum value of the tensile strength in the width direction was larger than the difference between the maximum value and the minimum value of the yield stress in the width direction. This is considered due to work hardening.

When the coil hot-rolled under the same condition as the coil from which the sample whose measurement results are shown in FIG. 1 and FIG. 2 is cold-rolled using a tandem rolling mill equipped with five stands (rolling mills), The shape measurement result by the shape meter installed on the exit side of the final stand (fifth stand) is shown in FIG. FIG. 3A shows the shape measurement result of the coil tip, and FIG. 3B shows the shape measurement result of the coil tail. 3 (a) and 3 (b), the vertical axis indicates the actual shape [Iunit] calculated from the measured value of the tension distribution in the width direction of the plate, the horizontal axis indicates the width direction position [mm], and the arrow indicates the coil This means a region from one end to the other end in the width direction. Here, “Iunit” is a flatness display unit expressed as 1 Iunit when the strain inherent in a sample having a reference length of 1 m is 0.01 mm in terms of the difference in elongation. The same applies to the following.
As shown in FIG. 3 (a), the coil tip portion whose width direction end portion is higher in strength than the width direction center portion has a middle extension shape, and the width direction center portion is higher in strength than the width direction end portion. As shown in FIG. 3 (b), the coil tail end portion has an otic wave shape. The rolling conditions at this time are as follows: plate width: 1000 mm, base material thickness: 2.4 mm, finishing thickness: 1.2 mm, total rolling reduction: 50%, rolling reduction of the first to third stands: about 17%, The rolling reduction of the fourth stand: 12%, the rolling reduction of the fifth stand: 1%, and when determining the rolling conditions of the first to fifth stands, the distribution of deformation resistance in the coil width direction is not considered. .

  The frequency of occurrence of sheeting troubles such as breaking and narrowing during cold rolling is related to the shape of the material to be rolled upstream from the final stand, so the shape of the material to be rolled upstream from the final stand (rolling) It is preferable to grasp the shape) and appropriately change the rolling conditions of the stand arranged upstream of the final stand as necessary. However, in the tandem rolling mill having the five stands, generally, a shape meter is not arranged between the stands, and the rolling shape between the stands cannot be specified. Then, the rolling shape between stands was evaluated by performing numerical simulation. The results are shown in FIG. 4A is a diagram showing a numerical simulation result of the coil tip, FIG. 4B is a diagram showing a numerical simulation result of the coil tail, and FIG. 4C is a deformation resistance in the width direction. It is a figure which shows the numerical simulation result in case where is constant. 4A to 4C, the vertical axis represents the difference (elongation differential ratio) [Iunit] from the center of the width direction, and the horizontal axis represents the distance [mm] from the center in the width direction. The part where the elongation difference rate is a positive value means that it extends beyond the center in the width direction, and the part where the elongation difference rate is a negative value means that it does not extend beyond the center in the width direction. Yes. Further, “F1” means the shape on the exit side of the stand arranged on the most upstream side in the plate passing direction among the five stands, and “F2” is the stand arranged second from the upstream side in the plate passing direction. "F3" means the shape on the exit side of the stand arranged third from the upstream side in the plate passing direction, and "F4" is the fourth from the upstream side in the plate passing direction. "F5" means the shape on the exit side of the stand arranged on the most downstream side in the plate passing direction.

  As shown in FIG. 4A, at the coil tip where the deformation resistance (tensile strength) at the end in the width direction is higher than the deformation resistance (tensile strength) at the center in the width direction, all the stands are in a middle-extending shape. As shown in FIG. 4B, at the tail end of the coil where the deformation resistance (tensile strength) at the width direction end is lower than the deformation resistance (tensile strength) at the center in the width direction, all the stands have ear waves. Each of the shapes showed the same tendency as the actual measurement value measured with the shape meter on the exit side of the final stand. As described above, the result of the numerical simulation assuming cold rolling with 5 stands is in good agreement with the actual measurement result, indicating that this simulation is appropriate.

