Welding quality detection method and detection system

Abstract

The invention relates to the technical field of welding quality detection, and provides a welding quality detection method and system, and the method comprises the following steps: arranging a plurality of welding strips in parallel, and enabling the welding strips to be welded; the welding quality detection device is located above the welding strip, the welding quality detection device or the welding strip moves horizontally, and the moving direction is perpendicular to the length direction of the welding strip; the line laser transmitter transmits line laser to the multiple welding strips, so that the absolute value of the included angle between the line laser and the length direction of the welding strips is 5-85 degrees; the welding quality detection device or the welding strip continuously moves, and the camera continuously shoots the line laser to obtain a plurality of shot images; according to the plurality of shot images, dotted contours of the plurality of solder strips are calculated; and the welding quality is judged according to the point-shaped contours of the multiple welding strips. According to the scheme, more scanning points can be obtained, and calculation errors caused by macroscopic jitter of the moving object under the actual production condition can be reduced, so that higher detection precision is obtained, and the real welding quality is judged.

Description

Technical Field

[0001] The present invention relates to the technical field of welding quality detection, and in particular to a welding quality detection method and detection system. Background Art

[0002] In the production process of solar cell modules, multiple parallel solder strips are usually soldered to the cell, such as Figure 1 and 2 As shown in the figure, a series of problems may occur after welding. The thin line above each picture represents the welding ribbon, and the thick line below represents the bus bar. The right side of the welding ribbon is connected to the solar cell. Figure 1 a means the solder strip is missing. Figure 1 b: The welding strip is too long. Figure 1 c: The welding strip is too short. Figure 1 d is the strip offset, Figure 2 a is the warping of the front end of the welding strip. Figure 2 b is the warping of the rear end of the welding strip. Figure 2 c is the fishhook-shaped warping of the welding strip, Figure 2 d: The welding strip is not welded.

[0003] After the welding of the welding ribbon and the busbar is completed, it will move along the direction perpendicular to the length of the welding ribbon for more than ten seconds before entering the next process. The effective detection time is less than 2 seconds, so the time to detect whether the welding ribbon is welded is very short. If horizontal scanning is used, the laser 3D line scan camera will move along the length of the welding ribbon to scan the welding ribbon, which will waste a lot of time and cannot be fully detected within more than ten seconds. Figure 3 As shown, the prior art generally allows the laser 3D line scan camera and the solder strip to move relative to each other in a direction perpendicular to the length of the solder strip, with the line laser parallel to the length of the solder strip. Due to the limited frame rate of the camera and the short exposure time, there is a high probability that the complete outline cannot be depicted when photographing defects and object edges, so it is impossible to obtain information on the welding conditions of all solder strips. Figure 3 In the figure, the enlarged image shows the camera taking multiple images and the irradiation position of the line laser. It can be seen that the line laser 4 is parallel to the welding strip 1, and the line laser cannot completely collect the edge information of the welding strip.

[0004] Therefore, it is necessary to provide a welding quality detection method that can obtain more scanning points, thereby obtaining higher detection accuracy and further determining the welding quality.

[0005] The above information disclosed in the Background section is only for enhancement of understanding of the background of the present application and therefore it may contain information that does not constitute the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0006] The main purpose of the present invention is to overcome the problem of low accuracy and efficiency of welding quality detection, and to provide a welding quality detection method that can not only obtain more scanning points, but also reduce the calculation error caused by the macro-jitter of the moving object under actual production conditions, thereby obtaining higher detection accuracy and further judging the actual welding quality.

[0007] To achieve the above-mentioned purpose, the first aspect of the present invention provides a method for detecting welding quality, using a welding quality detection device, the welding quality detection device including a camera and a line laser transmitter, and comprising the following steps:

[0008] A plurality of welding strips are arranged in parallel, and a plurality of welding strips have been welded;

[0009] The welding quality detection device is located above the welding strip, and the welding quality detection device or the welding strip moves horizontally, and the moving direction is perpendicular to the length direction of the welding strip;

[0010] The line laser emitter emits line lasers to the plurality of welding strips, so that the absolute value of the angle between the line laser and the length direction of the welding strip is 5-85 degrees;

[0011] The welding quality inspection device or the welding strip is in continuous motion, and the camera continuously shoots the line laser to obtain multiple images;

[0012] Calculate the dotted contours of multiple welding strips based on multiple captured images;

[0013] The welding quality is judged based on the dotted profiles of multiple welding strips.

