JPH01317611A - Tension control method in continuous rolling mill - Google Patents

Abstract

PURPOSE:To control inter-stand tension to target tension with high accuracy by controlling the inter-stand tension by tension which has been derived from a deflection of a prescribed stand by taking the influence of a rolling load into consideration and deriving the inter-stand tension of a material to be rolled with high accuracy. CONSTITUTION:When a material to be rolled 12 is being rolled by a continuous rolling mill, a deflection of a prescribed stand H4 before and after the stand concerned H4 bites the material to be rolled 12 is detected 16, based on a high fixed position of the stand concerned H4 as a reference. Also, a rolling load of the stand H4 is detected 14, and from these detected deflection and detected rolling load, inter-stand tension of the upstream side or the downstream side of the stand H4 is operated and derived by a computing element 30. Subsequently, the tension is controlled by controlling the speed of revolution of a roller of the continuous rolling mill concerned so that the derived inter-stand tension becomes target tension. As a result, rolling is stabilized, the dimension accuracy of the material to be rolled 12 becomes satisfactory, and also, the yield can be improved.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to a tension control method in a continuous rolling mill, and in particular, a method for controlling tension in a continuous rolling mill, in which the tension acting between stands is determined by calculation, and the tension determined during rolling is set as a target tension. This invention relates to a tension control method. [Prior art J] In general, in a continuous rolling mill, unless the O-roll rotational speeds of each stand are mutually balanced so that the mass flow (volume velocity) of the material to be rolled is constant, the Tension begins to move in the rolled material. This tension acting on the rolled material may deteriorate the dimensional accuracy of the product and lead to a decrease in yield, and in order to prevent the dimensional accuracy from deteriorating, the operator must control the continuous rolling mill.
This is complicated because it causes intervention. Therefore, in order to ensure product dimensional accuracy and stable operation, in continuous rolling mills, the tension (
It is necessary to perform rolling while controlling the tension (between stands) to the target tension. For this reason, various tension control techniques have been invented or implemented in the past.
There are two main types: tension estimation method (indirect method) and tension direct detection method. That is, the tension estimation method is a method in which a torque arm is determined from rolling torque and rolling load, and tension is estimated based on this torque arm. However, with this method, the tension calculation error increases as you move toward the downstream stand.
Further, there is a drawback that the torque arm cannot be completely corrected for changes in material dimensions on the input side and the output side due to skid marks or when using reduction control, etc., resulting in a large error in tension calculation. Further, the tension direct detection method detects the synergistic deviation amount of each stand between two stands and between multiple stands with a deviation detector such as a differential transformer provided between the stands,
This method compares the measured displacement amount with a reference tension signal, assuming that it is similar to the actual tension, and controls the roll rotation speed so that the inter-stand tension becomes the target tension based on the comparison result. . This method includes, for example,
There is one disclosed in Japanese Patent No. 11928. This method calculates and controls the tension without increasing the calculation error of the tension as in the tension estimation method, and in this respect, it is possible to perform tension control with high precision. however,
In this method, the deviation of the stand is considered to be caused only by the tension, and in actual rolling where rolling loads are applied, the deviation of the stand due to the rolling load is large, so the error in the detected tension is large ( [Problem to be solved by the invention 1] Therefore, in the conventional tension control technology, when detecting the tension between the stands from the deviation of the stands, it is assumed that the deviation changes only depending on the tension. Therefore, the tension between the stands is not determined by considering the rolling load, but the tension is determined with high accuracy.
Furthermore, there was a problem in that the tension could not be controlled with high precision. Furthermore, since a detector for detecting the deviation of the stands is provided between the stands, there are problems in terms of maintenance and inspection. [Object of the Invention] The present invention has been made to solve the above-mentioned conventional problems, and is to accurately determine the inter-stand tension of a material to be rolled and to control the inter-stand tension to a target tension with high precision. It is an object of the present invention to provide a tension control method in a continuous rolling mill that allows for the detection of deviation of a predetermined stand and that does not cause maintenance or inspection problems with a detector for deviation of a predetermined stand. [Means for Solving the Problems] The present invention provides a method for rolling a material to be rolled using a continuous rolling mill.
Detecting the deviation of the predetermined stand of the continuous rolling mill after the predetermined stand has bit the material to be rolled relative to before the predetermined stand has bit the material to be rolled, with reference to a predetermined position outside the predetermined stand, and detecting the rolling load of the predetermined stand. , from the detected deviation and the detected rolling load, calculate the inter-stand tension on the upstream side or downstream side of the predetermined stand, and adjust the roll rotation speed of the continuous rolling mill so that the obtained inter-stand tension becomes the target tension. The above objective is achieved through control.

