Friction Stir Joining Rotary Tool for Liquid-Cooled Jacket Groove Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing liquid-cooled jackets using friction stir joining result in increased concave groove size and surface roughness, along with bulging portions due to inadequate material pressing and adherence issues during the joining process.
Innovation Solution
A method involving a rotary tool with a base-end-side pin and a tip-end-side pin of varying taper angles, forming a stairs-like pin step portion, which reduces the concave groove size and surface roughness by effectively pressing and guiding the plastically fluidized material, and includes a provisional joining step to stabilize the abutted portions before main joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction stir joining is performed with only the stir pin contacting the metal members (as in Patent Document 1), then the occurrence of defects is prevented and load is reduced, but the concave groove widens and the joined surface increases in roughness
Solution Approach 1:
The rotary tool is segmented into two distinct pins: a stir pin with a spiral groove for material mixing and a pressing pin with a tapered surface for material compression. This segmentation allows each pin to perform its specialized function independently, preventing defects while maintaining surface quality
Solution Approach 2:
The invention merges the functions of material fluidization (stir pin) and material pressing (pressing pin) into a single rotary tool assembly. The pressing pin works in conjunction with the stir pin to simultaneously achieve defect prevention and surface quality improvement
2Object-generated harmful factors
If the shoulder portion is pushed onto the metal member to press plastically fluidized material, then burr generation is prevented, but the concave groove increases in size when height position changes
Solution Approach 1:
The pressing pin features a localized tapered pressing surface at its tip, concentrating the pressing action precisely where needed. This localized pressing prevents burr generation while minimizing the concave groove size, unlike the broad shoulder portion that causes excessive groove formation when height varies
3Reliability
If tapered surfaces are formed on the shoulder portion and stir pin (as in Patent Document 2), then stable joining is achieved, but the plastically fluidized material intrudes into the groove causing friction and deteriorating joining quality
Solution Approach 1:
Instead of forming tapered surfaces on the stir pin that create grooves for material to enter, the invention inverts the approach by using a separate pressing pin with a tapered pressing surface. This prevents material intrusion into the stir pin groove, eliminating friction between adhered material and base metal while maintaining joining stability
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 reduces the size of the concave groove and bulging portions, enhances joining quality by minimizing material adherence and surface roughness, and stabilizes the joining process, even when the thickness or height of the metal members changes.
Implementation Method 1
a rotary tool used for friction stir joining, including a shoulder portion and a stir pin suspended from the shoulder portion
Implementation Method 2
the plastically fluidized material can be pressed to prevent the generation of burrs
Data Source
AI summary
Provided is a method for manufacturing a liquid-cooled jacket, to reduce the size of a recessed groove on a surface of a metal member and also to reduce roughness of an abutted surface. The method includes: a placing step of placing a jacket body and a sealing body, a first main joining step of performing friction stirring by moving a main joining rotary tool around along a first abutted portion, and a second main joining step of performing friction stirring by moving the main joining rotary tool around along a second abutted portion. The main joining rotary tool has a base-end-side pin and a tip-end-side pin. A taper angle of the base-end-side pin is grater than a taper angle of the tip-end-side pin and a stairs-like pin step portion is formed on an outer circumferential surface of the tip-end-side pin.