Step-Shaped Friction Stir Spot Welding Pin for Lower Joining Pressure
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Solution Overview
Problem
Existing friction stir spot welding tools require high joining pressures, especially when joining fiber reinforced thermoplastic resin members, leading to increased equipment size and cost due to the need for robust arms to counteract reaction forces.
Innovation Solution
A friction stir spot welding tool with a pin featuring a step-shaped portion on its tip surface, which facilitates reduced joining pressure by actively scraping and extruding material during the pin preceding process, allowing for a more efficient cutting of continuous fibers and material flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high joining pressure is applied for friction stir spot welding of fiber reinforced thermoplastic resin members, then effective cutting of continuous fibers and welding performance is improved, but equipment size and cost increase due to need for large rigid arms
Solution Approach 1:
The pin tip surface is designed with a specific local structure (step-shaped portion or groove) that concentrates the pressing force locally. This local structural modification enables effective fiber cutting and material stirring with reduced overall pressing force, thereby improving welding performance without requiring large rigid arms
Solution Approach 2:
The invention changes the physical parameter of the pin tip surface by introducing a step-shaped portion or groove structure. This structural parameter change modifies how pressing force is distributed and utilized, enabling reduced joining pressure while maintaining effective fiber cutting capability
2Productivity
If high joining pressure is applied to cut continuous fibers in fiber reinforced thermoplastic resin members, then material stirring and fiber cutting effectiveness is improved, but reaction force increases requiring larger equipment
Solution Approach 1:
The step-shaped portion or groove on the pin tip surface creates localized high-stress regions that efficiently cut fibers and stir material. This local quality enhancement allows effective material processing with reduced overall pressing force, thereby reducing reaction force on the equipment
Solution Approach 2:
The pin tip surface is segmented into different levels or zones through the step-shaped portion or groove structure. This segmentation creates distinct functional zones that improve material stirring efficiency and reduce the force required for effective fiber cutting
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 step-shaped tip surface reduces the required pressing force, enabling the tool to be mounted on smaller robots or devices, thereby minimizing equipment size and cost while maintaining effective welding performance.
Implementation Method 1
friction stir spot welding
Implementation Method 2
press-fitting the pin into a joining object
Data Source
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AI summary
A friction stir spot welding tool includes: a cylindrical pin that rotates about an axis; a shoulder having a hollow portion into which the pin is inserted; and a driving unit that performs driving of press-fitting the pin into a joining object while rotating the pin and driving of retracting the shoulder with respect to the joining object. A step-shaped portion forming a step in a rotation direction of the pin is provided on at least a part of a tip surface of the pin.