JPH0747172B2 - Roll profile detection method for sheet rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to strip thickness accuracy and strip crown in strip rolling.
The present invention relates to a method for estimating a work roll profile during a rolling operation, which has a significant influence on the shape.

[Conventional technology]

Since the work roll profile of the strip rolling mill shows complicated changes due to wear and thermal expansion during the rolling operation, it is not possible to determine the operating conditions of the rolling mill by using the data of the work roll profile at the time of known roll incorporation. An error resulting from the estimation error of the work roll profile will occur in the plate thickness and the plate crown / shape. Therefore, in order to avoid such an error, it is necessary to estimate the work roll profile. The conventional technique for performing this estimation is as follows.
There are types.

A method of calculating and estimating the work roll profile at any point during operation from the rolling operation conditions using the roll wear calculation formula and roll thermal expansion calculation formula.

A method of directly measuring the work roll profile using a contact or non-contact displacement meter.

[Problems to be solved by the invention]

The method of using the roll wear calculation formula and the roll thermal expansion calculation formula of the above conventional method, in the state of the art, the work roll profile is actually measured by some detection means, and if the work of correcting the calculated value is not performed, the estimation accuracy It is difficult to put this into practical use.

Further, the conventional method is an excellent method in that the work roll profile is directly measured, but since these measuring devices are generally expensive and are precision measuring devices used in a bad environment, their maintenance is difficult. In addition, it requires a great deal of manpower and cost to maintain the accuracy, and also becomes a factor that deteriorates the workability of the normal rolling work such as the work roll change.

Then, this invention aims at measuring a work roll profile, without using a specialized measuring device like the conventional method.

[Means for Solving Problems and Their Actions]

In order to achieve the above object, in the present invention, in the plate rolling machine, during the interruption period of the rolling operation, the rolling device is operated to bring the upper and lower work rolls into contact with each other, and the rolling set value obtained by further tightening Characterized by calculating and calculating the amount of change in the work roll profile from the time of incorporation by comparing and analyzing the relationship with the rolling reaction force measurement value by the rolling reaction force measuring device and the same relationship when the work roll was incorporated. The roll profile detection method of the plate rolling machine is used. According to another aspect of the present invention, in a plate rolling machine having a roll axial shift function, two or more positions of the shiftable rolls are taken during a rolling operation interruption period, and a rolling down device is operated to move the roll up and down. By incorporating and comparing the relationship between the rolling reduction force measured by the rolling reaction force measuring device and the rolling reduction force setting value obtained by bringing the work roll into contact and tightening it, and comparing it with the same relationship when incorporating the work roll. The above object is achieved by using a roll profile detecting method for a plate rolling machine, which is characterized in that a change amount of a work roll profile from time to time is calculated and calculated.

Among the above-mentioned means, there are two types of reduction devices, an electric reduction device using a reduction screw and a hydraulic reduction device.
In any case, it is a device that is always included in the plate rolling machine. Further, the rolling reaction force measuring device is currently provided in most rolling mills, and is utilized for setting calculation of the rolling mill or automatic strip thickness control during rolling. As mentioned above,
The apparatus required for the present invention is not special one, and it is almost included in an ordinary plate rolling machine. The interruption period of the rolling work is a period from the end of rolling one material to the start of rolling of the next material in the rolling mill, and it depends on the type of rolling mill and the production amount, but is from several seconds to It is usually several tens of seconds. In the case of the hydraulic pressure reduction system having a quick response, it is possible to bring the upper and lower work rolls into contact with each other and further tighten them (hereinafter, this is referred to as kiss roll tightening) even during the interruption period of several seconds. With a rolling mill equipped only with an electric rolling down device,
Within the normal rolling suspension period, tighten the kiss roll,
If data cannot be collected, the rolling interruption period may be extended only at that time. Since it is not necessary to perform this work for each rolled material, it is possible to suppress the decrease in the production amount due to (extending the rolling interruption period) to such an extent that it does not pose a problem.

FIG. 1 shows the relationship between the rolling reduction set value and the rolling reaction force measured value obtained as a result of operating the rolling reduction device and tightening the kiss roll during the interruption period of the rolling operation. Normally, the zero point of the reduction set value is determined when the kiss roll is tightened immediately after the roll is reassembled and the rolling reaction force matches the predetermined zero point adjustment load P _o , and the roll gap opening direction is set to the positive of the reduction set value. Since it is determined as the direction of, the drawing is drawn according to this convention also in FIG. In Fig. 1, data 1 is the data collected immediately after the roll change,
It passes through the point of reduction set value g = 0 and rolling load P = P _o . Data 2 or 3 shows data collected during the interruption period after the rolling operation was carried out for a while after the rolls were recombined. When the work roll is expanded as a whole, a high rolling reaction force is obtained for the same reduction set value as shown in data 2, and when the work roll diameter is reduced due to wear or the like, data 3 Thus, a small rolling reaction force can be obtained for the same reduction set value.

