Multi-beam laser weld seam recognition and welding path planning method for cylindrical cover welding packaging

Abstract

The present invention discloses a multi-beam laser weld seam identification and welding path planning method for cylindrical cover plate welding packaging, comprising: simultaneously projecting n parallel linear structure laser stripes (n ≥ 2) onto the surface of the cylinder and cover plate to be welded, photographing and acquiring images of all the linear structure laser stripes; identifying the inflection point coordinates of all the linear structure laser stripes in the acquired image, and fitting the outer circle of the cover plate and the inner circle of the outer cylinder based on the identified inflection point coordinates; calculating the inner wall circle of the cylinder based on the inner circle of the outer cylinder and the cylinder wall thickness, taking the central ellipse of the figure between the inner wall circle of the cylinder and the outer circle of the cover plate as the welding trajectory; and taking the widest part of the overlapping portion of the cover plate and the cylinder wall as the starting point of the welding trajectory. The present invention does not require the use of linear structure laser to scan the workpiece to obtain the three-dimensional surface contour. A single image can directly identify the center path of the weld seam, which is highly efficient.

Description

Technical Field

[0001] The present invention relates to the field of welding automation technology, and in particular to a multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging. Background Art

[0002] In industries such as shipping, chemical industry, and military equipment, cylindrical structures are used in various pressure vessels and reaction vessels. In recent years, with the demand for lightweight development of various industrial containers, the demand for small-sized cylindrical or thin-walled cylindrical structural parts has been increasing. Cylindrical containers usually have high strength and sealing requirements. The encapsulation welding of small-sized or thin-walled cylindrical covers usually has the characteristics of small welds and high welding precision requirements. The joints of this type of welding are mostly in the form of lock-bottom butt joints, that is, the inner wall of the cylinder end is recessed to a certain width to form a step, and the cover is installed in the step to complete the welding encapsulation.

[0003] However, due to the inability to ensure alignment of the central axes of the cylinder and cover plate during pre-welding clamping, positional errors occur between the cover plate and cylinder, causing the overlap area between the cover plate and cylinder wall to deviate from the pre-set weld trajectory. Because the lap joint is located below and obscured by the cover plate, this deviation cannot be directly observed. To minimize the thermal impact of welding, welding of ultra-thin-walled cylinders primarily utilizes a short, high-power, and highly concentrated welding heat source to heat the metal to be welded. This deviation between the weld area and the pre-set weld trajectory can severely impact the weld quality of thin-walled cylinder cover plates, preventing them from meeting strength and sealing requirements and even leading to weld defects and overall structural failure. Therefore, the weld trajectory should be aligned with the center of the overlap area between the cylinder wall and cover plate. Furthermore, the high heat input during welding can cause thermal deformation of the cover plate. This type of arc weld, with its starting and ending points aligned, is subject to repeated heating during welding, which can easily cause deformation and impact the overall structure of the part. If the weld starting point is set at a narrow overlap area between the cover plate and cylinder wall, repeated heating can further increase the risk of thermal deformation. Therefore, the starting point of the welding trajectory needs to be planned.

[0004] Currently, single-line laser scanning is the primary method used to identify welds. However, for small or thin-walled cylindrical cover plates, where the weld area is small, continuous single-line laser scanning is time-consuming and labor-intensive, with low accuracy, significantly reducing production efficiency. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a multi-beam laser weld recognition and welding path planning method for cylindrical cover welding packaging.

[0006] Technical solution: The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging of the present invention includes the following steps:

[0007] Simultaneously project n parallel line structure laser stripes onto the surface of the cylinder and cover to be welded (n ≥ 2), and capture and acquire images of all line structure laser stripes;

[0008] Identify the inflection point coordinates of all line structure laser stripes in the acquired image, and fit the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates;

[0009] Calculate the inner circle of the cylinder according to the inner circle of the outer cylinder and the wall thickness of the cylinder, and take the ellipse between the inner circle of the cylinder and the outer circle of the cover as the welding trajectory;

[0010] The widest part of the overlapping part between the cover plate and the cylinder wall is taken as the starting and ending points of the welding track.

[0011] Furthermore, the parallel line structure laser stripes are generated by a line structure laser, and the line structure laser stripe image is captured by a camera that forms a set angle with the laser projection direction, and the geometric features of the line structure laser stripes are restored based on the triangulation principle.

