A PLC-based welding steel plate surface quality detection system

Abstract

The present invention discloses a PLC-based welding steel plate surface quality detection system, comprising a detection device, wherein the detection device is arranged in multiple positions around the to-be-detected part, and the detection device is controlled by a control system, and the detection results collected by the detection device in real time are fed back to a processing system in the control system so as to make a judgment on the surface quality of the to-be-detected part; the detection device performs multi-dimensional detection through multiple camera positions, collects images of the to-be-detected part, and then processes the images through an operator, and feeds back the output information to the processing system. The present invention provides a PLC-based welding steel plate surface quality detection system, which uses a camera with machine vision to perform multi-camera multi-dimensional automated detection, thereby being able to perform comprehensive and accurate detection of quality problems on the surface of the welding steel plate.

Description

Technical Field

[0001] The invention relates to the field of a PLC-based welding steel plate surface quality detection system. Background Art

[0002] When processing welded steel plates, it is an important step to inspect the surface of the welded steel plates. The surface rust and dirt of the welded steel plates at the beginning, as well as the welding marks after welding, whether there are cracks in the welding joints, and whether there is burn-through in the welded steel plates all need to be inspected before judging whether they are qualified, so as to prevent defective steel plates from affecting their applicability or making them unsuitable after welding. Today's inspection methods are usually to take pictures with a camera, then check the defects on the surface of the steel plates, and then judge whether they are qualified. However, the lack of accuracy of single camera inspection can lead to misjudgment. Summary of the invention

[0003] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a PLC-based welding steel plate surface quality inspection system, which utilizes a camera with machine vision to perform multi-position and multi-dimensional automated inspection, thereby enabling comprehensive and accurate inspection of quality issues on the surface of welding steel plates.

[0004] Technical solution: To achieve the above purpose, the technical solution of the present invention is as follows:

[0005] A PLC-based welding steel plate surface quality detection system comprises a detection device, which is arranged in various positions around a workpiece to be detected. The detection device is controlled by a control system, and the detection results collected by the detection device in real time are fed back to a processing system in the control system so as to make a judgment on the surface quality of the workpiece to be detected; the detection device performs multi-dimensional detection through multiple camera positions, collects images of the workpiece to be detected, and then processes the images through an operator, and feeds back the output information to the processing system.

[0006] Furthermore, the control system includes a main circuit, a three-phase power supply of the main circuit is connected in series with a plurality of motors; the three-phase power supply is electrically connected to a fuse FU through a switch QF, the fuse FU is electrically connected to a thermal relay FR through a plurality of parallel contactors KM, and the thermal relay FR is electrically connected to the motor.

[0007] Furthermore, contactor KM1 is the main contact of the forward AC contactor. When contactor KM1 is turned on, the motor M1 is connected to the three-phase current of the forward phase sequence UVW, and the motor M1 rotates forward; contactor KM2 is the reverse contact point. When contactor KM2 is turned on, the motor M1 is connected to the three-phase current of the reverse phase sequence WVU, and the motor M1 reverses.

[0008] Furthermore, the main circuit includes a control circuit, in which the line N is connected to the contactor KM through a button switch SB, multiple parallel contactors KM are electrically connected to the thermal relay FR through multiple parallel button switches SB, and the thermal relay FR is electrically connected to the line L through a fuse FU; the multiple parallel contactors KM are in an interlocking relationship.

[0009] Furthermore, the operator processing of the image is to perform preprocessing first, then perform data processing on the image on the software to obtain a comparison template, and then load the comparison template into the comparison program for comparison; the operator processing steps of the image are: 1) overall formatting and saving of the image; 2) cropping of image specification pixels; 3) correction of the grayscale value of the image; 4) expansion of the boundaries of defective pixels on the image surface; 5) standardization and denoising of the image; 6) morphological analysis and processing of the image; 7) binarization of the image; 8) extraction of defect features in the image; 9) obtaining the defect location.

