3D design of an aero-engine rotor blade tip additive welding trajectory planning method

Abstract

The present application relates to a kind of 3D design aero-engine rotor blade tip additive welding track planning method, including damage blade tip pre-welding processing, tip additive welding feature point vision coordinates extraction, tip additive welding feature point robot coordinates generation, tip additive welding track feature point conversion, tip additive welding track generation.The present application improves the speed of 3D blade additive welding track planning under the premise of ensuring the accuracy of welding track planning, avoids the problem of using high-power additive welding to compensate the accuracy error of track planning, can obtain higher quality additive weld, reduces subsequent machining workload, and improves the utilization rate of welding material.

Description

Technical Field

[0001] This invention relates to the field of additive welding technology, specifically to a 3D design method for additive welding trajectory planning at the tip of an aero-engine rotor blade. Background Technology

[0002] Rotor blades are one of the key components of aero-engines. During operation, they elongate under centrifugal force, and tip wear caused by friction between the blade tip and the sealing ring becomes the main form of blade damage. Restoring the blade tip shape using additive welding-precision subtraction can reduce the engine's total lifespan cost.

[0003] To achieve higher working efficiency, the blades of advanced engines are all designed in 3D, which means using complex surfaces to improve aerodynamic shape and increase working efficiency. Specifically, this is reflected in the design of large-angle positive bending of the blade tip leading edge and negative bending of the trailing edge, the angle between the leading and trailing edges and the blade tip, and the thickness of the leading and trailing edges being only 0.1 to 0.2 mm.

[0004] There are two difficulties in additive welding of blade tips using 3D design. First, the complex surface design makes it difficult to plan the welding trajectory. Second, the blade shape becomes distorted and deformed after service, making it impossible to plan the additive welding trajectory using the design drawings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a 3D design method for additive welding trajectory planning of aero-engine rotor blade tips. This method obtains point cloud data of damaged blades through 3D scanning, extracts the feature parameters required for tip additive welding trajectory planning and calculates the number of weld passes required to complete additive welding, obtains the coordinates of tip additive welding feature points through a top-mounted CCD camera, and calculates the tip additive welding trajectory based on the blade airfoil feature parameters.

[0006] The technical problem solved by this invention is achieved through the following technical solution:

[0007] A method for planning the additive welding trajectory of aero-engine rotor blade tips using 3D design, characterized in that the trajectory planning method includes the following steps:

[0008] Step 1: Pre-welding processing of damaged blade tips;

[0009] Step 2: Three-dimensional scanning of the damaged blade's shape;

[0010] Step 3: Extract the feature parameters required for blade tip welding trajectory planning;

[0011] Step 4: Plan the number of weld beads required for tip welding repair;

[0012] Step 5: Visual coordinate extraction of feature points for additive welding at the blade tip;

[0013] Step 6: Generating robot coordinates for feature points in blade tip additive welding;

[0014] Step 7: Calculation of feature points for additive welding trajectory at the blade tip;

[0015] Step 8: Generate the blade tip additive welding trajectory.

[0016] The specific operation of the pre-welding processing of the damaged blade tip in step 1 is as follows: the blade tip is machined and polished to achieve a surface roughness of Ra0.1 to 0.05, and the blade tip surface is perpendicular to the central axis of the blade after polishing.

[0017] The specific operation of the three-dimensional scanning of the damaged leaf shape in step 2 is as follows: the leaf surface is thoroughly cleaned with an organic solvent to prevent oil stains and other impurities adhering to the surface from affecting the acquisition accuracy; the damaged leaf is measured using a three-dimensional optical scanning device; to improve the scanning accuracy, a thin layer of imaging agent is sprayed onto the leaf surface to obtain the leaf point cloud; and the error point cloud is removed using a smoothing filter method.

[0018] The specific operation for extracting the characteristic parameters required for blade tip welding trajectory planning in step 3 is as follows: measure the characteristic parameters required for blade welding additive trajectory planning, including the leading edge positive bending length L1, the leading edge positive bending angle α1, the angle between the leading edge and the blade tip α2, the trailing edge negative bending length L2, the trailing edge negative bending angle β1, and the angle between the trailing edge and the blade tip β2.

