Fuel Cell Bipolar Plate Welding Without End-Weld Perforation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing bipolar plate welding methods in fuel cells often result in perforation at the end of the weld due to energy concentration, leading to leaks between fluid channels, and existing solutions like gradually increasing and decreasing laser power are not effective for short-range welds, resulting in incomplete fusion and insufficient weld strength.
Innovation Solution
A laser welding method where the laser emitter is turned off before reaching the end point of the predetermined trajectory, allowing the alignment point to continue moving along the trajectory, ensuring the bipolar plates are securely connected without perforations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is used to weld bipolar plates, then welding efficiency is improved, but perforation occurs at the end of the weld due to energy concentration
Solution Approach 1:
The method applies preliminary action by extending the laser irradiation beyond the nominal weld endpoint to a predetermined endpoint. This anticipates the thermal diffusion effect where heat continues to conduct into the material after the laser passes, ensuring complete fusion at the endpoint without causing perforation. The alignment point moves along a trajectory that includes this extended irradiation zone.
Solution Approach 2:
The method changes the parameter of laser irradiation endpoint from the nominal weld endpoint to a predetermined endpoint that accounts for thermal diffusion. This parameter adjustment ensures that the laser energy is applied sufficiently beyond the visible weld end to achieve complete fusion, while the system controls the total energy input to prevent perforation.
2Reliability
If laser power is gradually increased and decreased during welding, then perforation is avoided, but incomplete fusion occurs in short-range welds
Solution Approach 1:
The method applies preliminary action by pre-determining the endpoint of laser irradiation to extend beyond the nominal weld endpoint. This ensures sufficient heat accumulation and thermal diffusion at the endpoint to achieve complete fusion, particularly for short-range welds where the gradual power adjustment method fails to provide adequate energy input.
3Manufacturing precision
If laser irradiation extends beyond the weld endpoint, then complete fusion is achieved, but energy waste increases
Solution Approach 1:
The method applies preliminary action by pre-calculating and pre-determining the exact endpoint where laser irradiation should terminate, based on the relationship between laser speed, power, and material thickness. This predetermined endpoint optimizes the balance between achieving complete fusion and minimizing energy waste, avoiding both insufficient fusion and excessive energy consumption.
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 prevents perforations and ensures uniform weld depth, maintaining the integrity of the bipolar plate connections and preventing leaks, while enhancing welding efficiency.
Implementation Method 1
activating a laser emitter of the laser welding device
Implementation Method 2
laser welding is generally employed
Data Source
AI summary
A laser welding method, a fuel cell, and a computer readable medium are disclosed. The laser welding method includes (i) securing the bipolar plate in place and fitting an area to be welded of the bipolar plate, (ii) determining a predetermined trajectory on the area to be welded for an alignment point of a laser welding device, the predetermined trajectory including a starting point and an end point, (iii) moving the alignment point of the laser welding device along the predetermined trajectory from the starting point and activating a laser emitter of the laser welding device, and (iv) turning off the laser emitter prior to the end point of the predetermined trajectory and keeping the alignment point moving along the predetermined trajectory until the end point of the predetermined trajectory is reached. The method and the device according to this disclosure effectively avoid a perforation defect in bipolar plate welding.