JPH05240620A - Instrument for measuring outer diameter and wall thickness of pipe - Google Patents

Abstract

PURPOSE:To reduce the size and manufacturing cost and improve the detection accuracy of the instrument. CONSTITUTION:The end face of a seam-welded steel pipe P is irradiated with light rays from projectors 152, 152, 152, and 152 and the two-dimensional pictures of the irradiated areas are taken with TV cameras 151, 151, 151, and 151. A binarization processing section 153 binarizes the two-dimensional pictures of the end face and the other part of the pipe P from the two-dimensional pictures taken with the cameras 151, 151, 151, and 151. Based on the binarized two-dimensional pictures, a wall thickness measuring section 155 and an outer diameter measuring section 156 respectively find the wall thickness and outer diameter of the pipe P.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a device for measuring the outer diameter and wall thickness of a pipe.

[0002]

2. Description of the Related Art Conventionally, the outer diameter and wall thickness of a manufactured pipe have been measured manually by an operator using a dimension measuring instrument such as a tape measure and a micrometer, and based on the measurement result. Quality control is done. However, such a measuring method has a problem that it requires a lot of manpower for the measuring work and the measuring efficiency is low. Therefore, the measuring for automatically measuring the outer diameter and the wall thickness of the pipe has been developed. ..

As such measuring devices, the following two types of devices have been disclosed. In the first conventional measuring device (Japanese Patent Laid-Open No. 51-81641), a pair of levers is moved in the radial direction of the pipe for each of a pair of carriages that are provided to move forward and backward with respect to both ends of the pipe. An outer diameter measuring unit for measuring the outer diameter of the pipe, and a lever each having a lever facing the lever, and a wall thickness measuring unit for measuring the wall thickness of the pipe by sandwiching the pipe with the facing lever, The outer diameter and the wall thickness of the pipe were mechanically measured based on the movement of the lever in the outer diameter measurement portion and the wall thickness measurement portion.

In the second conventional measuring device (Japanese Utility Model Laid-Open No. Sho 63-19207), a pair of ultrasonic probes are arranged in the direction orthogonal to the tube axis in a non-contact manner with the tube. Ultrasonic waves were generated from the probe, and the outer diameter and wall thickness of the tube were measured based on the detection results of the reflected waves.

[0005]

However, the above-mentioned first problem
In the measuring device described in (1), since the outer diameter and the wall thickness of the pipe are mechanically measured, the structure of the device is complicated and therefore the manufacturing cost is high, and the moving range of each of the levers is limited. Therefore, there is a problem that the range of the size of the pipe to be measured is limited.

Further, in the above-mentioned second measuring device, unless the positional relationship between the tube and the ultrasonic probe is properly adjusted, a good precision measurement result cannot be obtained, so that the positional relationship is adjusted. Therefore, there is a problem that the complexity becomes complicated and increases in size, and the measurement accuracy of this device is lower than the measurement accuracy of the micrometer.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pipe outer diameter / wall thickness measuring device which is small in size, inexpensive, and has good measurement accuracy. ..

[0008]

[Means for Solving the Problems] Outer diameter of a pipe according to the present invention
The wall thickness measuring device is a device for measuring the outer diameter and the wall thickness of a pipe, and individually irradiates light to each of predetermined regions radially opposed to each other on the end surface of the pipe to be measured through the axial center of the pipe. Means, an image pickup means for two-dimensionally picking up each area irradiated by the means, and a two-dimensional image picked up by the image pickup means is binarized into an end face of the tube and other portions 2 A binarizing unit, a unit for obtaining the outer diameter of the pipe based on the two-dimensional image binarized by the binarizing unit, and a pipe based on the two-dimensional image binarized by the binarizing unit. And a means for determining the wall thickness.

