SMA Filament Interlock Crimping for Precise Length Control
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Solution Overview
Problem
Existing crimping technologies face challenges in effectively crimping finer gauge shape memory alloy (SMA) filament wires, often distorting or damaging the filament, and fail to maintain consistent tensile stress and precise length control, which is critical for length-critical actuator applications.
Innovation Solution
The development of an SMA Interlock Assembly with interlocking features that include a male and female portion, where the male portion deforms and expands to fill the female portion during crimping, creating cold welding and high friction forces to secure the filament, and a bridge design with constraints on both sides to prevent slippage and maintain mechanical and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional crimping techniques are used on finer gauge SMA filament wires, then the crimping process can be performed, but the filament is distorted or damaged and tensile strength is reduced
Solution Approach 1:
The patent applies parameter changes by controlling the crimping temperature to be below the transformation temperature of the SMA filament, and by precisely controlling the crimping force and duration. This allows the filament to be crimped without exceeding the parameters that would cause distortion or damage, thereby maintaining tensile strength while enabling the crimping process.
Solution Approach 2:
The patent employs beforehand cushioning by using a crimping tool with controlled force application and by pre-setting the crimping parameters to avoid excessive force. The tool design includes features that distribute pressure evenly and prevent concentration of stress that would lead to filament damage before the crimp is complete.
2Productivity
If conventional crimping techniques are used on finer gauge SMA filament wires, then the crimping process can be performed, but precise length control is not maintained
Solution Approach 1:
The patent implements feedback control by incorporating sensors that monitor the crimping process parameters such as force, temperature, and duration. This feedback allows real-time adjustment of the crimping parameters to maintain precise length control, ensuring that the filament length remains within specified tolerances while still enabling the crimping process to proceed.
Solution Approach 2:
The patent applies dynamics by using a crimping tool with adjustable and controllable parameters that can be dynamically modified during the crimping process. The tool can adapt the crimping force and duration based on the specific filament being crimped, allowing precise length control while maintaining productivity across different filament types and gauges.
3Ease of manufacture
If existing crimping equipment is used for SMA filaments, then the crimping process can be performed, but the equipment is not optimized for fine gauge wires and requires additional infrastructure changes
Solution Approach 1:
The patent achieves universality by designing a crimping tool that can handle multiple filament gauges and types through adjustable parameters and interchangeable components. The tool is designed to be compatible with existing equipment while incorporating specialized features for fine gauge SMA filaments, thereby maintaining ease of manufacture without requiring extensive infrastructure changes or increasing device complexity.
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 solution enhances the reliability and consistency of SMA wire crimps, ensuring long-term mechanical and electrical integrity by preventing distortion and maintaining precise filament length, while being compatible with existing industry-standard equipment to minimize infrastructure changes.
Implementation Method 1
creating cold welding and high friction forces to secure the filament
Implementation Method 2
creating cold welding and high friction forces to secure the filament
Implementation Method 3
SMA generally comprises a metal that is capable of 'remembering' or substantially reassuming a previous geometry. For example, after it is deformed, it can either substantially regain its original geometry by itself during e.g., heating (i.e., the 'one-way effect') or, at higher ambient temperatures, simply during unloading (so-called 'pseudo-elasticity').
Data Source
AI summary
Apparatus and methods for filament crimping. The apparatus includes a filament crimp element. The filament crimp element includes a first set of cavities disposed at a spacing which creates a first set of features and a second set of cavities disposed at a spacing which creates a second set of features. The first and second set cavities are substantially opposite one another. The first set of features are adapted to be placed at least partially within the second set of cavities and the second set of features are adapted to be placed at least partially within the first set of cavities. Interlock features configured for cold welding are also included. Methods for the manufacture of the device are also disclosed. In addition, methods for automated placement and manufacture of assemblies using the crimp elements are also disclosed.