JP2004066263A - Method for rolling structual steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for rolling bar steel, by which highly precise dimensional control is attained without any dimensional variation over the entire length of a product. <P>SOLUTION: When expressing the velocity in the top part of a material 13 to be rolled between a finishing mill 4 and the final finishing mill 5 until the nose of the material 13 to be rolled enters the final finishing mill 5 by V0 and the velocity of the middle part of the material 13 to be rolled until the rear end of the material 13 to be rolled is passed through the finishing mill 4 by V1, the value of a linear velocity ratio : R=ä(V1-V0)/V0}×100 at which the dimensions over the entire length of the product after the final finish rolling is made uniform is beforehand determined. The velocity of the top part is measured in actual operation and, when expressing the measured value by V0', the target velocity V1' of the middle part is determined by V1'=V0'+V0'×R/100 by using the value of the predetermined linear velocity ratio R. By controlling the revolving speed of the driving motor of the final finishing mill 5 before the nose of the material 13 to be rolled enters the final finishing mill 5, the velocity of the middle part of the material 13 to be rolled is controlled so as to be the target velocity V1' of the middle part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for rolling a steel bar. The “strip steel” in the present invention refers to a wire rod or a steel bar.
[0002]
[Prior art]
The dimensional accuracy of the rolled product in the continuous bar rolling mill is affected by the tension acting on the material to be rolled. If the tension is increased, the difference in eccentricity increases (the roundness deteriorates). On the other hand, when the tension is lost, the material to be rolled pulsates between the roll stands, and a cobble (misroll: clogging of the rolled material during passage) occurs.
Therefore, in order to improve the dimensional accuracy of the product and reduce the dimensional fluctuation without generating cobbles, it is necessary to control the tension (tension) acting on the material to be rolled to a minimum and a constant value.
[0003]
2. Description of the Related Art Conventionally, as a tension control technique in a continuous steel bar rolling line, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 4-89124 is known.
This conventional technique is provided at a subsequent stage of a first wire rod rolling mill having a constant rolling speed, and a speed of a second wire rolling mill for further performing high-precision finishing rolling subsequent to the rolling of the first wire rolling mill. A pulsation detection device that detects pulsation of the wire rod that has passed through the first wire rolling mill, and a pulsation of the wire rod detected by the pulsation detection device, wherein the pulsation is eliminated so that the pulsation is eliminated. And a rotation speed control means for controlling the rotation speed of the second wire rod rolling mill.
[0004]
According to this conventional technique, the pulsation of the wire passing through the first wire rolling mill is detected by the pulsation detection device, and the second wire rod is eliminated by the rotation speed control means based on the pulsation. Since the rotation speed of the rolling mill is controlled, the tension of the wire is properly maintained without pulling or loosening of the wire before the second wire rolling mill, and the dimensional accuracy of the wire is reduced or the wire is broken. And a highly accurate wire rod was obtained efficiently.
[0005]
[Problems to be solved by the invention]
However, the conventional tension control described in Japanese Patent Application Laid-Open No. 4-89124 has problems such as calculation delay and calculation error because pulsation detection, that is, tension detection of the wire is performed by image processing. .
Further, since the above-described conventional apparatus detects pulsation of the wire rod, the control is performed in a state where the wire rod is being rolled by the first and second wire rod rolling mills. , It is difficult to control the wire rod from the moment it is bitten into the second wire rod rolling mill, an uncontrolled portion remains at the wire rod tip, and the wire rod tail end cannot be controlled. In addition, it was difficult to control the dimensional fluctuation over the entire length of the product.
[0006]
Further, the conventional device has a problem that the product dimensions cannot be adjusted to the target value because the tension is only controlled.
