A welding method based on a groove reconstruction strategy

Abstract

The present application relates to a kind of welding methods based on groove reconstruction strategy, process pipeline is used for installation on the rotary table of positioner, welding robot is electrically connected with controller by control device, positioner is electrically connected with controller, tracking sensor is arranged at the end of the mechanical arm of welding robot, and is fixedly connected with welding torch on welding robot, tracking sensor is electrically connected with controller;Welding method: the groove of process pipeline is reconstructed by controller;Through controller, multi-layer multi-pass welding is planned;The groove of process pipeline is carried out backing welding;After backing welding is completed, the groove of process pipeline is carried out multi-layer multi-pass welding;Through groove reconstruction, the influence of process pipeline coaxiality error, ovality error, groove cutting error and installation error on welding quality is better reduced between weld section and laser plane feature point conversion, and the influence of pipeline thermal deformation on welding quality in welding process is simultaneously solved, and welding precision and weld quality are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a welding method based on a groove reconstruction strategy. BACKGROUND

[0002] At present, the visual tracking of the multi-layer multi-pass welding of the process pipeline welding robot mainly focuses on the identification of the first welding seam, and the subsequent welding position is mainly realized by using the offset strategy to control the welding process of the robot, which results in low welding precision and poor welding seam quality. SUMMARY

[0003] In view of the defects in the prior art, the present application aims to provide a welding method based on a groove reconstruction strategy, which has the advantages of improving the welding precision and the welding seam quality.

[0004] The above application of the present application is realized by the following technical scheme: a welding method based on a groove reconstruction strategy, a welding system is used for groove welding of a process pipeline, the welding system comprises a welding robot, a control device, a controller, a tracking sensor and a positioner, the process pipeline is used for being installed on a rotary table of the positioner, the rotary table can drive the process pipeline to rotate, the welding robot is electrically connected with the controller through the control device, the positioner is electrically connected with the controller, the tracking sensor is arranged at the end of the mechanical arm of the welding robot and is fixedly connected with a welding torch on the welding robot to constitute a hand-eye calibration, and the tracking sensor is electrically connected with the controller.

[0005] The welding method comprises the following steps:

[0006] reconstructing the groove of the process pipeline through the controller;

[0007] planning the multi-layer multi-pass welding through the controller;

[0008] bottoming welding is performed on the groove of the process pipeline;

[0009] After the bottoming welding is completed, multi-layer multi-pass welding is performed on the groove of the process pipeline.

[0010] Preferably, the welding method based on the groove reconstruction strategy comprises the following steps:

[0011] clamping the process pipeline on the rotary table of the positioner;

[0012] the welding seam image of the process pipeline is displayed in the image of the tracking sensor;

[0013] The weld section feature points are converted to the welding gun section feature points to obtain the actual bevel feature points of the weld section.

[0014] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention, wherein converting the weld cross-sectional feature points to the welding torch cross-sectional feature points to obtain the actual bevel feature points of the weld cross-section, includes:

[0015] Extract the coordinates of three feature points P1, P2, and P3 from the weld images at various locations on the process pipeline, and transform the coordinates of all feature points to the robot base coordinate system. B P i ;

[0016] Calculate the plane Π containing the characteristic points of each set of bevels on the process pipeline. i ;

[0017] Calculate angles β1, β2, and β3 in sequence;

[0018] The calculation formulas for the actual bevel characteristic points of each weld section are as follows:

[0019] P iw =Rot( C Z P ,β i )P ic

[0020] Where: P iw Rot( represents the actual bevel feature point of the weld section). C Z p ,β i ) for the Z-shaped positioner p Axis rotation angle rotation operator, P ic The coordinate system Y of the feature point to the welding torch T O T Z T Determine the point by plane distance.

[0021] Preferably, in the welding method based on bevel reconstruction strategy provided by the present invention, the coordinate transformation relationship of the three feature points on the weld image is as follows:

[0022]

[0023] Where: M in The camera intrinsic parameter matrix in the tracking sensor is obtained through the intrinsic parameter calibration of the tracking sensor. C T T The 4×4 hand-eye calibration inverse matrix is ​​obtained through hand-eye calibration. T T B The transformation matrix of the welding torch relative to the robot's base coordinate system is obtained through welding torch calibration; (u i vi ) T and (x) i y i z i ) T These represent the pixel coordinates of the three feature points relative to the robot's base coordinate system. B P1, B P2, B P3.