[0014] According to an exemplary embodiment of the present invention, the welding quality inspection device uses a 3D line laser scanning camera.

[0015] According to an exemplary embodiment of the present invention, the width of the welding strip is 0.1-2 mm.

[0016] According to an exemplary embodiment of the present invention, the relative movement speed between the welding quality detection device and the welding strip is 0.1-3 m / s.

[0017] According to an exemplary embodiment of the present invention, the shooting frequency of the camera is 1000-5000 Hz.

[0018] Preferably, the shooting frequency of the camera is 3000 Hz.

[0019] As a second aspect of the present invention, a welding quality detection system is provided, wherein the welding quality detection system uses the welding quality detection method to detect welding quality.

[0020] According to an exemplary embodiment of the present invention, the detection system includes a welding quality detection device, a motion device and a resolution device; the welding quality detection device includes a camera and a line laser transmitter;

[0021] A camera and a line laser transmitter are arranged above the welding strip and fixed on a moving device; a plurality of welding strips are arranged in parallel, and a plurality of welding strips have been welded;

[0022] The line laser emitter emits line lasers to the plurality of welding strips, so that the absolute value of the angle between the line laser and the length direction of the welding strip is 5-85 degrees;

[0023] The camera continuously shoots the line laser to obtain multiple images;

[0024] The moving device is used to drive the welding quality detection device or the plurality of welding strips to move horizontally along a direction perpendicular to the length of the welding strips;

[0025] The calculating device is connected to the camera for communication, and is used for calculating the dot profiles of the multiple welding strips according to the captured images; and judging the welding quality according to the dot profiles of the multiple welding strips.

[0026] According to an exemplary embodiment of the present invention, the welding quality inspection device uses a 3D line laser scanning camera.

[0027] The advantages of the present invention are:

[0028] The present invention tilts the line laser so that there is a certain angle between the line laser and the length direction of the welding strip, so that the intersection of the line laser and the welding strip is no longer a point but a line, and more height information can be extracted. On the basis of not increasing the camera frame rate, not only more scanning points can be obtained, but also the calculation error caused by the macroscopic jitter of the moving object under actual production conditions can be reduced, thereby obtaining higher detection accuracy and further judging the actual welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present application will become more apparent by describing in detail the exemplary embodiments thereof with reference to the accompanying drawings. The accompanying drawings described below are only some embodiments of the present application, and it is clear to a person skilled in the art that other accompanying drawings can be obtained from these accompanying drawings without creative effort.

[0030] Figure 1 The schematic diagram schematically shows the defects of the welding strip itself in the prior art.

[0031] Figure 2 The schematic diagram of poor welding of welding strips in the prior art is schematically shown.

[0032] Figure 3 The schematic diagram of welding quality detection in the prior art is schematically shown.

[0033] Figure 4 The schematic diagram of welding quality detection of this scheme is schematically shown.

[0034] Figure 5 The figure schematically shows the weld strip profile calculated after the laser line is arranged parallel to the weld strip in the prior art.

[0035] Figure 6 The schematic diagram shows the weld strip contour calculated when the laser line forms an angle of 5-85 degrees with the weld strip.

[0036] Figure 7 The schematic diagram shows the component shaking shooting effect after the laser line and the welding strip are arranged in parallel in the prior art.

[0037] Figure 8 The schematic diagram shows the jitter shooting effect of the component when the laser line and the welding strip form an angle of 5-85 degrees.

[0038] Fig. 9 The solution effect diagram of this scheme is schematically shown.

