An ultra-high flexible seven-axis welding robot for multi-vehicle type mixed line welding

Abstract

The application discloses a kind of for multi-vehicle type mixed line welding ultra-high flexible seven-axis welding robot applied to welding robot relevant technical field, by setting up multiple radial disc respectively on base and ground rail, cooperate with the laser of six-axis mechanical arm end and micro camera, realize the step-by-step monitoring of six-axis mechanical arm six degrees of freedom cumulative wear and ground rail seventh axis wear, the wear degree of both can be determined respectively, and deviation amplitude can be intuitively quantified, provide reliable basis for timely deviation compensation, it is convenient to targeted maintenance, effectively guarantee welding precision;Further add conical surface reflection half column and self-positioning component, control conical surface reflection half column occurs 180° rotation by electromagnetic on-off electricity, make the reflected light of dynamic change of laser drop point, make laser drop point on multiple radial disc more obvious, effectively avoid the problem that laser drop point is ignored due to reflection or environmental interference and misjudge excessive wear, further improve the accuracy and reliability of wear monitoring.

Description

Technical Field

[0001] This invention relates to the technical field of welding robots, and in particular to an ultra-high flexibility seven-axis welding robot for mixed-line welding of multiple vehicle models. Background Technology

[0002] In the automotive body welding industry, multi-model mixed-line production has become the mainstream mode, which places higher demands on the flexibility and precision of welding robots. Seven-axis welding robots, by adding a ground rail as an external seventh axis to the traditional six-axis robot, significantly expand the robot's workspace, enabling it to cover welding stations for multiple vehicle models. This makes it a core piece of equipment for realizing multi-model mixed-line welding.

[0003] However, with extended service life, the accuracy degradation problem of seven-axis welding robots has become increasingly prominent. On the one hand, the reducers, bearings, and other transmission components of the six-axis robotic arm are subjected to alternating loads over a long period, resulting in gradual wear accumulation and causing the kinematic parameters of each axis to deviate from their initial calibration values. On the other hand, the ground track, which serves as the external seventh axis, also experiences wear in its guide rails and transmission mechanisms during long-term reciprocating motion, further exacerbating the deterioration of the robot's end-effector positioning accuracy. This cumulative wear from multi-axis coupling directly causes the actual landing point of the welding torch to deviate from the target weld point, resulting in weld misalignment, reduced welding quality, and in severe cases, even welding defects.

[0004] To address the issue of precision degradation in industrial robots, Chinese patent CN116372942B discloses a robot joint compensation method, device, electronic device, and readable storage medium. It performs posture compensation adjustment by comparing the difference between the no-load posture and the loaded position. However, for welding robots, the load is low, so under low load conditions, some deviations are difficult to monitor through load deviation. Chinese invention patent application CN122438748A discloses a method for determining the health of robot joints. This method independently monitors individual robot joints. However, for this seven-axis robot, monitoring each joint separately and independently results in a complex system structure. It is also difficult to establish a direct correlation between the independent wear of each joint and the cumulative effect of the end effector precision. Furthermore, it is difficult to monitor and quantify the wear of the six-axis robotic arm as a whole and the ground rail in stages, making it difficult to determine the scope of the fault.

[0005] Therefore, there is an urgent need to provide a seven-axis welding robot that can perform step-by-step wear monitoring and quantify the cumulative deviation between the six-axis robotic arm and the ground rail, which serves as the seventh axis. Summary of the Invention

[0006] The core of this invention lies in setting multi-diameter disks with three-stage fan-shaped structures on the base and the ground rail respectively, and using a laser and a miniature camera to monitor and classify the laser landing point in real time, thereby realizing step-by-step quantitative monitoring of the cumulative wear of the six-axis robotic arm and the ground rail, solving the problem in the prior art of making it difficult to perform real-time quantitative monitoring of the cumulative wear of multi-axis coupling of seven-axis welding robots.

[0007] To solve the above problems, the present invention adopts the following technical solution.

