JPS60121015A - Correcting method of interstand tension in tandem rolling of bar material - Google Patents

Abstract

PURPOSE:To correct a titled tension at low cost while maintaining the dimensions and quality of a product in high grade by correcting the number of revolutions of a rolling roll or a roll gap so as to offset the deviation of each interstand tension, obtained from the tension change, etc., only at the final interstand of an optional rolling line, from a target tension. CONSTITUTION:In a tandem rolling for continuously rolling a bar material by plural stands, by previously setting an interstand target tension; the interstand tension ia corrected by the following method. That is, the tension change only at the final stand of a rolling line which is optionally chosen among a rough rolling line, an intermediate rolling line, and a finish one, or the change of width dimension at a point of a prescribed distance away from the tail end of the bar material to be rolled by the line in question, is detected. And the deviation of each interstand tension from said target tension is obtained basing on the data of these changes and previously obtained influence factors. Next, the number of revolutions of a rolling roll or a roll gap is corrected so as to offset the deviated tension, thereby correcting an interstand tension in a tandem rolling of bar material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to tandem rolling in which rolling is performed continuously by inserting stripes into a plurality of stands, and more particularly, to a method for correcting inter-stand tension of rolled material. Regarding.

[Background of the invention]

As a billet of an appropriate length heated in a heating furnace is sequentially passed through a rough rolling train, an intermediate rolling train, or a finishing rolling train, the cross-sectional area is reduced and the speed gradually increases. It is drawn into a wire rod having a predetermined size and shape. In this rolling operation, the dimensional quality of the rods in the water varies depending on the tension between the stands, which causes dimensional errors, so the tension between the stands should be set to zero tension or to a small constant tension (or compression) for the sake of operability. required to be maintained.

By the way, when controlling tension, the difference between the predetermined target tension and the actual tension is the control value, so
The tension actually occurring must be detected by some kind of detection means. Conventionally, this actual tension has generally been measured with a tension meter installed between each stand. However, this requires a large number of tensiometers, and they must be installed between the stands of a rolling mill with a complex mechanism, resulting in significant space constraints or, conversely, limiting the number of tension meters. There are problems and maintenance issues.

Therefore, in order to solve these problems and achieve the automation required by the times, indirect tension control methods using computers have been proposed.

And in fact, the latest t'A 22 #ii based on this method
Some places are still operating. However, it is true that it is functionally superior to conventional existing equipment, or that new equipment requires a large amount of capital investment and is difficult to adapt to the current industrial environment. Therefore, the main challenge now is how to adapt to the current situation the conflicting demands of suppressing new investment as much as possible in order to maintain competitiveness and obtaining high quality products at low cost.

[Purpose of the invention]

The main object of the present invention is to provide a method for adjusting the tension between stands in tandem rolling, which can maintain high dimensional quality of the product by skillfully controlling the tension so as to reduce the cost rather than increasing the cost. .

Another objective is to eliminate the need for multiple tension meters by applying a method different from the conventional method to existing mills that previously used multiple tension meters, and to eliminate the complexity of maintenance and management. It is to be.

In particular, where each stand has a common ground motion and a constant gear ratio,
That is, in the case of block rolling, it is impossible to adjust the rotation speed in each stand in order to offset the tension deviation, and it is necessary to adjust the tension using the rolling gap of the rolling rolls.
Another object of the present invention is to provide a tension correction method that can effectively deal with this block rolling.

[Summary of the invention]

Therefore, in tandem rolling where the target tension between the stands is determined in advance and the dye is impregnated into a plurality of stands and the rolling is carried out continuously, the present invention aims to solve the problem of the final rolling row of any one of the rough rolling row, intermediate or final rolling row. Examine the tension change only between the stands, or examine the width dimension change at a predetermined distance from the tail end of the dye rolled in the rolling row, and use the above tension change data or the width dimension change data in advance. Based on the influence coefficient, the deviation from the target tension described in 1. between each stand of the rolling train is determined, and the number of rotations of the rolling rolls or the rolling gap of the rolling rolls is adjusted to offset this deviation tension. This is a basic feature.

