JP2015193010A - Method for determining irregular roll gap in guide roll group in successive cast machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determining method capable of determining true irregular roll gaps in a guide roll group in which positional offset of a roll gap measurement device and irregular roll gaps measured when a dummy bar travels over a scale or similar cases are excluded.SOLUTION: There is provided a method for determining irregular roll gaps in which: upon determination of presence or absence of irregular in roll gaps, a roll gap measurement device 5a is previously arranged on a dummy bar 5 moving together with pulling out movement of a cast piece to measure roll gaps between each roll in a guide roll group 2 with the roll gap measurement device 5a when the dummy bar 5 passes through the guide roll group 2; an absolute value of deviation between the measured roll gap and a preset roll gap of each roll in the guide roll group is calculated to be compared with a preset criterion value; in a case where it is determined in the step that the absolute value is larger than the preset criterion value, roll gap measurement waveform obtained upon measurement of the roll gap is compared with a normal roll gap measurement waveform in order to determine the presence of irregular in roll gaps.

Description

  The present invention relates to a roll interval abnormality determination method for a group of guide rolls arranged on the exit side (secondary cooling zone) of a casting mold of a continuous casting machine.

  The group of guide rolls arranged on the exit side of the casting mold of the continuous casting machine is supported and guided by a pair of rolls that sandwich the cast slab that is being pulled out on both sides (up and down). In order to achieve stable continuous casting while avoiding bulging and internal cracks that lead to deterioration, the roll interval is strictly controlled.

  Usually, the roll interval of the guide roll group is a measuring instrument attached to a dummy bar (which guides the initial casting portion of a cast slab cast with a casting mold to a pinch roll provided downstream of the continuous casting machine). As a prior art regarding this point, the peak value of the roll interval of each roll obtained with a roll interval meter and a preset roll are used. The method disclosed in Patent Document 1 for determining whether or not there is an abnormality in the roll interval by comparing the interval, the measured value of the interval between the guide roll pairs, and the average value of the interval between the front and rear guide roll pairs are compared. A method disclosed in Patent Document 2 that determines that the roll interval is abnormal when the deviation exceeds a threshold value is known.

JP 2012-245531 A JP-A-8-300122

  By the way, in the above conventional method, the following problems remain, and it has been difficult to determine whether the roll interval is really abnormal.

  In other words, while the cast slab is being pulled out, the measuring instrument is displaced due to the meandering of the dummy bar, passes over the scale accumulated between the rolls, or runs on the roll chock, etc. Even if it is not possible to measure normally, it is difficult to determine whether there is an abnormality in the roll interval because the measured value is recognized as the roll interval. The current situation is that the distance between the rolls is measured in the equipment.

  The subject of this invention exists in the place which proposes the roll interval abnormality determination method of the guide roll roll group in the continuous casting machine which can determine based on the high precision whether there is abnormality in the roll interval of a guide roll group. .

  The present invention relates to a guide roll group installed on the outlet side of a casting mold of a continuous casting machine and sandwiching and guiding cast slabs drawn from the casting mold on both sides thereof, and the roll interval of the guide roll group is set. In determining whether or not there is an abnormality, a roll interval measuring meter is installed in advance in a dummy bar that moves following the drawing movement of the cast slab, and when the dummy bar passes through the guide roll group, a guide roll is provided by the roll interval measuring meter. The roll interval of each roll of the group is measured, the absolute value of the deviation between the measured roll interval and the roll interval of each roll of the preset guide roll group is obtained, and this absolute value and a preset reference When it is determined that the absolute value is larger than a preset reference value in the first step of comparing the values with the first step, the roll interval is further measured. A roll of guide rolls in a continuous casting machine comprising a second stage in which a roll interval measurement waveform obtained at the time of comparison and a roll interval measurement waveform in a normal state is compared to determine that there is an abnormality in the roll interval This is a roll interval abnormality determination method.

  In the present invention, when the correlation coefficient between the roll interval measurement waveform obtained when measuring the roll interval and the roll interval measurement waveform at normal time is obtained, and the correlation coefficient exceeds 0.7, It is preferable to determine that the roll interval is abnormal.

  Here, the roll interval measurement waveform refers to a waveform obtained by assigning a value measured by the roll interval meter to a position tracking value of the roll interval meter. Further, the reference value is obtained by a deviation between a peak value and a preset roll interval of the roll at the narrowest portion of the roll interval measured by a roll interval meter installed on a dummy bar or the like described later. Value.

