JPS6356308A - Device for preventing drawing-in of rolling mill - Google Patents

Abstract

PURPOSE:To discover abnormality in an early stage and to take prompt emergency remedy by taking at lest one of the speed change or tension change of a strip and the load change or rolling load change of rolling rolls as a signal and comparing the same with a standard signal during rolling. CONSTITUTION:The peripheral speed of the rolling rolls by a pulse oscillator 13, the rolling roll load from the load current of a rolling motor 5, the rolling load from the differential pressure of a rolling down cylinder 8 and the tension on the strip from the downward pressure of a deflecting roll 11 are respectively taken in as signals and the signals are outputted respectively via a calculator. The signals are compared with a stationary level signal and a circuit 41 for preventing drawing in is triggered in the case of abnormality. The discovery of the abnormality and the remedy thereof are easily made by the device constituted in the above-mentioned manner.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a squeezing prevention device for a rolling mill, and more particularly to an improvement of a squeezing preventing device for a rolling mill suitable for preventing strip squeezing accidents during rolling of thin steel sheets in a cold rolling mill.

[Conventional technology]

When a strip is continuously rolled in a rolling mill, a so-called squeezing accident may occur at one end of the strip due to various factors such as deformation of the strip being rolled, such as wavy patterns at both ends, misalignment of the center, and strong rolling of the rolling rolls. There is. FIG. 2 shows a case where the strip 1 is normally rolled by the rolling mill 2, and FIG. 3 shows a case where narrowing occurs in the portion indicated by the arrow P. If rolling continues in a state where such a squeezing accident has occurred, not only will the quality of the product be impaired, but in severe cases it may lead to accidents such as roll breakage or strip breakage. Conventionally, there is a technique disclosed in Japanese Patent Publication No. 51-41985, for example, as a technique for preventing such strip narrowing troubles. This technology detects the thrust force generated in the rolls of the multi-high rolling mill when the strip is rolled by the multi-high rolling mill, and stops the multi-high rolling mill based on this detection. This is an attempt to minimize damage to the roll by releasing the roll.

[Problems to be solved by the invention]

However, strip squeezing is caused by a combination of multiple factors, and therefore, thrust force is not always generated when squeezing occurs. Therefore, in the above-mentioned prior art, there is a problem that in some cases, even though squeezing actually occurs, it cannot be accurately detected, which may lead to roll breakage or the like.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and provides a squeezing prevention device for a rolling mill that can detect strip squeezing early and accurately and minimize damage caused by the strip squeezing. The purpose is to provide

[Means to solve the problem]

The present invention provides at least one signal among a change in the speed of the strip, a change in the load on the roll, a change in the rolling load of the roll, and a change in the tension of the strip when the strip is rolled by the rolls of a rolling mill. a means for comparing the taken-in signal with each standard signal during stable rolling; and a means for comparing the taken-in signal with each standard signal during stable rolling; The above object is achieved by providing means for executing at least one of the narrowing Wj stop operations for increasing the tension of the return machine.

[Effect]