Practically speaking, when the rolling mill is in a steady state where it is wedged in the stands, the actual tension that is actually acting will cause a deviation (or residual difference) from the predetermined target tension between the stands. The key is to grasp whether there are any. In tandem rolling of dyes, if tension exists between stands, when the rolling tail end passes through that stand, the tension between the stands is released and propagates to the downstream stands. There is a certain relationship between the tension released at this time and the tension propagating downstream, and this relationship can be determined in advance as an influence coefficient by a pass schedule. Therefore, the change in tension between the final stands of the rolling train is investigated and the position (or region) of the change is determined.
By analyzing this, the values of the tension between the stands where tension existed and the deviation tension can be determined by calculation. in this case,
It is sufficient to install one tension meter between the final stands.

In addition, as the tail ends of the rolling train pass through the stands one after another, a change in tension propagates between the downstream stands, and in response to this change in tension, the width dimension of the rolled strip material changes, and the width of the rolled strip material changes.
The inter-stand residual tension can be calculated from the change in the width dimension in the water, ie, the convergence level difference, using the influence coefficient between the width dimension and the tension. In this case, a tension meter is not required, and it is sufficient to simply provide a width gauge.

〔Example〕

Hereinafter, features of the present invention will be specifically explained along with other features based on embodiments illustrated in the accompanying drawings.

First, a general example will be explained. The rolling row consists of a number of stands, numbered 1, 2, etc., in order from upstream to downstream where the dye flows. ...fi+..., k are given, and the number l(1+ 2 +...).

The stand is identified by k).

The final stand of this rolling row is stand k (-stand), and the distance between the final stands is between stand (k-1) and stand K. An example of investigating width dimension changes will be described.

In Kundem rolling from stand l to stand k, a width dimension gauge is installed on the strip exit side of the stand, which is the final stand of the rolling row under consideration, to measure the bottom of the rolled strip after pass k, that is, the rolling width. The change in width over a predetermined distance from the tail end of the strip H is measured. Width dimension data can be obtained using a width dimension meter.

As shown in the flowchart of FIG. 1, next, the width dimension between (Li - I Li) extending from the tail end of the strip H extending in L between the distance of Lil and the distance of I - i is calculated. Δ is included.

Li=fli,・〃 χj (i=01L2+..., -1) ......(1) 1-=++1 Ll: Influence length on which the width of the tail of the dye changes βi: Stand mill ( i+i) distance between stands, where β. represents the total length of the build.

χ1: The rate at which the strip is stretched in a pass in stand i, Ai where Ai is the cross-sectional area of the strip in stand i.

From this, the amount of change in the width dimension δBi (i=1.2°...,
−1) can be calculated using the following equation (2).

δ13i = Bi B14-1 (2) This means that when the ridge leaves the first stand i, the width dimension of the length Li from the tail end of the ridge after k passes is , stand 1~(=+1), (i-z,)~(i+2L...
..., it changes under the influence of the tension between (k-2) and (k-1), and the influence on the width of the rear tension J is sufficiently large compared to that of the front tension. The focus is on Here, since the width dimension measurement value captures the change in width rather than the absolute value, high resolution can be obtained.

In a preferred embodiment, the next step is to compare the dimensional tolerance ε within one of the rolled strips. That is, δBi
It is checked whether the absolute value of is less than or equal to ε defined by the width dimension tolerance within one dye. If it is less than ε, rolling can be continued in that state. 1δBi l
>ε means that the inter-stand tension deviates considerably from the predetermined target inter-stand tension due to cracking, and it is necessary to correct the inter-stand tension. When correction is required, the inter-stand tension deviation δFOi is determined at a steady state with no sudden fluctuations when the rack is caught in the stand.

Now, when l leaves stand i, the width dimension of the length of Li from the tailmost end of the strip after k passes is stand i~(i+
1), (i+1)~(i+2),...
, (k-2) to (k-1) changes under the influence of tension. This can be expressed as the following equation (3).

