Welding method based on groove reconstruction strategy

Abstract

The invention relates to a welding method based on a groove reconstruction strategy. A process pipeline is used for being installed on a rotary table of a positioner, a welding robot is electrically connected with a controller through a control device, the positioner is electrically connected with the controller, and a tracking sensor is arranged at the tail end of a mechanical arm of the welding robot and fixedly connected with a welding gun on the welding robot. The tracking sensor is electrically connected with the controller; the welding method comprises the steps that a groove of the process pipeline is reconstructed through the controller; the multi-layer and multi-pass welding is planned through the controller; backing welding is conducted on the groove of the process pipeline; after backing welding is completed, multi-layer and multi-pass welding is conducted on the groove of the process pipeline; through groove reconstruction and conversion between the weld joint section and the laser plane feature points, the influence of coaxiality errors, ovality errors, groove cutting errors and installation errors of the process pipeline on the welding quality is better reduced, meanwhile, the influence of pipeline thermal deformation on the welding quality in the welding process is solved, and the welding precision and the weld joint quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a welding method based on a groove reconstruction strategy. Background Art

[0002] At present, the visual tracking of multi-layer and multi-pass welding of process pipeline welding robots mainly focuses on the identification of the first weld, and the positions of subsequent welds mostly use an offset strategy to achieve robot welding process control, resulting in low welding accuracy and poor weld quality. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a welding method based on a groove reconstruction strategy, which has the advantage of being able to improve welding accuracy and weld quality.

[0004] The above-mentioned invention object of the present invention is achieved through the following technical solutions: a welding method based on groove reconstruction strategy, a welding system is used for groove 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 used to be installed on the turntable of the positioner, the turntable can drive the process pipeline to rotate, the welding robot is electrically connected to the controller through the control device, the positioner is electrically connected to the controller, the tracking sensor is arranged at the end of the mechanical arm of the welding robot, and is fixedly connected to the welding gun on the welding robot to form hand-eye calibration, and the tracking sensor is electrically connected to the controller;

[0005] Wherein, the welding method comprises the following steps:

[0006] reconstructing the groove of the process pipeline by means of the controller;

[0007] Planning multi-layer and multi-pass welding by means of the controller;

[0008] Performing base welding on the groove of the process pipeline;

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

[0010] Preferably, in the welding method based on groove reconstruction strategy provided by the present invention, the groove reconstruction of the process pipeline by the controller comprises:

[0011] Clamping the process pipeline on the turntable of the positioner;

[0012] The weld 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 groove feature points of the weld section.

[0014] Preferably, the welding method based on groove reconstruction strategy provided by the present invention, wherein the step of converting the weld cross-section feature points to the welding gun cross-section feature points to obtain the actual groove feature points of the weld cross-section comprises:

[0015] Extract the coordinates of three feature points P1, P2, and P3 on the weld image at each position of the process pipeline, and convert the coordinates of all feature points into the robot base coordinate system to obtain B P i ;

[0016] Calculate the plane Π of each group of groove feature points on the process pipeline i ;

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

[0018] The calculation formula for the actual groove characteristic points of each weld section is:

[0019] P iw =Rot( C Z P , β i ) ic

[0020] Where: P iw is the actual groove feature point of the weld section, Rot( C Z p , β i ) is the winding positioner Z p Axis rotation angle rotation operator, P ic Y coordinate system from feature point to welding gun T O T Z T Plane distance determination point.

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

[0022]

[0023] Where: M in The camera intrinsic parameter matrix in the tracking sensor is obtained by calibrating the intrinsic parameters of the tracking sensor. C T T is the 4×4 hand-eye calibration inverse matrix obtained through hand-eye calibration, T T B The welding gun relative to the robot base coordinate system transformation matrix is ​​obtained by welding gun calibration; (u i 、vi ) T and (x i ,y i 、z i ) T Represents the pixel coordinates of the three feature points relative to the robot base coordinate system B P1, B P2, B P3.

[0024] Preferably, the welding method based on groove reconstruction strategy provided by the present invention calculates the plane Π where each group of groove feature points on the process pipeline are located i ,include:

[0025] The coordinates of each set of feature points are generated according to the rotation angle of the positioner in the robot base coordinate system to obtain B P i (j);

[0026] The coordinates of each set of feature points are converted into 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) Point fitting out plane Π i .