As a result of repeated various experiments, the present inventor has found that when narrowing down occurs, a predetermined qualitative tendency is detected for the four elements described below. The present invention
This was done based on this knowledge. (1) Stripping speed: Figure 4 shows the stripping speed on the unwinding side, the circumferential speed of the rolling roll,
and no relationship between backward rate. The reversing rate is determined by the formula: (peripheral speed of the roll - strip speed on the unwinding side)/peripheral speed of the roll. As is clear from the figure, during steady rolling, the circumferential speed of the rolling roll and the strip speed on the unwinding side are extremely stable. Therefore, the backward movement rate is also low and stable. However, when squeezing occurs, rolling is not performed normally, and
The relationship between the circumferential speed of the rolling roll and the strip speed on the unwinding side is extremely disrupted. That is, even though the circumferential speed of the rolling roll is constant, the strip speed on the unwinding side is extremely undulating and decreasing, and as a result, there is a tendency that the backward movement rate is also undulating and increasing. Therefore, by detecting this tendency, it is possible to know the occurrence of narrowing down. Furthermore, even when the strip is running diagonally,
This can be detected as a sudden change in the reverse speed. = 4 - (2) Roll load: Figure 5 shows the fluctuation state of the load on the roll (roll load current). As is clear from the figure, during steady rolling, there is little load variation on the rolling rolls. However, when squeezing occurs, for example, if the ends of the strip are bent due to poor strip shape, or if the ends of the strip become wavy and overlap at the bottom of the rolling rolls, There is a tendency for the rolling roll load to increase extremely. Therefore, the occurrence of squeezing can be known by detecting the load state of the rolling rolls. (3) Rolling load of rolling rolls: Fig. 6 shows the fluctuation state of rolling load (rolling pressure) of rolling rolls. As is clear from the figure, during steady rolling, the rolling load level is low and there are few fluctuations. However, when squeezing occurs, the rolling load reaches a high level and fluctuations also increase. Therefore, by detecting the fluctuation state of the rolling load of the rolling rolls, it is possible to know the occurrence of squeezing. (4) Rewinding side strip tension I to lip tension Fig. 7 shows the fluctuation state of the strip tension on the unwinding side. As is clear from the figure, during steady rolling, the strip tension is at a high level and there is little variation. Also, there is little difference when comparing the center part of the strip and the end part. However, in an abnormal situation, a large change may occur in the tension distribution in the width direction of the strip, or a tension change may occur due to winding misalignment of the unwinding machine or equipment failure, which may cause narrowing. In other words, this indicates that the occurrence of squeezing can sometimes be known by detecting the strip tension on the unwinding side during rolling. In the present invention, attention is paid to the qualitative trends of the above four elements when narrowing down occurs, and it is possible to know that narrowing down has occurred by detecting fluctuations or abnormalities in these elements with respect to the standard state. . As a countermeasure for this, an operation to prevent squeezing is performed by a combination of one or more of the following: reducing the rolling speed, rapidly opening the rolling rolls, and increasing the tension of the unwinding machine. As a result, narrowing down can be detected early and accurately, and furthermore, it is possible to automatically take measures to prevent the narrowing down from expanding any further. Note that, in the present invention, it is not necessarily necessary to detect all of the above four elements when detecting narrowing down. Therefore, for example, if you try to respond to narrowing down as early as possible, narrowing down will not occur when an abnormality is detected in one (or two, or three) of the above four elements. On the other hand, if you try to respond only when narrowing down clearly occurs, you can respond as if narrowing down has occurred for the first time when all four elements are detected as abnormal. You can also.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 1 does not schematically show a strip rolling facility in which an embodiment of the squeezing prevention device for a rolling mill according to the present invention is adopted. The strip 1 is unwound from its coiled form in an unwinder 3;
It is continuously rolled in the direction of arrow A in the figure. During rolling, the strip 1 is under tension by an unwinder 3 and an unwinder motor 6 in a direction opposite to the direction in which the strip travels. Further, the rolling roll 4 is connected to a rolling device 7 and a rolling cylinder 8.
A rolling blade is added in the direction of arrow B in the figure. The rolling mill motor 5 controls the rolling speed, and the unwinding machine 3 controls the strip tension at appropriate levels, respectively, by a rolling mill/winding machine control device 20. Next, a detector for detecting the state during rolling in the above apparatus and its signal relationship will be explained. (1) Stripping speed on the unwinding side of the rolling mill: The stripping speed on the unwinding side of the rolling mill is converted to the rotational speed of the detection roll 21, and is detected by the pulse oscillator 22 as the stripping speed signal 35 on the unwinding side. (1') Circumferential speed of the rolling roll: ' -8- The circumferential speed of the rolling roll 4 is detected as the rolling rolling peripheral speed signal 32 by the directly connected pulse oscillator 13. (2) Roll load: The load on the roll 4 during rolling is determined by the load current of the rolling mill motor 5, and is detected as a roll load signal 39. (3) Rolling load of the rolling roll: The rolling load of the rolling roll 4 is determined by the differential pressure of the rolling cylinder 8, and is detected by the pressure detector 31 as a rolling pressure signal 40. (4) The unwinding side force of the tensioned crab strip 1 takes the downward pressure of the deflector roll 11 between the rolling mill 2 and the unwinding machine 3,
The tension detector 29 generates a strip tension signal 33 on the unwinding side.
Detected as . Next, the main circuit configuration of the above device will be explained. This circuit is
