CN115121927B - Real-time centering and correcting method for pipe for electromagnetic pulse welding - Google Patents

Abstract

The invention relates to a device and method for real-time centering and deviation correction of pipes for electromagnetic pulse welding. The device includes an electromagnetic pulse welding station, a pipe centering and deviation correction module, and an image acquisition and processing module. An outer pipe is installed on the electromagnetic pulse welding station. The pipe centering and deviation correction module includes a cross slide mechanism and a controller. The inner pipe is installed on the cross slide mechanism. The image acquisition and processing module is used to obtain the assembly image of the inner and outer pipes, process the image and calculate the eccentricity of the inner and outer pipes. If the eccentricity meets the welding requirements, the inner and outer tubes are welded by an electromagnetic pulse welding station. If the eccentricity does not meet the welding requirements, the controller controls the cross slide mechanism to drive the inner tube to move horizontally and vertically, and then adjust the inner and outer tubes. Eccentricity, to achieve centering correction of inner and outer tubes. The device and method are beneficial to improving the centering efficiency and accuracy of inner and outer pipes in electromagnetic pulse welding of pipes with different diameters.

Description

A method for real-time centering and deviation correction of pipes for electromagnetic pulse welding

technical field

The invention belongs to the field of welding technology, in particular to a device and method for real-time centering and deviation correction of pipes for electromagnetic pulse welding.

Background technique

Electromagnetic pulse technology is based on the principle of electromagnetic induction. Through instantaneous discharge, an induced magnetic field in the opposite direction is generated on the surface of the induction coil and the highly conductive outer tube. Under the action of electromagnetic repulsion, the outer tube collides with the inner tube at high speed to form a welded joint. This method can effectively improve the butt joint efficiency of pipes with different inner diameters.

However, during the welding process, whether the inner and outer tubes are centered or not, that is, the size of the eccentricity will determine whether the force on the inner tube and the combination of the inner and outer tubes are uniform. The traditional centering method mostly adopts manual control of the cross-step slide table for centering, which has low efficiency and poor precision, which has become a bottleneck problem restricting further efficiency improvement.

Contents of the invention

The object of the present invention is to provide a real-time centering and deviation correction device and method for pipes for electromagnetic pulse welding, which are beneficial to improving the efficiency and accuracy of centering inner and outer pipes in electromagnetic pulse welding of pipes with different diameters.

In order to achieve the above object, the technical solution adopted by the present invention is: a real-time centering and deviation correction device for electromagnetic pulse welding pipes, including an electromagnetic pulse welding station, a pipe centering and deviation correction module, and an image acquisition and processing module. The outer pipe is installed, the pipe centering and deviation correction module includes a cross slide mechanism and a controller, the inner pipe is installed on the cross slide mechanism, and the image acquisition and processing module is used to obtain the assembly image of the inner and outer pipes, process the image and Calculate the eccentricity of the inner and outer tubes. If the eccentricity meets the welding requirements, the inner and outer tubes will be welded by an electromagnetic pulse welding station. If the eccentricity does not meet the welding requirements, the controller will control the cross slide mechanism to drive the inner tube to perform horizontal and vertical welding. Move, and then adjust the eccentricity of the inner and outer tubes, and realize the centering and deviation correction of the inner and outer tubes.

Further, the image acquisition and processing module includes an industrial camera and a computer. The industrial camera captures an assembly image of the inner and outer tubes and then transmits it to the computer. The computer processes the image based on an image processing algorithm to obtain the outline of the inner and outer tubes in the image and The center of the circle, and then calculate the eccentricity of the inner and outer tubes.

Further, the image processing algorithm is a Hough circle detection algorithm.

Further, the computer judges whether the eccentricity meets the welding requirements according to the calculated eccentricity of the inner and outer pipes, and if so, sends a welding instruction to the electromagnetic pulse welding station, and welds the inner and outer pipes through the electromagnetic pulse welding station; otherwise, sends a deviation correction instruction and The eccentricity data is used to correct the deviation of the controller. According to the eccentricity data, the controller calculates the horizontal and vertical distances that the inner tube needs to move respectively, and then controls the cross slide mechanism to drive the inner tube to move the corresponding distance horizontally and vertically. , and then realize the adjustment of the eccentricity of the inner and outer tubes; the image acquisition and processing module continues to acquire and process the assembly images of the inner and outer tubes and calculate the eccentricity of the inner and outer tubes until the eccentricity meets the requirements.

Further, the controller is an Arduino microcontroller.

