JPH09113209A - Method and instrument for measuring shape of steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the shape of a steel strip which is run while the strip is rolled under tension without scratching the strip nor receiving any influence from residual magnetization by impressing an alternating magnetic field upon the strip and installing a plurality of sensors at regular intervals in the width direction of the strip. SOLUTION: In order to find the stress of a steel strip 1 which is run between an un-coiler 5 and coiler 7 while the strip 1 is rolled with working rolls 6, a magnetic field impressing device 2 which impresses an alternating magnetic field upon the strip 1 and a plurality of sensors 4 which are arranged in the width direction of the strip 1 and composed of Barkhausen noise detectors 3 are provided. In addition, holding rolls 8 are provided so as to prevent the occurrence of bending stresses caused by the deflection of the strip. Since a noise-stress converting device and an elongation display 9 connected to the sensors 4 are connected to the working rolls 6, data can be fed back to the rolling line. By finding the amount of noise by means of the sensors 4 and the tension distribution or elongation distribution on the strip 1 from the previously found relation between the amount of noise and tension and changing the rolling condition, a prescribed shape is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of latent shape of a steel strip rolling and running under tension.

[0002]

2. Description of the Related Art In the rolling of steel strips, it is required that there is no shape defect such as selvage elongation or medium elongation, that is, the elongation in the rolling direction is uniform in the width direction. On the other hand, when tension within the elastic limit is applied to the steel strip during rolling and the elongation in the rolling direction becomes constant in the width direction, the shape of the steel strip becomes latent and becomes apparently flat. At this time, even if the elongation in the rolling direction is constant, the tension in the width direction is different, and as a result, a tension distribution is generated in the width direction according to the tension difference. By measuring the tension distribution in the width direction, the latent shape of the steel strip rolling under tension can be detected online.

The method of measuring the tension is roughly classified into a method of utilizing the fact that the change when an external force is applied varies depending on the tension and a method of measuring the material property changed by the tension.

Those which apply an external force are classified into a contact type and a non-contact type. In the contact type, there is a hollow multi-division roll method in which a steel strip is elastically bent by a roll having a function of detecting stress and the distribution of tension in the width direction is obtained from the pressure applied to the roll. The non-contact type is a magnetic attraction type in which the steel strip is bent by magnetic force and the distribution of the tension in the width direction is obtained from the displacement of the steel strip in inverse proportion to the tension.

The magnetic permeability method, which measures the magnetic permeability using a magnetic anisotropy sensor, is one of the methods for measuring the material properties changed by the tension. This is based on the measurement principle that the inverse magnetostriction effect, that is, the magnetization process of the magnetic substance changes according to the applied stress, and the in-plane anisotropy of the initial magnetic permeability when the external magnetic field and the magnetization of the steel strip are near zero. It is a method of determining tension by measuring the property.

[0006]

SUMMARY OF THE INVENTION The contact type method for measuring various changes when an external force is applied requires a large space because an apparatus for applying an external force becomes large. Since the roll is a divided roll in the method of applying the external force by the roll, there is a possibility that the steel strip surface may be damaged by the direct contact between the steel strip and the roll. Further, since bending is applied to the steel strip by a roll, the surface layer of the steel strip may be plastically deformed and warped if the yield stress is small or the plate thickness is large.

On the other hand, the method for obtaining the material properties of the steel strip is structurally simple. However, in the method of measuring the initial magnetic permeability, an external magnetic field and the magnetization of the steel strip must be made zero before the measurement, so that a degaussing device must be provided.

The present invention has been made in view of such problems, and an object thereof is to measure the latent shape of a steel strip rolling and running under tension.

[0009]

In order to solve the above problems, the present invention provides a magnetic field for a steel strip having ferromagnetism rolling under tension so that the steel strip is magnetically saturated. A magnetic field is applied alternatingly by an application device, and multiple sensors with Barkhausen noise detectors are installed side by side in the width direction at a certain distance from the steel strip to measure the tension in the width direction and measure the tension of the steel strip. Detect latent shape.

If a mechanism such as a trolley is used, the distance between the steel strip and the magnetic field applying device and the sensor is constant, so not only accurate measurement can be performed but also a non-contact state causes mechanical damage to the steel strip. can avoid.

