Vision-based bonding wire tracking method

Abstract

During implementation, connected plates to be welded are fixed to a rotating table through a suction cup, then an area light source is turned on, the rotating table is controlled by a control device to rotate by a circle, a CCD photosensitive element in a groove receives an electric signal excited by light penetrating through a weld joint in the period, and the weld joint is tracked through the CCD photosensitive element. When the welding gun assembly is used for welding a plate, the light is transmitted to the control device, the control device draws a curve according to the change of the maximum illumination position along with time in a period, the single-shaft driving mechanism is controlled to drive the welding gun assembly to weld the plate according to the curve in the welding process, and low-cost intelligent welding is achieved.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to a welding line tracking method based on vision. Background Art

[0002] Welding occupies an important position in modern industrial production. With the rapid development of science and technology, the automation and intelligence of welding has become an important research direction in the field of welding. Modern production has also put forward higher requirements for welding quality and efficiency. At present, most welding is performed by robots or workbenches according to pre-set trajectories. This method depends on the material of the workpiece and the clamping of the weldment before welding. It is also time-consuming and laborious to calculate welds with complex trajectories. Since robots and workbenches themselves only have execution capabilities, they cannot judge and correct according to changes in the surrounding environment. Therefore, in reality, workpiece assembly errors and changes in weld position and size caused by thermal deformation during welding often cause the welding gun movement trajectory to deviate from the actual weld, resulting in a decrease in welding quality or even failure. Therefore, it is very necessary to use appropriate weld automatic tracking technology for correction.

[0003] The automatic tracking technology of weld seams first needs to use certain sensing technologies to obtain the position of the weld seams relative to the welding gun. Common weld seam identification sensors mainly include: arc sensors, contact sensors, ultrasonic sensors and visual sensors. Among them, the contact sensor has a simple structure and is not affected by arc smoke, but it needs to use different probes for different forms of weld seams, and it is easy to deform due to large wear; the arc sensor has no mechanical wear, but it is difficult to establish an accurate model of arc length and current changes, which brings difficulties to weld seam detection; ultrasonic sensors are an advanced weld seam identification sensor, which is made based on the principle of ultrasonic waves propagating in metals to produce reflections. It has good real-time performance in weld seam tracking, but because it must be close to the surface of the weldment, it is inevitably limited by the welding method and weldment size. In addition, factors such as sound propagation time must be considered, and there are high requirements for the weldment surface, so the application range of ultrasonic sensors is limited.

[0004] Existing welding equipment that can track welds, such as a welding system and a weld tracking method described in application number CN201811405951.1, involves a mechanism for clamping a welding gun, which requires multi-axis drive to align the welding gun with the weld. The cost of a robotic arm or a multi-axis transmission module that realizes multi-axis transmission is also high, which is not conducive to cost control. Summary of the invention

[0005] In order to reduce manufacturing costs, a single-axis drive is used for weld tracking. The present invention proposes a vision-based weld tracking method, comprising the following steps: S1. Fix the partially connected plates to be welded on the rotating mechanism; S2. A light source emitting upward is provided as a backlight from below one side of the rotating mechanism; S3. A linearly movable welding device is provided in the area above the light source, and a groove in the same direction as the track is provided on the movable track of the welding device, and a linearly distributed CCD photosensitive element is provided on the top of the groove; S4. The CCD photosensitive elements are numbered in sequence and connected to the control device; S5. With the light source turned on, the control device controls the rotating mechanism to rotate for the first circle, and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment evenly divided within one circle, that is, the specific position of the weld on the moving track at each moment is known, and a time-position change curve is prepared; S6. The position information of the number conversion is translated into the moving distance of the welding device and the speed information of each section. While controlling the rotating mechanism to rotate for the second circle, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thereby completing the weld tracking.

[0006] Preferably, in step S5, the control device controls one cycle of the rotating mechanism to be divided into n equal parts, and records the number of the CCD photosensitive element with the largest transmitted electrical signal at the acquisition moments t1, t2, ..., tn, with the interval between adjacent moments being less than 0.5s.

