JPH05196445A - Measuring method for plate thickness of trough-shaped steel plate - Google Patents

Abstract

PURPOSE:To enable simple execution of measurement of the plate thickness of a coil in the shape of a trough to be conducted, without correction of the trough by rolls, before thermal refining rolling is conducted. CONSTITUTION:Three optical triangulation distance-measuring devices 3a, 3b and 3c by a laser light are provided at a prescribed interval L on a truck 2 moving in the width direction of a steel plate 1 in the shape of a trough, and an X-ray generating source 5 of a plate thickness measuring device 4 by an X-ray is juxtaposed for the distance-measuring device 3b at the center. A difference DELTAl is determined from distance l2 and l1 or l3 to the steel plate 1 measured by the distance-measuring device 3b at the center and the distance-measuring device 3a or 3c on one side, and a gradient theta of the steel plate at a place of irradiation by the X-ray is calculated from the interval L between the distance- measuring devices. Subsequently, the plate thickness (t) of the steel plate is computed from a measured value tc of the plate thickness by the plate thickness measuring device 4 and the gradient theta.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the plate thickness of a trough-shaped steel plate after hot rolling.

[0002]

2. Description of the Related Art One of the methods for measuring the plate thickness of a steel sheet is a measuring method using X-rays. This method is performed based on the following equation known as a relational expression between the incident amount I of X-rays on the measurement material and the transmission amount I _o, and the measurement device is arranged in the width direction of the steel sheet fed from the coil. Permeation amount I _o to the steel plate while moving
Is detected to calculate the plate thickness t.

[0003]

[Equation 1] Here, μm: mass absorption coefficient of measuring material ρ: density of measuring material The above method cannot be used for measuring the plate thickness of the steel sheet fed out from the coil. Due to the trough (curvature) peculiar to rolled material, X-rays are transmitted obliquely to the steel sheet at the side edges of the steel sheet, resulting in a measurement result thicker than the actual thickness.
The error from the actual thickness increases as the inclination angle increases, that is, the angle formed with the normal to the steel sheet increases. Therefore, conventionally, the above measurement is performed on the steel sheet after temper rolling, or rolls are arranged before and after the measuring device,
The roll is used to correct the trough of the steel sheet and the measurement is performed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for measuring the thickness of a troughed steel sheet by using X-rays so that the thickness can be easily measured without correcting the trough. It was made as.

[0005]

Therefore, the present invention seeks to correct the plate thickness measurement value by the X-ray by obtaining the gradient of the portion irradiated with the X-ray. That is, according to the present invention, as shown in FIG. 1, the distance measuring apparatus measures distances l ₁ and l ₂ between points a and b on both sides or one side of an area irradiated with X-rays and a reference plane c. The sheet thickness t is obtained from the sheet thickness measurement value t _c obtained from the X-ray transmission amount and the gradient θ after the measurement is performed and the gradient θ between the points is calculated from the given distance L between the points. It was done.

An example of the distance measuring device used in the present invention is an optical triangulation device based on the principle of the optical triangulation method using laser light.

[0007]

EXAMPLE A trolley 2 that moves forwards and backwards in the width direction (direction orthogonal to the feed) of a trough-shaped steel plate 1 extended from a coil is
Optical triangulation device 3a, 3b, 3c using laser light
3 are installed at the same level at a constant interval L, and the central optical triangulation device 3b has an X-ray generation source 5 composed of an X-ray tube which constitutes a known plate thickness measuring device 4 using X-rays. It is lined up.

Although not shown, each optical triangulation device 3a, 3b, 3c is composed of a light emitting element (semiconductor laser) and an optical position detecting element, and laser light emitted from the light emitting element passes through a light projecting lens. Part of the scattered light that is irradiated to the steel plate 1 and reflected by hitting the steel plate 1 passes through the light receiving lens and forms a spot on the optical position detection element. The amount of movement of the spot on the optical position detection element The distance from the optical triangulation device to the irradiation point of the steel plate 1 is measured by the, and the value is input to the computing device 6.

