阅读说明：本技术 一种用于无缝钢管表面三维缺陷检测的无损检测装置 (Nondestructive testing device for detecting three-dimensional defects on surface of seamless steel pipe ) 是由 刘小楠 聂建华 窦曼莉 于 2019-09-30 设计创作，主要内容包括：本发明涉及钢管检测技术领域,尤其为一种用于无缝钢管表面三维缺陷检测的无损检测装置,包括装置本体、电控与喷标系统、工控机与显示部分。本发明,能大大减少现有超声,漏磁,涡流等设备对小点坑的漏报,解决无缝钢管外表面三维缺陷的在线自动检测问题,适宜推广使用。(The invention relates to the technical field of steel pipe detection, in particular to a nondestructive detection device for detecting three-dimensional defects on the surface of a seamless steel pipe. The invention can greatly reduce the missing report of the existing ultrasonic, magnetic leakage, eddy current and other equipment to the small-point pit, solves the problem of online automatic detection of the three-dimensional defect on the outer surface of the seamless steel pipe, and is suitable for popularization and application.)

1. The utility model provides a nondestructive test device for three-dimensional defect detection in seamless steel pipe surface, includes device body, automatically controlled and spouts mark system, industrial computer and display part, its characterized in that: the device body comprises a body mounting base, a three-dimensional sensor mounting base plate up-and-down motion motor, a three-dimensional sensor and a laser shading shell, the electronic control and spray marking system comprises a pipe photoelectric trigger switch, an encoder, an electronic control cabinet, a nozzle and a coating bottle, a three-dimensional sensor up-and-down motion motor controller, a PLC, a four-way three-dimensional sensor trigger controller and a switching power supply are arranged in the electronic control cabinet, and the industrial computer and the display part comprise an industrial computer and a display mouse keyboard.

2. The nondestructive testing device for the surface three-dimensional defect detection of the seamless steel tube according to claim 1, wherein: the device body is provided with four three-dimensional sensors which are arranged on the device body and are vertical to the directions of 45 degrees, 135 degrees, 225 degrees and 315 degrees of the advancing direction of the tube.

3. The use method of the nondestructive testing device for the surface three-dimensional defect detection of the seamless steel pipe is characterized by comprising the following steps of: the nondestructive testing device for the three-dimensional defects on the surface of the seamless steel pipe is specifically operated as follows: when a steel pipe passes through the device body, the incoming pipe photoelectric trigger switch triggers a detection starting signal, the rotary encoder arranged on the roller way triggers the four-way three-dimensional sensor through the trigger controller to simultaneously start to collect the profile data of the surface of the steel pipe, the obtained profile data is transmitted to the industrial personal computer, the profile data is analyzed through a nondestructive detection method, the defects and the positions of the profile data are extracted and fed back to the PLC, and the PLC controls the spray marking system to spray marks.

4. The use method of the nondestructive testing device for the surface three-dimensional defect detection of the seamless steel pipe according to claim 3 is characterized in that: after the device body detects the defect, the PLC is controlled to jet ink by the nozzle, and the relative distance between the ink jet position and the defect position is accurately controlled to be not more than 10 cm by adjusting the ink jet delay time.

5. The use method of the nondestructive testing device for the surface three-dimensional defect detection of the seamless steel pipe according to claim 3 is characterized in that: the nondestructive testing method comprises the following steps:

1) generating an initial two-dimensional image according to the formula pipe diameter, specifically, generating an initial two-dimensional image by using the formula W (2 pi) R/X_RESCalculation, where R denotes the pipe radius of the formulation, X_RESThe resolution of the camera in the X-axis direction is represented, the height of the image is determined by the number of lines of the contour line of the tube body output by the camera, and the color of the image is initialized to be black;

2) according to the input point cloud data, for each row of pipe body contour, utilizing least square methodFitting the ellipse to obtain the center, major axis, minor axis and inclination of the ellipse, and specifically, setting the ellipse equation of any position of the plane as formula x²+Axy+By²+ Cx + Dy + E equals 0, if N (N ≧ 5) measurement points (x) on the ellipse profile are known_i,y_i) (i-1, 2, …, N), based on the principle of least squares, using the formula