[0009]

In the present invention, the light-irradiated area is two-dimensionally imaged, and the imaged two-dimensional image is binarized on the end surface of the tube and the other portion. The converted two-dimensional image shows a two-dimensional image of the end face of the tube. If such a two-dimensional image is two-dimensionally coordinated, the wall thickness of the tube can be geometrically determined in each imaging region. Further, by the above-mentioned coordinate calculation, the radius of the outer diameter of the pipe is geometrically obtained in each imaging region, and the outer diameter of the pipe obtained in each of the predetermined regions radially opposed to each other via the axial center of the pipe is calculated. Radius The diameter of the outer diameter of the pipe is determined by adding the radii.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing a production line of an electric resistance welded steel pipe to which the pipe outer diameter / wall thickness measuring device according to the present invention (hereinafter referred to as the present device) is applied.

In the figure, reference numeral 1 is a forming roll for bending a steel strip B into a cylindrical shape to obtain an open pipe O. On the downstream side of the line of the forming roll group 1, both side edges of the open pipe O are abutted. A welder for welding to obtain the electric resistance welded steel pipe P, a water cooling tank for cooling the welded electric resistance welded steel pipe P, a sizer roll group for shaping the electric resistance welded steel pipe P, a position of a seam portion of the electric resistance welded pipe P A seam position detecting device for detecting 5, a cut-off machine for cutting the electric resistance welded steel pipe P into a predetermined length 6, a table 7 for sequentially transmitting the cut electric resistance welded steel pipe P to a conveyor 8 described later, and an electric current sent from the table 7. A conveyor 8 that conveys the sewn steel pipe P to the downstream side of the line, a strainer 9 that is arranged in the middle of the convey path of the conveyor 8 and that corrects the bend of the electric resistance welded steel pipe P, and a bended electric resistance welded steel pipe P that will be described later. Sequentially send to conveyor 12 Chamfering machine 11, 11 for processing Buru 10, both end portions of the electric resistance welded steel pipe P sent to the table 10 on the table
A conveyor 12 that conveys the electric resistance welded steel pipe P sent from 10 to the downstream side of the line, and is arranged in the middle of the conveyance path of the conveyor 12,
Eddy current flaw detector 13 for inspecting the surface of the electric resistance welded steel pipe P, table 14 for sequentially sending the surface inspected electric resistance welded steel pipe P, dimensions for measuring the outer diameter and wall thickness of the end of the electric resistance welded steel pipe P on the table 14. The measuring devices 15, 15 are arranged in this order.

In the production line of electric resistance welded steel pipe having such a structure, the strip steel B is fed in the direction shown by the white arrow in the drawing from the upstream side of the line to the downstream side of the line. The steel B is passed through the forming roll group 1 and becomes an open pipe O which is bent in a cylindrical shape with its both side edge portions facing each other. Then, the open pipe O is welded to the welder 2 at both side edge portions thereof, and the both side edge portions thereof are heated and melted by resistance heat and abutted and welded to form an electric resistance welded steel pipe P. The electric resistance welded steel pipe P that has been butt-welded in this way is cooled in the water cooling tank 3, and the beads inside and outside the pipe are cut by a cutting device (not shown).

The electric resistance welded steel pipe P is made up of the sizer roll group 4
While suppressing the outer diameter variation, the position of the seam portion is detected by the seam portion position detecting device 5, and the detected seam portion is flaw-detected by an ultrasonic flaw detector (not shown). After that, the electric resistance welded steel pipe P is shaped into a predetermined outer diameter by the sizer roll group 4, and cut into a predetermined length by the cut-off machine 6.

The bending of the electric resistance welded steel pipe P is suppressed by the strainer 9, and both ends thereof are machined by the chamfering machines 11, 11. After that, the surface of the electric resistance welded steel pipe P is inspected by the eddy current flaw detector 13, and the dimension measuring devices 15, 15 are used.
Sent to.

