JPH0833908A - Method for correcting setup at time of passing in continuous rolling - Google Patents

Abstract

PURPOSE:To provide the method which enables correction of setup errors in downstream stands simply and with high precision and which also excels in implementability. CONSTITUTION:A non-thickness error element is estimated from the load and thickness record of an (i) stand; a setup is done by performing the load correction of i+1 stand based on the estimate; a gauge meter error is estimated from the record of the load/thickness of the i+1 stand; the gauge meter thickness is corrected, based on this estimated result, at the entrance and exit side of the i+1 stand which is a thickness error element; and, by using this corrected value, the non-thickness error element is reestimated and corrected. Then, the load of the i+2 stand is predicted by using the corrected error elements in thickness and non-thickness; and also, the roll gap value of the i+2 stand is corrected based on the predicted load and the corrected gauge meter formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the thickness of a metal strip when it is continuously rolled into a strip or a strip, and particularly to a roll gap setup correction at the time of stripping, which is related to the accuracy of the tip. Regarding the method.

[0002]

2. Description of the Related Art In a rolling mill in which a rolled material made of a metal material is continuously rolled by passing it through rolling rolls provided on a plurality of stands, in order to achieve a target value of thickness immediately after the rolling, the roll is rolled in advance. A setup function is provided to calculate the optimum value of the gap and then set the gap of the rolling rolls provided in each stand.

When the roll gap is set up, if the optimum roll gap is correctly obtained from the beginning, a product with excellent plate thickness accuracy can be obtained from the tip of the rolled material, but there is an error in the roll gap. In such a case, a portion where the plate thickness deviates from the tolerance occurs at the tip of the rolled material before the gap adjustment by the plate thickness feedback control is completed. Since this part of the rolled material cannot be used as a product, its length must be shortened in order to improve the yield. Therefore, setup accuracy is one of the important technical issues. Normally, the roll gap value is calculated after calculating the predicted load during rolling.
It is determined by the following gauge meter formula so that the target outlet plate thickness can be obtained.

[0004]

[Equation 1]

H: Outgoing plate thickness So: Roll gap P: Rolling load K: Mill rigidity coefficient (spring constant of rolling mill) GMC: Gauge meter correction constant (correction of actual gap variation due to roll temperature rise, etc.) Of these, K Is a value specific to the rolling mill and is known in advance. GMC is mainly affected by thermal expansion of rolls. Since this value changes gradually, sufficient accuracy can be obtained even if the calculation result of the previous rolling results is used for prediction of the current rolling. Then, P can be generally calculated by the following formula.

[0006]

[Equation 2]

P: Rolling load km: Average deformation resistance (function of material and temperature) B: Strip width H: Inlet strip thickness (H-h): Reduction amount R ': Flat roll radius (P, B, H-h) , Function of roll rigidity) Qp: Rolling force function (functions of friction between roll and plate, H, h, km, tension, etc.) That is, from the process plan and product specifications, the inlet / outlet plate thickness, plate width, tension, material, etc. Once determined, the setup gap setting value is determined from the actual values of the coefficient of friction between the roll and the rolled material and the plate temperature, using the equations (1) and (2). Among them, the plate thickness and the plate temperature change for each rolling, but the friction coefficient is determined by the roll surface condition, the lubrication condition, etc., and gradually changes by repeating the rolling.

Therefore, in the actual setup calculation, the plate thickness and plate temperature on the entrance side are measured on the entrance table immediately before rolling, and the friction coefficient is calculated based on the results up to the previous rolling.

However, there is a measurement error in the plate thickness and plate temperature of the rolled material, which causes an error in the setup. In addition, even if the same material is used, if the added components are varied, the deformation resistance varies from rolling to rolling, but this cannot be corrected at the time of setup before passing.

Further, in the tandem mill, the error in the plate thickness on the outlet side of the upstream stand becomes the error on the plate thickness on the inlet side of the next stand, which causes an error in the setup gap, but this cannot be corrected before passing the plate.