3) using the fitted ellipse information, outliers are removed, specifically for each point (x) on the contour₁,y₁) According to the formula

4) projecting the data from which the outliers are removed to obtain a two-dimensional gray image, specifically, according to the formula

5) performing median filtering on the gray level image, specifically, the median filtering can remove salt and pepper noise in the image, assuming that the height of the input image is R and the width is C, for any position (R, C) in the image, R is more than or equal to 0 and less than R, C is more than or equal to 0 and less than C, taking a neighborhood which takes (R, C) as the center, w is the width and h is h, wherein w and h are both odd numbers, sorting the gray level values of pixel points in the neighborhood, and then taking the median as the gray level value at the position of the output image (R, C);

6) obtaining a binary image of the two-dimensional gray level image according to the set defect depth, specifically according to the formula

7) processing the binary image by using morphology, and detecting a connected domain to obtain a binary imageThe image corresponding defect information, specifically, the morphological processing method comprises corrosion, expansion, opening operation and closing operation, wherein the corrosion and expansion need to select an image structural element with a specific size, during corrosion, the structural element is moved from left to right in the image, and the minimum value in the structural element is selected as the value of a pixel point corresponding to an output image; during expansion, the maximum value in the structural elements is selected as the value of a pixel point corresponding to an output image, the process of corrosion first and then expansion is open operation, the process of expansion first and then corrosion is closed operation, and for a binary image, the open operation is firstly carried out by using the square structural elements of 3 by 3, so that a fine area with higher brightness is eliminated, and an object is separated at a fine point; and then, performing closed operation by using a 5-by-5 square structural element to fill fine black holes in the white object and connect adjacent objects, wherein when detecting the connected domain, if the values of eight neighborhood pixels on a certain pixel in the binary image, namely the upper, lower, left, right, upper left, upper right, lower left and lower right pixel are white as same as the pixel, calculating the connected domain, numbering all the detected connected domains in the binary image, outputting the upper left pixel position (top, left), width, height and Area of the corresponding Area of each connected domain, and according to the formula of Area X, determining the Area of the connected domain_RES*Y_RESThe real Area of the defect, Area, can be obtained according to the formula Length Y_RESThe true Length of the defect, Y, can be obtained_RESRepresenting the resolution of the camera in the Y-axis direction;

8) filtering the defects according to the information such as the Area, the length, the standard deviation and the like, reporting the defects meeting the conditions, and specifically, for the set minimum detection Area and the set maximum defect length, the formula Area can be set as Area X_RES*Y_RESAnd the formula Length Y_RESThe calculation result of (2) is used for filtering the defect which does not meet the requirement, and the pixel points in the defect area can be calculated according to the formula

Technical Field

The invention relates to the technical field of steel pipe detection, in particular to a nondestructive detection device for detecting three-dimensional defects on the surface of a seamless steel pipe.

Background

When the hot-rolled steel pipe passes through the cooling bed, a small amount of residual iron oxide scales still exist on the surface of the hot-rolled steel pipe, and the iron oxide scales bring much interference to surface detection. Therefore, in most cases, manual surface inspection is required after the inspection by ultrasonic, magnetic flux leakage or eddy current equipment. The manual surface inspection mainly aims at eliminating machine missing reports, mainly takes pits as a main part, is added with a small amount of outward bending, mainly comprises three categories of pits, outward bending and cracks for the defects of the outer surface, commonly used magnetic leakage, ultrasound and eddy mainly aim at the outward bending, the cracks and the large pits, and the missing reports are easy to occur for the small pits.