[0012] Furthermore, the inflection point includes an outer inflection point and an inner inflection point. The outer inflection point is the intersection of the line structure laser stripe and the adjacent surface of the cylindrical boss and the gap. The inner inflection point is the intersection of the line structure laser stripe and the adjacent surface of the cover plate and the gap. The total number of inflection points is 4*n.

[0013] Furthermore, the inner circle C of the outer cylinder is fitted according to 2*n outer inflection points. o equation:

[0014]

[0015] Among them, x o 、y o is the coordinate of the center of the inner circle of the outer cylinder, R o is the inner radius of the outer cylinder, x1 and y1 are the horizontal and vertical coordinates of the points on the inner circle of the outer cylinder;

[0016] Fit the outer circle C of the cover according to 2*n inner inflection points r equation:

[0017]

[0018] Among them, x r 、y r is the center coordinate of the outer circle of the cover; R r is the outer radius of the cover plate, and x2 and y2 are the horizontal and vertical coordinates of the points on the outer circle of the cover plate.

[0019] Furthermore, the equation of the inner wall of the cylinder is:

[0020] (x3-x0) 2 +(y3-y0) 2=(R o -t) 2

[0021] Among them, x o 、y o is the coordinate of the center of the inner circle of the outer cylinder, x3 and y3 are the horizontal and vertical coordinates of the point on the inner wall of the cylinder, R o is the inner radius of the outer cylinder, and t is obtained by subtracting the thickness of the cylinder boss from the total wall thickness of the cylinder.

[0022] Furthermore, the welding trajectory calculation method is:

[0023] First connect the inner wall of the cylinder to the center O i and the center of the outer circle of the cover O r , calculate O i O r The four intersection points of the straight line with the outer circle of the cover plate and the inner wall circle of the cylinder are marked as A1, B1, A2, and B2 respectively. The midpoint C1 of A1 and B1 and the midpoint C2 of A2 and B2 are taken as the endpoints of the major axis of the ellipse. i and O r Make an O at the midpoint i O r The intersection points of the perpendicular line with the two circles are A3, B3, A4, and B4 respectively; the midpoint C3 of A3 and B3 and the midpoint C4 of A4 and B4 are taken as the endpoints of the minor axis of the ellipse; the ellipse is calculated based on C1, C2, C3, and C4, that is, the central ellipse of the figure between the inner wall circle of the cylinder and the outer circle of the cover plate, which is used as the welding trajectory.

[0024] Furthermore, if |A1B1|>|A2B2|, the starting and ending points of the welding trajectory are C1, otherwise they are C2.

[0025] The system corresponding to the method includes:

[0026] The laser stripe image acquisition unit is used to simultaneously project n parallel line structure laser stripes onto the surface of the cylinder and cover to be welded, where n is greater than or equal to 2, and to capture and acquire images of all line structure laser stripes;

[0027] A fitting unit, used to identify the inflection point coordinates of all line structure laser stripes in the acquired image, and fit the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates;

[0028] The welding trajectory calculation unit is used to calculate the inner wall circle of the cylinder according to the inner circle of the outer cylinder and the wall thickness of the cylinder, and take the central ellipse of the figure between the inner wall circle of the cylinder and the outer circle of the cover plate as the welding trajectory;

[0029] The welding track starting point determination unit is used to take the widest part of the overlapping part of the cover plate and the cylinder wall as the starting and ending points of the welding track.

[0030] An electronic device for storing and executing the method, comprising:

[0031] a memory storing executable program code;

[0032] a processor coupled to the memory;

[0033] The processor calls the executable program code stored in the memory to execute the steps of the multi-beam laser weld seam recognition and welding path planning method for cylindrical cover welding packaging.

[0034] A computer-readable storage medium for storing and executing the method, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are called, the computer-readable storage medium is used to execute the steps of the multi-beam laser weld identification and welding path planning method for cylindrical cover plate welding packaging.