[0008] A highly flexible seven-axis welding robot for multi-vehicle mixed-line welding includes a ground rail and a welding robotic arm slidably mounted on the ground rail. The welding robotic arm includes a base, a six-axis robotic arm mounted on the upper end of the base, and a welding torch mounted at the end of the six-axis robotic arm. Multi-diameter disks are mounted on the upper end of both the base and the ground rail. Each of the two multi-diameter disks is equipped with a microcontroller. One multi-diameter disk is located at the corner of the upper end of the base. From a top-down perspective, the other multi-diameter disk does not coincide with the base. A monitoring unit is also mounted at the end of the six-axis robotic arm. The monitoring unit includes a laser and a miniature camera. Both the laser and the miniature camera are simultaneously connected to the two microcontrollers. The multi-diameter disc includes a vertical shaft mounted on a base or ground rail via an electric rotating shaft and a light-receiving plate disposed outside the vertical shaft. The light-receiving plate includes an outer ring fan blade, a middle ring fan blade, and an inner ring fan blade that are fixedly connected to each other, and the three are integrally formed.

[0009] Furthermore, the outer ring fan blades, middle ring fan blades, and inner ring fan blades are all coaxially arranged with the vertical shaft, and the radius gradient of the three decreases.

[0010] Furthermore, the upper surfaces of both the outer and middle fan blades are provided with arc-shaped scale lines coaxial with the vertical axis. The outer fan blade has two arc-shaped scale lines, and the radii of the two arc-shaped scale lines are the same as the radii of the middle and inner fan blades, respectively. The middle fan blade has one scale line, which is the same as the radius of the inner fan blade.

[0011] Optionally, the light-receiving plate is fixedly connected to the vertical shaft, and the outer ring fan blades, middle ring fan blades, and inner ring fan blades are all made of opaque material, and the colors of the three are contrasting colors with the laser color emitted by the laser.

[0012] Optionally, the light-receiving plate is movably sleeved outside the vertical shaft. The outer ring fan blades, middle ring fan blades, and inner ring fan blades are all transparent, and each of them has multiple evenly distributed conical reflective semi-pillars at its bottom. A bushing is also fixedly connected to the outside of the vertical shaft. A self-replacing component is provided between the conical reflective semi-pillars and the bushing. An annular groove matching the bushing is opened at the lower end of the light-receiving plate. When the upper end of the bushing contacts the top wall of the annular groove, the upper end face of the conical reflective semi-pillar contacts the lower end of the light-receiving plate.

[0013] Furthermore, the central axes of the multiple conical reflective semi-pillars are all perpendicular to the central axis of the vertical shaft, and the axial lengths of the multiple conical reflective semi-pillars are different. The ends of the multiple conical reflective semi-pillars away from the bushing are respectively flush with the edges of the corresponding outer ring fan blade, middle ring fan blade, or inner ring fan blade.

[0014] Furthermore, a circular groove is provided on the bushing. The self-repositioning component includes a rod fixedly connected to the light-receiving plate, multiple sliders fixedly connected to the outer wall of the rod, and multiple guide grooves opened on the inner wall of the circular groove. The multiple sliders are slidably connected to the multiple guide grooves respectively. The self-repositioning component also includes an electromagnetic ring fixedly embedded inside the bushing and a limiting rope fixedly connected between the inner wall of the circular groove away from the conical reflective semi-pillar and the end of the rod. When energized, the electromagnetic ring generates a magnetic repulsive force on both the rod and the light-receiving plate.

[0015] Furthermore, the guide groove is spiral-shaped, and the radial span between the two ends of the guide groove is 180°, while the axial span of the guide groove does not exceed half the length of the insert rod.

[0016] Furthermore, the limiting rope is made of elastic material, and when the conical reflective semi-pillar contacts the outer wall of the bushing, the limiting rope is in a stretched and taut state.

[0017] Compared with the prior art, the advantages of this invention are: (1) This solution sets up multi-path disks on the base and the ground rail respectively, and uses a laser and a miniature camera at the end of the six-axis robotic arm to realize step-by-step monitoring of the cumulative wear of the six degrees of freedom of the six-axis robotic arm and the wear of the seventh axis of the ground rail. It can determine the wear degree of both separately, which is convenient for targeted maintenance. The multi-path disk adopts a structure of three-level fan blades with outer ring, middle ring and inner ring and arc scale line, which can intuitively quantify the deviation range and provide a reliable basis for timely deviation compensation according to the area where the laser falls, effectively ensuring welding accuracy.

