Automatic surface pretreatment device and method for improving laser visual tracking precision of welding seam

Abstract

The automatic surface pretreatment device comprises a U-shaped rib and a laser cleaning device, the bottom of the U-shaped rib is placed on a supporting mechanism, a transmission mechanism is arranged at the top of the U-shaped rib, a U-shaped rib conveying driving wheel is connected to the bottom of the transmission mechanism, and the U-shaped rib conveying driving wheel is in transmission connection with the two sides of the U-shaped rib correspondingly; the laser cleaning device comprises laser cleaning machining heads, the laser cleaning machining heads are arranged on the two sides of the U-shaped rib respectively, and a laser contour scanner is arranged on the side, away from the U-shaped rib, of the laser cleaning machining head on one side. The surface roughness of the steel plate is regulated and controlled by adjusting laser cleaning process parameters such as laser power, cleaning speed and cleaning times, the light reflection phenomenon in the laser visual tracking welding process is reduced, and therefore the follow-up welding seam tracking precision is improved; the automation degree is high, a database of important parameters such as U rib materials, the laser cleaning process, the cleaning surface quality and the welding deviation is conveniently established, and an intelligent digital workshop can be built easily.

Description

Technical Field

[0001] The present invention relates to an automatic surface pretreatment device and method, and in particular to an automatic surface pretreatment device and method for improving the accuracy of laser visual tracking of welds. Background Art

[0002] Orthotropic steel bridge deck is a commonly used main unit in the domestic bridge manufacturing industry. It has been widely used in large-span bridges at home and abroad due to its light weight, large ultimate bearing capacity and wide range of applications. Orthotropic bridge deck is mainly composed of steel structure panel and cross beams and longitudinal ribs welded to it. The cross beam is mainly a diaphragm, and the longitudinal rib is mainly a U-shaped rib structure. With the rapid development of manufacturing technology in my country, the manufacturing of orthotropic steel bridge deck has gradually developed from a manufacturing mode dominated by manual welding to a manufacturing mode dominated by mechanization and automation, and further developed towards intelligent manufacturing assisted by machine vision and artificial intelligence. Under this technical background, intelligent welding with weld laser vision tracking as the core technology has attracted much attention in the field of bridge engineering. Weld laser vision tracking is similar to installing eyes on the welding actuator. Its main function is to identify and locate the weld position at the starting welding point. During the welding process, the deviation information is fed back to the actuator in real time according to the height and left and right changes of the weld, so as to ensure that the welding gun is always aligned with the weld, thereby ensuring the welding quality. The key link of laser tracking is image processing. However, during the welding process, the intense arc, spatter, and smoke will affect the signal-to-noise ratio and clarity of image acquisition. At the same time, the reflective and light-absorbing properties of the workpiece material itself, surface oil, and grinding scratches will affect the signal acquisition of the laser stripes, thereby increasing the difficulty of image processing and limiting the accuracy of laser tracking. Therefore, from the perspective of improving the accuracy of laser visual tracking of welds, it is necessary to carry out targeted surface pretreatment of the area to be welded. However, there are few public reports on this aspect. Usually, the surface of the U-rib for bridges is sprayed with inorganic silicate anti-rust paint with a thickness of about 30 to 40 μm, and it is inevitable that there are pollutants such as rust, iron oxide, oil, and moisture. In order to prevent the formation of welding defects such as pores, cracks, and inclusions, the bridge deck unit must not only thoroughly remove these harmful pollutants in the area to be welded before welding, but also effectively remove the anti-rust paint sprayed on the surface when the steel plate is supplied. The traditional cleaning method in the bridge industry is mainly mechanical grinding. However, this method is not only noisy and dusty, but also has low work efficiency. In addition, surface reflections and grinding scratches will have an adverse effect on the signal acquisition of laser stripes, reducing the accuracy of laser visual tracking of welds. Therefore, it is of great engineering value to develop a set of efficient and environmentally friendly surface pretreatment methods that can effectively remove rust, iron oxide, oil, moisture and raw material anti-rust paint in the welding area and ensure the accuracy of laser visual tracking. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to propose a surface automated pretreatment device and method for improving the accuracy of weld seam laser vision tracking, so as to improve the accuracy of weld seam tracking.

