Path planning method for large-size leakage-stopping ring cylindrical surface additive manufacturing

Abstract

The invention belongs to the technical field of metal additive manufacturing, and particularly provides a large-size leakage-stopping ring cylindrical surface additive manufacturing path planning method which comprises the steps that a model of a to-be-formed leakage-stopping ring is input; giving an initial radius and a layer thickness, and calculating a space intersection contour of the model and a cylindrical surface of additive printing; converting three-dimensional space point coordinates of the spatial intersection contour into polar coordinates, and unfolding the spatial intersection contour to obtain a plane contour; the boundary contour of the plane contour is deviated inwards by a distance, and a contour track is obtained; constructing a linear trajectory inside by taking the contour trajectory as a new boundary; points of the track on the plane are converted into coordinates under a polar coordinate system, and the coordinates are inversely transformed back to the cylindrical surface to obtain a space track; and the space track information is converted into motion position information of the additive printing equipment, and a welding gun conducts printing according to the motion position information. The method is used for planning the additive machining path of the cylindrical surface of the large-size leakage stopping ring.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and in particular, relates to a path planning method for additive manufacturing of a large-size leak-proof ring cylinder. Background Art

[0002] The leak-proof ring is a sealing structure set between the turbine runner and the top cover and bottom ring to reduce water leakage. Its main function is to reduce the volume loss of the turbine and protect the upper crown and lower ring of the runner from wear. The leak-proof ring is divided into a rotating leak-proof ring and a fixed leak-proof ring when the unit is in operation. The rotating leak-proof ring includes an upper leak-proof ring and a lower leak-proof ring, and the fixed leak-proof ring includes a bottom ring leak-proof ring and a top cover leak-proof ring. At present, the manufacturing / installation method of the leak-proof ring is: first, the leak-proof ring is processed into a whole, and then hot-fitted or cold-fitted (the rotating leak-proof ring is hot-fitted and the fixed leak-proof ring is cold-fitted) is performed under the condition of ensuring a certain interference. The fixed leak-proof ring does not need to be processed after cold-fitting. This structural method can make the tensile and compressive stresses of the leak-proof ring more uniform. However, the hot-fitting and cold-fitting processes have high requirements for the control of the welding deformation of the leak-proof ring's own joints, and the installation process is complicated, which is prone to poor sealing caused by improper installation. In addition, the leak-proof ring is easily affected by cavitation, sand wear and dynamic stress during operation, resulting in damage and cracking. Once damage occurs, the unit needs to be overhauled, which is time-consuming and labor-intensive, causing huge economic losses to the power station.

[0003] Additive manufacturing provides a new solution for the manufacture of stop rings, which can achieve high-precision and high-efficiency manufacturing of stop rings and reduce welding deformation and installation complexity. However, the current additive manufacturing path planning method is mainly used for plane vertical forming. There are still some problems in the application of stop rings, such as the accuracy, continuity and manufacturing quality of path planning, which need to be further optimized. Therefore, it is of great practical significance to study a path planning method suitable for additive manufacturing of stop ring cylinders. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a path planning method for additive manufacturing of a large-sized leak-proof ring cylinder, and to plan the path for additive manufacturing of a large-sized leak-proof ring cylinder.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a path planning method for additive manufacturing of a large-size leak-proof ring cylinder, comprising the following steps: Step 1: Input the model of the leak-proof ring to be formed ; Step 2: Give the initial radius and layer thickness , the cylindrical surface for additive printing is S, , is the number of slice layers, The radius of the cylindrical surface to be printed by additive manufacturing is calculated by the model and The spatial intersection contour ; Step 3: The three-dimensional space point coordinates of the spatial intersection contour Convert to polar coordinates , with the circumferential arc length as the x coordinate, the height as the y coordinate, and the radius as the z coordinate, the spatial intersection contour is unfolded to obtain the plane contour ; Step 4: Contour the plane The boundary contour is offset inward by , and obtain a contour trajectory ; Step 5: For the new boundary, a straight line trajectory is constructed inside; Step 6: Convert the points of the trajectory on the plane into coordinates in the polar coordinate system, and then inversely transform them back to the cylindrical surface to obtain the spatial trajectory, which includes the contour trajectory. and straight line trajectory ; Step 7: Convert the spatial trajectory information into the motion position information of the additive printing device, and the welding gun prints according to the motion position information.