[0010] Furthermore, the detection device includes a movable platform and a camera; the movable platform is spliced ​​by a plurality of magnetically connected bases, and the plurality of bases can be moved individually; the plurality of cameras are arranged on the base through an adjustment structure, and the corresponding cameras can be driven to move to a specified position through the base; the adjustment structure is provided with a plurality of bar light sources, and the plurality of bar light sources are located around the camera; during detection, the irradiation end of the bar light source is adjusted toward the surface of the part to be detected through the adjustment structure, and the shooting angle of the camera and the distance between the part to be detected are adjusted.

[0011] Furthermore, multiple bases are arranged around the part to be detected, and multiple cameras and strip light sources are used to detect the part to be detected from multiple directions; a matching groove with a gradually increasing notch is provided in the middle of the base, and the bottom end of the support column of the adjustment structure is embedded in the matching groove, and the swing device in the matching groove drives the support column to swing, and a card slot is provided on the side wall of the support column, and the card slot is provided on the side of the support column facing the part to be detected, and card slots are respectively provided on both sides of the support column relative to the part to be detected; a sliding block is slidably arranged in the card slot; the driving end of the telescopic device at the bottom of the card slot is drivingly connected to the bottom surface of the sliding block; the camera and the strip light source are respectively fixed on the side walls of the sliding block through the connecting structure, and multiple sliding blocks drive the camera and the strip light source to adjust up and down through the connecting structure.

[0012] Furthermore, the connecting structure includes an arc-shaped rod, one end of which is fixed on the side wall of the sliding block, and the other end of which is offset toward the direction of the part to be detected, serving as an adjustment end, and the adjustment end is provided with a strip light source through a universal coupling; the strip light sources on both sides of the support column are arranged relative to each other, and the irradiation ends of the multiple strip light sources are facing the part to be detected.

[0013] Furthermore, the connection structure also includes a turntable, a rotating device on the sliding block facing the inspected part is drivingly connected to the turntable, a camera is arranged in the middle of the turntable through a universal coupling, and a plurality of strip light sources are relatively arranged on the edge of the turntable through a plurality of universal couplings, and the camera is located at the center position of the line connecting the plurality of relative strip light sources.

[0014] Beneficial effects: The present invention first controls the shooting angle of the on-site camera and the distance adjustment between the photographed object, that is, the so-called object distance, according to the condition restrictions of the on-site scene; the object imaging is clearer, and the obtained image can be more conducive to finding defects on the surface of the welded steel plate. The camera is used to replace the human eye to perform real-time detection and monitoring management on the output welded steel plates. Through the fill light of multiple strip light sources and the multi-angle and multi-directional shooting of the steel plate surface by multiple cameras, defective welded steel plates can be screened out in time; the surface rust and surface dirt of the welded steel plate at the beginning, as well as the welding marks after welding, whether there are cracks in the welding joint, and whether the welded steel plate has burn-through phenomenon are monitored for qualified and unqualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Attached Figure 1 It is the basic system of camera machine vision;

[0016] Attached Figure 2 Main circuit schematic diagram;

[0017] Attached Figure 3 This is the control circuit schematic diagram;

[0018] Attached Figure 4 It is a diagram of the operator processing steps of the image;

[0019] Attached Figure 5 This is the structural diagram of the detection device. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] As attached Figure 1-5 : A PLC-based welding steel plate surface quality inspection system, including an inspection device, which is arranged in multiple positions around the workpiece to be inspected, and is controlled by a control system. The inspection results collected by the inspection device in real time are fed back to a processing system in the control system so as to make a judgment on the surface quality of the workpiece to be inspected; the inspection device performs multi-dimensional inspection through multiple cameras, collects images of the workpiece to be inspected, and then processes the images through operators, and feeds back the output information to the processing system, which is a PLC control module.

[0022] When inspecting the surface quality of welded steel plates (to be inspected), firstly, the shooting angle of the on-site camera and the distance between the object being photographed, that is, the so-called object distance, are controlled according to the conditions of the on-site scene; so that the imaging of the object is clearer, and the resulting image can be more conducive to finding defects on the surface of the welded steel plates. The camera is used to replace the human eye to conduct real-time inspection and monitoring management of the output welded steel plates, and defective welded steel plates can be screened out in time; the qualified and unqualified are monitored based on the initial surface rust and surface dirt of the welded steel plates, as well as the welding marks after welding, whether there are cracks in the welding joints, and whether there is burn-through in the welded steel plates.