[0019] The specific operation for planning the number of blade tip repair welds in step 4 is as follows: fit the digital model of the damaged blade with that of the unused blade, and measure the maximum missing height H at the blade tip. max Based on the height increase value h of each weld seam, calculate the number of weld seams required to complete the additive welding of the blade, using the following formula:

[0020]

[0021] The specific operation for extracting the visual coordinates of the additive welding feature points at the blade tip in step 5 is as follows: The processed blade is held in a flexible fixture to ensure the blade tip plane is horizontal. A top-mounted CCD camera is used to identify the damaged surface. After binarization, the blade tip surface contour is extracted. The leading edge point A0 and trailing edge point D0 of the blade are identified. The positive bending endpoint B0 of the leading edge is identified at a distance L1 from the leading edge point, and the negative bending endpoint C0 of the trailing edge is identified at a distance L2 from the trailing edge point. The visual coordinates of the feature points are read as follows:

[0022]

[0023] To improve trajectory planning accuracy and reduce subsequent blade material reduction work, n points are evenly set between the blade leading edge point A0 and the blade positive flex endpoint B0, and the visual coordinates are read as follows:

[0024]

[0025] m points were set on average between the end point of the blade's trailing edge inflection C0 and the blade's trailing edge point D0, and the visual coordinates were read as follows:

[0026]

[0027] The specific operation for generating the robot coordinates of the blade tip additive welding feature points in step 6 is as follows: The welding actuator is operated to adjust the welding torch to be perpendicular to the blade tip, with the torch nozzle in contact with the blade tip surface. The Z-axis coordinate is read and defined as Z0. The visual coordinates read in step 5 are converted into robot coordinates to obtain the planar coordinates of the blade tip feature points. The Z-axis coordinate Z0 of the blade tip is assigned a value, resulting in the following three-dimensional coordinates of the blade tip feature points on the robot:

[0028]

[0029] The specific operation for converting the feature points of the blade tip additive welding trajectory in step 7 is as follows: The leading edge positive bending trajectory planning comprehensively considers the welding torch distance d, the leading edge positive bending angle α1, and the angle between the leading edge and the blade tip α2, calculating the coordinates of the feature points for the leading edge positive bending welding trajectory planning; the trailing edge reverse bending trajectory planning comprehensively considers the welding torch distance d, the trailing edge reverse bending angle β1, and the angle between the trailing edge and the blade tip β2, calculating the coordinates of the feature points for the trailing edge reverse bending welding trajectory planning; the formula for calculating the coordinates of the feature points required for the q-th weld trajectory planning is as follows:

[0030]

[0031] Based on the calculation formula, the coordinates of the feature points required for the first weld seam trajectory planning are obtained:

[0032]

[0033]

[0034] Based on the calculation formula, the coordinates of the feature points required for the second weld seam trajectory planning are obtained:

[0035]

[0036] Based on the calculation formula, the coordinates of the feature points required for planning the trajectory of the p-th weld are obtained:

[0037]

[0038] The specific operation for generating the blade tip additive welding trajectory in step 8 is as follows: set the motion trajectory between adjacent feature points of each weld seam in the blade tip additive welding to be a straight line, set the motion speed between adjacent feature points, and obtain the 3D design of the aero-engine rotor blade additive welding trajectory.

[0039] The advantages and beneficial effects of this invention are as follows:

[0040] 1. The 3D design method for additive welding trajectory planning of aero-engine rotor blade tips uses a top-mounted CCD camera to obtain the coordinates of additive welding feature points at the blade tip. The additive welding trajectory is calculated by extracting feature parameters from the 3D point cloud data of the damaged blade. This method improves the speed of 3D blade additive welding trajectory planning while ensuring the accuracy of the welding trajectory planning. It avoids the problem of using high-power additive welding to compensate for trajectory planning accuracy errors, can obtain higher quality additive welds, reduce subsequent machining workload, and improve the utilization rate of welding materials. Attached Figure Description

[0041] Figure 1 a is a schematic diagram of the extraction of the leading edge positive bending length L1 characteristic parameter of the present invention;

[0042] Figure 1 b is a schematic diagram of the extraction of the trailing edge inflection length L2 feature parameter of the present invention;

[0043] Figure 2 a is a schematic diagram of the extraction of the characteristic parameter α1 of the leading edge positive bending angle in this invention;

[0044] Figure 2 b is a schematic diagram of the extraction of the trailing edge inflection angle β1 characteristic parameter of the present invention;

[0045] Figure 3 a is a schematic diagram of the feature parameter extraction of the angle α2 between the leading edge and the blade tip in this invention;

[0046] Figure 3 b is a schematic diagram of the extraction of the feature parameter β2 of the trailing edge and the tip of the blade in this invention;

[0047] Figure 4 This is a schematic diagram of the fitting between the damaged blade and the new blade in this invention;

[0048] Figure 5 The maximum missing height H at the leaf tip in this invention max Measurement diagram;

[0049] Figure 6 This is a schematic diagram illustrating the extraction of feature points for additive welding at the blade tip in this invention.