From the above, in continuous rolling, the setup error of the roll gap of the downstream stand can be corrected easily and with high accuracy by removing the influence of the setup error of the roll roll before the stripping is inevitable. There is a demand for realization of a possible method.

[0012]

In order to solve this problem, the actual rolling value of the upstream stand (passage side plate thickness, load, etc.) during passing
From the above, it is possible to improve by calculating the setup error and sequentially correcting the roll gap of each stand until the rolled material is caught in the downstream side stand.

As a known technique based on this idea, for example, Japanese Patent Application Laid-Open No. 03-32411 discloses "Dynamic Setup Method for Rolling Mill". In this method, the load factor of the two upstream stands is used to separate the error factors and correct the preset gap in the latter stage.

However, the two main factors of the load error are listed, but they are not individually evaluated separately, and the roll gap correction law itself is a regression equation completely unrelated to the original gauge meter equation. There is little basis for the fact that ambiguity is introduced and the accuracy of the product sheet thickness is improved compared to the conventional technology, and the inventive step is questionable.

Further, Japanese Unexamined Patent Publication No. 60-99410 discloses "an adaptive setting method in hot strip rolling". This method employs a method in which the setup error is separated into a friction factor and a deformation resistance factor based on the actual load results and the advanced ratio actual results of the first stand, and the individual corrections are made. This is for the reason described below.

That is, the friction between the rolled material and the roll is influenced by the roll surface state and the lubrication state, and is an independent factor for the stand. The same factor for each downstream stand is completely different. Therefore, when the correction of the downstream stand is performed based on the actual results of the first stand without removing the friction factor, the reverse effect is often generated.

However, in general, the friction factor does not significantly change between the previous rolling and the current rolling even if the type of material changes. In this case, a general method called so-called learning in which an error correction coefficient obtained from the difference between the setup and the actual result is used for the setup of the next rolling is effective. Therefore, if this function operates normally, it is considered that the actual factor error of the first stand hardly includes the friction factor.

In reality, a programmable controller or the like is often used to realize the above setup correction control, but in a short time from the biting of one stand to the biting of the next stand, a considerable amount of time is required. Considering that complicated processing needs to be executed, the method should be as simple as possible in terms of feasibility.

Further, a plate thickness gauge is indispensably provided on the exit side of the first stand, but it is difficult to install the plate thickness gauge in lubrication rolling, and a new cost burden is required for installation and maintenance. To do. Further, since the deformation resistance calculation formula correction and the gauge meter constant correction are limited to only the first stand, it is difficult to achieve a sufficient effect due to the difference between the stands in a multi-high rolling mill train having 6 to 7 stands. Is concerned.

The present invention has been made based on the above-mentioned circumstances, and it becomes possible to easily and accurately compensate for the setup error of the downstream stand, and it is possible to correct the setup at the time of strip passing in continuous rolling which is excellent in practicability. The purpose is to provide a method.

[0021]

Since the gap setup accuracy is mainly due to a load prediction error, its factor will be examined. The parameters that affect each item in the above equation (2) are summarized in Table 1. Table 1 shows the magnitude of the error that can occur during the setup calculation and the degree of influence of the error on the rolling load prediction in consideration of the actual rolling process. In Table 1, the fact that setup is possible means that the setup side is sufficient because sufficient accuracy can be obtained by conventional techniques such as learning and actual measurement before rolling. Then, it was evaluated that items that are greatly affected by parameters that cannot be set up have a large influence on the load error.

[0022]

[Table 1]

* Indicates the case where the front-stage delivery side plate thickness deviates from the target value after the second stand. It can be measured at the first stand. ** If you actually measure it before rolling, the change between stands will be small, so it can be handled by the setup calculation.