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

[0029] Among them, Rot( B Z p ,θ j ) is the winding positioner Z p Axis rotation angle rotation operator, groove feature points {P1(j), P2(j), P3(j)}, j is the measurement point number, θ j is the turning angle of the positioner.

[0030] Preferably, the welding method based on groove reconstruction strategy provided by the present invention, wherein the angles β1, β2, and β3 are calculated in sequence, comprises:

[0031] Combined with the weld image acquisition, the first group of points is recorded as P 1a , P 2a , P 3a ;

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

[0033] Calculate each feature point to the welding gun coordinate system Y T O T Z T Plane distance determination point P 1c 、P2 c , P 3c ;

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

[0035] Preferably, the welding method based on groove reconstruction strategy provided by the present invention, wherein the controller is used to plan multi-layer and multi-pass welding, including:

[0036] The rotation speed ω and wire feeding speed wfs of the corresponding process pipeline are determined according to the welding test results, and the corresponding welding current, weld bead and number of weld layers are determined.

[0037] Preferably, the welding method based on the groove reconstruction strategy provided by the present invention, wherein the base welding is performed on the groove of the process pipeline, comprises:

[0038] The positioner drives the process pipeline to move around the Z direction of the positioner. P The axis rotates in the opposite direction, and the control device obtains feature points through weld image processing according to the real-time rotation angle of the positioner, and uses the β obtained by the groove reconstruction i The actual shape characteristic point P of the weld cross section is calculated by iw .

[0039] Preferably, in the welding method based on the groove reconstruction strategy provided by the present invention, after the base welding is completed, multi-layer and multi-pass welding is performed on the groove of the process pipeline, including:

[0040] The laser stripes on the weld image are skeletonized, and the pixel coordinates representing the laser stripes are obtained to perform cubic curve fitting using the least square method;

[0041] Calculate the average weld height of the corresponding weld layer, and find the second-order derivative of the cubic curve, search for the inflection point of the curve and determine whether the inflection point is retained in combination with the number of weld layers, and then use the retained inflection point as the subsequent weld bead position to plan the multi-layer and multi-pass weld bead position;

[0042] According to the groove reconstruction, the coordinates of the laser plane multi-layer multi-pass welding path points are converted in the weld cross section.

[0043] In summary, the beneficial technical effects of the present invention are as follows: the welding method based on the groove reconstruction strategy provided by the present application, the welding system is used for the groove welding of the process pipeline, the welding system includes a welding robot, a control device, a controller, a tracking sensor and a positioner, the process pipeline is used to be installed on the turntable of the positioner, the turntable can drive the process pipeline to rotate, the welding robot is electrically connected to the controller through the control device, the positioner is electrically connected to the controller, the tracking sensor is arranged at the end of the mechanical arm of the welding robot, and is fixedly connected to the welding gun on the welding robot to form a hand-eye calibration, and the tracking sensor is electrically connected to the controller; wherein the welding method includes the following steps: reconstructing the groove of the process pipeline by the controller; planning multi-layer and multi-pass welding by the controller; performing base welding on the groove of the process pipeline; after the base welding is completed, Multi-layer and multi-pass welding is performed on the groove of the process pipeline. With this arrangement, on the one hand, compared with the traditional V-groove multi-layer and multi-pass welding, the welding layer and weld planning mostly use ideal geometric figures instead of single-pass weld shapes. When the present application actually controls the welding robot to automatically weld the process pipeline, there is no need to unnecessarily simplify the shapes of each weld. It is only necessary to advance the weld cross-sectional contour and more accurately select the welding cross-sectional feature points through the weld contour shape, so as to better select the welding position; on the other hand, through groove reconstruction, the conversion between the weld cross section and the laser plane feature points can be used to better reduce the influence of the coaxiality error, ellipticity error, groove cutting error and installation error of the process pipeline on the welding quality, and at the same time solve the influence of pipeline thermal deformation on welding quality during welding, thereby improving welding accuracy and weld quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a welding method based on groove reconstruction strategy provided by an embodiment of the present invention.

[0045] Figure 2 It is a schematic diagram of the overall structure of a welding system in a welding method based on a groove reconstruction strategy provided in an embodiment of the present invention.

[0046] Figure 3 The invention relates to the coordinate calibration of a welding robot, a tracking sensor, a positioner and a process pipeline in a welding method based on a groove reconstruction strategy provided by an embodiment of the invention.