[0024] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention involves calculating the plane Π where each set of bevel feature points on the process pipeline is located. i ,include:

[0025] The coordinates of each set of feature points are generated in the robot's base coordinate system based on the rotation angle of the positioner. B P i (j);

[0026] The coordinates of each set of feature points are transformed to the camera coordinate system of the tracking sensor to obtain... C P i (j);

[0027] The Ransac method is used in the camera coordinate system. C P i (j) Fits the plane Π to point. i .

[0028] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention, B P i (j) = Rot( B Z p ,θ j )P i (j)

[0029] Among them, Rot( B Z p θ j ) for the Z-shaped positioner p Axis rotation angle rotation operator, bevel feature points {P1(j), P2(j), P3(j)}, where j is the measurement point number, θ j This refers to the rotation angle of the positioner.

[0030] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention, wherein the sequential calculation of angles β1, β2, and β3 includes:

[0031] The first set of points, denoted as P, is acquired by combining the weld seam image. 1a P 2a P 3a ;

[0032] Calculate the distance between the rotation axis of the positioner and the plane Πi of each feature point, and determine point P. 1b P 2b P 3b ;

[0033] Calculate the Y coordinate system of each feature point from the welding torch. T O T Z T Determine the plane distance to point P 1c P2 c P 3c ;

[0034] Calculate ∠P sequentially 1a P 1b P 1c ,∠P 2a P 2b P 2c ,∠P 3a P 3b P 3c .

[0035] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention, wherein the planning of multi-layer, multi-pass welding by the controller includes:

[0036] Based on the welding experiment results, determine the rotational speed ω and wire feed speed wfs corresponding to the process pipeline, and determine the corresponding welding current, weld bead, and number of weld layers.

[0037] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention includes, in the step of performing root pass welding on the bevel of the process pipeline, the following steps:

[0038] The positioner drives the process pipeline to rotate around the Z-axis of the positioner. P The shaft rotates in the opposite direction. The control device, based on the real-time rotation angle of the positioner, obtains feature points through weld image processing and uses the bevel reconstruction to obtain β. i Calculate the actual shape characteristic point P of the weld section. iw .

[0039] Preferably, the welding method based on bevel reconstruction strategy provided by the present invention includes, after the root pass welding is completed, multi-layer, multi-pass welding of the bevel of the process pipeline, comprising:

[0040] The laser stripes on the weld image are skeletonized, and the coordinates of the pixels representing the laser stripes are fitted with cubic curves using the least squares method.

[0041] Calculate the average weld height of the corresponding weld layer, and obtain the second derivative of the cubic curve. Search for the inflection point of the curve and determine whether to retain the inflection point in combination with the number of weld layers. Then, use the retained inflection point as the position of the subsequent weld bead to plan the position of multiple layers and multiple passes of weld bead.

[0042] Based on the groove reconstruction, the coordinates of the laser planar multi-layer multi-pass welding path points are transformed into the weld cross section.

[0043] In summary, the beneficial technical effects of this invention are as follows: The welding method based on bevel reconstruction strategy provided in this application uses a welding system for bevel welding of process pipelines. The welding system includes a welding robot, a control device, a controller, a tracking sensor, and a positioner. The process pipeline is mounted on the turntable of the positioner, which can drive the process pipeline to rotate. The welding robot is electrically connected to the controller via the control device, and the positioner is electrically connected to the controller. The tracking sensor is located at the end of the robotic arm of the welding robot and is fixedly connected to the welding torch on the welding robot to form a hand-eye calibration. The tracking sensor is electrically connected to the controller. The welding method includes the following steps: reconstructing the bevel of the process pipeline using the controller; planning multi-layer, multi-pass welding using the controller; performing root pass welding on the bevel of the process pipeline; and after the root pass welding is completed... The process piping is beveled using multi-layer, multi-pass welding. This approach offers several advantages. First, compared to traditional V-groove multi-layer, multi-pass welding where weld layers and passes are often planned using ideal geometric shapes instead of single-pass weld shapes, this application eliminates the need for unnecessary simplification of weld shapes when controlling a welding robot for automated welding of process piping. It only requires pre-planning the weld cross-section contour and more accurately selecting welding cross-section feature points based on the weld contour shape, thus improving welding position selection. Second, bevel reconstruction allows for better reduction of the impact of process piping coaxiality errors, ellipticity errors, bevel cutting errors, and installation errors on welding quality through the conversion between the weld cross-section and laser plane feature points. It also addresses the impact of pipe thermal deformation during welding, improving welding accuracy and weld quality. Attached Figure Description

[0044] Fig. 1 This is a flowchart of a welding method based on a bevel reconstruction strategy provided in an embodiment of the present invention.