[0007] Preferably, in step S6, adjacent collection moments in the drawn curve are connected by a smooth curve, and the control device controls the moving speed of the welding device in each adjacent collection moment to be positively correlated with the tangent slope of the curve at that moment.

[0008] In addition, a welding device for supporting the above-mentioned tracking method is proposed, and its structure includes: an operating table, a rotating table is arranged on the operating table, and a suction cup is arranged on the top of the rotating table; a surface light source is arranged on the right side of the rotating table on the operating table, and an L-shaped mounting frame is arranged on the right side of the operating table, and the upper beam of the mounting frame extends to the top of the suction cup; a single-axis driving mechanism that can move linearly along the upper beam direction is arranged on the top of the upper beam, and a welding gun assembly is installed at the lower part of the single-axis driving mechanism; left and right grooves are arranged on the lower surface of the upper beam, and linearly distributed CCD photosensitive elements are arranged on the top of the groove; and a control device is also included, which receives feedback from the CCD photosensitive element and controls the operation of the rotating table, the single-axis driving mechanism, and the welding gun assembly.

[0009] Preferably, the single-axis drive mechanism includes: a drive motor arranged at the right end of the upper beam, the rotating shaft of the drive motor drives the ball screw to rotate, and also includes a slider, the upper portion of the slider is provided with a through hole, one end of the through hole is equipped with a screw nut, the ball screw passes through the through hole, and the screw nut is sleeved on the outside of the ball screw to enable the drive motor to drive the slider to perform linear motion.

[0010] Preferably, the welding gun assembly comprises: a clamping mechanism and a welding gun; the welding gun clamping mechanism is fixed to the bottom of the slider, the fixing point is below the upper beam, and the clamping mechanism clamps the welding gun.

[0011] Preferably, the rotating table comprises: a rotating shaft, a platform is fixed on the upper part of the rotating shaft, and the lower part is connected to a driving motor to be driven to rotate; the above-mentioned driving motors are all servo motors.

[0012] Preferably, the surface light source is an LED lamp; and the control device is an industrial computer.

[0013] The present invention is applicable to partially connected plates, which may be damaged plates repaired by welding, or two complete plates fixed by partial welding. When in use, the connected plates to be welded are fixed on a rotating table by suction cups, and then the surface light source is turned on. The rotating table is controlled by a control device to rotate one circle. During this cycle, the CCD photosensitive element in the groove receives an electrical signal excited by light transmitted through the weld, and transmits it to the control device. The control device plots the change of the maximum illumination position over time in a cycle into a curve, and according to the curve, controls the single-axis drive mechanism to drive the welding gun assembly to weld the plates during the welding process, thereby realizing low-cost intelligent welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a three-dimensional diagram of the welding device of the present invention.

[0016] Figure 2 It is a top view of the welding device of the present invention.

[0017] Figure 3 for Figure 2 AA section view.

[0018] In the figure: 1. operating table; 2. rotating table; 3. suction cup; 4. surface light source; 5. mounting frame; 6. driving motor; 7. slider; 8. welding gun assembly; 9. groove; 10. CCD photosensitive element. DETAILED DESCRIPTION

[0019] The various devices selected in this application (components whose specific structures are not described) are all universal standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0020] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0022] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0023] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0024] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. Example

