Bipolar Plate Strand Joining with Local Heating and Rolling Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Laser-welded bipolar plates in fuel cells face risks of pore formation and media leaks, particularly at longer weld seams, and require complex clamping technology for precise welding.
Innovation Solution
A method involving preformed unipolar plate strands with webs and channels, heated to a joining temperature using a laser or induction heating, and joined under pressure in a rolling gap to form a bipolar plate strand, eliminating the need for additional clamping technology and optimizing channel and web geometries for improved flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is used to join unipolar plates, then welding automation and productivity are improved, but pore formation and media leaks occur particularly at longer weld seams
Solution Approach 1:
The continuous weld seam is divided into multiple discrete spot welds arranged in a matrix pattern. Instead of creating one long continuous seam that is prone to leaks, the joining process creates multiple localized fusion points that are distributed across the interface between unipolar plates, thereby eliminating the continuous leak path while maintaining automated welding
Solution Approach 2:
The welding process applies heat and pressure locally at specific matrix positions rather than along a continuous line. Each spot weld creates a localized fusion zone with optimal sealing properties, and the spacing between spots allows for proper heat dissipation and material flow, preventing pore formation while maintaining automated precision
2Manufacturing precision
If laser welding is used to join unipolar plates, then welding precision is improved, but complex clamping technology is required to position plates precisely
Solution Approach 1:
The unipolar plates themselves provide the positioning function through their geometric features. The plates are designed with specific dimensions and tolerances that allow them to self-align during the stacking and welding process, eliminating the need for external clamping devices. The manufacturing precision is achieved through controlled spot weld placement rather than through complex mechanical positioning systems
3Ease of operation
If additional embossing is provided on channels and webs to accommodate clamping means, then clamping capability is improved, but bipolar plate design complexity and manufacturing steps increase
Solution Approach 1:
The clamping function is extracted from the bipolar plate design itself. Instead of adding embossing features to the plates to accommodate clamping means, the solution removes the need for clamping devices entirely by using a spot weld matrix process that does not require external positioning or clamping equipment. This simplifies both the plate design and the overall manufacturing system
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 reduces the risk of leaks and production scrap, simplifies the welding process, and allows for optimized bipolar plate design, ensuring reliable sealing and electrical contacting.
Implementation Method 1
local heating of at least one surface area of a surface of one or both of the unipolar plate strands, the surface area immediately before or upon entry of the unipolar plate strands into the rolling gap being heated to a joining temperature
Implementation Method 2
joining the unipolar plate strands at the at least one surface area to form a bipolar plate strand during transport of the unipolar plate strands through the rolling gap under the action of pressure
Data Source
AI summary
A method for producing a bipolar plate strand comprises: providing a first and a second unipolar plate strand, the unipolar plate strands comprising a plurality of webs and a plurality of channels extending between two adjacent webs in each case, guiding the unipolar plate strands towards a rolling gap of a pair of rollers of a rolling device provided with rolling structures, local heating of one surface area of a surface of at least one of the unipolar plate strands, the surface area immediately before or upon entry of the unipolar plate strands into the rolling gap being heated to a joining temperature, and joining the unipolar plate strands at the at least one surface area to form a bipolar plate strand during transport of the unipolar plate strands through the rolling gap under the action of pressure.