JP2003290827A - Method for detecting abnormal rolling in multi roll mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect abnormal rolling in a multi roll mill instantaneously during rolling. <P>SOLUTION: By detecting the current value of rolling load at each stand of the multi roll mill, whether it is abnormal rolling or not is judged by the variation of the detected current value of the rolling load. The judgement is performed by whether or not the current value of the rolling load at a certain stand of the multi roll mill is decreased not less than a predetermined threshold value as compared with the current value of the rolling load at the normal time and the current value of the rolling load at the next stand is increased not less than the predetermined threshold vale as compared with the current value of the rolling load at the normal time. Then, by detecting the abnormal rolling in the multi roll mill in an early stage during rolling and preventing the continuation of the abnormal rolling, nonconforming materials in quality having roll marks, slip marks or the like are reduced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting rolling anomalies in a multi-stage rolling mill, and more particularly to a method for detecting a rolling anomaly suitable for a multi-stage rolling mill such as a mandrel mill, sizer or reducer in a seamless pipe production line. It is a thing.

[0002]

2. Description of the Related Art In a multi-high rolling mill, one of the stands
Even if an abnormality occurs in the book roll, rolling can be performed unless there is any abnormality in the other rolls of the same stand and the stands before and after the stand in which the abnormality has occurred, so that the rolled material does not stop midway. Therefore, for example, the rolling may be continued until the surface inspection in the lower step is performed, and a material having a nonconforming material is largely generated.

In order to prevent the generation of such quality incompatible material, for example, Japanese Patent Application Laid-Open No. 8-300021 discloses a method for detecting the timing of biting of the tube end of the raw tube into the stretch reducer and slip-out. Has been done. Further, Japanese Utility Model Laid-Open No. 3-9203 discloses an apparatus for detecting the quality of the rolling state of a mandrel mill. In addition, JP-A-7-
Japanese Patent No. 194186 discloses an apparatus for detecting an abnormality of a motor and its drive target by a rolling load current value (hereinafter, simply referred to as "load current value").

[0004]

However, the detection method disclosed in Japanese Patent Application Laid-Open No. 8-300021 detects the torsion torque in the drive shaft of each stand of the stretch reducer, and based on the power spectrum level of the frequency component thereof. Although it is recognized as biting in or slipping out, rolling can be performed even when one roll of one stand is broken during rolling by a multi-stage rolling mill. It is not possible to judge roll breakage.

Further, the detecting device disclosed in Japanese Utility Model Laid-Open No. 9203/1993 determines the quality of the rolling condition by comparing a predetermined result with the result of the current rolling, so that the rolling condition of one roll is determined. Although it is possible to judge the quality of the roll, it is not possible to detect the breakage of the roll because the materials before and after the current rolling are not compared.

Further, the detecting device disclosed in Japanese Patent Laid-Open No. 7-194186 detects two or more motors having the same driving condition and detects an abnormality by the difference in the load current value between the motors. So each stand is driven by one motor, like a stretch reducer,
When the motor driving conditions are different between the respective stands, the abnormality cannot be detected by the difference in the load current value of the motor. Further, in such a multi-stage rolling mill, the load current value of the motor fluctuates depending on the tension balance from the upstream side or the downstream side, so that it becomes difficult to detect rolling abnormality.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to prevent abnormal rolling in a multi-high rolling mill from occurring.
An object of the present invention is to provide a rolling anomaly detection method for a multi-high rolling mill, which can be instantly detected during rolling.

[0008]

In order to achieve the above-mentioned object, a rolling abnormality detecting method for a multi-high rolling mill according to the present invention detects a load current value at each stand of the multi-high rolling mill and detects the detected load. Whether the rolling is abnormal or not is determined based on the change in the current value.

By doing so, it becomes possible to instantly detect, during rolling, a rolling abnormality that causes a quality problem that cannot be detected by a measuring instrument such as a wall thickness gauge or an outer diameter gauge. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A large quantity of non-conforming material is considered to have a dimensional problem that can be detected by a measuring instrument (fat thickness gauge, outer diameter gauge, etc.) provided on the delivery side of the rolling mill. However, there are some quality problems such as roll streak that cannot be detected by the measuring device, but in the case of roll fracture, there is a quality problem that cannot be detected by the measuring device such as the roll streak. , The detection must be done during rolling.

As a result of various investigations by the inventor of the present invention, it has been found that when the rolling abnormality occurs, the load current value changes, for example, the load current value at the abnormal rolling stand and the stands before and after the abnormal rolling change from the normal state. .

[0012] For example, regarding roll breakage among abnormal rolling, it is assumed that one of the rolls of one stand will break, but at this time, one roll is rolled at the broken stand. Since there is not, the load current value will decrease. On the contrary, the load current value is increased by the amount that the load on the broken stand is reduced by the one stand on the subsequent stage.

The rolling anomaly detection method for a multi-high rolling mill according to the present invention was made based on this finding. The load current value at each stand of the multi-high rolling mill is detected, and the change in the detected load current value is detected. By this, it is judged whether or not there is a rolling abnormality.