  Moreover, as shown in FIG.4 (c), when the rolling material which has the constant deformation resistance (tensile strength) of the width direction is cold-rolled with a tandem rolling mill provided with five stands, it will become an ear wave shape. It was shown to be. This result was similar to the result shown in FIG. 4B, but was significantly different from the result shown in FIG. As shown in FIG. 3A and FIG. 4A, when a portion where the deformation resistance at the end in the width direction is higher than the deformation resistance at the center in the width direction is rolled, the end in the width direction extends beyond the center in the width direction. As shown in FIG. 4 (c), the material to be rolled is rolled using a tandem rolling mill having a shape control actuator set to roll the material to be rolled whose deformation resistance in the width direction is constant. Then, the width direction edge part extends rather than the width direction center. Therefore, when using a tandem rolling mill set to roll a material to be rolled with a constant deformation resistance in the width direction, when rolling a portion where the deformation resistance at the end in the width direction is higher than the deformation resistance at the center in the width direction. When an excessive tension is applied, for example, when the material to be rolled is high-tensile steel, there is a possibility of breaking.

  As described above, the rolling shape greatly changes due to the difference in deformation resistance in the width direction because the rolling load increases in the portion with high deformation resistance and the flat amount of the work roll of the rolling mill increases, so that the reduction in the sheet thickness direction occurs. This is probably because the amount is reduced and the elongation strain is also reduced.

  As described above, when a material to be rolled that has a difference in deformation resistance in the width direction is cold-rolled, the tendency of the difference in deformation resistance in the width direction (whether the end in the width direction has a higher deformation resistance than the central portion in the width direction). Alternatively, the shape (rolling shape) of the material to be rolled after cold rolling is greatly different depending on whether the central portion in the width direction has higher deformation resistance than the end portion in the width direction. Therefore, even if a rolling material having a shape control actuator set up on the assumption that the deformation resistance of the material to be rolled is uniform in the width direction, the material to be rolled having a difference in deformation resistance in the width direction is rolled. In some cases, an appropriate rolled shape may not be obtained. Especially, immediately after changing the running distance, there are problems in passing the plate such as breaking of the metal plate due to excessive middle elongation and narrowing of the metal plate due to excessive ear waves. There is a fear. The present inventors have conducted the above investigation, and when the deformation resistance at the width direction end of the material to be rolled is higher than the deformation resistance at the width direction center, the set value of the shape control actuator of the rolling mill is set to the material to be rolled. The rolling resistance of the material to be rolled is set to be a setting value that is an ear-wave shape rather than the setting value derived from the setup calculation assuming that the deformation resistance is uniform in the width direction. When the deformation resistance is lower than the deformation resistance at the center portion in the width direction, the set value of the shape control actuator of the rolling mill is set to a set value that becomes a middle elongation shape than the set value derived from the set-up calculation, and the material to be rolled As a result of cold rolling, it was found that troubles in sheet passing could be reduced, and the present invention was completed.

  In addition, a change in strength of the material to be rolled also appears as a change in rolling load as a behavior during rolling. Therefore, the relationship between the change in rolling load and the change in shape was investigated for each of the samples having a difference in deformation resistance in the width direction and the samples having a uniform deformation resistance in the width direction. FIG. 5A shows the relationship between the tensile strength (TS) and the position in the width direction of the sample having a difference in deformation resistance in the width direction, and the tensile strength (TS) of the sample in which the deformation resistance is uniform in the width direction. ) And the position in the width direction are shown in FIG. 5A and 5B, the vertical axis represents the tensile strength (TS) [MPa], and the horizontal axis represents the position in the width direction [mm]. Also, FIG. 6A shows the rolling load at each stand when rolling a sample having a difference in deformation resistance in the width direction, and the rolling load at each stand when rolling a sample having a uniform deformation resistance in the width direction. Are shown in FIG. The vertical axis | shaft of Fig.6 (a) and FIG.6 (b) is the rolling load P [ton]. 7A shows the shape of the outlet side of the stand (fourth stand) arranged fourth from the upstream side in the sheet passing direction when a sample having a difference in deformation resistance in the width direction is rolled. FIG. 7B shows the shapes on the exit side of the stand (fourth stand) arranged fourth from the upstream side in the sheet passing direction when the sample having uniform deformation resistance in the direction is rolled. In FIG. 7A and FIG. 7B, the vertical axis represents the elongation difference [Iunit], and the horizontal axis represents the position in the width direction [mm]. In FIGS. 5A and 5B and FIGS. 7A and 7B, the width direction position 0 mm means the center in the width direction. In FIG. 5 to FIG. 7, “reference” means that the rolling load is a reference condition, and “−10%” means that the rolling load is reduced by 10% from the reference condition. Meaning “−20%” means that the rolling load is reduced by 20% from the reference condition, and “−30%” is the condition where the rolling load is reduced by 30% from the reference condition. Means that.

