KR20140031138A - Shape inspection apparatus and method of bar steel - Google Patents

Abstract

An object of the present invention is to reliably check the dimensional abnormality of the crude steel being rolled in the crude steel rolling line using an optical method.
The shape inspection apparatus 10 of the crude steel of the present invention is a device for inspecting the shape of the crude steel W being rolled by the rolling mill 7, and irradiates the optical cutting line S so as to intersect with the conveying direction of the crude steel W. Light picked up in the image picked up by the imaging section 12 and the imaging section 12 for picking up the light irradiation section 11, the roughening material W irradiated with the light cutting line S, through the imaging lens 13. The shape detection part 15 which detects the shape of the bar steel W is applied to the cutting line S by applying the principle of triangulation.

Description

SHAPE INSPECTION APPARATUS AND METHOD OF BAR STEEL}

The present invention relates to an apparatus and a method for inspecting the shape of a crude steel being rolled in a crude steel rolling line.

In a crude steel rolling facility (a crude steel rolling line) which manufactures a crude steel such as a bar or a wire rod from a steel strip such as a billet, it is common that a heating furnace, a rough rolling device, an intermediate rolling device, and a finish rolling device are arranged in order from the upstream side. to be. In the rolling line which rolls a wire rod, a water cooling stand, a pinch roll, and a winding device are provided downstream of the finishing rolling apparatus. In the rolling line which rolls a steel bar, a dividing shear, a water chiller, and a cooling bed are provided in order in the downstream of the finishing rolling apparatus.

Regarding the crude steel produced in such a crude steel rolling line, scratches may occur on the surface of the product. Moreover, abnormality of a cross-sectional shape and abnormality (outside a dimension tolerance range) of steel materials may arise. There may be a shape abnormality and a dimension abnormality in the cross section accompanying the occurrence of burrs and the like. If such shape abnormalities or dimension abnormalities exist, they cannot be released as products.

As a method of inspecting the surface flaw generate | occur | produced on the surface of a crude steel material, there exists a technique disclosed by patent document 1, for example.

Patent Literature 1 discloses a method for detecting surface scratches in a rough steel rolling line using an optical method. This patent document is a method of optically detecting defects occurring on the surface of a product in a process of manufacturing a metal material such as steel sheet, steel, or steel pipe by hot rolling, and has an extremely thin oxide on the surface to be inspected. At a location in the present disclosure, a method for detecting surface defects for detecting surface defects is disclosed.

Moreover, as a method of detecting the shape abnormality of a crude steel material, there also exists a technique disclosed by patent document 2, for example. This patent document is provided with a base, a pair of work clamp portions provided on the base and clamped and unclamped a bar to be inspected, and a pair of work clamps provided on the base to move in the axial direction of the bar. A camera stage for photographing the bars of the inspection region between the work clamp portions from above, a light stage provided on the base, moving in the axial direction of the bars in synchronization with the camera stage, and illuminating the bars from below; It is installed in the base, and can be moved back and forth with respect to the bar clamped in the work clamp unit, and the camera stage is in the retracted position during the inspection of photographing the bar in the inspection area, and moves to the forward position with the end of the inspection. With a pair of V blocks to move and support the steel bar in the forward position It is provided in a forward and backward movement block and the said forward and backward movement block, The said steel bar is received by the said V block at the time of the unclamping of the said work clamp part, The said forward position is rotated a predetermined angle in the circumferential direction of the said steel bar, and the inspection of the said steel bar The bar shape inspection apparatus provided with the rocking mechanism which changes a site | part and delivers the said bar to the said work clamp part is disclosed.

Japanese Patent Application Laid-Open No. 2001-242089 Japanese Patent Application Publication No. 2009-115744

By using the technique of patent document 1 mentioned above, it may be possible to detect the flaw which generate | occur | produced on the surface of crude steel manufactured by a crude steel rolling line, etc. However, even if such a technique is used, abnormality in cross-sectional shape of crude steel, abnormality in width dimension, dimensional abnormality with occurrence of burr, etc. cannot be detected.

Although the technique of patent document 2 detects the abnormality of the shape of a crude steel, it does not disclose the technique of performing an off-line inspection technique, but does not disclose the technique of inspecting a crude steel in manufacture in a crude steel rolling line.

Accordingly, an object of the present invention is to provide a technique for reliably inspecting an abnormality in dimensions of a crude steel being rolled in a crude steel rolling line using an optical method in view of the above problems.

In order to achieve the above object, the present invention takes the following technical means.