*** The tension is controlled to a value determined by the setup. It can be seen from Table 1 that the unavoidable error factors for the setup calculation before rolling are the portions affected by the deformation resistance, the reduction amount, and the reduction force function, such as the plate thickness. On the other hand, in general, the error of the friction coefficient is
It is considered to be an important parameter because it affects the error of the rolling force function most, but it was decided not to consider it because sufficient accuracy can be obtained by setup.

Therefore, the factors that require compensation at the time of passing the sheet are mainly related to deformation resistance such as temperature and material except for the factors of plate thickness error, and the rolling force function is also a slight error factor. These deformation resistance-related and rolling force functions are non-thickness error factors.

Since these factors are common to each stand, if one error evaluation coefficient is considered, the value can be obtained from the rolling record of a certain stand and used for the rolling load prediction correction of the downstream stand.

As a result of the above examination, it becomes possible to easily and highly accurately compensate for the setup error of the downstream stand, and it becomes possible to obtain a method with excellent feasibility. That is, the feasibility is enhanced by reducing the number of sensors and arithmetic processing and making it less susceptible to equipment restrictions.

The present invention is based on such an idea. That is, the setup correction method during strip passing in the continuous rolling of the present invention, when continuously rolling the rolled material made of a metal material through the rolling stand provided in each of the plurality of stands, before the sheet passing, After setting up the roll gap of the rolling roll, calculate the setup error of the stand downstream from that stand based on the rolling record of a specific stand during passing, and roll the roll before it reaches the next stand. A method of correcting a gap, which is optional i
The non-thickness error factor is estimated from the load and the actual thickness of the stand, the load of the i + 1 stand is corrected and set up based on this estimation result, and the gauge meter error is estimated from the actual load and the actual thickness of the i + 1 stand. Based on the result of this estimation, the gauge thickness of the gauge meter on the inlet side and the outlet side of the i + 1 stand, which is a factor of plate thickness error, is corrected, and the non-plate thickness error factor is re-estimated and corrected using this corrected value. The load of the i + 2 stand is predicted by using the corrected plate thickness error factor and the non-plate thickness error factor, and the roll gap value of the i + 2 stand is corrected based on the predicted load and the corrected gauge meter formula. And

[0029]

The operation of the method of the present invention will be described. From the above formula (2), the preset prediction values of km, B, R ', h, and Qp are set to km ^* , B ^* , R' ^* , h ^* , and Qp ^* , of which B; plate width, R '; Assuming that the flat roll radius has sufficient setup accuracy, B = B ^* , R ′ =
Since it can be regarded as R ' ^* , the actual load value; P and the predicted value; P
The ratio with ^* is as follows.

[0030]

(Equation 3) Here, the deformation resistance / rolling force function correction coefficient between one calculation and one achievement is defined as follows.

[0031]

[Equation 4]

This C _KQ does not include an independent error factor for each stand. Therefore, the value is common to all stands. Expressed using a subscript indicating the stand number,
From equations (3) and (4),

[0033]

(Equation 5) Becomes

The coefficient C _KQ , which is the non-thickness error factor error, is calculated from equation (5) from the actual load at the time of biting the rolled material at a certain upstream stand i, the outgoing side plate thickness, and each setup value, and that stand is calculated. Assuming that the output side plate thickness of No. 2 is the input side plate thickness of the next stand and the output side plate thickness of the next stand is the plate thickness target value, the setup load can be corrected by applying the following formula of the next stand.

[0035]

(Equation 6)

By the way, in the equation (6), when the gauge meter plate thickness h _ig obtained by applying the actual load and the actual gap of the i stand to the gauge meter plate thickness h _i is used, there is a gauge meter error. It will be.

Therefore, by estimating the gauge meter error from the set load and the actual load of the i + 1 stand predicted by the equation (6), the i stand stand-out side, that is, the i + 1 stand stand-in side and the i + 1 stand stand-out side, which are the factors of plate thickness error, are estimated. Of the gauge meter plate thicknesses h _ig and h _{i + 1g} , and using these corrected gauge meter plate thicknesses h _ig and h _{i + 1g} , the error of the coefficient C _KQ , which is a non-plate thickness error factor, is corrected again and Estimate with high accuracy and correct.