[0045] Fig. 2 This is a schematic diagram of the overall structure of the welding system in the welding method based on the bevel reconstruction strategy provided in the embodiment of the present invention.

[0046] Fig. 3 This refers to the coordinate calibration of the welding robot, tracking sensor, positioner, and process pipeline in the welding method based on bevel reconstruction strategy provided in this embodiment of the invention.

[0047] Fig. 4This is a schematic diagram of the coordinates P1, P2, and P3 on the weld bevel in the welding method based on the bevel reconstruction strategy provided in this embodiment of the invention.

[0048] Fig. 5 This refers to the method for determining the Y-axis of the welding torch coordinate system {T} in the welding method based on bevel reconstruction strategy provided in this embodiment of the invention. T O T Z T Plane, feature point plane Π i And images of laser weld seams.

[0049] Fig. 6 In the welding method based on bevel reconstruction strategy provided in this embodiment of the invention, point P is determined. 1c P2 c P 3c P 1b P 2b P 3b and P 1a P 2a P 3a .

[0050] Fig. 7 This invention relates to the welding method based on bevel reconstruction strategy, which determines the Z-direction of the welding torch for the root pass. T axis.

[0051] In the diagram, 1 is the welding system; 10 is the welding robot; 11 is the base; 12 is the robotic arm; 13 is the welding torch; 20 is the control device; 30 is the controller; 40 is the tracking sensor; 50 is the positioner; and 2 is the process piping. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the accompanying drawings.

[0053] Reference Figs. 1 to 3 This invention discloses a welding method based on a bevel reconstruction strategy. The welding system 1 is used for bevel welding of a process pipe 2. The welding system 1 includes a welding robot 10, a control device 20, a controller 30, a tracking sensor 40, and a positioner 50. The process pipe 2 is installed on the turntable of the positioner 50. The turntable can drive the process pipe 2 to rotate. The welding robot 10 is electrically connected to the controller 30 through the control device 20. The positioner 50 is electrically connected to the controller 30. The tracking sensor 40 is set at the end of the robotic arm 12 of the welding robot 10 and is fixedly connected to the welding torch 13 on the welding robot 10 to form a hand-eye calibration. The tracking sensor 40 is electrically connected to the controller 30.

[0054] The welding process of the welding robot 10 is controlled by eye-in-hand calibration.

[0055] Specifically, the welding robot 10 includes a base 11, a robotic arm 12, and a welding torch 13. The bottom end of the robotic arm 12 is connected to the top surface of the base 11, and the welding torch 13 is located at the end of the robotic arm 12.

[0056] For example, the controller 30 can be a computer; of course, the controller 30 can also be a handheld device. In the implementation where the controller 30 is a computer, control functions such as image processing, bevel reconstruction (i.e., initial welding position reconstruction), welding process planning, and multi-layer multi-pass welding path point selection are all performed by the computer, which then transmits the data required by the welding robot 10 to the control device 20.

[0057] During the welding process, the positioner 50 can drive the process pipeline 2 to move at a constant speed, and cooperate with the welding robot 10 to complete the automatic welding work; or the welding robot 10 can perform segmented all-position welding. After each stage of welding is completed, the positioner 50 adjusts the angle of the process pipeline 2 to perform the next stage of welding.

[0058] The welding method includes the following steps:

[0059] S101. The bevel of the process pipeline 2 is reconstructed by the controller 30. Thus, by converting between the weld section and the laser plane feature points, the influence of the coaxiality error, ellipticity error, bevel cutting error and installation error of the process pipeline 2 on the welding quality is better reduced. At the same time, the influence of pipeline thermal deformation on the welding quality during the welding process is solved, thereby improving the welding accuracy and weld quality.

[0060] Furthermore, in this embodiment, S101, reconstructing the beveling of the process pipeline 2 via the controller 30, includes:

[0061] S1011. Clamp the process pipe 2 onto the turntable of the positioner 50.