[0004] Technical solution: The present invention includes a U-rib and a laser cleaning device. The bottom of the U-rib is placed on a supporting mechanism. A transmission mechanism is provided on the top of the U-rib. The bottom of the transmission mechanism is connected to a U-rib conveying driving wheel. The U-rib conveying driving wheels are respectively connected to the two sides of the U-rib for transmission. The laser cleaning device includes a laser cleaning processing head. The laser cleaning processing heads are respectively arranged on both sides of the U-rib, and a laser contour scanner is arranged on the side away from the U-rib on one side of the laser cleaning processing head.

[0005] The support mechanism comprises a U-rib conveying bracket, which is arranged on both sides of the U-rib, and a plurality of U-rib transmission rollers are connected between the U-rib conveying brackets on both sides.

[0006] The U-rib conveying bracket is provided with a pneumatic clamp for clamping and limiting.

[0007] The surface of the U-rib transmission roller is provided with U-ribs for transmitting the U-ribs.

[0008] The transmission mechanism comprises a walking gantry, which is installed on a ground rail, and a U-rib conveying driving wheel is connected to the bottom of the walking gantry to realize the transmission of the U-rib.

[0009] The U-rib conveying driving wheel is installed on the walking gantry through a linear slide rail and a connecting rod, can move in the horizontal and vertical directions, and can be driven to rotate by a motor to realize the transmission of the U-rib.

[0010] The laser cleaning processing head is connected to the laser cleaning host system, and the laser cleaning process parameters are regulated by the laser cleaning host system to perform cleaning work.

[0011] The laser cleaning processing head is installed on a movable bracket and its position is adjustable so as to perform laser positioning and focusing before laser cleaning.

[0012] The laser cleaning host system and the laser profile scanner are connected to the master control host, and are responsible for collecting information such as the U rib 1 material number, laser cleaning power, laser cleaning speed, and surface geometric features after cleaning, and archiving each set of data to form a U rib laser cleaning database.

[0013] A surface automated pretreatment method for improving the accuracy of weld laser visual tracking, comprising the following steps:

[0014] Step 1: Place the U-rib that needs surface pretreatment on the transmission roller of the U-rib conveying bracket and position it through the pneumatic clamp system of the conveying bracket;

[0015] Step 2: Adjust the slide rail mechanism connected to the U-rib conveying driving wheel so that the U-rib conveying driving wheel presses the two sides of the U-rib respectively;

[0016] Step 3: Pause when the front end of the U rib is transported to the position allowed by the laser cleaning processing head;

[0017] Step 4: Set the cleaning laser power to 3000-5000W, adjust the position of the laser cleaning processing head, and focus the cleaning laser; set the driving wheel rotation linear speed to 30-50mm / s, and start the laser cleaning at the same time, starting the U-rib laser cleaning with a laser power of 3000-5000W and a cleaning speed of 30-50mm / s;

[0018] Step 5: When the cleaned U-rib segment is transported to the laser profile scanner station, the laser profile scanner is started to perform segmented three-dimensional profile measurement of the U-rib laser part, and the three-dimensional profile data and roughness data are saved;

[0019] Step 6: If the surface roughness after laser cleaning is within the range of 5.5-7.5 μm, the U-rib will be transported to the unloading area for temporary storage after the entire U-rib is cleaned for later laser tracking welding; if the roughness is too large, the laser power can be increased, the cleaning speed can be reduced, or the number of cleaning times can be increased;

[0020] Step 7: The cleaned U-rib is subjected to single-sided gas shielded welding at the ship position, and the laser tracking system is used in the welding process;

[0021] Step 8: After welding is completed, perform segmented welding deviation statistics.