[0018] (2) The light receiving plate is designed as a movable structure, which, together with the conical reflective half-column and the self-repositioning component, causes the conical reflective half-column to rotate 180° when the electromagnet is powered on and off. The laser landing point generates dynamically changing reflected light, making the image information acquired by the miniature camera more eye-catching. This effectively avoids the problem of misjudging the wear amount due to the laser landing point being ignored because of reflection or environmental interference, and further improves the accuracy and reliability of wear monitoring. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present invention; Figure 2 This is a partial perspective view of the present invention from another angle; Figure 3 This is a perspective view of the welding robotic arm portion of the present invention; Figure 4 This is a top view of part of the invention; Figure 5 This is a top view of the multi-diameter disk of the present invention; Figure 6 This is a schematic diagram illustrating the process of determining the laser impact point area by rotating the multi-path disk according to the present invention. Figure 7 This is a top perspective view of the multi-diameter disk in the second embodiment of the present invention; Figure 8 This is a bottom perspective view of the multi-diameter disk in the second embodiment of the present invention; Figure 9 This is a perspective view of the cone-shaped reflective semi-cylinder after reversal in the second embodiment of the present invention; Figure 10 This is a front cross-sectional view of the multi-diameter disk in the second embodiment of the present invention; Figure 11 This is a schematic diagram of the cone-shaped reflective semi-cylinder after reversal in the second embodiment of the present invention; Figure 12 This is a cross-sectional schematic diagram of the self-transposition component in the second embodiment of the present invention; Figure 13 This is a schematic diagram illustrating the continuous change of the reflected laser beam during the rotation and reversal process of the conical reflecting semi-cylinder in the second embodiment of the present invention. Explanation of the labels in the diagram: 1. Base, 2. Six-axis robotic arm, 3. Welding torch, 4. Ground rail, 5. Multi-diameter disc, 51. Vertical shaft, 52. Light receiving plate, 521. Outer ring fan blade, 522. Middle ring fan blade, 523. Inner ring fan blade, 53. Conical reflective semi-column, 501. Annular groove, 502. Insert rod, 503. Slider, 6. Shaft sleeve, 61. Guide groove, 62. Limiting rope, 63. Electromagnetic ring, 7. Monitoring unit. Detailed Implementation

[0020] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0021] First implementation method: like Figures 1-2 In the figure, 'a' represents a laser. A highly flexible seven-axis welding robot for multi-vehicle mixed-line welding includes a ground rail 4 and a welding robotic arm that slides on the ground rail 4. The welding robotic arm includes a base 1, a six-axis robotic arm 2 mounted on the upper end of the base 1, and a welding torch 3 mounted at the end of the six-axis robotic arm 2. The ground rail 4 serves as the external seventh axis, which together with the six axes of the six-axis robotic arm 2 forms a seven-degree-of-freedom welding robot.

[0022] like Figure 2 and Figure 4Both the base 1 and the ground rail 4 are equipped with multi-diameter disks 5. Each of the two multi-diameter disks 5 is equipped with a micro controller. One multi-diameter disk 5 is located at the corner of the upper end of the base 1. From a top-down perspective, the other multi-diameter disk 5 does not coincide with the base 1. The end of the six-axis robotic arm 2 is also equipped with a monitoring unit 7. The monitoring unit 7 includes a laser and a micro camera. Both the laser and the micro camera are simultaneously connected to the two micro controllers.

[0023] like Figure 3 At regular intervals (the specific intervals can be set according to actual needs), the six-axis robotic arm 2 can be controlled to move in multiple degrees of freedom, causing the laser on the monitoring unit 7 to emit laser light towards the multi-path disk 5, such as... Figure 5 The cumulative wear between the axes of the six-axis robotic arm 2 is determined by the positional offset of the actual laser landing point relative to the multi-path disk 5 (theoretical landing point). Through the design of the multi-path disk 5, the deviation amplitude can be quantified so as to make timely deviation compensation, thereby effectively ensuring the welding accuracy of this welding robot and reducing the occurrence of weld seam deviation from the target weld point.

