JP2006075882A - Method for controlling thickness of sheet in cold tandem mill and method for manufacturing cold-rolled metallic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To bring the sheet thickness of a material to be rolled close to the target value uniformly over the entire length as much as possible even in the case that the output of sheet thickness control is saturated so that the output of automatic gauge control (AGC) is kept to the limit. <P>SOLUTION: When the output of the sheet thickness control at the i-th stand is saturated, the output of the sheet thickness control at the i-th stand is made so as not to be saturated by changing the target value of the sheet thickness at least at the (i-1)th stand among the stands on the side of the preceding stage of the i-th stand. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for controlling the thickness of a cold tandem rolling mill used for manufacturing a cold-rolled metal plate (including a cold-rolled metal strip) such as a cold-rolled steel plate, and a method for manufacturing a cold-rolled metal plate using the same. Is.

  A cold tandem rolling mill connected with multiple rolling mills (stands) that cold-rolls a metal sheet such as a wide strip steel manufactured through hot rolling at room temperature to produce a metal sheet such as a cold-rolled steel sheet. For the purpose of control, automatic sheet thickness control (hereinafter referred to as AGC) is applied for the purpose of bringing the sheet thickness of the product metal plate as close as possible to the target value.

  In addition, automatic tension control (hereinafter referred to as ATC) is also applied for the purpose of stable operation by suppressing the tension acting on the metal sheet to be rolled to below the tensile strength during rolling and preventing breakage. Has been.

  By appropriately adjusting the two target values of plate thickness and tension, the rotation speed of the work rolls of each rolling mill (stand) and the gap between the upper and lower work rolls (interval between the upper and lower work rolls) Two controls, automatic plate thickness control and automatic tension control, can be performed simultaneously.

  FIG. 4 shows a part of a conventional cold tandem rolling mill. In FIG. 4, the work roll 1 is driven by an upper and lower electric motor 3, and the electric motor 3 can be adjusted in rotational speed by a control device 10.

  The gap between the upper and lower work rolls can be adjusted by a reduction device 8 driven by hydraulic pressure or an electric motor.

  Incidentally, in FIG. 4, 2 is a backup roll, 4 is a tension detector, and 6 is a thickness gauge. Based on the output of the tension detector 4 and the thickness gauge 6, the automatic thickness control (AGC) described above Automatic tension control (ATC) is performed. Reference numeral 20 denotes a calculator, which performs various calculations such as a gap between the upper and lower work rolls of each stand and a target value such as a work roll rotation speed at the tip of each rolled material.

  As a metal material manufactured by such a cold tandem rolling mill, a cold-rolled steel sheet (including a steel strip) defined in JISG3141 is representative, and in addition to a tin plate original sheet defined in JISG3303, an aluminum plate Copper plates and the like are also manufactured. The cold-rolled metal plate referred to in the present invention is a generic term for these.

  Automatic plate thickness control (AGC) can be broadly divided into the speed AGC that adjusts the tension by adjusting the difference between the rotation speeds of the work rolls of two adjacent stands, and consequently the plate thickness. There are two reduction AGCs that adjust the gap between work rolls.

  On the other hand, in automatic tension control, the gap between the work roll and the speed ATR (Automatic Tension Regulator) that adjusts the tension between the two stands is adjusted by adjusting the difference between the rotation speeds of the work rolls of two adjacent stands. There are two reduction ATRs that adjust the tension between the two stands.

  When automatic plate thickness control (AGC) and automatic tension control (ATC) are actually applied to a cold tandem rolling mill at the same time, automatic The speed AGC is applied as the plate thickness control, and the automatic tension control is generally applied by a so-called dead zone ATR having an upper and lower limit in the control output or a speed ATR having a dead zone.

  In the control of the thickness of the cold tandem rolling mill, by adjusting the gap between the upper and lower work rolls at the first stand, first, make the exit side thickness of the first stand as uniform as possible to the target value. Control to approach. For example, when the exit side plate thickness of the first stand is thicker than the target value, the exit side plate thickness of the first stand is brought closer to the target value by adjusting the reduction (gap between the upper and lower work rolls) in the closing direction. Is possible.

