Rotary Cutting with Ultrasonic Vibration of Hardened Steel

We propose ultrasonic rotary cutting, in which ultrasonic vibrations are imparted to a rotating cemented carbide cylindrical tool to cut hardened steel to reduce the cutting resistance and improve the properties of the machined surface, and investigate the machining characteristics. Machining experiments were conducted under dry and wet conditions to verify the effects of the ultrasonic vibrations. The surface produced via ultrasonic rotary cutting was intermittently machined, which is characteristic of ultrasonic cutting. In dry machining, the cutting resistance was reduced by approximately 20%, and the surface roughness of the machined surface was reduced by approximately 30% when the cutting speed was below the critical speed. We also demonstrated that the surface roughness was improved by ultrasonic vibrations when the cutting speed was equal to or above the critical speed. A similar tendency was observed in wet machining with longer cutting lengths. We then applied ultrasonic rotary cutting to machine a straight R groove in hardened steel and showed that the cutting resistance was reduced, and the tool engagement was improved.

Development of Ultrasonic Vibration-Assisted Magnetic Compound Fluid (MCF) Polishing Technology

This study investigates the development of an ultrasonic vibration-assisted magnetic compound fluid (MCF) polishing technology for final polishing. The fabrication of an experimental apparatus entails an ultrasonic polishing unit, and the experimental investigation of its performance in surface polishing is described. In addition, ultrasonic vibration-assisted MCF polishing under different applied methods of ultrasonic vibration is studied. The experimental results indicate that applying ultrasonic vibration to the workpiece improves the surface roughness and material removal rate when the ultrasonic vibrations are changed. In addition, across the range of polishing conditions employed in this study, the precision surface roughness and high material removal rate can be easily obtained on the acrylic plate by applying an elliptical vibration to the ultrasonic vibration.

Investigation of Traps in AlGaN/GaN Heterostructures by Ultrasonic Vibrations

A method of dynamic deformations has been proposed as a useful informative tool in the characterization of transportation properties of a two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures. It is found that the exposing of a sample to ultrasonic vibrations results in the persistent acousto-conductivity (PAC) which was observed up to room temperatures. The PAC behaves itself like persistent photoconductivity (PPC), and the carrier density in the 2DEG channel is primarily contributed by the transfer of electrons excited from traps (like DX centers) as a result of their reconstruction under the ultrasonic loading.

RESEARCH OF THE ULTRASONIC DRYING PROCESS OF VARIOUS MATERIALS

В статье рассматривается процесс конвективной сушки тканых материалов и продуктов растительного происхождения. Показано, что длительность процесса может быть уменьшена за счет дополнительного воздействия ультразвуковыми колебаниями высокой интенсивности. Для определения ускорения процесса сушки ультразвуковыми колебаниями были разработаны лабораторные установки, позволяющие организовать комбинированное воздействие потока теплого воздуха и ультразвуковых колебаний. Комбинированная сушка ткани проводилась при трех различных температурах сушильного агента. Было установлено, что сокращение времени процесса по сравнению с конвективной сушкой зависит от температуры сушильного агента и составляет от 10% при температуре 40 0C до 20% при температуре 60 0C. В свою очередь, сушка овощей проводилась на резонансных промежутках от излучающего диска, при этом овощи нарезались толщиной 5 мм и располагались тонкими слоями. Комбинированная сушка моркови и картофеля позволила достичь сокращения времени сушки на 45-47%. При этом затраты на электроэнергию для ультразвукового аппарата составляют не более 30% от затрат на конвективную сушку. В результате проведенной работы была показана эффективность применения комбинированной ультразвуковой и конвективной сушки прежде всего для обезвоживания овощей, тогда как для ткани эффект не столь очевиден. Лабораторные исследования проводились при малом объеме высушиваемого материала, из-за слабого проникновения ультразвуковых колебаний на большую глубину, поэтому дальнейшие исследования необходимо направить на разработку полупромышленных и промышленных сушильных аппаратов для ультразвуковой сушки овощей и других термолабильных материалов. The article deals with the process of convective drying of fabrics and vegetables. The duration of the process can be reduced by additional exposure to high-intensity ultrasonic vibrations. To carry out drying, laboratory installations were developed that allow organizing the combined effect of a stream of warm air and ultrasonic vibrations. The combined drying of the fabric was carried out at three different temperatures of the drying agent and it was noted that the greatest reduction in drying time compared to convective drying was achieved at a temperature of 60 ° C. Although the overall reduction in drying time ranged from 10% to 20% depending on the temperature of the air flow. Drying of vegetables was carried out at resonance intervals from the emitting disk, while vegetables were cut 5 mm thick and placed in thin layers. Combined drying of carrots and potatoes made it possible to achieve a reduction in drying time of 45-47%. In this case, the cost of electricity for the ultrasonic apparatus is a small part of the cost of convective drying. As a result of the work carried out, it is possible to draw conclusions about the effectiveness of the use of combined ultrasonic and convective drying for dehydration of vegetables, while the effect is not so obvious for tissue. Laboratory studies were carried out with a small volume of dried material, due to the weak penetration of ultrasonic vibrations to a great depth, therefore, further research should be directed to the development of semi-industrial and industrial dryers for ultrasonic drying of vegetables and other heat-sensitive materials.