[0024] By using the design of two multi-diameter disks 5, the cumulative wear of the six-axis robotic arm 2 and the cumulative wear of the external seventh axis ground rail 4 can be monitored step by step. This makes it easier to determine the wear degree of the six-axis robotic arm 2 and the ground rail 4 separately, so that targeted maintenance and wear compensation operations can be carried out in a timely manner.

[0025] Specifically, the step-by-step monitoring process for the two multi-diameter disks 5 is as follows: First, when the six-axis robotic arm 2 is in the reference position on the ground rail 4, the monitoring unit 7 at the end effector projects a laser onto the multi-diameter disk 5 on the base 1 to measure the cumulative deviation of each joint of the six-axis robotic arm 2. Then, the six-axis robotic arm 2 is controlled to move and project a laser onto the multi-diameter disk 5 on the ground rail 4. The resulting deviation includes the coupling value of the cumulative deviation of the six-axis robotic arm 2 and the movement deviation of the ground rail 4. Subtracting the two values ​​yields the decoupled wear deviation of the ground rail 4, thus determining the wear degree of each component. The above monitoring process can be performed periodically or triggered according to welding task switching or operator commands.

[0026] like Figures 5-6The multi-diameter disc 5 includes a vertical shaft 51 mounted on a base 1 or a ground rail 4 via an electric rotating shaft, and a light-receiving plate 52 disposed outside the vertical shaft 51. The light-receiving plate 52 is fixedly connected to the vertical shaft 51. The light-receiving plate 52 includes an outer ring fan blade 521, a middle ring fan blade 522, and an inner ring fan blade 523 fixedly connected to each other, and the three are integrally formed. The outer ring fan blade 521, the middle ring fan blade 522, and the inner ring fan blade 523 are all coaxially arranged with the vertical shaft 51, and their radii decrease in a gradient. Among them, the radius of the outer ring fan blade 521 corresponds to a preset emergency maintenance threshold, the radius of the middle ring fan blade 522 corresponds to a warning threshold, and the radius of the inner ring fan blade 523 corresponds to the allowable deviation range.

[0027] Both the outer ring fan blade 521 and the middle ring fan blade 522 have arc-shaped scale lines coaxial with the vertical axis 51 on their upper surfaces. The outer ring fan blade 521 has two arc-shaped scale lines, with radii matching those of the middle ring fan blade 522 and the inner ring fan blade 523, respectively. The middle ring fan blade 522 has one scale line with the same radius as the inner ring fan blade 523, effectively extending either the inner ring fan blade 523 or the middle ring fan blade 522. This allows the boundary ranges of the inner ring fan blade 523 and the middle ring fan blade 522 to be mapped onto the outer ring fan blade 521. This facilitates direct determination of the quantization interval of the offset based on the laser's position on the outer ring fan blade. In other words, the regions marked by the three components can be integrated onto a single outer ring fan blade 521. When the laser's position is on the outer ring fan blade... When the laser is applied to the outer fan blade 521 or the middle fan blade 522, it is easier to determine its actual offset range relative to the inner fan blade 523 or the middle fan blade 522, so that the offset can be more accurately understood. In use, when the laser point falls on the blank area, the corresponding micro controller controls the multi-diameter disk 5 to rotate at most one revolution through the electric rotating shaft. The micro camera always captures the image at the multi-diameter disk 5. When the laser point is detected to coincide with the multi-diameter disk 5, it means that the wear offset is still within the control range. If the laser point is not detected to coincide with the multi-diameter disk 5 after one revolution, it means that the wear accumulation exceeds the preset threshold (radius of the outer fan blade 521), and emergency maintenance is required to ensure the continuity and stability of the weld and the precise welding of the target weld point.