More specifically, in the rolling abnormality detecting method for a multi-high rolling mill according to the present invention, whether or not there is a rolling abnormality due to a change in load current value is determined for each rolling in each stand of the multi-high rolling mill. The load current value is detected for each stand, the load current value of the material currently being rolled is compared with the previous load current value for each stand, and it is determined whether the difference between the two has exceeded a preset threshold value. Or, the load current value at a stand of a multi-stage rolling mill decreases by a predetermined threshold value or more compared to the load current value at the normal time, and the load current value at the next stand is set at a predetermined value compared to the load current value at the normal time. It is carried out depending on whether or not it has increased by a threshold value or more, or whether or not there is a sudden change (judgment based on a change in inclination) when the load current value during rolling is continuously monitored in each stand of the multi-high rolling mill.

According to the rolling anomaly detection method for a multi-stage rolling mill according to the present invention described above, a rolling anomaly such as a rolling anomaly caused by a roll breakage cannot be detected by a measuring instrument such as a wall thickness gauge or an outer diameter gauge. It becomes possible to instantly detect a rolling abnormality of a seamless pipe in which a problem occurs, particularly during rolling.

In the rolling anomaly detection method for a multi-high rolling mill according to the present invention, when a rolling anomaly is detected, extraction of the next and subsequent materials is stopped and a roll replacement instruction is issued. It becomes possible to effectively suppress the generation of incompatible materials.

In the rolling anomaly detection method for a multi-high rolling mill according to the present invention described above, the load current used to determine whether or not an anomaly occurs is an average value excluding a peak value. As the threshold value, a value appropriately determined from the outer diameter and the wall thickness based on past generation data is used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rolling abnormality detecting method for a multi-high rolling mill according to the present invention will be described below with reference to FIGS. Figure 1
Is a flow chart of a rolling abnormality detecting method of a multi-stage rolling mill according to the present invention corresponding to claim 2, FIG. 2 is a flow chart of a rolling abnormality detecting method of a multi-stage rolling mill according to the present invention corresponding to claim 3, and FIG. The figure which showed an example of the result of having measured the load current value during rolling in each stand of a rolling mill, FIG.
Shows an explanatory view of a rolling abnormality detecting method for a multi-stage rolling mill according to the present invention, which corresponds to claim 4.

A rolling abnormality detecting method for a multi-high rolling mill according to the present invention detects a load current value at each stand of a multi-high rolling mill such as a stretch reducer, and determines whether there is a rolling abnormality due to a change in the detected load current value. As the load current value to be detected, the load current value of the material being rolled and the load current value of the previous rolling are used for each stand, or the rolling current at one stand and the next stand is used. You can use the load current value during medium and normal rolling,
The load current value during rolling at each stand is used.

When using the load current value of the material being rolled and the load current value of the previous rolling for each stand, for example, the load current values are compared in the order shown in the flow chart of FIG. Then, it is determined whether the rolling is abnormal.

That is, first, the load current value during rolling is detected for each rolling at each stand, and the average value excluding the peak value is calculated. Next, for each stand, the load current value (average value) of the material being rolled is compared with the load current value (average value) of the previous rolling. Then, if the difference between the two exceeds the threshold value determined in advance from the outer diameter and the wall thickness based on the generated data in the past, it is determined that the rolling is defective, while the difference between the two is less than the threshold value. It is judged to be good.

When using the load current values during rolling and normal rolling in one stand and the next stand, the load current values are compared in the order shown in the flow chart of FIG. It is determined whether the roll is abnormal.

That is, first, the load current value of the material being rolled on a certain stand is detected, and the average value excluding the peak value is calculated. Then, the load current value (average value) is compared with the load current value (average value) during normal rolling, and the decrease amount of the load current value (average value) exceeds the preset threshold value as described above. In this case, the load current value of the material being rolled at the next stand is detected, and the average value excluding the peak value is calculated. On the other hand, when the amount of increase or decrease of the load current value (average value) of the material being rolled is less than the preset threshold value, it is determined to be good.

Next, the load current value (average value) of the material being rolled at the next stand is compared with the load current value (average value) during normal rolling, and the increase amount of the load current value (average value) is determined. If it exceeds the preset threshold value as described above, it is determined that the roll is abnormal, while the increase or decrease amount of the load current value (average value) of the material being rolled is less than the preset threshold value. Is judged to be good.

When the load current value during rolling in each stand is used, the load current value during rolling is continuously monitored in each stand, as shown in FIG. 3, for example. Then, as shown in FIG. 4, the load current value during rolling in each stand where these monitoring is continued,
When a sudden change (change in inclination) has occurred, it is determined that a rolling abnormality has occurred at this sudden change. In addition,
FIG. 4B is a diagram in which the load current value shown in FIG. 4A is differentiated so that the determination of rolling abnormality can be easily performed.