In view of the above, an object of the present invention is to improve the problems described in the related art, that is, to guarantee product dimensions over the entire length without performing complicated arithmetic processing.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention takes the following measures. That is, the feature of the present invention is a method of rolling a strip steel in which a material to be rolled is rolled on a rolling line including a finish rolling mill and a final finishing mill on the downstream side, wherein the tip of the material to be rolled is The speed of the top portion of the material to be rolled between the finishing mill and the final finishing mill before leaving the finishing mill and entering the final finishing mill is V0, and the rear end of the material to be rolled is finished. When the speed of the middle part of the material to be rolled before leaving the rolling mill is V1, the linear speed ratio R = ｛(V1-V0) / V0 at which the dimensions are uniform over the entire length of the product after leaving the final finishing rolling mill. A value of 値 × 100 is determined in advance, and the top portion speed is measured in actual operation. When the measured value is V0 ′, the target middle speed is calculated using the value of the linear speed ratio R determined in advance. V1 ′ = V0 ′ + V0 ′ × R / 00, and before the leading end of the material to be rolled enters the final finishing mill, controlling the rotation speed of the drive motor of the final finishing mill to set the middle speed of the material to be rolled to the target middle portion speed. V1 '.
[0008]
According to the present invention having the above-described configuration, before the leading end of the material to be rolled enters the final finishing mill, the drive motor rotation speed of the final finishing mill is controlled, so that the dimensional variation is constant over the entire product length. You.
Another feature of the present invention is that in a method of rolling a strip steel in which a material to be rolled is rolled on a rolling line including a finish rolling mill and a final finishing mill on the downstream side, the tip of the material to be rolled is Before leaving the finishing mill and entering the final finishing mill, the top speed of the material to be rolled between the finishing mill and the final finishing mill is V0, and the rear end of the material to be rolled is When the speed of the middle part of the material to be rolled before passing through the finishing mill is V1, the linear speed ratio R = ｛(V1-V0) at which the dimensions are uniform over the entire length of the product after leaving the final finishing mill. / V0｝ × 100 is determined in advance, the top portion speed is measured in actual operation, and when the measured value is set to V0 ′, the value of the linear speed ratio R determined in advance is used. The target middle part speed V1 'is calculated as follows: V1' = V0 '+ V0' × / 100, and while the final finishing mill is rolling the material to be rolled, the speed of the drive motor of the final finishing rolling mill is controlled to set the middle speed of the material to be rolled to the target middle speed V1. The point is to control so that
[0009]
According to the present invention having the above-described configuration, control is performed after the material to be rolled is bitten into the final finishing rolling mill. However, since the arithmetic processing of the present invention is extremely simple, processing is performed without time delay. As a result, since control can be performed from the moment of being bitten, there is no uncontrolled portion at the tip as in the prior art, and uniform control can be performed over the entire length of the product.
The relationship between the roll peripheral speed Vr of the final finishing mill at the linear speed ratio R and the speed V1 of the material to be rolled is determined in advance, and based on this relationship, the target middle portion speed V1 ′ is set. Preferably, the number of rotations of the drive motor of the final finishing mill is controlled.
[0010]
According to the present invention having the above-described configuration, the relationship obtained in advance can be stored and processed as a table or the like, so that the processing speed is increased.
The relationship between the roll gap variation ΔS of the final finishing mill and the product dimension variation Δd and the relationship between the roll gap variation ΔS and the roll peripheral speed variation ΔVr at the linear speed ratio R are determined in advance, and these relationships are used as a basis. In addition, the roll gap of the final finish rolling mill is controlled so that the product dimension becomes an appropriate dimension, and the drive motor rotation speed of the final finishing mill is controlled so that the target middle section speed V1 ′ is achieved. Is preferred.
[0011]
By performing such processing, the product dimensions can be set to the target values.
The relationship between the exit side dimensional variation Δdm of the finishing mill and the product dimensional variation Δd, and the relationship between the dimensional variation Δdm at the linear speed ratio R and the roll peripheral speed variation ΔVr of the final finishing mill are previously determined. Based on these relations, based on these relationships, the exit dimension dm of the finishing mill is controlled so that the product dimensions are appropriate, and the final finish rolling is performed so that the target middle part speed V1 'is achieved. It is also possible to control the rotation speed of the drive motor of the machine.