[0062] Specifically, the process pipe 2 is clamped on the turntable of the positioner 50, and the fixture on the turntable automatically clamps the process pipe 2.

[0063] The weld image of process pipe 2 (S1012) is displayed in the image of tracking sensor 40.

[0064] In the tracking control process of the weld seam in process pipeline 2, the coordinate systems and their transformation relationships are as follows: the welding robot 10 involves three coordinate systems: the base 11 coordinate system {B}, the wrist coordinate system {E} of the robotic arm 12 (i.e., the coordinate system of the 6th link of the welding robot 10), and the welding torch 13 coordinate system {T}; the tracking sensor 40 is installed at the end of the robotic arm 12 and fixed to the welding torch 13 to form an eye-in-hand calibration, and the coordinate system of the tracking sensor 40 is denoted as {C}; the positioner 50 coordinate system is denoted as {P}, and the Z-axis of the positioner 50 coordinate system is defined.p The axis is the direction of the rotation axis of the positioner 50.

[0065] In this embodiment, the transformation relationship between the wrist coordinate system and the base 11 coordinate system is denoted as: B T E The welding robot can be reset at the origin (10); the transformation relationship between the welding torch (13) coordinate system and the base coordinate system is denoted as... B T T The position of the tracking sensor in coordinate system 40 relative to the welding torch 13 can be determined by calibration; the position of the tracking sensor in coordinate system 40 relative to the welding torch 13 remains unchanged, denoted as... T T C The transformation relationship of the laser strip on the image in the base coordinate system {B} can be obtained through hand-eye calibration and laser plane calibration; the transformation relationship of the positioner's 50 coordinate system {P} relative to the base 11 can be obtained through the three-point teaching method calibration. B T P .

[0066] Specifically, the welding torch 13 on the welding robot 10 is controlled to approach the weld seam on the process pipe 2, so that the weld seam image is displayed in the image of the tracking sensor 40, and the welding torch 13 on the welding robot 10 is positioned directly above the rotation axis of the positioner 50, and the central axis of the welding torch 13 (i.e., Z) is... T The axis is aligned with the direction of gravity.

[0067] S1013. Convert the weld section feature points to the weld gun 13 section feature points to obtain the actual weld bevel feature points.

[0068] Continue to refer to Figs. 4 to 6 In this embodiment, S1013, converting the weld cross-section feature points to the weld gun 13 cross-section feature points to obtain the actual weld cross-section bevel feature points, includes:

[0069] S10131. Extract the coordinates of three feature points P1, P2, and P3 from the weld images at various locations on process piping 2, and transform the coordinates of all feature points to the robot base coordinate system. B P i .

[0070] Specifically, the turntable of the positioner 50 is controlled to rotate at a constant speed for one revolution, and the positions of each feature point of the weld image of the process pipeline 2 obtained by image processing on the controller 30 (i.e., the computer) are matched with the rotation angle of the positioner 50 and recorded.

[0071] During the rotation of the process pipeline 2, the welding torch 13 is always kept perpendicular to the ground. Then, the pixel coordinates obtained by the camera in the tracking sensor 40 are converted to the robot coordinate system according to the camera calibration, hand-eye calibration and laser plane calibration results.

[0072] Furthermore, in this embodiment, the coordinate transformation relationship of the three feature points on a single V-groove weld image is as follows:

[0073] In equation (1), M in The camera intrinsic parameter matrix in the tracking sensor 40 is obtained through the tracking sensor 40 intrinsic parameter calibration. C T T The 4×4 hand-eye calibration inverse matrix is ​​obtained through hand-eye calibration. T T B The transformation matrix of welding torch 13 relative to the robot base coordinate system is obtained through the calibration of welding torch 13; (u i v i ) T and (x) i y i z i ) T These represent the pixel coordinates of the three feature points relative to the robot's base coordinate system. B P1, B P2, B P3.

[0074] It should be noted that points P1 and P3 are the two outer contour points of the V-shaped bevel, and point P2 is the welding path point of the welding position.

[0075] This yields N sets of V-groove feature points {P1(j), P2(j), P3(j)}, where N is the total number of weld images, determined by the 40 frame rate of the tracking sensor, and j is the measurement point number and the rotation angle θ of the positioner 50. j correspond.

[0076] in,

[0077] In equation (2), ω is the angular velocity of the positioner at 50° rotation, and n is the camera frame rate.