That is, the shape inspection apparatus of the present invention is a device for inspecting the shape of the steel bar being rolled in the rolling mill, and the optical irradiation unit for irradiating the light cutting line to the steel bar, and the image of the steel material irradiated with the light cutting line through the imaging lens It is characterized by including a imaging part and a shape detection part which detects the shape of a crude steel material by applying the principle of a triangulation method to the optical cut line taken in the image picked up by the said imaging part.

Applicants have developed an apparatus for online inspection of the shape of the hot rolled steel in the steel rolling line, in consideration of the fact that the hot rolled steel is glowing, it is recommended to use an optical sensor of passive type (self-luminescence). Thought. However, in the self-luminous optical sensor, the detection position (coordinate) of both ends of the steel width becomes unstable depending on the temperature of the bar steel, or the position detection and the shape detection become unstable even by the change of the surface state due to the presence of scale or the like. Done From the beginning, there exists also a problem that shape measurement cannot be performed with the optical sensor of a self-luminous system.

Accordingly, the present applicants have come to adopt an active optical sensor in which the sensor itself emits light for measurement. The active optical sensor used in the present invention includes a light irradiation part for irradiating a light cutting line so as to intersect with a transport direction of the bar steel, an image pickup unit for imaging the steel material irradiated with the light cutting line through an imaging lens, The shape detection part which detects the shape of a crude steel material is provided by applying the principle of a triangulation method to the optical cut line image | photographed in the image picked-up.

Preferably, the imaging lens should just be a telecentric lens.

Preferably, the light irradiation part should just be provided with the green laser light source.

On the other hand, when inspecting the shape of the steel bar by using the shape tester of the above-described steel bar, two pieces having a luminance equal to or greater than the background brightness and existing at the most end based on the image acquired by the image capturing unit of the shape tester. A point is extracted as both end position coordinates, the difference of the extracted both end position coordinates is detected as a diameter of a crude steel material, and the shape of a crude steel material is examined based on the detected diameter.

In addition, when the shape of the steel bar is inspected using the shape inspection apparatus of the above-described steel bar, in the image acquired by the image capturing unit of the shape inspecting device, fitting to the original equation is performed by the least square method. Based on the formula of the circle obtained by the fitting, the diameter of the bar steel is obtained, and the shape of the bar steel is examined based on the obtained diameter.

In addition, when inspecting the shape of the steel bar by using the shape tester of the above-described steel bar, two pieces having a luminance equal to or greater than the background brightness and existing at the most end are based on an image acquired by the image capturing unit of the shape tester. A point is extracted as both end position coordinates, and the extracted both end position coordinates are referred to as "measured both end position coordinates", and in the image acquired by the image capturing unit of the shape inspection apparatus, fitting to the original equation is performed by the least square method. From the original equation obtained by the above fitting, both end position coordinates of the bar steel are obtained, and the obtained end position coordinates are originally referred to as "existing end position coordinates" which are coordinates where both end positions should exist, In the case where the difference between the "end-end position coordinates" differs from the allowable value or more, it is determined that there is a shape abnormality of the bar steel. Characterized in that.

Preferably, when performing the fitting, the vertex coordinates of the optical cut line are extracted, and the fitting of the equation of the circle is performed by the least square method using each point coordinate of the optical cut line in a predetermined range from the extracted vertex coordinates. Just do it.

According to the present invention, by using the optical method, it is possible to reliably inspect the shape abnormality and the dimensional abnormality of the crude steel being rolled in the crude steel rolling line.

1 is an overall view of a crude steel rolling line for producing crude steel.
2 shows an outline of a shape inspection apparatus;
3 shows an example of an image picked up;
4 is a view for explaining a method of measuring the width of a steel bar.
FIG. 5 is a diagram for explaining a method for detecting protruding or missing defects. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 is an overall view of a crude steel rolling line 1 for producing crude steel.

As shown in FIG. 1, the crude steel rolling line 1 manufactures crude steel W. As shown in FIG. In addition, the bar steel W manufactured by the bar steel rolling line 1 may be a rod material, or a wire rod may be sufficient as it.

The crude steel rolling line 1 is a heating furnace 2 for heating steel pieces such as billets in order from the upstream side to the downstream side, a rough rolling device 3, an intermediate hot rolling device 4, and a finish rolling device 5 ), The cooling device 6 (water cooling rack) is provided in this order.

The rough rolling apparatus 3, the intermediate | middle heat rolling apparatus 4, and the finishing rolling apparatus 5 are each equipped with the some rolling stand 7, and the rolling stand 7 is rolled for rolling the crude steel W; The roll 8 is provided.

