JP-7855190-B2 - Method for measuring the external dimensions of a metal material and method for calibrating a device for measuring the external dimensions of a metal material.

JP7855190B2JP 7855190 B2JP7855190 B2JP 7855190B2JP-7855190-B2

Inventors

吉田隆司
関根司
笹原いつか
竹村透
黒木寛

Assignees

日本製鉄株式会社
株式会社シーピーアイテクノロジーズ

Dates

Publication Date: 20260508
Application Date: 20220216

Claims (17)

A method for measuring the external dimensions of a metal material to be measured using a two-dimensional imaging device installed above the metal material to be measured, Multiple two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of one of the imaging ranges of the two-dimensional imaging devices. Calibration step: A calibration jig having multiple point light sources arranged at predetermined intervals from each other is positioned such that a portion of the point light sources are located at the periphery of the imaging range of the two-dimensional imaging device; the multiple two-dimensional imaging devices image the point light sources of the calibration jig; the difference between the distance between two points of the point light sources in the imaging data of the point light sources and the distance between two points of the point light sources in the calibration jig is determined as an error; it is determined whether the error is less than or equal to a preset threshold; and if the error exceeds the threshold, the orientation of the two-dimensional imaging device is adjusted. The imaging step involves imaging the metal material to be measured using the plurality of two-dimensional imaging devices to obtain imaging data of the metal material, A method for measuring the external dimensions of a metal material, comprising: a measurement step of determining the distance between the long sides or short sides of a metal material from the position of the long side or short side of the metal material in imaging data of the metal material.
The method for measuring the external dimensions of a metal material according to claim 1, wherein the frequency of the calibration step is less than the frequency of the imaging step and the measurement step.
The method for measuring the external dimensions of a metal material according to claim 1 or 2, characterized in that the multiple two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward.
The method for measuring the external dimensions of a metal material according to any one of claims 1 to 3, characterized in that a verification step is performed to verify the dimensional measurements obtained by the plurality of two-dimensional imaging devices before the imaging step.
The method for measuring the external dimensions of a metal material according to any one of claims 1 to 4, wherein the central region of the imaging range is a region in which the amount of distortion in the image when the metal material to be measured is imaged is 3% or less.
The method for measuring the external dimensions of a metal material according to any one of claims 1 to 5, wherein the central region of the imaging range is an area of 50% or more of the total area of the imaging range.
The method for measuring the external dimensions of a metal material according to any one of claims 1 to 6, wherein the two-dimensional imaging device is an infrared camera.
A method for measuring the external dimensions of a metal material according to any one of claims 1 to 7, wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device and imaging is performed.
Multiple two-dimensional imaging devices are installed above the metal material to be measured, The system includes an image processing means that determines the external dimensions of a metal material to be measured based on the imaging data output from the two-dimensional imaging device, A calibration method for measuring the external dimensions of a metal material, wherein the plurality of two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of any of the imaging ranges of the two-dimensional imaging devices, The first step is to position a calibration jig having a plurality of point light sources arranged at predetermined intervals from each other, such that a portion of the point light sources are located at the periphery of the imaging range of the two-dimensional imaging device, A second step involves imaging the point light source of the calibration jig using the plurality of two-dimensional imaging devices, In the second step, the difference between the distance between two points of the point light source in the image data of the point light source captured and the distance between two points of the point light source in the calibration jig is determined as an error, it is determined whether the error is less than or equal to a preset threshold, and if the error exceeds the threshold, the orientation of the two-dimensional imaging device is adjusted in the third step. A calibration method for a metal material external dimension measuring device comprising the above.
The calibration method for a metal material external dimension measuring device according to claim 9, wherein the point light source is an LED light source.
The image processing means identifies the position of the long or short side of the metal material within the imaging range from the imaging data of the metal material to be measured, which is captured by the plurality of two-dimensional imaging devices, and determines the distance between the long sides or short sides of the metal material, as described in claim 9, for the calibration method of a metal material external dimension measuring device.
The calibration method for measuring the external dimensions of a metal material according to claim 9 or 11, characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward.
A calibration method for a metal material external dimension measuring device according to any one of claims 9 to 12, wherein the plurality of two-dimensional imaging devices are mounted on a single support.
Calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 13, wherein the central region of the imaging range is a region in which the amount of distortion in the image when the metal material to be measured is imaged is 3% or less.
A calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 14, wherein the central region of the imaging range is an area of 50% or more of the total area of the imaging range.
A calibration method for a metal material external dimension measuring device according to any one of claims 9 to 15, wherein the two-dimensional imaging device is an infrared camera.
A calibration method for a metal material external dimension measuring device according to any one of claims 9 to 16, wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device.