[0050] Figure 7 The robot coordinates (XY axes) for the blade tip additive welding feature points generated by this invention;

[0051] Figure 8 The robot coordinates (XZ axes) for the blade tip additive welding feature points generated in this invention.

[0052] Explanation of icon numbers:

[0053] 1. Damaged leaves; 2. New leaves. Detailed Implementation

[0054] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0055] A method for trajectory planning in additive welding repair of missing blade tip dimensions in aero-engine rotor blades is innovative in that the trajectory planning method includes the following steps:

[0056] Step 1, the specific operation of pre-welding processing of damaged blade tip is as follows: the blade tip is machined and polished to a surface roughness of Ra0.1 to 0.05. After polishing, the blade tip surface is perpendicular to the central axis of the blade.

[0057] Step 2, the specific operation of three-dimensional scanning of the damaged leaf shape is as follows: thoroughly clean the leaf surface with organic solvent to prevent oil stains and other impurities on the surface from affecting the acquisition accuracy; use three-dimensional optical scanning equipment to measure the damaged leaf. In order to improve the scanning accuracy, spray a thin layer of imaging agent on the leaf surface to obtain the leaf point cloud, and use smoothing filtering method to remove the error point cloud.

[0058] Step 3, the specific operation of extracting the feature parameters required for blade tip welding trajectory planning is as follows: Figure 1 a, Figure 1 As shown in b, the characteristic parameters required for blade welding additive manufacturing trajectory planning are measured: the leading edge positive bending length L1 and the trailing edge negative bending length L2. Figure 2 a, Figure 2 As shown in b, the characteristic parameters required for blade welding additive trajectory planning are the leading edge positive bending angle α1 and the trailing edge negative bending angle β1; as shown in... Figure 3 a, Figure 3 As shown in b, the characteristic parameters required for blade welding additive trajectory planning are measured: the angle α2 between the leading edge and the blade tip, and the angle β2 between the trailing edge and the blade tip.

[0059] Step 4, the specific operation for planning the number of weld beads for blade tip repair is as follows: (e.g.) Figure 4 , Figure 5 As shown, the digital model of damaged leaf 1 is fitted with that of unused new leaf 2, and the maximum missing height H at the leaf tip is measured. max Based on the height increase value h of each weld seam, calculate the number of weld seams required to complete the additive welding of the blade, using the following formula:

[0060]

[0061] Step 5, the specific operation for extracting the visual coordinates of feature points in blade tip additive welding is as follows: Figure 6As shown, a flexible fixture is used to hold the processed blade, ensuring the blade tip plane is horizontal. A top-mounted CCD camera is used to identify the damaged surface. After binarization, the blade tip surface contour is extracted, and the leading edge point A0 and trailing edge point D0 are identified. The positive bending endpoint B0 of the leading edge is identified at a distance L1 from the leading edge point, and the negative bending endpoint C0 of the trailing edge is identified at a distance L2 from the trailing edge point. The visual coordinates of the feature points are read as follows:

[0062]

[0063] To improve trajectory planning accuracy and reduce subsequent blade material reduction work, n points are evenly set between the blade leading edge point A0 and the blade positive flex endpoint B0, and the visual coordinates are read as follows:

[0064]

[0065]

[0066] m points were set on average between the end point of the blade's trailing edge inflection C0 and the blade's trailing edge point D0, and the visual coordinates were read as follows:

[0067]

[0068] Step 6, the specific operation for generating the robot coordinates of the blade tip additive welding feature points is as follows: The welding actuator is operated to adjust the welding torch to be perpendicular to the blade tip, with the torch nozzle in contact with the blade tip surface. The Z-axis coordinate is read and defined as Z0. The visual coordinates read in Step 5 are converted into robot coordinates to obtain the planar coordinates of the blade tip feature points. The Z-axis coordinate Z0 of the blade tip is assigned a value, resulting in the following three-dimensional coordinates of the blade tip feature points on the robot:

[0069]

[0070] Step 7, the specific operation for converting the feature points of the blade tip additive welding trajectory is as follows: Figure 7 , Figure 8 As shown, the leading edge positive bending trajectory planning of the blade comprehensively considers the welding gun distance d, the leading edge positive bending angle α1, and the angle between the leading edge and the blade tip α2, and calculates the coordinates of the feature points of the leading edge positive bending welding trajectory planning; the trailing edge negative bending trajectory planning of the blade comprehensively considers the welding gun distance d, the trailing edge negative bending angle β1, and the angle between the trailing edge and the blade tip β2, and calculates the coordinates of the feature points of the trailing edge negative bending welding trajectory planning.