Here, δBi: The amount of change in the dye width dimension on the exit side of the stand before and after the i-stand butt is removed.

δFii: The amount of change in tension between the i and (1+1) stands when the buttocks are exposed.

βi: Influence coefficient of the above tension change amount on the width of the strip on the exit side of the stand.

Next, when the butt of one stand is removed, the amount of change in the tension between j~(l+1) stands δFt j is the tension between i~(l+1) stands δFiiK″A, and the relationship is expressed by the following equation.

Amount of tension change between j~(l+1) stands when l stand buttocks are exposed.

αij; Influence coefficient of the inter-stand tension between i and (1+1) on the inter-stand tension between j and (l+1) downstream of l stand.

On the other hand, δFii in equations (3) and (4) is δI”oi(
It can be calculated as shown in Equation (5) using (i to (i+1) steady deviation tension between stands at the time of biting) and δF 11.

Therefore, by tracking Li in advance, determining δBi using a width dimension meter, and having an influence coefficient αlJ+βl, δFol can be determined, and the correction amount δF for the target tension F.
i is expressed as δFi:Fi0−δFol. The correction amount δF1 thus obtained is applied to a relational expression described later, and the correction amount of the roll rotation speed or rolling gap of each stand i is determined.

FIG. 2 shows a more specific explanatory diagram, taking as an example the case of eight stands.

Considering the time when the butt of the strip of #1 stand is exposed, the shadow sound length (L
l - L2:) IIIA 'i with the preceding part for K
Since the J-method step difference δB1 is taken into account, δF11 is determined by the influence coefficient β1. Also, δF11−−δ”01
Therefore, δFo1 is a circle.

δ131-β1”δF11 ・・・ (6) # 1 in r+ diagram by δF11 and influence coefficients α12 to α17
Horizontal component δF12 in the blank column. δF13.・・・・・・、
δF17 is observed.

Next, from the obtained width dimension step difference δB2 and influence coefficient β2, δ
F22 is found, δB2-β2・δF22 ・・・・・・(8) δF2
2 is δF22--(δF02+δF12) =-= (9
1, since δF12 is determined by equation (7), δFO2 can be determined from equation (9).

Next, since δF33 is given by the following equation, δF3a−-
(δFo3+δF13+δF23)=-(IO, on the other hand,
δF33 is determined by the width dimension step δB3 and the influence coefficient β3, δF33-β3・δB3 · Old... (12), and δF13 and δF23 are determined by equations (7) and (1o). Therefore, δI"03 is full.

Repeat this process in the same way, and δF77 is calculated by the following formula % Formula % (13) On the other hand, δF77 is determined by the width dimension step δB7 and the number of affected surfaces β7, δB7−β7・δF77 ... the peak (15), ]4) δFii(i~1.2...) in formula.

6) has already been considered before that, so the influence coefficient α1
7, it can be seen as follows.

Based on the above, the deviation of the target tension when the strip is inserted, that is, the normal deviation j of the tension force δF between each stand i ~ (i + 1)
oIC1-1, 2, Kawa, 7) was found.

Nao, the influence coefficients αij and βi in item 1 are coefficients set in advance through simulation or trial experimentation.

Here, when there is tension between the upstream stands and the tail of the dye passes through the stand, the effect of the tension between the most downstream stands is that the further upstream the stand is, the smaller the effect is, and vice versa. Considering that the influence of the deviation tension between the downstream stands has a large influence on the final product width dimension,
For example, α1j(l-1,2,...M: j=i+1
, i+2 ,...M+1:M≦-3)'0
Even if you perform the above calculation, you can still reach your goal.

Next, the tension change only between the final stands is investigated, and the target tension p between each stand i~(i+1) is determined based on the data on this tension J change and a predetermined influence coefficient.
A method for calculating the deviation δFoi (i=1.2° . . . , 7) from iO will be explained.