[0047] Figure 4It is a schematic diagram of the coordinates P1, P2, and P3 on the weld groove in the welding method based on the groove reconstruction strategy provided in an embodiment of the present invention.

[0048] Figure 5 Y is the coordinate system {T} of the welding gun in the welding method based on the groove reconstruction strategy provided by the embodiment of the present invention. T O T Z T Plane, feature point plane Π i and laser weld images.

[0049] Figure 6 The point P is determined in the welding method based on the groove reconstruction strategy provided by the embodiment of the present invention. 1c 、P2 c , P 3c , P 1b , P 2b , P 3b and P 1a , P 2a , P 3a .

[0050] Figure 7 The method for determining the direction Z of the welding gun for the base welding in the welding method based on the groove reconstruction strategy provided by the embodiment of the present invention is T axis.

[0051] In the figure, 1. welding system; 10. welding robot; 11. base; 12. robotic arm; 13. welding gun; 20. control device; 30. controller; 40. tracking sensor; 50. positioner; 2. process pipeline. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0053] Reference Figures 1 to 3 , which is a welding method based on groove reconstruction strategy disclosed by the present invention. The welding system 1 is used for groove welding of the process pipeline 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 pipeline 2 is used to be installed on the turntable of the positioner 50, and the turntable can drive the process pipeline 2 to rotate. The welding robot 10 is electrically connected to the controller 30 through the control device 20, and the positioner 50 is electrically connected to the controller 30. The tracking sensor 40 is arranged at the end of the mechanical arm 12 of the welding robot 10 and is fixedly connected to the welding gun 13 on the welding robot 10 to form hand-eye calibration. The tracking sensor 40 is electrically connected to the controller 30.

[0054] Among them, eye-in-hand calibration is used to control the welding process of the welding robot 10.

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

[0056] For example, the controller 30 may be a computer, or a handheld device. In the implementation mode where the controller 30 is a computer, the control functions such as image processing, groove reconstruction (i.e., reconstruction of the initial welding position), welding process planning, and multi-layer and multi-pass welding path point selection are all completed by the computer and the data required by the welding robot 10 is transmitted 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; the welding robot 10 can also perform segmented full-position welding. After each stage of welding is completed, the positioner 50 adjusts the angle of the process pipeline 2 to carry out the next stage of welding.

[0058] The welding method comprises the following steps:

[0059] S101. The groove of the process pipeline 2 is reconstructed through the controller 30. Thus, through the conversion between the weld section and the laser plane feature point, the influence of the coaxiality error, ovality error, groove cutting error and installation error of the process pipeline 2 on the welding quality is better reduced, and the influence of the thermal deformation of the pipeline during the welding process on the welding quality is solved, thereby improving the welding accuracy and weld quality.

[0060] Further, in this embodiment, S101, reconstructing the groove of the process pipeline 2 by the controller 30, includes:

[0061] S1011 , clamp the process pipeline 2 on the turntable of the positioner 50 .

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

[0063] S1012 , the weld image of the process pipeline 2 is displayed in the image of the tracking sensor 40 .

[0064] Among them, the coordinate systems and their conversion relationships involved in the tracking control process of the weld of the process pipeline 2 are as follows: the welding robot 10 involves the base 11 coordinate system {B}, the wrist coordinate system {E} of the manipulator 12 (i.e., the sixth rod coordinate system of the welding robot 10) and the welding gun 13 coordinate system {T}; the tracking sensor 40 is installed at the end of the manipulator 12 and is fixed to the welding gun 13 to form an eye-in-hand hand-eye calibration, and the tracking sensor 40 coordinate system is recorded as {C}; the positioner 50 coordinate system is recorded as {P}, and the Z coordinate system of the positioner 50 coordinate system is definedp The axis is the direction of the rotation axis of the positioner 50.

[0065] In this embodiment, the conversion relationship between the wrist coordinate system and the base 11 coordinate system is expressed as B T E The welding robot 10 can be reset to its origin; the conversion relationship between the welding gun 13 coordinate system and the base coordinate system is recorded as B T T It can be determined by calibrating the welding gun 13 coordinate system; the tracking sensor 40 coordinate system relative to the welding gun 13 remains unchanged and is recorded as T T C The conversion relationship of the laser band on the image in the base coordinate system {B} can be obtained through hand-eye calibration and laser plane calibration; the positioner 50 coordinate system {P} can be calibrated by the three-point method teaching method to obtain its conversion relationship relative to the base 11 B T P .