[0028] Specifically, the microcontroller performs hierarchical judgments based on the sector area where the laser strikes, and its specific logic is as follows: (a) When the laser point is located within the area enclosed by the inner fan blade 523 and its corresponding arc-shaped scale line, it is determined that the cumulative wear of the six-axis robotic arm 2 or the ground rail 4 is within the allowable range, and the system continues to operate normally; (b) When the laser strike point is located in the annular area between the middle fan blade 522 and the inner fan blade 523, it is determined that the wear is close to the threshold, and the microcontroller issues a warning signal to prompt the operator to arrange maintenance; (c) When the laser point is located in the annular area between the outer ring fan blade 521 and the middle ring fan blade 522, it is determined that the cumulative wear exceeds the safety threshold. The microcontroller issues a shutdown command and deviation compensation or component maintenance is required immediately. (d) When the laser point is located in the blank area outside the outer fan blade 521, the microcontroller controls the multi-path disk 5 to rotate around the vertical axis 51 by the electric rotating shaft to rotate up to one revolution to scan and confirm whether the laser point can re-align with the multi-path disk 5; if the laser point is not detected to fall into the range of the light receiving plate 52 after one revolution, it is determined that the wear has exceeded the compensable range and emergency shutdown and maintenance are required.

[0029] The actual range of the outer ring fan blade 521, the middle ring fan blade 522, and the inner ring fan blade 523 can be set according to the actual welding accuracy requirements, with the actual requirements taking precedence.

[0030] The outer ring fan blade 521, the middle ring fan blade 522, and the inner ring fan blade 523 are all made of opaque material, and their colors are contrasting colors with the laser color emitted by the laser. This allows for a clear color contrast when the laser falls on their surfaces, making the images captured by the miniature camera clearer and more contrasting, making it less likely to miss the laser's landing point, and thus making the monitoring results more accurate.

[0031] Second implementation method: This embodiment further improves the multi-diameter disk 5 based on the first embodiment, as detailed below: like Figures 7-8 The light-receiving plate 52 is movably sleeved outside the vertical shaft 51. The outer ring fan blades 521, the middle ring fan blades 522, and the inner ring fan blades 523 are all transparent, and each of them has multiple evenly distributed conical reflective semi-pillars 53 at its bottom. A bushing 6 is also fixedly connected to the outside of the vertical shaft 51. A self-replacing component is provided between the conical reflective semi-pillars 53 and the bushing 6. The lower end of the light-receiving plate 52 has an annular groove 501 that matches the bushing 6. When the upper end of the bushing 6 contacts the inner top wall of the annular groove 501, the upper end face of the conical reflective semi-pillar 53 contacts the light-receiving plate. The lower ends of the multiple conical reflective semi-pillars 52 are in contact with each other. The central axes of the multiple conical reflective semi-pillars 53 are perpendicular to the central axis of the vertical shaft 51. The axial lengths of the multiple conical reflective semi-pillars 53 are different. The ends of the multiple conical reflective semi-pillars 53 away from the bushing 6 are respectively flush with the edges of the corresponding outer ring fan blade 521, middle ring fan blade 522 or inner ring fan blade 523. This ensures that as long as the laser point is on the multi-diameter disk 5, or after the multi-diameter disk 5 is rotated by the electric rotating shaft, the laser point can be on the multi-diameter disk 5. This will cause the laser to produce constantly changing reflected light, thus improving the monitoring accuracy.

[0032] Among them, one half of the conical reflective semi-pillar 53 is a conical structure with a reflective coating on its surface, and the other half is a flat structure. The end away from the vertical axis 51 has a large diameter, and the other end has a small diameter. When the wear of this six-axis robot is not detected, the flat surface of the conical reflective semi-pillar 53 faces upward and contacts the lower end of the light-receiving plate 52. After rotation, the arc-shaped end face of its conical surface faces upward.