Note that in this method, the same symbols and symbols as illustrated in FIG. 2 are used. In addition, this method obtains the entire tension change as a result and then analyzes it to calculate δ
Foi can be set, but here we will describe an example in which δFoi is set sequentially along the flow of the threads IJ' to Z, that is, as the tail ends successively exit from the stand 1, in order to make it easier to separate.

As shown in FIG. 3, one tension meter is installed between stands #7 and #8, which are the final stands. This tension meter measures the change in tension of the rolled strip Z between stands #7 and #8. It may be measured continuously, but at least the tail end of dye Z is measured at each stand 1 (i-1, 2, 3, 4, 5
, 6, 7)), monitor the change in tension when it comes out (when it comes out).

That is, as shown in FIG. 3, the tension change δF17 when #1 stand is empty, δF27 when #2 stand is empty, '
δF37 at 3 stand/missing,...
The data of δF77 at #7 stand/miss is shown.

When #1 stand is missing, δF17 is observed, so the following formula (
17) δF11 is determined by (same as equation (7) above).

δFll−δF17/α17 ・・・・・・C17) δ
F01 is according to equation (18), and δF12 to δF16 are (
17').

δFo1=-δF11...Old...(18) # Next, from δF27 obtained when missing 2 stands, (1
δF22 is calculated by equation (9) (same as equation (10) above).

δ■722−δF27/α27 ・・・・・・・・・(
19) δFo2 is (20
) equation (in the system, δFO2=−(δ1?22+δF12) −−−−−
-・-・(20) On the other hand, since δF12 has already been determined by the above equation (17), δFO2 is determined.

Then, using δF22 calculated in equation (19), the following (1
9') δF23・δF24・δF25・δF2
6 is seen.

Next, tension ashing data δF37 when #3 stand is exposed
Therefore, δF33 is determined.

δF33-δF37/α37 ・・・・・・・・・ (2
1) δFo3 is determined by the following equation.

δFo 3−- (δF33+δF23+δF13)
=・At the same time as (22), δF34. δF35. δF36 is disputed.

Similarly, by repeating the above calculation, δFO6 can be obtained from the data δF67 at the time of #6 stand/miss by the following equation (23).

δF06=-(δF66+δF56+δF46+61?
36+δF26+δ”16)・・・・・・・・・(23
) Finally, when the data δF77 when stand #7 is removed is obtained, the steady deviation tension between the final stands δJ・o7 is '
(24) is used as a component. δF17~δF6
7 is a take that has already been obtained.

The steady deviation tension δFOi (+ = 1.2
......, all 7) were obtained.

Next, the constant of each rolling stand is actually corrected by 11 using the steady deviation tension δFo1 obtained by examining the width dimension change or the tension change as described above. That is, the number of rotations of the rolling rolls or the rolling clearance of the rolling rolls is adjusted by one point so as to offset the deviation tension.

The rotational speed of the mill roll is corrected by, for example, using the following equation (25) to correct the equivalent circumferential speed of the mill roll.

(J, Nicho Eihaku) ■ = Roll circumferential speed ΔVx<4 of 1 meter at predetermined target tension (or no RO・i tension): Speed correction amount 1・'l Hi to (i+1) between stands Tension (tension at exit side of stand i) M: Influence coefficient matrix as follows... (26) Here, K[; (l=l l 2,...) -1): Influence coefficient that forward tension has on forward and backward movement.

Kbi (i=1.2..., -1): Influence coefficient that rearward tension exerts on forward and backward movement.

A term of 0 in this enrichment coefficient matrix M indicates that there is mutual interference between adjacent tensions in the inter-stand tension F, but there is no other mutual interference. The influence 1 series matrix M is usually held in advance in the form of a table according to the rolling conditions.

When correcting by the rolling gap, see (25) above.

Using the speed correction amount ΔvR1 determined by the equation (26), the rolling gap ΔSi is corrected using the relational expression of the following equation (27).

ΔvR1−Di・ΔSi (27) Here, Dl is the speed correction coefficient for the rolling gap given by the formula (28).
: Cross-sectional area of rolling dye in stand i.

