JPH06201330A - Seamless steel pipe length measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To measure the length of seamless steel pipe after rolling with high accuracy. [Structure] A detector 12 for detecting one pipe end of a seamless steel pipe 11 traveling along a conveyor line, and when one pipe end of the seamless steel pipe 11 is detected by the detector 12, the detection timing is changed. A CCD camera 13 having a random shutter function for randomly and two-dimensionally capturing the other pipe end of the seamless steel pipe, and the two-dimensional image data captured by the CCD camera 13 is taken in The screen of is divided into appropriate sections, and the part where the total value of the brightness of the pixels in each section is a certain value or more is recognized as a steel pipe, and the endmost continuous section in the longitudinal direction is determined to be the other pipe end of the steel pipe. The image processing unit 14a and the calculation unit 14b that obtains the length of the steel pipe based on the other pipe end of the steel pipe determined by the image processing unit 14a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a length measuring device for a seamless steel pipe after rolling.

[0002]

2. Description of the Related Art Conventionally, as a measuring device for measuring the length of a seamless steel pipe after rolling, for example, JP-A-57-13460 is used.
There is known one in which a steel pipe is measured by using a one-dimensional CCD camera or a camera having an image sensor built therein as shown in Japanese Patent Publication No.

Here, when measuring the length of a seamless steel pipe after rolling, since the temperature of the steel pipe is 700 ° C. or higher, a method of detecting the steel pipe itself as a light source without separately providing a light source is also used. Came. That is, as shown in FIG. 5, one end (for example, the tip) of the running steel pipe 1 is detected by a detector 2 (for example, a laser projecting / receiving type), and the other end of the steel pipe 1 is detected by the one-dimensional CCD camera 3 at that timing. Is taken, and the image data is taken into the arithmetic processing unit 4 to calculate the length of the steel pipe 1.

In this case, in order to determine the rear end of the steel pipe 1 in the arithmetic processing unit 4, as shown in FIG. 6, the portion where the brightness of the one-dimensional image data is a certain value or more is determined to be the steel pipe, and the length of the steel pipe 1 is long. The endmost portion in the direction (circle in FIG. 6) is determined as the rear end.

[0005]

However, such a conventional seamless steel pipe length measuring device has the following problems.

The pipe end of the seamless steel pipe after rolling has a shape as shown in FIG. 7 due to the characteristics of the rolling mill, but the field of view of the one-dimensional CCD camera 3 is, for example, as shown in A and B of FIG. .
Therefore, in the CCD camera 3, whether the part of the visual field A or the part of the visual field B is detected is determined by the steel pipe 1 and the one-dimensional CCD.
It depends on the relative position of the camera 3 and is not constant.
That is, the length measurement result in the field of view A is a, and the length measurement result in the field of view B is b, so that the one-dimensional CC at that time is
Due to the difference in the relative position between the D camera 3 and the steel pipe 1, there is a large difference in the measurement result, which causes a measurement error. Incidentally, this difference may be 300 mm or more.

Therefore, in measuring the length of a seamless steel pipe, the shape of the pipe end as described above is more remarkable at the rear end than the front end in the rolling direction of the steel pipe. Need to measure length.

The present invention provides a seamless steel pipe length measuring device capable of eliminating the above-described length measurement error of the seamless steel pipe and measuring the length of the seamless steel pipe after rolling with high accuracy. With the goal.

[0009]

In order to achieve the above-mentioned object, the present invention detects the one end of a seamless steel pipe running along a conveyor line, and the detection means for detecting the seamless steel pipe. When one of the pipe ends is detected, an image pickup means having a random shutter function for two-dimensionally picking up the other pipe end of the seamless steel pipe at a random detection timing, and an image pickup means for picking up images by the image pickup means. Dimensional image data is captured and the screen of this image data is divided into appropriate sections. The part where the total value of the brightness of the pixels in each section is a certain value or more is recognized as a steel pipe, and the most continuous in the longitudinal direction. An image processing unit that determines the end section as the other pipe end of the steel pipe, and a calculation unit that calculates the length of the steel pipe based on the other pipe end of the steel pipe determined by the image processing unit. is there.

[0010]

In the seamless steel pipe length measuring device having such a structure, the image data obtained by the two-dimensional image pickup means is divided into appropriate sections by the image processing means and the brightness of the pixels in each section is divided. The part where the total value of is equal to or greater than a certain value is recognized as a steel pipe, and the endmost continuous section in the longitudinal direction is determined to be the other pipe end of the steel pipe, and the calculation means based on the other pipe end of this steel pipe. By determining the length of the steel pipe, the pipe end shape,
The length of the steel pipe can be accurately measured without being affected by the relative position of the camera and the steel pipe.

[0011]

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

FIG. 1 shows a structural example of a length measuring device for a seamless steel pipe according to the present invention. In FIG. 1, reference numeral 11 denotes a steel pipe which has been rolled by a rolling mill (not shown) and has a high temperature of 700 ° C. or higher that travels at a constant speed on a conveyor line. Reference numeral 12 is a detector for detecting the tip of the steel pipe 11, for example, a laser projection / reception type detector, and 13 is this detector 12.
When the tip of the steel pipe 11 is detected by the
-Dimensional CC for capturing images by random shutter method
It is a D camera. Reference numeral 14 denotes an image processing unit 14a that captures image data of the two-dimensional CCD camera 13 at the timing when the detection signal of the detector 12 is input, and performs image processing on the image processing unit 14a and the data processed by the image processing unit 14a. This is an arithmetic processing device including an arithmetic unit 14b for calculating the length.

