JPH08132110A - Device for detecting chattering in rolling mill - Google Patents

Abstract

PURPOSE: To detect chattering caused by axial vibration of a work roll in cross roll rolling mill or the like for executing asymmetric rolling as seen in the width direction of a workpiece. CONSTITUTION: Loads which act on right and left roll chocks 4b1 , 4b2 of a back-up roll 3b are detected with load cells 51 , 52 and load signals P1 , P2 are fed to a subtraction circuit 61. The vibrational component ▵PH of difference signal ▵P from the subtraction circuit is outputted with a high-pass filter 62 and a vibrational amplitude signal ▵PH( DC) corresponding to an amplitude level is obtained with an absolute-value circuit 63 and low-pass filter 64. The signal ▵PH( DC) is compared with a threshold ▵PH( DC)th in a deciding section 7 and, when the signal exceeds the threshold, an alarm signal S is outputted. Since the load signals P1 , P2 have periods and amplitudes corresponding to the axial vibration of the work roll 2b and are in opposite phase relation, the vibrational component is emphasized by the difference signal ▵P and, consequently, the chattering caused by the axial vibration is detected with high accuracy.

Description

Detailed Description of the Invention

[0001]

The present invention relates to hot rolling, cold rolling,
The present invention relates to a chattering detection device in a rolling system that performs plastic deformation processing of a material for processing a metal plate by using a plurality of cylindrical rolls for rolling such as thick plate rolling, and particularly detects chattering in the axial direction of a work roll. The present invention relates to a chattering detection device that can perform.

[0002]

2. Description of the Related Art In the technical field of rolling, the vibration of rolling rolls, the vibration of the entire rolling mill, the vibration of the tension of the processed material, etc. are collectively referred to as chattering, and such chattering causes the surface of the material. The striped pattern is called chatamark. Such chatter marks become larger as the amplitude of chattering becomes larger, which may cause the plate thickness variation to exceed the allowable error and may cause a serious defect in the appearance of the product. The detection of chattering amplitude levels is very important for forming quality products. In a conventional chattering detection device, as disclosed in, for example, Japanese Unexamined Patent Publication No. 50-159453, a vibration component of rolling load or rolling speed is detected, and a chattering frequency peculiar to the rolling mill is detected from the detected component. Chattering is detected by extracting the component. Furthermore, it is also known to detect chattering based on the vibration component of the tension of the processed material.

[0003]

In the conventional chattering detection device, as described above, chattering is detected based on the rolling load, the rolling speed, or the tension of the work material. It is a physical quantity that is symmetrical with respect to the direction (left-right direction). Therefore, in the conventional example, it is not possible to detect left-right asymmetric chattering in the width direction of the processed material, such as chattering caused by axial vibration of rolls during left-right asymmetric rolling.

The axial vibration of the roll that causes left-right asymmetric chattering will be briefly described with reference to FIG. FIG. 5 (A) schematically shows a state in which the pair of work rolls 2 _a and 2 _b are arranged so that the axial directions of the work material 1 are aligned with each other in the width direction of the processing material 1, and normal left-right symmetrical rolling is performed. It is a side view. On the other hand, as shown in FIG. 5B, like the cross roll rolling, the work rolls 2 _a and 2 _b are arranged such that the axial directions of the work rolls 2 _a and 2 _b are shifted in the forward and reverse directions, respectively. 5 (C) is a side view schematically showing a state in which the work rolls are rolled, and FIG. 5 (C) shows that the work rolls 2 _a and 2 _b are arranged with their axial directions shifted in the same direction from the width direction of the processing material 1. FIG. 3 is a side view schematically showing a state in which left-right asymmetric rolling is performed.

[0005] FIG. 5 (B) and rolling asymmetrical as shown in (C), as shown in the top view of FIG. 5 (D), the traveling direction of the workpiece 1 to the work roll 2 _a (and 2 _b) A rolling reaction force F _{X in} X (that is, a direction perpendicular to the width direction Y of the processed material 1) is generated, and the rolling reaction force F _X is in the axial direction y of the work roll.
Thrust force F _y that is a component of Since the work roll is displaced in the axial direction _y by such thrust force F _y , the work roll tries to return by the spring force of the work roll supporting mechanism. When the restoring force becomes larger than the frictional force between the surface of the work roll and the surface of the processing material, the work roll slips on the surface of the processing material 1 and returns to its original state. By repeating such a phenomenon, the work roll vibrates in the axial direction y, and chatter marks are generated on the surface of the rolled plate material.

