JP2014161875A - Method for identifying mill elongation expression in rolling machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely identify a mill elongation expression used for position control under pressure in a rolling mill.SOLUTION: An identification method is a method for identifying a mill elongation expression used for a thickness control with respect to a rolled material 5 during rolling by a rolling mill 4 including work rolls 2 and 2. An amount of mill elongation of the rolling machine 4 is measured by bringing the work rolls 2 and 2 into a kiss contact and then applying a rolling load thereto. A relation expression of the amount of mill elongation with respect to the rolling load is identified for each region of three rolling loads divided on the basis of a state of the kiss contact of the work rolls 2 and a back-up roll 3.

Description

  The present invention relates to a mill elongation type identification method used for control of a rolling position of a rolling mill.

When rolling a rolled material using a rolling mill, it is necessary to accurately control the thickness of the rolled material. The plate thickness is one of the evaluation criteria for the final product in the rolling mill, and various control technologies (plate thickness control technologies) have been developed to make the plate thickness appropriate.
In these sheet thickness control technologies, the roll gap of the rolling roll is predicted using a gauge meter formula, and the rolling roll of the rolling mill is set up to satisfy the predicted roll gap, and rolling during rolling is performed. The load on the roll is changed to control the thickness of the rolled material.

In controlling the plate thickness using the gauge meter type, it is necessary to obtain a mill constant in advance in order to calculate the mill elongation due to the rolling load. The following literature discloses a technique related to such plate thickness control.
Japanese Patent Laid-Open No. 6-254613 (Patent Document 1) discloses a rolling that enables highly precise reduction position control by using a gauge meter capable of predicting an accurate deformation amount of a rolling mill for a rolled material having an arbitrary size. Disclosed is a thickness control method for a machine. The sheet thickness control method disclosed in Patent Document 1 calculates a roll deformation amount with respect to a rolling load based on a roll dimension, a roll crown, a sheet width, and a sheet thickness, and tightens while rotating the roll in a kiss roll state. By subtracting the roll deformation amount calculated based on the non-contact length of the work rolls in the kiss roll state, the roll dimensions, and the roll crown from the measured total mill elongation amount, the deformation amount other than the roll with respect to the rolling load is calculated, The reduction position control is performed using a gauge meter formula composed of the calculated roll deformation amount and the deformation amount other than the roll.

  Japanese Patent Application Laid-Open No. 61-269923 (Patent Document 2) discloses that, when controlling the thickness of a rolling mill using a gauge meter type, the error resulting from the change in roll profile is reduced using a correction coefficient determined from the roll profile. Disclosed is a sheet thickness control method in a rolling mill that can improve the thickness accuracy of the delivery side sheet. In the sheet thickness control method disclosed in Patent Document 2, when a rolling mill is set at the rolling position and rolled, a roll profile that changes during rolling is measured with a roll profile detector, or a roll friction type or the like is used. Prediction is performed using a roll profile prediction formula, and a parameter representing the influence of the roll profile with time is taken into the term of the roll deformation formula, and the reduction position is calculated and adjusted based on a gauge meter formula taking into account the effect of the roll profile.

  Japanese Patent Application Laid-Open No. 6-226322 (Patent Document 3) discloses a stable supply of products that can further improve plate thickness control accuracy in plate rolling performed using a gage meter type and can sufficiently meet severe accuracy requirements. Disclosed is a method for controlling the thickness of a sheet in rolling. The sheet thickness control method disclosed in Patent Document 3 separates and captures the deformation amount of a rolling mill into a roll system deformation amount and a housing system deformation amount, and calculates the housing system deformation amount at the time of roll tightening. In the basic formula calculated based on the tightening mill rigidity value, a formula that incorporates parameters representing the effect of roll opening is set, and the housing system deformation amount, roll system deformation amount, roll The reduction position is calculated and adjusted based on a gauge meter equation related to the opening degree and the roll opening degree correction term.

  Japanese Patent Application Laid-Open No. 58-28004 (Patent Document 4) describes a hot rolling mill, particularly a hot rolling machine that determines the mill rigidity of a hot rolling mill such as a thick plate rolling mill that does not apply tension to the material to be rolled during rolling. Disclosed is a method for determining the mill rigidity of a rolling mill. The method of determining the mill rigidity disclosed in Patent Document 4 is based on the mill rigidity obtained from the relationship between the rolling position and the rolling force when a normal temperature steel sheet is placed on a roll of a rolling mill and the rolling is applied. The mill rigidity of the hot rolling mill at the time of actual rolling is determined based on the rolling force in rolling and the measured thickness value and the calculated thickness value obtained by calculation.

