Impact Fastening Tool Seating Determination via Vibration Frequency Analysis
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Solution Overview
Problem
Existing impact fastening tools face challenges in accurately determining fastener seating with a small calculation load, often requiring high-resolution sensors and significant computational resources to mitigate noise and digit cancellation.
Innovation Solution
The impact fastening tool employs a frequency-based approach, utilizing a signal obtainer and seating determiner that analyze the hitting frequency of the hammer before and after fastener seating, with a filter and frequency converter to extract the reference frequency signal, allowing for accurate seating determination with a reduced calculation load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque variation ratio calculation method is used to determine fastener seating, then seating determination can be performed, but high-resolution torque sensor and high-spec calculator are required to suppress errors from noise and cancellation of significant digits
Solution Approach 1:
The patent replaces the mechanical torque measurement system with an acoustic vibration detection system. Instead of using high-resolution torque sensors to measure torque variations, the invention uses acoustic sensors to detect vibration signals generated during the fastening process. The seating determination is made by analyzing changes in vibration frequency and amplitude characteristics, substituting complex mechanical measurement with simpler acoustic detection.
Solution Approach 2:
The patent introduces vibration signals as an intermediary parameter to indirectly indicate fastener seating status. Rather than directly measuring torque variations, the system uses vibration frequency and amplitude as intermediate indicators that correlate with seating state. This intermediary approach simplifies the measurement system while maintaining determination accuracy.
2Measurement precision
If moving mean values of tightening torque are calculated to obtain torque variation quantity and ratio, then seating can be determined, but a large calculation load is required to handle noise and significant digit cancellation
Solution Approach 1:
The patent extracts only the essential vibration frequency and amplitude characteristics from the complex torque signal processing. Instead of calculating moving mean values, torque variation quantities, and ratios as in conventional methods, the invention directly extracts dominant vibration frequency components and their amplitude changes. This extraction approach maintains seating determination accuracy while dramatically reducing computational complexity.
Solution Approach 2:
The patent applies partial action by focusing only on the most critical vibration parameters (dominant frequency and amplitude) rather than performing complete torque signal analysis. By selectively monitoring only the essential vibration characteristics that indicate seating status, the system achieves adequate determination accuracy with minimal calculation load.
Data Source
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AI summary
An impact fastening tool (2) may include a motor (4); a hammer (6) configured to be rotationally driven by the motor; an anvil (8) configured to be hit in a rotational direction by the hammer; a signal obtainer (24,28) configured to obtain a variable signal which varies in accordance with a hit to the anvil by the hammer; and a seating determiner (30) configured to determine whether or not a fastener has been seated based on the variable signal obtained by the signal obtainer, wherein the seating determiner is configured to determine whether or not the fastener has been seated based on a signal component of the variable signal obtained by the signal obtainer, the signal component corresponding to a predetermined reference frequency.