[0012]
The linear velocity ratio R is preferably set to 0.1 to 5%.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a layout of wire rod rolling.
In this rolling line, a billet heated in a heating furnace 1 is rolled by a rough rolling mill 2 and an intermediate rolling mill 3, then rolled by a finishing rolling mill 4 and a final finishing rolling mill 5, and wound up by a laying head 6. is there. Usually, a water cooling device 7 is provided between the finishing mill 4 and the final finishing mill 5.
[0014]
A block mill is adopted as the finish rolling mill 4 and the final finishing rolling mill 5, for example, in the case of a wire rod having a diameter of 5.5 mm, the linear velocity at the exit side of the finishing rolling mill 4 is 80 m / s, and the final finishing rolling mill is used. The speed at 5 is a high speed such as 120 m / s.
The "block mill" here is a common drive device usually composed of a variable speed electric motor, and means a rolling mill in which a plurality of stands are driven, and naturally includes a sizing mill.
In the rolling deformation in the wire rod rolling, when front and rear tensions are applied, the width of the free surface after rolling is reduced. For this reason, in the intermediate rolling mill 3, a loop is formed between the stands so that the tension between the stands is zero and constant, and the roll rotation speed of each stand is adjusted so that the loop amount is constant. Control is performed.
[0015]
However, the speed between the finishing mill 4 and the final finishing mill 5 is high speed and small in diameter, and there is a danger of cobbles due to the formation of a loop, so that loop control becomes impossible.
The present invention relates to the tension control between such a finishing mill 4 and the final finishing mill 5.
FIG. 2 shows a change in the width dimension of the entire product length when there is tension between the finishing mill 4 and the final finishing mill 5.
[0016]
FIG. 3 shows a change in the width dimension of the entire product length when the tension between the finishing mill 4 and the final finishing mill 5 is reduced.
In FIG. 2, the reason why the width dimension of the product middle part is smaller than that of the bottom part is that tension acts between the rolling mills 4 and 5.
When the tension is reduced and the tension becomes almost zero, the dimension becomes uniform over the entire length of the product as shown in FIG. 3, but is out of the target value.
When the value is out of the target value, the roll gap S of the first stand of the final finishing mill 5 is generally lowered to adjust the size. Such deviation from the target value is caused by the type of steel to be rolled, the rolling temperature, the rolling speed, the wear of the die, and the like, and the adjustment of the roll gap S is always necessary.
[0017]
From the above, it can be seen that in order to make the product the target size over the entire length, it is necessary to adjust the fluctuation of the entire length by adjusting the tension between the rolling mills 4 and 5, and adjust the roll gap S to the target value.
In view of the above, the present invention intends to control the tension adjustment without calculating the tension by calculation or the like.
FIG. 4 is a detailed view of the finishing mill 4 and the final finishing mill 5 in FIG. 1, and the water cooling device 7 is not shown.
[0018]
The finishing mill 4 employs a block mill, in which a plurality of rows of work rolls (a combination of horizontal rolls and vertical rolls) are arranged in series, and a single drive for rotating these work rolls is used. A motor 8 is provided. In addition, a reduction device 9 for setting the reduction amount of each work roll is provided.
The final finishing mill 5 employs a sizing mill, in which a plurality of rows of work rolls (a combination of horizontal rolls and vertical rolls) are arranged in series, and a single drive motor 11 for rotating these work rolls is used. Is provided. In addition, a reduction device 12 for setting the reduction amount of each work roll is provided.
[0019]
A main controller 12 for controlling the drive motors 8 and 10 of the finishing mill 4 and the final finishing mill 5 and the rolling-down devices 9 and 11 is provided.
A moving speed measuring device 14 for measuring the moving speed of the material 13 to be rolled is provided between the finishing mill 4 and the final finishing mill 5. The moving speed measuring device 14 is constituted by a linear velocimeter.