In the rolling anomaly detection method for a multi-stage rolling mill according to the present invention described above, when a rolling anomaly is detected, extraction of the next material and subsequent materials is stopped and a roll replacement instruction is issued. It becomes possible to effectively suppress the generation of incompatible materials.

Next, description will be made on the basis of the result of an experiment conducted for confirming the effect of the rolling abnormality detecting method for a multi-high rolling mill according to the present invention. In the experiment, the material is JIS G 4051.
S25C specified in s has an outer diameter of 82.6 mm and a wall thickness of 2
This was carried out by carrying out the method of the present invention corresponding to claim 3 shown in FIG. 2 when a 5.4 mm blank tube was subjected to squeeze rolling using a 6-stand stretch reducer.

FIG. 5 (a) is a view showing the load current value of the material at the time of normal rolling detected in advance at the sixth stand, and FIG. 5 (b) is the load of the material currently being rolled at the sixth stand. It is the figure which showed the electric current value.

Further, FIG. 5 (c) is a diagram showing the load current value of the material at the time of normal rolling detected in advance at the seventh stand, and FIG. 5 (d) is the material currently being rolled at the seventh stand. It is the figure which showed the load current value of.

Comparing these average values excluding the peak value of the load current value in the sixth stand shown in FIGS. 5 (a) and 5 (b), in the current rolling in the sixth stand, compared with the normal rolling, It can be seen that the average value is decreasing.

On the other hand, comparing the average values of the load current values in the seventh stand shown in FIGS. 5 (c) and 5 (d) excluding the peak value, the current rolling in the seventh stand shows that
It can be seen that the average value is increased as compared with the case of normal rolling.

In this experiment, since the decrease amount of the sixth stand and the increase amount of the seventh stand were both larger than the predetermined threshold value as described above, it was judged that the rolling was defective.

[0033]

As described above, according to the present invention,
It is possible to detect abnormal rolling in a multi-stage rolling mill early during rolling, prevent abnormal rolling from continuing, and reduce quality nonconforming materials such as roll flaws and slips.

[Brief description of drawings]

FIG. 1 is a flowchart of a rolling abnormality detecting method for a multi-stage rolling mill according to the present invention, which corresponds to claim 2.

FIG. 2 is a flowchart of a rolling abnormality detecting method for a multi-stage rolling mill according to the present invention, which corresponds to claim 3;

FIG. 3 is a diagram showing an example of a result of measuring a load current value during rolling in each stand of a multi-stage rolling mill, in which (a) to
(F) is the figure which showed the load current value of the 1st-6th stand.

FIG. 4 is an explanatory view of a rolling abnormality detecting method for a multi-stage rolling mill according to the present invention, which corresponds to claim 4;

FIG. 5 is a diagram showing an embodiment of a rolling anomaly detection method for a multi-stage rolling mill according to the present invention, which corresponds to claim 3, (a) and (b) at a sixth stand, and (c) and (d) at It is the figure which showed the load current value of the material in the 7th stand, (a)
(C) is for normal rolling which has been previously detected, (b) and (d)
[Fig. 3] is a diagram showing a current rolling time.

Claims (6)

[Claims] 1. A rolling abnormality of a multi-stage rolling mill, characterized by detecting a rolling load current value at each stand of the multi-roll rolling mill and judging whether or not there is a rolling abnormality based on a change in the detected rolling load current value. Detection method. 2. The method for detecting abnormal rolling of a multi-high rolling mill according to claim 1, wherein whether or not there is abnormal rolling due to a change in rolling load current value is used to determine whether or not rolling is performed at each stand of the multi-high rolling mill.
The rolling load current value is detected each time, and the rolling load current value of the material currently being rolled is compared with the previous rolling load current value for each stand, and the difference between the two exceeds the preset threshold value. A method for detecting rolling anomalies in a multi-high rolling mill, which is characterized in that 3. The rolling abnormality detection method for a multi-stage rolling mill according to claim 1, wherein whether or not there is a rolling abnormality due to a change in rolling load current value is determined when the rolling load current value at a stand with the multi-stage rolling mill is normal. The rolling load current value is decreased by a predetermined threshold value or more, and the rolling load current value at the next stand is increased by a predetermined threshold value or more compared with the normal rolling load current value. A method for detecting rolling anomalies in a multi-high rolling mill. 4. The rolling load current value during rolling in each stand of the multi-stage rolling mill is determined by whether or not there is a rolling abnormality due to a change in rolling load current value in the rolling anomaly detection method for a multi-stage rolling mill according to claim 1. A method for detecting rolling anomalies in a multi-high rolling mill, which is performed depending on whether or not there is a sudden change (judgment based on a change in inclination) when monitoring is continued. 5. The rolling abnormality detecting method for a multi-high rolling mill according to claim 2, wherein when a rolling abnormality is detected, extraction of the next material and subsequent materials is stopped and a roll replacement instruction is issued. Rolling anomaly detection method for multi-high rolling mills. 6. The rolling abnormality detection method for a multi-high rolling mill according to claim 2, wherein the multi-high rolling mill is a rolling mill for seamless pipe rolling. Method.