By the way, as shown in FIG. 1, in the low load region, there is a portion where the data immediately after roll reassignment and the data after rolling are not parallel. This is because, in the low load region, the rolls are not generally in contact with each other in front of the effective cylinder length, and the contact range between the rolls that influences the mill rigidity in that state is affected by the roll profile at that time. This is because. On the other hand, in the high load region, there is a portion where the data immediately after roll re-rolling and the data after rolling are almost parallel, but in this region each roll is in contact with the entire effective cylinder length. Is judged. Strictly speaking, changes in the tightening data are also affected by changes in the profile of the reinforcing rolls or intermediate rolls, so these changes in profile are also taken into consideration by the calculation formula created in advance. Embodiments are also possible. However, in general, the profile change of the reinforcing roll or the intermediate roll during the continuous use period of one set of work rolls is very small compared to the work roll profile change. Changes in the profile shall be ignored.

Now, in the high load area as described above, if a portion where the data immediately after roll change and the data after rolling are parallel is obtained, the difference Δg (current value-roll) for the same rolling reaction force in that area Immediately after reclassification). If the rolling reaction force is the same, it is considered that the average contact load between the rolls is the same and the average amount of deformation is also the same. Therefore, Δg reflects the change ▲ ▼ in the average radius of the work rolls. Assuming that the profile changes of As a result, the value ▲ ▼ obtained by averaging the change in the work roll radius over the entire effective cylinder length is obtained.

Next, the method of obtaining the distribution of the radius change ΔR in the cylinder length direction, that is, the work roll profile from ▲ ▼ can be roughly classified into the following two methods.

Assuming the pattern of the work roll profile or obtaining it by calculation, from the obtained ΔR,
Calculate ΔR at each location.

The roll deformation of the rolling mill is simulated, and a work roll profile that can explain the behavior of the rolling reaction force-the reduction set value in the low load region of FIG. 1 is calculated.

Specifically, various modes such as a method of combining the above can be considered, which will be described in detail in the section of Examples.

A rolling mill having a roll axial shifting function means a multi-rolling mill having four or more rolls having a work roll shift, an intermediate roll shift, or a reinforcing roll shift function.
It also includes a rolling mill in which the sleeve provided on the reinforcing roll can be shifted in the axial direction of the roll. In the case of such a rolling mill,
For example, as shown in FIG. 2, it is possible to arbitrarily limit the contact range between the rolls by axially shifting the rolls. Therefore, as described above, the rolling reaction force obtained by tightening the kiss roll-the reduction setting. From the relationship of the values, the average value of the change in radius over the entire effective roll length of the work roll ▲ ▼
Besides, the average value ▲ ▼ 'of the radius change of the part corresponding to the contact range limited by the roll shift is obtained, and the information for obtaining the work roll profile change is increased,
The estimation accuracy of the work roll profile will be improved.

〔Example〕

 Next, a preferred embodiment of the present invention will be described.

First, in the case of a rolling mill without a roll shift function, as shown in FIG. 1, the obtained data includes two data, that is, the kiss roll tightening data immediately after changing the work rolls and the current kiss roll tightening data. Only a diagram. By the way, an oil film bearing is often used as a reinforcing roll bearing of a plate rolling mill. In this case, the oil film thickness in the bearing changes depending on the rotation speed of the roll, and the rolling reaction force obtained by tightening the kiss roll is − The relationship between the rolling reduction values is affected by the roll rotation speed. Since this is an error factor for the method of the present invention that attempts to estimate the fluctuation of the work roll profile, when performing kiss roll tightening, be sure to set a certain fixed rotational angular velocity of the roll before tightening. Or if data is collected at a rotation angular velocity different from that immediately after roll reshuffling, the effect of oil film thickness change due to the difference in rotation angular velocity is estimated separately, and after removing this, the data Comparison and analysis must be done.

Now, as shown in FIG. 1, if the data immediately after recombining and the data after rolling are tightened up to the rolling reaction force region where they are almost parallel, the entire effective cylinder length of the radius change of the work roll is calculated by the formula (1). Average value ▲ ▼ is required. Next, the distribution of the roll radius change ΔR over the effective roll length is estimated. In both cases where the thermal expansion of the roll is large ▲ ▼> 0 and the wear of the roll is large ▲ ▼ <0, the greatest change in radius occurs when the rolling material is constantly in contact. It is considered that the radius change of the roll is very small in the vicinity of the center of the existing roll body and near the end of the roll body where there is little possibility of contact with the rolled material. Therefore, when ▲ ▼> 0, the roll profile changes to a medium convex shape, and when ▲ ▼ <0,
It is presumed that the roll profile changes to a concave shape. Therefore, when the pattern of roll profile change is known to some extent from the operation results, the roll profile change is estimated from ▲ ▼ as follows.