[0039] Fig.10 The figure schematically shows the solution effect diagram of the prior art.

[0040] Fig.11 The schematic diagram shows the effect of detecting defects of the welding strip itself by this solution.

[0041] Fig.12 The schematic diagram shows the effect of detecting poor welding of welding strips according to the present solution.

[0042] Among them, 1 is the welding strip, 2 is the intersection point, 3 is the bus bar, and 4 is the line laser. DETAILED DESCRIPTION

[0043] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0044] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0045] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0046] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0047] It should be understood that although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0048] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0049] According to a first specific embodiment of the present invention, the present invention provides a welding quality detection system including a welding quality detection device, a motion device and a solution device. The welding quality detection device includes a camera and a line laser transmitter.

[0050] The welding quality inspection device uses a 3D line scanning camera. The camera and line laser transmitter are set above the welding strip and fixed on the moving device. Multiple welding strips are set in parallel, and multiple welding strips have been welded. The welding quality of the welding strip is unknown and needs to be inspected. The situations of poor welding strip quality include: missing welding strip, welding strip too long, welding strip too short, welding strip offset, welding strip front end warping, welding strip rear end warping, welding strip fishhook warping, welding strip not welded.

[0051] The line laser emitter emits line lasers to the plurality of welding strips, so that the absolute value of the angle between the line laser and the length direction of the welding strip is 5-85 degrees.

[0052] The camera continuously captures the line laser to obtain multiple images.

[0053] The moving device is used to drive the welding quality detection device or multiple welding strips to move horizontally along a direction perpendicular to the length of the welding strips.

[0054] The calculating device is connected to the camera for communication, and is used for calculating the dot profiles of the multiple welding strips according to the captured images; and judging the welding quality according to the dot profiles of the multiple welding strips.

[0055] According to a second specific embodiment of the present invention, the present invention provides a method for detecting welding quality, using the welding quality detection system of the first specific embodiment. The detection method comprises the following steps:

[0056] A plurality of welding strips 1 are arranged in parallel, and the plurality of welding strips 1 have been welded to the bus bar 3. The width of the welding strip 1 is 0.1-2 mm. Preferably, the width of the welding strip 1 is 0.3 mm. The welding quality of the welding strip 1 is unknown and needs to be tested.

[0057] The camera and line laser transmitter are located above the welding strip 1, as shown in Figure 4 As shown, the camera and the line laser emitter move relative to the welding strip and move horizontally, and the movement direction is perpendicular to the length direction of the welding strip 1. The relative movement speed of the camera and the line laser emitter and the welding strip 1 is 0.1-3m / s. Preferably, the relative movement speed of the camera and the line laser emitter and the welding strip 1 is 1m / s.

[0058] The line laser emitter emits line laser 4 to multiple welding strips 1, so that the absolute value of the angle between the line laser 4 and the length direction of the welding strip 1 is 5-85 degrees. Preferably, the absolute value of the angle between the line laser 4 and the length direction of the welding strip 1 is 40-50 degrees, and more preferably 45 degrees. The line laser 4 forms an angle with the welding strip 1, so that the line laser 4 intersects with multiple welding strips 1 at the same time. Each shot can record the information of at least one intersection point 2 of a welding strip 1. Multiple shots can record the information of multiple intersection points 2 of a welding strip 1. After solving and splicing multiple shots, the point contour information of the entire welding strip 1 is obtained. Figure 4 In the figure, the enlarged image shows the camera taking multiple images and the irradiation position of the line laser. It can be seen that the line laser 4 forms an angle of 5-85 degrees with the welding strip 1, which can obtain more intersection information. Since the line laser 4 and the welding strip 1 form a certain angle, the outline of the welding strip 1 is completely scanned, and the detection accuracy is higher than that of the conventional detection scheme.

[0059] Usually, the existing methods are to make the line laser parallel to the welding strip. Each time the line laser hits the welding strip, there are more intersections with the same welding strip, and the information of the entire welding strip can be captured. It is believed that more welding strip information can be obtained in this way. The applicant broke this technical prejudice (inherent thinking) and achieved the unexpected technical effect of high detection accuracy and high efficiency detection by tilting the line laser.