[0022] Beneficial effects: The present invention utilizes high-frequency and high-energy laser pulses to irradiate the surface of the steel plate, causing the rust spots, coatings or oil stains on the surface of the steel plate to evaporate or peel off instantly, thereby achieving the purpose of peeling, breaking and falling off the pollutants from the surface of the substrate without damaging the steel plate. By adjusting the laser cleaning process parameters such as laser power, cleaning speed, and number of cleanings, the surface roughness of the steel plate is regulated, and the reflection phenomenon in the laser vision tracking welding process is reduced, thereby improving the accuracy of subsequent weld tracking; the degree of automation is high, the production process is green and environmentally friendly, and there is no noise pollution; the degree of digitization is high, and it is easy to establish a database of important parameters such as U-rib materials, laser cleaning processes, cleaning surface quality, and weld deviation, which is helpful to create an intelligent digital workshop. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2The figures are statistical graphs of surface roughness after 1, 2, and 3 laser cleaning times, respectively; (a) is a statistical graph of surface roughness after 1 laser cleaning; (b) is a statistical graph of surface roughness after 2 laser cleanings; (c) is a statistical graph of surface roughness after 3 laser cleanings;

[0025] Figure 3 The following are scanning electron microscope photos of the surface morphology after 1, 2, and 3 laser cleaning times, respectively; (a) is a scanning electron microscope photo of the surface morphology after 1 laser cleaning; (b) is a scanning electron microscope photo of the surface morphology after 1 laser cleaning; (c) is a scanning electron microscope photo of the surface morphology after 1 laser cleaning;

[0026] Figure 4 This is a statistical chart comparing the welding offset after the surface treatment method of the present invention and the traditional mechanical grinding treatment. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] like Figure 1 As shown, the surface automated pretreatment device for improving the laser visual tracking accuracy of weld seams of the present invention comprises a U-rib transmission roller 2, a U-rib conveying bracket 3, a walking gantry 4, a ground rail 5, a U-rib conveying driving wheel 6, a laser cleaning processing head 7, a laser cleaning host system 8, a laser contour scanner 9, and a master control host 10. The walking gantry 4 is mounted on the ground rail 5; the U-rib conveying driving wheel 6 is mounted on the walking gantry 4, and the U-rib conveying driving wheel 6 is mounted on the walking gantry 4 through a linear slide rail and a connecting rod, and can move in the horizontal and vertical directions, and can be driven to rotate by a motor to realize the transmission of the U rib 1; the U rib 1 is grasped and placed on the U-rib conveying bracket 3, and is clamped and limited by the pneumatic clamp on the U-rib conveying bracket 3. The U-rib conveying bracket 3 is provided with multiple sets of U-rib transmission rollers 2 for transmitting the U rib 1. When the U rib 1 is transferred to the position of the laser cleaning processing head 7, the laser cleaning host system 8 is used to adjust the laser cleaning process parameters for cleaning. There are two sets of laser cleaning processing heads 7 and laser cleaning host systems 8, which are located on both sides of the U rib 1 respectively. The laser cleaning processing head 7 is installed on a movable bracket, and the position is adjustable so as to perform laser positioning and focusing before laser cleaning. A laser profile scanner 9 is installed behind the laser cleaning processing head 7, which is used to perform segmented profile sampling on the U rib 1 that has completed laser cleaning, and output the surface geometric features such as roughness and three-dimensional model of the laser-cleaned surface through profile scanning.

[0029] The master control host 10 is connected to the laser cleaning host system 8, the ground rail motion control system and the laser profile scanner 9, and is responsible for collecting information such as the U-rib 1 material number, laser cleaning power, laser cleaning speed, and surface geometric characteristics after cleaning, and archiving each set of data to form a U-rib laser cleaning database.

[0030] Laser cleaning uses a continuous fiber laser with a laser wavelength of 1070-1080nm. Focus state cleaning is used during cleaning, and the laser is converted into a line laser through a galvanometer. The line width is about 40mm, and the cleaning laser power is controlled in the range of 2000-3000W; the laser cleaning speed is 30-50mm / s, and the number of cleanings is 1-3 times. The surface roughness after laser cleaning needs to be controlled within the range of 5.5-7.5μm, which is used to effectively remove surface contaminants and control the reflectivity during laser tracking. If the roughness is too large, the laser power can be appropriately increased, the cleaning speed can be reduced, or the number of cleanings can be increased.