[0071] Coordinates of feature points required for the first weld seam trajectory planning:

[0072]

[0073] Coordinates of feature points required for planning the trajectory of the second weld seam:

[0074]

[0075] Coordinates of feature points required for planning the trajectory of the p-th weld bead:

[0076]

[0077] Step 8, the specific operation for generating the blade tip additive welding trajectory is as follows: set the motion trajectory between adjacent feature points of each weld seam in the blade tip additive welding to be a straight line, set the motion speed between adjacent feature points, and obtain the 3D design of the aero-engine rotor blade additive welding trajectory.

[0078] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for planning the additive welding trajectory of aero-engine rotor blade tips using 3D design, characterized in that: The trajectory planning method includes the following steps: Step 1: Pre-welding processing of damaged blade tips; Step 2: Three-dimensional scanning of the damaged blade's shape; Step 3: Extract the feature parameters required for blade tip welding trajectory planning; Step 4: Plan the number of weld beads required for tip welding repair; Step 5: Visual coordinate extraction of feature points for additive welding at the blade tip; Step 6: Generating robot coordinates for feature points in blade tip additive welding; Step 7: Calculation of feature points for additive welding trajectory at the blade tip; Step 8: Generation of additive welding trajectory for blade tip; The specific operation for extracting the feature parameters required for blade tip welding trajectory planning in step 3 is as follows: Measure the feature parameters required for blade welding additive trajectory planning, including the positive bending length of the blade leading edge. Angle of positive curvature at the leading edge Angle between the leading edge and the leaf tip Trailing edge reverse bending length trailing edge reverse bend angle Angle between the trailing edge and the leaf tip ; The specific operation for planning the number of blade tip repair welds in step 4 is as follows: fit the digital model of the damaged blade with that of the unused blade, and measure the maximum missing height of the blade tip. H max Based on the increase value of each weld seam h The formula for calculating the number of weld passes required to complete the additive welding of the blade is as follows: ； The specific operation for extracting the visual coordinates of the additive welding feature points at the blade tip in step 5 is as follows: The processed blade is held in a flexible fixture to ensure the blade tip plane is horizontal. A top-mounted CCD camera is used to identify the damaged surface. After binarization, the blade tip surface contour is extracted, and the leading edge point A0 and trailing edge point D0 are identified, along with the distance from the leading edge point... L 1 Position identification: the end point B0 of the positive curve at the leading edge of the blade, and the distance from the trailing edge of the blade. L 2 The location was identified at the end point C0 of the blade's trailing edge inflection. The visual coordinates of the feature point were read as follows: A0, the leading edge point of the blade ( , ) The end point of the positive bend at the leading edge of the blade is B0 ( , ) The end point of the blade trailing edge recurve C0 ( , ) trailing edge point D0 ( , ); To improve trajectory planning accuracy and reduce subsequent blade material reduction work, an average distance is set between the blade leading edge point A0 and the blade positive camber endpoint B0. n The visual coordinates of each point are as follows: Leaf leading edge insertion point E01 ( , ) Leaf leading edge insertion point E02 ( , ) … Leaf leading edge insertion point E0 n-1 ( , ) Leaf leading edge insertion point E0 n ( , ) The average setting is between the blade trailing edge bend endpoint C0 and the blade trailing edge point D0. m The visual coordinates of each point are as follows: Leaf trailing edge insertion point F0 m ( , ) Leaf trailing edge insertion point F0 m-1 ( , ) … Leaf trailing edge insertion point F02 ( , ) Leaf trailing edge insertion point F01 ( , ); The specific operation for generating the robot coordinates of the blade tip additive welding feature points in step 6 is as follows: The welding actuator is operated to adjust the welding torch to be perpendicular to the