[0066] Specifically, the welding gun 13 on the welding robot 10 is controlled to approach the weld on the process pipeline 2, so that the weld image is displayed in the image of the tracking sensor 40, and the welding gun 13 on the welding robot 10 is ensured to be located directly above the rotation axis of the positioner 50, and the central axis (i.e., Z T Axis) direction is consistent with the direction of gravity.

[0067] S1013, converting the weld cross-section feature points to the welding gun 13 cross-section feature points to obtain the actual groove feature points of the weld cross-section.

[0068] Continue to refer to Figures 4 to 6 In this embodiment, S1013, converting the weld cross-section feature points to the welding gun 13 cross-section feature points to obtain the actual groove feature points of the weld cross-section, including:

[0069] S10131, extract the coordinates of three feature points P1, P2, P3 on the weld image at each position of process pipeline 2, and convert the coordinates of all feature points into the robot base coordinate system to obtain B P i .

[0070] Specifically, the turntable of the positioner 50 is controlled to rotate uniformly for one circle, and the positions of the characteristic points of the weld image of the process pipeline 2 obtained by image processing on the controller 30 (ie, 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 gun 13 is always kept perpendicular to the ground, and 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 characteristic points on the weld image of a single V-groove is:

[0073] In formula (1), M in The camera intrinsic parameter matrix in the tracking sensor 40 is obtained by calibrating the intrinsic parameters of the tracking sensor 40. C T T is the 4×4 hand-eye calibration inverse matrix obtained through hand-eye calibration, T T B is the transformation matrix of the welding gun 13 relative to the robot base coordinate system obtained by calibrating the welding gun 13; (u i 、v i ) T and (x i ,y i 、z i ) T Represents the pixel coordinates of the three feature points relative to the robot base coordinate system B P1, B P2, B P3.

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

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

[0076] in,

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

[0078] S10132. Calculate the plane Π of each group of groove feature points on process pipeline 2 i .

[0079] Further, in this embodiment, S10132, calculate the plane Π of each group of groove feature points on the process pipeline 2. i ,include:

[0080] S101321, generate the coordinates of each set of feature points in the robot base coordinate system according to the rotation angle of the positioner 50 B P i (j).

[0081] Specifically, since the image coordinates P captured during the image acquisition process iIt is obtained under the premise that the welding gun 13 is not moving, so it is necessary to calculate the three points P1, P2, P3 and the positioner 50 rotation angle θ j Corresponding. Among them, θ j The rotation angle of the process pipeline 2 can be read by the encoder of the positioner 50, and the coordinates of all feature points are converted to the base coordinate system {B}, and the full circle data in the base coordinate system is generated according to the rotation angle of the positioner 50.

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

[0083] In formula (3), Rot( B Z p ,θ j ) is the winding positioner 50Z p Axis rotation angle rotation operator, groove feature points {P1(j), P2(j), P3(j)}, j is the measurement point number, θ j is the turning angle of the positioner 50.

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

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

[0086] S101323, using the Ransac method in the camera coordinate system C P i (j) Points are fitted to form plane Πi.

[0087] Specifically, the Ransac method is used in the camera coordinate system. C P1, C P2 and C The three groups of points in P3 are fitted into three planes, which are 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 the angles β1, β2, and β3 in sequence, includes:

[0093] S101331. Combined with the weld image acquisition, the first group of points is recorded as P 1a , P 2a , P 3a .

[0094] Specifically, the feature points C P i Project them onto the corresponding planes respectively.

[0095] C P Πi = C P i +u i t i , where C P Πi The corresponding plane Π is the obtained series of V-groove contour points on the fitting i The projection on, where i is 1, 2, 3, corresponding to point P i Sequence, u i are the direction vectors of the three planes. i is the parameter of the perpendicular line equation from the point to the plane, t i It can be calculated by the following formula:

[0096]

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

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

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

[0100] Specifically, the rotation axis Z of the positioner 50 is calculated in the camera coordinate system {C} p The intersection points of the axis with the three planes Π1, Π2 and Π3 are denoted as P 1b , P 2b , P 3b .

[0101] S101333, calculate each feature point to the welding gun 13 coordinate system Y T O T Z T Plane distance determination point P 1c , P 2c , P 3c .