  Even when the rolling load is changed as shown in FIGS. 5 (a) and 5 (b), the rolling detected by the load cell of the rolling mill as shown in FIGS. 6 (a) and 6 (b). The load resulted in a similar result. On the other hand, as shown in FIGS. 7A and 7B, when the rolling load change mode is changed, the rolling shape changes. For example, when the rolling load is reduced by 30% from the reference condition, FIG. As shown in FIG. 7, in the sample having a difference in deformation resistance in the width direction, the end portion in the width direction changed to about 100 Iunits, and the deformation resistance was uniform in the width direction as shown in FIG. 7B. In this sample, the change was about 30 Inuit at the end in the width direction.

  FIG. 8 shows the relationship between the rolling load and the elongation difference at the end in the width direction on the exit side of each stand. In FIG. 8, “F1” is the result of the end in the width direction on the exit side of the stand arranged on the most upstream side in the plate passing direction among the five stands, and “F2” is from the upstream side in the plate passing direction. It is the result of the width direction end on the exit side of the stand arranged second, "F3" is the result of the width direction end on the exit side of the stand arranged third from the upstream side in the plate passing direction, “F4” is a result of the width direction end portion on the exit side of the stand arranged fourth from the upstream side in the plate passing direction, and “F5” is the exit side of the stand arranged on the most downstream side in the plate passing direction. It is a result of the width direction edge part in. In FIG. 8, the change behavior when the deformation resistance is uniform in the width direction is represented by a broken line, and the change behavior when the deformation resistance is not uniform in the width direction is represented by a solid line. As shown in FIG. 8, even when the deformation resistance is uniform in the width direction and when the deformation resistance is not uniform in the width direction, the elongation difference rate increases from a negative value to a positive value as the rolling load increases. Although it changes, the change behavior differs greatly depending on whether the deformation resistance is uniform in the width direction. From this result, the present inventors controlled the operation of the shape actuator of the rolling mill when the rolling load changed in order to keep the shape between the stands appropriate and ensure the stability of the plate. It has been found that it is effective to compensate for the amount of change in shape caused by fluctuations in rolling load. The variation in rolling load affects the shape because the deformation of the roll of the rolling mill changes and the distribution in the width direction of the upper and lower work roll gaps changes. Is caused by a deviation in the width direction. Since the roll of the rolling mill has a structure in which the left and right shaft end portions that do not contact the plate are supported by a bearing box, the roll is subjected to bending deformation due to a load acting during rolling. At the same time, the vicinity of the surface of the work roll in contact with the material to be rolled is subjected to flat deformation. In the setting up of the rolling mill, the roll deformation due to these loads is taken into consideration, and control is performed so that the roll gap distribution in the width direction becomes substantially uniform, and the shape of the material to be rolled is kept in a range that does not hinder the plate. In the above-described roll deformation, the bending deformation is a simple deformation form generally close to a parabola within the range of the diameter and axial length of the work roll of the cold tandem rolling mill which is the subject of the present invention. The influence of the distribution in the width direction of the load is small, and the influence of the total load is large. On the other hand, since the flat deformation of the work roll can be regarded as a dent deformation due to the pressure acting on the roll surface, the influence of the pressure distribution on the contact surface with the material to be rolled is large. For this reason, when a load fluctuation occurs under the condition that the deformation resistance in the width direction is substantially uniform, the influence of the bending deformation is dominant. On the other hand, when a difference in deformation resistance occurs in the width direction, the pressure between the material to be rolled and the work roll is high in the portion where the deformation resistance is large, and the pressure is low in the portion where the deformation resistance is small. Therefore, the flat deformation of the surface of the work roll is smaller in the portion where the deformation resistance is low and the deformation resistance is larger than that in the portion where the deformation resistance is large. The growth to Since this deformation is added to the deformation of the material to be rolled due to the bending deformation of the roll due to the total rolling load fluctuation, the above difference occurs. Here, as a change form of the deformation resistance of the material to be rolled, for example, four forms shown in Table 1 are assumed.

