Longitudinal Ultrasonic Vibration Research Articles

Sustainable drilling process of 1045 steel plates regarding minimum energy consumption and desired work quality

Green manufacturing technologies comprising low energy processes with minimum environmental pollution are progressive issues that considered by the researchers and various industries during last decades. The aim of current work is to study effect of longitudinal ultrasonic vibration and minimum quantity lubrication on drilling force, surface roughness and burr height. For this purpose series of experiment are designed based on response surface methodology to analyze effect of vibration amplitude, mist flow rate, cutting speed and feed rate on machining power, exit burr height and surface roughness. Analysis of variances was also performed to identify which factor has great impact on process quality characteristic. Results indicated that the most influential factor for cutting force, surface roughness and burr height are feed rate, vibration amplitude and spindle speed, respectively. Also, setting of 10 μm vibration amplitude, 190 mL/h flow rate and 910 rpm spindle speed and 80 mm/min feed rate causes 98% desirability in multi response optimization.

Study on effects of ultrasonic vibration on sliding friction properties of PTFE composites/phosphor bronze under vacuum

This paper is a tribological problem extracted from the application of the ultrasonic motor under the vacuum. Nine frictional states were designed. Under the atmosphere and vacuum environment, the effects of longitudinal and torsional ultrasonic vibration modes on the sliding friction pair of phosphorus bronze and Polytetrafluoroethylene (PTFE) composites were studied. The results show that under vacuum, applying vertical or horizontal ultrasonic vibration can reduce the friction coefficient. However, comparing with sliding friction under ultrasonic vibration in atmosphere, the friction coefficient increases. With the increase of vacuum degree, the effect of friction reduction by ultrasonic vibration becomes weaker, which leads to the increases of the friction coefficient under high vacuum. The friction coefficient is almost no change under low excitation voltage. It is revealed that the increase of friction coefficient caused by ultrasonic vibration in vacuum is due to the decrease of air medium density, the reduction of acoustic levitation force and the increase of contact opportunity of friction pair.

The Improvement Effect and Mechanism of Longitudinal Ultrasonic Vibration on the Injection Molding Quality of a Polymeric Micro-Needle Array.

A polymeric micro-needle array with high quality has been fabricated using a longitudinal ultrasonic-assisted micro-injection molding (LUμIM) method. To realize the practicability and stability in actual industrial processing, this paper is aimed at studying the improvement mechanism of ultrasonic vibration on the molding quality. The melt-filling process in the micro-needle array cavity is simulated, and the improvement effect of ultrasonic vibration is discussed. The enhancement effect of ultrasonic vibration on material properties of polypropylene and polymethylmethacrylate parts are experimentally investigated. The results show that in the manufacturing of the micro-needle array part using LUμIM, the mold-filling quality is improved by the enhanced melt filling capability and pressure compensation effect, which are caused by the increased corner viscosity gradient, reduced the filling time and melt viscosity under ultrasonic vibration. Material properties of both the semi-crystalline polymer and amorphous polymer could be enhanced by the transformation of micromorphology. It is proved that for a semi-crystalline polymer, this novel method could be employed as a material properties enhancement method, and an optimal excitation voltage of ultrasonic vibration is obtained to achieve the best material properties.

Applying ultrasonic vibration during single-point and two-point incremental sheet forming

Abstract Ultrasonic assisted (UA) deformation has been studied on a variety of materials in both fundamental tensile and compression tests as well as in relevant industrial processes. Reductions in flow stress are a common observation when applying UA during material plastic deformation. The objective of this work is to study the effects of ultrasonic energy on single-point (SPIF) and two-point (TPIF) incremental forming. A longitudinal ultrasonic vibration is applied to a hemispherical ISF tool at 20kHz oscillating frequency. A series of conical shapes were selected for UA-SPIF and a 45° conical shape backing die is selected for UA-TPIF. Generally, a positive correlation between oscillation amplitude and reduction in forming forces is observed in the investigated conditions. The force reduction in UA-TPIF is much more significant compared with UA-SPIF. It is hypothesized that UA-SPIF allows membrane vibration of the entire sheet, which lowers the effective ultrasonic energy input into the local plastic deformation region. In addition, UA-TPIF shows a local sheet thickness reduction in regions where ultrasonic oscillation is applied.