Now, with the center of the work roll as the origin, the coordinate in the roll axial direction is x, and the effective length of the work roll is l. Also,
Assuming that the change pattern of the work roll profile is represented by a known function f (x) of x, the distribution ΔR of the change amount of the work roll radius is ΔR = ΔR (x) = af (x) (2) ) Is expressed. Where a is an unknown parameter, From the above condition, it is calculated by the following equation.

By substituting a in equation (3) into equation (2), the amount of change in the work roll profile can be obtained.

Here, f representing the pattern of work roll profile change
As for (x), a method of obtaining it by substituting the rolling operation conditions up to that point in the roll wear calculation formula and the roll thermal expansion calculation formula may be considered.

Other embodiments include, for example, “KNShohet and NATowns
end: Journal of Iron and Steel Institute, 206-11 (1
968), 1088. "and a method for obtaining the work roll profile by performing a numerical analysis by the split model method. Fig. 3 shows the algorithm of this method. More average radius change ▲
▼ is calculated, and then a roll profile variation ΔR (x) that satisfies ▲ ▼ is assumed. Next, based on the assumed ΔR (x), roll deformation analysis is performed by, for example, the division model method, and the rolling reaction force due to roll deformation −
Find the relationship between the rolling reduction values. It is compared with the relationship of rolling reaction force-reduction set value, which is obtained by performing the same calculation based on the roll profile immediately after the roll change.
ΔR (x) until the difference between the measured values in the figure matches
Then, the convergence calculation is performed again. At this time, ΔR (x)
Since the contact range between rolls particularly in the low load region changes depending on the distribution of, the difference between the measured value and the calculated value in this region is an important index for the convergence calculation.

Here, the method of assuming the distribution of ΔR (x) is a method of combining several roll profile patterns obtained from past operation experience, or a calculation using a roll wear calculation formula and a roll thermal expansion calculation formula. A method of correcting the result may be considered.

Next, an example of a plate rolling machine having a roll axial shift function will be described. First, even in this case,
The change amount ▲ ▼ of the work roll radius averaged over the effective body length 1 of the work roll can be obtained from the kiss roll tightening data in the state where the roll shift is not performed.
For example, as shown in FIG. 2, kiss roll tightening is performed with intermediate rolls or reinforcing roll shifts performed, and the diagram of rolling stress-rolldown set value is the kiss roll tightening performed immediately after roll change in the same state. Compared with the data, it is assumed that a difference in the set rolling value of Δg ′ is observed for the same rolling reaction force in the parallel portion. In the state shown in FIG. 2, there are two types of contact ranges between the rolls in which the work rolls 4 are involved: 1 between the upper and lower work rolls and 1 ′ between the work roll 4 and the intermediate roll or the reinforcing roll 5. Therefore, when the value obtained by averaging the changes in the radius of the work roll over the range of l'is represented by ▲ ▼ ', 2 ▲ ▼ + 2 ▲ ▼' = Δg '(4) is established as an equation corresponding to the equation (1). . Since ▲ ▼ and Δg 'are already known,
From equation (4) Therefore, ▲ ▼ ′ is required. Even in the case of the embodiment in which the pattern of the work roll profile change is assumed in advance, ▲ ▼ 'thus obtained is effective to correct this and improve the accuracy. Also, the third
Even when the work roll profile is calculated by convergence calculation as shown in the figure, the assumed roll profile is
By ▼ ', it becomes possible to further limit the distance, and more rapid convergence can be expected.

If the number of roll shift positions can be increased, the roll profile change can be directly and discretely obtained as follows. In FIG. 2, when the average value of the change amount of the work roll radius in the range of l ″ is ▲ ▼ ″, from the definition of the average value, ▲ ▼ · l = ▲ ▼ ′ · l ′ + ▲ ▼ ″ · l ″ ...... (7) is established, so that ▲ ▼ ″ is obtained by the following equation.

Therefore, by collecting the kiss roll tightening data in which the roll shift amount is changed little by little, ▲ ▼ ″ can be obtained for various ranges from the roll body end, and these values can be expressed by the same relational expression as the expression (7). by substituting for the amount of change in roll radius, it will be asked discretely as the representative value for each shift amount increments of interval (mean value). for example, the cylinder end of l _1, as shown in FIG. 4 range roll radius mean value ▲ ▼ ₁ change in _the average value of the roll radius variation in the range of l ₁ + l ₂ is the ▲ ▼ ₁₂ from the body end, in the region of .l ₂ to that determined by the procedure When the average roll radius change is set to ▲ ▼ ₂ , ▲ ▼ ₁₂・ (l ₁ + l ₂ ) ＝ ▲ ▼ ₁・ l ₁ + ▲ ▼ ₂ + l ₂ holds as in formula (7). ▼ ₂ is calculated by the following equation.