The present invention also provides a method for real-time centering and deviation correction of pipes for electromagnetic pulse welding based on the above-mentioned device, comprising the following steps:

Step 1. The industrial camera on the image acquisition and processing module acquires the assembly image of the inner and outer pipes, and sends it to the computer on the image acquisition and processing module;

Step 2. The computer obtains the image taken by the industrial camera, and converts the non-grayscale image into a grayscale image;

Step 3. Through a series of processing including binarization, median filtering, and Gaussian blurring, the tiny contours are filtered to make the edges of objects in the image clearer:

Among them, C is the perimeter of profile i, n is the number of profiles, AVG is the mean value of profile length, and profile _i (x, y) is the image of profile i;

Step 4. Calculate the x-direction derivative and the y-direction derivative for each non-zero point (i, j) on the edge image processed in step 3 by edge detection, thereby obtaining the gradient; from the edge point, along the inverse of the gradient and the gradient Direction, adjust the estimated maximum and minimum radius, each pixel from the estimated minimum radius r _min to the maximum radius r _max specified by the parameters of the Hough circle detection algorithm is accumulated in the accumulator; at the same time, record each non- 0 pixel position;

Among them, I is the value of the pixel in the image, and (i, j) is the coordinate of the pixel;

Step 5. Select candidate centers from the points in the accumulator, the values of the candidate centers are greater than the set threshold and greater than the accumulated values of its four adjacent neighbor points; the candidate centers are arranged in descending order according to the accumulated values;

Step 6. For each candidate center, consider all non-zero pixels in the edge image, these non-zero pixels are sorted according to their distance from the candidate center, and select a radius most supported by non-zero pixels;

Step 7. If a candidate center is fully supported by all non-zero pixels in the edge image and has a sufficient distance to the candidate center selected in the previous stage, the candidate center is retained;

Step 8. Output the retained center and the radius of the corresponding circle;

Step 9. Calculate the eccentricity of the inner and outer pipes;

Step 10. If the eccentricity meets the welding requirements, use the electromagnetic pulse welding station to weld the inner and outer pipes. If the eccentricity does not meet the welding requirements, use the pipe centering correction module to drive the inner pipe to move horizontally and vertically, and then adjust the inner and outer pipes. Tube eccentricity to realize centering and correction of inner and outer tubes.

Further, in the step 2, the image type is judged to determine whether to convert it into a grayscale image, if it is not a grayscale image, it is converted into a grayscale image, and its calculation method is:

Among them, R, G, and B represent the colors of the three channels of red, green, and blue, respectively.

Compared with the prior art, the present invention has the following beneficial effects: It provides a device and method for automatically centering and correcting the inner and outer pipes during the electromagnetic pulse welding process of pipes with different diameters. The shortcomings of low efficiency and inaccuracy in centering, high centering efficiency and precision, and thus improve the practicability of the centering deviation correction system, expand its scope of application, and have broad application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the embodiment of the present invention.

Fig. 2 is a schematic diagram of the image acquisition and processing process in the embodiment of the present invention.

In the figure: 1. Electromagnetic pulse welding station; 2. Cross slide mechanism; 3. Controller; 4. Industrial camera; 5. Computer; 6. Outer tube; 7. Inner tube; 8. Driver.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

As shown in Figure 1, this embodiment provides a real-time centering and deviation correction device for electromagnetic pulse welding pipes, including an electromagnetic pulse welding station 1, a pipe centering and deviation correction module, and an image acquisition and processing module. The outer pipe 6 is installed, and the pipe centering and deviation correction module includes a cross slide mechanism 2 and a controller 3, and an inner pipe 7 is installed on the cross slide mechanism 2, and the image acquisition and processing module is used to obtain an assembly image of the inner and outer pipes, Process the image and calculate the eccentricity of the inner and outer tubes. If the eccentricity meets the welding requirements, the inner and outer tubes are welded by the electromagnetic pulse welding station 1. If the eccentricity does not meet the welding requirements, the cross slide mechanism 2 is controlled by the controller 3 Drive the inner tube to move horizontally and vertically, and then adjust the eccentricity of the inner and outer tubes to achieve centering and deviation correction of the inner and outer tubes.

In this embodiment, the inner tube 7 is a stainless steel tube, and the outer tube 6 is a pure aluminum tube or an aluminum alloy tube.

In this embodiment, the controller 3 is an Arduino microcontroller. The image acquisition and processing module includes an industrial camera 4 and a computer 5. The industrial camera 4 captures an assembly image of the inner and outer pipes, and then transmits it to the computer 5. The computer 5 processes the image based on an image processing algorithm, and obtains the image of the inner and outer pipes in the image. Outline and center, and then calculate the eccentricity of the inner and outer tubes. In this embodiment, the image processing algorithm uses the OpenCV+Python Hough circle detection algorithm.

