Chatter Vibration Determination Using Dynamic Phase Difference Thresholds
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Solution Overview
Problem
Existing methods for distinguishing between regenerative and forced chatter vibrations in machine tools are prone to errors, particularly at low rotation speeds and chatter frequencies, leading to incorrect identification of vibration types, which can result in inadequate suppression of chatter vibrations and tool damage.
Innovation Solution
A vibration determination method that calculates specific frequency ranges and determination validity based on rotation speed and frequency resolution to accurately differentiate between regenerative and forced chatter vibrations, including rotational-period and flute-passage-period forced chatter vibrations, using formulas to define these ranges and validity thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the phase difference range for determining forced chatter vibration is defined by two constants, then the determination method is simple, but the accuracy deteriorates at low rotation speeds and low chatter frequencies
Solution Approach 1:
The patent applies dynamics by making the determination thresholds dynamic rather than static. Instead of using fixed constant ranges for phase difference determination, the invention calculates adaptive thresholds based on detected rotation speed and chatter frequency. This allows the determination criteria to automatically adjust to different operating conditions, improving accuracy at low rotation speeds and frequencies while maintaining simplicity through algorithmic calculation.
Solution Approach 2:
The invention changes the parameters used for determination from fixed constants to variable parameters derived from actual detection data. By calculating determination thresholds based on rotation speed S and chatter frequency FC, the system transforms static determination criteria into dynamic ones that adapt to changing processing conditions, thereby resolving the accuracy problem at low speeds and frequencies.
2Adaptability or versatility
If the determination range is widened to cover more cases, then more forced chatter vibrations can be detected, but regenerative chatter vibrations may be erroneously identified as forced chatter vibrations
Solution Approach 1:
The patent applies partial action by introducing a determination validity parameter that partially validates the forced chatter vibration determination. Instead of making a binary decision based solely on phase difference, the system calculates a validity score that considers the relationship between the detected phase difference and the calculated determination thresholds. This allows the system to maintain wide detection coverage while filtering out erroneous determinations through the validity assessment.
Solution Approach 2:
The invention implements feedback by using the calculated determination validity to adjust the final determination outcome. The system continuously monitors whether the detected phase difference falls within the calculated thresholds, computes the validity based on this relationship, and uses this feedback to confirm or reject the forced chatter vibration determination, thereby preventing erroneous identifications.
3Measurement precision
If detection resolution and frequency resolution are improved, then determination accuracy is enhanced, but the error range calculation becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-calculating the determination thresholds and error ranges based on the detected rotation speed and chatter frequency before making the final determination. The system computes the expected phase difference ranges and validity thresholds in advance, using the detection resolutions as input parameters. This preliminary calculation simplifies the final determination process while incorporating the effects of detection precision.
Data Source
AI summary
When generation of a chatter vibration is detected, a parameter calculation device calculates a first frequency range and a second frequency range. A determination validity is calculated in consideration of a rotation speed detection resolution and a frequency resolution, and based on a ratio of a frequency range of rotational-period forced chatter vibration to a frequency range of regenerative chatter vibration. It is determined based on the determination validity whether the generated chatter vibration is regenerative chatter vibration, rotational-period forced chatter vibration, or flute-passage-period forced chatter vibration.