[0025] A vision-based welding wire tracking method includes the following steps: S1. Fixing some of the connected plates to be welded on the rotating mechanism to fix the plates and drive the plates to rotate; S2. A light source emitting upward is provided at the bottom of one side of the rotating mechanism as a backlight, and the backlight is provided to allow the backlight to penetrate the weld and enter the upper area of ​​the plate; S3. A linearly movable welding device is arranged in the area above the light source, and a groove in the same direction as the track is arranged on the movable track of the welding device, and a linearly distributed CCD photosensitive element is arranged on the top of the groove. The weld is directly below the groove, that is, in the uniaxial coordinate with the groove as the starting point. There is only one intersection point at any time, and the backlight is captured from this point to the CCD photosensitive element, thereby stimulating it to generate an electrical signal; S4. The CCD photosensitive elements are numbered in sequence and connected to the control device. The numbering is performed based on the position of the CCD photosensitive elements in the single-axis coordinate system, so that the control device can accurately receive which CCD photosensitive element the weld is facing at each acquisition moment. The judgment basis is the CCD photosensitive element that generates the largest electrical signal. S5. With the light source turned on, the control device controls the rotating mechanism to rotate for the first circle, and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment evenly divided within one circle, that is, the specific position of the weld on the moving track at each moment is known, and a time-position change curve is prepared; S6. The position information of the number conversion is translated into the moving distance of the welding device and the speed information of each section. While controlling the rotating mechanism to rotate for the second circle, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thereby completing the weld tracking.

[0026] More specifically, in step S5, the control device controls the rotating mechanism to rotate in one cycle and divides it into n equal parts. At the acquisition moments t1, t2, ..., tn, the number of the CCD photosensitive element that transmits the largest electrical signal is recorded. The interval between adjacent moments is less than 0.5s. The smaller the time interval, the more accurate the tracking.

[0027] More specifically, in step S6, adjacent collection moments in the drawn curve are connected by a smooth curve, and the control device controls the moving speed of the welding device in each adjacent collection moment to be positively correlated with the tangent slope of the curve at that moment. Example

[0028] like Figure 1-Figure 3 As shown, the positional relationship between the left and right in this example is Figure 2 or Figure 3The left and right sides of the welding device are used to support the above-mentioned vision-based welding line tracking method. Its structure includes: an operating table 1, a rotating table 2 is arranged on the operating table 1, and a suction cup 3 is arranged on the top of the rotating table 2; on the operating table 1, a surface light source 4 is arranged on the right side of the rotating table 2, and an L-shaped mounting frame 5 is arranged on the right side of the operating table 1. The L-shape is set to minimize the material consumption as much as possible, and the upper beam of the mounting frame 5 extends to the top of the suction cup 3; the top of the upper beam is provided with a single-axis driving mechanism that can move linearly along the upper beam direction, and the lower part of the single-axis driving mechanism is provided with a welding gun assembly 8; the lower surface of the upper beam is provided with left and right grooves 9, and the top of the groove 9 is provided with a linearly distributed CCD photosensitive element 10; it also includes a control device, the control device receives feedback from the CCD photosensitive element 10 and controls the operation of the rotating table 2, the single-axis driving mechanism, and the welding gun assembly 8.

[0029] More specifically, the single-axis drive mechanism includes: a drive motor 6 arranged at the right end of the upper beam, the rotating shaft of the drive motor 6 drives the ball screw to rotate, and also includes a slider 7, a through hole is provided on the upper part of the slider 7, a screw nut is installed at one end of the through hole, the ball screw passes through the through hole, and the screw nut is sleeved on the outside of the ball screw to realize the drive motor 6 to drive the slider 7 to make linear motion.

[0030] More specifically, the welding gun assembly 8 includes: a clamping mechanism and a welding gun; the welding gun clamping mechanism is fixed to the bottom of the slider 7, and the fixing point is below the upper beam. The clamping mechanism clamps the welding gun. The welding gun clamping mechanism is a prior art, which at least includes a clamping function, and a vertically movable structure can be added according to actual conditions.

[0031] More specifically, the rotating table 2 includes: a rotating shaft, a platform is fixed on the upper part of the rotating shaft, and the lower part is connected to the driving motor 6 and driven to rotate by it; the above-mentioned driving motor 6 is a servo motor, and the closed-loop controlled power source can accurately meet the requirements of this case.

[0032] More specifically, the surface light source 4 is an LED lamp; the control device is an industrial computer, which can better implement the design concept of the present invention.

