CLADDING TECHNOLOGY SHANXI CO., LTDPro/E-Based Simulation Analysis of Overlay Welding Motion on Intersecting Curved Surfaces
Literature Overview
This 2011 publication by Wang Xinhui, Yu Dan, Yang Kefei, and Meng Zhaolin from the Harbin Welding Research Institute (Institute of Welding, China Academy of Machinery Science and Technology) addresses the application of Pro/Engineer (Pro/E) CAD software for the simulation and analysis of overlay welding motion trajectories on intersecting curved surfaces. The research was supported by the Institute of Welding Technology Development Fund (Grant No. 200910126). This work represents an important advancement in the digitalization of welding process planning, particularly for complex geometries encountered in pressure vessel fabrication, heat exchanger manufacturing, and other heavy industrial applications where overlay welding is performed on surfaces with intersecting curvatures.
Core Technical Content
The Challenge of Overlay Welding on Complex Geometries
Overlay welding on intersecting curved surfaces presents several unique challenges that distinguish it from overlay welding on flat or simple curved surfaces:
- Variable weld bead geometry: The intersection of two curved surfaces creates regions where the weld bead cross-section varies continuously, affecting heat input distribution, solidification rate, and microstructural development.
- Tool path planning complexity: The welding torch or wire must follow a trajectory that maintains consistent standoff distance, travel angle, and deposition rate across the entire curved surface, which requires sophisticated kinematic analysis.
- Thermal distortion prediction: The asymmetric heat input on curved surfaces can cause significant thermal distortion of the workpiece, particularly in thin-walled components or components with large area-to-thickness ratios.
- Process parameter adaptation: Welding parameters such as current, voltage, travel speed, and wire feed speed may need to be dynamically adjusted along the weld path to maintain consistent overlay quality.
Pro/E-Based Simulation Methodology
The simulation approach described in this publication employs Pro/E (now known as Creo Parametric) CAD software to model the workpiece geometry, define the overlay weld path, and analyze the kinematic requirements of the welding process. The methodology involves several key steps:
Step 1: Geometric modeling
The workpiece geometry is modeled in Pro/E with precise definition of the intersecting curved surfaces. The model includes all relevant geometric features, including surface curvatures, intersection lines, and dimensional tolerances that affect the overlay welding process.
Step 2: Weld path generation
The overlay weld path is generated on the surface of the model, taking into account the required overlay thickness, weld bead width, and overlap between adjacent passes. The path generation algorithm must account for the variable surface curvature and ensure that the weld beads are spaced to achieve uniform coverage of the surface.
Step 3: Kinematic analysis
The welding torch or wire trajectory is analyzed to determine the required motion of the welding system (robotic or manual) to follow the defined path. This includes analysis of the torch angle, standoff distance, and travel speed requirements at each point along the path.
Step 4: Thermal and mechanical analysis
The simulation can be extended to include thermal analysis (using finite element methods) to predict temperature distributions, cooling rates, and residual stress development in the overlay and base material. This information is critical for predicting potential defects such as cracking, porosity, and distortion.
Key Simulation Results and Process Insights
| Analysis Parameter | Finding | Engineering Implication |
|---|---|---|
| Torch angle variation | 5–15° variation required along intersecting curve | Torch must be dynamically reoriented to maintain consistent weld geometry |
| Travel speed variation | 10–30% variation along path | Speed must be adjusted to maintain consistent heat input per unit length |
| Standoff distance | Must be maintained within ±1 mm | Critical for arc stability and deposition efficiency |
| Thermal distortion | Maximum 0.5–2.0 mm displacement predicted | Fixturing and clamping strategy must account for predicted distortion |
| Dilution variation | 5–20% variation along path | Multi-pass strategy must compensate for variable dilution |
Integration with Robotic Welding Systems
The simulation results can be directly integrated with robotic welding systems to generate the motion programs required for automated overlay welding. The Pro/E model and weld path data can be exported to the robot controller in a format compatible with the robot's programming language. This integration enables:
- Precise trajectory control of the welding torch along the complex curved surface
- Dynamic adjustment of welding parameters based on the position along the weld path
- Real-time monitoring and feedback control of the welding process
- Repeatable and consistent overlay quality across multiple production units
Engineering Practice Applications
The simulation methodology described in this publication has been applied to several practical engineering problems:
- Heat exchanger tube sheet overlay: The intersection of the tube sheet face and the tube holes creates a complex curved surface that requires overlay welding for corrosion resistance. The simulation enables precise planning of the overlay weld path to ensure complete coverage of the tube sheet face while avoiding interference with the tube holes.
- Pressure vessel head overlay: The dished or ellipsoidal heads of pressure vessels have intersecting curvatures that complicate the overlay welding process. The simulation enables optimization of the weld path to minimize the number of passes and maximize overlay efficiency.
- Nuclear reactor vessel internal overlay: The internal surfaces of nuclear reactor vessels often have complex geometries that require overlay welding for corrosion resistance. The simulation provides a means to plan and optimize the overlay process before committing to the actual welding operation, which is critical given the stringent quality requirements and limited access to the vessel interior.
Key Reflections and Implications
This work represents an important step in the digitalization of welding process planning, demonstrating how CAD-based simulation can be applied to solve practical problems in overlay welding on complex geometries. The integration of geometric modeling, kinematic analysis, and thermal/mechanical simulation provides a comprehensive tool for optimizing the overlay welding process before actual welding begins. This approach reduces the risk of process defects, minimizes the need for rework, and improves overall manufacturing efficiency. For modern welding practitioners, this work highlights the value of digital simulation in welding process development, and the principles described can be extended to more advanced simulation environments that include real-time process monitoring and adaptive control. The use of Pro/E as the simulation platform also demonstrates that commercially available CAD software can be effectively applied to welding process analysis, without requiring specialized or proprietary simulation tools.