JP-A-6-254613 JP-A 61-269923 JP-A-6-226322 JP 58-28004 A

  In the above-mentioned patent document, in determining the mill constant (in other words, the relationship between the rolling load and the mill elongation), the rolling is performed in a kiss roll state before rolling, and the relationship line between the rolling position and the reaction force of the rolling force. Obtaining the figure, separating the roll position (mill elongation = total elongation) into roll deformation and housing deformation (Patent Documents 1 to 3), and biting the steel sheet at room temperature into the roll before rolling Further, there is a method in which reduction is applied, a relationship diagram between the reduction position and the reaction force of the rolling force at this time is obtained, and the mill rigidity is obtained by using the slope of the straight line portion of this diagram as a function of the plate width. In any of these methods, in determining the mill constant, the relationship between the rolling position and the rolling reaction force is actually measured at a certain number of measurement points in order to ensure sufficient accuracy. It is necessary to approximate the measurement point by some function (for example, an Nth order function (N = natural number) by the method of least squares). From such a point of view, the applicant actually measured a certain number of measurement points, created a relationship diagram between the rolling position and the rolling reaction force, and approximated it by a quadratic function by the method of least squares.

  However, it has been found that a large error occurs in the mill elongation periodically with respect to the rolling reaction force. This is shown as the conventional error in FIG. In this case, even if the relationship between the rolling position and the rolling reaction force is measured accurately with respect to a large number of points, a highly accurate relationship diagram (mill elongation formula) cannot be obtained. As a result, the accuracy of plate thickness control based on the gauge meter type is reduced. Such a tendency is the same for a higher-order function (for example, an eighth order) than a quadratic function.

  Then, in view of such a problem, an object of the present invention is to provide a method for accurately identifying a mill elongation type used for rolling position control of a rolling mill.

In order to achieve the above-described object, the present invention takes the following technical means.
The mill elongation type identification method according to the present invention identifies a mill elongation type used for the rolling position control of a rolling mill equipped with a work roll and a backup roll. In this identification method, based on the measurement step of measuring the mill elongation of the rolling mill by applying a rolling load after bringing the work roll into kiss contact, and the state of kiss contact between the work roll and the backup roll. And an identifying step for identifying a relational expression of mill elongation with respect to rolling load.

Preferably, the identification step sets two or more rolling load regions based on the kiss contact state of the work roll and the backup roll, and the mill elongation amount relative to the rolling load is set for each of the two or more set rolling load regions. It can comprise so that the calculation step which calculates a relational expression may be included.
More preferably, the calculating step may include a step of identifying the relational expression so that the relational expression of the mill elongation amount is continuous at the boundary of the rolling load region.

  More preferably, the mill elongation amount can include a deformation amount of the work roll and the backup roll, and a deformation amount of a portion that supports the work roll and the backup roll.

  According to the identification method of the present invention, it is possible to identify the mill elongation type used for the rolling position control of the rolling mill with high accuracy, and to control the plate thickness with high accuracy.

It is the schematic which shows the structure of the rolling apparatus with which the mill elongation type identification method which concerns on the 1st Embodiment of this invention is applied. It is a figure which shows the relationship between a rolling load and total elongation (mill elongation). It is a figure for demonstrating the contact state between rolls. It is a figure which shows the contact surface pressure between the rolls at the time of a low load. It is a figure which shows the contact surface pressure between the rolls at the time of a high load. FIG. 3 is a second-order approximation of the rolling load divided into three regions in FIG. 2. It is a figure which shows the approximation error of the total elongation with respect to a rolling load. It is a figure which shows the mill elongation type identification method which concerns on the 2nd Embodiment of this invention.

Hereinafter, the mill elongation type identification method according to the embodiment of the present invention will be described. In the following, unless otherwise specified, the mill elongation amount and the total elongation amount are synonymous (the mill elongation type and the total elongation type are also synonymous), and the deformation amount other than the roll deformation amount and the roll deformation amount (for example, the housing) Deformation amount).
<First Embodiment>
With reference to FIG. 1, a rolling apparatus 1 to which a mill elongation type identification method according to a first embodiment is applicable will be described.