[0023] The control system includes a main circuit, the three-phase power supply of the main circuit is connected in series with a plurality of motors; the three-phase power supply is electrically connected to the fuse FU through a switch QF, the fuse FU is electrically connected to the thermal relay FR through a plurality of parallel contactors KM, and the thermal relay FR is electrically connected to the motor. The U, V, and W are three-phase AC power supply voltages of 380V to ensure the rated working voltage of the motor. QF is a switch connected to the three-phase power supply, which is mainly capable of controlling the on and off functions of the three-phase power supply.

[0024] Contactor KM1 is the main contact of the forward AC contactor. When contactor KM1 is turned on, motor M1 is connected to the three-phase current of the forward phase sequence UVW, and motor M1 rotates forward; contactor KM2 is the reverse contact point. Contactor KM2 has an interlocking relationship with contactor KM1 in the control circuit. When contactor KM2 is turned on, motor M1 is connected to the three-phase current of the reverse phase sequence WVU, and motor M1 reverses. The control of the overall main circuit correctly and accurately makes the servo motor run stably and continuously based on the mutual protection of software and hardware.

[0025] The main circuit includes a control circuit, in which the line N is connected to the contactor KM through a button switch SB, and multiple parallel contactors KM are electrically connected to the thermal relay FR through multiple parallel button switches SB, and the thermal relay FR is electrically connected to the line L through a fuse FU; multiple parallel contactors KM are interlocked. The control circuit is mainly completed by using the mutual interlocking of software and hardware to ensure the correct operation of the entire system. In terms of hardware, the interlocking of the contactor is used to complete the hardware protection; at the same time, the software interlocking method is also used for protection when programming.

[0026] The detection system of welded steel plate surface defects can work stably and safely as required on a specific production line, and can complete the required welded steel plate surface quality detection effect within the specified time period. Based on the surface quality of the given reference object as the standard, the image calculation, detection, analysis and corresponding step judgment are given, which are divided into two categories: qualified and unqualified.

[0027] The operator processing of the image is to perform preprocessing first, then perform data processing on the image on the software to obtain a comparison template, and then load the comparison template into the comparison program for comparison; the operator processing steps of the image are: 1) overall formatting and saving of the image; 2) cropping of image specification pixels; 3) correction of the grayscale value of the image; 4) expansion of the boundary of defective pixel points on the image surface; 5) standardization and denoising of the image; 6) morphological analysis and processing of the image; 7) binarization of the image; 8) extraction of defect features in the image; 9) obtaining the defect location.

[0028] During the welding process, rusty steel plates are used for welding. If the surface of the welded steel plate is severely rusted, it will have a certain impact on the welding results. For example, the rusty part will make the weld more likely to produce pores, which will affect the combination between the two welded plates and produce slag inclusions, which will eventually lead to defects such as poor fusion of the welded plates. The surface of the welded steel plate is not only rusty, but also has oil stains and other dirt attached to the welded steel plate. The oil stain defect mainly detects the location of the oil stain on the surface of the welded steel plate (the detection range is that the area of ​​the oil stain is not less than 6% of the entire steel plate); if the welded steel plate has oil stains and other dirt defects, welding will cause pores in the welded weld, and it is very likely to cause false welding, which will greatly reduce the strength of the welded structure and shorten the service life. If this phenomenon occurs in an important structure, it will cause an accident with very serious consequences. This is very demanding for welding products with high welding sealing properties.

[0029] Finding the location of the weld mark is conducive to a clearer understanding of the situation of the weld mark welding interface, and is also conducive to targeted analysis and detection of defect targets. After finding the location of the weld mark of the welded steel plate, the characteristic screening of the location defects of the weld mark is carried out. The first is the weld mark crack. If welding cracks appear during welding, this will cause great harm to production operations. Not only will this cause great on-site accidents, because welding cracks are one of the most dangerous deficiencies in welding projects; the appearance of welding welds in welding projects greatly reduces the bearing capacity of the welded structure. At the same time, the appearance of welding welds increases the contact area between the welding interface and the outside world, making the welded part more susceptible to corrosion. It may become a potential danger in future work. When the welded steel plate has a welding burn-through phenomenon, it is basically the burn-through of the welding base material during welding, which obviously causes some irreparable damage to the welded steel plate.