[0006] In the preferred embodiment, in step 1, the model The direction of the central axis of the cylindrical surface is , and passes through the origin of the coordinate system .

[0007] In a preferred solution, in step 2, the intersection profile is constructed as follows: S201, from the model Take a triangle patch from , is the edge of the triangle patch, , Side The two endpoints at both ends traverse the three edges in turn to calculate the intersection with the cylindrical surface; S202, project the triangle onto the horizontal plane , are the sides of a plane triangle, , They are the two endpoints of the side of the plane triangle, which are converted to calculate the intersection of the side of the plane triangle and the plane circle; S203. On a plane, assuming that the edge The intersection point with the cylindrical surface of radius r is The distance to the origin is equal to the radius r, so we can calculate ,if , then the intersection is valid, otherwise there is no intersection; S204, calculate all the intersection points of the plane triangle and the cylindrical surface Then, the intersection points are sorted by polar coordinate angles, and the intersection points are paired to determine an arc. The corresponding arc inside the triangle is determined as a valid line segment. S205: After calculating the plane intersection and determining the valid line segment, reverse projection is performed to return the actual height , connect the connected valid line segments to form the intersection contour line of the model and the cylindrical surface.

[0008] In the preferred solution, in step 3, the three-dimensional space point coordinates Convert to polar coordinates , calculated as follows: .

[0009] In the preferred solution, in step 3, when the spatial intersection contour is expanded to the plane contour, when the contour crosses the XOZ plane, it is necessary to process the angle mutation. The operation method is: construct a straight line at the zero angle position and intersect with the spatial intersection contour line. Two intersection points are arranged at each intersection position. , respectively inserted into the truncation contour line, then expanded, and recorded the part of the plane contour that belongs to the truncation line , .

[0010] In a preferred solution, in step 5, constructing a straight line trajectory includes the following steps: S501, calculate contour trajectory Minimum bounding box size occupied , , , and They are the minimum x coordinate, maximum x coordinate, minimum y coordinate and maximum y coordinate of the bounding box, respectively. The bounding box is able to enclose the contour trajectory. Minimum rectangular area range; S502, height range of straight track structure , given the trajectory offset , the number of trajectories , round down to an integer; S503, height margin , given the critical value of the straight line trajectory distance boundary and , construct scan lines; S504: Use the scan line to intersect with the boundary contour to construct a straight line trajectory on the two-dimensional plane : .

[0011] In a preferred solution, in step S503, the scanning line is constructed by: Situation 1: When When setting the initial offset , take the direction of the longest side of the minimum bounding box of the contour Construct a set of parallel scanning lines, the number of scanning lines is n The scan line is , For the bounding box The lowest projection point on , is the short side of the bounding box; Situation 2: When When , one scan line is reduced, and the number of scan lines is Item, set , set the second offset spacing and the last offset spacing , repeat the operation of case 1 to construct the scan line; Situation 3: When , keep the original number of scan lines n , , repeat the operation of case 1 to construct the scan line.

[0012] In the preferred solution, in step 6, when the plane trajectory is transformed back to the space trajectory, the contour on the XOZ plane needs to be merged and the contour trajectory needs to be eliminated, which includes the following steps: S601, search contour trajectory, if a certain continuous trajectory If the polar coordinate angle value of the corresponding original offset contour point is 0° or 360°, delete ; S602, the trajectories after deleting the points at both ends are merged into one trajectory at the points where the two 0° and 360° trajectory points are retained; S603, compare the two collinear straight line segment trajectories to determine which segment falls within the deleted trajectory segment Connect the two trajectories by using the endpoints on them.