  In addition, for the outlet side plate thickness of the i-th stand downstream from the first stand, the outlet side plate thickness of the i-th stand is set to the target value by adjusting the rotation speed of the work roll of the preceding i-th stand. Control so that the overall length is as close as possible. For example, when the exit side plate thickness of the i-th stand is thicker than the target value, the exit side plate thickness of the i-th stand is set to the target value by adjusting the rotation speed of the work roll of the i-th stand. It becomes possible to approach.

  For example, Patent Literature 1, Patent Literature 2, Patent Literature 3 and the like can be cited as prior art relating to sheet thickness control of a cold tandem rolling mill.

  Next, the tension control between each stand of the cold tandem rolling mill is common to each stand. For example, when the tension of the material to be rolled between the i-th stand and the i-th stand is higher than the target value. It is possible to approach the target value by adjusting the gap between the upper and lower work rolls of the i-th stand in the closing direction, and to adjust the work roll speed of the i-th stand to be accelerated. This also makes it possible to approach the target value.

  As a prior art regarding tension control of a cold tandem rolling mill, for example, Patent Literature 4 can be cited.

  As described above, the speed AGC, which is generally controlled by adjusting the rotation speed of the work roll of the i-1th stand, is applied to the plate thickness control of the conventional cold tandem rolling mill. At that time, in order to control the thickness of the conventional cold tandem rolling mill, a thickness gauge is installed on the outlet side of the i-th stand, and the work of the i-1th stand is based on the thickness measured by the thickness gauge. The rotation speed of the roll was determined.

  In cold rolling of cold-rolled steel sheets using conventional cold tandem rolling mills, the material to be actually rolled (wide strip steel produced through hot rolling: hot-rolled steel sheet) is used as the cold tandem. Before starting cold rolling using a rolling mill, for each steel type and product size category, the leading end of each material to be rolled and the target value of the exit side plate thickness of each stand in the above-described computer 20 Calculate the predicted value of the rolling load at each stand and the target value of the tension between the stands, and set these target values at the timing when cold rolling of the target material to be rolled starts. By adjusting the reduction of each stand (gap between the upper and lower work rolls) and the rotation speed of the work rolls so as to meet the target values, the thickness of the tip of each rolled material can be made as much as possible. I tried to get closer to the target value.

  However, since the target values of the reduction (gap between the upper and lower work rolls) and the work roll rotation speed are obtained from the calculation formulas, the reduction (gap between the upper and lower work rolls) and the work roll rotation speed are set. Therefore, the target value of the outlet side plate thickness of each stand, the predicted value of the rolling load at each stand, and the target value of the tension between the stands are not always met. Therefore, automatic plate thickness control (AGC) and automatic tension control (ATC) as described above are performed, and the plate thickness is made as close as possible to each target value behind the tip of the material to be rolled. is there.

Japanese Patent Application Laid-Open No. 08-057509 JP 09-057317 A JP 61-162221 A JP-A-56-117816

  Setting the target value of the exit side plate thickness of each stand, the target value of the tension between each stand, etc. at the tip of each material to be rolled is called the initial setting, depending on the steel type, product dimensions, or other rolling conditions. The plate thickness does not match the initial setting, and in some cases, this may greatly deviate from the initial setting. Then, in such a case, a very large value is about to be determined as the output of the reduction by automatic sheet thickness control (AGC) or the change amount of the rotation speed of the work roll, behind the tip of the material to be rolled.

  However, conventionally, the output of automatic sheet thickness control (AGC) is about 10% of each target value ± each target value for both the reduction (gap between the upper and lower work rolls) and the rotation speed of the work roll with respect to the initial setting. A limit is applied so that the output outside the range is not determined. A range of about 10% of each target value ± each target value that has appeared here is generally referred to as a control range.

