Portable dexterous robot steel bridge deck welding seam tracking method and system

Abstract

The invention discloses a steel bridge deck welding seam tracking method and system through a portable dexterous robot, and the method comprises the following steps: building a welding data enabling the portable dexterous robot to obtain the corresponding relation between the welding seam morphology of steel bridge deck welding and the welding parameters and the welding gun posture through an electric arc tracking mode and a laser tracking mode; establishing a database; the three-dimensional coordinates of the workpiece are obtained through a visual system before welding, welding seam feature points are taken out, and welding is conducted based on a welding database. The method comprises the following steps of: obtaining a corresponding relation among weld seam morphology, welding parameters and welding gun postures on the basis of an electric arc tracking mode and a laser tracking mode, and establishing a database; before welding, three-dimensional coordinates of a workpiece are obtained through a visual system, weld joint feature points are taken out, welding is carried out based on a welding database, data support is provided for obtaining the steel bridge deck with good forming and high fatigue performance, the method overcomes many defects in the prior art, and the application range of steel bridge deck welding is expanded.

Description

Technical Field

[0001] The invention relates to a weld tracking method and system, and in particular to a portable dexterous robot steel bridge deck weld tracking method and system. Background Art

[0002] Orthotropic steel bridge deck is a main unit commonly used in the domestic bridge manufacturing industry. It has been widely used in large bridge buildings such as the Changtai Yangtze River Bridge due to its low mass density, large load-bearing capacity, and wide range of application scenarios. With the rapid development of modernization, the use of automobiles has increased year by year, and some steel bridge decks have experienced fatigue problems during their service. As the core component of the bridge structure, the welding process of the U-rib and the panel and the welding process of the diaphragm and the panel play the most important role in the welding process of the overall bridge and are the key parts that affect the fatigue resistance of the steel bridge deck.

[0003] The thermal deformation generated during the welding process of steel bridge decks continues to accumulate, which may cause the weld position to deviate from the predetermined welding track. The traditional teaching positioning method can only complete welding according to the predetermined welding route and cannot correct the position deviation that occurs during the welding process, resulting in the quality and accuracy of the weld failing to meet production requirements. In addition, for a large number of welds, the efficiency of using robot teaching welding is low. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to propose a portable dexterous robot steel bridge deck weld tracking method and system to improve the low welding efficiency of the flat corner welding between the panel and the diaphragm and the vertical corner welding between the U rib and the diaphragm, as well as the fatigue strength of the steel bridge deck.

[0005] Technical solution: The present invention comprises the following steps:

[0006] S1. Build welding database: The portable robot uses arc tracking and laser tracking to obtain the corresponding relationship between the weld morphology of steel bridge deck welding and welding parameters and welding gun posture, and establishes a database;

[0007] S2. Weld identification and welding: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

[0008] The arc tracking collects the flat fillet welding data of the panel and the diaphragm, and during the welding process, mainly ensures that there are no defects inside the weld, the weld has a smooth transition, and the weld joint has fatigue resistance.

[0009] The flat fillet welding depth prediction model of the panel and the diaphragm obtained by the arc tracking is: h=2.724*d1+1.777*d2-40.098, wherein h is the excess height, d1 is the diaphragm weld foot, and d2 is the panel weld foot or the U-rib weld foot.

[0010] The laser tracking collects the flat angle welding data between the panel and the diaphragm and the vertical angle welding data between the U rib and the diaphragm, and during the welding process, mainly ensures that there are no defects inside the weld, the weld has a smooth transition, and the weld joint has fatigue resistance.

[0011] The prediction model of the vertical fillet weld penetration depth between the U rib and the diaphragm obtained by laser tracking is: h=-21.074*d1-5.752*d2+295.829; wherein h is the excess height, d1 is the diaphragm weld foot, and d2 is the panel weld foot or the U rib weld foot.

[0012] The front end of the welding gun of the portable robot is equipped with a robot vision system.

[0013] The visual system includes a camera, a lens, a light source, an image acquisition card, and a visual processor.