[0013] In the preferred solution, in step 7, when the welding gun prints according to the motion position information, for the printing points in the trajectory on the same rotation radius , the radius r remains unchanged, and the print head of the welding gun moves in the height Z direction and the rotation circumferential direction respectively; Since the print head undergoes linear motion and circular rotation, it is necessary to calculate the combined motion speed. Exercise to The movement speed is calculated as follows: S701, motion increment calculation: , ; S702, Changes in axial arc length during movement for: ; S703, calculate the printing time according to the actual displacement: actual displacement , the expected printing speed is , then print time ; S704, calculate the translation speed of the z-axis: the angular speed of the rotation axis , the translation speed of the linear axis z .

[0014] In the preferred solution, in step 7, when printing, one or more of the following situations are considered: 1) Extend the track at the starting point: given overlap length , from the end point Start, pass the starting point , forward sequential search, record the sum of the lengths of the edges passed ,when When , stop searching and insert the extension point; 2) Adjust the head position of the straight line track, calculate the distance from the point to the contour from the starting point of the straight line track, and adjust the spacing if the distance is too close, and increase the printing speed of the point at the same time; 3) Use multi-gun collaborative printing: The printing equipment evenly distributes m print heads on the circular axis. Therefore, the trajectory is divided into m parts according to the polar coordinate angle, and each print head is responsible for its own area; 4) In order to eliminate the weld flow that may be caused by cylindrical horizontal printing, the straight track adopts a step-by-step printing sequence, and the operation is as follows: Trajectory stratification by radius size , Indicates layer, Indicates Tracks, the filling layer numbers are sorted from inside to outside, and within each contour layer, the filling tracks are sorted from bottom to top by height; First, print the first layer and the first track, that is, layer number k=1, track number j=1; then print the second layer and the first track, that is, k=2, j=1; then print the first layer and the second track, that is, k=1, j=2; then print the third layer and the first track, that is, k=3, j=1; then print the second layer and the second track, that is, k=2, j=2; and so on, according to the principle of increasing layer numbers and decreasing track numbers, print layer by layer and track by track in a step-by-step manner.

[0015] The path planning method for additive manufacturing of a large-size leak-proof ring cylinder provided by the present invention has the following beneficial effects: 1. A path planning method suitable for additive manufacturing of large-size stop-leak ring cylinders is provided for additive printing of stop-leak ring cylinders. The accuracy and continuity of path planning are improved, and manufacturing quality is guaranteed by accurately calculating spatial intersection contours, reasonably converting coordinates, optimizing trajectory construction, and processing contour merging.

[0016] 2. A processing method for unfolding the cylindrical contour is provided, which can generate a trajectory in the plane dimension and return it to the three-dimensional space, while transforming the three-dimensional Cartesian motion into a synthetic motion of rotation + height translation.

[0017] 3. By adopting a step-by-step printing sequence, each layer of weld can effectively provide sufficient base for the printing of the previous layer, effectively reducing the flow of the weld.

[0018] 4. Fully consider the movement of the print head in the height Z direction and the rotation circumference, accurately calculate the synthetic movement speed, ensure a smooth printing process, and improve printing accuracy.

[0019] 5. Extending the track at the starting point and adjusting the head position of the straight track enhances the reliability and quality of printing.

[0020] 6. Realize multi-gun collaborative printing: By splitting the trajectory according to polar coordinate angles, multiple print heads work together to improve printing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 Models of base parts and parts to be printed; Figure 2 It is the plane profile and trajectory distribution map; Figure 3 It is a schematic diagram of trajectory segmentation and step-by-step printing; DETAILED DESCRIPTION In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] A path planning method for additive manufacturing of a large-size leak-proof ring cylinder includes the following steps: Step 1: Input the STL model of the leak-proof ring to be formed .Model The direction of the central axis of the cylindrical surface is , and passes through the origin of the coordinate system .

