12/21/13 Ultrasonic horn - Wikipedia, the free encyclopedia

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Conventional Converging Ultrasonic Horn,

produced by Industrial Sonomechanics,

LLC[1]

Full-wave Barbell Ultrasonic Horn,

produced by Industrial Sonomechanics,

LLC[1]

Ultrasonic hornFrom Wikipedia, the free encyclopedia

An ultrasonic horn (also known as acoustic horn, sonotrode,acoustic waveguide, ultrasonic probe) is a tapering metal barcommonly used for augmenting the oscillation displacementamplitude provided by an ultrasonic transducer operating at the lowend of the ultrasonic frequency spectrum (commonly between 15and 100 kHz). The device is necessary because the amplitudesprovided by the transducers themselves are insufficient for most

practical applications of power ultrasound.[2] Another function ofthe ultrasonic horn is to efficiently transfer the acoustic energy from

the ultrasonic transducer into the treated media,[3] which may besolid (for example, in ultrasonic welding, ultrasonic cutting orultrasonic soldering) or liquid (for example, in ultrasonichomogenization, sonochemistry, milling, emulsification, spraying or

cell disruption).[1] Ultrasonic processing of liquids relies of intenseshear forces and extreme local conditions (temperatures up to 5000K and pressures up to 1000 atm) generated by acoustic

cavitation.[2]

The ultrasonic horn is commonly a solid metal rod with a roundtransverse cross-section and a variable-shape longitudinal cross-section - the rod horn. Another group includes the block horn,which has a large rectangular transverse cross-section and avariable-shape longitudinal cross-section, and more complex

composite horns.[4] The devices from this group are used with solidtreated media. The length of the device must be such that there ismechanical resonance at the desired ultrasonic frequency ofoperation – one or multiple half wavelengths of ultrasound in thehorn material, with sound speed dependence on the horn’s cross-section taken into account. In a common assembly, the ultrasonichorn is rigidly connected to the ultrasonic transducer using athreaded stud.

Ultrasonic horns may be classified by the following main features: 1) Longitudinal cross-section shape – stepped,exponential, conical, catenoidal, etc. 2) Transverse cross-section shape – round, rectangular, etc. 3) Number of

elements with different longitudinal cross-section profile – common and composite.[3][5] A composite ultrasonichorn has a transitional section with a certain longitudinal cross-section shape (non-cylindrical), positioned betweencylindrical sections.

Frequently, an ultrasonic horn has a transitional section with a longitudinal cross-section profile that convergestowards the output end. Thus, the horn’s longitudinal oscillation amplitude increases towards the output end, while

the area of its transverse cross-section decreases.[6] Ultrasonic horns of this type are used primarily as parts ofvarious ultrasonic instruments for ultrasonic welding, ultrasonic soldering, cutting, making surgical tools, moltenmetal treatment, etc. Converging ultrasonic horns are also commonly included in laboratory liquid processors used

12/21/13 Ultrasonic horn - Wikipedia, the free encyclopedia

en.wikipedia.org/wiki/Ultrasonic_horn 2/3

Longitudinal cross-sections of

simple half-wavelength

ultrasonic horns: 1 – conical, 2

– exponential or catenoidal, 3 -

stepped. In all figures: V(z) and

e(z) - distributions of amplitude

and deformation

Longitudinal cross-

section of a round

composite converging

half-wave ultrasonic

horn, where L1,L3 –

cylindrical sections, L2 –

catenoidal transitional

section

Longitudinal cross-section of a

round full-wave Barbell horn, where

L1, L2, L3 – cylindrical sections, L2

– exponential transitional section, L4

– conical transitional section

for a variety ofprocess studies,includingsonochemical,emulsification,dispersing and

many others.[7]