[0102] Specifically, calculate C P Πi Each groove contour point and weld feature point in the welding gun 13 coordinate system Y T O T Z T Plane 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, Y of the welding gun 13 coordinate system T O T Z T plane). A T , B T , C T Y T O T Z T The plane normal direction, that is, the X direction of the welding gun 13 coordinate system {T} T Axis direction, D T The origin O of the welding gun 13 coordinate system can be T get.

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

[0106] From the three sets of points, we get three off-plane π T The nearest points are denoted as P 1c , P 2c , P 3c , and record the corresponding point number j.

[0107] S101334, calculate ∠P in sequence 1a P 1b P 1c , ∠P 2a P 2b P 2c , ∠P 3a P 3b P 3c , denoted as β1, β2, β3.

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

[0109] P iw =Rot( C Z P , β i ) ic

[0110] Where: P iw is the actual groove feature point of the weld section, Rot( C Z p , β i ) is the winding positioner 50Z p Axis rotation angle rotation operator, P ic Y coordinate system from feature point to welding gun 13 T O T Z T Plane distance determination point.

[0111] Specifically, according to the calculation formula of the actual groove characteristic points of each weld section:

[0112] P iw =Rot( C Z P , β i ) 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 calculation processes are all calculated in the camera coordinate system.

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

[0116] S102 , planning multi-layer and multi-pass welding through the controller 30 .

[0117] Furthermore, in this embodiment, S102, multi-layer and multi-pass welding is planned through the controller 30, including: determining the rotation speed ω and wire feeding speed wfs of the corresponding process pipeline 2 according to the welding experiment results, and determining the corresponding welding current, weld pass and number of weld layers.

[0118] Specifically, according to the actual shape characteristic point P of the V-groove of each weld section 1w , P 2w and P 3w The height of the weld layer is determined in combination with the welding process. The height of the weld layer can be determined based on the welding process experiment, and the welding process parameters should be kept constant during the subsequent welding of the weld layer and weld pass. Assuming that the expected number of weld layers is Nc, the actual number of weld passes Np is:

[0119]

[0120] Although there are errors in the actual shape of each weld groove, the subsequent cover welding can be planned using the theoretical groove shape. Assuming the theoretical groove angle is α and the groove height is H, the groove cross-sectional area Sv can be obtained by the following formula:

[0121]

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

[0123]

[0124] Therefore, the corresponding pipeline rotation speed ω and wire feeding speed wfs are determined according to the welding test results. S103, the groove of the process pipeline 2 is subjected to a bottom welding.

[0125] Continue to refer to Figures 4 to 7 In this embodiment, S103, the groove of the process pipeline 2 is subjected to the bottom welding, including: the positioner 50 drives the process pipeline 2 to rotate around the Z of the positioner 50. P The axis rotates in the opposite direction, and the control device 20 obtains characteristic points through weld image processing according to the real-time rotation angle of the positioner 50, and uses the β obtained by groove reconstruction i The actual shape characteristic point P of the weld cross section is calculated by iw .

[0126] Specifically, during the base welding stage, the positioner 50 drives the process pipeline 2 to rotate around the Z PThe axis rotates in the opposite direction, and the control device 20 rotates the angle θ in real time according to the positioner 50. The three groups of points P1, P2 and P3 are obtained by processing the weld image. The β obtained by the groove reconstruction is used. i Calculate the actual shape characteristic point P of the V-shaped groove of the weld section 1w , P 2w and P 3w .

[0127] During the root welding, the direction of the V-shaped groove angle bisector is calculated according to the obtained weld characteristic points, and the root welding torch 13 direction Z is determined. T axis.

[0128] Specifically, in order to ensure the welding quality, it is necessary to ensure that the welding gun 13Z T Axis direction in weld plane Π T On the bisector of the groove angle of process pipeline 2. 2w is the origin of the actual weld groove section coordinate system, with the direction vector P 2w P 1w The X-axis direction of the weld groove section coordinate system is the welding gun 13 coordinate system X T The axis direction is the Z axis direction of the weld groove section coordinate system. First, ∠P is calculated based on the three-point coordinates. 1w P 2w P 3w , and then use the rotation formula around the axis to get the welding gun 13 coordinate system Z T Axis direction and transform it to the base coordinate system.

[0129] All welding sections can be planned in advance according to the reconstructed process data, thereby realizing automatic welding of the base weld of the process pipeline 2.

[0130] S104, after the base welding is completed, multi-layer and multi-pass welding is performed on the groove of the process pipeline 2.