[Effect]

The present invention will be explained in detail below. Specified stand of continuous rolling mill (hereinafter referred to as tube i stand)
The deviation of the i-th stand detected with reference to a predetermined position outside, for example, the pedestal of the continuous rolling mill, varies depending not only on the tension of the material to be rolled but also on the rolling load. Therefore, the rolling load F l s (
1-1) Let Ti be the tension that acts on the rolled material between the i-th stands, and when the rolling load Fi and tension T+ are applied to the i-th stand, the i-th stand with respect to the above predetermined position. Assuming that the deviation after the biting of the rolled material with respect to before biting is ΔQ1, various studies were conducted on the relationship between the deviation ΔQ i s rolling load F1 and the tension Ti, and the results were as follows. That is, if the deviation ΔQi when the rolling load Fi acts independently on the i-th stand is ΔQ + F, and the deviation ΔQ1 when the tension Ti acts independently on the i-th stand is ΔQIT, then the following equation can be expressed between them: (1) and (2) hold true. ΔQi F−f i (Fi) ・・
・(1)ΔQiv−g! (Ti)・
...(2) Also, since the rolling load F+ and the tension Ti each independently act on the deviation ΔQi, when the rolling load FI and the tension T1 act simultaneously on the i-th stand, the following equation (3) holds true. . ΔQ1−ΔQ+p+ΔQiy −r i (Fi)+! It i (Ti)...(3
) Therefore, the tension Ti can be obtained by detecting the deviation ΔQ1 and the rolling load Fi of the i-th stand, and calculating and solving the equation (3) with respect to the tension Ti. Then, by controlling the roll rotation speed of the continuous rolling mill so that the required tension Ti becomes the target tension Traim, the actual inter-stand tension can be controlled to the target tension T1aim. The present invention has been made based on the above knowledge, and since the inter-stand tension is determined from the stand deviation, the influence of the rolling load on the deviation is taken into consideration, so the inter-stand tension can be determined with high accuracy. This improves tension control accuracy. Therefore, rolling is stabilized, dimensional accuracy is improved, and the economical effect of improved yield can be enjoyed. Further, the deviation is detected based on a predetermined position outside the predetermined stand, and a detector for detecting the deviation is placed outside the predetermined stand. i
Since the detector can be placed in the same place, maintenance and inspection of the detector can be facilitated. Note that the tension Tt is the tension between the (i-1)th stand and the first stand, that is, the tension on the upstream side of the first stand, but the tension determined and controlled by the present invention is not limited to this, and Also for the tension on the downstream side of one stand (1) ~
The tension can be similarly determined and controlled using equation (3). Here, the specific relationship between the tension between the stands and the rolling load with respect to the deviation ΔQi in the first stand of a continuous rolling mill as shown in FIG. 1, for example, will be explained. While the rolled material 12 is being rolled by the rolling roll 10 in the i-th stand, the load detector 14 detects the rolling load Fi, and the stand deviation detector 16 detects the conveyance direction of the rolled material 12 (arrow in the figure). When the deviation ΔQi in six directions) is detected, the relationship of the deviation ΔQiF to the detected rolling load FC is as shown in FIG. 2, and the inter-stand tension T
The relationship of the deviation ΔQiy with respect to + is as shown in FIG. In this case, the unit of the deviation ΔQ i p s ΔQiy detected by the stand deviation detector 16 is ton. As shown in FIGS. 2 and 3, rolling load F i
s Since the deformation of the first stand due to the tension T1 is normally elastic, the deviation ΔQip with respect to the rolling load Fi,
It can be seen that the relationship between ΔQir and tension T1 is linear. Therefore, if the relationship shown in the figure is determined in advance through experiments or actual measurements, and the equations (1) and (2) above are determined from that relationship, each deviation ΔQ due to the rolling load Fi and the tension Tf can be calculated. By calculating equations (1) to (3) using t F % Q i t and rolling load FI, the tension T
I can be found. It should be noted that, as shown in Fig. 2, the deviation ΔQIF is greatly influenced by the rolling load Fi.
-11928, etc.), it can be inferred that if the tension between the stands of the material to be rolled changes depending only on the deviation of the stands and the tension is determined only based on the deviation, the accuracy of the obtained tension will be poor. In contrast, in the present invention, the tension is calculated by taking into account the rolling load, so
It can be seen that the tension can be determined and controlled with high precision.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. This example shows the final stand and its first stand that have the most influence on product dimensions in a V-H type continuous rolling mill in which vertical roll stands and horizontal roll stands are provided alternately.