[0078] S10132, Calculate the plane Π where the characteristic points of each group of bevels on process pipeline 2 are located. i .

[0079] Further, in this embodiment, S10132, the plane Π containing each set of bevel feature points on the process pipeline 2 is calculated. i ,include:

[0080] S101321. The coordinates of each set of feature points are generated in the robot base coordinate system based on the rotation angle of the positioner 50. B P i (j).

[0081] Specifically, due to the image coordinates P captured during the image acquisition process iThis is based on the premise that the welding torch 13 remains stationary. Therefore, it is necessary to combine the calculated three sets of points P1, P2, and P3 with the positioner's 50° rotation angle θ. j Correspondence. Where θ j The rotation angle of process pipeline 2 can be read by the encoder of positioner 50, and the coordinates of all feature points are transformed to the base coordinate system {B}. The full circle data in the base coordinate system is generated based on the rotation angle of positioner 50.

[0082] Right now B P i (j) = Rot( B Z p ,θ j )P i (j) (3)

[0083] In equation (3), Rot( B Z p θ j ) is the 50Z positioner p Axis rotation angle rotation operator, bevel feature points {P1(j), P2(j), P3(j)}, where j is the measurement point number, θ j This refers to the rotation angle of positioner 50.

[0084] S101322, Transform the coordinates of each set of feature points to the camera coordinate system in the tracking sensor 40 to obtain... C P i (j).

[0085] Specifically, adopting the formula C P i (j)= C T B B P i (j) Transform the three sets of feature points P1, P2, and P3 into the camera coordinate system {C} to obtain... C P i (j).

[0086] S101323, Using the Ransac method in the camera coordinate system C P i (j) Fit the plane Πi to point.

[0087] Specifically, the Ransac method is used in the camera coordinate system. C P1, C P2 and C P3 is a set of three points that fit together to form three planes, denoted as Π1, Π2 and Π3.

[0088] Π1:A1x+B1y+C1z+D1=0

[0089] ∏2:A2x+B2y+C2z+D2=0 (4)

[0090] ∏3:A3x+B3y+C3z+D3=0

[0091] S10133. Calculate angles β1, β2, and β3 in sequence.

[0092] Further, in this embodiment, S10133, calculating angles β1, β2, and β3 sequentially, includes:

[0093] S101331, Combine the weld seam image to collect the first group of points, denoted as P. 1a P 2a P 3a .

[0094] Specifically, feature points C P i They are projected onto their respective planes.

[0095] C P Πi = C P i +u i t i In the formula C P Πi To obtain a series of V-shaped bevel profile points on the corresponding fitted plane Π i The projection onto the surface, where i is 1, 2, 3, corresponding to point P. i Sequence, u i Let t be the direction vector of each of the three planes. i Let t be the parameter of the equation of the perpendicular line from a point to a plane. i It can be calculated using the following formula:

[0096]

[0097] In formula (5) C P i0 For any one that is exactly in Π i For a point on a plane, that is, a point whose distance from the plane is 0, since the Ransac method is used to fit the contour points in the plane, there must exist at least one point that satisfies the condition that the point is in the plane.

[0098] The calculated groups C P Πi The first point in the array is denoted as P. 1a P 2a P 3a .

[0099] S101332. Calculate the distance between the rotation axis of the positioner 50 and the plane Πi of each feature point, and determine point P. 1bP 2b P 3b .

[0100] Specifically, the rotation axis Z of the positioner is calculated in the camera coordinate system {C}. p The points where the axis intersects the three planes Π1, Π2, and Π3 are denoted as P. 1b P 2b P 3b .

[0101] S101333, Calculate the Y coordinate system from each feature point to the welding torch 13 coordinate system. T O T Z T Determine the plane distance to point P 1c P 2c P 3c .

[0102] Specifically, calculate separately C P Πi From the contour points of each bevel and the characteristic points of the weld to the Y-coordinate system of the welding torch (13 coordinate system) T O T Z T Planar distance.

[0103]

[0104] The weld plane Π T The equation is A T C x Πi +B T C y Πi +C T C z Πi +D T =0 (that is, the Y coordinate of the welding torch 13 coordinate system) T O T Z T Plane). A T B T C T For Y T O T Z T The plane normal direction, which is the X-axis of the welding torch 13 coordinate system {T}. T Axial direction, D T It can be determined from the origin O of the 13 coordinate system of the welding torch. T get.