It can be broadly divided into four systems. (1) Slip speed abnormality detection: Rewinding side Slip speed signal 35 and rolling roll circumferential speed signal 32 are output as a backward rate signal 42 by a backward rate calculator 41. The first steady level setter 43 is for setting a standard backward rate at a steady state during rolling, and outputs a backward rate steady level signal 44. The first comparator 45 compares the backward rate signal 42 during rolling with the steady level signal 44 of the backward rate, and outputs a backward rate abnormal signal 46 if the backward rate during rolling becomes greater than a predetermined value. The reverse rate abnormality signal 46 triggers the narrowing down prevention circuit 47. The squeezing prevention circuit 47 is connected to the rolling mill/unwinding machine electric control device 20, and has the functions of reducing the speed of the rolling mill, rapidly opening the rolling rolls, and increasing the tension of the unwinding machine in appropriate combinations. have. (2) Roll load abnormality detection: The second steady level setter 51 sets the standard roll load current during steady rolling, and the load steady level signal 5
Outputs 2. The steady load level signal 52 is compared with the rolling roll load signal 39 by a second comparator 53, and if the rolling roll load signal 39 becomes greater than the steady load level signal 52 by a predetermined value or more, a rolling roll load abnormality signal 54 is output. Ru. The rolling roll load abnormality signal 54 is input to the squeezing prevention operation circuit 47, and the same operation function as described above is activated. (3) Rolling load abnormality detection: The third steady level setter 61 sets the standard rolling load (standard rolling pressure) during steady rolling, and outputs a steady pressure level signal 62. The steady pressure level signal 62 is compared with the rolling pressure signal 4o by a third comparator 63, and if the rolling pressure signal 4o becomes greater than the steady pressure level signal 62 by a predetermined value or more, an abnormal pressure signal 64 is output. The pressure abnormality signal 64 is input to the narrowing prevention operation circuit 47, and the same operation function as described above is activated. (4) Strip tension abnormality detection on the unwinding side: The fourth steady level setter 71 sets the standard tension during steady rolling, and outputs a tension steady level signal 72. The steady tension level signal 72 is compared with the strip tension signal 33 on the unwinding side by a fourth comparator 73, and when the strip tension signal 33 on the unwinding side becomes larger than the steady tension level signal 72 by a predetermined value or more, a tension abnormality signal 74 is generated. is output. The tension abnormality signal 74 is input to the narrowing prevention operation circuit 47, and the same operation function as described above is activated. In this rolling equipment, the squeezing prevention operation circuit 47 is triggered when any one of the reverse rate abnormality signal 46, the rolling roll load abnormality signal 54, the pressure abnormality signal 64, and the tension abnormality signal 74 is generated. It has become. As mentioned above, the squeezing prevention operation circuit 47 can: (1) rapidly reduce the rolling mill speed; (2) rapidly open the rolling rolls;
■It has the function of increasing the tension of the unwinding machine. Further, the narrowing-down operation circuit 47 appropriately selects the above-mentioned combinations of (1) to (2) and each operation amount according to the type and quantitative value of the abnormal signal taken in. The output of this squeezing prevention operation circuit 47 is transmitted to the above-mentioned known rolling mill/unwinding machine electric control device 20, and the rolling mill 2 and the unwinding machine 3 are respectively controlled to prevent squeezing. Next, a second embodiment of the present invention will be described based on FIG. 8. In this second embodiment, the present invention is applied to a reverse-type general-purpose Sendzimir mill. Since it is a reverse type, it is possible to detect the reduction on both the entry and exit sides of the rolling mill. (1) Strip speed change,
(2) Changes in the load current of the rolling roll motor, (3) Changes in the rolling load of the rolling roll, and (4) Changes in the tension of the strip are the same as in the previous example. A detailed explanation will be omitted by simply adding a sign or a minus sign. This second embodiment has functional enhancements in the following points. (5) Detection of strip tension abnormality on the winding side: Similar to the above-described abnormality detection of the strip tension on the unwinding side, a sudden change in the strip tension on the winding side is also a factor in narrowing down the selection. As for the circuit configuration, the winding side strip tension signal 34 is also input to the fourth comparator 73 by the winding side force detecting device 30 attached to the lower part of the winding side deflector roll. As a function, when the winding side strip tension signal 34 becomes lower than the standard tension steady level signal 72, which is properly set in advance, by a predetermined value or more, the tension abnormality signal 74 is outputted. The tension abnormality signal 74 triggers the narrowing prevention operation circuit 47,
Thereafter, the rolling mill, the unwinding machine 3, and the winding machine 9 are controlled in the same manner as described above. (6) Abnormal speed detection at both ends of the strip width: Squeezing occurs on either or both of the drive side and the non-drive side of the strip width. Therefore, in this second embodiment, strip speed detection rolls (21.23 mm on the unwinding side) are installed near both ends of the strip width to compare the abnormalities in the backward movement rates of both rolls. As for the circuit configuration, both the rewind side strip speed signals 35 and 36 from the pulse oscillators 22 and 24 on the drive side and the anti-drive side are inputted to the backward rate calculator 41. As for this action, both reverse speed ratio signals 42 are compared with reverse speed steady level signal 44, and if either of them reaches an abnormal level, a reverse speed abnormal signal 46 is output. Thereafter, the rolling mill 2 and the unwinding machine 3 are controlled in the same manner as described above. According to this second embodiment, it is possible to accurately detect narrowing in both the predetermined direction and reverse rolling in reverse rolling, and to deal with this.