Further, _{i +} is calculated by using the corrected plate thickness h _{i + 1g} which is the factor of the plate thickness error and the coefficient C _KQ which is the factor of the non-plate thickness error.
The correction load of the two stands is predicted, and the roll gap correction amount of the rolling roll of the i + 2 stand which is highly accurately predicted from the predicted load value and the correction gauge meter formula is set.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In this example, an example of hot finish rolling consisting of three stands as shown in FIG. 1 will be described.

FIG. 1 shows the contents described below.
This figure shows a step of performing a normal gap setup (normal setup) of the F1 stand, the F2 stand and the F3 stand before passing the rolled material S, and a gap adjustment of the F2 stand and the F3 stand after the F1 stand of the rolled material S is engaged ( It shows the steps of performing (passing setup adjustment), the steps of passing the F2 stand after the rolled material S is engaged, and the steps of passing the F3 stand after the rolled material S is engaged with the F3 stand.

That is, in the present embodiment, from the actual load and plate thickness immediately after the F1 stand is bitten and the setup value, F
Calculate the coefficient C _KQ1 for one stand. From now on F
2 Adjust the load of the stand and set up. Furthermore, the gauge meter error is estimated from the actual load of the rolled material and plate thickness at the F2 stand and the setup value, and
Correct the stand and F2 stand exit side actual plate thickness (gauge meter plate thickness). Further, the coefficient C _KQ2 in the F2 stand is again estimated with high accuracy using these correction values, and the coefficient is corrected.

Then, the predicted load value of the F3 stand is corrected using the plate thickness correction value which is the factor of the plate thickness error and the coefficient C _KQ2 which is the factor of the non-plate thickness error and the setup value of the F3 stand, and this correction is further performed. The setup gap error of the F3 stand is corrected by the predicted load value and the gauge meter formula.

In this embodiment, first, before passing the rolled material S,
The setting calculation is performed according to the temperature and plate thickness of the rolled material S, and the normal gap setup (normal setup) of the F1 stand, the F2 stand and the F3 stand is performed.

The details after the rolled material S is bitten into the F1 stand will be described in detail.
The following processes are sequentially executed at the timing before the stand is bitten. Calculate C _KQ1 . From equation (5),

[0045]

(Equation 7)

The number 1 means the F1 stand.
Next, the load prediction correction value; P2 is calculated for the F2 stand. Set the F1 stand exit side record as the F2 entry side record and F1
Assuming that the target on the stand exit side is the target on the F2 stand entrance side, from equation (6),

[0047]

(Equation 8)

The number 2 means the F2 stand. F2 setup gap correction amount; _{ΔSo 2DSU} is calculated, and the gap is moved before the engagement of F2.

[0049]

[Equation 9]

Α ₂ is an adjustment coefficient. F1 stand and F2
Assuming that the actual plate thickness on the stand exit side is [h1] and [h2], the actual load of the F2 stand is

[0051]

[Equation 10] Becomes Here, the gauge meter plate thickness error is δ _g, and as one of the methods

[0052]

[Equation 11] Then, δ _g is estimated by the following equation from the ratio of P2 and P2 ^* .

[0053]

(Equation 12) Substituting this into equation (11), actual plate thickness; [h1], [h
2] and estimate the CKQ value at F2

[0054]

(Equation 13) Calculate the load prediction correction value of F3 from equation (6)

[0055]

[Equation 14] After calculating, F3 setup gap correction amount; ΔS
o Calculate _3DSU and move the gap before F3 bite.