Disclosure of Invention

The invention aims to provide a nondestructive testing device for detecting three-dimensional defects on the surface of a seamless steel pipe, which can greatly reduce the missing report of the existing equipment such as ultrasound, magnetic flux leakage, eddy current and the like on a small pit, solve the problem of online automatic detection of the three-dimensional defects on the outer surface of the seamless steel pipe and solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: including device body, automatically controlled and spout mark system, industrial computer and display part, its characterized in that: the device body comprises a body mounting base, a three-dimensional sensor mounting base plate up-and-down motion motor, a three-dimensional sensor and a laser shading shell, the electronic control and spray marking system comprises a pipe photoelectric trigger switch, an encoder, an electronic control cabinet, a nozzle and a coating bottle, a three-dimensional sensor up-and-down motion motor controller, a PLC, a four-way three-dimensional sensor trigger controller and a switching power supply are arranged in the electronic control cabinet, and the industrial computer and the display part comprise an industrial computer and a display mouse keyboard. The device body is provided with four three-dimensional sensors which are arranged on the device body and are vertical to the directions of 45 degrees, 135 degrees, 225 degrees and 315 degrees of the advancing direction of the tube.

Preferably, the nondestructive testing device for the three-dimensional defects on the surface of the seamless steel pipe is specifically operated as follows: when a steel pipe passes through the device body, the incoming pipe photoelectric trigger switch triggers a detection starting signal, the rotary encoder arranged on the roller way triggers the four-way three-dimensional sensor through the trigger controller to simultaneously start to collect the profile data of the surface of the steel pipe, the obtained profile data is transmitted to the industrial personal computer, the profile data is analyzed through a nondestructive detection method, the defects and the positions of the profile data are extracted and fed back to the PLC, and the PLC controls the spray marking system to spray marks. A

Preferably, after the device body detects the defect, the PLC is controlled to jet ink by the nozzle, and the relative distance between the ink jetting position and the defect position is accurately controlled to be not more than 10 cm by adjusting the delay time of the ink jetting.

Preferably, the nondestructive testing method comprises the following steps:

1) generating an initial two-dimensional image according to the formula pipe diameter, specifically, generating an initial two-dimensional image by using the formula W (2 pi) R/X_RESCalculation, where R denotes the pipe radius of the formulation, X_RESThe resolution of the camera in the X-axis direction is represented, the height of the image is determined by the number of lines of the contour line of the tube body output by the camera, and the color of the image is initialized to be black;

2) fitting the ellipse by using least square method to each line of pipe body outline according to the input point cloud data to obtain the center, major axis, minor axis and inclination angle of the ellipse, specifically, setting the ellipse equation of any position of the plane as formula x²+Axy+By²+ Cx + Dy + E equals 0, if N (N ≧ 5) measurement points (x) on the ellipse profile are known_i,y_i) (i-1, 2, …, N), based on the principle of least squares, using the formula

Can find the formula x²+Axy+By²The values of five unknown parameters A, B, C, D, E of + Cx + Dy + E ═ 0 according to the formula

Can calculate the coordinates (x) of the center of the ellipse₀,y₀) Major axis a, minor axis b and tilt angle θ;

3) using the fitted ellipse information, outliers are removed, specifically for each point (x) on the contour₁,y₁) According to the formula

Calculating it to the center of the ellipse (x)₀,y₀) The Euclidean distances are used as a group of samples according to the formula

Calculating the standard deviation, wherein stdev represents the standard deviation of the samples, n represents the number of the samples, and rho_iFor the ith euclidean distance sample value,

is the sample mean. Filtering points with Euclidean distance more than three times of standard deviation as outliers;

4) projecting the data from which the outliers are removed to obtain a two-dimensional gray image, specifically, according to the formula

Calculate each point (x) on the contour₁,y₁) To the center of the ellipse (x)₀,y₀) According to the formula

Calculating the theoretical Euclidean distance r from the point to the center of the ellipse, wherein s is represented by the formula s ═ y₁-y₀)cosθ-(x₁-x₀) sin theta)/rho are calculated according to the formula

Calculating pixel values pixel corresponding to the two-dimensional gray image, wherein Z_RESIs the resolution of the camera in the Z-axis direction, pixelMid is the median of the image pixel range, so if there is no fluctuation, the corresponding pixel value pixel is the median; if the point is a depressed point, pixel is below the median; if the dot is a convex dot, pixel is above the median;