In the crude steel rolling line 1, first, a billet (steel piece) serving as a base of crude steel is introduced into the heating furnace 2 to be heated, and the heated billet is descaled. Then, the descaled steel piece is roughly rolled to a predetermined size by the rough rolling device 3. The rolling rolls 8 of the rough rolling apparatus 3 are HV array, and are rolled, changing a rolling direction alternately. In the intermediate heat rolling device 4 and the finish rolling device 5, the rolling shapes 8 are rolled so that the cross-sectional shape becomes round from an ellipse, and finally the target shape (for example, round shape). Is rolled into. The crude steel W rolled in a round shape is cooled in the cooling device 6, and wound up by the winding device 9 in the case of a wire rod, and cut into a predetermined length by a dividing shear (not shown) in the case of a rod material. do.

Moreover, the shape measuring apparatus 10 is provided in the crude steel rolling line 1 of this invention in order to detect the shape and cross-sectional width dimension (sometimes called steel width) of the crude steel W being rolled. Although the shape measuring apparatus 10 is installed in the exit side of the finishing rolling apparatus 5, for example, an installation place is not limited.

Hereinafter, the shape measuring device 10 will be described in detail.

2 is a diagram schematically showing the configuration of the shape measuring device 10.

The shape measuring device 10 applies a sheet-like or line-shaped laser beam, that is, an optical cutting line S, to the surface of the bar steel W that is rolled and conveyed in the width direction (the direction substantially perpendicular to the conveying direction). The light irradiation part 11 to irradiate is provided. The light irradiator 11 includes a laser projector (not shown) that emits a spot-shaped laser light, and a cylindrical lens (not shown) in which the spot light emitted by the laser projector is incident and condensed with a sheet-shaped laser light. Is made of.

The laser irradiated from the light irradiation part 11 has the width | variety larger than the steel width of the crude steel W, and the wavelength becomes about 532 nm, for example, and it is suitable that it is called a green laser.

Moreover, the shape measuring apparatus 10 has the imaging part 12 which image | photographs the surface of the crude steel W with which the optical cutting line S was irradiated. In the case of this embodiment, the imaging part 12 is comprised with a CCD camera (area camera). The light irradiation part 11 and the imaging part 12 are arrangement | positioning of the light cutting method (triangulation method) which formed the angle (alpha).

The imaging lens 13 provided in the imaging section 12 is a telecentric lens. A telecentric lens is a lens whose optical axis and chief ray can be regarded as parallel on one side of the lens, and when the image is taken using a telecentric lens, the subject size changes even if the subject moves back and forth or shakes up and down. It does not have such features. The front face of this telecentric lens may be provided with an optical filter 14 (interference filter) that transmits only the green laser irradiated from the light irradiation unit 11.

3 shows an example of the captured image. The upper left portion of the image is the origin, and the X axis in the horizontal direction and the Y axis in the vertical direction are set. As is apparent from the image of FIG. 3, the installation location of the light irradiation section 11 and the imaging section 12 and the imaging lens (1) so that the light cutting line S irradiated over the entire steel width direction of the bar steel W are taken. 13) and the focal length are set.

The image including the optical cut line S picked up by the imaging section 12 is sent to the shape detecting section 15. The shape detection unit 15 introduces the sent image into the frame memory and performs processing such as binarization on the image captured by the imaging unit 12 using the frame memory and a computer in which the frame memory is incorporated. Only the cutting line S is extracted.

The information (image data) of the extracted optical cut line S is sent to a processing unit of a computer constituting the shape detecting unit 15. The computer is a personal computer or the like. In this computer, the height distribution (shape) and the steel width (cross-sectional width) on the surface of the crude steel W are applied by applying the principle of triangulation to the extracted optical cut line S. Dimensions) are calculated.

By the way, in order to detect the three-dimensional shape of the bar steel W correctly, it is essential to calculate the coordinate of the optical cutting line S correctly. In particular, in order to accurately detect the steel width of the bar steel W, it is necessary to calculate the coordinates of both ends (upper and lower ends) of the light cutting line S accurately.

In the shape detection unit 15 of the present embodiment, the following determination processing (decision processing 1 to determination processing 4) is used to detect the shape abnormality accompanying the accurate measurement of the steel width, the presence of protruding or missing defects, and the like. .

[Decision Processing 1]

First, as the determination process 1, from the image acquired by the imaging part 12, two points which exist in the most end (upper part, lower end part) among the brightness | luminance more than a background brightness | luminance are extracted as both end positions, and both end positions (both end coordinates) The difference of is output as steel width (cross section width). In order to know the steel width accurately, it is preferable to detect the position of both ends on an image with the precision of a subpixel.