  Then, when the plate thickness is large and deviates from the initial setting, the output may stick to the limit over part or all of the entire length of the material to be rolled.

  In this way, the sheet thickness control output is saturated that the output of automatic sheet thickness control (AGC) such as the reduction (gap between the upper and lower work rolls) and the rotation speed of the work roll sticks to the limit. However, if the plate thickness control output is saturated, the plate thickness control output that falls outside the control range cannot be output. As a result, a significant portion of the total thickness of the material to be rolled is There is a range, but even that) is out of question, which is a problem.

  In the present invention, even when a situation occurs in which the sheet thickness control output is saturated, the output of such automatic sheet thickness control (AGC) sticks to the limit, the sheet is rearward from the tip of the material to be rolled. It is an object to make the thickness as close as possible to each target value, thereby making the plate thickness of the material to be rolled as close as possible to the target value as uniformly as possible.

  In the thickness control method of a cold tandem rolling mill, when the thickness control output of the i-th stand is saturated, the present invention provides at least the thickness of the i-1 stand among the stands preceding the i-th stand. A thickness control method for a cold tandem rolling mill, characterized in that the target value is changed so that the thickness control output of the i-th stand is not saturated.

  Moreover, this invention is a manufacturing method of the cold-rolled metal plate characterized by using the plate | board thickness control method of the cold tandem rolling mill.

  According to the present invention, even when a situation occurs in which the output of automatic sheet thickness control (AGC) sticks to the limit and the sheet thickness control output is saturated, the sheet thickness is rearward from the tip of the material to be rolled. As close as possible to each target value, the thickness of the material to be rolled can be made as close to the target value as uniform as possible over the entire length.

  Hereinafter, an embodiment of a sheet thickness control method for a cold tandem rolling mill according to the present invention will be described with reference to the drawings as appropriate.

  FIG. 1 is a schematic configuration diagram showing a part of a 5-stand cold tandem rolling mill according to an embodiment of the present invention.

  This cold tandem rolling mill basically follows the conventional cold tandem rolling mill shown in FIG. 4 and limits the number of stands to five. A work roll 1, a backup roll 2, an electric motor 3, a tension detector 4, a thickness gauge 6, a reduction device 8, a control device 10, a computer 20, and the like are also used as they are.

  The thickness gauge 6 may be installed not only at the final stand exit side of the cold tandem rolling mill but also at one or more places between the stands, which is one less than the number of stands, and the first stand is inserted. It can be installed on the side. The thickness on the stand exit side where the thickness gauge 6 is not installed is roughly determined by the controller 10 or the computer 20 based on the rolling load at the last stand and the gap between the upper and lower work rolls. Is divided by the plate thickness calculated in real time so as to add the gap between the upper and lower work rolls by dividing by the rigidity of the rolling mill. The plate thickness on the entry side of the first stand may be substituted by the finish plate thickness in hot rolling which is the previous step.

  As described above, there are two types of automatic plate thickness control (AGC): speed AGC and reduction AGC. Both cases will be described below.

  For both speed AGC and reduction AGC, if the intended stand is now the i-th stand, the rolling load of the i-th stand (by the output of a load meter provided in the reduction device 8) is input. Or input the tension of the material to be rolled between the i-th stand and the preceding i-th stand, or input the exit side plate thickness of the i-th stand, or two of them The above is combined or input. If only one or two are used, the control gain that is not used may be set to zero. (Here, for simplicity, when the tension of the material to be rolled between the i-th stand and the i-th stand is used as an input, and when the exit side plate thickness of the i-th stand is used as an input, A case where the tension of the material to be rolled between the i-th stand and the i + 1-th stand is used as an input, or a case where an input side plate thickness of the i-th stand is used as an input can be assumed, and these cases also fall within the scope of the present invention. )

  Now, if rolling of the material to be rolled is continued, the rolling load of the i-th stand may increase or decrease, and the tension of the material to be rolled between the i-th stand and the i-1th stand may also increase or decrease. In addition, the thickness of the outlet side plate of the i-th stand may increase or decrease.