5) performing median filtering on the gray level image, specifically, the median filtering can remove salt and pepper noise in the image, assuming that the height of the input image is R and the width is C, for any position (R, C) in the image, R is more than or equal to 0 and less than R, C is more than or equal to 0 and less than C, taking a neighborhood which takes (R, C) as the center, w is the width and h is h, wherein w and h are both odd numbers, sorting the gray level values of pixel points in the neighborhood, and then taking the median as the gray level value at the position of the output image (R, C);

6) obtaining a binary image of the two-dimensional gray level image according to the set defect depth, specifically according to the formula

The input defect depth set value Z can be calculated_inputThreshold value Z of corresponding two-dimensional gray scale image_pixelChecking the corresponding pixel value of the gray image, for values less than Z_pixelAnd greater than Z_pixelSetting the corresponding pixel value of the binary image to be white, otherwise, setting the corresponding pixel value to be black, and obtaining the final binary image;

7) the method comprises the steps of processing a binary image by using morphology, and detecting a connected domain to obtain defect information corresponding to the binary image, wherein the morphology processing method specifically comprises corrosion, expansion, opening operation and closing operation, an image structural element with a specific size is required to be selected for corrosion and expansion, the structural element is moved from left to right in the image during corrosion, and the minimum value in the structural element is selected as the value of a pixel point corresponding to an output image; during expansion, the maximum value in the structural elements is selected as the value of a pixel point corresponding to an output image, the process of corrosion first and then expansion is open operation, the process of expansion first and then corrosion is closed operation, and for a binary image, the open operation is firstly carried out by using the square structural elements of 3 by 3, so that a fine area with higher brightness is eliminated, and an object is separated at a fine point; and then, performing closed operation by using a 5-by-5 square structural element to fill fine black holes in the white object and connect adjacent objects, wherein when detecting the connected domain, if the values of eight neighborhood pixels on a certain pixel in the binary image, namely the upper, lower, left, right, upper left, upper right, lower left and lower right pixel are white as same as the pixel, calculating the connected domain, numbering all the detected connected domains in the binary image, outputting the upper left pixel position (top, left), width, height and Area of the corresponding Area of each connected domain, and according to the formula of Area X, determining the Area of the connected domain_RES*Y_RESThe real Area of the defect, Area, can be obtained according to the formula Length Y_RESThe true Length of the defect, Y, can be obtained_RESRepresenting the resolution of the camera in the Y-axis direction;

8) filtering the defects according to the information such as the Area, the length, the standard deviation and the like, reporting the defects meeting the conditions, and specifically, for the set minimum detection Area and the set maximum defect length, the formula Area can be set as Area X_RES*Y_RESAnd the formula Length Y_RESFiltering the defect which does not meet the requirement according to the calculation result of (1). The pixel points in the defect area can be classified according to the formula

And calculating the standard deviation of the pixel values, and filtering the defects which do not meet the standard deviation requirement.

Compared with the prior art, the invention has the beneficial effects that: the device is used for repeatedly running the sample pipe, the nicking injuries are completely reported, the device meets the requirements of users and 5% of wall thickness of API, after the device is used, the missing report of the existing devices such as ultrasound, magnetic leakage and eddy current to a small pit can be greatly reduced, and the problem of online automatic detection of three-dimensional defects of the outer surface of the seamless steel pipe is solved.

Drawings

FIG. 1 is a schematic view of the overall structure of a nondestructive testing device for detecting three-dimensional defects on the surface of a seamless steel pipe according to the present invention;

FIG. 2 is a schematic view of a layout of a three-dimensional sensor of a nondestructive testing device for detecting three-dimensional defects on the surface of a seamless steel pipe according to the present invention;

FIG. 3 is a flow chart of point cloud data processing of the nondestructive testing device for detecting three-dimensional defects on the surface of a seamless steel pipe.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides a technical solution:

the utility model provides a nondestructive test device for three-dimensional defect detection in seamless steel pipe surface, includes device body, automatically controlled and spouts mark system, industrial computer and display part, its characterized in that: the device body comprises a body mounting base, a three-dimensional sensor mounting base plate up-and-down motion motor, a three-dimensional sensor and a laser shading shell, an electronic control and spray marking system comprises a pipe photoelectric trigger switch, an encoder, an electronic control cabinet, a nozzle and a coating bottle, a three-dimensional sensor up-and-down motion motor controller, a PLC, a four-way three-dimensional sensor trigger controller and a switch power supply are arranged in the electronic control cabinet, and the industrial computer and a display part comprise an industrial computer and a display mouse keyboard.