[0023] Step 2: Give the initial radius and layer thickness , the cylindrical surface for additive printing is S, , is the number of slice layers, The radius of the cylindrical surface to be printed by additive manufacturing is calculated by the model and The spatial intersection contour .

[0024] The intersection profile is constructed as follows: S201, from the model Take a triangle patch from , is the edge of the triangle patch, , Side The two endpoints at both ends traverse the three edges in turn to calculate the intersection with the cylindrical surface.

[0025] S202, project the triangle onto the horizontal plane , are the sides of a plane triangle, , They are the two endpoints of the side of the plane triangle, which are converted to calculate the intersection of the side of the plane triangle and the plane circle.

[0026] S203. On a plane, assuming that the edge The intersection point with the cylindrical surface of radius r is The distance to the origin is equal to the radius r, so we can calculate ,if , then the intersection is valid, otherwise there is no intersection, and the edge and the circle may have two valid intersection points.

[0027] S204, calculate all the intersection points of the plane triangle and the cylindrical surface Finally, the intersection points are sorted according to the polar coordinate angles, and the intersection points are paired to determine an arc. The corresponding arcs inside the triangle are determined as valid line segments.

[0028] S205: After calculating the plane intersection and determining the valid line segment, reverse projection is performed to return the actual height , connect the connected valid line segments to form the intersection contour line of the model and the cylindrical surface.

[0029] Step 3: The three-dimensional space point coordinates of the spatial intersection contour Convert to polar coordinates , with the circumferential arc length as the x coordinate, the height as the y coordinate, and the radius as the z coordinate, the spatial intersection contour is unfolded to obtain the plane contour , the contour on a cylindrical surface is treated as a two-dimensional horizontal contour at the same height.

[0030] Three-dimensional space point coordinates Convert to polar coordinates , calculated as follows: .

[0031] In the preferred solution, when the spatial intersection contour is expanded to the plane contour, when the contour crosses the XOZ plane, it is necessary to deal with the angle mutation. The operation method is: construct a straight line at the zero angle position and intersect with the spatial intersection contour line. Two intersection points are arranged at each intersection position. , respectively inserted into the truncation contour line, then expanded, and recorded the part of the plane contour that belongs to the truncation line , .

[0032] is the part of the plane contour marked as the truncation line, The spatial intersection contours are unfolded to obtain the plane contours.

[0033] Step 4: In order to ensure the forming accuracy, the plane contour The boundary contour is offset inward by , and obtain a contour trajectory .

[0034] Step 5: For the new boundary, a straight line trajectory is constructed internally, including the following steps: S501, calculate contour trajectory Minimum bounding box size occupied , , , and They are the minimum x coordinate, maximum x coordinate, minimum y coordinate and maximum y coordinate of the bounding box, respectively. The bounding box is able to enclose the contour trajectory. Minimum rectangular area.

[0035] S502, height range of straight track structure , given the trajectory offset , the number of trajectories , round down to an integer.

[0036] S503, height margin , given the critical value of the straight line trajectory distance boundary and , construct scan lines, critical value and , determined by the specific process.

[0037] The scan line is constructed as follows: Situation 1: When When setting the initial offset , take the direction of the longest side of the minimum bounding box of the contour Construct a set of parallel scanning lines, the number of scanning lines is n The scan line is , For the bounding box The lowest projection point on , is the short side of the bounding box.

[0038] Situation 2: When When , one scan line is reduced, and the number of scan lines is Item, set , set the second offset spacing and the last offset spacing , repeat the operation of case 1 to construct the scan line.

[0039] Situation 3: When , keep the original number of scan lines n , , repeat the operation of case 1 to construct the scan line.

[0040] S504: Use the scan line to intersect with the boundary contour to construct a straight line trajectory on the two-dimensional plane : .

[0041] Step 6: Convert the points of the trajectory on the plane into coordinates in the polar coordinate system, and then inversely transform them back to the cylindrical surface to obtain the spatial trajectory, which includes the contour trajectory. and straight line trajectory .