This linear velocity meter is composed of, for example, a laser Doppler linear velocity meter, and is disposed substantially at the center between the two rolling mills 4 and 5, and the moving speed V0 at the top of the material 13 to be rolled (when the tip of the material 13 The speed at which the final finish rolling mill 5 is engaged, the middle portion moving speed V1 (the speed in the state of being rolled by the finish rolling mill 4 and the final finish rolling mill 5), and the bottom portion moving speed V2 (the material to be rolled) 13 is measured after the rear end of the roll 13 has passed through the finishing mill 4).
[0020]
In order to recognize whether the moving speed of the material to be rolled 13 measured by the linear velocity meter 14 is the top moving speed V0, the middle moving speed V1, or the bottom moving speed V2, the finishing rolling mill is used. 4 is provided with a first position detection sensor 15 on the exit side and a second position detection sensor 16 on the entrance side of the final finishing mill 5. These position detection sensors 15 and 16 are constituted by, for example, hot steel detection sensors capable of detecting the hot rolled material 13. When only the first position detection sensor 15 is detecting the material 13 to be rolled, the top position moving speed V0 is recognized, and both the first and second position detection sensors 15 and 16 detect the material 13 to be rolled. The main control device 12 is configured to recognize the middle part moving speed V1 when it is present, and recognize the bottom part moving speed V2 when only the second position detection sensor 16 is detecting.
[0021]
Further, a first dimension measuring device 17 for measuring the dimensions of the material 13 to be rolled and a tension measuring device 18 for measuring the tension of the material 13 to be rolled are provided between the rolling mills 4 and 5. A second dimension measuring device 19 for measuring the dimensions of the material to be rolled (product) 13 is provided on the exit side of the final finishing mill 5.
The first and second dimension measuring devices 17 and 19 have, for example, a light emitter and a light receiver arranged with the material to be rolled 13 interposed therebetween. By rotating around the center, the outer diameter of the material to be rolled 13 at each position of rotation is measured, and the measurement result is sent to the main control device 12 where the size is measured. The deviation (= diameter difference: difference in outer diameter at each measurement position) is determined.
[0022]
The tension measuring device 18 includes, for example, a roller 20 for giving a forcible displacement to the material 13 to be rolled, an elevating device 21 for the roller 20, a displacement sensor for measuring a roller elevating amount of the elevating device 21, It consists of a load cell for measuring the reaction force of the roller when ascending and descending.
The principle of the tension measurement is to apply a forced displacement to the material to be rolled 13 moving between the rolling mills 4 and 5 and calculate the tension from the amount of the forced displacement and the reaction force of the material to be rolled 13. The operation is performed in the main controller 12.
[0023]
The main controller 12 controls the drive motor of the final finishing mill 5 based on the moving speed of the material 13 to be rolled based on the moving speed of the material 13 measured by the moving speed measuring device 14 so that the tension of the material 13 to be rolled becomes an optimum value. 10 is configured to be controlled.
A method of rolling a steel bar in the rolling line having the above configuration will be described below.
First, the solution principle of the present invention will be described.
FIG. 5 shows an example in which the speed of the material 13 to be rolled between the finishing mill 4 and the final finishing mill 5 is measured.
[0024]
From this figure, the speed (top portion speed) V0 until the leading end of the material to be rolled 13 bites into the final finish rolling mill 5, and the speed (middle portion) when both the finish rolling mill 4 and the final finish rolling mill 5 bite. It can be seen that the speed) V1 and the speed (bottom portion speed) V2 after the rear end of the material 13 has passed through the finishing mill 4 are different from each other.
The top portion speed V0, middle portion speed V1, and bottom portion speed V2 are different because tension is acting between the finishing mill 4 and the final finishing mill 5.
Therefore, it can be understood that the tension can be controlled by controlling the above-mentioned speed, and hence the dimensional control of the product can be performed.