The computer 5 judges whether the eccentricity meets the welding requirements according to the calculated eccentricity of the inner and outer pipes, and if so, sends a welding instruction to the electromagnetic pulse welding station 1, and welds the inner and outer pipes through the electromagnetic pulse welding station 1; otherwise, sends a deviation correction instruction and The eccentricity data is sent to the controller 3 for deviation correction operation, and the controller 3 calculates the distances that the inner tube needs to move in the horizontal and vertical directions according to the eccentricity data, and then controls the cross slide mechanism 2 to drive the inner tube to move the corresponding distance horizontally and vertically. Move vertically, and then realize the adjustment of the eccentricity of the inner and outer tubes; the image acquisition and processing module continues to acquire and process the assembly images of the inner and outer tubes and calculate the eccentricity of the inner and outer tubes until the eccentricity meets the requirements.

This embodiment also provides a method for real-time centering and deviation correction of pipes for electromagnetic pulse welding based on the above-mentioned device, including the following steps:

Step 1. The industrial camera on the image acquisition and processing module acquires the assembly image of the inner and outer tubes, and sends it to the computer on the image acquisition and processing module. The acquired image and the image during subsequent processing are shown in Figure 2.

Step 2. The computer obtains the image taken by the industrial camera, and then judges the image type to determine whether to convert it into a grayscale image. If it is not a grayscale image, convert it into a grayscale image. The calculation method is:

Among them, R, G, and B represent the colors of the three channels of red, green, and blue, respectively.

Step 3. Through a series of processing including binarization, median filtering, and Gaussian blurring, the tiny contours are filtered to make the edges of objects in the image clearer;

Among them, C is the perimeter of profile i, n is the number of profiles, AVG is the average length of profile, and profile _i (x, y) is the image of profile i.

Step 4. Calculate the x-direction derivative and the y-direction derivative for each non-zero point (i, j) on the edge image processed in step 3 by edge detection, thereby obtaining the gradient; from the edge point, along the inverse of the gradient and the gradient Direction, adjust the estimated maximum and minimum radius, each pixel from the estimated minimum radius r _min to the maximum radius r _max specified by the parameters of the Hough circle detection algorithm is accumulated in the accumulator; at the same time, record each non- 0 pixel position;

Among them, I is the value of the pixel in the image (such as: RGB value), and (i, j) is the coordinate of the pixel.

Step 5. Select candidate centers from the points in the accumulator, the values of the candidate centers are all greater than the set threshold and greater than the accumulated values of its four adjacent neighbor points; the candidate centers are arranged in descending order according to the accumulated values, so that The center of the most supported pixel comes first.

Step 6. For each candidate center, consider all non-zero pixels in the edge image, and these non-zero pixels are sorted according to their distance from the candidate center; from the largest radius to the smallest distance, select the most supported radius of non-zero pixels .

Step 7. If a candidate center is fully supported by all non-zero pixels in the edge image, and has a sufficient distance to the candidate center selected in the previous stage (ie, greater than the set distance), the candidate center is retained.

In this way, the non-zero element verification of the edge image and the distance verification of the candidate center are realized for the candidate center.

Step 8. Output the center of the reserved circle (ie the center) and the radius of the corresponding circle.

Step 9. Calculate the eccentricity of the inner and outer tubes.

The radius of the best circle is obtained when the accumulator estimates the maximum and minimum radii. The obtained eccentricity calculated by the center of the circle is the pixel eccentricity, which can be verified in combination with the actual distance in the real space. If the outer tube is 48mm, the actual eccentricity can be measured as l, and the eccentricity calculated by the computer is assumed to be d, d/l=r (outer tube)/48.

Step 10. If the eccentricity meets the welding requirements, use the electromagnetic pulse welding station to weld the inner and outer pipes. If the eccentricity does not meet the welding requirements, use the pipe centering correction module to drive the inner pipe to move horizontally and vertically, and then adjust the inner and outer pipes. Tube eccentricity to realize centering and correction of inner and outer tubes.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this profession may use the technical content disclosed above to change or modify the equivalent of equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (4)