  Both the speed AGC and the reduction AGC are initially controlled as described below. FIG. 2 shows an outline of a control block diagram in each case of (a) speed AGC and (b) reduction AGC.

  When the rolling load of the i-th stand is input and when the tension of the material to be rolled between the i-th stand and the i-1 stand is input, the maximum load such as the joint portion of the target material to be rolled is used. When rolling up to the tip (excluding several meters in the transport direction from the tip) excluding the tip, the rolling load of the i-th stand at that time, the tension of the material to be rolled between the i-th stand and the i-1 stand Is locked on (stored as a representative value), and an appropriate gain is obtained for each deviation from the rolling load of the i-th stand that is locked on and the tension of the material to be rolled between the i-th stand and the i-th stand. In the case of the speed AGC, the rotational speed of the work roll of the i-1th stand is adjusted, and in the case of the reduction AGC, the gap between the upper and lower work rolls of the ith stand is adjusted.

  When the exit side thickness of the i-th stand is used as an input, the deviation between the target value and the actual value of the exit side thickness of the i-th stand as data in the control device 10 or the computer 20 is multiplied by an appropriate gain, and the speed In the case of AGC, the rotational speed of the work roll of the i-th stand is adjusted, and in the case of rolling AGC, the gap between the upper and lower work rolls of the i-th stand is adjusted.

  In the case of the speed AGC, if the rolling load of the i-th stand increases or if the tension of the material to be rolled between the i-th stand and the i-1 stand increases, the rotation of the work roll of the i-1 stand If the speed is increased and the rolling load of the i-th stand decreases, or if the tension of the material to be rolled between the i-th stand and the i-1 stand decreases, the work roll of the i-1 stand rotates. Decrease speed.

  In the case of reduced AGC, if the rolling load of the i-th stand increases or if the tension of the material to be rolled between the i-th stand and the i-1 stand increases, the gap between the upper and lower work rolls of the i-th stand If the rolling load of the i-th stand decreases or the tension of the material to be rolled between the i-th stand and the i-th stand decreases, the gap between the upper and lower work rolls of the i-th stand is widened.

  The final output has a structure in which a limit 9 is applied, and a control range is provided.

  In the present invention, when the plate thickness control output of the i-th stand (which can be output in either case of speed AGC or reduction AGC) is saturated (becomes a limit) and the control range is exceeded, The point is to correct the thickness of the entry side so that the thickness control of the i-th stand is within the aforementioned control range.

  At that time, if only the exit side plate thickness of the i-1th stand is corrected, the balance of the volume speed (mass flow) of the rolled material as the whole cold tandem rolling mill is lost, and the rolled material is broken or bulged. In the present invention, in consideration of such points, the cold tandem rolling mill as a whole is rolled. From the viewpoint of preferably keeping the balance of the volume velocity (mass flow) of the material as close as possible to the target value of the outlet side plate thickness of the i-th stand, the incoming side plate thickness (i-th- In correcting the outlet thickness of one stand), it is preferable to change the target value of the outlet thickness of the stand preceding the i-1th stand.

  As a result of the change, it is assumed that the change is performed within a limit that does not deviate from the control range of the plate thickness control in each of the change target stands before the i-th stand.

  The sheet thickness control method of the cold tandem rolling mill of the present invention starts when the sheet thickness control output of the i-th stand is saturated and ends when the saturation of the sheet thickness control output of the i-th stand is eliminated.

  The point in time at which the saturation of the thickness control output of the i-th stand is eliminated refers to, for example, the point in time when the plate thickness control output enters about ½ of the control range. It is preferable that it can be changed as appropriate.

  The plate thickness control method of the cold tandem rolling mill of the present invention was applied to a cold tandem rolling mill consisting of 5 stands.