[0025]
In this speed control, if the control using the bottom portion speed V2 is performed, the bottom portion speed cannot be known until after the rolling is completed, so that it is not possible to set the conditions before the wire is rolled as in the related art. A problem and a problem that dimensional control during rolling cannot be performed occur.
Therefore, in order to improve this, control is performed using the top portion speed V0 and the middle portion speed V1.
That is, a relational expression between the top portion speed V0 and the middle portion speed V1 is defined as the following expression (1).
[0026]
R = (V1−V0) / V0 × 100 (1)
Then, the relationship between the R value and the width dimension variation of the bottom part of the product (“Bottom” shown in FIG. 2) was examined.
FIG. 6 shows the result. According to FIG. 6, a correlation is recognized between the R value and the width dimension variation amount of the bottom portion.
Therefore, it became clear that the dimensional variation in the bottom part of the product can be controlled by defining the R value.
[0027]
That is, it is possible to determine in advance an optimum R value that does not generate cobbles and guarantees dimensional accuracy over the entire length. Therefore, in actual operation, the middle speed may be controlled so as to obtain the optimum R value.
In the actual operation, a target middle portion speed V1 'is determined by the following equation (2) from the measured rolled material top portion speed V0'.
V1 ′ = V0 ′ + V0 ′ × R / 100 (2)
By controlling the number of revolutions of the final finishing mill 5 so as to achieve this speed, no cobbles are generated and dimensional accuracy can be guaranteed over the entire length.
[0028]
Therefore, in the present invention, it is necessary to determine in advance by experiments or the like the optimum linear velocity ratio R of the product at which the dimensions are uniform over the entire length of the product.
The main control device 12 is provided with a storage means 22 for storing these experimental values R as a relationship as shown in FIG. The main control device 12 is provided with a calculation unit 23 for performing the calculation of the expression (2).
Then, in the actual operation, the linear velocity of the material to be rolled 13 is controlled so that the optimum linear velocity ratio R is obtained in advance.
[0029]
The speed of the material 13 to be rolled in the actual operation is controlled, for example, by controlling the rotation speed of the drive motor 10 of the final finishing mill 5.
That is, in the actual operation, the material 13 to be rolled between the finishing mill 4 and the final finishing mill 5 until the tip of the material 13 exits the finishing mill 4 and enters the final finishing mill 5. Is measured by the linear velocity meter 14, and the measured top velocity V 0 ′ is taken into the main controller 12.
Next, using the measured value V0 ′ and the optimum linear speed ratio R among the linear speed ratios stored in the storage unit 22, the target middle unit speed V1 ′ is calculated by the arithmetic unit 23 using the above equation ( It is calculated by 2).
[0030]
Before the leading end of the material 13 to be rolled enters the final finishing mill 5, the number of revolutions of the drive motor 10 of the final rolling mill 5 is controlled so that the middle part speed of the material 13 becomes the target speed. Control is performed so as to be the middle portion speed V1 '.
FIG. 7 shows the relationship between the linear speed between the finishing mill 4 and the final finishing mill 5 and the peripheral speed Vr of the first stand roll of the final finishing mill 5 when the linear speed ratio R is constant. FIG. The relationship in FIG. 7 is obtained in advance by an experiment or the like. 7 is stored in the storage unit 22.
[0031]
The rotation speed control of the final finishing mill 5 is performed using the relationship of FIG.
That is, the roll peripheral speed Vr for obtaining the middle portion linear speed V1 at the optimum linear speed ratio R is obtained from FIG. When the roll peripheral speed Vr is obtained, the motor rotation speed M of the final finishing mill 5 can be determined from the speed increase ratio G and the roll diameter D as in the following equation (3). Such arithmetic processing is performed by the arithmetic means 23.
M = Vr / (G × π × D) (3)
In this embodiment, since the final finishing mill 5 is composed of a sizing mill and has a plurality of work rolls, the roll peripheral speed Vr and the roll diameter D are those of the roll of the first stand.