Next, the structure of the dimension measuring devices 15 and 15 will be described. Since the dimension measuring devices 15 and 15 have the same configuration, one dimension measuring device 15 will be described below as a typical example. FIG. 2 is a schematic diagram showing the arrangement state of the camera and the light projecting device of the dimension measuring device 15,15 when the electric resistance welded steel pipe P is viewed from the side, and FIG. 3 is a schematic diagram showing the camera view of the dimension measuring device 15,15. It is a figure.

As shown in FIG. 2, in the vicinity of the end portion of the electric resistance welded steel pipe P, the circumference of the end face of the electric resistance welded steel pipe P is substantially circumferentially.
Four television cameras 151, 151, 151, 151 for individually imaging four regions 90 degrees apart from each other and four projectors 152, 152, 152, 152 for individually illuminating the four regions are provided. Each of the television cameras 151, 151, 151, 151 has imaging areas Z, Z, which are separated by approximately 90 degrees in the circumferential direction on the circumference of the end face of the electric resistance welded steel pipe P, as indicated by the broken line in FIG.
Has Z, Z.

FIG. 4 is a block diagram of the dimension measuring device 15, 15. The image pickup signals of the television cameras 151, 151, 151, 151 are supplied to a signal processing device 150 for obtaining measured values of the outer diameter and wall thickness of the end portion of the electric resistance welded steel pipe P by performing signal processing such as image processing. The data of the measured values of the outer diameter and the wall thickness obtained by the signal processing device 150 are output as display data and recording data.

The signal processing device 150 includes television cameras 151, 15
A binarization processing unit 153 that binarizes an image captured by 1,151,151 according to its brightness, a threshold storage unit 154 that stores a threshold value of the brightness for the binarization, and a binarization process. Wall thickness measuring unit 15 for obtaining the wall thickness of the end of the electric resistance welded pipe P from the image 15
5 and an outer diameter measuring unit 156 for obtaining the outer diameter of the end portion of the electric resistance welded steel pipe P from the binarized image.

Next, the dimension measuring device configured as described above
The operation of 15 will be described. TV camera 151,151,151,
The imaging signal of 151 is given to the binarization processing unit 153 in the signal processing device 150. The binarization processing unit 153 is previously provided with a threshold value of luminance for binarization from the threshold value storage unit 154.
The image of the electric resistance welded steel pipe P imaged at 151, 151, 151, 151 is binarized based on the threshold value into the end face of the electric resistance welded steel pipe P and the other portion based on the threshold value, and the end face of the electric resistance welded steel pipe P is displayed. The binarized image thus obtained is obtained.

The binarized image data (hereinafter referred to as binarized image data) as described above is used for the wall thickness measuring unit 15
5, the wall thickness measuring unit 155 determines the wall thickness of the end portion of the electric resistance welded steel pipe P based on the binarized image data by the method described below. After that, the binarized image data is given to the outer diameter measuring section 156, and the outer diameter measuring section 156 uses the method described below to perform the binarized image data on the electric resistance welded steel pipe P.
Find the outer diameter of the end of.

FIG. 5 is a schematic diagram showing a binarized image for explaining the wall thickness measuring method in the wall thickness measuring section 155. Of the TV cameras 151, 151, 151, 151, as an example, the image of the TV camera 151 arranged at the top is taken. 2 shows a binarized image based on.

In the figure, W is a window showing the measuring region of the outer diameter and the wall thickness. This window W is 4 in the imaging area.
The area is designated by the coordinates of points, and the horizontal direction of the binarized image is the X axis and the vertical direction is the Y axis.

When measuring the wall thickness, the radial direction of the electric resistance welded steel pipe P on the binarized image is defined as the wall thickness measurement direction based on the known position of the axis O _P of the electric resistance welded steel pipe P. Stipulated 2
A plurality of wall thicknesses (length from the inner peripheral surface to the outer peripheral surface) t are measured at a predetermined angular pitch in the circumferential direction on the quantized image. In the measurement of the thickness t, the coordinate points of the outer peripheral surface on the binary image (X _O, Y _O) and the coordinate point of the inner peripheral surface (X _I, Y _I)
The distance between and is determined, and this distance is used as the measured value of the wall thickness t. Then, the maximum value t _max of the measurement results of these wall thicknesses t
And the minimum value t _min . The maximum value t _max and the minimum value t _min of such a wall thickness t are determined by the other television cameras 151,
The binarized image obtained by picking up the images 151, 151 can be obtained by the same method as described above.