Analytical and experimental study of an ultrasonic horn with a bend angle

An ultrasonic horn is a key component in power ultrasonic longitudinal vibration systems, and the most common horns are designed to allow vibration to travel along a single straight axis. However, change of the propagation direction is required in such applications as ultrasonic cleaning of the inner surface of a bent pipe, ultrasonic-assisted turning for a deep concave workpiece, and ultrasonic bone cutting devices. To address this requirement, this work proposes an angled horn comprising two uniform rods of finite length, which can be excited to resonate in longitudinal mode to change the propagation direction of a longitudinal vibration. Experimental comparison of the working frequencies of the designed and fabricated angled horns validated the effectiveness of the proposed design method. Experimental tests also showed that longitudinal vibration excited by a transducer along the axial direction was successfully transferred from the input end to the output end via the angled horn. Furthermore, the linear vibration characteristics of nine prototype vibration systems (composed of one transducer and nine angled horns) were obtained by measuring the vibration amplitudes induced by various excited voltages applied to the transducer.

Study on a longitudinal–torsional ultrasonic vibration system with diagonal slits

The longitudinal–torsional ultrasonic vibration machining process is popular for machining hard and brittle materials. A longitudinal–torsional ultrasonic vibration system with diagonal slits was designed for the ultrasonic vibration machining process based on the principle of acoustics propagation in this study. Four uniform diagonal slits were cut off on the horn cylinder to transform the longitudinal ultrasonic vibration into a longitudinal–torsional composite motion. A finite element analysis was used to optimize the mechanical structure of the vibration system. Dynamic characteristics of the vibration system were numerically studied, and the relationship of diagonal slits versus the resonance frequency and amplitudes of longitudinal–torsional vibration was analyzed, so that the longitudinal–torsional output amplitude can be optimized by rational choice of structure parameters of diagonal slits. Moreover, the movement locus of the system output end was obtained by utilizing the Origin software, which was proved to be elliptical, and the accuracy of the finite element model was confirmed by comparing numerically and experimentally determined resonant characteristics. In addition, the verification of longitudinal–torsional ultrasonic vibration was proved for the designed ultrasonic vibration system.

초음파 진동을 이용한 RFID 미세패턴 성형

In this study, we developed a process technology to fabricate RFID tag antennas using a one-sheet inlay micro-pattern forming process by press-molding RFID tag antennas on insulation sheet layers, such as polymer films, using ultrasonic longitudinal vibration. In addition, a fine pattern applicable for RFID tag antennas was manufactured using a 25 μm thick thin-plate square wire; this is in contrast to the method that uses a conventional round wire. The developed ultrasonic indentation process can be used to fabricate fine pattern of the RFID antenna using one piece of equipment. The simplified manufacturing process technology has a shorter manufacturing time and is more economical. The developed RFID tag antenna forming technique involves pressing the 25 μm square wire directly on the thin sheet insulation sheet of maximum thickness 200 μm, using a 60 kHz ultrasonic tool horn.

Ultrasonic assistance in drilling: FEM analysis and experimental approaches

Conventional drilling (CD) which is known by two constant rotary and linear motions causes some problems in drilling of materials such as high thrust force, poor surface quality, and rapid tool wear. To get rid of these problems or at least minimize them, a promising technology has been employed in the recent years, where vibrations usually with low amplitude and high frequency are applied to the direction of feed motion results in a time-dependent velocity between drill tip and workpiece. This paper focuses on the design of a vibratory tool following by experimental and numerical approaches to study the influence of longitudinal ultrasonic vibrations on drilling of aluminum alloy 7075. Experimental part is a comprehensive exercise to design, fabricate, and test a system equipped with different instruments to work in desired conditions. Experimental results are supported by a finite element method to better comprehend what is happening in cutting process when ultrasonic vibrations are added. The achieved results prove that using ultrasonic-assisted drilling (UAD), the machining ability of drilled aluminum workpiece can enhance significantly. Improvement of up to 40% for drill circularity and a reduction of up to 37% in thrust force were achieved.

