Laminated Core Block Welding With Low-Heat Crack Control
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Solution Overview
Problem
Conventional welding methods often result in cracks and deformation when applied to laminated devices with braze boundaries, particularly in microchannel apparatus, leading to leaks and mechanical weakness.
Innovation Solution
A method involving a reciprocating welding technique with intermittent arc discharge and low heat input, using a welding composition that minimizes diffusion into the core block, and employing CMT or fiber laser welding to attach enclosures to brazed laminated structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional welding is used on laminated apparatus with braze boundaries, then welding can be performed to join components, but cracks form between the sheets and the apparatus is deformed or weakened
Solution Approach 1:
The patent applies Cold Metal Transfer (CMT) welding which fundamentally changes the welding parameters - operating at significantly lower temperatures and with controlled metal transfer - to prevent the thermal damage and cracking that occurs with conventional welding on brazed laminated structures
Solution Approach 2:
The patent uses a multi-material approach combining different welding compositions with specific properties - including low-alloy steel wires with controlled carbon and alloy content - to achieve welds that are compatible with the braze boundaries and prevent cracking while maintaining structural integrity
2Strength
If conventional welding is used on laminated apparatus, then joining can be achieved, but the apparatus becomes deformed or weakened
Solution Approach 1:
CMT welding changes the thermal parameters by operating at lower temperatures and shorter durations, preventing the heat-affected zone expansion and thermal distortion that characterize conventional welding, thus maintaining the original shape and dimensional stability of the laminated apparatus
3Strength
If welding composition is applied to the core block, then adhesion is achieved, but diffusion of welding composition into the core block occurs
Solution Approach 1:
The controlled, low-temperature CMT welding process limits the diffusion of welding composition into the core block by maintaining temperatures below the threshold for excessive diffusion, while still achieving adequate adhesion through proper weld parameter control and composition selection
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
Reduces cracks and leaks by maintaining the integrity of laminated apparatus, allowing for efficient access and maintenance of microchannels without damaging the core block, and enabling precise welding along or across brazing layers.
Implementation Method 1
applying a metal onto the laminated apparatus by a welding technique wherein a wire moves in a reciprocating motion (moving alternatively back and forth) and wherein a spark is generated when the wire touches and/or is pulling away from the laminated apparatus
Implementation Method 2
a welding composition disposed on the core block and adhering to the braze composition; wherein the welding composition is diffused 2 mm or less into the core block
Data Source
AI summary
The invention describes methods of welding onto laminated devices using a low temperature welding process. Also described are laminated devices with welds that do not disrupt a brazed core block of sheets in the laminated devices. Novel laminated devices with welded features for servicing the devices are also described.