# US 12,005,531 B1 · Method of automatically welding welded seam of saddle line for saddle-type T joint > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,005,531 B1 - Document ID: US12005531B1 - Status: Granted - Kind: B1 - Application number: 18/475,243 - Filed: 2023-09-27 - Granted: 2024-06-11 - Earliest claimed: 2023-01-17 - Assignees: Tianjin University - Applicants: Tianjin University - Inventors: Yongdian Han; Zhaowei Xue; Lianyong Xu; Lei Zhao; Kangda Hao - Web page: https://patentgrep.com/patent/US12005531B1 ## CPC - B23K 9/0953: {using computing means} - B23K 9/0216: {Seam profiling, e.g. weaving, multilayer} - B23K 9/028: for curved planar seams - Y02P 90/30: Computing systems specially adapted for manufacturing - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method of automatically welding a welded seam of a saddle line for a saddle-type T joint belonging to the technical field of welding is provided, including: establishing a groove cross-sectional model, solving a variation law of a groove cross-sectional area, and planning a welding bead and a welding process parameter according to the groove cross-sectional area; establishing a welding torch pose mathematical model and obtaining a pose homogeneous transformation matrix T of a welding torch; establishing a three-dimensional model of a main pipe and a branch pipe, building a welding system through offline software, importing welding spot pose information, and generating welding torch pose offline command through the offline software; and performing automatic welding of the welded seam of the saddle line for the saddle-type T joint according to the planned welding bead and the welding process parameter and the generated welding torch pose offline command. ## Claims ### Claim 1 A method of automatically welding a welded seam of a saddle line for a saddle-type T joint, comprising: S1: establishing a groove cross-sectional model, solving a variation law of a groove cross-sectional area, and planning a welding bead and a welding process parameter according to the groove cross-sectional area, wherein the groove cross-sectional area specifically is: S = δ 2 ⁢ tan ⁢ β + δ ⁡ ( n · 1 - ( r m ) 2 - n · 1 - ( r + δ m ) 2 ) 2 - ( ∫ r r + δ n · 1 - ( x 1 m ) 2 ⁢ dx 1 - ∫ r r + δ ( n · 1 - ( r + δ m ) 2 - n · 1 - ( r m ) 2 δ ⁢ ( x 1 - r ) + n · 1 - ( r m ) 2 ) ⁢ dx 1 ) in the equations, δ is a wall thickness, β is an angle between a horizontal direction of a cross section where a welding spot is located and a groove, n is a semi-minor axis of an ellipse, r is a radius of an inner hole of a branch pipe, m is a semi-major axis of the ellipse, and x1 is an abscissa of P 1 = ( x 1 , n ⁢ 1 - ( x 1 m ) 2 ) at any position on a groove cross section; determining whether S max - S mix S mix is greater than a threshold when the welding process parameter is planned, using a changed welding process parameter if yes is determined, using the same welding process parameter if no is determined, and then determining the welding process parameter, wherein Smax is a maximum groove cross-sectional area, Smix is a minimum groove cross-sectional area, the threshold is 0.1 to 0.15, the welding process parameter includes: a protective gas is pure argon, a gas flow rate is 25 L/min to 30 L/min, a dry extension of a welding wire is 12 mm to 15 mm, process parameters of backing welding are: a wire feeding speed 8 m/min to 8.5 m/min, a welding speed 40 cm/min to 45 cm/min, a current 180 A to 195 A, a voltage 15.2 V to 16.3 V, and no swing; process parameters of filling welding are: a wire feeding speed 8 m/min to 9 m/min, a welding speed 30 cm/min to 40 cm/min, a current 180 A to 195 A, a voltage 15.2 V to 16.3 V, a swing amplitude 1 mm to 2 mm, and a frequency 3 HZ to 5 HZ; and process parameters of covering welding are: a wire feeding speed 9 m/min to 10 m/min, a welding speed 30 cm/min to 40 cm/min, a current 195 A to 236 A, a voltage 16.3 V to 17.6 V, a swing amplitude 1.5 mm to 2.5 mm, and a frequency 3 HZ to 5 HZ; S2: establishing a welding torch pose mathematical model, wherein a pose homogeneous transformation matrix T of a welding torch is: T = [ n 1 o 1 a 1 x m n 2 o 2 a 2 y m n 3 o 3 a 3 z m 0 0 0 1 ] , in the equation, ni, where i=1, 2, and 3, is a vector element of a tangent vector {right arrow over (u)} of any point on the saddle line, oi, where i=1, 