The device body is provided with four three-dimensional sensors which are arranged on the device body and are vertical to the directions of 45 degrees, 135 degrees, 225 degrees and 315 degrees of the advancing direction of the tube.

The nondestructive testing device for the three-dimensional defects on the surface of the seamless steel pipe is specifically operated as follows: when the steel pipe passes through the device body, the incoming pipe photoelectric trigger switch triggers a detection signal, the rotary encoder installed on the roller way triggers the four-way three-dimensional sensor through the trigger controller to simultaneously start to collect the profile data of the surface of the steel pipe, the obtained profile data is transmitted to the industrial personal computer, the profile data is analyzed through a nondestructive detection method, the defects and the positions of the profile data are extracted and fed back to the PLC, and the PLC controls the mark spraying system to spray marks. A

The device body controls the nozzle to jet ink after detecting the defect by controlling the PLC, and the relative distance between the ink jet position and the defect position is accurately controlled to be not more than 10 cm by adjusting the ink jet delay time.

The nondestructive testing method comprises the following steps:

1) generating an initial two-dimensional image according to the formula pipe diameter, specifically, generating an initial two-dimensional image by using the formula W (2 pi) R/X_RESCalculation, where R denotes the pipe radius of the formulation, X_RESThe resolution of the camera in the X-axis direction is represented, the height of the image is determined by the number of lines of the contour line of the tube body output by the camera, and the color of the image is initialized to be black;

2) fitting the ellipse by using least square method to each line of pipe body outline according to the input point cloud data to obtain the center, major axis, minor axis and inclination angle of the ellipse, specifically, setting the ellipse equation of any position of the plane as formula x²+Axy+By²+ Cx + Dy + E equals 0, if N (N ≧ 5) measurement points (x) on the ellipse profile are known_i,y_i)(i 1,2, …, N), then by the principle of least squares, the equation

Can find the formula x²+Axy+By²The values of five unknown parameters A, B, C, D, E of + Cx + Dy + E ═ 0 according to the formula

Can calculate the coordinates (x) of the center of the ellipse₀,y₀) Major axis a, minor axis b and tilt angle θ;

3) using the fitted ellipse information, outliers are removed, specifically for each point (x) on the contour₁,y₁) According to the formula

Calculating it to the center of the ellipse (x)₀,y₀) The Euclidean distances are used as a group of samples according to the formula

Calculating the standard deviation, wherein stdev represents the standard deviation of the samples, n represents the number of the samples, and rho_iFor the ith euclidean distance sample value,is the sample mean. Filtering points with Euclidean distance more than three times of standard deviation as outliers;

4) projecting the data from which the outliers are removed to obtain a two-dimensional gray image, specifically, according to the formula

Calculate each point (x) on the contour₁,y₁) To the center of the ellipse (x)₀,y₀) According to the formula

Calculating the theoretical Euclidean distance r from the point to the center of the ellipse, wherein s is represented by the formula s ═ y₁-y₀)cosθ-(x₁-x₀) sin theta)/rho are calculated according to the formula

Calculating pixel values pixel corresponding to the two-dimensional gray image, wherein Z_RESIs the resolution of the camera in the Z-axis direction, pixelMid is the median of the image pixel range, so if there is no fluctuation, the corresponding pixel value pixel is the median; if the point is a depressed point, pixel is below the median; if the dot is a convex dot, pixel is above the median;

5) performing median filtering on the gray level image, specifically, the median filtering can remove salt and pepper noise in the image, assuming that the height of the input image is R and the width is C, for any position (R, C) in the image, R is more than or equal to 0 and less than R, C is more than or equal to 0 and less than C, taking a neighborhood which takes (R, C) as the center, w is the width and h is h, wherein w and h are both odd numbers, sorting the gray level values of pixel points in the neighborhood, and then taking the median as the gray level value at the position of the output image (R, C);