ВЛИЯНИЕ УЛЬТРАЗВУКОВОЙ МЕХАНОАКТИВАЦИИ НА КИНЕТИКУ КРИСТАЛЛИЗАЦИИ И МАРТЕНСИТНЫЕ ПРЕВРАЩЕНИЯ АМОРФНОГО СПЛАВА НА ОСНОВЕ TiNi

The influence of ultrasonic mechanical activation on the amorphous alloys is practically unstudied. The influence of ultrasound on crystallization of TiNi-based amorphous alloy ribbons, their structure and properties formation has not been investigated up to the present moment. Being in the crystalline state, TiNi-based amorphous alloys experience the thermoelastic martensitic transformations, which are the basis for manifestation of unusual mechanical properties – shape memory effect. Amorphous shape memory alloys are the advanced materials that experience thermoelastic martensitic transformations after crystallization. Such materials are used as the basis for the creation of crystalline materials with the specified parameters of crystalline structure or for producing the amorphous and crystalline composites. The goal of this work is the study of ultrasonic mechanical activation influence on the crystallization kinetics and martensitic transformations of an amorphous shape memory alloy using the differential scanning calorimetry (DSC) method. The ultrasonic mechanical activation was carried out using two methods: in the waveguide of longitudinal ultrasonic vibrations and in the ultrasonic anvil. During the first method of the ultrasound mechanical activation, the amorphous ribbon was fixed in the waveguide of longitudinal vibrations and experienced ultrasonic irradiation of various durations. To initiate ultrasonic vibrations, the authors used the UZDN-2T ultrasonic low-frequency dispergator with the frequency of 22 kHz. During the second method, the amorphous ribbon is placed horizontally and the vertically placed waveguide is applied using contact process. Such method is used for the surface strengthening of metals and alloys. To initiate the ultrasonic vibrations, the authors used the UZG 1-1 ultrasonic generator. Ti 50 Ni 25 Cu 25 amorphous ribbons were selected as a subject of the study. Calorimetric measurements were carried out using the Mettler Toledo 822e differential scanning calorimeter. The obtained data showed that in the result of ultrasonic mechanical activation, temperatures and energies of crystallization and martensitic transformations change that can be the evidence of size reduction of a crystalline phase grain.

An investigation of conventional and ultrasonic-assisted incremental forming of annealed AA1050 sheet

Studying the effect of longitudinal ultrasonic vibrations on the performance of incremental forming process of aluminum-1050 sheet is the main purpose of this paper. In this new technique, ultrasonic vibrations with high frequency and low amplitude are axially added to the movement of forming tool. To fulfill this purpose, a system was carefully devised. This system consists of different parts including a mechanism attached into the chuck of CNC machine to give rotary motion and also sent ultrasonic power to the vibratory tool. Straight groove test was performed, and various parameters including forming force and sheet formability were investigated in both conventional and ultrasonic-assisted incremental forming process. The achieved results show that ultrasonic assistance can increase formability and decrease forming force significantly.

Investigation of Ti-6Al-4V alloy acoustic softening

High power ultrasonic vibration is widely used for improving manufacturing processes such as machining and metal forming. High frequency mechanical vibration affects material properties and friction forces in contacting surfaces. Flow stress reduction under superimposed ultrasonic vibration is called as acoustic softening. The amount of this parameter should be determined for ultrasonic assisted metal forming processes. For determination of this parameter for workhorse Ti-6Al-4V alloy, experimental setup was designed and fabricated. Then tensile test under longitudinal ultrasonic vibration was performed for different ultrasonic powers. Results show that ultrasonic vibration has considerable effect on plastic behavior of the alloy and decreases flow stress. Also, increasing ultrasonic power leads to higher acoustic softening. Yield stress reduction up to 9.52%, ultimate stress reduction up to 4.55% and elongation up to 13% were obtained at 340W ultrasonic power. After applying ultrasonic vibrations and its termination, hardness of specimens were measured in which increase up to 9% was observed.

Parametric study and multicharacteristic optimization of rotary turning process assisted by longitudinal ultrasonic vibration