As shown in cases 1 and 2 of Table 1, when the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled, accompanying the change in the deformation resistance in the center portion in the width direction. The shape change becomes large. Therefore, when compensating for the amount of change in shape caused by fluctuations in rolling load, the change in load is caused by changes in the deformation resistance distribution in the width direction accompanying changes in the deformation resistance at the center in the width direction of the material to be rolled. In some cases, when changing the setting of the shape actuator than when compensating for the change in deformation resistance over the entire normal width or the change in shape caused by the load change caused by the change in the lubrication state caused by the change in rolling speed, etc. It is preferable to increase the amount of change. Conversely, when the deformation resistance of the width end portion is relatively small with respect to the width center portion, the shape of the width end portion is extended.
On the other hand, as shown in cases 3 and 4 of Table 1, the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled accompanying the change in the deformation resistance at the width direction end. In this case, since the direction of the shape change due to the influence of the total load (the shape change with the uniform deformation resistance) cancels out the direction of the shape change due to the influence of the deformation resistance distribution, the cases 1 and 2 in Table 1 are shown. The shape change is smaller than the case. Therefore, when compensating for the amount of change in shape due to fluctuations in rolling load, the change in load is caused by changes in the deformation resistance distribution in the width direction accompanying changes in the deformation resistance at the width direction end of the material to be rolled. In some cases, the load change is due to the change in the deformation resistance distribution in the width direction accompanying the change in the deformation resistance in the center in the width direction of the material to be rolled. It is preferable to reduce the amount of change.

  FIG. 9 shows the relationship between the case where the deformation resistance is uniform in the width direction and the case where the deformation resistance is not uniform and the elongation difference at the width direction end, and the calculated value of the shape control amount by the shape control actuator (bender, crown) control. Show. In FIG. 9, the result shown by the bar graph shows the relationship between the case where the deformation resistance in the width direction is uniform and the case where the deformation resistance is not uniform and the elongation difference at the end in the width direction, and the result shown by the line graph shows the shape control The result of the shape control amount by actuator control is shown. The vertical axis on the left side of FIG. 9 is the change in elongation [Iunit] at the end in the width direction compared to the center in the width direction under the condition where the rolling load is reduced by 20% from the reference condition, and the vertical axis on the right side of FIG. It is the shape control amount [Iunit] by the control actuator control.

  As shown in FIG. 9, in the first three stands (first to third stands: 4Hi rolling mill), the elongation difference rate when the deformation resistance in the width direction is uniform is more than the shape control amount by the vendor control. Since it is small, the shape change amount can be compensated only by the vendor control. On the other hand, in the former three stands, the elongation difference rate when the deformation resistance in the width direction is not uniform is larger than the shape control amount by the vendor control, and the vendor control and the crown control (roll cross angle, roll shift, etc. Smaller than the shape control amount by roll crown control). For this reason, when the deformation resistance in the width direction is not uniform, it is difficult to suppress the over-tension of the width direction end due to the middle elongation only by the vendor control, and the over tension at the width direction end due to the middle elongation is suppressed. To do this, it is necessary to perform crown control in addition to vendor control.

  In addition, as shown in FIG. 9, in the latter two stands (fourth stand and fifth stand: 6Hi rolling mill), even when the deformation resistance in the width direction is uniform, the deformation resistance in the width direction is uniform. Even if it is not, since the elongation difference rate is about the same as or smaller than the shape control amount by the vendor control, the shape change amount can be compensated only by the vendor control.

  The results shown in FIG. 9 are attributed to the fact that the amount of actuator control required to compensate for the shape change differs depending on whether or not the deformation resistance is uniform in the width direction and the change in the deformation resistance. Even if the shape after rolling in each stand changes, it is possible to compensate for the shape change by controlling the operation of the shape control actuator, and it is possible to suppress over tension at the end in the width direction. It is shown that.

  In addition, in the numerical simulation whose result is shown in FIG. 9, not only the difference in deformation resistance in the width direction but also the calculation is performed under the condition that the average value of the deformation resistance in the width direction changes greatly, and the change in the elongation difference rate is changed. The evaluation was made assuming the largest condition. However, it is unlikely that the average value of the deformation resistance in the width direction will change as much as the current numerical simulation in actual machine operation. Therefore, in actual operation, it is considered that in most cases, it is possible to compensate for the shape change within the control range of the shape control actuator.