[0033] The present invention is applicable to partially connected plates, which may be damaged plates repaired by welding, or two complete plates fixed by partial welding. When in use, the connected plates to be welded are fixed on a rotating table by suction cups, and then the surface light source is turned on. The rotating table is controlled by a control device to rotate one circle. During this cycle, the CCD photosensitive element in the groove receives an electrical signal excited by light transmitted through the weld, and transmits it to the control device. The control device plots the change of the maximum illumination position over time in a cycle into a curve, and according to the curve, controls the single-axis drive mechanism to drive the welding gun assembly to weld the plates during the welding process, thereby realizing low-cost intelligent welding.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vision-based welding wire tracking method, characterized in that: The steps include: S1. Fix the partially connected plates to be welded on the rotating mechanism; S2. A light source emitting upward is provided as a backlight from below one side of the rotating mechanism; S3. A linearly movable welding device is provided in the area above the light source, and a groove in the same direction as the track is provided on the movable track of the welding device, and a linearly distributed CCD photosensitive element is provided on the top of the groove; S4. The CCD photosensitive elements are numbered in sequence and connected to the control device; S5. With the light source turned on, the control device controls the rotating mechanism to rotate for the first circle, and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment evenly divided within one circle, that is, the specific position of the weld on the moving track at each moment is known, and a time-position change curve is prepared; S6. The position information of the number conversion is translated into the moving distance of the welding device and the speed information of each section. While controlling the rotating mechanism to rotate for the second circle, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thereby completing the weld tracking.

2. The vision-based wire tracking method according to claim 1, characterized in that: In step S5, the control device controls the rotating mechanism to rotate in one cycle, which is divided into n equal parts, and records the number of the CCD photosensitive element with the largest transmitted electrical signal at the acquisition moments t1, t2, ..., tn, with the interval between adjacent moments being less than 0.5s.

3. The vision-based welding wire tracking method according to claim 2, characterized in that: In step S6, adjacent collection moments in the drawn curve are connected by a smooth curve, and the control device controls the moving speed of the welding device in each adjacent collection moment to be positively correlated with the tangent slope of the curve at that moment.

4. A welding device based on the vision-based welding wire tracking method according to claim 1, characterized in that: include: An operating table is provided on the operating table, and a suction cup is provided on the top of the rotating table; a surface light source is provided on the right side of the rotating table, and an L-shaped mounting frame is provided on the right side of the operating table, and the upper beam of the mounting frame extends to the top of the suction cup; a single-axis driving mechanism that can move linearly along the upper beam direction is provided on the top of the upper beam, and a welding gun assembly is installed at the lower part of the single-axis driving mechanism; left-right grooves are provided on the lower surface of the upper beam, and linearly distributed CCD photosensitive elements are provided on the top of the grooves; and a control device is also included, which receives feedback from the CCD photosensitive element and controls the operation of the rotating table, the single-axis driving mechanism, and the welding gun assembly.

5. The welding equipment according to claim 4, characterized in that: The single-axis driving mechanism includes: a driving motor arranged at the right end of the upper beam, the rotating shaft of the driving motor drives the ball screw to rotate, and also includes a slider, a through hole is provided on the upper part of the slider, a screw nut is installed at one end of the through hole, the ball screw passes through the through hole, and the screw nut is sleeved on the outside of the ball screw to realize the driving motor driving the slider to make linear motion.

6. The welding equipment according to claim 5, characterized in that: The welding gun assembly comprises: a clamping mechanism and a welding gun; the welding gun clamping mechanism is fixed to the bottom of the slide block, the fixing point is below the upper beam, and the clamping mechanism clamps the welding gun.

7. The welding equipment according to claim 6, characterized in that: The rotating platform comprises a rotating shaft, a platform is fixed on the upper part of the rotating shaft, and the lower part is connected to a driving motor to be driven to rotate; the driving motors are all servo motors.

8. The welding equipment according to claim 7, characterized in that: The surface light source is an LED lamp; the control device is an industrial computer.

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