[0105] In formula (6) C x Πi , C y Πi , C zΠi For point C P Πi coordinate.

[0106] Three out-of-plane Π are obtained from the three sets of points. T The nearest points are denoted as P. 1c P 2c P 3c And record the corresponding point number j.

[0107] S101334, calculate ∠P sequentially. 1a P 1b P 1c ,∠P 2a P 2b P 2c ,∠P 3a P 3b P 3c Let them be β1, β2, β3.

[0108] S10134. The calculation formula for the actual bevel characteristic points of each weld section is as follows:

[0109] P iw =Rot( C Z P ,β i )P ic

[0110] Where: P iw Rot( represents the actual bevel feature point of the weld section). C Z p ,β i ) is the 50Z positioner p Axis rotation angle rotation operator, P ic For the feature point to the welding torch 13 coordinate system Y T O T Z T Determine the point by plane distance.

[0111] Specifically, based on the calculation formula for the actual bevel characteristic points of each weld section:

[0112] P iw =Rot( C Z P ,β i )P ic (7)

[0113] Continuously calculate the actual groove feature points P of each weld section 1w P 2w and P 3w .

[0114] It should be noted that the above calculations were all performed in the camera coordinate system.

[0115] Finally, through coordinate transformation, the actual slope feature points calculated in the camera coordinate system are transformed to the base coordinate system.

[0116] S102, The controller 30 is used to plan the multi-layer multi-pass welding.

[0117] Furthermore, in this embodiment, S102, the controller 30 plans the multi-layer multi-pass welding, including: determining the rotational speed ω and wire feeding speed wfs of the corresponding process pipeline 2 based on the welding experiment results, and determining the corresponding welding current, weld pass and number of weld layers.

[0118] Specifically, based on the actual shape characteristic point P of the V-groove of each weld section... 1w P 2w and P 3w The weld layer height is determined based on the welding process. This height can be obtained through welding process experiments, and efforts should be made to ensure that welding process parameters remain constant throughout the subsequent weld layers and weld passes. Assuming the expected number of weld layers is Nc, the actual number of weld passes Np is:

[0119]

[0120] Although the actual shape of each weld bevel may have errors, the theoretical bevel shape can be used for planning, considering the subsequent cover weld. Assuming the theoretical bevel angle is α and the bevel height is H, the bevel cross-sectional area Sv can be obtained from the following formula:

[0121]

[0122] The cross-sectional area Sp of a single weld bead is:

[0123]

[0124] Based on the welding experiment results, the corresponding pipe rotation speed ω and wire feed speed wfs are determined. S103, Perform root pass welding on the bevel of process pipe 2.

[0125] Continue to refer to Figs. 4 to 7 In this embodiment, S103, performing root pass welding on the bevel of the process pipe 2, includes: the positioner 50 driving the process pipe 2 around the Z-axis of the positioner 50. P The shaft rotates in the opposite direction. The control device 20, based on the real-time rotation angle of the positioner 50, obtains feature points through weld image processing and uses bevel reconstruction to obtain β. i Calculate the actual shape characteristic point P of the weld section. iw .

[0126] Specifically, during the root pass welding stage, the positioner 50 drives the process piping 2 around Z. PThe shaft rotates in the opposite direction. The control device 20, based on the real-time rotation angle θ of the positioner 50, obtains three sets of points P1, P2, and P3 through weld seam image processing. β is obtained using the aforementioned bevel reconstruction. i Calculate the characteristic point P of the actual shape of the V-groove of the weld section. 1w P 2w and P 3w .

[0127] During the root pass welding, the direction of the V-groove angle bisector is calculated based on the obtained weld feature points to determine the Z-direction of the welding torch 13. T axis.

[0128] Specifically, to ensure welding quality, the welding torch 13Z needs to be guaranteed. T The axial direction is in the weld plane Π T On the bisector of the bevel angle of the process pipeline 2. Point P. 2w The origin of the actual weld groove section coordinate system is given by the direction vector P. 2w P 1w The X-axis direction is the coordinate system of the weld bevel section, and the X-axis direction is the coordinate system of the welding torch 13. T The axial direction is taken as the Z-axis direction of the weld groove section coordinate system. First, ∠P is calculated based on the coordinates of the three points. 1w P 2w P 3w Then, the Z coordinate system of the welding torch 13 is obtained by using the rotation formula around the axis. T The axis direction is then transformed to the base coordinate system.