6) obtaining a binary image of the two-dimensional gray level image according to the set defect depth, specifically according to the formula

The input defect depth set value Z can be calculated_inputThreshold value Z of corresponding two-dimensional gray scale image_pixelChecking the corresponding pixel value of the gray image, for values less than Z_pixelAnd greater than Z_pixelSetting the corresponding pixel value of the binary image to be white, otherwise, setting the corresponding pixel value to be black, and obtaining the final binary image;

7) the method comprises the steps of processing a binary image by using morphology, and detecting a connected domain to obtain defect information corresponding to the binary image, wherein the morphology processing method specifically comprises corrosion, expansion, opening operation and closing operation, an image structural element with a specific size is required to be selected for corrosion and expansion, the structural element is moved from left to right in the image during corrosion, and the minimum value in the structural element is selected as the value of a pixel point corresponding to an output image; on expansion, as opposed to corrosion, in selected structural elementsThe maximum value of the binary image is used as the value of a pixel point corresponding to the output image, the process of corrosion first and then expansion is open operation, the process of expansion first and then corrosion is closed operation, and for the binary image, the open operation is firstly carried out by using a 3-by-3 square structural element, so that a fine area with higher brightness is eliminated, and an object is separated at a fine point; and then, performing closed operation by using a 5-by-5 square structural element to fill fine black holes in the white object and connect adjacent objects, wherein when detecting the connected domain, if the values of eight neighborhood pixels on a certain pixel in the binary image, namely the upper, lower, left, right, upper left, upper right, lower left and lower right pixel are white as same as the pixel, calculating the connected domain, numbering all the detected connected domains in the binary image, outputting the upper left pixel position (top, left), width, height and Area of the corresponding Area of each connected domain, and according to the formula of Area X, determining the Area of the connected domain_RES*Y_RESThe real Area of the defect, Area, can be obtained according to the formula Length Y_RESThe true Length of the defect, Y, can be obtained_RESRepresenting the resolution of the camera in the Y-axis direction;

8) filtering the defects according to the information such as the Area, the length, the standard deviation and the like, reporting the defects meeting the conditions, and specifically, for the set minimum detection Area and the set maximum defect length, the formula Area can be set as Area X_RES*Y_RESAnd the formula Length Y_RESFiltering the defect which does not meet the requirement according to the calculation result of (1). The pixel points in the defect area can be classified according to the formula

And calculating the standard deviation of the pixel values, and filtering the defects which do not meet the standard deviation requirement.

To better verify the feasibility of the device, the following experiments were performed:

a three-dimensional laser sensor of a type of a gotacor 2340 manufactured by lmi is selected to measure the diameter range of the steel pipe from 114 to 254mm, wherein the sensor layout (shown in figure 2) is distributed in directions of 45 degrees, 135 degrees, 225 degrees and 315 degrees from the center XXmm, so that the 360-degree outer surface of the pipe body can be completely measured from 114mm to 254 mm. The encoder is installed on a roller line, signals of the encoder are connected to a Master 810 controller of lmi company, and four controllers 2340 are controlled to collect signals at the same time. Each encoder pulse triggers contour line acquisition once, contour lines are spliced into a finished circular arc through self-developed software, and ellipse fitting is carried out on the circular arc.

Adopt the stainless steel base plate to be used for fixed gotcator 2340, its up-and-down motion is controlled through linear electric motor to the base plate, chooses siemens PLC to be used for receiving photoelectric switch signal for use, adopts the institute hua industrial computer as the control host computer.

Finally, the equipment passes strict acceptance requirements, and the specific acceptance process is as follows: three groups of circular scratches with the diameter of 5.7mm and the depth of 0.38mm are processed on a sample tube with the wall thickness of 7.72mm of 139.7 mm by using a spark scratch instrument, the radial angle difference of each group of scratches is 120 degrees, the device is used for repeatedly operating the sample tube for 20 times, and the scratches are all reported, so that the device meets the requirements of users and 5% of the wall thickness of API.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.