The tension between the stands in front of the stage is controlled by the present invention. This continuous rolling mill has four stands, and FIG. 1 shows the configuration of the final stand of this continuous rolling type and the third stand one stage before the final stand. The final stand, that is, the fourth stand corresponds to the first stand, and the fourth stand is equipped with a horizontal rolling roll 10 that rolls the material to be rolled 12 from above and below. Also, the third stand one stage before that is the previous stand (i-
This third stand is equipped with a vertical roll 19 for rolling the material to be rolled 12 from the width direction and a vertical roll frame 21 for supporting the vertical roll 19. Note that the first stand (not shown) has a vertical roll, and the second stand has a horizontal roll. The frame 18 of the rolling roll 10 includes a load detector 14 for detecting the rolling load, and a fourth stand whose other end is attached to a pedestal 20 that does not cause positional fluctuations.
A stand deviation detector 16 for detecting i is provided. Note that this fourth stand has rolling roll 1.
A final stand main motor 22 is provided for driving 0. Further, the third stand is equipped with a third stand main motor 24 for driving the vertical roll 19. Furthermore, each roll of the first and second stands (not shown) is provided with a main motor for driving each roll. A load detection circuit 26 is connected to the load detector 14 . Further, a stand deviation detection circuit 28 is connected to the stand deviation detector 16. Each of these detection circuits 26.28 is for converting the detection value detected by each detector 14.16 into an electric signal (detection value signal). Each of the detection circuits 26 and 28 is connected to an arithmetic unit 30, and inputs the converted detection value signal to the arithmetic unit 30. The calculator 30 first calculates the above-mentioned equations (1) to (3) based on the input detection signal, calculates the tension T4 between the third stand and the fourth stand, and then calculates the tension T4 between the third stand and the fourth stand. Tension T4 and target tension T4 a
This is to find the speed correction amount ΔN of each stand main engine motor that can make the difference ΔT1 from im to zero. The determined speed correction amount ΔN is input to the main engine speed control 11 device 32. The main machine speed control device 32 is for controlling the speed of each stand main machine motor, and corrects the speed of each stand main machine motor using the input speed correction ΔN, and detects the roll speed of each stand. This is to precisely control the tension T4 so that it becomes the target tension T4 aill. In addition, in the case of the embodiment, the stand on which the speed of the main engine motor is corrected by the main engine speed control device 32 is the first stand.
Stand ~ 3rd stand. In addition, the reference numeral 34 in the figure is
This is an upstream tension controller, and in order to avoid affecting the tension between the upstream stands when the roll rotation speed of the downstream stand is controlled, the roll rotation speed of the upstream stand is also changed by the same ratio valve. The effects of the embodiment will be explained below. In this embodiment, when rolling the material 12 to be rolled in the continuous rolling manner shown in FIG. 1, the rolling load F1 of the fourth stand is detected by the load detector 14, and the material The stand deviation detector 16 detects the deviation ΔQi in the six directions indicated by arrows in the figure. The detected rolling load Fi and deviation ΔQi are converted into detection value signals by the load detection circuit 26 and stand deviation detection circuit 28, and are input to the calculator 30. The arithmetic unit 30 stores in advance the above-mentioned equations (1) and (2) determined from experiments or actual measurements, for example, based on the relationships shown in FIGS. 1)
, (2), and the detected rolling load F1 and deviation ΔQi input as electric signals, calculate the above-mentioned equations (1) to (3), and calculate the tension between the third stand and the fourth stand. T4
is calculated by calculation. Next, this calculator 30 calculates the obtained tension T4 and the target tension T between the third stand and the fourth stand.
4 a! The main engine motor of each stand (in the case of the example, the first stand ~
The speed correction amount ΔN of the main engine motor of the third stand is determined and input to the main engine speed control I table device 2. The main engine speed control device 32 corrects the speed of the main engine motor of each stand based on the input speed correction amount ΔN, sets the roll speed of each stand to an appropriate value, and accurately adjusts the actual tension T4 between the stands to the target tension T4aim. Good control. Next, we will discuss a second example in which only the tension T4 between the third stand and the final stand was determined by the method of the present invention in a V-H continuous rolling mill of the same type as the continuous rolling mill according to the above example. This will be explained based on FIG. Obtained tension T
4 was as shown in Figure (C). Also, < in the same figure
The tension T2 between the first and second stands is shown in A), and the tension T2 between the first and second stands is shown in (B) of the figure.