[0035] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are: taking into account the position error caused by the non-coincidence of the central axes of the cylinder and the cover plate, overcoming the problem that the lap joint is covered by the cover plate and the deviation of different axes cannot be directly observed, and reasonably planning the starting and ending points of welding, which can reduce the occurrence of welding defects; and only one photo needs to be taken for weld identification and welding trajectory planning, which significantly improves production efficiency, and is particularly suitable for welding of thin-walled cylinder cover plates or micro-cylinder cover plates with high welding precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the process of the present invention;

[0037] Figure 2 This is a schematic diagram of a multi-beam laser weld seam recognition system for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of a cylindrical cover plate to be welded provided in an embodiment of the present invention;

[0039] Figure 4 An image obtained by a multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of fitting the inner circle of the outer cylinder and the outer circle of the cover plate according to a multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

[0041] Figure 6 Schematic diagram of the geometric features of the end of the cylinder to be welded, according to a multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

[0042] Figure 7 A schematic diagram of welding trajectory calculation for a multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

[0043] Figure 8 A schematic diagram of a cylindrical cover plate welding process provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0046] The present invention uses a multi-beam laser detection method to identify the cylindrical cover plate to be welded. Only one picture needs to be taken to identify the weld and plan the welding trajectory. It has important significance and value for improving the production efficiency and welding quality of thin-walled cylindrical cover plates.

[0047] like Figure 1 As shown, the multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging of the present invention includes the following steps:

[0048] S1, simultaneously project n (n ≥ 2) parallel line structure laser stripes onto the surface of the cylinder and cover to be welded. Typical scenarios are as follows Figure 2 As shown, the line structure laser generator 1 projects parallel line structure laser stripes onto the surface of the cylinder and cover plate 3 to be welded. Figure 3 As shown, it consists of an outer cylinder 31 and a cover plate 32. There is a gap 33 between the cover plate and the outer cylinder. The inner wall 34 of the cylinder is blocked by the cover plate 32. The thickness of the cylinder wall is indicated as 35, and the thickness of the cylinder boss is 36.

[0049] S2, such as Figure 2 As shown, the line structure laser stripe image is captured by the camera 2 which is at a set angle to the laser projection direction, as shown in FIG. Figure 4The angle between the camera and the incident direction of the three parallel linear laser stripes 5 is determined based on actual conditions to capture clear images of the linear laser stripes. In this embodiment, 30° is used. A computer 4 processes the captured image data, extracts the coordinates of high-brightness pixels in the image, and restores the geometric features of the laser stripes using the principle of triangulation.

[0050] S3. Identify the inflection point coordinates of the laser stripes in the acquired image. The relationship between the number of inflection points m and the number of stripes n is m=4n. The inflection points include outer inflection points and inner inflection points. The outer inflection point is the intersection of the line structure laser stripes and the adjacent surface of the cylindrical boss and the gap. The inner inflection point is the intersection of the line structure laser stripes and the adjacent surface of the cover plate and the gap. Figure 5 As shown in the figure, 12 inflection points appear when the three stripes are projected onto the cover surface. 12 points in total are identified: P1, P2, P3, P4, Q1, Q2, Q3, Q4, R1, R2, R3, and R4. The geometric features of the end of the cylinder to be welded are as follows: Figure 6 As shown, it includes the inner circle of the outer cylinder 6, the outer circle of the cover plate 7, the inner wall circle of the cylinder 8, and the outer circle of the outer cylinder 9, and 10 is the welding track.

[0051] S4, fitting the equation of the inner circle of the outer cylinder 6 according to the outer inflection point, and fitting the equation of the outer circle of the cover plate 7 according to the inner inflection point. Figure 5 As shown, the equation of the inner circle of the outer cylinder is fitted according to points P1, P4, Q1, Q4, R1, and R4:

[0052]

[0053] Among them, x o 、y o is the coordinate of the center of the inner circle of the outer cylinder, R o is the radius of the inner circle of the outer cylinder, and x1 and y1 are the horizontal and vertical coordinates of the points on the inner circle of the outer cylinder.

[0054] According to the points P2, P3, Q2, Q3, R2, and R3, the equation of the outer circle of the cover is fitted:

[0055]

[0056] Among them, x r 、y r is the coordinate of the center of the outer circle of the cover, R r is the outer radius of the cover plate, and x2 and y2 are the horizontal and vertical coordinates of the points on the outer circle of the cover plate.

[0057] S5. Calculate the equation of the inner wall of the cylinder:

[0058] (x3-x0) 2 +(y3-y0) 2 =(R o -t) 2

[0059] Among them, x3 and y3 are the horizontal and vertical coordinates of the point on the inner wall of the cylinder, such as Figure 6 As shown, t is obtained by subtracting the cylindrical boss thickness 36 from the cylindrical wall thickness 35.