[0060] This solution is based on the principle of 3D line scan camera. 3D line scan camera is mainly composed of line laser light source, 2D camera and imaging lens. 3D line scan camera includes: special light source (laser), special high-speed image acquisition system, special structure, special visual algorithm integrated together, a kind of visual system designed for detecting object contour. Line laser contour measurement sensor is a combination of line laser light source and high-speed industrial camera to obtain a cross-section contour image of the object to be measured, extract the contour on the image through image processing, calculate the physical coordinate information of the contour according to the principle of triangulation, and obtain the continuous contour (Profile) of the object through motion control and synthesize it to form a 3D point cloud (3D Cloud Point) of the object's appearance contour.

[0061] The camera and the line laser emitter continue to move at a uniform speed, and the camera continues to shoot the line laser 4 to obtain multiple images. The shooting frequency of the camera is 1000-5000Hz. Preferably, the shooting frequency of the camera is 3000Hz. In theory, the higher the frequency, the better. In fact, the full-frame frequency of the fastest product on the market is around 3000Hz. The smaller the distance between two adjacent points of the same welding strip captured, the more details are obtained. Spacing s = v / f, v is the movement speed of the camera and the line laser emitter, that is, the relative speed of the camera and the welding strip 1, and f is the camera sampling frequency.

[0062] like Figure 5 As shown, Figure 5 FIG. 2 shows the weld strip profile calculated after the laser line is set parallel to the weld strip in the prior art; Figure 6 As shown, Figure 6 The figure shows the weld strip profile calculated when the laser line of the present application forms an angle of 5-85 degrees with the weld strip.

[0063] The ideal welding strip cold soldering detection algorithm under the non-shaking state is H = L (average height of welding strip after welding) - B min (The minimum average height of the busbar area next to the welding ribbon). However, when the photovoltaic module is in motion, the busbar connected to the welding ribbon will have different degrees of waveform jitter, such as Figure 7 As shown in FIG. 1 , when the laser line is set parallel to the welding strip, the height difference L1 between the position one second before shooting and the shooting position in the next second is calculated as the sum of the real height H of the welding strip after welding and the height difference ΔH of the waveform before and after. The formula is: L1=H+ΔH; Figure 8 As shown, when the absolute value of the angle between the laser line setting and the welding strip is 5-85 degrees, the line laser with high collimation is mapped on the welding strip and the bus bar, and the real height contour line between the welding strip and the bus bar is depicted. The measured height value is L2≈H. The height difference calculated by this setting method is extremely close to the real height difference of the welding strip after welding in the non-jitter state.

[0064] The height value of the cold solder joint is: L≥1.5×H; where L represents the average height of the solder strip after soldering, and H represents the actual height of the solder strip after soldering, in μm. When L≥1.5×H, the solder strip is cold soldered.

[0065] The welding strip is short: D≤(2 / 3)×W; D is the length of the parallel welding strip on the busbar, and W is the width of the busbar, in mm. When D≤(2 / 3)×W, the welding strip is too short.

[0066] Overall offset of the welding strip: θ≥15°, where θ represents the angle between the camera laser line and the welding strip (the object being measured), in degrees. When θ≥15°, it means that the welding strip is crooked.

[0067] As shown in Table 1 below, Table 1 is a table of detection results of the prior art in which the laser line and the solder strip are arranged in parallel, and the serial number represents multiple results detected for the same solder strip.

[0068] Table 1

[0069]

[0070] As shown in Table 2 below, Table 2 is a table of detection results when the angle between the laser line and the solder strip of the present application is 5-85 degrees, and the serial number represents multiple results detected for the same solder strip.

[0071] Table 2

[0072]

[0073] Repeatability is the measurement of the same thing multiple times, which indicates the deviation of each solder strip height value from the average value, which is a percentage. Repeatability is the difference between the height value and the average value divided by the average value.

