Coaxial Refill Friction Stir Spot Welding for Accurate Positioning
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Solution Overview
Problem
Current friction stir spot welding technologies face issues with accuracy due to bending moments from side-shaft drives and hysteresis problems from passive displacement adjustments, leading to inaccuracies in welding position and quality.
Innovation Solution
A refill friction stir spot welding device with a coaxial drive system that synchronizes the movement of a stir pin and stir sleeve using an axial drive assembly and rotary drive assembly, ensuring precise control over displacement and pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If side-shaft drive is used for displacement adjustment, then displacement control is achieved, but bending moment is generated causing loss of welding position accuracy
Solution Approach 1:
The patent inverts the conventional side-shaft drive arrangement by positioning the drive shaft coaxially with the stir pin. This inversion eliminates the bending moment generated by offset shafting, as the drive force now acts along the central axis of the stir pin rather than from the side, thereby resolving the contradiction between achieving displacement control and avoiding harmful bending moments.
Solution Approach 2:
The patent employs asymmetric positioning of the drive components relative to the stir pin, specifically placing the drive shaft concentrically within the stir pin structure. This asymmetric internal arrangement allows the drive mechanism to be embedded without creating external bending moments, maintaining welding position accuracy while achieving precise displacement control through the coaxial configuration.
2Manufacturing precision
If passive displacement adjustment with pressure sensor feedback is used, then displacement control is achieved, but hysteresis problems occur
Solution Approach 1:
The patent replaces the passive mechanical feedback system using pressure sensors with an active control system that directly actuates the drive mechanism. By substituting the indirect pressure-sensor-based feedback with direct mechanical actuation through the coaxial drive shaft, the system eliminates hysteresis losses associated with sensor feedback loops while maintaining precise displacement control.
3Ease of manufacture
If conventional friction stir spot welding is used, then welding process is simple, but keyhole remains in center of welding point
Solution Approach 1:
The patent segments the welding tool into distinct functional components: a stir pin for material mixing and a coaxially positioned drive shaft for controlled actuation. This segmentation allows the stir pin to perform its welding function while the separate drive shaft mechanism enables precise control and elimination of keyhole formation, thereby improving welding quality without significantly complicating the overall process.
Solution Approach 2:
The coaxial drive shaft acts as an intermediary mechanism between the power source and the stir pin. This intermediary component transmits controlled displacement and force to the stir pin, enabling precise control over the welding process that eliminates keyhole formation while maintaining relative simplicity through the direct coaxial transmission path.
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 coaxial drive system resolves bending moment issues, enhances welding precision, and ensures high-quality joints with minimal deformation and energy efficiency.
Implementation Method 1
friction stir spot welding is a novel solid-state welding technology developed based on friction stir welding technology
Data Source
AI summary
The present disclosure relates to a refill friction stir spot welding device. The refill friction stir spot welding device includes: a stir pin assembly including a stir pin; a stir sleeve assembly including a stir sleeve, the stir sleeve being sleeved outside the stir pin, the stir sleeve having a same axis as the stir pin; and an axial drive assembly and a rotary drive assembly, the axial drive assembly driving the stir pin and the stir sleeve, respectively, to move along the axis, the rotary drive assembly driving the stir pin and the stir sleeve to perform a rotational motion centered on the axis, a center axis of the axial drive assembly and a rotary axis of the rotary drive assembly are both located on the axis.