A vision-based wire bonding tracking method

Abstract

The application discloses a visual-based wire welding tracking method. In the implementation, the connected plate to be welded is fixed on a rotating table through a suction cup, and a surface light source is turned on. The rotating table is controlled to rotate by a control device for one circle. In the period, the CCD photosensitive element in the groove receives the light excited by the welding seam and transmits the electric signal to the control device. The control device draws the curve of the maximum light position in one period changing with time, and controls the single-axis driving mechanism to drive the welding gun assembly to weld the plate according to the curve in the welding process, so that the low-cost intelligent welding is realized.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more particularly to a vision-based weld wire tracking method. Background Technology

[0002] Welding plays a vital role in modern industrial production. With the rapid development of technology, the automation and intelligentization of welding have become important research directions in the field. Modern production also places higher demands on welding quality and efficiency. Currently, most welding is performed by robots or workbenches following pre-set trajectories. This method relies on the workpiece material and the clamping of the workpiece before welding, and calculating complex weld trajectories is time-consuming and labor-intensive. Since robots and workbenches only have execution capabilities and cannot judge or correct according to changes in the surrounding environment, in reality, workpiece assembly errors and changes in weld position and size caused by thermal deformation during welding often lead to the welding torch's movement trajectory deviating from the actual weld, resulting in decreased welding quality or even failure. Therefore, it is essential to adopt appropriate automatic weld tracking technology for correction.

[0003] Automatic weld seam tracking technology first requires the use of certain sensing technologies to obtain the position of the weld seam relative to the welding torch. Common weld seam identification sensors mainly include: arc sensors, contact sensors, ultrasonic sensors, and vision sensors. Among them, contact sensors have a simple structure and are not affected by arc fumes, but different probes are required for different types of weld seams, and they are prone to wear and deformation. Arc sensors have no mechanical wear, but it is difficult to establish an accurate model of arc length and current changes, which brings difficulties to weld seam inspection. Ultrasonic sensors are an advanced type of weld seam identification sensor, which is made based on the principle of ultrasonic waves propagating in metal and generating reflections. They have good real-time performance in weld seam tracking, but because they must be close to the surface of the weldment, they are inevitably limited by welding methods and weldment sizes. In addition, factors such as sound propagation time must be considered, and high requirements are placed on the surface of the weldment, so the application range of ultrasonic sensors is limited.

[0004] Existing welding equipment capable of weld seam tracking, such as the welding system and weld seam tracking method described in application number CN201811405951.1, all require multi-axis drive in the mechanism for clamping the welding torch to align the welding torch with the weld seam. The cost of the robotic arm or multi-axis drive module that achieves multi-axis drive is also high, which is not conducive to cost control. Summary of the Invention

[0005] To reduce manufacturing costs, a vision-based weld line tracking method is proposed using single-axis drive for weld seam tracking, comprising the following steps:

[0006] S1. Fix the partially connected plates to be welded onto the rotating mechanism;

[0007] S2. An upward-emitting light source is provided below one side of the rotating mechanism as a backlight;

[0008] S3. A linearly moving welding device is set in the area above the light source, and a groove in the same direction as the track is set on the moving track of the welding device, and a linearly distributed CCD photosensitive element is set at the top of the groove;

[0009] S4. The CCD photosensitive elements are numbered sequentially and connected to the control device;

[0010] S5. With the light source on, the control device controls the rotating mechanism to rotate for the first revolution and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment within one revolution, thus knowing the specific position of the weld on the moving track at each moment and creating a time-position change curve.

[0011] S6. The position information converted by the number is translated into the moving distance and speed information of each segment of the welding device. While controlling the rotating mechanism to rotate for the second time, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thus completing the weld tracking.

[0012] Preferably, in step S5, the rotation of the rotating mechanism controlled by the control device is divided into n equal parts within one cycle, and the number of the CCD photosensitive element that transmits the largest electrical signal is recorded at the acquisition times t1, t2...tn, with the interval between adjacent times being less than 0.5s.

[0013] Preferably, in step S6, adjacent acquisition times in the plotted curve are connected by a smooth curve, and the control device controls the moving speed of the welding device in each adjacent acquisition time to be positively correlated with the slope of the tangent line of the curve at that time.

[0014] Furthermore, a welding device for supporting the aforementioned tracking method is proposed, comprising: an operating table with a rotating platform and a suction cup on top of the rotating platform; a surface light source on the right side of the rotating platform and an L-shaped mounting bracket on the right side of the operating table, the upper beam of which extends above the suction cup; a single-axis drive mechanism that can move linearly along the direction of the upper beam on the top of the upper beam, with a welding torch assembly mounted below the single-axis drive mechanism; a left-right groove on the lower surface of the upper beam, with linearly distributed CCD photosensitive elements at the top of the groove; and a control device that receives feedback from the CCD photosensitive elements and controls the operation of the rotating platform, the single-axis drive mechanism, and the welding torch assembly.

