Piezoelectric Polymer Sensor for Crimp Force Measurement
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Solution Overview
Problem
Traditional crimp force monitors (CFMs) are inadequate for lighter gauge wire crimping applications due to low output signals, shunting effects, and reduced sensitivity, which makes them insufficient for ensuring quality in modern automotive wire harness manufacturing where smaller wire gauges and lighter crimping forces are used.
Innovation Solution
A piezoelectric polymer film sensor device is integrated into a forming machine, with multiple films arranged symmetrically on a plate to minimize shunting and edge loading, providing enhanced sensitivity and signal-to-noise ratio, and featuring multiple output ranges and electronic signal processing to boost the signal level and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional piezoelectric force sensor rings are used for crimp monitoring, then they can detect crimp defects with adequate signal output for heavier gauge wires, but they produce insufficient output signal and reduced sensitivity for lighter gauge wire crimping applications
Solution Approach 1:
The patent changes the material parameter from traditional piezoelectric ceramics to piezoelectric polymer, which has higher piezoelectric coefficients and generates stronger electrical signals for the same mechanical stress. This material substitution directly addresses the insufficient signal output problem while maintaining measurement precision across different wire gauges
Solution Approach 2:
The patent employs a composite structure combining piezoelectric polymer material with a flexible substrate or mounting mechanism. This composite approach enhances both the signal generation capability and the adaptability to different crimping forces, resolving the contradiction between sensitivity and reliable signal output
2Measurement precision
If traditional CFM arrangements are used, then they can monitor crimping forces, but shunting effects occur that reduce sensitivity and repeatability
Solution Approach 1:
The patent introduces an intermediary flexible mounting mechanism between the force sensor and the crimping tool. This intermediary element distributes the mechanical stress more uniformly across the sensor surface, eliminating shunting effects and improving both sensitivity and repeatability by ensuring consistent force transmission
3Measurement precision
If traditional CFMs are used for lighter gauge wires, then they can provide monitoring capability, but the signal to noise ratio is very low making the signal difficult to distinguish from noise
Solution Approach 1:
The patent changes the piezoelectric material to polymer-based materials with higher piezoelectric coefficients, which generate significantly stronger electrical signals for the same crimping force. This parameter change increases the signal amplitude well above the noise floor, improving the signal-to-noise ratio and making signal distinction reliable
Solution Approach 2:
The patent replaces traditional mechanical force ring sensors with a piezoelectric polymer-based sensing system that converts mechanical stress directly into electrical signals with higher gain. This substitution inherently amplifies the useful signal while maintaining low noise levels, resolving the signal distinguishability issue
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 solution significantly improves sensitivity, repeatability, and signal-to-noise ratio, enabling accurate force measurement in lighter gauge crimping applications, reducing noise interference, and allowing for real-time quality determination without the need for additional monitoring devices.
Implementation Method 1
At least one piezoelectric polymer film is supported on the plate. The film provides an electrical output indicative of the force incident on the plate.
Data Source
AI summary
A sensor device includes at least one piezoelectric polymer film supported on a plate that is positioned relative to a machine such that a force used during a manufacturing process involving the machine is incident on the plate. The piezoelectric polymer film provides an electrical output indicative of the incident force. In a disclosed example, a single piezoelectric polymer film extends across a substantial portion of a surface area of the plate. In another disclosed example, a plurality of piezoelectric polymer film sensor elements area are arranged symmetrically about a location where the incident force is expected to be most prominent.