Liquid-Cooling Jacket Friction Stir Joining With Flat-Pin Tooling
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Solution Overview
Problem
Conventional methods for manufacturing liquid-cooling jackets using friction stir welding result in large recessed grooves and surface roughness due to the adherence of plastically fluidized material to the tapered surfaces of the rotary tool, leading to reduced joining quality and increased burr formation.
Innovation Solution
A method involving a rotary tool with a base side pin and a tip side pin, where the base side pin has a larger tapered angle and a stair-like step part, and the tip side pin has a flat surface perpendicular to the rotational axis, allowing for controlled friction stirring and reduced adherence of plastically fluidized material, thereby minimizing recessed grooves and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotary tool with a tapered surface is used for friction stir welding, then stable joining can be achieved even when thickness or height position changes, but plastically fluidized material enters the groove causing large recessed grooves, surface roughness, and burrs
Solution Approach 1:
The invention inverts the conventional approach by making the stirring pin surface substantially flat instead of tapered. This reversal prevents plastically fluidized material from entering grooves while maintaining joining stability through the flat surface geometry that controls material flow differently than traditional tapered designs
Solution Approach 2:
The invention applies different surface geometries to different parts of the stirring pin: a substantially flat outer peripheral surface to prevent material adherence and groove formation, while maintaining appropriate pin dimensions and characteristics for effective friction stirring. This local differentiation of surface properties resolves the contradiction between adaptability and precision
2Reliability
If only a stirring pin is used without a shoulder part, then defects are suppressed and load on apparatus is reduced, but plastically fluidized material is not held causing large recessed grooves and expanded parts
Solution Approach 1:
The invention extracts and eliminates the shoulder part from the rotary tool design, using only the stirring pin with a substantially flat outer peripheral surface. This removal of the shoulder component prevents the material trapping issue while the flat surface geometry compensates by controlling material flow to avoid excessive recessed grooves and expanded parts
3Productivity
If a tapered surface with spiral groove is used, then material flow can be controlled, but material adheres to the groove reducing joining quality and increasing burrs
Solution Approach 1:
The invention inverts the conventional grooved tapered surface design by using a substantially flat outer peripheral surface without spiral grooves. This reversal eliminates the material adherence problem while the flat surface still provides effective material flow control through its geometry, maintaining productivity without sacrificing joining 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
The method effectively reduces the size of recessed grooves and surface roughness, enhances joining quality, and improves the strength of the liquid-cooling jacket by ensuring stable friction stirring and proper material flow, while also allowing for deeper insertion of the rotary tool to enhance joining strength.
Implementation Method 1
friction stir welding is performed by rotating a rotary tool provided with a stirring pin and inserting the stirring pin in an overlapped part between metal members
Implementation Method 2
plastically fluidized material can be held to reduce generation of burrs
Implementation Method 3
a primary joining process in which primary joining is performed by friction stirring
Data Source
AI summary
A method for manufacturing a liquid-cooling jacket (1) where heat transfer fluid flows in a hollow part (14) defined by a jacket body (2) and a sealing body (3) includes: an overlapping process in which the sealing body (3) is placed on an end surface (11a) of a peripheral wall part (11) in such a way that the end surface (11a) and a back surface of the sealing body (3) are overlapped each other to form a first overlapped part (H1); and a primary joining process in which primary joining is performed by friction stirring in such a way that a rotary tool (FD) is moved once around a recessed part (13) along the first overlapped part (H1). In the primary joining process, in a state where a base side pin of the rotary tool (FD) is in contact with the sealing body (3), a flat surface of the base (tip) side pin is brought in contact with only the sealing body (3), and a tip of a projection projecting from the flat surface is inserted more deeply than the first overlapped part (H1) to join the first overlapped part (H1).