In high-powerindustrialultrasonic liquid

processors,[8]

such ascommercialsonochemicalreactors,ultrasonic homogenizers and ultrasonic milling systems intended for the treatment of large volumes of liquids at highultrasonic amplitudes (ultrasonic mixing, production of nanoemulsions, solid particle dispersing, ultrasonic

nanocrystallization, etc.), the preferred ultrasonic horn type is the Barbell horn.[7] Barbell horns are able to amplifyultrasonic amplitudes while retaining large output diameters and radiating areas. It is, therefore, possible to directlyreproduce laboratory optimization studies in a commercial production environment by switching from Converging toBarbell horns while maintaining high ultrasonic amplitudes. If correctly scaled up, the processes generate the same

reproducible results on the plant floor as they do in the laboratory.[7]

Maximum achievable ultrasonic amplitude depends, primarily, on the properties of the material from which anultrasonic horn is made as well as on the shape of its longitudinal cross-section. Commonly, the horns are madefrom titanium alloys, such as Ti6Al4V, stainless steel, such as 440C, and, sometimes, aluminum alloys or powderedmetals. The most common and simple to make transitional section shapes are conical and catenoidal.

Contents

1 Applications1.1 Plastics

2 References3 Further reading

Applications

Plastics

12/21/13 Ultrasonic horn - Wikipedia, the free encyclopedia

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Consumer products, automotive components, medical devices and most all industries utilize Ultrasonics. Metalinserts may be secured in plastic and dissimilar materials can often be bonded with proper tooling design. Ultrasonichorns come in a variety of shapes and designs, but all must be tuned to a specific operating frequency; the mostcommon being 15kHz, 20kHz, and 40kHz.

Ultrasonic welding utilizes high frequency, vertical motion to produce heat and the flow of thermoplastic material atthe interface of mated parts. Pressure is maintained after the delivery of energy is stopped to allow re-solidificationof interwoven plastic at the joint, securing the parts with a homogeneous or mechanical bond. This process offers an

environmentally friendly means of assembly as opposed to conventional adhesives or mechanical fasteners.[9]

References

1. ̂a b c Industrial Sonomechanics website, 2011 (http://sonomechanics.com)

2. ̂a b Peshkovsky, S.L. and Peshkovsky, A.S., "Shock-wave model of acoustic cavitation", Ultrason. Sonochem.,2008. 15: p. 618–628.

3. ̂a b Peshkovsky, S.L. and Peshkovsky, A.S., "Matching a transducer to water at cavitation: Acoustic horn designprinciples", Ultrason. Sonochem., 2007. 14: p. 314–322.

4. ^ Sonic Power website (http://www.sonic-power.com/ultrasonic_horn-horn-Ultrasonic_Sonotrode-Ultraschall_sonotroden-Ultraschallsonotrode-sonotrode-sonotroden-ultrasons_sonotrodes-Ultrasonic_Sonotroden)

5. ^ Abramov, O.V., "High-intensity ultrasonics: theory and industrial applications", 1999: CRC Press. 692.

6. ^ "Ultrasonic Horn Designs and Properties", Industrial Sonomechanics website, 2011(http://sonomechanics.com/technology/ultrasonic_horn_designs_and_properties)

7. ̂a b c "Barbell Horn Ultrasonic Technology", Industrial Sonomechanics website, 2011(http://sonomechanics.com/technology/barbell_horn_ultrasonic_technology/)

8. ^ "Ultrasonic Liquid Processor Systems", Industrial Sonomechanics website, 2011(http://sonomechanics.com/technology/ultrasonic_liquid_processor_systems/)

9. ^ "Ultrasonics", ToolTex.com, 2013 (http://tooltex.com/category/ultrasonics/)

Further reading

T. J. Mason, J. Phillip Lorimer (2002). Applied Sonochemistry: The Uses of Power Ultrasound inChemistry and Processing. Wiley-VCH. ISBN 3-527-30205-0.

Yatish T. Shah, A. B. Pandit, V. S. Moholkar (1999). Cavitation Reaction Engineering. Springer.ISBN 0-306-46141-2.

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Categories: Ultrasound

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