Turning with rotary tool is a newly developed alternative of the conventional turning process in which cutting edge of a round insert rotates about its axis, so that a continuously indexed cutting edge is fed into the cutting zone. In the present study, a longitudinal high-frequency vibration was superimposed to the rotary tool to analyze the cutting force and surface roughness of AA7075 during orthogonal cutting. However, due to contribution of wide ranges of factors in the vibratory-rotary turning process, the selection of optimal parameter setting is a challenge that is faced with this process. In the present work, an attempt was made to simultaneously minimize machining force ( Fz) and surface roughness ( Ra) through selection of the optimal setting of cutting velocity, feed rate, tool rotary speed in rotary turning, and vibratory-rotary turning operations. Here, grey relational analysis was used to find the optimal parameter setting in rotary turning and vibratory-rotary turning processes, separately. Then the obtained solutions were compared. Results indicated that applying axial vibration to the rotary tool turning significantly reduced both surface roughness and cutting force. From the optimization by the grey relational analysis method, it was obtained that for both rotary turning and vibratory-rotary turning operations, setting of 4 m/min cutting velocity, 220 r/min tool rotary speed, 0.08 mm/rev feed rate, and 0.3 mm depth of cut are the most-optimal solutions that causes minimum Fz and Ra, simultaneously. Also, the vibratory-rotary turning process had higher values of grey relational grade than the rotary turning process that implies outperformance of the vibratory-rotary turning with respect to the rotary turning process. The obtained results were then verified, compared, and discussed based on the mechanics of turning process.

Investigation of micro-injection molding based on longitudinal ultrasonic vibration core.

An ultrasound-assisted micro-injection molding method is proposed to improve the rheological behavior of the polymer melt radically, and a micro-injection molding system based on a longitudinal ultrasonic vibration core is developed and employed in the micro-injection molding process of Fresnel lenses. The verification experiments show that the filling mold area of the polymer melt is increased by 6.08% to 19.12%, and the symmetric deviation of the Fresnel lens is improved 15.62% on average. This method improved the filling performance and replication quality of the polymer melt in the injection molding process effectively.

Titanium wire drawing with longitudinal-torsional composite ultrasonic vibration

Compared with the conventional wire drawing process without ultrasonic vibration, which leads to high energy consumption and rough surface finish, the influences of longitudinal-torsional (L&T) composite ultrasonic vibration on titanium wire drawing process were investigated. The effects were discussed both numerically and experimentally in terms of friction force and stress, drawing force and stress, and processed wire surface quality. The analysis indicates that torsional ultrasonic vibration would increase the friction force in some extent, but only modestly, while longitudinal ultrasonic vibration is apparently beneficial to reducing the friction force in wire drawing process. Furthermore, both the longitudinal vibration and the L&T composite vibration are beneficial to decreasing the drawing force and improving the plastic deformation of titanium wires, especially for the latter. In addition, the longitudinal ultrasonic vibration could improve the surface quality of processed wires due to the friction force reduction. The L&T composite ultrasonic vibration could apparently reduce the drawing force as the result of its slight higher friction force within the contact area, which could provide the required plastic deformation energy at the cost of surface quality. The present research provides a new methodology for the ultrasonic titanium wire drawing process.

Investigation of the design method of an angled ultrasonic longitudinal solid horn

A solid horn is one of the key components of power ultrasonic longitudinal vibration system, and the most common horns are designed to allow the vibration travels along straight direction. However, some applications need to change the transmission direction of longitudinal vibration. The design method for angled ultrasonic longitudinal solid horns is investigated in this work. The frequency equation is established by using the continuity of displacement, force, bending moment and angle of rotation, as well as free boundary conditions at its two ends, and the method of calculation of displacement amplification factor is given. The resonant frequencies of some different fabricated angled solid horns consisted of two section bars are calculated by using the proposed frequency equation, and basically agree with the values by finite element method, and are validated by experiment with Vibpilot vibration test system. And then, connection these solid horns with a piezoelectric transducer with resonant frequency of 19.8 kHz, experimental comparison of the amplification factors and vibration modes of output port of the solid horns between the designed and fabricated angled horns validates the effectiveness of the design method. It shows that the longitudinal vibrations excited by transducer along the horizontal direction are successfully transferred to the output ports (in piston vibration) via the angled solid horns. Finally, the relationships between amplification factors of angled solid horns and their geometric dimensions are obtained through a lot of calculation.

A new piezoelectric ceramic longitudinal–torsional composite ultrasonic vibrator for wire drawing

This paper presents a new sandwich longitudinal–torsional (L&T) composite ultrasonic vibrator for wire drawing. The characteristic of this composite ultrasonic vibrator is driven by an axially poled piezoceramic stack, which is greatly different from the conventional composite ultrasonic vibrator driven by two or more piezoceramic stacks. Four uniform slanting grooves were cut off at the end part of the ultrasonic vibrator to transform the longitudinal ultrasonic vibration into an L&T composite motion. The effects of slanting grooves on the resonance frequency, amplitudes of longitudinal and torsional vibration were analyzed by the finite element method. Experiments were performed to verify the above simulation results. The experimental results met well with the theoretical results. It indicates that L&T composite ultrasonic vibration can be achieved by one piezoceramic stack, and applied in wire drawing. The present work provides a new methodology for ultrasonic wire drawing.