FIGS. 6 (a) and 6 (b) are schematic views showing a binarized image for explaining the outer diameter measuring method in the outer diameter measuring section 156. As an example of the outer diameter measuring method, FIG. The binarized image based on the image picked up by the TV camera 151 arranged at the top is shown in (a), and the binarized image based on the image picked up by the TV camera 151 arranged at the bottom is shown in FIG. 6 (b). .. 6 that are the same as those in FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted.

When measuring the outer diameter, as shown in FIG. 6 (a), the distance from the axial center of the electric resistance welded steel pipe P on the binarized image based on the image picked up by the television camera 151 arranged at the uppermost portion. Of the coordinate point (X _Q1 , Y _Q1 ) of the reference position Q ₁ in which
A plurality of distances h ₁ between the axis component Y _Q1 and the Y-axis component Y _O of the coordinate point (X _O , Y _O ) on the outer peripheral surface are measured at a predetermined pitch in the X-axis direction. Then, the maximum value h _1max of the measurement results of these distances h ₁ is obtained, and this maximum value h _1max is _added to the known distance from the axial _center of the electric resistance welded steel pipe P to the reference position Q ₁ , Radius R _{1 of the} electric resistance welded steel pipe P obtained from the binarized image
Ask for.

Similarly, as shown in FIG. 6B, the distance from the axial center of the electric resistance welded steel pipe P is known on the binarized image based on the image picked up by the television camera 151 arranged at the bottom. Y-axis component Y _Q2 of the coordinate point (X _Q2 , Y _Q2 ) of reference position Q ₂
And a distance h ₂ between the coordinate point (X _O , Y _O ) of the outer peripheral surface and the Y-axis component Y _O are measured at a predetermined pitch in the X-axis direction. Then, the maximum value h of the measurement results of these distances h _2
2max is obtained, this maximum value h _2max is _added to the known distance from the axial _center of the electric resistance welded steel pipe P to the reference position Q ₂ , and the radius R of the electric resistance welded steel pipe P obtained from the binarized image is calculated. Ask for ₂ . It

Then, the radius R ₁ and the radius R ₂ are added to obtain the outer diameter of the electric resistance welded steel pipe P. This is because the topmost TV camera 151 and the bottommost TV camera 151 are opposed to each other in the radial direction of the electric resistance welded steel pipe P, so that the radius R ₁ and the radius R ₂ are This is because the outer diameter in the vertical direction of the electric resistance welded steel pipe P can be obtained by adding them.

Such a measured value of the outer diameter is also applied to the binarized images picked up by the other TV cameras 151, 151 facing each other in the left-right direction in the same manner as described above, whereby the upper and lower sides of the electric resistance welded steel pipe P are measured. The outer diameter in the direction and the outer diameter in the left-right direction are obtained.

Next, the result of actual measurement of the outer diameter and wall thickness of the electric resistance welded steel pipe by using the above-described device of the present invention will be described. In this case, the detection condition is that the ERW steel pipe is carbon steel with an outer diameter of 31.8 mm and a wall thickness of 3.5 mm.
Each of 1,151,151,151 is a high-speed shutter camera (1/700
Second), and the magnification was 2 times, and the illuminance of each of the light projecting devices 152, 152, 152, 152 was about 10,000 lx (irradiation angle about 30 degrees).