[0015] Preferably, the single-axis drive mechanism includes: a drive motor located at the right end of the upper beam, the drive motor shaft driving the ball screw to rotate, and a slider, the upper part of the slider having a through hole, one end of the through hole being fitted with a screw nut, the ball screw passing through the through hole, and the screw nut being sleeved on the outside of the ball screw, so as to realize that the drive motor drives the slider to perform linear motion.

[0016] Preferably, the welding torch assembly includes: a clamping mechanism and a welding torch; the welding torch clamping mechanism is fixed to the bottom of the slider, the fixing point is located below the upper beam, and the clamping mechanism clamps the welding torch.

[0017] Preferably, the rotary table includes: a rotating shaft, with a platform fixed to the upper part of the rotating shaft and the lower part connected to a drive motor, which drives the rotating shaft to rotate; the drive motors are all servo motors.

[0018] Preferably, the surface light source is an LED lamp; the control device is an industrial computer.

[0019] This invention is applicable to partially connected plates, which can be plates damaged by welding repair, or two complete plates fixed by partial welding. In use, the connected plates to be welded are fixed to a rotating table by suction cups, and then the surface light source is turned on. The control device controls the rotating table to rotate one revolution. During this cycle, the electrical signal excited by the light transmitted through the weld seam received by the CCD photosensitive element in the groove is transmitted to the control device. The control device plots the change of the maximum illumination position over time within one cycle as 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, thus realizing low-cost intelligent welding. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a perspective view of the welding apparatus described in this invention.

[0022] Figure 2 This is a top view of the welding apparatus described in this invention.

[0023] Figure 3 for Figure 2 AA sectional view.

[0024] In the diagram: 1. Operating table; 2. Rotary table; 3. Suction cup; 4. Surface light source; 5. Mounting bracket; 6. Drive motor; 7. Slider; 8. Welding torch assembly; 9. Groove; 10. CCD photosensitive element. Detailed Implementation

[0025] All the devices selected in this application (parts whose specific structures are not specified) are general standard parts or parts known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0026] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0029] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0030] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. Example

[0031] A vision-based wire bonding tracking method includes the following steps:

[0032] S1. Fix some of the connected plates to be welded onto the rotating mechanism to fix the plates and drive them to rotate;

[0033] S2. An upward-emitting light source is set below one side of the rotating mechanism as a backlight. The backlight is set so that the backlight can be transmitted through the weld seam into the area above the plate.

[0034] S3. A linearly moving welding device is set in the area above the light source, and a groove in the same direction as the track is set on the moving track of the welding device. A linearly distributed CCD photosensitive element is set at the top of the groove. The weld is directly below the groove, that is, in the single-axis coordinate with the groove as the starting point. At any time, there is only one intersection point. The backlight is taken into the CCD photosensitive element from this point, thereby exciting it to generate an electrical signal.

[0035] S4. The CCD photosensitive elements are numbered sequentially and connected to the control device. The numbering is based on the position of the CCD photosensitive elements in a single-axis coordinate system, so that the control device can accurately receive which CCD photosensitive element the weld seam is facing at each acquisition moment. The judgment is based on the CCD photosensitive element that generates the largest electrical signal.

[0036] S5. With the light source on, the control device controls the rotating mechanism to rotate for the first revolution and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment within one revolution, thus knowing the specific position of the weld on the moving track at each moment and creating a time-position change curve.

[0037] S6. The position information converted by the number is translated into the moving distance and speed information of each segment of the welding device. While controlling the rotating mechanism to rotate for the second time, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thus completing the weld tracking.

[0038] More specifically, in step S5, the control device controls the rotating mechanism to rotate within one cycle, which is divided into n equal parts. At the acquisition times t1, t2...tn, the number of the CCD photosensitive element that transmits the largest electrical signal is recorded. The interval between adjacent times is less than 0.5s. The smaller the time interval, the more accurate the tracking.

[0039] More specifically, in step S6, adjacent acquisition times in the plotted curve are connected by a smooth curve, and the control device controls the moving speed of the welding device in each adjacent acquisition time to be positively correlated with the slope of the tangent line of the curve at that time. Example

[0040] like Figures 1-3 As shown, the left and right positional relationship in this example is based on... Figure 2 or Figure 3 Based on the left and right sides, the welding equipment used to support the above-mentioned vision-based wire tracing method includes: an operating table 1, a rotating table 2 on the operating table 1, and a suction cup 3 on the top of the rotating table 2; a surface light source 4 on the right side of the rotating table 2 on the operating table 1, and an L-shaped mounting bracket 5 on the right side of the operating table 1. The L-shape is designed to minimize material usage. The upper beam of the mounting bracket 5 extends above the suction cup 3; a single-axis drive mechanism that can move linearly along the direction of the upper beam is provided at the top of the upper beam, and a welding torch assembly 8 is mounted at the lower part of the single-axis drive mechanism; a left-right groove 9 is provided on the lower surface of the upper beam, and a linearly distributed CCD photosensitive element 10 is provided at the top of the groove 9; and a control device is also included, which receives feedback from the CCD photosensitive element 10 and controls the operation of the rotating table 2, the single-axis drive mechanism, and the welding torch assembly 8.