[0030] The detection device includes a movable platform and a camera 2; the movable platform is spliced ​​by multiple magnetically connected bases 1, and the multiple bases 1 can be moved separately; the multiple cameras 2 are arranged on the base 1 through an adjustment structure 3, and the corresponding camera 2 can be driven to move to a specified position through the base 1; the adjustment structure 3 is provided with multiple strip light sources 4, and the multiple strip light sources 4 are located around the camera 2; during detection, the irradiation end of the strip light source 4 is adjusted to face the surface of the to-be-detected part through the adjustment structure 3, and the shooting angle of the camera 2 and the distance between the to-be-detected part are adjusted; the camera is adjusted to the clearest position and angle, thereby improving the quality of the captured image and improving the accuracy of detection.

[0031] A plurality of bases 1 are arranged around the part to be detected, and a plurality of cameras 2 and strip light sources 4 detect the part to be detected from multiple directions; a matching groove 11 with a gradually increasing notch is provided in the middle of the base 1, and the bottom end of the support column 31 of the adjustment structure 3 is embedded in the matching groove 11, and the swing device in the matching groove 11 drives the support column 31 to swing, and a card slot 311 is provided on the side wall of the support column 31, and the card slot 311 is provided on the side of the support column 31 facing the part to be detected, and the card slots 311 are respectively provided on both sides of the support column 31 relative to the part to be detected; a sliding block 312 is slidably provided in the card slot 311; the telescopic device driving end at the bottom of the card slot 311 is drivingly connected to the bottom surface of the sliding block 312; the camera 2 and the strip light source 4 are respectively fixed on the side wall of the sliding block 312 through the connecting structure 5, and the plurality of sliding blocks 312 respectively drive the camera 2 and the strip light source 4 to adjust up and down through the connecting structure 5. The control system can control the telescopic device. The driving end of the telescopic device drives the sliding block to slide up and down in the slot. The sliding block drives the strip light source to move to a position obliquely above the part to be inspected, and the irradiation end of the strip light source faces the surface of the part to be inspected, and the light source is irradiated to the welded steel plate, etc.; then the movement of the sliding block drives the camera to move into place and aim at the surface of the welded steel plate. Each strip light source and camera illuminates the welded steel plate from different directions. After multiple lighting test selections, the camera can obtain high-quality images and can detect all aspects of the welded steel plate surface.

[0032] The connecting structure 5 includes an arc-shaped rod 51, one end of which is fixed on the side wall of the sliding block 312, and the other end of which is offset toward the direction of the part to be detected, and is an adjustment end. The adjustment end is provided with a strip light source 4 through a universal coupling, and is driven by a motor on the adjustment end; the strip light sources 4 on both sides of the support column 31 are arranged relatively, and the irradiation ends of the multiple strip light sources 4 are oriented toward the part to be detected. Through the control of the control system, the relative strip light sources are adjusted to be staggered up and down, and the strip light sources on the adjacent support columns are staggered up and down to complement each other, so as to improve the brightness of the light irradiated by the multiple strip light sources, thereby increasing the image quality taken by the camera.

[0033] The connecting structure 5 also includes a turntable 52, and a rotating device on the sliding block 312 facing the inspected part is drivingly connected to the turntable 52. A camera 2 is arranged in the middle of the turntable 52 through a universal coupling, and a plurality of strip light sources 4 are relatively arranged on the edge of the turntable 52 through a plurality of universal couplings, which are driven by a motor on the turntable, and the camera 2 is located at the center position of the connecting line of the plurality of relative strip light sources 4; after the driving sliding block drives the turntable to be adjusted up and down, the rotating device drives the turntable to rotate, so that the camera and the strip light source are illuminated at the most suitable angle. For relatively inclined welded steel plates, it is necessary to adjust the inclination of the camera and the strip light source to face the surface of the welded steel plate. On the one hand, the inclination of the support column can be adjusted to adapt to the inclination angle of the welded steel plate, and on the other hand, the inclination of the strip light source and the camera can be adjusted by the turntable to adapt to the concave and convex surface of the welded steel plate, so as to improve the accuracy of surface quality detection of the welded steel plate.