[0131] Specifically, in the subsequent weld bead welding except the base welding process, the groove reconstruction is still adopted, the difference is that as the weld bead of the welding layer increases, the number of characteristic points changes accordingly.

[0132] Further, in this embodiment, after S104, the base welding is completed, multi-layer and multi-pass welding is performed on the groove of the process pipeline 2, including:

[0133] S1041, skeletonizing the laser stripes on the weld image, and performing cubic curve fitting on the obtained pixel point coordinates representing the laser stripes using the least square method.

[0134] Specifically, the laser stripes on the weld tracking image are first skeletonized, and then the pixel coordinates representing the laser stripes are obtained for cubic curve fitting using the least square method.

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

[0136] S1042, calculating the average weld height of the corresponding welding layer, and finding the second-order derivative of the cubic curve, searching for the inflection point of the curve and judging whether the inflection point should be retained in combination with the number of welding layers, and then using the retained inflection point as the subsequent weld bead position to plan the multi-layer and multi-pass weld bead position.

[0137] S1043. According to the groove reconstruction, the coordinates of the laser plane multi-layer multi-pass welding path points are converted in the weld section.

[0138] The present application provides a welding method based on a groove reconstruction strategy, a welding system 1 for groove welding of a process pipeline 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 pipeline 2 is installed on a turntable of a positioner 50, the turntable can drive the process pipeline 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 arranged at the end of the mechanical arm 12 of the welding robot 10, and is fixedly connected to the welding gun 13 on the welding robot 10 to form a hand-eye calibration, and the tracking sensor 40 is electrically connected to the controller 30; wherein the welding method includes the following steps: reconstructing the groove of the process pipeline 2 by the controller 30; planning multi-layer and multi-pass welding by the controller 30; and calibrating the groove of the process pipeline 2. Base welding; after the base welding is completed, the groove of the process pipeline 2 is subjected to multi-layer and multi-pass welding; with such an arrangement, on the one hand, compared with the traditional V-shaped groove multi-layer and multi-pass welding, the welding layer and weld planning mostly use ideal geometric figures instead of single-pass weld shapes. When the present application actually controls the welding robot 10 to automatically weld the process pipeline 2, there is no need to unnecessarily simplify the shapes of each weld. It is only necessary to advance the weld cross-sectional contour and more accurately select the welding cross-sectional feature points through the weld contour shape, so as to better select the welding position; on the other hand, through the groove reconstruction, the conversion between the weld cross section and the laser plane feature points can be used to better reduce the influence of the coaxiality error, ellipticity error, groove cutting error and installation error of the process pipeline 2 on the welding quality, and at the same time solve the influence of pipeline thermal deformation on welding quality during welding, thereby improving welding accuracy and weld quality.

[0139] The welding method based on the groove reconstruction strategy provided by the present invention has the following advantages: through the conversion between the weld section and the laser plane feature point, the influence of the coaxiality error, ovality error, groove cutting error and installation error of the process pipeline 2 on the welding quality is better reduced, and the influence of the thermal deformation of the pipeline on the welding quality during the welding process is solved at the same time.

[0140] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0141] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A welding method based on groove reconstruction strategy, characterized in that: The welding system is used for groove welding of process pipelines, and the welding system includes a welding robot, a control device, a controller, a tracking sensor and a positioner. The process pipeline is used to be installed on a turntable of the positioner, and the turntable can drive the process pipeline to rotate. The welding robot is electrically connected to the controller through the control device, and the positioner is electrically connected to the controller. The tracking sensor is arranged at the end of the mechanical arm of the welding robot and is fixedly connected to the welding gun on the welding robot to form hand-eye calibration, and the tracking sensor is electrically connected to the controller. Wherein, 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 means of the controller; Performing base welding on the groove of the process pipeline; After the base welding is completed, multi-layer and multi-pass welding is performed on the groove of the process pipeline.

2. The welding method based on groove reconstruction strategy according to claim 1 is characterized in that: The reconstructing the groove of the process pipeline by the controller includes: Clamping the process pipeline on the turntable of the positioner; The weld image of the process pipeline is displayed in the image of the tracking sensor; The weld section feature points are converted to the welding gun section feature points to obtain the actual groove feature points of the weld section.