2, and 3, is a vector element of a Y-axis direction vector {right arrow over (v)} of the welding torch, ai, where i=1, 2, and 3, is a vector element of a Z-axis direction vector {right arrow over (w)} of the welding torch, and xm, ym, and zm are translation distances of the welding spot relative to an origin of a robot, wherein a direction vector of a groove straight line is {right arrow over (l1)}, a tangent vector on a cross section of a main pipe where the welding spot is located is {right arrow over (l2)}, a pose of the welding torch is located at φ 2 , φ is an angle between the groove straight line at any cross section and a tangent line at the welding spot on the main pipe, the Z-axis direction vector of the welding torch is l → 1 ❘ "\[LeftBracketingBar]" l → 1 ❘ "\[RightBracketingBar]" + l → 2 ❘ "\[LeftBracketingBar]" l → 2 ❘ "\[RightBracketingBar]" , an X-axis direction vector of the welding torch is a tangent direction of any point on the saddle line formed by intersection of the main pipe and the branch pipe, and the Y-axis direction vector of the welding torch is determined according to the right-hand rule of the Z-axis direction vector of the welding torch and the X-axis direction vector of the welding torch; S3: establishing a three-dimensional model of the main pipe and the branch pipe, building a welding system through an offline software, and importing a welding spot pose information in a form of (xm, ym, zm, w, p, r), wherein w, p, and r are angles of rotation around an X-axis, a Y-axis, and a Z-axis respectively and are obtained from the pose homogeneous transformation matrix T of the welding torch, and a welding torch pose offline command is generated through the offline software; and S4: performing automatic welding of the welded seam of the saddle line for the saddle-type T joint according to the welding bead and the welding process parameter planned in step S1 and the welding torch pose offline command generated in step S3. ### Claim 2 (depends on 1) The method of automatically welding the welded seam of the saddle line for the saddle-type T joint according to claim 1, further comprising: establishing a coordinate system with an intersection position of a main pipe axis and a branch pipe axis as an origin, a main pipe axis direction as an X-axis direction, a main pipe radial direction as a Y-axis direction, and a branch pipe axis direction as a Z-axis direction, establishing a saddle line welded seam mathematical model under the coordinate system, solving an angle of inclination at any position of the saddle line, and determining whether a segmented welding process planning for upward welding and downward welding is required based on the angle of inclination. ### Claim 3 (depends on 2) The method of automatically welding the welded seam of the saddle line for the saddle-type T joint according to claim 2, wherein a calculation equation of the angle of inclination θ is: { θ = π 2 - cos - 1 ⁢ u → · n → ❘ "\[LeftBracketingBar]" u → ❘ "\[RightBracketingBar]" ⁢ ❘ "\[LeftBracketingBar]" n → ❘ "\[RightBracketingBar]" u → = ❘ "\[LeftBracketingBar]" i j k 2 ⁢ x 0 2 ⁢ y 0 0 0 2 ⁢ y 0 2 ⁢ z 0 ❘ "\[RightBracketingBar]" , in the equation, {right arrow over (u)} is the tangent vector at any position P0(x0, y0, z0) of the saddle line, {right arrow over (n)} is a horizontal plane normal vector (0, 0, 1), and i, j, and k are respectively unit vectors in same directions as the X-axis, the Y-axis, and the Z-axis. ### Claim 4 (depends on 3) The method of automatically welding the welded seam of the saddle line for the saddle-type T joint according to claim 3, wherein the segmented welding process planning for upward welding and downward welding is not required to be performed when the angle of inclination θ does not exceed ±20° at maximum, and the segmented welding process planning for upward welding and downward welding is required to be performed when the angle of inclination θ exceeds ±20° at maximum. ### Claim 5 (depends on 1) The method of automatically welding the welded seam of the saddle line for the saddle-type T joint according to claim 1, wherein in step S4, during multi-layer and multi-bead welding, a value of r in the welding spot pose information is changed, and an offset distance is set and re-imported into the offline software, and the welding torch pose offline command is regenerated.