1. The method is characterized in that the method is realized based on a real-time centering and rectifying device for the electromagnetic pulse welding pipe, the real-time centering and rectifying device for the electromagnetic pulse welding pipe comprises an electromagnetic pulse welding table, a pipe centering and rectifying module and an image acquisition and processing module, an outer pipe is arranged on the electromagnetic pulse welding table, the pipe centering and rectifying module comprises a cross sliding table mechanism and a controller, an inner pipe is arranged on the cross sliding table mechanism, the image acquisition and processing module is used for acquiring an assembly image of the inner pipe and the outer pipe, processing the image and calculating the eccentricity of the inner pipe and the outer pipe, if the eccentricity meets the welding requirement, the inner pipe and the outer pipe are welded through the electromagnetic pulse welding table, if the eccentricity does not meet the welding requirement, the inner pipe is driven to transversely and vertically move through the cross sliding table mechanism under the control of the controller, and the eccentricity of the inner pipe and the outer pipe is adjusted, so that the centering and rectifying of the inner pipe and the outer pipe are realized; the image acquisition processing module comprises an industrial camera and a computer, wherein the industrial camera shoots an inner tube and outer tube assembly image and then transmits the inner tube and outer tube assembly image to the computer, and the computer processes the image based on an image processing algorithm to acquire the outline and the circle center of the inner tube and the outer tube in the image so as to calculate the eccentric distance of the inner tube and the outer tube; the image processing algorithm is a Hough circle detection algorithm;

the method comprises the following steps:

step 1, an industrial camera on an image acquisition and processing module acquires assembly images of an inner tube and an outer tube and sends the assembly images to a computer on the image acquisition and processing module;

step 2, the computer acquires an image shot by the industrial camera and converts the non-gray level image into a gray level image;

and 3, filtering the micro contour through a series of processes including binarization, median filtering and Gaussian blur, so that the edges of objects in the image are clearer:

wherein C is the perimeter of the contour i, n is the number of contours, AVG is the average value of the contour length, and contour _i (xY) is an image of contour i;

step 4, calculating the derivative in the x direction and the derivative in the y direction of each non-zero point (i, j) on the edge image processed in the step 3 through edge detection, so as to obtain a gradient; from the edge points, along the gradient and the opposite direction of the gradient, the estimated maximum and minimum radius is adjusted, and the estimated minimum radius r specified by the parameters of the Hough circle detection algorithm is adjusted _min To a maximum radius r _max Is accumulated in an accumulator; simultaneously recording the position of each non-0 pixel in the edge image;

wherein I is the value of a pixel in the image and (I, j) is the coordinates of the pixel;

step 5, selecting candidate centers from points in the accumulator, wherein the values of the candidate centers are all larger than a set threshold value and larger than the accumulated values of four adjacent neighborhood points; the candidate centers are arranged in descending order of accumulated value;

step 6, considering all non-0 pixels in the edge image for each candidate center, sorting the non-0 pixels according to the distance between the non-0 pixels and the candidate center, and selecting a radius which is most supported by the non-0 pixels;

step 7, if one candidate center is supported by all non-0 pixels in the edge image fully and has a sufficient distance to the candidate center selected in the earlier stage, the candidate center is reserved;

step 8, outputting the reserved center and the radius of the corresponding circle;

step 9, calculating to obtain the eccentricity of the inner tube and the outer tube;

and 10, welding the inner tube and the outer tube through an electromagnetic pulse welding table if the eccentricity meets the welding requirement, and driving the inner tube to transversely and vertically move through a tube centering deviation correcting module if the eccentricity does not meet the welding requirement, so as to adjust the eccentricity of the inner tube and the outer tube, and realize centering deviation correcting of the inner tube and the outer tube.

2. The method for centering and correcting the pipe for electromagnetic pulse welding in real time according to claim 1, wherein the computer judges whether the eccentricity meets the welding requirement according to the calculated eccentricity of the inner pipe and the outer pipe, if so, the computer sends a welding instruction to an electromagnetic pulse welding table, and the inner pipe and the outer pipe are welded through the electromagnetic pulse welding table; otherwise, sending a deviation rectifying instruction and eccentricity data to a controller for deviation rectifying operation, calculating the distances required to move respectively in the transverse direction and the vertical direction of the inner tube according to the eccentricity data by the controller, and then controlling a cross sliding table mechanism to drive the inner tube to move in the transverse direction and the vertical direction of the corresponding distances, so that the eccentricity adjustment of the inner tube and the outer tube is realized; and the image acquisition and processing module continues to acquire and process the inner and outer tube assembly images and calculate the eccentricity of the inner and outer tubes until the eccentricity meets the requirement.

3. The method for centering and correcting the pipe for electromagnetic pulse welding in real time according to claim 1, wherein the controller is an Arduino single-chip microcomputer.

4. The method for real-time centering and correcting a pipe for electromagnetic pulse welding according to claim 1, wherein in the step 2, the image type is judged to determine whether to convert into a gray scale map, if not, the image type is converted into a gray scale map, and the calculation method is as follows:

wherein R, G, B represents the colors of the three channels red, green and blue, respectively.

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