Therefore, in order to prevent the occurrence of chatter marks, it is necessary to detect the chattering due to the vibration of the work roll in the axial direction, which occurs when the work roll axis is displaced from the width direction of the work material to perform asymmetric rolling. However, in the conventional device, such chattering could not be detected. Therefore, an object of the present invention is to provide a chattering detection device capable of detecting chattering due to axial vibration of a work roll.

[0007]

In order to achieve the above object, in the chattering detection device of the present invention, the left and right load signals at the left and right ends of the work roll are
Paying attention to the fact that it has a period and amplitude corresponding to the axial vibration of the work roll, and has an antiphase relationship, and obtains a signal emphasizing the vibration component by taking the difference between them, and only the vibration component in the signal is obtained. By processing the signal to detect the amplitude,
The feature is that chattering due to axial vibration of the work roll can be detected with high sensitivity.
Load detecting means for directly or indirectly detecting loads acting on the left and right ends of the work roll to output left and right load signals, and (b) detecting a difference between the left and right load signals. And (c) a vibration amplitude detecting means for detecting the amplitude of a vibration component of a predetermined frequency or higher in the difference signal and outputting a vibration amplitude signal. It has a feature. The chattering detection device of the present invention further comprises a determination means for comparing the level of the vibration amplitude detection signal with a predetermined reference level and generating an alarm signal when the level exceeds the reference level. When the above condition is reached, an alarm is issued to prevent the chatter mark generated on the processed material from exceeding a predetermined size.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a chattering detection device according to an embodiment of the present invention. In FIG.
_a and _2b are a pair of work rolls arranged vertically, _3a ,
_3b is a backup roll. Also, 4 _a1 , 4 _a2 ,
4 _b1 and 4 _b2 are roll chocks arranged at the left and right ends of the backup rolls 3 _a and 3 _b , 5 ₁ and 5 ₂ are load cells provided in the lower roll chocks 4 _b1 and 4 _b2 , 6 is a signal processing unit, 7 Is a determination unit. The signal processing unit 6 includes a subtraction circuit 61, a high-pass filter 62, an absolute value circuit 63, and a low-pass filter 64, and the absolute value circuit 6
3 and the low pass filter 64 constitute an amplitude detection circuit. The determination unit 7 includes a memory 71 and a comparison circuit 72, determines whether the level of the signal from the low pass filter 64 exceeds a reference level, and generates a determination signal such as an alarm output.

The operation of the chattering detection device of the embodiment shown in FIG. 1 will be described. With the work material 1 being rolled by the work rolls 2 _a and 2 _b , the load cells 5 ₁ and 5 ₂ detect the loads acting on the left and right roll chocks 4 _b1 and 4 _b2 , and the left and right load signals P ₁ , P _{2 to} the subtraction circuit 61 of the signal processing unit 6. The reason why the subtraction circuit 61 is used in the present invention will now be described. The left and right load signals P ₁ and P ₂ are signals that vibrate with axial vibration of the roll, but the left and right roll chock 4 _Since the loads acting on _b1 and _4b2 vibrate in an antiphase relationship, the load signals P ₁ and P ₂ can be expressed as shown in FIGS. 2A and 2B. Therefore, the two load signals P
_{Even if 1} and P ₂ are added, as shown in FIG.
The obtained sum signal P ₁ + P ₂ contains almost no vibration component. In the present invention, the subtraction circuit 61 is used to calculate the difference between the _two load signals P ₁ and P ₂ to obtain the difference shown in FIG.
A difference signal ΔP = P ₁ -P ₂ as shown in (C) is obtained, whereby the vibration component is emphasized.