) shows the tension T3 between the second and third stands. In this case, the tensions T2 and T3 are calculated by determining a torque arm from the rolling torque and rolling load of each rolling roll, and calculating based on the determined torque arm. Also, target tension between each stand (unit tension)
is O, Okg/n2, but in this second embodiment, speed control for the tension subsurface is not performed for each main engine motor as shown in FIGS. (D) to (F). In addition,
(G) in the figure shows the change in the oval dimension of the rolled material (the cross-sectional dimension of the rolled material 10) when determining the tension T4. From the figures (C) and (G), it can be seen that the oval dimension changes depending on the variation of the tension T4 between the third stand and the fourth stand, and it can be seen that the tension is accurately determined according to the present invention. Next, under the same conditions as in the second embodiment, the third stand~
A third embodiment will be described with reference to FIG. 5, in which the tension T4 between the fourth stands is calculated and the speeds of the main motors of the first to third stands are controlled based on the calculated tension T4. Note that FIGS. 4A to 4G show the same calculation and detection results as FIGS. 4A to 4G. As shown in the figure, the tension between each stand T2, T3, T
4 is within ±0.1/u2 of the target tension after the material to be rolled is caught in each stand and fluctuates, and as shown in (G) in the figure, the oval tension is within ±0.1/u2 of the target tension. The dimensions are also not affected by changes in tension. From this,
It can be seen that the method of the present invention allows the tension to be controlled with high accuracy, and thereby allows the rolled material to be accurately processed to target dimensions. In the above embodiment, the predetermined stand was the fourth stand, and the tension between the stands determined and controlled by calculation was the tension between the third stand and the fourth stand, that is, the tension on the upstream side of the predetermined stand. Any stand in the machine may be used, and the inter-stand tension to be determined and controlled can be determined and controlled not only on the upstream side but also on the downstream side, as long as the predetermined stand is not the R end stand. Further, in the above embodiment, in order to control the inter-stand tension M, the roll rotation speed was controlled in the first to third stands on the upstream side, excluding the fourth stand (predetermined stand), but the present invention The rolls whose speeds are controlled when controlling the inter-stand tension are not limited to the rolls of the first to third stands. That is, for example, the inter-stand tension can be controlled by controlling the roll rotation speed of the stands including the predetermined stand, or the inter-stand tension can be controlled by controlling only the roll rotation speed of the predetermined stand. can. Furthermore, in the above embodiments, the present invention was carried out using a four-stand V-H type continuous rolling mill, but the continuous rolling mill in which the present invention is carried out is a continuous rolling mill having such a number and type of stands. However, the present invention can be practiced with continuous rolling mills of other numbers or types of stands. [Effect of the invention 1] As explained above, according to the present invention, the inter-stand tension is determined from the deviation of a predetermined stand in consideration of the influence of the rolling load, and the inter-stand tension is controlled by the determined tension. Tension accuracy is high, and tension control viscosity is highly reliable. Therefore, it is possible to obtain economical effects such as stable rolling, good dimensional accuracy of the rolled material, and improved yield. Furthermore, since the deviation of the predetermined stand is detected with reference to a predetermined position outside the stand, excellent effects such as ease of maintenance and inspection of the deviation detector can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a layout diagram of main parts including a partial block diagram showing the main parts of a continuous rolling mill and the configuration of a tension control system according to an embodiment of the present invention, and Fig. 2 is a detailed explanation of the present invention. FIG. 3 is a diagram showing an example of the relationship between stand deflection and rolling load; FIG. 3 is a diagram showing an example of the relationship between stand deflection and tension; FIG. A diagram showing an example of the calculation and detection results of the tension between each stand, the main machine speed correction amount of each stand, and the oval dimension in a continuous rolling mill. Figure 5 also shows other values of the tension between each stand, the speed correction amount, and the oval dimension. It is a miniature map showing an example of calculation and detection results. DESCRIPTION OF SYMBOLS 10... Roll roll, 12... Rolled material, 14... Load detector, 16... Stand deviation detector, 18... Frame, 19... Vertical roll, 20... Frame, 22... R end stand main rock motor, 24... Third stand main engine motor, 26... Load detection circuit, 28... Stand deviation detection circuit, 30... Arithmetic unit, 32. ...Main engine speed control device.

Claims (1)

[Claims] (1) When rolling a material to be rolled in a continuous rolling mill, the deviation of the predetermined stand of the continuous rolling mill after biting the material to be rolled relative to before it bites the material to be rolled is measured outside the predetermined stand. detecting a predetermined position of the predetermined stand as a reference, detecting the rolling load of the predetermined stand, calculating the inter-stand tension on the upstream side or downstream side of the predetermined stand from the detected deviation and the detected rolling load, and calculating the inter-stand tension on the upstream side or downstream side of the predetermined stand, A method for controlling tension in a continuous rolling mill, comprising controlling the number of rotations of rolls in the continuous rolling mill so that the tension reaches a target tension.