Assembly features of threaded fastenings having various sizes when using shear ultrasonic vibrations

The problems that arise from threaded fastenings assembly have been considered. A promising direction for solving emerging problems has been found. Research results of the effect of shear polarization ultrasonic vibrations on the parameters of the threaded fastenings are presented.

Intensification of heat exchange by an ultrasound source for milk pasteurization.

The goal of this article is to investigate the effect of ultrasonic vibrations on the process of milk pasteurization. Ultrasound can potentially intensify heat transfer and reduce the formation of thermal sediment (soot deposit) on the walls of heat-exchange devices. The paper presents the results of experimental studies demonstrating the growth rate of thermal sediment on the wall of the heat-exchange apparatus and its amount in the volume of milk under the influence of ultrasonic vibrations and without it.

Use of the toolholder with the oriented stiffness for ultrasonic turning

An effective way of processing difficult-to-machine materials is ultrasonic cutting, which is carried out by applying ultrasonic vibrations to the movement of the cutter and contributes to a significant reduction in cutting force and increase processing productivity. The article presents the results of research on the efficiency of using a new device for ultrasonic cutting with an electrostrictive vibrating drive. The source of ultrasonic vibrations is an electrostrictive vibratory drive, which provides oscillations in the range of 10 - 20 kHz with amplitude of 10 - 15 microns. Experimental studies have confirmed the effectiveness of the proposed design of the toolholder to transmit the wave of ultrasonic vibrations almost perpendicular to the axis of the vibratory drive, which allows you to unload the vibrating drive from the cutting force and use vibration pulses only to deform elastic elements by the amplitude of ultrasonic vibrations. The device provides conditions for processing of difficult-to-process materials, allows increasing accuracy of processing of details, to reduce roughness of the processed surfaces and to increase productivity of processing.

ENSURING THE MAXIMUM EFFICIENCY OF ULTRASONIC TECHNOLOGIES IN MEDIA WITH A LIQUID PHASE

Актуальность исследований обусловлена отсутствие единого подхода к обеспечению ультразвукового воздействия с максимальной эффективностью при реализации различных технологических процессов в жидкодисперсных средах. Целью исследований является выявление условий обеспечения оптимальных режимов реализация различных технологических процессов под действием ультразвуковых колебаний в средах с преимущественно жидкой фазой с учетом особенностей, связанных с формированием ультразвуковых колебаний, их введением в различные по свойствам среды и реализацией самого воздействия с максимальной эффективностью. В качестве объекта исследований выступают ультразвуковые технологические аппараты для воздействия в режиме «развитой» кавитации с целью интенсификации технологических процессов в дисперсных средах с преимущественно жидкой фазой. В результате исследований на основе анализа формирования «развитой» кавитации выявлены наиболее эффективные режимы формирования колебаний, их введения в обрабатываемые среды и обеспечения максимально эффективного кавитационного воздействия, обеспечивающего заданные преобразования структуры и свойств обрабатываемых сред при воздействии на ограниченные и «безграничные» технологические объемы, воздействии в режиме стоячей волны и воздействии в тонких слоях жидкости. Проведенные исследования позволили выработать и рекомендовать для практического применения общий алгоритм управления ультразвуковым воздействием при реализации технологических процессов в дисперсных средах с преимущественно жидкой фазой за счет непрерывного изменения в режиме реального времени частоты и уровня напряжения электронного генератора, питающего ультразвуковую колебательную систему. The relevance of research is due to the lack of a unified approach to providing ultrasonic exposure with maximum efficiency in the implementation of various technological processes in liquid-dispersed media. The aim of the research is to identify the conditions for ensuring optimal modes for the implementation of various technological processes under the action of ultrasonic vibrations in media with a predominantly liquid phase, taking into account the peculiarities associated with the formation of ultrasonic vibrations, their introduction into media of different properties and the implementation of the action itself with maximum efficiency. The object of research is ultrasonic technological devices for exposure in the "developed" cavitation mode in order to intensify technological processes in dispersed media with a predominantly liquid phase. As a result of studies based on the analysis of the formation of "developed" cavitation, the most effective modes of formation of oscillations, their introduction into the processed media and provision of the most effective cavitation effect, providing the specified transformations of the structure and properties of the processed media when exposed to limited and "unlimited" technological volumes, exposure in a standing wave mode and exposure to thin layers of liquid. The studies carried out made it possible to develop and recommend for practical application a general algorithm for controlling ultrasonic action in the implementation of technological processes in dispersed media with a predominantly liquid phase due to a continuous change in real time of the frequency and voltage level of the electronic generator supplying the ultrasonic oscillatory system.