When the subtraction circuit 61 outputs the difference signal ΔP shown in FIG. 3A, for example, the high-pass filter 62.
Removes the low-frequency component that is steadily included in the difference signal ΔP and outputs the high-frequency component as shown in FIG. 3B, that is, the vibration component ΔP _H. Then, the vibration component ΔP _H is converted into an absolute value signal | ΔP _H | in the absolute value circuit 63 (FIG. 3 (C)) and smoothed by the low pass filter 64, as shown in FIG. 3 (D). , The vibration amplitude signal Δ corresponding to the amplitude level of the vibration component ΔP _{H in} the difference signal ΔP
PH _(DC) is output. The vibration amplitude signal ΔP _{H (DC)} is supplied to the determination unit 7 and, if necessary, to a display unit (not shown) to display the waveform of the signal ΔP _{H (DC) and} the like.

The memory 71 of the judging section 7 stores the rolling conditions U ₁ , U ₂ , U ₃ , ... As shown in FIG.
A look-up table showing the relationship between the chatter mark size V and the value of the vibration amplitude signal ΔP _{H (DC)} , which is obtained empirically in accordance with the above, is stored in advance. Therefore, for example, the rolling condition U _i (i = 1, 2, 3, ...) And the allowable chatter mark size, that is, the chatter mark
When the threshold V _th is input to the memory 71, the value of the vibration amplitude signal ΔP _{H (DC)} corresponding thereto is read from the memory 71 as the amplitude threshold ΔP _{H (DC) th} . The comparator circuit 72 uses the read amplitude threshold ΔP _{H (DC) th} as a reference level, and the low-pass filter 6
It is determined whether or not the signal ΔP _{H (DC)} from 4 exceeds the reference level, and if it exceeds the reference level, the alarm signal S is output.

The comparison circuit may have a hysteresis characteristic. In addition, the determination unit 7 is provided with two or more comparison circuits, and each chatter mark threshold V _{th serving} as a reference level of the comparison circuits can be read out from the memory 71, so that the amplitude of the vibration component can be set to a plurality of levels. You may make it possible to determine. In the above embodiment, the signal processing unit 6 and the determination unit 7 may be configured by digital circuits, or may be realized by software executed by a digital computer. In these cases, it is necessary to sample the load signals P ₁ and P ₂ at regular (or irregular) time intervals to form discrete signals and input them to a digital circuit or a computer via an analog / digital conversion circuit. Furthermore, in the above embodiment, 2
One load cell is provided on the left and right roll chocks of the backup roll, but in a rolling mill that does not have a backup roll, it can be provided on the work roll roll chock. Needless to say, the load cells may be arranged so that the respective loads acting on the ends of the load can be detected.

[0013]

As described above, according to the present invention, the vibration amplitude level is detected by measuring the respective rolling loads applied to the left and right ends of the work roll, and taking the difference between the rolling loads to detect the vibration amplitude level. Chattering due to axial vibration of the roll can be detected with high sensitivity and high reliability. Also, by monitoring the level of chattering detected, an alarm can be issued when the chattering mark caused by chattering exceeds a predetermined size.

[Brief description of drawings]

FIG. 1 is a block diagram showing a chattering detection device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the principle of the present invention.

FIG. 3 is a waveform diagram showing waveforms of a main part of the chattering detection device shown in FIG.

FIG. 4 is a graph for explaining the contents of a lookup table included in a determination circuit included in the chattering detection device shown in FIG.

FIG. 5 is an explanatory diagram for explaining the occurrence of left-right asymmetric vibration as viewed in the width direction of the processing material.

[Explanation of symbols]

1 Processing Material 2 _a , 2 _b Work Roll 3 _a , 3 _b Backup Roll 4 _a1 , 4 _a2 , 4 _b1 , 4 _b2 Roll Chock 5 ₁ , 5 ₂ Load Cell

Claims (2)

[Claims] 1. A chattering detection device for a rolling mill, comprising: (a) load detection means for directly or indirectly detecting loads acting on the left and right ends of a work roll and outputting left and right load signals. And (b) subtraction means for detecting the difference between the left and right load signals and outputting the difference signal, and (c) detecting the amplitude of a vibration component of a predetermined frequency or more in the difference signal to vibrate. A chattering detection device, comprising: a vibration amplitude detection means for outputting an amplitude signal, capable of detecting chattering in the axial direction of a work roll. 2. The chattering detection device according to claim 1, further comprising a determination means for comparing the level of the vibration amplitude detection signal with a predetermined reference level and generating an alarm signal when the level exceeds the reference level. A chattering detection device characterized by being provided.