Liquid-Cooled Jacket Welding for Dissimilar Aluminum Alloys
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Solution Overview
Problem
The challenge in manufacturing liquid-cooled jackets lies in joining aluminum alloys of different material types, where the higher hardness of the jacket main body relative to the seal body results in uneven material resistance during friction stir welding, leading to void defects and compromised joining strength.
Innovation Solution
A method involving a rotary tool with a tapered stirring pin that primarily contacts the seal body, forming inclined surfaces on the jacket main body and seal body to facilitate friction stir welding, reducing the mixing of harder alloys and preventing void defects by ensuring balanced material resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If friction stir welding is performed with the stirring pin contacting both the jacket main body and seal body, then the joining process can be completed, but material resistance becomes uneven and void defects occur
Solution Approach 1:
The joining process is divided into two distinct stages: a preliminary joining step where the stirring pin contacts both the jacket main body and seal body to initiate the welding process, and a main joining step where the stirring pin contacts only the seal body to complete the welding. This segmentation allows optimization of each stage's parameters independently, preventing material resistance imbalance and void defects while maintaining high joining efficiency.
Solution Approach 2:
The preliminary joining step is performed before the main joining step to prepare the interface between the jacket main body and seal body. By conducting this preliminary action where the stirring pin contacts both components, the material resistance is initially balanced, and then in the main joining step, the stirring pin contacts only the seal body to complete the welding without causing void defects.
2Strength
If the stirring pin contacts the harder jacket main body during friction stir welding, then the joining process can proceed, but the material resistance becomes too high causing uneven stirring and void defects
Solution Approach 1:
The preliminary joining step performs the initial welding action where the stirring pin contacts both the harder jacket main body and the softer seal body. This preliminary action prepares the interface and reduces material resistance imbalance. Subsequently, in the main joining step, the stirring pin contacts only the seal body, ensuring uniform plastic flow and preventing void defects while maintaining high joining strength.
Solution Approach 2:
The joining process parameters are changed between two stages: in the preliminary joining step, the stirring pin contacts both components with specific rotational speed and feed rate to initiate welding; in the main joining step, the parameters are adjusted so the stirring pin contacts only the seal body, optimizing plastic flow uniformity and preventing void defects while maintaining joining strength.
3Ease of manufacture
If conventional friction stir welding is used on butt portions, then the joining can be performed, but void defects occur in the plasticized region due to uneven material resistance
Solution Approach 1:
The conventional single-step friction stir welding process is segmented into two distinct steps: a preliminary joining step and a main joining step. This segmentation transforms the simple but unreliable conventional process into a more complex yet reliable two-stage process that prevents void defects by controlling material resistance distribution, thereby improving joining reliability while maintaining ease of manufacture.
Solution Approach 2:
The preliminary joining step is introduced as a preparatory action before the main joining step. This preliminary action ensures proper material flow and reduces void formation by initially contacting both the jacket main body and seal body, then transitioning to contacting only the seal body in the main joining step, thereby improving joining reliability without significantly complicating the manufacturing process.
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 aluminum alloys of different types without deteriorating the joining strength, ensuring a well-balanced plastic flow and reducing the occurrence of void defects, thus enhancing the structural integrity of the liquid-cooled jacket.
Implementation Method 1
friction stir welding is performed on a butt portion J10 formed by butting a step side surface 101c provided in a step part of a jacket main body 101 made of an aluminum alloy and a side surface 102c of a seal body 102 made of an aluminum alloy
Implementation Method 2
when friction stir welding is performed as shown in FIG. 24, material resistance received by the stirring pin from the jacket main body 101 side is large compared with material resistance received by the stirring pin from the seal body 102
Data Source
AI summary
A jacket main body is formed of a first aluminum alloy. A seal body is formed of a second aluminum alloy. The first aluminum alloy is higher in hardness than the second aluminum alloy in material type. A method includes: a preparing step of forming on an peripheral wall part a step part having a step bottom surface and a step side surface obliquely rising; a mounting step of mounting the seal body on the jacket main body to form a first butt portion and putting the step bottom surface and a back surface of the seal body on each other to form a second butt portion; a main joining step of performing friction stir welding while only the stirring pin of the rotary tool rotating contacts with only the seal body.