[0032]
In the above method, after measuring the speed of the tip of the material 13 to be rolled, it is possible to perform a preset for controlling the number of revolutions of the final rolling / finishing mill 5 before the tip of the material 13 to be bitten into the final finishing mill 5. is there. Also, with respect to tension fluctuation during wire rolling due to skid marks or the like generated in the heating furnace, feedback control is performed so that the momentary speed during rolling becomes the target speed V1 calculated from the linear speed ratio R. It is also possible.
So far, the relationship between the linear speed ratio R and the roll peripheral speed Vr under a certain rolling condition without considering the fluctuation has been described. However, these relationships are based on the product size (pass schedule), the output of the finishing mill 4, and the like. Since it depends on the side wire diameter dm and the roll gap S of the first stand of the final finishing mill 5, it is necessary to control in consideration of these variations.
[0033]
FIG. 8 is a graph showing the relationship between the variation ΔS of the roll gap S of the first stand of the final finishing mill 5 and the variation Δd of the product width dimension.
FIG. 9 shows the variation ΔS of the roast gap S of the first stand of the final finishing mill 5 and the peripheral speed of the first stand of the final finishing mill 5 when the value of the linear speed ratio R is constant. 6 shows the relationship between Vr fluctuation amounts ΔVr.
8 and 9 are obtained in advance by experiments or the like, and are stored in the storage unit 22.
[0034]
From the relationship shown in FIG. 8 and FIG. 9, even when the roll gap S is changed during or before rolling in order to adjust the product dimension d, the target linear velocity ratio R value is set. Roll peripheral speed Vr can be determined.
That is, the product dimension d is measured by the second dimension measuring device 19, and the product width dimension variation Δd is obtained. It is determined whether or not the variation Δd is out of the allowable value. If it is out of the allowable range, the roll gap adjustment amount ΔS for obtaining the target size is obtained from the relationship shown in FIG. Then, the roll gap S is adjusted by the reduction device 11 based on the obtained adjustment amount ΔS. At the same time, from the relationship of FIG. 9, a roll peripheral speed Vr that does not generate the tension generated by adjusting the roll gap S is obtained. Then, the rotational speed M of the drive motor 10 of the final finishing mill 5 is controlled based on the above equation (3) so that the obtained Vr is obtained.
[0035]
These processes are performed by the main controller 12.
By performing such control, in the next material of the product shown in FIG. 10, a highly accurate dimension can be obtained over the entire length as shown in FIG.
The above description is an attempt to control the next material, but when applied during the rolling in the rolling shown in FIG. 10, the result is as shown in FIG.
FIG. 13 shows the relationship between the variation Δdm of the exit side wire diameter dm of the finish rolling mill 4 and the product dimension variation Δd.
[0036]
FIG. 14 shows the relationship between the roll gap adjustment amount of the first stand of the finish rolling mill 4 and the exit side wire diameter variation Δdm of the finish rolling mill.
FIG. 15 shows the variation Δdm of the exit side wire diameter dm and the variation of the roll peripheral speed Vr of the first stand of the final finishing mill 5 when the value of the linear speed ratio R is constant. Shows the relationship.
These relationships shown in FIGS. 13 to 15 are obtained in advance by experiments or the like, and are stored in the storage unit 22. These data can be learned in actual operation and can be updated to optimal data.
[0037]
From the relationship shown in FIGS. 13 to 15, even if the exit side wire diameter dm of the finishing mill 4 is changed during or before rolling in order to adjust the product dimension d, the target linear velocity The roll peripheral speed Vr for setting the R value of the ratio can be determined.
That is, the diameter dm of the exit side wire rod of the finishing mill 4 is measured by the first dimension measuring device 15, and the fluctuation amount is obtained as Δdm. When the amount of variation is out of the allowable value from the relationship of FIG. 13, the adjustment amount Δdm is obtained. The roll gap of the first stand of the finish rolling mill 4 is adjusted based on the relationship shown in FIG.
