Diagnosis of threaded joints using acoustic waves

Abstract

The paper deals with modern methods of acoustic diagnostics of parts. Using of acoustic waves in the diagnosis of threaded connections makes it possible to inspect assemblies, bolted connections during assembly, as well as to almost instantly to identify defective products, incorrect dimensions and other factors of rejection based on the acoustic frequency response. With a large variety of threaded parts, a significant variation in pitch and diametrical dimensions, the use of acoustic waves represents a new innovative approach to non-destructive testing of units in the assembly of mechanical engineering products. Purpose: Development of an algorithm for diagnostics of threaded connections when assembling units using acoustic waves. To control the details of the node, an acoustic method was used to take the frequency response with the construction of a neural network. To create a neural network, all dimensions of the parts were measured, acoustic diagnostics were carried out to remove frequency characteristics, and the obtained data were entered into the NeuroPro program. To obtain the frequency characteristics of the nodes, a device with two sensors was used. One of them worked for reception, the second sent a constant signal at the frequency of white noise. Each bolt assembly was modified by screwing the bolts to the nut 10º. The measurement was carried out with screwing the bolts in the positions: 0º, 10º, 20º. Using a neural network, data on the degree of tightening of the bolts of the node were obtained and divided into categories. The most significant of them have been identified. The experiment showed that it is enough to have 2 frequency filters in order to determine the dimensions with an accuracy of 0.03 mm. Building a neural network of parts and a prefabricated unit will allow to almost instantly identifying defective products, incorrect dimensions and other factors of rejection based on the acoustic frequency response. This technique can be used to control units, bolted connections during assembly.