[0129] All welding sections can be pre-planned based on the reconstruction process data, thereby enabling automatic welding of the root pass of process piping 2.

[0130] S104. After the root pass welding is completed, the bevel of process pipe 2 is subjected to multi-layer, multi-pass welding.

[0131] Specifically, in the subsequent welds after the root pass, the above-mentioned bevel reconstruction is still used. The difference is that the number of feature points changes accordingly as the number of weld layers increases.

[0132] Furthermore, in this embodiment, after the root pass welding in step S104, the bevel of the process pipe 2 is subjected to multi-layer, multi-pass welding, including:

[0133] S1041. Skeletonize the laser stripes on the weld image, and perform cubic curve fitting on the pixel coordinates representing the laser stripes using the least squares method.

[0134] Specifically, the laser stripes on the weld seam tracking image are first skeletonized, and then the pixel coordinates representing the laser stripes are fitted with cubic curves using the least squares method.

[0135] v = a3u 3 +a2u 2 +a1u+a0

[0136] S1042. Calculate the average weld height of the corresponding weld layer, and obtain the second derivative of the cubic curve. Search for the inflection point of the curve and determine whether to retain the inflection point in combination with the number of weld layers. Then, use the retained inflection point as the position of subsequent weld layers to plan the position of multiple layers and multiple passes of weld.

[0137] S1043. Based on the bevel reconstruction, perform the conversion of the coordinates of the laser planar multi-layer multi-pass welding path points in the weld section.

[0138] The welding method based on bevel reconstruction strategy provided in this application includes a welding system 1 for bevel welding of a process pipe 2. The welding system 1 includes a welding robot 10, a control device 20, a controller 30, a tracking sensor 40, and a positioner 50. The process pipe 2 is mounted on the turntable of the positioner 50, which can drive the process pipe 2 to rotate. The welding robot 10 is electrically connected to the controller 30 via the control device 20, and the positioner 50 is also electrically connected to the controller 30. The tracking sensor 40 is located at the end of the robotic arm 12 of the welding robot 10 and is fixedly connected to the welding torch 13 on the welding robot 10 to form a hand-eye calibration. The tracking sensor 40 is electrically connected to the controller 30. The welding method includes the following steps: reconstructing the bevel of the process pipe 2 through the controller 30; planning multi-layer multi-pass welding through the controller 30; and reconstructing the bevel of the process pipe 2. The root pass welding is performed. After the root pass welding is completed, the bevel of the process pipe 2 is welded in multiple layers and multiple passes. With this setup, on the one hand, compared with the traditional V-groove multi-layer and multi-pass welding, where the weld layer and weld pass planning often uses ideal geometric shapes to replace the shape of a single weld, this application does not need to unnecessarily simplify the shape of each weld when the welding robot 10 is automatically welding the process pipe 2. It only needs to pre-define the weld cross-section outline and select the feature points of the welding cross-section more accurately through the weld outline shape, thereby making better selection of the welding position. On the other hand, through bevel reconstruction, the conversion between the weld cross-section and the laser plane feature points can better reduce the impact of the coaxiality error, ellipticity error, bevel cutting error and installation error of the process pipe 2 on the welding quality, and at the same time solve the impact of pipe thermal deformation on the welding quality during the welding process, thereby improving the welding accuracy and weld quality.

[0139] The welding method based on bevel reconstruction strategy provided by this invention has the following advantages: by converting between the weld cross section and the laser plane feature points, it can better reduce the impact of coaxiality error, ellipticity error, bevel cutting error and installation error of the process pipeline 2 on the welding quality, and at the same time solve the impact of pipeline thermal deformation on the welding quality during the welding process.