[0038]
At the same time as the adjustment of the roll gap, from the relationship shown in FIG. 15, the roll circumferential speed Vr that does not generate the tension generated by adjusting the roll gap (diameter of the wire on the exit side of the finish rolling mill) of the first stand of the finishing mill 4 is Desired. Then, the rotational speed M of the drive motor 10 of the final finishing mill 5 is controlled based on the above equation (3) so that the obtained Vr is obtained.
Experiments have shown that the R value of the optimum linear velocity ratio has no cobbles and can reduce the dimensional fluctuation of the bottom portion when it is in the range of 0.01% to 5%.
[0039]
【Example】
FIGS. 16 and 17 show the measurement results of the dimensions over the entire length of the product when an experiment was performed under the following conditions in the case of no conventional control and the case of the present invention, respectively.
"Experiment conditions"
Product steel type: JIS SCM435
Wire speed: 120m / s
Wire diameter: φ5.5
Finishing mill exit side wire diameter: φ7.0
Final stand rolling mill first stand roll gap: 1.0mm
Final finishing mill entry temperature: 900 ° C
In this embodiment, first, setting is performed using the stored previous rolling condition data, the speed V0 of the top portion of the material to be rolled is measured, and the target middle portion speed V1 'is obtained from the equation (2) based on the speed. The calculation of the roll peripheral speed of the first stand roll of the mill is performed based on FIG. 7 and the motor speed of the final finishing mill is calculated based on the equation (3). The number of revolutions of the final finishing mill motor was adjusted so that the number of revolutions became equal to the number of revolutions. Thereafter, the product width dimension variation Δd was measured, and the variation was controlled so as to fall within an allowable value.
[0040]
According to the method of the present invention, as shown in FIG. 17, there is no dimensional change over the entire length of the product, and the product is rolled to the target size.
Note that the present invention is not limited to the above embodiment.
[0041]
【The invention's effect】
According to the present invention, there is no dimensional variation over the entire length of the product, and high-precision dimensional control is possible.
[Brief description of the drawings]
FIG. 1 is an overall view of a rolling line for carrying out the method of the present invention.
FIG. 2 is a graph showing a change in width of the entire product length when tension is applied between a finishing mill and a final finishing mill.
FIG. 3 is a graph showing a width dimension change of the entire product length when there is no tension between a finishing mill and a final finishing mill.
FIG. 4 is a detailed view between the finishing mill and the final finishing mill in FIG. 1;
FIG. 5 is a graph showing a change in speed between a finish rolling mill and a final finishing rolling mill from a leading end to a trailing end of a wire rod.
FIG. 6 is a graph showing a relationship between a linear velocity ratio R and a width dimension variation amount at a product end portion;
FIG. 7 is a graph showing the relationship between the wire speed between the finishing mill and the final finishing mill and the peripheral speed of the first stand of the final finishing mill when the R value is constant.
FIG. 8 is a graph showing a relationship between a variation in roll gap of a first stand of a final finishing mill and a variation in product width dimension.
FIG. 9 is a graph showing the relationship between the roll gap variation of the first stand of the final finishing mill and the circumferential speed variation of the first stand roll of the final finishing mill.
FIG. 10 is a graph showing a dimensional change in the entire length of the product when only the tension is adjusted without adjusting the roll gap in the method of the present invention.
FIG. 11 is a graph showing a dimensional change in the entire length of the product when the adjustment of the roll gap and the adjustment of the tension are performed in the method of the present invention.
FIG. 12 is a graph showing a dimensional change in the entire product length when the method of the present invention is applied to one rolled material.
FIG. 13 is a graph showing the relationship between the variation in wire diameter on the exit side of the finishing mill and the variation in product width dimension.
FIG. 14 is a graph showing a relationship between a roll gap adjustment amount of a first stand of a finish rolling mill and a wire diameter variation Δdm on the exit side of the finish rolling mill.
FIG. 15 is a graph showing the relationship between the wire diameter variation on the exit side of the finishing mill and the roll peripheral speed variation of the first stand of the final finishing mill.