[0056]

(Equation 15)

The F1 stand and the F3 stand are set in accordance with the reduction correction amounts of the F2 stand and the F3 stand, respectively.
Correct the roll speed of the two stands. The present invention is not limited to the above-described embodiments and can be implemented with various modifications. First, when the number of stands is large, each gauge meter error is estimated from the actual load of the upstream side stands and / or C _KQ is calculated, and the average value or extrapolated value is used to determine the downstream stand. There is also a way to fix the gap in.

If there is no strip width meter on the stand-in side, the strip width actual value cannot be used for the setup calculation, so that an error occurs in the value used in the calculation. in this case,
It is also possible to consider the plate width included in C _KQ in equation (4). There is no problem with the control effect because the plate width has an error that is common to all stands.

Furthermore, although a new cost burden is incurred, a gauge is installed on the exit side of F1 and gauge gauge thickness: h _1g
It is also effective to apply the measured plate thickness; h ₁ instead of. However, the following formulas are used in place of the formulas (7), (8), (12) and (13).

[0060]

[Equation 16]

[0061]

As described above, according to the method for correcting the setup at the time of strip passing in the continuous rolling of the present invention, when the rolled material made of the metal material is continuously rolled through the rolling stands provided in the plurality of stands, respectively. After setting up the roll gap of the rolling rolls of the plurality of stands before passing the strip, calculate the setup error of the stand downstream from that stand based on the rolling record of the specific stand when passing the strip, and Is a method for correcting the roll gap before the rolled material reaches, and a non-plate thickness error factor is estimated from the load and plate thickness record of an arbitrary i stand, and the load correction of the i + 1 stand is performed based on this estimation result. I set it up, estimated the gauge meter error from the actual load and plate thickness of the i + 1 stand, and based on this estimation result The gauge thickness on the inlet side and the outlet side of the i + 1 stand, which is the cause of the thickness error, is corrected, the non-thickness error factor is estimated again using the corrected value, and the corrected thickness error is then corrected. Factor and the non-plate thickness error factor are used to predict the load of the i + 2 stand, and based on this predicted load and the modified gauge meter formula, i +
It is characterized in that the roll gap value of two stands is corrected.

Therefore, it is possible to easily and highly accurately compensate for the setup error of the downstream stand, and the rolled product is excellent in strip thickness precision from the tip excluding the influence of the error that is unavoidable only by the setup before strip running. As a result, it is possible to reduce the cut-off portion generated at the end of the rolled material and improve the yield in continuous rolling.

Therefore, according to the present invention, the setup error of the downstream stand can be easily and accurately compensated, and the setup correction method at the time of strip passing in continuous rolling which is excellent in practicability can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the method of the present invention.

[Explanation of symbols]

 F1 ... 1st stand, F2 ... 2nd stand, F3 ... 3rd stand, S ... Rolled material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B21B 37/18 BBM 8315-4E B21B 37/02 D BBM

Claims (1)

[Claims] 1. When continuously rolling a rolled material made of a metal material through a rolling stand provided in each of a plurality of stands, after setting up a roll gap of rolling rolls of the plurality of stands before passing, A method for correcting a roll gap before the rolled material reaches the next stand by calculating a setup error of a stand located downstream of the stand from the rolling record of a specific stand during stripping. The non-thickness error factor is estimated from the actual load and the actual plate thickness, the load of the i + 1 stand is corrected based on the estimation result, and the setup is performed. The gauge meter error is estimated from the actual load and plate thickness of the i + 1 stand. Based on the estimation result, correct the gauge meter plate thickness on the inlet side and the outlet side of the i + 1 stand, which is the cause of the plate thickness error, and correct this. The non-plate thickness error factor is re-estimated and corrected using the value, and the i + 2 stand load is predicted using the corrected plate thickness error factor and the non-plate thickness error factor, and the predicted load and correction are performed. A method for correcting the setup during strip passing in continuous rolling, characterized in that the roll gap value of the i + 2 stand is corrected based on the gauge meter formula.