CMT Overlaying of Bimetallic Pipe Openings With Saddle-Line Path Planning
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Solution Overview
Problem
Existing welding technologies, such as manual arc welding, are inefficient and unreliable for overlaying complex intersecting curves on the side walls of composite pipes used in oil and gas pipelines, leading to quality and safety issues due to exposure of carbon steel at openings.
Innovation Solution
A CMT automatic overlaying method is developed, which involves establishing a mathematical model of the pipe's opening, determining the saddle line trajectory, dividing it into welding runs, and planning an offline overlaying sequence using a simulation model to achieve precise and efficient robot welding, reducing heat input and dilution rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual arc welding is used for overlaying on complex saddle-shaped curves, then flexibility and adaptability are maintained, but welding efficiency and quality consistency deteriorate
Solution Approach 1:
The patent replaces manual mechanical welding operations with an automated robot welding system. The robot executes pre-calculated trajectories to automatically perform overlaying on complex saddle-shaped curves, eliminating manual intervention while maintaining precision and consistency. This substitution dramatically improves welding efficiency and quality consistency.
Solution Approach 2:
The patent performs preliminary mathematical modeling and trajectory calculation before actual welding. The complex saddle-shaped surface is modeled mathematically, and the optimal welding path is pre-calculated and stored. During welding, the robot simply follows this pre-planned trajectory, enabling high-speed automated operation without real-time complex calculations.
2Productivity
If robot welding is implemented for automated overlaying, then welding efficiency and consistency improve, but system complexity and programming difficulty increase
Solution Approach 1:
The patent creates a mathematical copy or digital model of the complex saddle-shaped physical surface. This virtual model allows the system to calculate and store welding trajectories without requiring complex real-time control programming. The robot simply follows coordinates derived from this mathematical copy, significantly reducing programming complexity.
Solution Approach 2:
The patent divides the complex welding task into segmented steps: mathematical modeling of the surface, trajectory calculation based on the model, and execution of pre-calculated paths. This segmentation separates the complex computational work from the welding execution, making the overall system more manageable and easier to program.
3Reliability
If conventional welding methods are used on opened pipe sections, then carbon steel exposure is prevented, but heat input increases causing distortion and dilution
Solution Approach 1:
The patent changes the welding process parameters by adopting CMT (Cold Metal Transfer) technology instead of conventional arc welding. CMT operates at lower temperatures and currents, significantly reducing heat input to the pipe material. This prevents thermal distortion and minimizes dilution of the nickel-based overlay, while still achieving complete coverage to prevent carbon steel exposure and maintain corrosion resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method stabilizes the welding process, improves efficiency, and enhances the quality and accuracy of weld overlays, reducing susceptibility to external interference and achieving excellent corrosion resistance and intergranular corrosion test results.
Implementation Method 1
cold metal transfer (CMT) welding has been widely used in the field of overlaying due to its advantages of small heat input, low dilution rate, and no spatter
Data Source
AI summary
The invention belongs to the field of welding technology and discloses a CMT automatic overlaying method for opening in side wall of bimetallic composite pipes. The method includes: establishing a mathematical model of the opening in a side wall to be welded; Based on the mathematical model, determining the trajectory of the saddle line during overlaying; dividing the trajectory of the saddle line into several welding runs, all of which adopt the downslope welding process; establishing a three-dimensional model of the opening in the side wall to be welded and a CMT overlaying system simulation model; Based on the simulation model, planning the overlaying path of the CMT overlaying, and generating an overlaying offline instruction; Based on the offline instruction, performing CMT overlaying on the opening in the side wall to be welded according to the overlaying sequence, so as to obtain a weld overlay.