By repeating such a procedure, the average value of the roll radius change in each section is discretely obtained. When it is desired to obtain the roll profile change at an arbitrary position, the average value of the obtained roll radius changes in each section is regarded as the roll radius change at the midpoint of each section, and this can be interpolated.

Next, an embodiment in the case of a rolling mill capable of shifting work rolls will be described. The work roll shift is generally such that the upper and lower work rolls are shifted in opposite directions as shown in FIG. In this case, by the work shift amount ls,
The work roll-reinforcing roll contact range l _B is given by l _B = l-ls, where l is the effective roll length, and the upper and lower work roll contact range lw is given by lw = l-2 ls. Kiss roll tightening was performed in the state as shown in Fig. 5, and the diagram of rolling reaction force-reduction set value was compared with the kiss roll tightening data performed immediately after roll re-arrangement in the same state. In the parallel high load region, it is assumed that a difference in the rolling reduction set value of Δg ′ is observed for the same rolling reaction force. In this case, the average of the value ▲ ▼ w of the work roll changes in the scope of the lw, when the average value ▲ ▼ B of the work roll change in the range of l _B, the following expression is obtained as an expression corresponding to equation (4) .

2 ▲ ▼ w + 2 ▲ ▼ B = Δg '(10) However, in this case, since both ▲ ▼ w and ▲ ▼ B are unknowns, both cannot be obtained as they are. Therefore, some kind of conditional expression was introduced. ▲ ▼ w, ▲
▼ Find B. For example, from the tightening of the kiss roll when the roll shift amount is zero, it is known that the average value of the roll radius change in the contact range 1 is ▲ ▼.
It may be assumed that B is obtained by the interpolation of ▲ ▼ w and ▲ ▼. Assuming that it can be obtained by the simplest linear interpolation, ▲ ▼ B can be obtained as follows.

In this case, l-lw = 2ls, lB-lw = ls, l-lB = ls, and therefore equation (11) is Substituting equation (12) into equation (10) Equation (13) gives the average value of the radius change of the work roll in the range of lw. The usefulness of ▲ ▼ w is the same as that of ▲ ▼ 'of the embodiment in the case of the reinforcing roll or the intermediate roll shift described above, and thus the description thereof is omitted.

Even in the case of the work roll shift type rolling mill, if the upper and lower work rolls can be separately shifted, as shown in FIG. 6, by tightening the kiss roll while only one roll is shifted, the formula ( The formula corresponding to 10) is 3 ▲ ▼ w + ▲ ▼ = Δg '(14), and ▲ ▼ is known, so ▲ ▼ w
Is required.

〔The invention's effect〕

As described above, according to the present invention, it is possible to detect the work roll profile during the rolling operation without using a special measuring device, and improve the accuracy of the plate thickness and plate crown / shape of the rolled plate. A great effect can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a relationship between a rolling reaction force obtained by bringing the upper and lower work rolls of a plate rolling machine into contact with each other and further tightening, and FIG. 2 is a reinforcement roll or an intermediate roll. FIG. 3 is a diagram showing the roll arrangement when a roll shift is performed, FIG. 3 is an example of an algorithm for estimating the roll profile from changes in the rolling reaction force-reduction set value diagram of FIG. 1 before and after rolling, and FIG. FIG. 5 is a diagram showing the division of the rolls, FIG. 5 is a diagram showing a roll arrangement in which the work rolls are shifted by a work roll shift rolling mill, and FIG. 6 is a roll arrangement in which only the upper work rolls are shifted. FIG. 1 ... Rolling reaction force immediately after roll change-reduction set value diagram 2 ... Rolling reaction force-reduction setting value diagram when work roll diameter is large on average 3 ... Work roll diameter is small on average Rolling reaction force-rolling down set value diagram when 4 is ... Work roll 5 ... Reinforcing roll or intermediate roll

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area G01B 21/20 Z

Claims (2)

[Claims] 1. In a plate rolling mill, during a period of interruption of rolling work, a rolling down device is operated to bring the upper and lower work rolls into contact with each other,
Further, by comparing and analyzing the relationship between the set rolling reduction value obtained by further tightening and the measured value of the rolling reaction force by the rolling reaction force measuring device, by comparing and analyzing the relationship when the working roll was installed, the work roll profile from the time of installation A roll profile detection method for a sheet rolling mill, which is characterized by calculating and calculating a change amount of 2. A plate rolling machine having a function of axially shifting a roll is performed by taking two or more positions of the roll capable of shifting and operating a reduction device to tighten the roll during the interruption of the rolling operation. A roll profile detection method for a plate rolling machine according to claim 1.