blade tip, the welding torch nozzle contacts the blade tip surface, and the Z-axis coordinate is read and defined as... The visual coordinates read in step 5 are converted into robot coordinates to obtain the planar coordinates of the blade tip feature points. The Z-axis coordinates of the blade tip are then converted. The following values ​​are assigned to obtain the three-dimensional coordinates of the blade tip feature point manipulator: A0, the leading edge point of the blade ( , , ) Leaf leading edge insertion point E01 ( , , ) Leaf leading edge insertion point E02 ( , , ) … Leaf leading edge insertion point E0 n-1 ( , , ) Leaf leading edge insertion point E0 n ( , , ) The end point of the positive bend at the leading edge of the blade is B0 ( , , ) The end point of the blade trailing edge recurve C0 ( , , ) Leaf trailing edge insertion point F0 m ( , ) Leaf trailing edge insertion point F0 m-1 ( , , ) … Leaf trailing edge insertion point F02 ( , ) Leaf trailing edge insertion point F01 ( , ) trailing edge point D0 ( , ); The specific operation for converting the feature points of the blade tip additive welding trajectory in step 7 is as follows: the blade leading edge positive bending trajectory planning comprehensively considers the welding gun distance. Angle of positive curvature at the leading edge Angle between the leading edge and the leaf tip Calculate the coordinates of feature points for the leading-edge positive bending welding trajectory planning; comprehensively consider the welding gun distance for the trailing-edge negative bending trajectory planning. trailing edge reverse bend angle Angle between the trailing edge and the leaf tip Calculate the coordinates of the feature points for the trailing edge reverse bending welding trajectory planning; q The formula for calculating the coordinates of feature points required for weld seam trajectory planning is as follows: A1（ ， ） E1（ ， ） E2（ ， ） …… E1 n-1 （ ， ） E1 n （ ， ） B1（ ， ， ） C1（ ， ， ） F1 m （ ， ） F1 m-1 （ ， ） … F12（ ， ） F11（ ， ） D1（ ， ） Based on the calculation formula, the coordinates of the feature points required for the first weld seam trajectory planning are obtained: A1（ ， ） E1（ ， ） E2（ ， ） …… E1 n-1 （ ， ） E1 n （ ， ） B1（ ， ， ） C1（ ， ， ） F1 m （ ， ） F1 m-1 （ ， ） … F12（ ， ） F11（ ， ） D1（ ， ） Based on the calculation formula, the coordinates of the feature points required for the second weld seam trajectory planning are obtained: A1（ ， ） E1（ ， ） E2（ ， ） …… E1 n-1 （ ， ） E1 n （ ， ） B1（ ， ， ） C1（ ， ， ） F1 m （ ， ） F1 m-1 （ ， ） … F12（ ， ） F11（ ， ） D1（ ， ） Based on the calculation formula, the first... p Coordinates of feature points required for weld seam trajectory planning: A1（ ， ） E1（ ， ） E2（ ， ） …… E1 n-1 （ ， ） E1 n （ ， ） B1（ ， ， ） C1（ ， ， ） F1 m （ ， ） F1 m-1 （ ， ） … F12（ ， ） F11（ ， ） D1（ ， ）。 2. The 3D design method for additive welding trajectory planning of aero-engine rotor blade tips according to claim 1, characterized in that: The specific operation of the pre-welding processing of the damaged blade tip in step 1 is as follows: the blade tip is machined and polished to achieve a surface roughness of Ra0.1 to 0.05, and the blade tip surface is perpendicular to the central axis of the blade after polishing.

3. The 3D design method for additive welding trajectory planning of aero-engine rotor blade tips according to claim 1, characterized in that: The specific operation of the three-dimensional scanning of the damaged leaf shape in step 2 is as follows: the leaf surface is thoroughly cleaned with an organic solvent to prevent oil and impurities adhering to the surface from affecting the acquisition accuracy; the damaged leaf is measured using a three-dimensional optical scanning device; to improve the scanning accuracy, a thin layer of imaging agent is sprayed onto the leaf surface to obtain the leaf point cloud; and the error point cloud is removed using a smoothing filter method.

4. The 3D design method for additive welding trajectory planning of aero-engine rotor blade tips according to claim 1, characterized in that, The specific operation for generating the blade tip additive welding trajectory in step 8 is as follows: set the motion trajectory between adjacent feature points of each weld seam in the blade tip additive welding to be a straight line, set the motion speed between adjacent feature points, and obtain the 3D design of the aero-engine rotor blade additive welding trajectory.

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