[0014] The steel bridge deck is formed by connecting U-ribs, decks and diaphragms.

[0015] The steel bridge deck welding includes flat fillet welding between the deck and the diaphragm, and vertical fillet welding between the U rib and the diaphragm.

[0016] A portable dexterous robot steel bridge deck weld tracking system, comprising:

[0017] Welding database building module: The portable dexterous robot uses arc tracking and laser tracking to obtain the corresponding relationship between the weld morphology of steel bridge deck welding and welding parameters and welding gun posture, and establishes a database;

[0018] Weld seam recognition module: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

[0019] Beneficial effects: The present invention adopts arc tracking and laser tracking to realize the welding of steel bridge decks. The correspondence between weld morphology and welding parameters and welding gun posture is obtained based on the arc tracking and laser tracking, and a database is established. Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are taken out, and welding is performed based on the welding database, so as to provide data support for obtaining steel bridge decks with good forming and high fatigue performance. This method overcomes many shortcomings of the prior art and expands the application scope of steel bridge deck welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of typical dimensions of steel bridge deck welded joints. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] The portable dexterous robot steel bridge deck weld tracking method of the present invention is based on arc tracking and laser tracking weld formation control technology, and is equipped with a weld tracking technology of a visual system. The corresponding relationship between the weld morphology and the welding parameters and the welding gun posture is obtained based on arc tracking and laser tracking, and a database is established; before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are taken out, and welding is performed based on the welding database. Specifically, the following steps are included:

[0023] S1. Build welding database: The portable dexterous robot uses arc tracking and laser tracking to obtain the correspondence between the weld morphology of steel bridge deck welding and welding parameters and welding gun posture, and establishes a database.

[0024] The portable dexterous robot is a six-axis robot that weighs less than 25kg and can be moved directly. The portable dexterous robot uses arc tracking and laser tracking to realize the welding of steel bridge decks. Based on the arc tracking and laser tracking methods, the correspondence between the weld morphology and welding parameters and welding gun posture is obtained, and a database is established.

[0025] The arc tracking flat welds are all convex welds with similar shapes. The difference between the U-rib weld feet and the panel weld feet is small, the weld area is large, and the formation is good. The vertical weld has a large weld penetration and an irregular weld shape. The base material is not fully melted at the weld toes on both sides, resulting in the inability to effectively fill the weld wire and poor formation. The positioning accuracy of arc tracking in the flat fillet weld is high, while the error in the vertical fillet weld is large, and there is an over-welding deviation. Arc tracking should be avoided as much as possible during vertical fillet welding.

[0026] The flat fillet weld has clear and regular lines, a smooth surface, metallic luster, and the width and thickness of the weld are basically consistent without obvious defects. The transition at the corner is relatively smooth, without large weld nodules, and fatigue cracks are not easy to occur.

[0027] Arc tracking mainly collects data on flat angle welds between panels and diaphragms, while laser tracking collects data on flat angle welds between panels and diaphragms and vertical angle welds between U-ribs and diaphragms; during welding, the main tasks are to ensure that there are no defects inside the weld, that the weld transition is smooth, and that the weld joint is fatigue-resistant. During the welding of steel bridge decks, weld tracking technology can ensure that the welding process is stable and control the position of the welding gun so that the set welding wire is aligned 2mm from the root of the weld.

[0028] The front end of the welding gun of the portable dexterous robot is equipped with a robot vision system, which includes a camera, lens, light source, image acquisition card, and vision processor.

[0029] The steel bridge deck is connected by U ribs, panels and diaphragms; the steel bridge deck welding mainly includes flat fillet welding between panels and diaphragms, and vertical fillet welding between U ribs and diaphragms. The prediction model of flat fillet welding depth between panels and diaphragms based on arc tracking is: h = 2.724*d1+1.777*d2-40.098; the prediction model of vertical fillet welding depth between U ribs and diaphragms based on laser tracking is: h = -21.074*d1-5.752*d2+295.829; where h is the residual height, such as Figure 1 shown.