[0034] When using a camera for image detection, select the appropriate light source for lighting test. After multiple lighting test selections, a camera with relatively high shooting quality can obtain a high-quality image to carry out the next specific work. The surface reflectivity of the welded steel plate uses a strip light source to illuminate on all sides, which can make the captured image more clearly reflect the weld position on the welded steel plate and the surrounding effects. Moreover, the strip light source is small in size and more flexible and convenient to use, and can be used in different locations and occasions.

[0035] The whole set of inspection equipment uses multi-position machine inspection in terms of vision. It not only inspects, analyzes and selects the incoming welded steel plates, only those that meet the requirements are allowed to enter the next link, but also conducts targeted analysis on the weld seams after welding is completed; making the whole set of work system clearly divided and the efficiency optimized. The workflow diagram of the machine vision basic system is shown in the figure of the machine vision basic system.

[0036] Using CCD industrial cameras to scan and inspect the welded steel plates in multiple dimensions can help us understand the current situation of the welded steel plates more clearly. Using image processing technology, we can process the real-time scan results of industrial cameras, that is, high-quality images. Using Halcon software, we can optimize, filter, segment and process the images. The final inspection results are fed back to the PLC to make the next step of execution judgment, and the inspection defect results can also be displayed in the engineering files.

[0037] In the industrial field, most of the images are saved based on the high-quality image format of the camera, Bmp format, which is the most standard image file format accepted by computers. The image has a large amount of information and is basically uncompressed. Bmp format is the first-hand image data obtained after shooting with a camera. Then, according to the characteristics that meet the requirements, the Bmp format image is converted into the image format tiff format that can be widely used and compatible with multiple software used. The tiff format image is the most widely used image file across multiple Mac and PC platforms, and at the same time, it has the advantages of the Bmp format, and the memory occupied is greatly reduced, which can meet the requirements of image storage, conversion and transmission. After the image is saved completely, it is the preprocessing stage of the image. The overall image processing process is mainly to process the image data on the Halcon software to obtain a comparison template; finally, the template is loaded into the comparison program to play a reference comparison role, so that the location of the surface defects of the steel plate can be found and whether the surface of the welded steel plate is qualified can be determined.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. A person skilled in the art may make several improvements and changes without departing from the above principles of the present invention, and these improvements and changes are also considered to be within the protection scope of the present invention.

Claims

1. A PLC-based welding steel plate surface quality detection system, characterized by: The system comprises a detection device, which is arranged in various positions around the part to be detected. The detection device is controlled by a control system, and the detection results collected by the detection device in real time are fed back to a processing system in the control system so as to make a judgment on the surface quality of the part to be detected. The detection device performs multi-dimensional detection through multiple camera positions and collects images of the part to be detected. Then, the image is processed by an operator and the output information is fed back to the processing system. The detection device comprises a camera (2) and a support column (31); a slot (311) is provided on a side of the support column (31) facing the part to be detected, and slots (311) are respectively provided on both sides of the support column (31) facing the part to be detected; a sliding block (312) is slidably provided in the slot (311); the camera (2) and the strip light source (4) are respectively fixed on the side walls of the sliding block (312) via a connecting structure (5); the strip light sources (4) on both sides of the support column (31) are arranged opposite to each other; the connecting structure (5) further comprises a turntable (52), a rotating device on the sliding block (312) facing the part to be detected is drivingly connected to the turntable (52), a camera (2) is provided in the middle of the turntable (52) via a universal coupling, a plurality of strip light sources (4) are relatively provided on the edge of the turntable (52) via a plurality of universal couplings, and the camera (2) is located at the center position of the connection line of the plurality of opposite strip light sources (4); Fill light optimization method in the specific process of image acquisition: The strip light sources (4) on both sides of the support column (31) are moved to a position obliquely above the part to be detected, and the irradiation ends of the strip light sources (4) are directed toward the surface of the part to be detected, and the strip light sources (4) on both sides of the support column (31) that are opposite to each other are adjusted to be staggered up and down, while the strip light sources on adjacent support columns are staggered up and down to complement each other; Then, the sliding block (312) is driven to drive the turntable (52) to adjust up and down to the correct position, thereby driving the camera (2) to move to the correct position and aim at the surface of the welded steel plate; the rotating device drives the turntable (52) to rotate and adjust the angle of the strip light source (4) on the turntable.

