Cylinder cover plate welding packaging-oriented multi-wire-beam laser welding seam identification and welding path planning method

Abstract

The invention discloses a multi-line-beam laser weld joint identification and welding path planning method for cylinder cover plate welding packaging, which comprises the following steps: simultaneously projecting n parallel line structure laser stripes to the surfaces of a cylinder to be welded and a cover plate, n being greater than or equal to 2, and shooting and acquiring all line structure laser stripe images; identifying the inflection point coordinates of all the line structure laser stripes in the obtained image, and fitting the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates; calculating the inner wall circle of the cylinder according to the inner circle of the outer cylinder and the wall thickness of the cylinder, and taking a central ellipse of a graph between the inner wall circle of the cylinder and the outer circle of the cover plate as a welding track; and the widest part of the overlapping part of the cover plate and the cylinder wall is taken as a welding track starting point. Line structure laser does not need to be adopted for scanning the workpiece to obtain the surface three-dimensional contour, the welding seam center path is directly recognized through a single picture, and efficiency is high.

Description

Technical Field

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

[0002] In the shipbuilding, chemical, military equipment and other industries, various pressure vessels and reaction vessels use cylindrical structures. In recent years, with the development requirements of lightweight development of various industrial containers, the demand for small-sized cylinders or thin-walled cylinder structures has increased. Cylindrical containers usually have higher strength and sealing requirements. The encapsulation welding of small-sized or thin-walled cylinder 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 bottom-locking docking, 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, since the cylinder wall and the cover plate cannot be clamped before welding to ensure that the central axis of the cylinder and the cover plate coincide, a position error occurs between the cover plate and the cylinder, and the overlap area between the cover plate and the edge of the cylinder wall is offset from the preset welding trajectory. Since the lap joint is located below the cover plate and is blocked by the cover plate, the offset cannot be directly observed. For the welding of ultra-thin-walled cylinders, in order to reduce the thermal impact of welding, a short-time, high-power, highly concentrated welding heat source is mainly used to heat the metal to be welded. The offset between the area to be welded and the preset welding trajectory will have a serious impact on the welding of the thin-walled cylinder cover plate, making it unable to meet the strength and sealing requirements, and even causing welding defects and failure of the overall welding structure. Therefore, the welding trajectory should be aligned with the center of the overlap area between the cylinder wall and the cover plate. In addition, the high heat input during welding will cause thermal deformation of the cover plate. The starting point and the end point of this type of arc weld are at the same position. It is repeatedly heated during welding and is prone to deformation, affecting the overall structure of the part. If the welding starting point is set at a narrow overlap width between the cover plate and the cylinder wall, and it is repeatedly heated, it will be more likely to cause thermal deformation. Therefore, it is necessary to plan the starting point of the welding trajectory.

[0004] At present, the single-line structure laser scanning method is mainly used to identify welds. However, for the packaging welding of small-sized or thin-walled cylindrical cover plates, the welding area is small, and the use of single-line structure laser continuous scanning is time-consuming and labor-intensive, and has low accuracy, which will significantly reduce 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 plate welding packaging.

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

[0007] Simultaneously project n parallel line structure laser stripes onto the surface of the cylinder and cover plate to be welded, where n≥2, and capture and obtain 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 plate 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 with the cylindrical boss and the adjacent surface of the gap. The inner inflection point is the intersection of the line structure laser stripe with the cover plate and the adjacent surface of 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 radius of the inner circle 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 plate 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 plate; R r is the radius of the outer circle 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 plate 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 O at the midpoint i O r The intersection points of the vertical 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 according to 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, 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 the cover plate to be welded, where n≥2, and to capture and acquire images of all line structure laser stripes;

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

[0028] A 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 recognition and welding path planning method for cylindrical cover plate 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, they are used to execute the steps of the multi-beam laser weld recognition and welding path planning method for cylindrical cover plate welding packaging.

[0035] Beneficial effects: Compared with the prior art, the remarkable 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 welding start and end points, which can reduce the occurrence of welding defects; and only one photo is needed to identify the weld and plan the welding trajectory, which significantly improves the production efficiency, and is particularly suitable for the welding of thin-walled cylinder cover plates or micro-cylinder cover plates with high requirements on welding accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the process of the method of the present invention;

[0037] Figure 2 A schematic diagram of a multi-beam laser weld 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 recognition and welding path planning method for cylindrical cover plate welding packaging provided in an embodiment of the present invention;

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

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

[0042] Figure 7 A schematic diagram of welding trajectory calculation of 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 purpose, 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, rather than 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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 of thin-walled cylindrical cover plate welding and improving welding quality.