FIG. 16 is a graph showing a width dimension over the entire length of a product subjected to rolling by a conventional method.
FIG. 17 is a graph showing a width dimension of a product to which the method of the present invention has been applied over the entire length.
[Explanation of symbols]
4 Finish rolling mill
5 Final finishing mill
10 Drive motor
11 Roll-down device
12 Main controller
13 Rolled material
14 Moving speed measuring device

Claims (6)

In a method of rolling a steel bar to roll a material to be rolled on a rolling line including a finish rolling mill and a final finishing mill on the downstream side thereof,
The top speed of the material to be rolled between the finishing mill and the final finishing mill until the tip of the material to be rolled out of the finishing mill and entering the final finishing mill is V0, When the middle part speed of the material to be rolled until the trailing end of the rolled material passes through the finishing mill is V1, the linear speed ratio R is such that the dimensions are uniform over the entire length of the product after leaving the final finishing mill. The value of {(V1-V0) / V0} × 100 is obtained in advance,
In the actual operation, the top portion speed is measured, and when the measured value is V0 ′, the target middle portion speed V1 ′ is calculated using the value of the linear speed ratio R obtained in advance,
V1 ′ = V0 ′ + V0 ′ × R / 100
Before the leading end of the material to be rolled enters the final finishing mill, the rotation speed of the drive motor of the final finishing mill is controlled so that the middle part speed of the material to be rolled becomes the target middle part speed V1 ′. And a method for rolling a steel bar. In a method of rolling a steel bar to roll a material to be rolled on a rolling line including a finish rolling mill and a final finishing mill on the downstream side thereof,
The top speed of the material to be rolled between the finishing mill and the final finishing mill until the tip of the material to be rolled out of the finishing mill and entering the final finishing mill is V0, When the middle part speed of the material to be rolled until the trailing end of the rolled material passes through the finishing mill is V1, the linear speed ratio R is such that the dimensions are uniform over the entire length of the product after leaving the final finishing mill. The value of {(V1-V0) / V0} × 100 is obtained in advance,
In the actual operation, the top portion speed is measured, and when the measured value is V0 ′, the target middle portion speed V1 ′ is calculated using the value of the linear speed ratio R obtained in advance,
V1 ′ = V0 ′ + V0 ′ × R / 100
While the final finish rolling mill is rolling the material to be rolled, the drive speed of the drive motor of the final finish rolling mill is controlled so that the middle speed of the material to be rolled becomes the target middle speed V1 ′. A method of rolling a steel bar, characterized by controlling. The relationship between the roll peripheral speed Vr of the final finishing mill at the linear speed ratio R and the speed V1 of the material to be rolled is determined in advance, and based on this relationship, the target middle portion speed V1 'is obtained. 3. The method according to claim 1, wherein the number of rotations of a drive motor of the final finishing mill is controlled. The relationship between the roll gap variation ΔS and the product dimension variation Δd of the final finishing mill and the relationship between the roll gap variation ΔS and the roll peripheral speed variation ΔVr at the linear velocity ratio R are determined in advance, and these relationships are used as a basis. In addition, the roll gap of the final finish rolling mill is controlled so that the product dimension becomes an appropriate dimension, and the driving motor rotation speed of the final finishing mill is controlled so that the target middle section speed V1 ′ is achieved. 4. The method of rolling a steel bar according to claim 3, wherein: The relationship between the exit side dimension variation Δdm of the finishing mill and the product dimension variation Δd, and the relationship between the dimension variation Δdm at the linear speed ratio R and the roll peripheral speed variation ΔVr of the final finishing mill are previously determined. Based on these relations, based on these relationships, the exit side dimension dm of the finish rolling mill is controlled so that the product dimension is an appropriate dimension, and the final finish rolling is performed so that the target middle section speed V1 'is achieved. 4. The method according to claim 3, wherein the number of revolutions of the drive motor of the mill is controlled. The method according to claim 1 or 2, wherein the linear speed ratio (R) is 0.1 to 5%.

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