[0031] The surface automated pretreatment method of the present invention for improving the laser visual tracking accuracy of welds is used to cooperate with the laser visual tracking during the single-sided gas shielded welding process between the U-rib and the bridge deck. The single-sided gas shielded welding system between the U-rib and the bridge deck adopts a ship position welding with the bridge deck inclined at 30°. The bridge deck and the U-rib are positioned by spot welding and fixed on the ship position welding bracket. The front end of the welding gun is equipped with a laser visual tracking sensor. Specifically, it includes the following steps:

[0032] Step 1: Grab the U-rib that needs surface pretreatment from the loading area, place it on the transmission roller of the U-rib conveying bracket, and position it through the pneumatic clamp system of the conveying bracket;

[0033] Step 2: Adjust the slide rail mechanism connected to the U-rib conveying drive wheel so that the drive wheel presses the two sides of the U-rib respectively;

[0034] Step 3: Set the linear speed of the driving wheel to 200 mm / s, then start the driving wheel rotation motor, and pause when the front end of the U rib is transported to the position allowed by the laser cleaning processing head;

[0035] Step 3: Set the cleaning laser power to 3000-5000W, the scanning waveform to a horizontal straight line, the line width to 40mm, and adjust the position of the laser cleaning processing head to achieve the focus of the cleaning laser;

[0036] Step 4: The driving wheel is rotated at a linear speed of 30 to 50 mm / s, and laser cleaning is started at the same time, and U-rib laser cleaning is started at a laser power of 3000 to 5000 W and a cleaning speed of 30 to 50 mm / s;

[0037] Step 5: When the cleaned U-rib segment is transported to the laser profile scanner station, start the laser profile scanner to perform segmented 3D profile measurement of the U-rib laser part, save the 3D profile data and roughness data, and set the segmented measurement interval length according to actual needs, which can be selected to be 1 to 3 meters per detection;

[0038] Step 6: If the surface roughness after laser cleaning is within the range of 5.5-7.5 μm, the U-rib will be transported to the unloading area by the grabbing system after the entire U-rib is cleaned for temporary storage for later laser tracking welding; if the roughness is too large, the laser power can be appropriately increased, the cleaning speed can be reduced, or the number of cleaning times can be increased;

[0039] Step 7: Save the information such as U-rib material number, laser cleaning power, laser cleaning speed, and surface geometric features after cleaning through the master control host, and archive these data to the U-rib laser cleaning database;

[0040] Step 8: After the cleaning, the U-rib is subjected to single-sided gas shielded welding at the ship’s inclination angle of 30°. The metal powder cored welding wire T492T1-0C1AUH5 with a diameter of 1.4mm is selected, the dry extension is 15mm, the wire feeding speed is about 9.5m / min, the swing width is 2mm, the welding current is about 280A, the welding gun angle is about 40°, and the laser tracking system is used in the welding process;

[0041] Step 9: After welding is completed, the segmented weld deviation statistics are performed. The part where the penetration rate is less than 80% and the center line of the deposited weld is obviously misaligned is regarded as weld deviation.

[0042] Through the above implementation steps, the Q345qD material U rib was laser cleaned before welding and laser tracking welding was performed. Figure 2 The figures are the statistical graphs of surface roughness after laser cleaning for 1, 2, and 3 times, respectively. (a) is the statistical graph of surface roughness after laser cleaning for 1 time; (b) is the statistical graph of surface roughness after laser cleaning for 2 times; (c) is the statistical graph of surface roughness after laser cleaning for 3 times; Figure 3 The surface morphology after 1, 2, and 3 laser cleanings were taken by scanning electron microscope. (a) is the surface morphology after 1 laser cleaning; (b) is the surface morphology after 1 laser cleaning; (c) is the surface morphology after 1 laser cleaning. It can be seen that the surface roughness is within the range of 5.5 to 7.5 μm after 3 laser cleanings. After 3 laser cleanings, laser tracking welding is performed, and the laser tracking accuracy is greatly improved. Figure 4 The figure is a statistical diagram of the welding offset of the U-rib processed by traditional mechanical grinding and the U-rib processed by the method of the present invention under the same welding process. It can be seen that the welding offset of the U-rib processed by traditional mechanical grinding is about 7%, while the welding offset of the U-rib processed by the method of the present invention is controlled at about 0.5%.