The plate thickness measuring device 4 irradiates the steel plate 1 with X-rays.
Then, the plate thickness of steel plate 1 is calculated from the permeation amount, and the value is the same.
It is adapted to be input to the arithmetic unit 6. That's all
By each optical triangulation device 3a, 3b, 3c
Measured distance to steel plate 1₁, L₂, L₃Is arithmetic equipment
Although the values are input to the storage unit 6, these values are measured by the arithmetic unit 6.
Nakana et al., Measurement with the central optical triangulation device 3b
Value l₂And measurement by the distance measuring device 3a or 3c on one side
Value l₁Or l₃Take in, l ₂ And l₃ (Or l₁)
The difference Δl between the distance measuring device 3b and the distance L between the distance measuring devices
And the gradient θ of the steel plate 1 between 3c and 3a is calculated.

After installing the three optical triangulation devices, as shown in FIG. 3, when the carriage 2 is moved to either the left or right side to measure the plate thickness on the work side or drive side, the left side is measured. Alternatively, the right distance measuring device 3a or 3c
When the distance measuring device 3a is disengaged from the steel plate 1, the distance measuring devices 3b on the center and right sides are separated.
And 3c calculate the slope on the work side, and when the distance measuring device 3c is disengaged, the distance measuring devices 3 on the center and left sides are calculated.
The drive side gradient is calculated from b and 3a.

When the gradient θ of the steel plate at the X-ray irradiation location is obtained as described above, the plate thickness t of the steel plate 1 is then calculated from the plate thickness t _c of the steel plate measured by the plate thickness measuring device 4. It In the above-mentioned embodiment, three distance measuring devices are provided to select the measurement values at three places. In another embodiment, there are two optical triangulation distance measuring devices and an X-ray generation source. It is arranged with a space L on both sides of 5.

[0012]

As described above, according to the present invention, in the method for measuring the thickness of a steel sheet by X-ray, the gradient of the portion irradiated with X-ray is obtained by the distance measuring device to correct the thickness measurement value by X-ray. Since the trough is not corrected by the roll before temper rolling, the plate thickness can be easily measured.

[Brief description of drawings]

FIG. 1 is a schematic diagram according to the method of the present invention.

FIG. 2 is a schematic diagram at the time of measurement by each measuring device.

FIG. 3 is a diagram showing a relationship between a distance measuring device and a work side or a drive side.

FIG. 4 is a schematic diagram in an example.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1 ... Steel plate 2 ... Bogie 3a, 3b, 3c ... Optical triangulation device 4 ... Plate thickness measuring device 5 ... X-ray generation source 6 ... Arithmetic device

Claims (3)

[Claims] 1. A plate thickness measuring device for irradiating a steel plate with X-rays and measuring the plate thickness of the steel plate from the amount of transmission, and a plurality of distance measuring devices for measuring the distance from the reference plane to the steel plate. A distance l ₁ between two points on the steel plate on both sides or one side of the portion irradiated with X-rays by the distance device and the reference plane;
After measuring l ₂ respectively, the slope θ between the two points is calculated from the distance L between the two points, and then the plate thickness t is obtained from the plate thickness measurement value t _c measured by the plate thickness measuring device and the slope θ. A method for measuring the thickness of a trough-shaped steel sheet, characterized in that 2. The distance from the reference plane at three points, namely, the point irradiated with X-rays and the points on both sides of the point measured from the three measured distances, of which the central measured value and either one of them are measured. The method for measuring the plate thickness of a trough-shaped steel sheet according to claim 1, wherein a gradient between a portion irradiated with X-rays and a portion on either side thereof is calculated from the measurement value on the side of. 3. The method for measuring the plate thickness of a trough-shaped steel sheet according to claim 1, wherein the measuring device is an optical triangulation device using laser light.