【Effect of the invention】

As explained above, according to the present invention, strip squeezing accidents in rolling mills can be prevented, and damages such as deterioration of strip quality and roll damage caused by squeezing accidents can be minimized. . As a result, it becomes possible to improve the productivity of the rolling mill and the yield of rolled material.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view including a partial block diagram of a rolling equipment equipped with a squeezing prevention device in which the first embodiment of the present invention is adopted, FIG. 2 is a perspective view showing a normal rolling state, and FIG. teeth,
FIG. 4 is a perspective view showing a state in which squeezing has occurred; FIG. Fig. 6 is a diagram showing the variation of the rolling load, Fig. 7 is a diagram showing the variation of the strip tension on the unwinding side, and Fig. 8 is a diagram showing the variation of the strip tension on the unwinding side. 1 is a schematic perspective view including a partial block diagram of a Sendzimir mill with a prevention device; FIG. 1... Strip, 2... Rolling machine, 3.
... Rewinding machine, 4... Roll, 5.
...Rolling mill motor, 6...Rewinding machine motor,
7... Rolling down device, 10... Winding machine motor, 13... Pulse oscillator for rolling mill, 20... Rolling machine/unwinding machine electric control device, 21... Unwinding/anti-drive side Detection roll, 22... Rewind/anti-drive pulse oscillator, 23... Rewind/drive side detection roll, 24... Rewind/drive pulse oscillator, 31... Pressure detector, 32... Rolling port, -ru peripheral speed signal, 33... Unwinding side strip tension signal, 35... Unwinding side strip speed signal, 39... Rolling roll load signal, 40... Rolling pressure signal, 43. ...first steady level setter, 44...reverse rate steady level signal, 45...first comparator, 46...reverse rate abnormal signal, 47...limiting prevention circuit, 51...th 2 Steady level setter, 52... Load steady level signal, 53... Second comparator, 54... Load abnormality signal, 61... Third steady level setter, 62... Pressure steady level. Signal, 63... Third comparator, 64... Pressure abnormality signal, 71... Fourth steady level setter, 72... Tension steady level signal, 73... Fourth comparator, 74. ...Tension abnormality signal.

Claims (1)

[Claims] (1) When rolling a strip by a rolling roll of a rolling mill, at least one signal among a change in speed of the strip, a change in load on the rolling roll, a change in rolling load on the rolling roll, and a change in tension in the strip; a means for comparing the taken-in signal with each standard signal during stable rolling; and a means for reducing the rolling speed, rapidly opening the rolling rolls, when the result of the comparison is abnormal; A squeezing prevention device for a rolling mill, comprising: means for performing at least one of the squeezing prevention operations of increasing the tension of an unwinding machine.