Consumable Friction Bit Joining Tool for Flush Surface Joints
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Solution Overview
Problem
Conventional friction stir processing (FSP) methods often leave voids and require additional finishing steps due to the retraction of non-consumable bits, whereas friction bit joining (FBJ) with consumable bits aims to produce a near-finished surface without flash or debris, but existing FBJ tools may not achieve a flush surface without subsequent processing.
Innovation Solution
A FBJ tool with a tapered bit and driver system that allows the bit to remain in the workpiece, featuring a non-cutting tip for displacement rather than cutting, and includes mechanical interlocking features for torque transmission and axial movement, enabling the bit to be consumed within the joint while maintaining a flush surface without additional finishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional FSP uses a non-consumable bit, then the tool can be reused for multiple operations, but a void is left when the tool is retracted and additional finishing steps are required
Solution Approach 1:
The patent employs a consumable bit that is intentionally designed to be consumed during the friction bit joining process. The bit is made of a material that is softer than the workpiece material, allowing it to be gradually consumed and mixed into the workpiece during stirring. This consumption eliminates the void problem and produces a flush surface without requiring additional finishing steps, directly resolving the contradiction between tool reusability and surface finish quality.
2Manufacturing precision
If FBJ uses a consumable bit to eliminate voids, then a near-finished surface is produced, but the bit must be precisely controlled to remain flush with the workpiece surface
Solution Approach 1:
The tool is segmented into two distinct components: a consumable bit and a driver. The bit contains recessed interlocking features that engage with protruding interlocking features on the driver. This segmentation allows the driver to transmit torque and control the bit's rotation and axial movement independently, enabling precise control of the bit's position relative to the workpiece surface while simplifying the overall control mechanism.
Solution Approach 2:
The mechanical interlocking features serve as an intermediary mechanism between the driver and the bit. These interlocking features transmit torque from the driver to the bit and control the bit's axial movement, allowing precise control of the bit's position and orientation during the joining process without requiring complex control systems.
3Productivity
If the bit is rotated at high speed for efficient joining, then productivity increases, but control of the bit's axial movement and positioning becomes more difficult
Solution Approach 1:
The patent employs dynamic control of the bit through the interlocking features between the driver and bit. The interlocking features allow the driver to dynamically control the bit's rotation speed and axial movement during the joining process. This dynamic control system enables high-speed rotation for productivity while maintaining ease of operation through automatic positioning control, resolving the contradiction between joining speed and positioning control.
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 FBJ tool enhances weld strength and efficiency by increasing material flow and translational speed, producing a stronger bond and eliminating the need for post-processing, as the bit remains flush with the workpiece surface upon completion, ensuring a refined grain structure and improved mechanical properties.
Implementation Method 1
FSP uses the motion of a pin pressed against the surface of a weldable material to generate heat and friction to move the weldable material
Implementation Method 2
The material can plasticize and physically stir together with a second material to which the first material is joined
Data Source
AI summary
A tool for friction bit joining a workpiece material includes a bit with a tapered pin and a non-cutting tip. The bit has a top surface opposite the pin with at least one feature recessed in, or extending from, the top surface and configured to transmit torque to the bit to rotate the bit around a rotational axis.