[0042] When transforming the plane trajectory back to the space trajectory, it is necessary to process the merging of the contours on the XOZ plane and eliminate the contour trajectory, including the following steps: S601, search contour trajectory, if a certain continuous trajectory If the polar coordinate angle value of the corresponding original offset contour point is 0° or 360°, delete ; S602, the trajectories after deleting the points at both ends are merged into one trajectory at the points where the two 0° and 360° trajectory points are retained; S603, compare the two collinear straight line segment trajectories to determine which segment falls within the deleted trajectory segment Connect the two trajectories by using the endpoints on them.

[0043] Step 7: Convert the spatial trajectory information into the motion position information of the additive printing device, and the welding gun prints according to the motion position information.

[0044] When the welding gun prints according to the motion position information, for the printing points on the trajectory on the same rotation radius , the radius r remains unchanged, and the print head of the welding gun moves in the height Z direction and the rotation circumference direction respectively. Since the print head has linear motion and circular rotation motion, it is necessary to calculate the combined motion speed. Exercise to The movement speed is calculated as follows: S701, motion increment calculation: , ; S702, Changes in axial arc length during movement for: ; S703, calculate the printing time according to the actual displacement: actual displacement , the expected printing speed is , then print time ; S704, calculate the translation speed of the z-axis: the angular speed of the rotation axis , the translation speed of the linear axis z .

[0045] When printing, consider one or more of the following: 1) In order to ensure that the uneven lap morphology caused by arc starting and arc ending at the starting position of the contour offset trajectory is eliminated, it is necessary to extend the trajectory at the starting position to ensure that the head and tail welds are overlapped.

[0046] Given overlap length , from the end point Start, pass the starting point , forward sequential search, record the sum of the lengths of the edges passed ,when , stops searching and inserts an extension point.

[0047] 2) In order to eliminate the excessive accumulation of welds at the end points of the internal straight track and the contour track, adjust the head position of the straight track, calculate the distance from the point to the contour from the starting point of the straight track, adjust the spacing if the distance is too close, and increase the printing speed of the point at the same time; 3) In order to improve printing efficiency, multi-gun collaborative printing is adopted: the printing equipment evenly distributes m print heads on the circular axis, so the track is divided into m parts according to the polar coordinate angle, and each print head is responsible for its own area. During printing, the rotary axis moves, and different print heads match the appropriate printing speed according to the track point position to maintain a constant printing speed and point coordination.

[0048] 4) In order to eliminate the weld flow that may be caused by cylindrical horizontal printing, the straight track adopts a step-by-step printing sequence, and the operation is as follows: Trajectory stratification by radius size , Indicates layer, Indicates Tracks, the filling layer numbers are sorted from inside to outside, and within each contour layer, the filling tracks are sorted from bottom to top by height; First, print the first layer and the first track, that is, layer number k=1, track number j=1; then print the second layer and the first track, that is, k=2, j=1; then print the first layer and the second track, that is, k=1, j=2; then print the third layer and the first track, that is, k=3, j=1; then print the second layer and the second track, that is, k=2, j=2; and so on. According to the principle of increasing layer numbers and decreasing track numbers, after the number exceeds the critical value, it returns to the initial state and recycles, and prints layer by layer and line by line in a step-by-step manner.