  As described above, when the deformation resistance distribution in the width direction of the material to be rolled changes during rolling, the rolling shape changes greatly. As shown in FIGS. 6 (a) and 6 (b), it is difficult to properly predict a change in shape only by a change in rolling load detected by a load cell. In particular, a shape detection means (shape meter) is used. Between the intermediate stands that are not arranged (in the above-mentioned 5-stand tandem rolling mill, between the first stand and the second stand, between the second stand and the third stand, between the third stand and the fourth stand, And between the fourth stand and the fifth stand), the influence of the prediction error of the shape change is significant. The change in the rolling shape accompanying the change in the deformation resistance distribution of the material to be rolled is the final stand (the fifth stand in the example of the above-mentioned 5-stand tandem rolling mill) and the stand on the upstream side (the above-mentioned 5-stand tandem rolling). In the example of the machine, the first stand to the fourth stand) show substantially the same behavior. Therefore, when predicting a shape change between the intermediate stands due to a change in the deformation resistance distribution, it is effective to use a measurement result obtained by a shape meter arranged on the exit side of the final stand.

  FIG. 10 is a block diagram for explaining one embodiment of a method for cold rolling a metal plate according to the present invention. In the example shown in FIG. 10, a material to be rolled that has been rolled by a tandem rolling mill having stands 1, 2, 3, 4, and 5 is wound up by a tension reel 9, The deformation resistance distribution information X is input to the calculation control unit 8. The arithmetic control unit 8 uses the deformation resistance distribution information X to set the set value of the control target sent to the shape actuator control units 1a, 2a, 3a, 4a, and 5a of the respective stands 1, 2, 3, 4, and 5. A setup calculation for determination is performed, and the set value of the control target determined by the calculation control unit 8 is sent to the shape actuator control units 1a, 2a, 3a, 4a, and 5a. During cold rolling, the shape measurement result measured by the shape meter 6 disposed on the exit side of the final stand 5 is input to the arithmetic control unit 8 via the shape signal processing unit 7. In addition, a rolling load signal measured by the load cells 1 b, 2 b, 3 b, 4 b, 5 b of each stand 1, 2, 3, 4, 5 is also sent to the calculation control unit 8. The arithmetic control unit 8 is based on the difference between the shape measurement value sent via the shape signal processing unit 7 and the shape prediction value calculated on the assumption that the deformation resistance in the width direction of the material to be rolled is uniform. Thus, the deformation resistance distribution in the width direction of the material to be rolled is estimated. At the same time, when the rolling load measured by the load cells 1b, 2b, 3b, 4b and 5b changes, the deformation resistance distribution in the width direction is obtained using the shape measurement value sent via the shape signal processing unit 7. The change amount of the rolling load due to the change is calculated, and the control target value change amount to the shape actuator control units 1a, 2a, 3a, 4a, 5a is calculated using this, and the shape actuator control units 1a, 2a, 3a are calculated. 4a and 5a are instructed with the changed control target value. In the example shown in FIG. 10, the metal plate which prevented the plate troubles, such as plate breakage in rolling, at low cost by operating the stands 1, 2, 3, 4, 5 based on the control target value after the change. Is cold rolled. According to the present invention, since the operation of the rolling mill can be appropriately controlled according to the deformation resistance of the metal plate, the present invention can be suitably implemented when manufacturing high-tensile steel or the like.

Occurrence of plate troubles such as plate breakage and narrowing when the control shown in FIG. 10 is applied (Example 1 of the present invention, Example 2 of the present invention) and when the present invention is not applied (Comparative Example 1). The result of verifying the rate is shown in FIG.
Example 1 of the present invention is a result when the deformation resistance distribution in the width direction of the material to be rolled is specified in advance, and the specified result is applied only to the setup calculation of the rolling mill (shape control actuator). In addition to Example 1 of the present invention, the deformation resistance distribution in the width direction of the material to be rolled on the entry side of the rolling mill is estimated using the shape measurement result of the material to be rolled by a shape meter, and the shape is determined using this estimation result. This is a result when the setting of the control actuator is changed.

  As shown in FIG. 11, compared with Comparative Example 1, Example 1 of the present invention reduces the occurrence ratio of the plate-passing trouble to about ½, and Example 2 of the present invention is Example 1 of the present invention. In comparison, the rate of occurrence of sheeting troubles was reduced to about 1/2. From this result, even when the material to be rolled having a variation in deformation resistance in the width direction is cold-rolled, according to the present invention, the influence of the difference in deformation resistance in the width direction of the material to be rolled can be reduced, It was confirmed that plate troubles such as plate breakage and narrowing can be reduced.

