OBRABOTKAMETALLOV Vol. 26 No. 3 2024 technology setting during assembly [17–19]. Ultrasound can also improve the quality of the joint by creating a greater axial force in it [20–23]. Most of the work in this field is aimed at creating ultrasonic instruments that ensure effective transmission of vibrations to a threaded element [24, 25]. Ref. [26] considers the influence of longitudinal ultrasonic vibrations on the assembly quality of threaded joints. It has been found that low-amplitude vibrations increase the reliability of tightening, while an increase in the amplitude of vibrations does not increase the torque of loosening without ultrasound. It also indicates that in the case of small tightening moments, ultrasound provides a gap, which indicates a decrease in assembly quality. The study [27], which was also carried out with a longitudinal orientation of vibrations, shows that after reaching a certain level of the vibration amplitude (6 µm), ultrasound practically does not affect the joint reliability. Refs. [24, 28] consider the application of ultrasonic vibrations of a different polarization — torsional and longitudinally bending. The studies showed that with torsional vibrations with an amplitude of only 1 µm applied to the joint, the torque of loosening was reduced by 2 times. The application of longitudinal bending vibrations also reduces the torque of loosening. No studies of such types of vibrations in the thread assembly have been found. Another widely used method that prevents the loosening of the threaded joint is using polymer materials in the joint, for example [29–35]. The method consists in applying adhesive or sealant to the screw surface, which, when twisted, is distributed over the gaps between the shapes of the external and internal threads. After curing, the polymer prevents the thread from loosening under the influence of operational loads. This method suggests no lock nuts, spring and locking washers, cotter pins, or other mechanical locking elements, which facilitates and simplifies the assembly and disassembly of units, equipment, and machines. The analysis of scientific papers identifies the following features: – using additional threaded joint elements complicates the design of the product and increases the complexity of assembly, while the main effect is resistance to loosening without increasing axial force; – the advantages of using ultrasonic technologies are no need to complicate the design of the joint and an opportunity to increase the axial force, while the disadvantage is the limited use due to the need to position the oscillating system coaxially with the thread, which is not always possible due to the dimensions and design of the product; – using polymers is the easiest way to lock threaded parts, but it does not make it possible to increase the axial force. In this regard, the purpose and objectives of the study are defined. The aim is to develop a technology for creating an adhesive threaded joint with high performance properties, using ultrasonic vibrations in the assembly process. In order to achieve the goal, the following tasks have been solved: – investigating the effect of ultrasonic vibrations of shear polarization (perpendicular to the thread axis) on the parameters of the threaded joint; – investigating the effect of ultrasonic treatment on the properties of the polymer; – investigating the process of making a threaded joint assembled by the application of ultrasonic vibrations. Procedure of experimental research The experimental studies were conducted in three stages. The first stage evaluated the influence of shear ultrasonic vibrations on the assembly of the threaded joint. The second stage studied the effect of ultrasonic treatment on the properties of epoxy adhesive. In the third stage, the joint was assembled while adding adhesive and imposing vibrations at the same time. The experimental results were processed using the Statistica program.
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