[0049] Specific implementation cases: In order to more fully demonstrate the purpose and technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Figure 1 It is the base part and the part model to be printed. , additive printing is required on the cylindrical surface. With the origin (0,0,0) and direction (0,0,1) as the central axis, according to the general arc melting deposition process, the slice layer thickness is given , offset a set of cylindrical surfaces to intersect with the model to be printed. After constructing the spatial intersection contour, construct a straight line on the corresponding cylindrical surface at the XOZ zero angle position , intersecting with the contour, and then unfolding to the two-dimensional plane to obtain ABCDEF, such as Figure 2 As shown, the AB and DE sides are the truncation lines at the zero angle position of the polar coordinates. First, offset inward to obtain a contour trajectory , and then calculate the minimum bounding box , take the long side direction is the scan line direction, short side direction is the trajectory deviation direction. The lowest point in the deviation direction is point, therefore, the offset height is Distance between two points. According to process tests, the welding width is generally given , given an offset . Calculate the number of offsets And the height residual , adjust the offset spacing, and finally get Figure 2 Trajectory shown in: Initial spacing and first offset spacing , the distances of the first and last tracks from the boundary and the adjacent tracks have increased slightly, covering a small residual distance. Figure 3 As shown in the figure, the trajectory is transformed back to three-dimensional space and evenly divided according to the 4-welding gun printing platform. Each welding gun is responsible for its own area. The rotary axis drives the 4 welding guns to rotate synchronously. The welding guns each match the corresponding height displacement and speed in the height direction. The printing order is {path(1,1),path(2,1),path(1,2).path(3,1),path(2,2),path(1,3)}, which are the layer number and trajectory number, from inside to outside and from bottom to top.

[0050] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder, characterized in that: The following steps are involved: Step 1: Input the model of the leak-proof ring to be formed ; Step 2: Give the initial radius and layer thickness , the cylindrical surface for additive printing is S , , is the number of slice layers, The radius of the cylindrical surface to be printed by additive manufacturing is calculated by the model and The spatial intersection contour ; Step 3: The three-dimensional space point coordinates of the spatial intersection contour Convert to polar coordinates , with the circumferential arc length as the x coordinate, the height as the y coordinate, and the radius as the z coordinate, the spatial intersection contour is unfolded to obtain the plane contour ; Step 4: Contour the plane The boundary contour is offset inward by the distance , and obtain a contour trajectory ; Step 5: For the new boundary, a straight line trajectory is constructed inside; Step 6: Convert the points of the trajectory on the plane into coordinates in the polar coordinate system, and then inversely transform them back to the cylindrical surface to obtain the spatial trajectory, which includes the contour trajectory. and straight line trajectory ; Step 7: Convert the spatial trajectory information into the motion position information of the additive printing device, and the welding gun prints according to the motion position information.

2. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In step 1, the model The central axis direction of the cylindrical surface is , and passes through the origin of the coordinate system .

3. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In the step 2, the intersection contour is constructed as follows: S201, from the model Take a triangle patch from , is the edge of the triangle patch, , Side The two endpoints at both ends traverse the three edges of the triangle patch in turn and calculate the intersection with the cylindrical surface; S202, project the triangle onto the horizontal plane , are the sides of a plane triangle, , They are the two endpoints of the side of the plane triangle, which are converted to calculate the intersection of the side of the plane triangle and the plane circle; S203. On a plane, assuming that the edge The intersection point with the cylindrical surface of radius r is , , The distance to the origin is equal to the radius r, so we can calculate ,if , then the intersection is valid, otherwise there is no intersection; S204, calculate all the intersection points of the plane triangle and the cylindrical surface Then, the intersection points are sorted by polar coordinate angles, and the intersection points are paired to determine an arc. The corresponding arc inside the triangle is determined as a valid line segment. S205: After calculating the plane intersection and determining the valid line segment, reverse projection is performed to return the actual height , connect the connected valid line segments to form the intersection contour line of the model and the cylindrical surface.

4. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In step 3, the three-dimensional space point coordinates Convert to polar coordinates , calculated as follows: 。 5. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In step 3, when the spatial intersection contour is expanded to the plane contour, when the contour crosses the XOZ plane, it is necessary to handle the angle mutation. The operation method is: construct a straight line at the zero angle position and intersect with the spatial intersection contour line. Two intersection points are arranged at each intersection position. , respectively inserted into the truncation contour line, then expanded, and recorded the part of the plane contour that belongs to the truncation line , .

6. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In the step 5, constructing a straight line trajectory includes the following steps: S501, calculate contour trajectory Minimum bounding box size occupied , , , and They are the minimum x coordinate, maximum x coordinate, minimum y coordinate and maximum y coordinate of the bounding box, respectively. The bounding box is able to enclose the contour trajectory. Minimum rectangular area range; S502, height range of straight track structure , given the trajectory offset , the number of trajectories , round down to an integer; S503, height margin , given the critical value of the straight line trajectory distance boundary and , construct scan lines; S504: Use the scan line to intersect with the boundary contour to construct a straight line trajectory on the two-dimensional plane : 。 7. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 6, characterized in that: In step S503, the scanning line is constructed as follows: Situation 1: When When setting the initial offset , take the direction of the longest side of the minimum bounding box of the contour Construct a set of parallel scanning lines, the number of scanning lines is n The scan line is , For the bounding box The lowest projection point on , is the short side of the bounding box; Situation 2: When When , one scan line is reduced, and the number of scan lines is Item, set , set the second offset spacing and the last offset spacing , repeat the operation of case 1 to construct the scan line; Situation 3: When , keep the original number of scan lines n , , repeat the operation of case 1 to construct the scan line.

8. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In step 6, when the plane trajectory is transformed back to the space trajectory, the contour on the XOZ plane needs to be merged and the contour trajectory needs to be eliminated, which includes the following steps: S601, search contour trajectory, if a certain continuous trajectory If the polar coordinate angle value of the corresponding original offset contour point is 0° or 360°, delete ; S602, the trajectories after deleting the points at both ends are merged into one trajectory at the points where the two 0° and 360° trajectory points are retained; S603, compare the two collinear straight line segment trajectories to determine which segment falls within the deleted trajectory segment Connect the two trajectories by using the endpoints on them.

9. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In the step 7, when the welding gun prints according to the motion position information, for the printing points in the trajectory on the same rotation radius, , the radius r remains unchanged, and the print head of the welding gun moves in the height Z direction and the rotation circumferential direction respectively; Since the print head undergoes linear motion and circular rotation, it is necessary to calculate the combined motion speed. Exercise to The movement speed is calculated as follows: S701, motion increment calculation: , ; S702, Changes in axial arc length during movement for: ; S703, calculate the printing time according to the actual displacement: actual displacement , the expected printing speed is , then print time ; S704, calculate the translation speed of the z-axis: the angular speed of the rotation axis , the translation speed of the linear axis z .

10. A path planning method for additive manufacturing of a large-size leak-proof ring cylinder according to claim 1, characterized in that: In step 7, when printing, consider one or more of the following situations: 1) Extend the track at the starting point: given overlap length , from the end point Start, pass the starting point , forward sequential search, record the sum of the lengths of the edges passed ,when When , stop searching and insert the extension point; 2) Adjust the head position of the straight line track, calculate the distance from the point to the contour from the starting point of the straight line track, and adjust the spacing if the distance is too close, and increase the printing speed of the point at the same time; 3) Use multi-gun collaborative printing: The printing equipment evenly distributes m print heads on the circular axis. Therefore, the trajectory is divided into m parts according to the polar coordinate angle, and each print head is responsible for its own area; 4) In order to eliminate the weld flow that may be caused by cylindrical horizontal printing, the straight track adopts a step-by-step printing sequence, and the operation is as follows: Trajectory stratification by radius size , Indicates layer, Indicates Tracks, the filling layer numbers are sorted from inside to outside, and within each contour layer, the filling tracks are sorted from bottom to top by height; First, print the first layer and the first track, that is, layer number k=1, track number j=1; then print the second layer and the first track, that is, k=2, j=1; then print the first layer and the second track, that is, k=1, j=2; then print the third layer and the first track, that is, k=3, j=1; then print the second layer and the second track, that is, k=2, j=2; and so on, according to the principle of increasing layer numbers and decreasing track numbers, print layer by layer and track by track in a step-by-step manner.

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