Floating-Axle FSW Head for Accurate Axial Force Sensing
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Solution Overview
Problem
Existing friction stir welding (FSW) heads face challenges in accurately measuring axial forces, which are crucial for proper calibration and control of the welding process, often resulting in inefficiencies and higher costs due to the need for multiple heads for rotating and stationary shoulder configurations.
Innovation Solution
A compact FSW head with a floating axle and load cell positioned at the bottom, allowing for accurate axial force measurement and easy serviceability, enabling seamless transition between rotating and stationary shoulder configurations without disassembly, and eliminating the need for external spindle drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional FSW head design with external spindle drive is used, then the structure is simpler, but the axial force measurement accuracy deteriorates and the device size increases
Solution Approach 1:
The patent merges the load cell, axle, and motor assembly into a single integrated head structure. The load cell is positioned at the bottom of the head to directly measure axial forces, while the axle extends through the load cell to connect the tool to the motor assembly. This integration eliminates the need for separate external spindle drives and improves measurement accuracy by placing the sensor within the force transmission path.
Solution Approach 2:
The load cell acts as an intermediary element between the tool and the head housing. It is positioned in the axial force path to directly sense the forces applied during welding. The floating axle design allows the load cell to measure forces without being constrained by the head housing, providing accurate measurements while maintaining structural integrity.
2Adaptability or versatility
If multiple FSW heads are used for rotating and stationary shoulder configurations, then the adaptability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent implements a dynamic configuration system where the shoulder can be easily changed from rotating to stationary type. The head housing includes a configurable shoulder assembly that can be adjusted or replaced based on welding requirements. This dynamic adaptability allows a single head to perform multiple functions that would traditionally require separate dedicated heads.
Solution Approach 2:
The FSW head is designed with universal functionality to accommodate both rotating and stationary shoulder configurations. The motor assembly can drive the shoulder to rotate, or the shoulder can be configured to remain stationary while the pin rotates. This multi-functionality is achieved through a configurable shoulder assembly that integrates with the universal head structure, eliminating the need for multiple specialized heads.
3Measurement precision
If the load cell is positioned at the top of the head, then the axial force measurement is easier, but the risk of collisions and structural deviations increases
Solution Approach 1:
Instead of positioning the load cell at the top of the head as in traditional designs, the patent inverts the configuration by placing the load cell at the bottom of the head housing. This inversion positions the sensitive measurement element away from collision-prone areas while maintaining its ability to measure axial forces through the floating axle mechanism. The load cell remains in the force path but is protected from external damage.
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
This design provides improved axial force measurement accuracy, reduces operational costs, and allows for efficient reconfiguration between shoulder types, enhancing the quality and efficiency of welds while minimizing the risk of collisions and structural deviations.
Implementation Method 1
the load cell generates load signals in response to the upward forces
Implementation Method 2
a motor assembly configured to rotate the axle within the bore and with respect to the head housing
Implementation Method 3
a lower bearing enables the axle to rotate with respect to the head housing and the lower bearing is either coupled to the inner ring via one or more floating components or formed with the inner ring and the one or more floating components, so that the upward forces on the shoulder translate to the inner ring via the lower bearing and the one or more floating components
Implementation Method 4
the workpiece(s) are plasticized by frictional heat generated by rotation of the FSW tool
Data Source
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AI summary
The friction stir welding head (10) presented herein includes a head housing (100) and an axle (202). The head housing (100) extends from a top end (102) to an open bottom end (104) and defines a bore (106) extending between the top end and the open bottom end. The axle (202) is coaxial with and rotatable within the bore (106). The axle (202) is also laterally secured within the head housing (100) and axially movable with respect to the head housing. Still further, the axle (202) includes an engagement end (204) that extends beyond the open bottom end (104) of the head housing (100). The engagement end (204) supports a friction stir welding tool (280) that is configured to rotate with the axle (202) to effectuate friction stir welding operations. The friction stir welding head (10) may also include a load cell (250) configured to generate load signals in response to axial movement of the axle (202).