[0140] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0141] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A welding method based on a groove reconstruction strategy, characterized in that: The welding system is used for welding the groove of a process pipeline, and comprises a welding robot, a control device, a controller, a tracking sensor and a positioner. The process pipeline is installed on a rotary table of the positioner, and the rotary table can drive the process pipeline to rotate. The welding robot is electrically connected with the control device and the controller. The positioner is electrically connected with the controller. The tracking sensor is arranged at the end of a mechanical arm of the welding robot and is fixedly connected with a welding torch on the welding robot to form a hand-eye calibration. The tracking sensor is electrically connected with the controller. The welding method comprises the following steps: reconstructing the groove of the process pipeline by the controller; planning multi-layer and multi-pass welding by the controller; preliminary welding of the groove of the process pipeline; after the preliminary welding is completed, multi-layer and multi-pass welding of the groove of the process pipeline is performed; the reconstruction of the groove of the process pipeline by the controller comprises: clamping the process pipeline on the rotary table of the positioner; displaying the weld seam image of the process pipeline in the image of the tracking sensor; converting the weld seam cross-section feature points to the welding torch cross-section feature points to obtain the actual groove feature points of the weld seam cross-section; the conversion of the weld seam cross-section feature points to the welding torch cross-section feature points to obtain the actual groove feature points of the weld seam cross-section comprises: Three feature points P1, P2 and P3 on the weld image at each position of the process pipeline are extracted, and the coordinates of all the feature points are converted to the robot base coordinate system to obtain B P i ; calculating a plane Π on which each group of bevel feature points on the process pipeline is located i ; sequentially calculating angles β1, β2 and β3; the calculation formula of each actual groove feature point of the weld seam cross-section is: ( C Z P , )P ic wherein: is the actual bevel feature point of the weld cross section, Rot C Z p , is the rotation operator around the rotation angle of the positioner Z p axis, P ic is the feature point to the weld gun coordinate system Y T O T Z T plane distance determination point; the coordinate conversion relationship of the three feature points on the weld seam image is: wherein: M in is a camera intrinsic matrix in the tracking sensor obtained by tracking sensor intrinsic calibration, C T T is a 4x4 hand-eye calibration inverse matrix obtained by hand-eye calibration, T T B is a welding gun relative to robot base coordinate system conversion matrix obtained by welding gun calibration;(u i , v i ) T and (x i , y i , z i ) T respectively represent three feature point pixel coordinates relative to robot base coordinates B P1, B P2, B P3. calculating planes Π in which each group of bevel feature points on the process pipeline is located i comprising: The coordinates of the feature points in each group are generated into a robot base coordinate system according to the rotation angle of the positioner B P i (j); Converting each set of feature point coordinates into a camera coordinate system of the tracking sensor results in C P i (j); using the Ransac method in the camera coordinate system C P i (j) fitting a plane Π i ; where Rot B Z p , ) is the rotation operator around the rotation axis of the displacement machine Z p , the bevel feature points {P1(j), P2(j), P3(j)} and j is the serial number of the measuring point, θ j is the rotation angle of the displacement machine. the sequential calculation of the angles β1, β2 and β3 comprises: The first group of points of the weld joint image is recorded as P 1a , P 2a , P 3a ; calculating the distance between the rotation axis of the roll and each feature point plane Pi, determining point P 1b , P 2b , P 3b ; Calculate the distance from each feature point to the welding torch coordinate system Y T O T Z T Determine the distance of the plane to the point P 1c , P 2 c , P 3c ; P 1a P 1b P 1c P 2a P 2b P 2c P 3a P 3b P 3c P 2. The groove reconstruction strategy based welding method of claim 1, wherein: the planning of the multi-layer and multi-pass welding by the controller comprises: determining the rotational speed ω and the wire feeding speed wfs corresponding to the process pipeline according to the welding experimental results, and determining the corresponding welding current, welding pass and number of welding layers.

3. The groove reconstruction strategy based welding method of claim 1, wherein: the preliminary welding of the groove of the process pipeline comprises: The positioner drives the process pipeline around the Z P The control device obtains feature points by weld seam image processing according to the real-time rotation angle of the positioner, and calculates the actual shape feature points P of the weld seam section by using the slope reconstruction value . iw .

4. The groove reconstruction strategy based welding method of claim 1, wherein: after the preliminary welding is completed, the multi-layer and multi-pass welding of the groove of the process pipeline comprises: skeletonizing the laser stripe on the weld seam image, and performing cubic curve fitting on the obtained pixel point coordinates representing the laser stripe by using the least square method; calculating the average weld seam height corresponding to the welding layer, and calculating the second derivative of the cubic curve, searching for the inflection point of the curve and combining the number of welding layers to determine whether the inflection point is retained, and then taking the retained inflection point as the subsequent welding pass position to plan the multi-layer and multi-pass welding pass position; according to the groove reconstruction, the conversion of the laser plane multi-layer and multi-pass welding path point coordinates in the weld seam cross-section is performed.

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