[Decision Processing 2]

In addition, as the determination process 2, as shown to Fig.4 (a), the search area of 100 pixels x 100 pixels is set in the vicinity of the origin of the image acquired by the imaging part 12 (FIG. 4). The rectangle described in (a) as (1)]. The luminance value obtained by calculating the average value of luminance in this rectangular area is made into background luminance (threshold value). Thereafter, for each scan line along the X direction, the pixel position having the luminance equal to or greater than the calculated background luminance and becoming the maximum luminance on one line is searched. This scanning is performed in order in the Y direction (the process described as (2) in FIG. 4 (b)).

Next, with respect to the pixel position searched in each scan line, the pixel position detected in the neighboring scan line is recognized as a block of line figures, and the length in the Y direction of the block of line figures is 900, for example. What is continued more than a pixel is set to the optical cutting line S of a bar steel material. The pixel position of the both ends of the obtained optical cutting line S is calculated | required as an up-down position. Also in this case, it is preferable to obtain the coordinate position by the sub pixel order.

According to the determination process 1 and the determination process 2 mentioned above, since the cross-sectional width is calculated only by the geometrical conditions (existing range of the crude steel W), regardless of the surface state of the crude steel W, it is rolling. The steel width of the crude steel W can be obtained remotely and accurately.

In addition, in the case of the steel bar W being rolled, even if it is difficult to detect the positional coordinates, vibrations, or the like, and it is difficult to stably detect both end coordinate positions, in the shape measuring apparatus 10 of the present invention, the imaging lens 13 Since it is made of a telecentric lens, the size of the steel bar W does not change even when the steel bar W moves back and forth or shakes up and down. Therefore, the steel width of the crude steel W can always be obtained accurately.

By the way, in the case of the rolling steel W being rolled, both ends are curved, and it cannot be said that the optical cutting line S corresponding to both ends can be extracted cleanly. A method of accurately detecting the cross-sectional dimension in response to such a situation will be described as the determination process 3.

[Decision Processing 2 ']

By the way, the method described below can also be employ | adopted as a process of obtaining the steel width of the crude steel W being rolled instead of the determination process 2 (decision process 2 ').

First, similarly to the determination process 2, in FIG. 4A, the luminance value obtained by calculating the average value of luminance in the rectangular region that is the search region is set as the background luminance (threshold value). Thereafter, for every scan line along the X-direction, all pixels having a luminance equal to or greater than the calculated background luminance are extracted, and an average luminance value is obtained for all the extracted pixels. This scanning is performed in order in the Y direction.

Next, with respect to the array (data string) of the average luminance values of the scanning players in the Y direction, differential (differential) is performed by neighboring luminance values, and the coordinates having the largest derivative value are extracted, and the extracted coordinates (up and down) are obtained. Two coordinates) are used as coordinate values at both ends of the optical cut line S. FIG. The steel width of the bar steel W can be calculated | required by obtaining the up-down difference of the obtained coordinate of both ends.

[Decision Processing 3]

As the determination process 3, as shown to FIG. 4B, the vertex coordinate (highest point) of the optical cut line S is extracted in the image acquired by the imaging part 12. FIG. Then, using the point coordinates of the optical cut line S in the range of ± β angle (β is a maximum of 90 °, experimentally determined and set) from the extracted vertex coordinates, the equation of the circle (X ² + Y ² = The fitting is performed by the least square method for R ² ). Based on the original equation obtained by this fitting operation, the most reliable 2R (diameter), ie, the steel width, is determined.

In addition, by setting the value of β to be small (about β = 45 to 60 °), it is possible to obtain the steel width value with higher accuracy.

[Decision Processing 4]

By the way, when monitoring the shape of the bar steel W after rolling, it cannot be completely managed only by the width of the steel, but it is "protruded (the material of the bar steel W protrudes to one side") and "deficiency [bar steel W A part of) becomes concave]. "(See FIG. 5). When the central axis of the steel bars passing through the rolling mill is shifted, when the protrusion amount and the defect amount are about the same, there is no change in the steel width value, but it is not suitable as a rolled shape (NG product).

Therefore, in the shape measuring part of this embodiment, determination process 4 as shown in FIG. 5 is performed.

In the determination process 4, first, the steel width is calculated | required using the determination process 1 or the determination process 2, and both position position coordinates (upper-end coordinates and lower-end coordinates) of the crude steel W are calculated and recorded. Let both end position coordinates obtained by determination processing 1 and 2 be "measured both end position coordinates."

In addition, fitting is performed based on the least square method using decision processing 3 to obtain the original equation (X ² + Y ² = R ² ). From the obtained equation of the circle, the steel width is determined and the position coordinates of both ends of the crude steel W are obtained. Both end position coordinates obtained in the determination process 3 can be considered as "coordinates in which both end positions must exist."