The application of a magnetic field, the measurement of the Barkhausen noise amount, and the conversion of the noise amount (hereinafter referred to as the Barkhausen noise amount) to the tension are performed electrically, so that the steel strip running immediately is performed. The tension of can be calculated. In addition, since the steel strip is once magnetized, there is no need for demagnetization. The amount of noise is converted to tension by applying a predetermined tension to the same kind of material as the steel strip to be measured, measuring the amount of noise with the above measuring device, and checking the relationship between tension and noise in advance. To do.

[0012]

The principle of tension measurement by measuring the amount of noise according to the present invention will be described below. When tension is applied to a ferromagnetic material to cause elastic strain, the change in magnetization in the direction in which the tension is applied changes due to the inverse magnetostriction effect. Barkhausen noise occurs because the domain wall discontinuously moves in the magnetization process of the ferromagnetic material, and corresponds to the change in magnetization, so the tension can be obtained by measuring the amount of noise.

When tensile stress is applied to the ferromagnetic material, the amount of noise increases, and when compressive stress is applied, the amount of noise decreases. However, the amount of noise differs depending on the magnetization state.
Further, the steel strip usually has a remanent magnetization. Therefore, it is necessary to create a constant magnetization state. Once the steel strip is magnetically saturated in one direction, then a magnetic field is applied to the steel strip until it is magnetically saturated in the opposite direction, and the maximum noise amount during that period is defined as the noise amount of the steel strip. The effect of remanent magnetization can be eliminated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a sensor having a Barkhausen noise detector, which is composed of a magnetic field applying device 2 and a Barkhausen noise detector 3 capable of applying a magnetic field to the steel strip 1 in an alternating manner. Indicates that.

In FIG. 2, a plurality of sensors 4 are arranged in the width direction of the steel strip 1 in order to measure the distribution of tension in the width direction, and the values are displayed on the noise stress transducer and (potential) elongation indicator 9. This is an example of the above. The distance between the sensor and the steel strip depends on the magnitude of the applied magnetic field and the detection sensitivity, but is usually 0.5 mm.
Separated by ~ 3 mm.

FIG. 3 shows an example applied to a steel strip rolling line. A sensor 4 including a magnetic field applying device 2 and a Barkhausen noise detector 3 is provided to obtain the stress of the steel strip 1 running while being rolled by the work roll 6 between the rewinding machine 5 and the winding machine 7. There is. A holding roll 8 is provided in order to prevent bending stress from occurring due to the bending of the steel strip 1. The noise stress converter and the (latent) elongation indicator 9 connected to the sensor 4 are connected to the work roll 6 and can be fed back to the rolling line.

FIG. 4 is a flow chart showing data and their processing when the latent shape is controlled by obtaining the noise amount in rolling. The amount of noise is obtained by a sensor, the tension distribution or (potential) elongation distribution is obtained using the relationship between the noise amount and the tension obtained in advance, and the rolling conditions are changed from this distribution to obtain the prescribed shape. is there. However, the conversion from the noise amount into the tension is convenient, and the noise amount may be directly used to control the rolling mill.

[0019]

EFFECTS OF THE INVENTION According to the present invention, the shape of a steel strip can be measured immediately and without being damaged by the residual magnetization without damaging the steel strip rolling under tension.

[Brief description of the drawings]

FIG. 1 shows a sensor having a Barkhausen noise detector of the present invention.

FIG. 2 is a diagram showing measurement of tension distribution in the width direction of the steel strip of the present invention.

FIG. 3 is a diagram in which the present invention is carried out on a steel strip rolling line.

FIG. 4 is a flowchart showing data and their processing when controlling a shape in the present invention.

[Explanation of symbols]

 1 steel strip 2 magnetic field applying device 3 Barkhausen noise detection device 4 sensor 5 rewinding machine 6 rolling mill working roll 7 winding machine 8 holding roll 9 noise stress converter and (potential) elongation indicator

Claims (2)

[Claims] 1. A Barkhausen noise detector that applies a magnetic field to a steel strip having ferromagnetism rolling and running under tension by a magnetic field so that the steel strip is magnetized and saturated. The shape measurement of the steel strip characterized by measuring the tension distribution in the width direction and detecting the latent shape of the steel strip by installing multiple sensors with a certain distance from the steel strip side by side in the width direction. Method. 2. A steel strip in which a plurality of sensors each having a magnetic field applying device and a Barkhausen noise detector are installed side by side in a width direction at a certain distance from a steel strip having ferromagnetism rolling and running under tension. Shape measuring device.