[Device configuration]
As shown in FIG. 1, the rolling device 1 is for rolling a thick steel plate or a thin steel plate, and includes a rolling mill 4 and a control unit 9 that controls the rolling mill 4.
The rolling mill 4 includes a work roll 2 through a pair of upper and lower work rolls 2 and 2, a pair of backup rolls 3 and 3 that support the work rolls 2 and 2, and an upper backup roll 3. There are gap changing means for making the roll gap variable, and load measuring means for measuring and outputting the rolling load. The abbreviation “WR” represents a work roll, and the abbreviation “BUR” represents a backup roll.

The gap changing means is constituted by a hydraulic cylinder 6, and the load measuring means is constituted by a load cell 10 or the like.
The gap changing means can independently drive the chock portions 11 that support both ends of the work roll 2. One end side of the work roll 2 is connected to a drive motor that drives the work roll 2 and is a drive side. The other end side of the work roll 2 is not connected to a drive motor, and is a work side in which a space for an operator to work is secured.

  A rolling material 5 serving as a base plate is introduced into the rolling mill 4 and subjected to rolling, and then sent to a lower process. An entry side thickness gauge 7 for measuring the entry side thickness H of the rolled material 5 is installed on the entry side of the rolling mill 4, and an exit side thickness h of the rolling material 5 is measured on the exit side of the rolling mill 4. A side plate thickness gauge 8 (not shown) is installed. As the entrance side thickness gauge 7 and the exit side thickness gauge 8, a γ-ray thickness gauge or the like can be employed.

In addition, when there is no space for providing the entrance side thickness gauge 7, the exit side thickness of the rolling mill in the upper process can be adopted as the entry side thickness.
Furthermore, the rolling device 1 is provided with a control unit 9 that controls the rolling load P and the roll gap amount s of the rolling mill 4.
The control unit 9 has a thickness control function for controlling the rolling mill 4 so that the outlet side thickness h of the rolled material 5 falls within a predetermined range or is constant. As a control method performed by the control unit 9, a known plate thickness control method is employed. For example, feed forward AGC, BISRA AGC, monitor AGC, mass flow AGC, tension AGC, etc. are applicable. Information such as the entry side plate thickness H, rolling load P, and rolling material tension of the rolling mill 4 is input to the control unit 9, and the roll gap amount s and roll speed of the rolling mill 4 are based on the input information. Is calculated and output.

The control unit 9 described above is realized by a process computer or PLC.
Hereinafter, a mill elongation type identification method in the rolling mill 4 performed by the control unit 9 of the present embodiment will be described with reference to FIGS.
[Measurement step]
First, without introducing the rolling material 5 into the rolling device 1, the rolling load P is applied after the work rolls 2 and 2 are brought into kiss contact. Thereby, the mill elongation amount (total elongation amount) of the rolling mill 4 measured by tightening in the kiss roll state is measured. The amount of mill elongation at this time includes the deformation amount of the work rolls 2 and 2 and the backup rolls 3 and 3 and the deformation amount of the portion (housing) that supports the work roll 2 and the backup roll 3. Become.

In the mill elongation formula identification method according to the present embodiment, a relational expression that can accurately calculate the mill elongation amount with respect to the rolling load P can be identified. In this respect, the mill elongation amount differs from Patent Document 1 in which analysis is performed by dividing the amount of deformation of the housing other than the roll (housing deformation amount) and roll deformation amount.
FIG. 2 shows the relationship between the rolling load P and the mill elongation (total elongation, reduction position) measured in such a measurement step.

  As shown in FIG. 2, it can be seen that the mill elongation increases monotonously as the rolling load P increases. In addition, as shown in FIG. 2, in order to identify the relational expression (relational expression between the rolling position and the rolling load P (rolling reaction force)) with sufficient accuracy, a certain number of measurement points were actually measured. ing. When a relationship diagram between the rolling position and the rolling reaction force is created and approximated by a quadratic function based on the least square method, as described above, as shown as a conventional error in FIG. It was found that a large error occurred in the mill elongation.