In addition, the coordinates (X, Y) (coordinate values obtained in the determination process 3) where the original both end positions should exist, and the measured both end position coordinates (X ', Y') (coordinate values obtained in the determination processes 1 and 2) When it differs more than a tolerance, it determines with a shape abnormality.

Specifically, when the measured both end coordinate positions X 'and Y' are originally outside the both end positions X and Y, it is determined as "deviated." In addition, when the measured both end positions X 'and Y' are originally located inside the both end positions X and Y, it is determined as "defective" and is determined to be defective.

As described above, the telecentric lens uses the light irradiation part 11 for irradiating the light cutting line S to intersect the transport direction of the bar steel W, and the steel material W irradiated with the light cutting line S. The shape of the bar steel W is detected by applying the principle of triangulation to the image capturing section 12 picked up through 13 and the optical cut line S taken in the image picked up by the image capturing section 12. By using the shape inspection apparatus 10 of the crude steel W provided with the shape detection part 15, the abnormality of the dimension of the crude steel W rolling by the crude steel rolling line 1 can be reliably inspected.

It is also to be understood that the embodiments disclosed herein are by way of illustration and not of limitation in all respects. In particular, in the presently disclosed embodiment, matters which are not explicitly disclosed, for example, operating conditions, operating conditions, various parameters, dimensions, weights, volumes, etc. of the components do not deviate from the ranges normally performed by those skilled in the art. The value which can be easily assumed by those skilled in the art is adopted.

1: crude steel rolling line
2: heating furnace
3: rough rolling device
4: medium heat rolling device
5: finish rolling device
6: Cooling unit
7: rolling stand
8: rolled roll
9: winding device
10: shape measuring device
11: light irradiation part
12:
13: imaging lens
14: optical filter
15: shape detection unit
W: crude steel
S: optical cutting line

Claims (7)

It is a device for inspecting the shape of the crude steel being rolled in the crude steel rolling line,
A light irradiation part for irradiating a light cutting line to intersect the crude steel material;
An imaging unit which picks up the crude steel to which the optical cutting line is irradiated through an imaging lens;
And a shape detecting unit which applies a principle of triangulation to the optical cut line taken in the image picked up by the image pickup unit, and detects the shape of the steel bar. The shape inspection apparatus according to claim 1, wherein the imaging lens is a telecentric lens. The shape inspection apparatus according to claim 1 or 2, wherein the light irradiation part includes a green laser light source. When inspecting the shape of the crude steel using the shape inspection apparatus of the crude steel according to claim 1 or 2,
Based on the image acquired by the imaging part of the said shape inspection apparatus, two points which have brightness more than a background brightness and exist in the most end are extracted as both end position coordinates, and the difference of the extracted both end position coordinates is detected as the diameter of a steel-steel material. And inspecting the shape of the crude steel material based on the detected diameter. When inspecting the shape of the crude steel using the shape inspection apparatus of the crude steel according to claim 1 or 2,
In the image acquired by the imaging part of the said shape inspection apparatus, fitting to the formula of a circle is performed by the least square method, the diameter of a crude steel material is calculated | required based on the formula of the circle obtained by the said fitting, and based on the calculated | required diameter The shape inspection method of a crude steel material characterized by inspecting the shape of the crude steel material. When inspecting the shape of the crude steel using the shape inspection apparatus of the crude steel according to claim 1 or 2,
Based on the image acquired by the imaging part of the said shape inspection apparatus, two points which have brightness more than a background luminance and exist in the most end are extracted as both end position coordinates, and let the extracted both end position coordinates be "measured both end position coordinates". ,
In the image acquired by the imaging part of the said shape inspection apparatus, fitting with respect to a circle formula is performed by the least square method, the position coordinates of both ends of a crude steel material are calculated | required from the equation of the circle obtained by the said fitting, and the calculated both end position coordinates are Originally, it is assumed that "end-end position coordinate which exists" which is the coordinate which both end positions should exist,
When the difference between obtained "measured both end position coordinates" and "existent both end position coordinates" differs more than an allowable value, it determines with the shape abnormality of a crude steel material, The shape inspection method of the crude steel material characterized by the above-mentioned. The method of claim 5, wherein when performing the fitting, the vertex coordinates of the optical cut line are extracted, and each point coordinate of the optical cut line in a predetermined range is extracted from the extracted vertex coordinates, and the expression of the circle is determined by the least square method. A shape inspection method of a steel bar, characterized in that fitting is performed.

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