Cooling Unit Weld Structure for Void-Tolerant Joint Reliability
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Solution Overview
Problem
Existing cooling units face challenges in maintaining joining strength and reliability due to voids generated during friction stir welding of aluminum alloy components with differing rigidity, which can lead to stress concentration and crack propagation.
Innovation Solution
A cooling unit design with a void formed in the peripheral wall of the unit main body, positioned away from stress concentration points, and controlled by gap size and tool rotation/movement speed to enhance mechanical strength and prevent crack initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction stir welding is used to join aluminum alloy components with differing rigidity, then joining strength is improved, but voids are generated that lead to stress concentration and reduced reliability
Solution Approach 1:
The patent applies local quality by creating a specific void configuration in the peripheral wall portion rather than attempting to eliminate all voids. The void is strategically positioned and sized (occupying 10-50% of the wall thickness) to maintain joining strength while preventing stress concentration that would compromise reliability. This localized approach accepts voids in non-critical areas while ensuring critical joining regions maintain integrity.
Solution Approach 2:
The patent employs preliminary action by pre-forming the unit main body with a controlled void structure before the friction stir welding process. The void is created during the molding stage, allowing the welding process to proceed without generating harmful voids. This anticipatory design ensures that when welding occurs, the void configuration is already optimized to prevent stress concentration and crack propagation.
2Adaptability or versatility
If aluminum alloy components with differing rigidity are joined, then manufacturing flexibility is improved, but stress concentration occurs leading to crack propagation
Solution Approach 1:
The patent uses local quality by positioning the void specifically in the peripheral wall portion away from stress concentration areas. This localized void configuration allows the use of different aluminum alloy rigidities in various components while preventing crack propagation at critical stress points. The void acts as a stress redistribution feature rather than a defect.
Solution Approach 2:
The patent converts the potential harm of voids (which normally cause stress concentration) into a benefit by strategically positioning and sizing them. The controlled void in the peripheral wall portion serves to redistribute stress away from critical joining regions, actually improving the overall mechanical integrity when joining components with differing rigidity.
3Productivity
If friction stir welding is performed with high tool rotation speed, then welding efficiency is improved, but void formation increases reducing joining quality
Solution Approach 1:
The patent applies preliminary action by pre-forming the void structure during molding before welding. This allows the friction stir welding process to operate at high rotation speeds for improved efficiency without worrying about void formation, since the void configuration is already established and optimized to prevent harmful stress concentration.
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
Secures joining strength and improves reliability by positioning voids away from stress concentration areas, maintaining mechanical integrity and durability even with size and shape variations.
Implementation Method 1
Friction Stir Welding (FSW) is a method for solid-phase welding metal members to each other by moving a rotary tool along a butted portion of metal members while rotating the rotary tool, and by allowing the metal in the butted portion to plastically flow by frictional heat between the rotary tool and the metal members.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3D
AI summary
A cooling unit includes a unit main body including a bottom portion, a peripheral wall portion rising from the peripheral edge of the bottom portion, and a sealing body for sealing an opening of the unit main body. The unit main body is joined to the sealing body through a plasticized region, and a void is formed at a position close to the unit main body with respect to a center of the plasticized region.