FIG. 7 is a graph showing the measurement error when the outer diameter and the wall thickness of the electric resistance welded steel pipe are actually measured using the apparatus of the present invention under the above-mentioned conditions for each measurement position in the circumferential direction of the electric resistance welded steel pipe. The vertical axis represents the measurement error and the horizontal axis represents the measurement position in the circumferential direction. The relationship between these is as follows: the maximum value t _max of the wall thickness t is a white triangle, the minimum value t _min of the wall thickness t is a white square, The outer diameter is indicated by a white circle.

However, the measurement error was obtained by using the measurement value obtained by using a micrometer as a reference value. The measurement positions in this graph are 0 degrees for _the topmost TV camera 151, 90 degrees for the rightmost TV camera 151, _{and the} bottommost TV camera 151.
151 is 180 degrees _{, and} the leftmost TV camera 151 is 270 degrees. Regarding the measurement error of the outer diameter, 0 degree and 180
The measurement error by the TV cameras 151, 151 with respect to degrees is shown at the position of 0 degrees, and the measurement error with the TV cameras 151, 151 between 90 degrees and 270 degrees is shown at the position of 90 degrees.

As is apparent from FIG. 5, the measurement error of the wall thickness and the outer diameter is within ± 10 μm. Further, when the wall thickness and the outer diameter were measured under such conditions using a general conventional apparatus, the following measurement error was obtained. As a typical example, the measurement error of the second conventional measuring device as described above was ± 50 μm. As is clear from the above results, in the device of the present invention, the measurement error is smaller than that in the conventional device, and the detection accuracy is improved.

[0033]

As described above in detail, in the device of the present invention, the end surface of the tube irradiated with light is two-dimensionally imaged, and the two-dimensional image thus taken is displayed on the end surface of the tube and other portions.
Since it is digitized, the binarized two-dimensional image shows a two-dimensional image of the end face of the tube. Such a two-dimensional image should be two-dimensionally coordinated on the two-dimensional image. With this, the outer diameter and wall thickness of the pipe can be accurately determined, and the device is
Since it is composed of a device that irradiates the surface of the tube with light, a device that images the irradiated portion, and a device that performs simple image processing, downsizing of the device can be realized and manufacturing cost can be reduced. It has excellent effects such as realization.

[Brief description of drawings]

FIG. 1 is a schematic view showing a production line of an electric resistance welded steel pipe to which an outer diameter / wall thickness measuring device of the present invention is applied.

FIG. 2 is a schematic diagram showing an arrangement state of a camera and a light projecting device of the dimension measuring device in a state where the electric resistance welded steel pipe is viewed from the side.

FIG. 3 is a schematic diagram showing a field of view of a camera of the dimension measuring device.

FIG. 4 is a block diagram of a dimension measuring device.

FIG. 5 is a schematic diagram showing a binarized image for explaining a wall thickness measuring method in a wall thickness measuring unit.

FIG. 6 is a schematic diagram showing a binarized image for explaining the outer diameter measuring method in the outer diameter measuring unit.

FIG. 7 is a graph showing a measurement error when the outer diameter and the wall thickness of an electric resistance welded steel pipe are actually measured using the device of the present invention for each measurement position in the circumferential direction of the electric resistance welded steel pipe.

[Explanation of symbols]

 151 TV camera 152 Projector 153 Binarization processing unit 155 Wall thickness measuring unit 156 Outer diameter measuring unit P ERW steel pipe

Claims (1)

[Claims] 1. A device for measuring an outer diameter and a wall thickness of a pipe, wherein light is separately irradiated to each of predetermined regions radially opposed to each other on the end face of the pipe to be measured via the axial center of the pipe. Means, an imaging means for two-dimensionally imaging each area irradiated by the means, and a two-dimensional image captured by the imaging means is binarized into an end face of the tube and other portions 2 A binarizing means; a means for obtaining the outer diameter of the pipe based on the two-dimensional image binarized by the binarizing means; and a pipe based on the two-dimensional image binarized by the binarizing means. An outer diameter / wall thickness measuring device for a pipe, comprising: a means for determining a wall thickness.