[0033] like Figure 10 and Figure 12 The bushing 6 has a circular groove. The self-positioning assembly includes a rod 502 fixedly connected to the light-receiving plate 52, multiple sliders 503 fixedly connected to the outer wall of the rod 502, and multiple guide grooves 61 formed on the inner wall of the circular groove. The multiple sliders 503 are slidably connected to the multiple guide grooves 61 respectively. The self-positioning assembly also includes an electromagnetic ring 63 fixedly embedded inside the bushing 6, and a limiting rope 62 fixedly connected between the inner wall of the circular groove away from the conical reflective semi-pillar 53 and the end of the rod 502. The limiting rope 62 is made of elastic material, and when the conical reflective semi-pillar 53 contacts the outer wall of the bushing 6, the limiting rope 62 is in a stretched and taut state, effectively ensuring that after the wear monitoring is completed and the electromagnetic ring 63 is de-energized, the limiting rope 62, under the action of restoring elasticity, can fully pull the conical reflective semi-pillar 53 to reset it. When energized, the electromagnetic ring 63 generates magnetic repulsion force on both the insertion rod 502 and the light-receiving plate 52. When testing is required, the energization of the electromagnetic ring 63 can be alternately controlled. Figure 9 and Figure 11 When energized, the multi-diameter disk 5 moves upward under the action of magnetic repulsion, while the conical reflective semi-pillar 53 moves radially outward. At this time, under the action of the slider 503 and the guide groove 61, the conical reflective semi-pillar 53 rotates 180°, so that the arc surface faces upward and the flat surface faces downward. After de-energization, under the action of the restoring elasticity of the limiting rope 62, as... Figure 13 The conical reflective semi-pillar 53 rotates in the opposite direction. Since the rotating shaft insertion rod 502 is not coaxial with the conical reflective semi-pillar 53, the incident angle between the laser landing point and the outer wall of the conical reflective semi-pillar 53 changes, resulting in light reflection in different directions. This presents a dynamic change in light visually, making the image information obtained by the miniature camera more obvious. Compared with the first embodiment where the laser landing point is fixed relative to the multi-path disk 5, this effectively avoids the problem of the laser landing point being ignored due to reflection or other unexpected situations, thus incorrectly concluding that the cumulative wear amount is too large.

[0034] To ensure that the light-receiving plate 52 moves up and down, a guide structure is provided between the light-receiving plate 52 and the vertical shaft 51. For example, a guide groove is provided on the inner wall of the light-receiving plate 52 and a guide block is provided on the outer wall of the vertical shaft 51, and the two match each other.

[0035] The guide groove 61 is spiral-shaped, and the radial span between the two ends of the guide groove 61 is 180°. The axial span of the guide groove 61 does not exceed half the length of the insertion rod 502, so that when the electromagnetic ring 63 is powered on and off, the conical reflective half-column 53 can only rotate half a turn at most, which can just convert the upward-facing arc surface and the cylindrical surface, thereby realizing that the position of the laser point on the multi-path disk 5 is not fixed, which makes it easy to realize the effect of the laser reflected light constantly changing.

[0036] It is worth noting that, in order to ensure the stable rotation of the conical reflective semi-pillar 53 and the stable movement of the light-receiving plate 52, both are made of low-density materials.

[0037] In summary, the core difference between the second and first implementation methods lies in the fact that the light-receiving plate 52 is made of transparent material, and a conical reflective semi-pillar 53 and a self-repositioning component are installed below it. During the detection process, the electromagnetic ring 63 is alternately switched on and off, driving the insertion rod 502 to move axially along the guide groove 61 and simultaneously rotate 180°, causing the conical reflective semi-pillar 53 to change direction, so that its conical or flat surface alternately faces the laser incident direction. When the conical surface of the conical reflective semi-pillar 53 faces upward, the laser beam undergoes diffuse reflection on its arc-shaped surface, and the miniature camera receives the dynamically changing reflected light spot; when the conical surface faces upward, the laser beam undergoes specular reflection, and due to rotation, its reflected light continuously changes. Through this switching of reflection modes, even if the ambient light changes or there is local reflection interference, the miniature camera can accurately locate the laser landing point through the characteristics of the light spot or reflected light changes in adjacent frame images, effectively avoiding the situation where the landing point is ignored due to reflection and the wear amount is misjudged as too large.