[0060] S6, calculate welding trajectory 10, such as Figure 7 When the cover plate and the cylinder are not coaxial, the welding trajectory 10 should be an ellipse. The welding trajectory 10 is calculated as follows: First, connect the center of the inner wall of the cylinder O i and the center of the outer circle of the cover O r , calculate O i O r The four intersection points of the line and the two circles are A1, B1, A2, and B2. The midpoint C1 of A1 and B1 and the midpoint C2 of A2 and B2 are taken as the endpoints of the major axis of the ellipse. i O r The perpendicular line intersects the two circles at points A3, B3, A4, and B4. Take C3, the midpoint between A3 and B3, and C4, the midpoint between A4 and B4, as the endpoints of the minor axis of the ellipse. Calculate the ellipse based on C1, C2, C3, and C4.

[0061] S7. Determine the starting and ending points of the welding path. If |A1B1|>|A2B2|, then the starting and ending points 11 of the welding path are C1, otherwise they are C2.

[0062] like Figure 8 As shown, the cylindrical cover plate packaging welding method provided in this embodiment is laser welding, in which the laser 12 penetrates the cover plate and fuses it with the cylindrical wall. Since the inner wall of the cylinder and the overlapping part of the cylinder wall and the cover plate are blocked by the cover plate at 13, it is impossible to directly observe the overlapping part and plan the welding trajectory. Therefore, it is necessary to obtain the inner circle contour of the outer cylinder. The inner wall circle of the cylinder is concentric with the inner circle of the outer cylinder. The difference between the radii of the two circles is the difference between the wall thickness of the cylinder and the wall thickness of the area to be welded. Based on this, the equation of the inner wall circle of the cylinder is obtained. The equation of the outer circle of the cover plate is obtained, and the ellipse located inside the outer circle of the cover plate and in the middle of the area outside the inner wall circle of the cylinder is taken as the welding trajectory. This can ensure that the weld is always located in the center of the overlapping area of ​​the cover plate and the cylinder wall. The starting point and the end point of the elliptical welding trajectory are at the same position. It is repeatedly heated during the welding process, and the heat generated by the welding is relatively large. If the starting point is set at a narrow position where the overlapping part of the cover plate and the cylinder wall is relatively narrow, it is more likely to cause severe thermal deformation, affecting the welding quality. Therefore, the widest position of the overlapping part between the cover plate and the cylinder wall is selected as the welding starting point and end point.

[0063] The proposed method accounts for positional errors caused by misalignment between the cylinder and cover axis during assembly, reducing welding defects. It is particularly suitable for welding cylinder and cover plates, particularly for welding micro-cylinders, where high welding precision is required. Compared to existing techniques, this method eliminates the need for linear laser scanning to obtain the three-dimensional surface profile of the workpiece. Instead, a single image directly identifies the weld center path, resulting in high efficiency.

[0064] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A multi-beam laser weld seam recognition and welding path planning method for cylindrical cover welding packaging, characterized in that: The following steps are involved: Simultaneously project n parallel line structure laser stripes onto the surface of the cylinder and cover to be welded (n ≥ 2), and capture and acquire images of all line structure laser stripes; Identify the inflection point coordinates of all line structure laser stripes in the acquired image, and fit the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates; The inner circle of the cylinder is calculated based on the inner circle of the outer cylinder and the wall thickness of the cylinder. The ellipse between the inner circle of the cylinder and the outer circle of the cover is taken as the welding trajectory. The calculation method of the welding trajectory is: First connect the inner wall of the cylinder to the center O i and the center of the outer circle of the cover O r , calculate O i O r The four intersection points of the straight line with the outer circle of the cover plate and the inner wall circle of the cylinder are marked as A1, B1, A2, and B2 respectively. The midpoint C1 of A1 and B1 and the midpoint C2 of A2 and B2 are taken as the endpoints of the major axis of the ellipse. i and O r Make an O at the midpoint i O r The intersection points of the perpendicular line with the two circles are A3, B3, A4, and B4 respectively. The midpoint C3 of A3 and B3 and the midpoint C4 of A4 and B4 are taken as the endpoints of the minor axis of the ellipse. The ellipse is calculated based on C1, C2, C3, and C4, that is, the central ellipse of the figure between the inner circle of the cylinder and the outer circle of the cover plate, which is used as the welding trajectory. The widest part of the overlapping part between the cover plate and the cylinder wall is taken as the starting and ending points of the welding track.