Therefore, in the mill elongation type identification method according to the present embodiment, the mill for the rolling load P is determined based on the kiss contact state of the work rolls 2 and 2 and the backup rolls 3 and 3 in the identification step shown below. The relational expression of elongation is identified.
[Identification step]
An initial profile is given to the work rolls 2 and 2 and the backup rolls 3 and 3, and the apparent mill constant (in other words, the relationship between the rolling load and the mill elongation) is changed by changing the contact state between these rolls. ) Varies depending on the region of the rolling load P.

This will be described with reference to FIG.
FIG. 3A shows a state where the work roll 2 and the work roll 2 are partially in contact, and the work roll 2 and the backup roll 3 are partially in contact. In this state, since the displacement of the mill elongation with respect to the rolling load P appears greatly, the apparent mill constant becomes small.

FIG. 3B shows a state in which the work roll 2 and the work roll 2 are in partial contact, and the work roll 2 and the backup roll 3 are in full contact. The work roll 2 and the backup roll 3 come into full contact before the work roll 2 and the work roll 2 come into full contact.
FIG. 3C shows a state where the work roll 2 and the work roll 2 are in full contact, and the work roll 2 and the backup roll 3 are in full contact. In this state, since the displacement of the mill elongation with respect to the rolling load P appears small, the apparent mill constant becomes large.

  As described above, since the displacement of the mill elongation with respect to the change in rolling load changes depending on the contact state between the work roll 2 and the work roll 2 and the contact state between the work roll 2 and the backup roll 3, (A) Work roll The rolling load at which the work roll 2 and the work roll 2 are in full contact with each other and (B) the rolling load at which the work roll 2 and the backup roll 3 are in full contact with each other are calculated and distinguished according to the contact state of the rolls. An approximate expression of mill elongation was obtained by dividing into two rolling load regions.

FIG. 4A shows the contact surface pressure between the work roll 2 and the work roll 2 when 1420 [tonf] is applied as the rolling load P, and FIG. 4B shows the contact surface pressure between the work roll 2 and the backup roll 3. ) Respectively.
Furthermore, FIG. 5A shows the contact surface pressure between the work roll 2 and the work roll 2 when 2620 [tonf] is applied as the rolling load P, and FIG. 5 shows the contact surface pressure between the work roll 2 and the backup roll 3. Each is shown in (b).

As shown in FIG. 4A, in 1420 [tonf], it can be seen that there is a non-contact region between the work roll 2 and the work roll 2, which is a partial contact state. As shown in FIG. 4B, it can be seen that in 1420 [tonf], there is no non-contact area between the work roll 2 and the backup roll 3, and the entire surface is in a contact state.
As shown in FIG. 5A, it can be seen that in this 2620 [tonf], there is no non-contact area between the work roll 2 and the work roll 2, and the entire surface is in a contact state. As shown in FIG. 5B, it can be seen that there is no non-contact area between the work roll 2 and the backup roll 3 in 2620 [tonf], and the entire surface is in a contact state.

  From these facts, as shown in FIG. 6, as the region (I), the work roll 2 and the work roll 2 are in partial contact, and the work roll 2 and the backup roll 3 are in partial contact. In the region of 1420 [tonf], as the region (II), the work roll 2 and the work roll 2 are in partial contact, and the work roll 2 and the backup roll 3 are in full contact with each other, and the rolling loads 1420 to 2620 [tonf] As the region and the region (III), the work roll 2 and the work roll 2 are in full contact with each other, and the work roll 2 and the backup roll 3 are in full contact with each other. It was set.

  In these three regions, relational expressions (three formulas) that approximated the mill elongation with respect to the rolling load in a second order were calculated. Note that the order of the approximate expression is not limited to the second order. FIG. 7 shows a conventional error for comparison and an error due to the method of identifying the mill elongation according to the present embodiment. As shown in FIG. 7, the conventional error was an average of −0.1 [μm] with a deviation of 59.3 [μm], whereas the error of the present invention was an average of −0. It can be seen that the improvement is 9 [μm].

As described above, according to the method for identifying the mill elongation formula according to the first embodiment, an approximate expression for the mill elongation amount was obtained by dividing the three rolling load regions distinguished according to the contact state of the roll. Therefore, the mill elongation type used for the rolling position control of the rolling mill can be identified with high accuracy, and the plate thickness can be controlled with high accuracy.
The number of rolling load areas to be divided is not limited to three. Further, the rolling load at the boundary is not limited to the above-described 1420 [tonf] and 2620 [tonf]. The number of regions and / or the rolling load at the boundary is appropriately set in consideration of the contact state between the work roll 2 and the work roll 2 and the contact state between the work roll 2 and the backup roll 3.