[0038] The above description is merely a preferred embodiment of the present invention; it encompasses all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A highly flexible seven-axis welding robot for multi-vehicle mixed-line welding, comprising a ground rail (4) and a welding robotic arm slidably mounted on the ground rail (4), the welding robotic arm comprising a base (1), a six-axis robotic arm (2) mounted on the upper end of the base (1), and a welding torch (3) mounted at the end of the six-axis robotic arm (2), characterized in that: Multi-diameter disks (5) are installed on the upper ends of the base (1) and the ground rail (4). Each of the two multi-diameter disks (5) is equipped with a micro controller. One of the multi-diameter disks (5) is located at the corner of the upper end of the base (1). From a top-down perspective, the other multi-diameter disk (5) does not overlap with the base (1). A monitoring unit (7) is also installed at the end of the six-axis robotic arm (2). The monitoring unit (7) includes a laser and a micro camera. The laser and the micro camera are simultaneously connected to the two micro controllers. The multi-diameter disc (5) includes a vertical shaft (51) mounted on a base (1) or a ground rail (4) via an electric rotating shaft and a light-receiving plate (52) disposed outside the vertical shaft (51). The light-receiving plate (52) includes an outer ring fan blade (521), a middle ring fan blade (522), and an inner ring fan blade (523) that are fixedly connected to each other, and the three are integrally formed.

2. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 1, characterized in that: The outer ring fan blade (521), the middle ring fan blade (522), and the inner ring fan blade (523) are all coaxially arranged with the vertical shaft (51), and the radius of the three decreases gradually.

3. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 2, characterized in that: The upper surfaces of the outer ring fan blade (521) and the middle ring fan blade (522) are provided with arc-shaped scale lines coaxial with the vertical axis (51). There are two arc-shaped scale lines on the outer ring fan blade (521), and the radii of the two arc-shaped scale lines are the same as the radii of the middle ring fan blade (522) and the inner ring fan blade (523), respectively. There is one scale line on the middle ring fan blade (522), and it is the same as the radius of the inner ring fan blade (523).

4. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 3, characterized in that: The light-receiving plate (52) is fixedly connected to the vertical shaft (51). The outer ring fan blade (521), the middle ring fan blade (522), and the inner ring fan blade (523) are all made of opaque material, and their colors are contrasting colors with the laser color emitted by the laser.

5. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 3, characterized in that: The light-receiving plate (52) is movably sleeved outside the vertical shaft (51). The outer ring fan blade (521), the middle ring fan blade (522), and the inner ring fan blade (523) are all transparent structures, and each of them has a plurality of evenly distributed conical reflective semi-pillars (53) at its bottom. The vertical shaft (51) is also fixedly connected to a bushing (6). A self-replacing component is provided between the conical reflective semi-pillars (53) and the bushing (6). The lower end of the light-receiving plate (52) is provided with an annular groove (501) that matches the bushing (6). When the upper end of the bushing (6) contacts the inner top wall of the annular groove (501), the upper end face of the conical reflective semi-pillar (53) contacts the lower end of the light-receiving plate (52).

6. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 5, characterized in that: The central axis of each of the multiple conical reflective semi-pillars (53) is perpendicular to the central axis of the vertical shaft (51), and the axial lengths of the multiple conical reflective semi-pillars (53) are different. The ends of the multiple conical reflective semi-pillars (53) away from the bushing (6) are respectively flush with the edges of the corresponding outer ring fan blade (521), middle ring fan blade (522) or inner ring fan blade (523).

7. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 6, characterized in that: The bushing (6) has a circular groove. The self-repositioning component includes a rod (502) fixedly connected to the light receiving plate (52), a plurality of sliders (503) fixedly connected to the outer wall of the rod (502), and a plurality of guide grooves (61) opened on the inner wall of the circular groove. The plurality of sliders (503) are slidably connected to the plurality of guide grooves (61). The self-repositioning component also includes an electromagnetic ring (63) fixedly embedded inside the bushing (6) and a limiting rope (62) fixedly connected between the inner wall of the circular groove away from the conical reflective half-pillar (53) and the end of the rod (502). When energized, the electromagnetic ring (63) generates magnetic repulsion force on both the rod (502) and the light receiving plate (52).

8. The ultra-high flexibility seven-axis welding robot for multi-vehicle mixed-line welding according to claim 7, characterized in that: The guide groove (61) is spiral-shaped, and the radial span between the two ends of the guide groove (61) is 180°. The axial span of the guide groove (61) does not exceed half the length of the insert rod (502).

9. A highly flexible seven-axis welding robot for multi-vehicle mixed-line welding according to claim 8, characterized in that: The limiting rope (62) is made of elastic material, and when the conical reflective semi-column (53) contacts the outer wall of the bushing (6), the limiting rope (62) is in a stretched and taut state.

Images