  According to the roll interval abnormality determination method of the present invention having the above-described configuration, the absolute value of the deviation between the measured roll interval and a preset roll interval is obtained (first stage), and the absolute value of this deviation is obtained. When the absolute value is larger than a preset reference value in comparison with the reference value, the roll interval measurement waveform obtained when measuring the roll interval as the second stage, and the roll interval measurement at normal time Since the correlation coefficient with the waveform is obtained and it is determined that the correlation coefficient is 0.7, it is determined that there is an abnormality. Therefore, the roll interval abnormality due to other factors, i.e., the position deviation of the roll interval meter and the scale of the dummy bar It is possible to eliminate an abnormality in the roll interval caused by the upper passage or the ride on the roll chock, and the frequency of entering the facility can be reduced.

It is the figure which showed typically the continuous casting machine suitable for implementing this invention. It is the figure which expanded and showed the principal part of the dummy bar typically. It is the figure which showed the waveform image in case a roll space | interval is measured normally. It is the figure which showed the waveform image obtained when measuring things other than a roll space | interval at the time of measurement of a roll space | interval. It is the figure which showed the waveform image when a roll space | interval measuring meter remove | deviates from a roll.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 1 is a diagram schematically showing a continuous casting machine suitable for carrying out the present invention.

  1 in FIG. 1 is a casting mold for continuous casting. Further, 2 is a guide roll group arranged in the secondary cooling zone on the outlet side of the continuous casting mold 1 and constituted by a plurality of support rolls (roll pairs), and 3 is a tank for holding a molten metal used for continuous casting. The dish 4 is a sliding nozzle disposed on the bottom wall of the tundish 3, 5 is an immersion nozzle that supplies the molten metal in the tundish 3 to the continuous casting mold 1 through the sliding nozzle 4, and 6 is a continuous casting mold. 1 is a dummy bar that guides the initial casting portion of the cast slab S cast in 1 to a pinch roll r provided at a downstream position of the continuous casting machine.

As shown in FIG. 2, the dummy bar 6 is provided with a roll interval measuring meter 6 a that measures the roll interval g when passing through each roll constituting the guide roll group 2 as shown in FIG. 2. . As the roll interval meter 6a, for example, an encoder 6a ₁ may be used, and a roll interval meter 6a ₁ having a claw portion 6a ₂ that can measure the roll interval g by bringing the back surface into contact with the outer surface of the roll. In the roll interval g measured by the roll interval meter 6a, the narrowest portion is displayed as a peak value.

  Prior to the start of continuous casting, the dummy bar 6 is placed on a carriage 7 installed on the casting floor. When the continuous casting starts, the dummy bar 6 is conveyed to the continuous casting mold 1 and is transferred to the continuous casting mold 1 by means such as a conveyor. It is inserted in.

  When the continuous casting is started, the dummy bar 6 moves in the guide roll group 2, and the roll interval g is measured by the roll interval meter 6a during the movement.

  The roll interval g of each roll constituting the guide roll group 2 can be grasped from the roll interval value measured by the roll interval meter 6a and the tracking position of the roll interval meter 6a at that time.

  When the roll interval g is measured normally when the roll interval g is measured, the value of the roll interval g takes the minimum value (peak value).

  For this reason, as a first step, the roll interval meter 6a measures the peak value of the roll interval g of each roll as the actual roll interval value, and the absolute value of the deviation between the actual roll interval value and the preset roll interval is determined. A value is obtained and monitored whether the absolute value of this deviation exceeds the reference value.

  Then, the absolute value of the deviation exceeds the reference value, that is, the reference value of the roll that is determined to be appropriately determined from the situation of bulging or internal cracking that leads to quality deterioration of the cast slab S, and the roll interval g may be abnormal. Is determined as a second step, the correlation coefficient between the roll interval measurement waveform and the normal roll interval measurement waveform is obtained, and when the obtained correlation coefficient exceeds 0.7, the roll interval g Is determined to be abnormal. The reference value in the first stage can be set to about 5 mm, for example, but this reference value can be appropriately changed depending on the operating conditions, the size of the support rolls constituting the guide roll group 2, and the like. Therefore, the present invention is not limited to the case of setting to about 5 mm.

  The reason why it is effective to determine whether or not the roll interval g is abnormal based on the correlation coefficient is as follows.

  In other words, when two data groups are related, the two data groups are correlated, and the presence or absence of correlation can be determined by making the two data groups scatter plots. This is because, in order to make an objective determination, it is preferable to determine by obtaining a correlation coefficient between two data groups.

  The correlation coefficient takes a numerical value between -1 and +1, and when it is -1, +1, it is a complete correlation (-1 (inverse correlation), +1 (positive correlation)). There will be sex. When the correlation coefficient is 0, there is no correlation and it is determined that the two data groups are not related.