[1: Rolling village at each stand i advanced rate.

vi: Average roll speed corresponding to advance rate fi.

a[ -: Coefficient for rolling gap of advance rate, S to 8 −: Coefficient of the cross-sectional area relative to the rolling gap.

It is determined by the rolling method of the S-roll and can be kept in advance in the form of a table.

Δ”+ ('=1 + 2 +...
. . , k) are applied to each stand lid (i=1.2.-. . . , k) off-road, and are individually set for correction. However, the roll gap at the final stand is restricted by the product dimensions, so from now on, the roll gap at the first stand will be corrected.

This method of adjusting the rolling gap is particularly useful when it is impossible to adjust the rotation speed of each stand individually, that is, in rolling where each lid 2/door is driven co-ordinately and the gear ratio is constant (flock rolling). It is understood that this is a useful method.

As described above, in the present invention, there are two methods for calculating the steady cylinder 1 difference from the target tension, and two methods for correcting the settings to cancel out the steady deviation, for a total of 4 methods. This method includes the following methods. In any case, it concerns only the last stand of any rolling train, and the steady-state deviation tension can be determined by simply installing a width measuring needle or a single tension gauge and examining the width or tension change data. Tension can be easily corrected to maintain good dimensional accuracy of the product.

The influence coefficients and other coefficients set in advance are held as data files as influence coefficients and other coefficients for each rolling method of the rolling pass and schedule. An operator can index these coefficients and obtain corrected data through predetermined calculations or graphical searches. Further, it is also possible to convert the change data obtained from the measuring instrument into numerical data and input it manually into a computer (regardless of whether it is large or small) to obtain desired correction data. In an advanced embodiment, the sensor of the width measuring needle or tension meter is connected to the computer for the rolling side 011, and the sensor output by one-temperature synchronization is stored in the coefficient group (chifulized) stored in advance in the storage means. It is also possible to perform processing based on a predetermined software program including a predetermined calculation formula, output a command to the actuator, and automatically correct the inter-stand tension.

〔effect〕

As is clear from the above explanation, according to the present invention, even in existing tandem rolling mills that have been used conventionally, changes in the width dimension only when the tension is changed between the final stands or when the tail end is removed are monitored. By just doing this, the tension between each stand can be easily adjusted, and the dimensional accuracy of the finished product can be maintained at a high level without incurring any additional costs. It can effectively cope with such rolling methods, and has excellent industrial applications.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of an embodiment according to the present invention, FIG. 2 is an explanatory diagram illustrating this embodiment in more detail, and FIG. 3 is an explanatory diagram specifically illustrating another embodiment. . Z...Rolled strip, #1 to #8...
...Rolling stand number from upstream to downstream, #
8...Final stand, #7~#8...
Between the final stands. Patent applicant Kobe Steel, Ltd.

Claims (2)

[Claims] (1) In tandem rolling, where the target tension between stands is determined in advance and the strip is rolled continuously between multiple stands, the tension changes only between the last stand of a given rolling train or the rolling process occurs in that rolling train. The change in width dimension at a predetermined distance from the tail end of the strip is examined, and the target value is determined between each stand of the rolling train based on the data on the tension change or the data on the width change and a predetermined total influence coefficient. A method for correcting tension between stands in tandem rolling of strips, characterized in that the deviation from the tension is detected and the rotational speed of the rolling rolls or the rolling gap of the rolling rolls is corrected so as to offset the deviation tension. (2) Block rolling is carried out in which the target tension between the stands is determined in advance and continuous rolling is performed by inserting the strips into multiple stands, and each stand is commonly driven and the gear ratio is constant. In this case, examine the change in tension only between the final stands of any rolling train or the change in width at a predetermined distance from the tail or end of the strip rolled in the rolling train, and check the data on the change in tension or the change in width. The deviation from the target tension between each stand of the rolling train is calculated based on the data and the predetermined influence coefficient, and the rolling clearance of the rolling rolls is corrected to offset this deviation tension. A method for correcting tension between stands in grained tandem rolling.