[0030] S2. Weld identification and welding: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

[0031] The present invention also provides a portable dexterous robot steel bridge deck weld tracking system, comprising:

[0032] Welding database building module: The portable dexterous robot uses arc tracking and laser tracking to obtain the correspondence between the weld morphology of steel bridge deck welding and the welding parameters and welding gun posture, and establishes a database.

[0033] The portable dexterous robot is a six-axis robot that weighs less than 25kg and can be moved directly. The portable dexterous robot uses arc tracking and laser tracking to realize the welding of steel bridge decks. Based on the arc tracking and laser tracking methods, the correspondence between the weld morphology and welding parameters and welding gun posture is obtained, and a database is established.

[0034] Arc tracking mainly collects data on flat angle welds between panels and diaphragms, while laser tracking collects data on flat angle welds between panels and diaphragms and vertical angle welds between U-ribs and diaphragms; during welding, the main tasks are to ensure that there are no defects inside the weld, that the weld transition is smooth, and that the weld joint is fatigue-resistant. During the welding of steel bridge decks, weld tracking technology can ensure that the welding process is stable and control the position of the welding gun so that the set welding wire is aligned 2mm from the root of the weld.

[0035] The front end of the welding gun of the portable dexterous robot is equipped with a robot vision system, which includes a camera, lens, light source, image acquisition card, and vision processor.

[0036] The steel bridge deck is connected by U ribs, panels and diaphragms; the steel bridge deck welding mainly includes the flat fillet welding between the panel and the diaphragm, and the vertical fillet welding between the U rib and the diaphragm. The prediction model of the flat fillet welding depth between the panel and the diaphragm based on arc tracking is: h = 2.724*d1+1.777*d2-40.098; the prediction model of the vertical fillet welding depth between the U rib and the diaphragm based on laser tracking is: h = -21.074*d1-5.752*d2+295.829; where h is the excess height, d1 is the diaphragm weld foot; d2 is the panel weld foot or U rib weld foot.

[0037] Weld seam recognition module: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

[0038] Due to the dimensional error of the steel bridge deck itself and the deformation caused by welding thermal stress, there will be a difference between the actual weld trajectory and the programmed trajectory, and the large weld size deviation will cause low fatigue performance and other problems. The present invention builds a database of the influence of welding parameters and welding gun posture on weld formation, and realizes weld tracking based on a visual system to provide data support for obtaining a steel bridge deck with good formation and high fatigue performance. This method overcomes many shortcomings of the prior art and expands the application scope of steel bridge deck welding.

[0039] Example

[0040] The portable dexterous robot steel bridge deck weld tracking method of this embodiment comprises the following steps:

[0041] First, Q370qE for railway bridges was selected as the test material. The panel, U rib and diaphragm were all made of the same material. The thickness of the U rib was 8mm, the thickness of the panel was 20mm, and the thickness of the diaphragm was 18mm. The welding machine used was the NBC-series inverter welding machine, 1.6mm diameter solid welding wire was used as the filling material, and CO2 was used as the protective gas.

[0042] The welding current of the vertical welding part at the connection between the cross partition and the U rib is 150-160A, the welding voltage is 16±1V, the wire feeding speed is 5m / min, the welding speed is 11.9cm / min, the wire swing frequency is 50Hz, and the dry extension length is set to 15mm; the welding parameters of the flat welding part and the vertical welding part at the connection between the connecting plate and the panel are different. The welding current is selected to be 230-240A, the welding voltage is 23±1V, the wire feeding speed is 10.5m / min, the welding speed is 26.0cm / min, and the dry extension length is set to 25mm; the welding from the flat fillet welding to the vertical fillet welding part must be carried out continuously, and the welding cannot be interrupted to adjust the test parameters in the middle.

[0043] The arc tracking flat welds are all convex welds with similar shapes. The difference between the U-rib weld feet and the panel weld feet is small, the weld area is large, and the formation is good. The vertical weld has a large weld penetration and an irregular weld shape. The base material is not fully melted at the weld toes on both sides, resulting in the inability to effectively fill the weld wire and poor formation. The positioning accuracy of arc tracking in the flat fillet weld is high, while the error in the vertical fillet weld is large, and there is an over-welding deviation. Arc tracking should be avoided as much as possible during vertical fillet welding.