とすると、
相関係数ρは、

で求められることになる。 The correlation coefficient is, for example, that two variables are x and y, and the average is

Then,
The correlation coefficient ρ is

Will be required.

  In the present invention, it is determined that the roll interval g is abnormal when the reference value is abnormal and the correlation coefficient exceeds 0.7. This is because if it exceeds 7, the roll interval g becomes abnormal, and problems such as bulging and internal cracking that lead to quality deterioration of the cast slab S occur.

  Through the above procedure, it is possible to determine whether or not the roll interval g is really abnormal, and the frequency of entering the casting facility (secondary cooling zone) can be reduced as much as possible.

  The tracking position of the roll interval meter 6a is calculated by calculating the distance traveled from the initial position by the dummy bar 6 from the number of rotations of each roll constituting the guide roll group 2, but this tracking position is actually Some deviation may occur.

  Therefore, in obtaining the correlation coefficient, the actual roll interval measurement waveform is gradually shifted in the tracking direction of the measuring instrument 6a with respect to the normal roll interval measurement waveform as a reference, and the roll interval g is the largest. It is desirable to adopt a narrowing value (peak value) as the roll interval g.

  FIG. 3 is a diagram showing a waveform image when the roll interval g is normally measured, FIG. 4 is a diagram showing a waveform image when measuring things other than the roll, and FIG. It is the figure which showed the waveform image when the roll space | interval meter 6a has remove | deviated from the roll in the middle of the measurement of the roll space | interval g.

  When the roll interval g is a normally measured waveform (roll interval measurement waveform) as shown in FIG. 3, the correlation coefficient is close to 1, but the waveforms as shown in FIGS. In this case, the correlation coefficient is less than 0.7, and even if it is determined that there is an abnormality in the roll interval g in the first stage, the value is not due to an abnormality in the roll interval g itself, It can be determined that it is caused by positional deviation, passage on the scale, or riding on a roll chock.

  According to the present invention, when measuring the roll interval g, the measured roll interval g can be used as an index for determining whether or not the abnormality of the measured roll interval g is caused by other factors. If it is not due to abnormalities but due to other factors, it is not necessary to actually enter the continuous casting machine and actually measure it. Can be shortened and the safety of work can be improved. In this case, efficient continuous casting is also possible.

The continuous casting of steel slabs with a continuous casting machine having a by the guide roller group configured by diameter to place a roll pair 158 present in 320~345mm performed multiple times, in this case, provided the dummy bar In addition, the roll interval of the guide roll group was measured with the measured roll interval meter, and the method according to the present invention was applied to determine whether there was any abnormality in the roll interval. The determination result is shown in Table 1 together with the result of actually entering the continuous casting machine and actually measuring the roll interval. The reference value was 5 mm.

  As is clear from Table 1, it was confirmed that the determination method according to the present invention was in good agreement with the actual measurement results and could be determined with high accuracy.

  According to the present invention, it is possible to determine whether or not there is an abnormality in the roll interval of the roll itself by eliminating the roll interval abnormality caused by the positional deviation of the dummy bar, the climbing on the scale, etc. A method can be provided.

DESCRIPTION OF SYMBOLS 1 Casting mold 2 Guide roll group 3 Tundish 4 Immersion nozzle 5 Sliding nozzle 6 Dummy bar 6a Roll interval measuring meter 7 Cart r Pinch roll S Cast slab g Roll interval

Claims (2)

For the guide roll group that is installed on the exit side of the casting mold of the continuous casting machine and that guides and supports the cast slab that is pulled out from the casting mold and supports both sides, whether there is an abnormality in the roll interval of the guide roll group. In judging,
A roll interval meter is installed in advance on a dummy bar that moves in unison with the casting movement of the cast slab, and when the dummy bar passes through the guide roll group, the roll interval of each roll of the guide roll group is determined by the roll interval meter. A first step of measuring, obtaining an absolute value of a deviation between the measured roll interval and a roll interval of each roll of a preset guide roll group, and comparing the absolute value with a preset reference value When the absolute value is determined to be larger than a preset reference value in this first stage, a roll interval measurement waveform obtained when measuring the roll interval, A roll interval abnormality determining method for a guide roll group in a continuous casting machine, comprising a second stage in which it is determined that there is an abnormality in a roll interval by comparing with an interval measurement waveform.   A correlation coefficient between a roll interval measurement waveform obtained when measuring the roll interval and a roll interval measurement waveform in a normal state is obtained, and when the correlation coefficient exceeds 0.7, there is an abnormality in the roll interval. It determines with existing, The roll space | gap abnormality determination method of the guide roll group in the continuous casting machine described in Claim 1 characterized by the above-mentioned.

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