2. According to the PLC-based welding steel plate surface quality detection system of claim 1, it is characterized by: The control system includes a main circuit, a three-phase power supply of the main circuit is connected in series with a plurality of motors; the three-phase power supply is electrically connected to a fuse FU via a switch QF, the fuse FU is electrically connected to a thermal relay FR via a plurality of parallel contactors KM, and the thermal relay FR is electrically connected to the motor.

3. The PLC-based welding steel plate surface quality detection system according to claim 2 is characterized in that: Contactor KM1 is the main contact of the forward AC contactor. When contactor KM1 is turned on, the three-phase current of the forward phase sequence UVW is connected to the motor M1, and the motor M1 rotates forward; contactor KM2 is the reverse contact point. When contactor KM2 is turned on, the three-phase current of the reverse phase sequence WVU is connected to the motor M1, and the motor M1 reverses.

4. The PLC-based welding steel plate surface quality detection system according to claim 3 is characterized in that: The main circuit includes a control circuit, in which the line N is connected to the contactor KM through a button switch SB, multiple parallel contactors KM are electrically connected to the thermal relay FR through multiple parallel button switches SB, and the thermal relay FR is electrically connected to the line L through a fuse FU; the multiple parallel contactors KM are in an interlocking relationship.

5. The PLC-based welding steel plate surface quality detection system according to claim 4 is characterized in that: The operator processing of the image is to perform preprocessing first, then perform data processing on the image on the software to obtain a comparison template, and then load the comparison template into the comparison program for comparison; the operator processing steps of the image are: 1) overall formatting and saving of the image; 2) cropping of image specification pixels; 3) correction of the grayscale value of the image; 4) expansion of the boundary of defective pixel points on the image surface; 5) standardization and denoising of the image; 6) morphological analysis and processing of the image; 7) binarization of the image; 8) extraction of defect features in the image; 9) obtaining the defect location.

6. The PLC-based welding steel plate surface quality detection system according to claim 5 is characterized in that: The detection device comprises a movable platform and a camera (2); the movable platform is composed of a plurality of magnetically connected bases (1), and the plurality of bases (1) can be moved independently; the plurality of cameras (2) are arranged on the base (1) via an adjustment structure (3), and the base (1) can drive the corresponding camera (2) to move to a specified position; the adjustment structure (3) is provided with a plurality of strip light sources (4), and the plurality of strip light sources (4) are located around the camera (2); During detection, the irradiation end of the strip light source (4) is adjusted toward the surface of the object to be detected by adjusting the adjustment structure (3), and the shooting angle of the camera (2) and the distance between the object to be detected are adjusted.

7. The PLC-based welding steel plate surface quality detection system according to claim 6 is characterized in that: A plurality of bases (1) are arranged around the object to be detected, and a plurality of cameras (2) and strip light sources (4) detect the object to be detected from multiple directions; a matching groove (11) with a gradually increasing notch is provided in the middle of the base (1); the bottom end of the support column (31) of the adjustment structure (3) is embedded in the matching groove (11); a swing device in the matching groove (11) drives the support column (31) to swing; a telescopic device driving end at the bottom of the slot (311) is drivingly connected to the bottom surface of the sliding block (312); the camera (2) and the strip light source (4) are respectively fixed to the side wall of the sliding block (312) through the connecting structure (5); and the plurality of sliding blocks (312) respectively drive the camera (2) and the strip light source (4) to adjust up and down through the connecting structure (5).

8. The PLC-based welding steel plate surface quality detection system according to claim 7 is characterized in that: The connection structure (5) comprises an arc-shaped rod (51), one end of the arc-shaped rod (51) is fixed to the side wall of the sliding block (312), and the other end of the arc-shaped rod (51) is offset in the direction of the part to be detected and is an adjustment end, and the adjustment end is provided with a strip light source (4) via a universal coupling; and the irradiation ends of the plurality of strip light sources (4) are oriented towards the part to be detected.

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