Liquid-Cooled Jacket Joining for Dissimilar Aluminum Alloys
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Solution Overview
Problem
The conventional method for manufacturing liquid-cooling jackets using friction stir welding faces challenges in joining different aluminum alloys, particularly due to hardness differences between the jacket body and sealing body, leading to cavity defects and poor joint strength, as well as excessive frictional heat generation at starting and ending positions.
Innovation Solution
A method involving a tapered stirring pin and specific butting configurations to minimize mixing of harder alloys and control frictional heat, including forming peripheral wall step portions and adjusting the thickness of the sealing body to ensure balanced joining and reduced metal mixing, with a primary joining process that gradually inserts and withdraws the stirring pin along a set moving track.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction stir welding is performed with a conventional stirring pin on different aluminum alloys, then joining is attempted, but cavity defects occur and joining strength is reduced due to unbalanced material stirring
Solution Approach 1:
The stirring pin is designed with a tapered shape where the diameter varies along its length, creating different local properties. The larger diameter portion contacts the harder jacket body material while the smaller diameter portion contacts the softer sealing body material, enabling balanced material stirring and preventing cavity defects
Solution Approach 2:
The stirring pin geometry is changed from a uniform cylinder to a tapered shape with varying diameter. This parameter change allows the pin to adapt to different material hardnesses at different locations, improving material flow balance and eliminating cavity defects during friction stir welding of dissimilar aluminum alloys
2Strength
If the stirring pin is vertically inserted to a prescribed depth, then friction stir welding is performed, but excessive frictional heat is generated at starting and ending positions causing metal mixing
Solution Approach 1:
The tapered stirring pin creates different contact conditions at different positions along its length. The varying diameter ensures that frictional heat is distributed more uniformly during the welding process, preventing excessive heat concentration at the starting and ending positions that would cause metal mixing
Solution Approach 2:
The stirring pin is gradually inserted into the workpiece during the welding process rather than being instantly inserted to full depth. This preliminary action of gradual insertion allows controlled heat generation and prevents sudden excessive frictional heat at the starting position
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 joins different aluminum alloys with improved strength and reduced metal mixing, preventing cavity defects and excessive frictional heat, resulting in a more reliable and efficient liquid-cooling jacket manufacturing process.
Implementation Method 1
friction stir welding is performed to a butted portion J10 where a side face 102c of a sealing body 102 made of an aluminum alloy is butted against a step side face 101c of a step portion of a jacket body 101 made of an aluminum alloy
Data Source
AI summary
The present invention is characterized by including a primary joining process to perform friction stirring to a first butted portion by moving a stirring pin one round around a sealing body with a predetermined depth along a set moving route set at an inner position relative to an outer peripheral side face in a state that only the stirring pin of a rotary tool being rotated is inserted into the sealing body and that an outer face of the stirring pin is slightly in contact with a step side face of a peripheral wall step portion. In the primary joining process, after only the stirring pin being rotated is inserted into a starting position set at a position on an inner side relative to the set moving route, the stirring pin is gradually inserted to the predetermined depth while an axis of the rotary tool is moved to a position on the set moving route.