2. The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging according to claim 1 is characterized in that: The parallel line structure laser stripes are generated by a line structure laser, and the line structure laser stripe image is captured by a camera that forms a set angle with the laser projection direction, and the geometric features of the line structure laser stripes are restored based on the triangulation principle.

3. The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging according to claim 1 is characterized in that: The inflection points include outer inflection points and inner inflection points. The outer inflection points are the intersections of the line structure laser stripes with the cylindrical boss and the adjacent surface of the gap. The inner inflection points are the intersections of the line structure laser stripes with the cover plate and the adjacent surface of the gap. The total number of inflection points is 4*n.

4. The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging according to claim 3 is characterized in that: Fit the inner circle C of the outer cylinder according to 2*n outer inflection points o equation: Among them, x o 、y o is the coordinate of the center of the inner circle of the outer cylinder, R o is the inner radius of the outer cylinder, x1 and y1 are the horizontal and vertical coordinates of the points on the inner circle of the outer cylinder; Fit the outer circle C of the cover according to 2*n inner inflection points r equation: Among them, x r 、y r is the center coordinate of the outer circle of the cover; R r is the outer radius of the cover plate, and x2 and y2 are the horizontal and vertical coordinates of the points on the outer circle of the cover plate.

5. The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging according to claim 1 is characterized in that: The equation of the inner wall of the cylinder is: (x3-x0) 2 +(y3-y0) 2 =(R o -t) 2 Among them, x o 、y o is the coordinate of the center of the inner circle of the outer cylinder, x3 and y3 are the horizontal and vertical coordinates of the point on the inner wall of the cylinder, R o is the inner radius of the outer cylinder, and t is obtained by subtracting the thickness of the cylinder boss from the total wall thickness of the cylinder.

6. The multi-beam laser weld seam recognition and welding path planning method for cylindrical cover plate welding packaging according to claim 1 is characterized in that: If |A1B1|>|A2B2|, the starting and ending points of the welding trajectory are C1, otherwise they are C2.

7. A multi-beam laser weld seam recognition and welding path planning system for cylindrical cover plate welding packaging, characterized by: include: The laser stripe image acquisition unit is used to simultaneously project n parallel line structure laser stripes onto the surface of the cylinder and cover to be welded, where n is greater than or equal to 2, and to capture and acquire images of all line structure laser stripes; A fitting unit, used to identify the inflection point coordinates of all line structure laser stripes in the acquired image, and fit the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates; The welding trajectory calculation unit is used to calculate the inner wall circle of the cylinder based on the inner circle of the outer cylinder and the cylinder wall thickness, and take the central ellipse of the figure between the inner wall circle of the cylinder and the outer circle of the cover as the welding trajectory; specifically: First connect the inner wall of the cylinder to the center O i and the center of the outer circle of the cover O r , calculate O i O r The four intersection points of the straight line with the outer circle of the cover plate and the inner wall circle of the cylinder are marked as A1, B1, A2, and B2 respectively. The midpoint C1 of A1 and B1 and the midpoint C2 of A2 and B2 are taken as the endpoints of the major axis of the ellipse. i and O r Make an O at the midpoint i O r The intersection points of the perpendicular line with the two circles are A3, B3, A4, and B4 respectively. The midpoint C3 of A3 and B3 and the midpoint C4 of A4 and B4 are taken as the endpoints of the minor axis of the ellipse. The ellipse is calculated based on C1, C2, C3, and C4, that is, the central ellipse of the figure between the inner circle of the cylinder and the outer circle of the cover plate, which is used as the welding trajectory. The welding track starting point determination unit is used to take the widest part of the overlapping part of the cover plate and the cylinder wall as the starting and ending points of the welding track.

8. An electronic device, characterized in that: The device comprises: a memory storing executable program code; a processor coupled to the memory; The processor calls the executable program code stored in the memory to execute the steps of the multi-beam laser weld recognition and welding path planning method for cylindrical cover welding packaging as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, which, when called, are used to execute the steps of the multi-beam laser weld identification and welding path planning method for cylindrical cover welding packaging as described in any one of claims 1 to 6.

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