[0041] More specifically, the single-axis drive mechanism includes: a drive motor 6 located at the right end of the upper beam, the rotating shaft of the drive motor 6 driving the ball screw to rotate, and a slider 7, the upper part of the slider 7 having a through hole, one end of the through hole being fitted with a screw nut, the ball screw passing through the through hole, and the screw nut being sleeved on the outside of the ball screw, so as to realize that the drive motor 6 drives the slider 7 to perform linear motion.

[0042] More specifically, the welding torch assembly 8 includes: a clamping mechanism and a welding torch; the welding torch clamping mechanism is fixed to the bottom of the slider 7, and the fixing point is located below the upper beam. The clamping mechanism clamps the welding torch. The welding torch clamping mechanism is existing technology and at least includes a clamping function. Depending on the actual situation, a vertically moving structure can also be added.

[0043] More specifically, the rotary table 2 includes: a rotating shaft, with a platform fixed on the upper part of the rotating shaft and the lower part connected to the drive motor 6, which drives the rotation; the drive motor 6 mentioned above are all servo motors, and only a closed-loop controlled power source can accurately meet the requirements of this case.

[0044] More specifically, the surface light source 4 is an LED lamp; the control device is an industrial computer, which can better execute the design concept of this invention.

[0045] This invention is applicable to partially connected plates, which can be plates damaged by welding repair, or two complete plates fixed by partial welding. In use, the connected plates to be welded are fixed to a rotating table by suction cups, and then the surface light source is turned on. The control device controls the rotating table to rotate one revolution. During this cycle, the electrical signal excited by the light transmitted through the weld seam received by the CCD photosensitive element in the groove is transmitted to the control device. The control device plots the change of the maximum illumination position over time within one cycle as 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, thus realizing low-cost intelligent welding.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A vision-based wire bonding tracking method, characterized in that: Includes the following steps: S1. Fix the partially connected plates to be welded onto the rotating mechanism; S2. An upward-emitting light source is provided below one side of the rotating mechanism as a backlight; S3. A linearly moving welding device is set in the area above the light source, and a groove in the same direction as the track is set on the moving track of the welding device, and a linearly distributed CCD photosensitive element is set at the top of the groove; S4. The CCD photosensitive elements are numbered sequentially and connected to the control device; S5. With the light source on, the control device controls the rotating mechanism to rotate for the first revolution and records the number of the CCD photosensitive element that transmits the largest electrical signal at each moment within one revolution, thus knowing the specific position of the weld on the moving track at each moment and creating a time-position change curve. S6. The position information converted by the number is translated into the moving distance and speed information of each segment of the welding device. While controlling the rotating mechanism to rotate for the second time, the control device controls the welding device to perform one or more welding cycles according to the drawn curve, thus completing the weld tracking.

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

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

4. A welding device based on the vision-based wire bonding tracking method of claim 1, characterized in that: include: The system includes an operating table with a rotating platform and a suction cup on top. A surface light source is located on the right side of the rotating platform, and an L-shaped mounting bracket extends from the right side of the operating table to above the suction cup. A single-axis drive mechanism capable of linearly moving along the direction of the upper beam is located at the top of the upper beam, and a welding torch assembly is mounted below the single-axis drive mechanism. The lower surface of the upper beam has left-right grooves, and linearly distributed CCD photosensitive elements are located at the top of the grooves. The system also includes a control device that receives feedback from the CCD photosensitive elements and controls the operation of the rotating platform, the single-axis drive mechanism, and the welding torch assembly.

5. The welding equipment according to claim 4, characterized in that: The single-axis drive mechanism includes: a drive motor located at the right end of the upper beam, the drive motor shaft driving the ball screw to rotate, and a slider. The slider has a through hole at its upper part, 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 that the drive motor drives the slider to make linear motion.

6. The welding equipment according to claim 5, characterized in that: The welding torch assembly includes: a clamping mechanism and a welding torch; the welding torch clamping mechanism is fixed to the bottom of the slider, and the fixing point is located below the upper beam, and the clamping mechanism clamps the welding torch.

7. The welding equipment according to claim 6, characterized in that: The rotary table includes: a rotating shaft, with a platform fixed on the upper part of the rotating shaft and the lower part connected to a drive motor, which drives the rotating shaft to rotate; all of the drive motors are 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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