Liquid-Cooled Jacket Joining With Tapered Stir Pin Control
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Solution Overview
Problem
The challenge in manufacturing liquid-cooling jackets lies in effectively joining aluminum alloys of varying hardnesses using friction stir welding, which often results in cavity defects and poor joint strength due to uneven material resistance and excessive frictional heat generation.
Innovation Solution
A method involving a tapered stirring pin and specific joining processes is employed, where the stirring pin's diameter reduces towards its tip, and the sealing body's thickness exceeds the step side face height, allowing controlled friction stirring with minimal mixing of harder alloys into softer ones, thus enhancing joining strength.
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 stirring capacities. The larger diameter portion stirs the harder aluminum alloy while the smaller diameter portion stirs the softer alloy, achieving balanced material mixing and eliminating cavity defects
Solution Approach 2:
The stirring pin diameter is changed as a continuous parameter along its length rather than being uniform. This parameter variation allows the pin to adapt to different material hardnesses at different positions, optimizing the stirring effect for each aluminum alloy type and preventing joining defects
2Strength
If the stirring pin is vertically inserted to prescribed depth, then friction stir welding is performed, but excessive frictional heat is generated at starting and ending positions causing metal mixing and poor joint quality
Solution Approach 1:
The stirring pin insertion depth is made dynamic rather than fixed. The pin is gradually inserted to the predetermined depth during the welding process, allowing controlled heat generation and preventing excessive temperature rise at starting and ending positions that would cause metal mixing and poor joints
Solution Approach 2:
The stirring pin is pre-positioned at a starting location before welding begins, and the insertion depth is controlled in advance during the process. This preliminary positioning and controlled insertion prevents excessive frictional heat generation at critical locations, avoiding metal mixing and maintaining joint quality
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 approach ensures balanced material stirring, reduces alloy mixing, and minimizes excessive frictional heat, resulting in improved joint strength and airtightness of the liquid-cooling jacket.
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 track 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 circumferential 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 track, 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 track.