3. The welding method based on groove reconstruction strategy according to claim 2 is characterized in that: The step of converting the weld cross-section feature points to the welding gun cross-section feature points to obtain the actual groove feature points of the weld cross-section includes: Extract the coordinates of three feature points P1, P2, and P3 on the weld image at each position of the process pipeline, and convert the coordinates of all feature points into the robot base coordinate system to obtain B P i ; Calculate the plane Π of each group of groove feature points on the process pipeline i ; Calculate angles β1, β2, and β3 in sequence; The calculation formula for the actual groove characteristic points of each weld section is: P iw =Rot( C WITH P ,β i )P ic Where: P iw is the actual groove feature point of the weld section, Rot( C Z p , β i ) is the winding positioner Z p Axis rotation angle rotation operator, P ic Y coordinate system from feature point to welding gun T O T Z T Plane distance determination point.

4. The welding method based on groove reconstruction strategy according to claim 3 is characterized in that: The coordinate transformation relationship of the three feature points on the weld image is: Where: M in The camera intrinsic parameter matrix in the tracking sensor is obtained by calibrating the intrinsic parameters of the tracking sensor. C T T is the 4×4 hand-eye calibration inverse matrix obtained through hand-eye calibration, T T B The welding gun relative to the robot base coordinate system transformation matrix is ​​obtained by welding gun calibration; (u i 、v i ) T and (x i ,y i 、z i ) T Represents the pixel coordinates of the three feature points relative to the robot base coordinate system B P1, B P2, B P3.

5. The welding method based on groove reconstruction strategy according to claim 3 is characterized in that: The calculation of the plane Π where each group of groove feature points on the process pipeline is located i ,include: The coordinates of each set of feature points are generated according to the rotation angle of the positioner in the robot base coordinate system to obtain B P i (j); The coordinates of each set of feature points are converted into the camera coordinate system of the tracking sensor to obtain C P i (j); The Ransac method is used in the camera coordinate system. C P i (j) Point fitting out plane Π i .

6. The welding method based on groove reconstruction strategy according to claim 5 is characterized in that: B P i (j)=Rot( B WITH p ,θ j )P i (j) Among them, Rot( B Z p ,θ j ) is the winding positioner Z p Axis rotation angle rotation operator, groove feature points {P1(j), P2(j), P3(j)}, j is the measurement point number, θ j is the turning angle of the positioner.

7. The welding method based on groove reconstruction strategy according to claim 3 is characterized in that: The sequential calculation of angles β1, β2, and β3 includes: Combined with the weld image acquisition, the first group of points is recorded as P 1a , P 2a , P 3a ; Calculate the distance between the rotation axis of the positioner and each feature point plane Πi, and determine point P 1b , P 2b , P 3b ; Calculate each feature point to the welding gun coordinate system Y T O T Z T Plane distance determination point P 1c , P 2c , P 3c ; Calculate ∠P in sequence 1a P 1b P 1c , ∠P 2a P 2b P 2c , ∠P 3a P 3b P 3c .

8. The welding method based on groove reconstruction strategy according to claim 1, characterized in that: The planning of multi-layer and multi-pass welding by the controller includes: The rotation speed ω and wire feeding speed wfs of the corresponding process pipeline are determined according to the welding test results, and the corresponding welding current, weld bead and number of weld layers are determined.

9. The welding method based on groove reconstruction strategy according to claim 3 is characterized in that: The step of performing base welding on the groove of the process pipeline comprises: The positioner drives the process pipeline to move around the Z direction of the positioner. P The axis rotates in the opposite direction, and the control device obtains characteristic points through weld image processing according to the real-time rotation angle of the positioner, and uses the β obtained by the groove reconstruction i The actual shape characteristic point P of the weld cross section is calculated by iw .

10. The welding method based on groove reconstruction strategy according to claim 1, characterized in that: After the base welding is completed, the groove of the process pipeline is subjected to multi-layer and multi-pass welding, including: The laser stripes on the weld image are skeletonized, and the pixel coordinates representing the laser stripes are obtained to perform cubic curve fitting using the least squares method; Calculate the average weld height of the corresponding weld layer, and find the second-order derivative of the cubic curve, search for the inflection point of the curve and determine whether the inflection point is retained in combination with the number of weld layers, and then use the retained inflection point as the subsequent weld bead position to plan the multi-layer and multi-pass weld bead position; According to the groove reconstruction, the coordinates of the laser plane multi-layer multi-pass welding path points are converted in the weld cross section.

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