[0074] It can be seen that by adopting the method of this scheme, more accurate detection results can be obtained.

[0075] like Fig. 9 As shown, the dotted contours of multiple welding strips are calculated based on multiple captured images. Fig. 9 It can be seen that the detected contour is clear and no information is lost. Fig.10 This is the solution effect diagram of the existing technology. The edge collapses and the edge information is lost, which affects the detection result.

[0076] The welding quality can be judged based on the dot profiles of multiple welding strips. Based on the dot profiles of the welding strips, the poor quality of the welding strips can be judged, such as Fig.11 As shown, Fig.11 a means the solder strip is missing. Fig.11 b: The welding strip is too long. Fig.11 c: The welding strip is too short. Fig.11 d is the strip offset, Fig.12 a is the warping of the front end of the welding strip. Fig.12 b is the warping of the rear end of the welding strip. Fig.12 c is the fishhook-shaped warping of the welding strip, Fig.12 d: The welding strip is not welded.

[0077] The present invention tilts the line laser so that there is a certain angle between the line laser and the length direction of the welding strip, which can extract more contour information with a detection accuracy of 3μm. Without increasing the camera frame rate and keeping the camera hardware parameters unchanged, not only can more scanning points be obtained, but also the calculation error caused by the macro-jitter of the moving object under actual production conditions can be reduced, thereby obtaining higher detection accuracy and further judging the actual welding quality.

[0078] The exemplary embodiments of the present invention are specifically shown and described above. It should be understood that the present invention is not limited to the detailed structure, configuration or implementation method described herein; on the contrary, the present invention is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A welding quality detection method, using a welding quality detection device, the welding quality detection device comprising a camera and a line laser transmitter, characterized in that: The following steps are involved: A plurality of welding strips are arranged in parallel, and a plurality of welding strips have been welded; The welding quality detection device is located above the welding strip, and the welding quality detection device or the welding strip moves horizontally, and the moving direction is perpendicular to the length direction of the welding strip; The line laser emitter emits line lasers to the plurality of welding strips, so that the absolute value of the angle between the line laser and the length direction of the welding strip is 5-85 degrees; The welding quality inspection device or the welding strip is in continuous motion, and the camera continuously shoots the line laser to obtain multiple images; Calculate the dotted contours of multiple welding strips based on multiple captured images; The welding quality is judged based on the dotted profiles of multiple welding strips.

2. The welding quality detection method according to claim 1, characterized in that: The welding quality detection device adopts a 3D line laser scanning camera.

3. The method for detecting welding quality according to claim 1, characterized in that: The width of the welding strip is 0.1-2 mm.

4. The method for detecting welding quality according to claim 1, characterized in that: The relative movement speed between the welding quality detection device and the welding strip is 0.1-3m / s.

5. The method for detecting welding quality according to claim 1, characterized in that: The shooting frequency of the camera is 1000-5000 Hz.

6. A welding quality detection system, characterized in that: The detection system detects welding quality using any one of the welding quality detection methods in claims 1-5.

7. The welding quality detection system according to claim 6, characterized in that: It includes a welding quality detection device, a motion device and a solving device; the welding quality detection device includes a camera and a line laser transmitter; A camera and a line laser transmitter are arranged above the welding strip and fixed on a moving device; a plurality of welding strips are arranged in parallel, and a plurality of welding strips have been welded; The line laser emitter emits line lasers to the plurality of welding strips, so that the absolute value of the angle between the line laser and the length direction of the welding strip is 5-85 degrees; The camera continuously shoots the line laser to obtain multiple images; The moving device is used to drive the welding quality detection device or the plurality of welding strips to move horizontally along a direction perpendicular to the length of the welding strips; The calculating device is connected to the camera for communication, and is used for calculating the dot profiles of the multiple welding strips according to the captured images; and judging the welding quality according to the dot profiles of the multiple welding strips.

8. The welding quality detection system according to claim 7, characterized in that: The welding quality detection device adopts a 3D line laser scanning camera.

Images