[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 comprises the following steps:

[0048] S1. Simultaneously project n (n≥2) parallel laser stripes onto the surface of the cylinder and cover to be welded. Typical scenarios include: 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 is composed 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 and obtained by the camera 2 which is at a set angle to the laser projection direction, such as Figure 4The three parallel line structure laser stripes 5 shown, the angle between the camera and the incident direction of the line structure laser is determined according to the actual situation, preferably to be able to shoot clear line structure laser stripes, and in this embodiment, 30° is taken. The computer 4 processes the collected image data, extracts the high brightness pixel coordinates in the image, and restores the geometric features of the laser stripes according to the triangulation principle;

[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, and 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. There are 12 points in total, namely P1, P2, P3, P4, Q1, Q2, Q3, Q4, R1, R2, R3, and R4 in the recognition image. The geometric features of the end of the cylinder to be welded are as follows: Figure 6 As shown, it includes an inner circle 6 of an outer cylinder, an outer circle 7 of a cover plate, an inner wall circle 8 of a cylinder, and an outer circle 9 of an outer cylinder, and 10 is a welding track.

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

[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, R3, the equation of the outer circle of the cover plate is fitted:

[0055]

[0056] Among them, x r ,y r is the center coordinate of the outer circle of the cover plate, R r is the radius of the outer circle 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 cylinder boss thickness 36 from the cylinder 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 O of the inner wall of the cylinder i and the center of the outer circle of the cover plate O r , calculate O i O r The four intersection points of the straight 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 the midpoint C3 of A3 and B3 and the midpoint C4 of 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|, 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, and the laser 12 welds through the cover plate and fuses it with the cylinder wall. Since the inner wall of the cylinder at 13 and the overlapping part of the cylinder wall and the cover plate are blocked by the cover plate, 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, and the equation of the inner wall circle of the cylinder is obtained based on this. 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 outer area of ​​the inner wall circle of the cylinder is taken as the welding trajectory, which can ensure that the weld is always located at the center of the overlapping area between the cover plate and the cylinder wall. The starting point and the end point of the elliptical welding trajectory are located at the same position, and are repeatedly heated during the welding process. The heat generated by the welding has a large impact. If the starting point is set at a narrow position where the overlapping part of the cover plate and the cylinder wall is overlapped, it is more likely to cause serious thermal deformation, which affects 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 method proposed by the present invention takes into account the position error caused by the misalignment of the central axis of the cylinder and the cover plate caused by assembly, reduces the generation of welding defects, and is particularly suitable for the welding of cylinder cover plates or micro cylinder cover plates with high welding precision requirements. Compared with the prior art, the present invention does not need to use a linear structure laser to scan the workpiece to obtain the three-dimensional surface contour, and a single picture directly identifies the center path of the weld, which is highly efficient.

[0064] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A multi-beam laser weld recognition and welding path planning method for cylindrical cover plate 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 plate to be welded, where n≥2, and capture and obtain 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; 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 plate 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 intersection points of the line structure laser stripes with the cylindrical boss and the adjacent surface of the gap. The inner inflection points are intersection points 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 plate 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 plate; R r is the radius of the outer circle 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: The welding trajectory calculation method is: First, connect the inner wall of the cylinder to the center O i and the center of the outer circle of the cover plate 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 O at the midpoint i O r The intersection points of the vertical 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 according to 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, as the welding trajectory.

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

8. A multi-beam laser weld seam recognition and welding path planning system for cylindrical cover plate welding packaging, characterized in that: 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 the cover plate to be welded, where n≥2, and to capture and acquire images of all line structure laser stripes; A fitting unit, used for identifying the inflection point coordinates of all line structure laser stripes in the acquired image, and fitting the outer circle of the cover plate and the inner circle of the outer cylinder according to the identified inflection point coordinates; A 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; 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.

9. 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 plate welding packaging as described in any one of claims 1 to 7.

10. 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 recognition and welding path planning method for cylindrical cover plate welding packaging as described in any one of claims 1 to 7.

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