Concentric Cylinder Welding Energy Control for Residual Stress
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Solution Overview
Problem
Welding of cylindrical member pairs in high-temperature corrosive environments often results in uneven cooling and residual stress, leading to potential stress corrosion cracking, particularly in components like injectors exposed to acidic condensed water.
Innovation Solution
A welding method involving a rotation welding step and an energy adjustment step, where energy is applied from multiple locations around the axis to ensure a relationship of Pd+Pw>θ, with Pd being the output decrease rotation angle, Pw the overlap rotation angle, and θ the separation angle, to equalize temperature distribution and reduce residual stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If energy is applied from multiple locations around the axis during rotation welding, then uniform temperature distribution is achieved and residual stress is reduced, but the device complexity and control difficulty increase due to the need to coordinate multiple applying units with rotation
Solution Approach 1:
The welding energy application is segmented into multiple discrete applying units positioned at different locations around the axis. Each applying unit independently applies energy to a specific circumferential position, allowing the system to achieve uniform temperature distribution by coordinating multiple segmented energy sources rather than using a single complex energy application mechanism
Solution Approach 2:
The applying units operate in a periodic sequence coordinated with the rotation of the cylindrical member pair. By synchronizing the energy application timing with the rotational position, the system maintains uniform temperature distribution while managing the complexity of multiple applying units through rhythmic, predictable operation cycles
2Strength
If the output of applying units is adjusted during the welding process, then residual stress and deformation are reduced, but the control precision requirements increase to maintain the relationship Pd+Pw>θ
Solution Approach 1:
The output adjustment parameters (Pd, Pw, and θ relationships) are predetermined and programmed into the control system before welding begins. By pre-calculating the required energy adjustments based on the geometric relationships between applying units, the system reduces residual stress while avoiding the need for complex real-time precision control during the welding process
Solution Approach 2:
The control system monitors the welding process and adjusts the output of applying units based on feedback from sensors that detect temperature distribution and welding progress. This feedback mechanism allows the system to maintain the Pd+Pw>θ relationship and reduce residual stress while compensating for variations in material properties and welding conditions
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 effectively reduces residual stress and prevents deformation by ensuring uniform energy application and cooling across the welded cylindrical member pair, thereby minimizing the risk of stress corrosion cracking.
Implementation Method 1
applying units for applying energy to a welding portion of the cylindrical member pair
Data Source
AI summary
An adjustment of the amount of energy in at least one specific applying unit is executed when energy is applied to a cylindrical member pair in which another cylindrical member is inserted inside a cylindrical member to melt and weld the cylindrical member pair in a circumferential direction. The adjustment is executed in association with a rotation angle to satisfy a relationship of Pd+Pw>θ, wherein Pd is an output decease rotation angle that decreases the energy amount from a steady energy amount HP applied from the specific applying unit in a welding end process, Pw is an overlap rotation angle at which the irradiation parts around the cylindrical member pair overlap with the steady energy amount HP, and θ is a separation angle between the specific applying unit and another applying unit adjacent to each other in a rotation direction around the axis.