  The result is shown in FIG. In the state where the thickness of the tip of the material to be rolled at the exit side of the fifth stand, which is the final stand, is greatly deviated to the plus side with respect to the initial setting, the thickness control output is originally sent to the final stand. Control output is output to the side where the outlet side thickness of the fifth stand is to be reduced by increasing the tension by reducing the work roll rotation speed for the adjacent fourth stand on the upstream side. 10% of the time, and out of the control range.

  Therefore, in this example, the target value of the outlet side plate thickness of all the first to fourth stands is decreased. In this case, in this example, first, each of the stands has a rate of change with respect to a certain time, and F1> F2> F3> F4 (Fn indicates the nth stand) in the order of F1> F2> F3> F4. While increasing the amount by which the target value of the outlet side plate thickness is reduced and maintaining the ratio of the amount to reduce the target value of the outlet side plate thickness between the stands constant, the outlet side plate thickness of each stand is changed over time. I am trying to change it. As a result, the overall thickness of the fifth stand can be as close as possible to the target value so as to be within the allowable range.

  Then, contrary to the case where the exit side plate thickness of the fifth stand is greatly deviated to the plus side with respect to the initial setting, when it deviates to the minus side, the plate thickness control output is output in the opposite direction, When the output becomes -5% which is half of the limit value, the sheet thickness control method of the cold tandem rolling mill of the present invention is stopped, and the original automatic sheet thickness control (AGC) is restored. In this way, in subsequent automatic plate thickness control (AGC), plate thickness control output is possible in both positive and negative directions with respect to the target value of the outlet side plate thickness of the fifth stand, and stable plate thickness control is possible. It becomes possible.

  As described above, the above-described embodiment is merely an example, and the embodiment of the present invention is not limited thereto. That is, various changes can be made.

  For example, as a material to be rolled, not only a cold-rolled steel sheet but also various cold-rolled metal sheets can be targeted, and the cold tandem rolling mill is not limited to a 5-stand type, and any material can be used as long as it has multiple stands. The number of stands may be used.

  Further, in the above embodiment, in the 5-stand cold tandem rolling mill, the application stand, i.e., the i-th stand is the fifth stand, and the exit side plate thicknesses of all the first to fourth stands before the fifth stand are set. However, the application stand may be a stand other than the fifth stand, and the target value of the outlet side thickness may be changed not only for all the stands on the front side of the i-th stand. Only the stands of the stands may be changed, and the rate of change with time is not necessarily constant, and the amount of change of the target value of the exit side plate thickness of each stand is increased in the order of F1> F2> F3> F4. It is not necessary to limit to the case, and it is not necessary to maintain a constant ratio between each stand for changing the target value of the delivery side thickness, and the volume speed of the material to be rolled as the whole cold tandem rolling mill. Collapsed balance (mass flow) is, or trouble on passing plate as breaking Yada first time of the material to be rolled, the extent there is no risk of causing trouble on the product quality such as heat streaks, can freely adjust.

  According to the present invention, it is possible to ensure good product dimensional accuracy when cold-rolling various metal plates such as stainless steel plate, aluminum plate, copper plate, etc. in addition to general steel. Have.

The schematic block diagram which shows a part of 5-stand cold tandem rolling mill which is one Embodiment of this invention Schematic block diagram of control of one embodiment of the present invention The figure which shows the result of application of one Embodiment of this invention Schematic showing a part of a conventional cold tandem rolling mill

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Work roll 2 ... Backup roll 3 ... Electric motor 4 ... Tension detector 8 ... Reduction device 9 ... Limit 10 ... Control device 20 ... Computer

Claims (2)

In the sheet thickness control method of the cold tandem rolling mill,
When the plate thickness control output of the i-th stand is saturated, the plate thickness control output of the i-th stand is changed by changing the plate thickness target value of at least the i-1 stand among the stands upstream from the first stand. A method for controlling the thickness of a cold tandem rolling mill characterized by preventing saturation.   A method for producing a cold-rolled metal sheet, wherein the sheet thickness control method for a cold tandem rolling mill according to claim 1 is used.

Images