The two-dimensional CCD camera 13 has a relatively large number of pixels as compared with the one-dimensional CCD camera. For example, the one-dimensional CCD camera has 2048 pixels, whereas the two-dimensional CCD camera 13 has 510 pixels. × 492 = 250
There are 920 pixels. Therefore, the time required to read the image data after imaging is longer in the two-dimensional CCD camera 13 than in the one-dimensional CCD camera. Therefore, in the case of the one-dimensional CCD camera, the image data reading time can be ignored. In the case of the two-dimensional CCD camera 13, the reading time of image data cannot be ignored. Therefore, a camera having a random shutter function is used to accurately capture a two-dimensional image at random timing when the tip of the steel pipe 11 is detected by the detector 12. Next, the operation of the seamless steel pipe length measuring device configured as described above will be described.

When the detector 12 detects the tip of the steel pipe 11 while the steel pipe 11 is being rolled along a conveying line after being rolled by a rolling mill (not shown), the detection signal is output. Is input to the arithmetic processing unit 14, and the steel pipe 11 is imaged by the two-dimensional CCD camera 13 at that timing. In this case, a two-dimensional CCD
As described above, the camera 13 randomly picks up an image of the steel pipe 11 at the timing of detecting the front end of the steel pipe by the random shutter function, and the image data thereof is taken into the image processing unit 14a of the arithmetic processing unit 14 and image-processed.

Here, the procedure of processing the image data in the image processing section 14a will be described with reference to FIG. 2. First, the screen is divided into equal intervals (a predetermined number of pixels) in the radial direction of the steel pipe 11, and The steel pipe 11 is also divided into equal intervals (a predetermined number of pixels) in the longitudinal direction perpendicular to the radial direction (S1). Here, the size of the interval in the radial direction and the longitudinal direction is set to a size that does not affect the measurement accuracy, for example, 20 mm. Next, the total value of the brightness of the pixels of each section divided as described above is obtained (S2), and the part where the total value of the brightness is a certain value or more is recognized as a steel pipe (S3). Then, as shown in the figure, the endmost continuous section in the longitudinal direction is recognized as the pipe end (S4).

When the position information of the rear end of the steel pipe 11 recognized by the image processing unit 14a is input to the calculating unit 14b, the calculating unit 14b detects the position information of the rear end and the known tip detector 12. The length of the steel pipe 11 is obtained by executing a predetermined calculation from the position information of.

In the embodiment described above, the image data obtained by the two-dimensional CCD camera 13 is processed, the pipe end shape of the steel pipe 11 is recognized by the section of the two-dimensional image, and then the length of the steel pipe 11 is measured. Therefore, the steel pipe 1 is not affected by the pipe end shape, the relative position of the camera and the steel pipe, and the like.
It is possible to accurately measure the length of No. 1, for example, the length of the most protruding portion in the longitudinal direction, and it is possible to recognize the pipe end shape of the steel pipe 11 as a secondary effect.

Here, a method of recognizing a defective portion of the shape of the pipe end will be described. In FIG. 4, the total value in the radial direction of the luminance of the pixels of the section of the steel pipe is obtained, and the portion where the total value is less than 90% of the steady value is the defective shape portion (FIGS. 3 and 4). .

Further, since the random shutter mechanism provided in the two-dimensional CCD camera 13 captures the image data of the rear end of the steel pipe 11 at a random timing for detecting the front end, it is taken into the image processing unit 14a. The fact that the number of pixels of the two-dimensional CCD camera 13 is large and it takes time to read the image data does not affect the length measurement accuracy. The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.

[0020]

As described above, according to the present invention, the length of the seamless steel pipe after rolling can be measured with high accuracy. That is, the variation of the measurement accuracy of the conventional device is about 300 mm at the maximum, whereas the accuracy of about 50 mm is guaranteed by this device.

Further, feedback control of the rolling mill based on the accurate length measurement result can improve the rolling control accuracy, so that the retention can be expected to be improved, and the defective portion of the pipe end shape can be quantitatively evaluated. By doing so, it can be expected to improve the yield by reducing the allowance allowance in anticipation of defective pipe end shape of the steel pipe material.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a length measuring device for a seamless steel pipe according to the present invention.

FIG. 2 is a diagram showing a processing procedure of image data in an image processing unit in the embodiment.

FIG. 3 is a diagram showing an added value of radial luminance in the image processing unit of the embodiment.

FIG. 4 is a diagram showing the shape of a steel pipe recognized by a section in the image processing unit.

FIG. 5 is a configuration diagram showing a conventional seamless steel pipe length measuring device.

FIG. 6 is a diagram for explaining the determination of the pipe end recognized from the characteristics of the rolling mill in the conventional length measuring device.

FIG. 7 is a view showing a shape of a pipe end of a steel pipe.

[Explanation of symbols]

11 ... Seamless steel pipe, 12 ... Detector, 13 ... Two-dimensional CCD camera, 14 ... Arithmetic processing unit, 14a ... Image processing unit, 14b ... Arithmetic unit.

Claims (1)

[Claims] 1. A detection means for detecting one pipe end of a seamless steel pipe traveling along a conveying line, and a random detection timing when one pipe end of the seamless steel pipe is detected by the detection means. An image pickup unit having a random shutter function for two-dimensionally picking up the other pipe end of the seamless steel pipe, and the two-dimensional image data picked up by this image pickup unit is taken in, and a screen of this image data is displayed. Image processing that divides into appropriate sections and recognizes the part where the total value of the brightness of the pixels in each section is a certain value or more as a steel pipe, and determines the endmost continuous section in the longitudinal direction as the other pipe end of the steel pipe A seamless steel pipe length measuring device comprising: a means for calculating the length of the steel pipe based on the other end of the steel pipe determined by the image processing means.