Improvement of ECAP process by imposing ultrasonic vibrations

In a few last decades, equal-channel angular pressing (ECAP) has been one of the most prominent procedures for fabrication of ultrafine-grained (UFG) structures among various severe plastic deformation (SPD) techniques. The objective of this paper is to experimentally investigate the influence of longitudinal ultrasonic vibrations on the ECAP process. A robust experimental ECAP system was designed and manufactured, in which the punch can be excited by ultrasonic vibrations. ECAP experiments were carried out with and without ultrasonic vibration on pure Al. The microstructure of the specimens formed with ultrasonic-assisted ECAP and conventional ECAP were studied. The results of this study showed that superimposing ultrasonic vibrations on the ECAP process could improve the grain refinement efficiency. The grains of the specimens after conventional ECAP process were refined to 45 μm, while by applying ultrasonic vibration with amplitudes of 2.5 and 5 μm, the grains were refined to 28.2 and 22 μm , respectively. Using higher vibration amplitudes caused more refinement of the grains. The homogeneity of the microstructure after four passes of ECAP was also improved by 26.7 % while using ultrasonic vibration with amplitude of 2.5 μm. Higher vibration amplitudes made a more homogenous structure. The yield strength and ultimate tensile strength of the specimens after one pass of ECAP were higher in comparison with the conventional ECAP.

The Dynamic Characteristic Analysis of Vibration System for Longitudinal and Torsional Ultrasonic Vibration Honing

The tool’s unique movement trajectory in longitudinal and torsional ultrasonic machining technology can help chip extraction. Cutting liquid can offer good lubrication, cleaning and cooling. It also can prolong tool’s life, improve the processing quality and processing efficiency, so it is widely used in precision and ultra-precision machining. It builds the model of ultrasonic vibration system, based on the motion analysis of longitudinal and torsional ultrasonic vibration honing. In addition, mode analysis, transient dynamic analysis and harmonic response analysis are carried out by means of finite element analysis software ANSYS. Using graphics and curve in the postprocessing module describe the results of numerical simulation. It can provide powerful model and theoretical basis for the structure design and performance optimization of ultrasonic vibration system, which is used for longitudinal and torsional ultrasonic vibration honing.

Investigation of ultrasonic-assisted wire electrical discharge turning based on single discharge analysis

In ultrasonic-assisted wire electrical discharge turning, the longitudinal ultrasonic vibration of the wire creates a longitudinal compressive and rarefaction wave front, which is successively aiding very violent and accelerative mass to transfer across the spark gap, acting as a pump, causing higher debris suspension and evacuation from the gap and higher dielectric fluid renewal. For this purpose, a specially designed and fabricated turning spindle is used. An auxiliary device which produced the ultrasonic vibration was installed between the two wire guides. The ultrasonic system consists of an ultrasonic generator, a transducer, and a wire holder. When the wire is being driven, the transducer and the wire holder are vibrated under the resonance condition. In this study, the size of eroded craters, surface roughness, recast layer thickness, and micro-crack, measured on the workpiece (anode) were found to be highly influenced by the applied ultrasonic vibration. It was found that the volume of the eroded craters increased by applying the ultrasonic vibration based on single discharge analysis. This means that the remaining lower melting material leads to the reduction of the recast layer thickness and micro-cracks. Based on the obtained results, in this process, the surface roughness is not changed under low discharge energy (finishing condition).

Theoretical and experimental analyses of ultrasonic-assisted indentation forming of tube

Indentation forming process is used for internal forming and sizing of thick-walled tubes working in high internal pressures. In this process, a mandrel with a diameter slightly larger than that of the tube is pressed and moved inside the tube, creating an internal profile. This article presents theoretically and experimentally influences of longitudinal ultrasonic vibration on this forming process. For this purpose, vibro-impact and continuous forming regimes have been investigated. Application of longitudinal ultrasonic vibration along the axis of the workpiece showed experimentally reduction of 15%–21% of axial forming forces and improvement of surface quality of the bore of the tube, while no effect on spring back of the formed zone was observed.