Claims

1. A surface automatic pretreatment device for improving the accuracy of laser visual tracking of welds, characterized in that: It includes a U-rib and a laser cleaning device. The bottom of the U-rib is placed on a supporting mechanism. A transmission mechanism is provided on the top of the U-rib. The bottom of the transmission mechanism is connected to a U-rib conveying driving wheel. The U-rib conveying driving wheel is respectively connected to both sides of the U-rib for transmission. The laser cleaning device includes a laser cleaning processing head. The laser cleaning processing heads are respectively arranged on both sides of the U-rib. One of the laser cleaning processing heads is provided with a laser contour scanner on the side away from the U-rib.

2. According to claim 1, a surface automated pretreatment device for improving the accuracy of laser visual tracking of welds is characterized in that: The support mechanism comprises a U-rib conveying bracket, which is arranged on both sides of the U-rib, and a plurality of U-rib transmission rollers are connected between the U-rib conveying brackets on both sides.

3. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 2 is characterized in that: A pneumatic clamp is provided on the U-rib conveying bracket.

4. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 3 is characterized in that: The surface of the U-rib transmission roller is provided with U-ribs.

5. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 1 is characterized in that: The transmission mechanism comprises a walking gantry, which is installed on a ground rail and a U-rib conveying driving wheel is connected to the bottom of the walking gantry.

6. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 5 is characterized in that: The U-rib conveying driving wheel is installed on the walking gantry through a linear slide rail and a connecting rod.

7. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 1 is characterized in that: The laser cleaning processing head is connected to the laser cleaning host system.

8. The surface automated pretreatment device for improving the laser visual tracking accuracy of welds according to claim 7, characterized in that: The laser cleaning processing head is installed on a movable bracket.

9. The surface automated pretreatment device for improving the laser visual tracking accuracy of weld seams according to claim 7, characterized in that: The laser cleaning host system and the laser profile scanner are connected to the master control host.

10. A pretreatment method based on the surface automated pretreatment device for improving the laser visual tracking accuracy of weld seams according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Place the U-rib that needs surface pretreatment on the transmission roller of the U-rib conveying bracket and position it through the pneumatic clamp system of the conveying bracket; Step 2: Adjust the slide rail mechanism connected to the U-rib conveying driving wheel so that the U-rib conveying driving wheel presses the two sides of the U-rib respectively; Step 3: Pause when the front end of the U rib is transported to the position allowed by the laser cleaning processing head; Step 4: Set the cleaning laser power to 3000-5000W, adjust the position of the laser cleaning processing head, and focus the cleaning laser; set the driving wheel rotation linear speed to 30-50mm / s, and start the laser cleaning at the same time, starting the U-rib laser cleaning with a laser power of 3000-5000W and a cleaning speed of 30-50mm / s; Step 5: When the cleaned U-rib segment is transported to the laser profile scanner station, the laser profile scanner is started to perform segmented three-dimensional profile measurement of the U-rib laser part, and the three-dimensional profile data and roughness data are saved; Step 6: If the surface roughness after laser cleaning is within the range of 5.5-7.5 μm, the U-rib will be transported to the unloading area for temporary storage after the entire U-rib is cleaned for later laser tracking welding; if the roughness is too large, the laser power can be increased, the cleaning speed can be reduced, or the number of cleaning times can be increased; Step 7: The cleaned U-rib is subjected to single-sided gas shielded welding at the ship position, and the laser tracking system is used in the welding process; Step 8: After welding is completed, perform segmented welding deviation statistics.

Images