[0044] The flat fillet weld has clear and regular lines, a smooth surface, metallic luster, and the width and thickness of the weld are basically consistent without obvious defects. The transition at the corner is relatively smooth, without large weld nodules, and fatigue cracks are not easy to occur.

[0045] The corresponding relationship between weld morphology and welding parameters is obtained based on arc tracking and laser tracking. Figure 1 As shown in Table 1, the flat fillet welding depth prediction model of the panel and the diaphragm is obtained based on arc tracking: h = 2.724*d1+1.777*d2-40.098; the vertical fillet welding depth prediction model of the U rib and the diaphragm is obtained by laser tracking: h = -21.074*d1-5.752*d2+295.829. The front end of the welding gun is equipped with a robot vision system. Before welding, the three-dimensional coordinates of the workpiece are obtained through the vision system, and the weld feature points are taken out. The welding is performed based on the arc tracking and laser tracking welding depth prediction models, and finally a weld with smooth welds and few defects is obtained.

[0046] Table 1 Typical dimensions of flat fillet welds and vertical fillet welds for steel bridge decks

[0047]

Claims

1. A portable dexterous robot steel bridge deck weld tracking method, characterized in that: The following steps are involved: S1. Build welding database: The portable robot uses arc tracking and laser tracking to obtain the corresponding relationship between the weld morphology of steel bridge deck welding and welding parameters and welding gun posture, and establishes a database; S2. Weld identification and welding: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

2. A portable dexterous robot steel bridge deck weld tracking method according to claim 1, characterized in that: The arc tracking collects flat fillet welding data of the panel and the diaphragm.

3. A portable dexterous robot steel bridge deck weld tracking method according to claim 2, characterized in that: The flat fillet welding depth prediction model of the panel and the diaphragm obtained by the arc tracking is: h=2.724*d1+1.777*d2-40.098, wherein h is the excess height, d1 is the diaphragm weld foot, and d2 is the panel weld foot or the U-rib weld foot.

4. The portable dexterous robot steel bridge deck weld tracking method according to claim 1 is characterized in that: The laser tracking collects the flat fillet weld data between the panel and the diaphragm and the vertical fillet weld data between the U rib and the diaphragm.

5. A portable dexterous robot steel bridge deck weld tracking method according to claim 4, characterized in that: The prediction model of the vertical fillet weld penetration depth between the U rib and the diaphragm obtained by laser tracking is: h=-21.074*d1-5.752*d2+295.829; wherein h is the excess height, d1 is the diaphragm weld foot, and d2 is the panel weld foot or the U rib weld foot.

6. The portable dexterous robot steel bridge deck weld tracking method according to claim 1, characterized in that: The front end of the welding gun of the portable robot is equipped with a robot vision system.

7. A portable dexterous robot steel bridge deck weld tracking method according to claim 6, characterized in that: The robot vision system includes a camera, a lens, a light source, an image acquisition card, and a vision processor.

8. The portable dexterous robot steel bridge deck weld tracking method according to claim 1, characterized in that: The steel bridge deck is formed by connecting U-ribs, decks and diaphragms.

9. A portable dexterous robot steel bridge deck weld tracking method according to claim 8, characterized in that: The steel bridge deck welding includes flat fillet welding between the deck and the diaphragm, and vertical fillet welding between the U rib and the diaphragm.

10. A portable dexterous robot steel bridge deck weld tracking system, characterized in that: include: Welding database building module: The portable dexterous robot uses arc tracking and laser tracking to obtain the corresponding relationship between the weld morphology of steel bridge deck welding and welding parameters and welding gun posture, and establishes a database; Weld seam recognition module: Before welding, the three-dimensional coordinates of the workpiece are obtained through the visual system, the weld feature points are extracted, and welding is performed based on the welding database.

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