Description

The present invention relates to a method for measuring the external dimensions of a metal material and a method for calibrating a device for measuring the external dimensions of a metal material . Thick steel plates (hereinafter referred to as "thick plates") are produced by adjusting the width dimension of heated steel material through width-extending rolling using a roughing mill and an edging mill, then adjusting the plate thickness through finish rolling using a finish rolling mill, and finally allowing it to cool. In some cases, controlled cooling is performed after finish rolling before allowing it to cool. During width-extending rolling, the steel material extracted from the heating furnace is rotated 90° before reaching the roughing mill, and reverse rolling is performed multiple times with the width direction of the steel material as the rolling direction. Before the end of width-extending rolling, the plate width of the steel material being rolled is measured to confirm that the plate width has reached the target value. Conventional steel shape measurement involved using imaging cameras to photograph the steel before rolling was completed and measuring the plate width from the captured images. Specifically, in conventional steel shape measurement, two one-dimensional cameras with linear fields of view were installed directly above the steel rotation mechanism in front of the roughing mill. Furthermore, a reflective mirror was placed between each one-dimensional camera and the steel rotation mechanism. The reflective mirror was then driven to scan the field of view of one one-dimensional camera in the width direction of the steel while photographing the steel on the steel rotation mechanism. Simultaneously, another reflective mirror was used to scan the field of view of the other one-dimensional camera in the longitudinal direction of the steel while photographing the steel on the steel rotation mechanism. Based on the obtained image data, the dimensions of the steel in both the width and longitudinal directions were measured. In conventional plate width measurement using a one-dimensional camera, a reflective mirror is placed between the camera and the steel material to scan the camera's field of view. However, this reflective mirror becomes a source of error in shape measurement, making accurate shape measurement impossible. Therefore, recently, instead of using a one-dimensional camera with a linear field of view, a two-dimensional camera with a planar field of view has been used to directly capture the planar shape of steel materials with the two-dimensional camera, and a planar shape measuring device has been developed that performs shape measurement based on the obtained image data (Patent Document 1). Japanese Patent Publication No. 2016-194489 Figure 1 is a schematic diagram showing a part of a manufacturing line for thick plates equipped with the metal material external dimension measuring device of the present invention, where (a) is a side view and (b) is a top view.Figure 2 is a perspective view showing the main parts of the metal material external dimension measuring device of the present invention.Figure 3 is a schematic plan view showing the positional relationship between the steel material to be measured, the four two-dimensional imaging devices, and the imaging ranges of the four two-dimensional imaging devices.Figure 4 is a schematic diagram illustrating the distortion aberration in the imaging range of the two-dimensional imaging device according to the present invention.Figure 5 is a schematic plan view of the calibration jig according to this embodiment.Figure 6 is a schematic plan view illustrating the point light source and the distance between the point light sources of the calibration jig shown in Figure 5.Figure 7 is a diagram illustrating the first step of the calibration method, and is a schematic plan view illustrating the positional relationship between the imaging range of the two-dimensional imaging device and the calibration jig.Figure 8 is a schematic plan view illustrating the second step of the calibration method, showing the position of the calibration jig in the image captured by the two-dimensional imaging device.Figure 9 is a flowchart showing the flow of the external dimension measurement method and calibration method for metal materials when performing the verification step.Figure 10 is a schematic plan view of the inspection jig according to this embodiment.Figure 11 is a schematic plan view showing an example of imaging of a calibration jig using four two-dimensional imaging devices.Figure 12 is a schematic plan view showing the positional relationship between the steel material to be measured, the two two-dimensional imaging devices, and the imaging ranges of the two two-dimensional imaging devices.Figure 13 is a schematic plan view showing the positional relationship between the steel material to be measured, the six two-dimensional imaging devices, a