  In addition, when the change in rolling load is caused by the change in deformation resistance distribution in the width direction of the material to be rolled due to the change in deformation resistance in the center in the width direction of the material to be rolled, the change in rolling load is subject to change. Sheet when cold rolling is performed while increasing the amount of change in the setting value of the shape control actuator of the rolling mill (invention example 3), compared to the case where it does not result from a change in the deformation resistance distribution in the width direction of the rolled material. FIG. 12 shows the results of verifying the occurrence rate of plate troubles such as breakage and narrowing. Moreover, even if the change in rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center in the width direction of the material to be rolled, When cold rolling is performed while changing the set value of the shape control actuator within the range of the change amount of the set value of the shape control actuator or less when the change is not caused by the change in the deformation resistance distribution in the width direction of the material to be rolled FIG. 12 also shows the results of verifying the rate of occurrence of plate troubles such as plate breakage and narrowing in (Comparative Example 2).

  As shown in FIG. 12, compared with Comparative Example 2, Example 3 of the present invention reduced the occurrence ratio of the plate passing trouble to about ½. As a result, when the change in the rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center in the width direction of the material to be rolled, the change in the rolling load is According to the present invention in which cold rolling is performed while increasing the amount of change in the setting value of the shape control actuator of the rolling mill, compared to the case where it does not result from a change in the deformation resistance distribution in the width direction of the material to be rolled, It was confirmed that the trouble of passing through such as narrowing can be reduced.

X ... Deformation resistance distribution information in the width direction of the material to be rolled 1, 2, 3, 4, 5 ... Stand (rolling mill)
DESCRIPTION OF SYMBOLS 1a, 2a, 3a, 4a, 5a ... Shape actuator control part 1b, 2b, 3b, 4b, 5b ... Load cell 6 ... Shape meter 7 ... Shape signal processing part 8 ... Calculation control part 9 ... Tension reel

Claims (5)

The difference between the shape of the rolled material measured on the exit side of the rolling mill during the cold rolling and the predicted shape of the rolled material obtained from the rolling conditions of the rolling mill, and previously determined Using the deformation resistance distribution information in the width direction of the material to be rolled, to estimate the deformation resistance distribution in the width direction of the material to be rolled on the upstream side of the rolling mill,
When the deformation resistance of the end portion in the width direction of the rolled material is higher than the deformation resistance of the widthwise central portion, by using the rolling mill is set to be the ear wave shape, wherein the material to be rolled cold-rolled And
When the deformation resistance of the end portion in the width direction of the rolled material is less than the deformation resistance of the widthwise central portion, by using the rolling mill is set to be middle elongation shape, the material to be rolled and cold rolled A method for cold rolling a metal plate. For the material to be rolled, the deformation resistance distribution in the width direction is specified in advance,
When the specified deformation resistance at the end in the width direction is higher than the deformation resistance at the center in the width direction, the set value of the shape control actuator of the rolling mill is equal to the deformation resistance of the material to be rolled in the width direction. With a setting value that is an ear wave shape than the setting value derived from the setup calculation that is assumed to be, the material to be rolled is cold-rolled,
When the specified deformation resistance at the end in the width direction is lower than the deformation resistance at the center in the width direction, the set value of the shape control actuator of the rolling mill is stretched more than the set value derived from the setup calculation. The cold rolling method of the metal plate according to claim 1, wherein the material to be rolled is cold-rolled with a set value to be a shape. During the cold rolling, the rolling load applied from the rolling mill to the material to be rolled is measured, and the setting of the shape control actuator of the rolling mill is changed according to the measured change in the rolling load.
When the change in the rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center in the width direction of the material to be rolled, The cold rolling of the metal plate according to claim 1 or 2, wherein the amount of change in the set value of the shape control actuator is larger than when the change is not caused by a change in the deformation resistance distribution in the width direction of the material to be rolled. Method. During the cold rolling, the rolling load applied from the rolling mill to the material to be rolled is measured, and the setting of the shape control actuator of the rolling mill is changed according to the measured change in the rolling load.
When the change in the rolling load is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance of the width direction end of the material to be rolled, The change in the set value of the shape control actuator is more than the case where the change is caused by the change in the deformation resistance distribution in the width direction of the material to be rolled due to the change in the deformation resistance in the center portion in the width direction of the material to be rolled. The method for cold rolling a metal plate according to claim 1 or 2, wherein the amount of change is reduced. The manufacturing method of a metal plate which has the process of cold-rolling a metal plate using the cold-rolling method of the metal plate of any one of Claims 1-4 .