<Second Embodiment>
Hereinafter, the mill elongation type identification method according to the second embodiment of the present invention will be described. In addition, since the rolling apparatus 1 to which this identification method is applied suitably is as FIG. 1, detailed description here is not repeated. Moreover, since it is the same as 1st Embodiment mentioned above about the point divided into three rolling load area | regions distinguished according to all the measurement steps and the contact state of the roll in an identification step, it is detailed here. The explanation will not be repeated.

In the identification method of the mill elongation formula according to the present embodiment, when the quadratic approximation is performed after dividing into the three rolling load regions in the identification step, the mill elongation formula is continuous at the boundary of the rolling load region. It is characterized by identifying the mill elongation formula.
In other words, the mill stretch equation is the continuous in rolling load boundary _{P 2} of 8, region rolling load boundary _{P 1} and regions of (I) and region (II) (II) a region (III) and Thus, the mill elongation formula approximated by the second order is identified. For this purpose, the mill elongation formula is identified using the following formulas (1) to (3). Thereby, it is possible to identify a mill elongation formula that is quadratic approximated so that the mill elongation formula is continuous at the rolling load boundary.

As described above, according to the mill elongation type identification method according to the second embodiment, the mill is divided into three rolling load regions that are distinguished according to the contact state of the roll, and continuous at the boundary. An approximate expression of elongation can be obtained.
In addition, it is preferable to identify a mill elongation formula from the area | region where the rolling load P including an actual rolling area | region is large.

<Modification>
Hereinafter, modifications of the embodiment of the present invention will be described. This modification is different in the identification target expression. In the first embodiment and the second embodiment described above, the identification target is a mill elongation type (total elongation type), but in this modification, the identification target is the amount of deformation of the housing with respect to the rolling load P. This is an approximate expression (deformation amount other than the roll deformation amount) or an approximate expression of the roll deformation amount with respect to the rolling load P. The identification target can be both an approximate expression for the housing deformation amount (deformation amount other than the roll deformation amount) and an approximate expression for the roll deformation amount. In many cases, it is a preferable approximation result.

In this way, the roll deformation is not applied to the mill elongation type, but applied to an approximate expression (roll elongation type) of the roll deformation amount constituting the mill elongation amount and / or a deformation amount other than the roll deformation amount (housing elongation type). The amount and / or the amount of housing deformation can be calculated with high accuracy, and as a result, the plate thickness can be controlled with high accuracy in the rolling position control of the rolling mill.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. In particular, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of the constituents are within the range normally practiced by those skilled in the art. It does not deviate and employs a value that can be easily assumed by those skilled in the art.

DESCRIPTION OF SYMBOLS 1 Rolling apparatus 2 Work roll 3 Backup roll 4 Rolling mill 5 Rolled material 6 Hydraulic cylinder 7 Entry side thickness gauge 8 Delivery side thickness gauge 9 Control part 10 Load cell 11 Chock part

Claims (4)

In the mill elongation type identification method used for the rolling position control of a rolling mill equipped with a work roll and a backup roll,
Measuring step of measuring the mill elongation of the rolling mill by applying a rolling load after kissing the work roll;
An identification step for identifying a relational expression of the mill elongation with respect to the rolling load based on the kiss contact state of the work roll and the backup roll;
A method for identifying a mill elongation type, comprising:   In the identification step, two or more rolling load regions are set based on the kiss contact state of the work roll and the backup roll, and a relational expression of the mill elongation amount with respect to the rolling load is set for each of the two or more set rolling load regions. The method according to claim 1, further comprising a calculating step of calculating.   The said calculating step includes the step of identifying the said relational expression so that the relational expression of mill elongation amount may become continuous in the boundary of the said rolling load area | region, The mill elongation type | formula of Claim 2 characterized by the above-mentioned. Identification method.   The said mill elongation amount contains the deformation amount of the said work roll and the said backup roll, and the deformation amount of the site | part which supports the said work roll and the backup roll, The any one of Claims 1-3 characterized by the above-mentioned. 2. The method for identifying the mill elongation formula described in 1.