Method for calibrating pre-tightening force of external thread fastener with sensor

Abstract

The invention provides a method for calibrating a pre-tightening force of an external thread fastener with a sensor. The method comprises the following steps: carrying out temperature correction on each ultrasonic flight time delta tnact' by using a reference temperature; establishing a function fitting relation between an acoustic time difference delta tnkorr'-delta t0korr after temperature correction and different loads Fn and acquiring a fitting equation of a pre-tightening force F relative to the acoustic time difference after temperature correction. Therefore, a measurement result with high reliability can be obtained during measurement.

Description

technical field [0001] The invention relates to the field of pretightening force detection of fasteners, in particular to a method for calibrating the pretightening force of external threaded fasteners with sensors. Background technique [0002] At present, by preparing sensors / transducers on externally threaded fasteners, the technology of measuring the pretightening force of externally threaded fasteners by using ultrasonic signals excited by the sensor / transducer has a good application prospect. The technology mainly includes three aspects: [0003] 1. Fix, deposit and grow the piezoelectric sensor on the head of the externally threaded fastener or the end of the rod by pasting / welding / vacuum plating; [0004] 2. Calibrate the externally threaded fasteners with sensors according to a certain method. The calibration process may include determining the measurement parameters of externally threaded fasteners, environmental parameters, and ultrasonic signal parameters excit...

AI Technical Summary

Problems solved by technology

[0007] 1. The parameters considered are incomplete, which reduces the credibility of the calibration results, such as the influence of temperature on the length change of externally threaded fasteners, the thickness of the interlayer of the specific installation structure, and the characteristics of the nut, etc.;

[0008] 2. The measurement parameters are redundant, which increases the complexity and cost of the calibration process, such as measuring elongation, etc.;

[0009] 3. The measurement method is unreasonable, and the influencing factors of mutual interference are not considered separately, resulting in low reliability of the results

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