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A n ultrasonic compound horn is designed and manufactured, and the horn is analyzed by wave equation, finite element method and test. The modal frequencies and frequencies of the first and second longitudinal vibration of the horn are obtained by the finite element analysis. The horn is made and modal testing is carried out. The modal frequencies of the first and second longitudinal vibration are obtained respectively. The test results are in good agreement with the theoretical calculation. Experimental results show the maximum amplitude of the horn can reach 9 nm with applied excitation voltage of amplitude 7 V and frequency 21,450 Hz, when the amplitude of voltage increases to 80 V, the horn of maximum amplitude reaches 23 μm. The maximum amplitude of the horn is approximately proportional to the amplitude of excitation voltage. The horn has the characteristics of high sensitivity and large amplitude, and can be used in ultrasonic machining and other fields.

Ultrasonic horn is very important in high power ultrasound equipment in the vibration system, the main function is to amplify the displacement and velocity of mechanical vibration particle, or concentrate the ultrasonic energy on a small area [

The structure of the ultrasonic horn was shown in

The piezoelectric ceramic plate is made of a plurality of ceramic pieces. Layout of ceramic plate adopts homopolarly opposite placed, and ensure elongation and contraction of ceramic plates. When the applied electric field direction is in accordance with the polarization direction of the ceramic plate, according to the piezoelectric vibration mode, the ceramic plate produces an elongation deformation, and conversely the ceramic sheet shrinks.

The shape of the cone and stepped cylinder can amplify the amplitude.

The ultrasonic horn is to enlarge the particle displacement or velocity of mechanical vibration, and its performance parameters include resonance frequency, amplification coefficient and so on. The amplification factor is the ratio of the particle displacement or velocity amplitude between the output and the input at the resonant frequency of the ultrasonic horn. The working principle of the ultrasonic is explained by a stepped shape which is shown in

The symmetrical axis of the horn is shown in

In the formula,

When the horn has no load, that is,

node can be obtained

The amplitude ratio of the top and the end of the horn is the magnification factor which can be represented as:

By the formula (3), displacement node has something to do with influence factors including the length of big end and small end of the stepped ultrasonic horn, the material and so on.

By the formula (4), the amplitude ratio at the top and end of the horn has something to do with influence factors including the diameter of big end and small end of the stepped ultrasonic horn, circular wave number and so on.

The finite element model of the ultrasonic horn shown in

Modal analysis is carried out for the finite element model of the ultrasonic horn shown in

The frequency of the second longitudinal vibration of the ultrasonic horn is 20,350 Hz, and the mode of vibration is shown in

Parameters | Values |
---|---|

Dielectric constant matrix | |

Piezoelectric constant matrix | |

Stiffness matrix |

According to the theoretical analysis, the ultrasonic horn was made. The object was shown in

Modal testing of the ultrasonic horn was performed by using PSV-500 Doppler scanning laser vibrometer. The section of small end of the ultrasonic horn was swept by the laser vibrometer, and the sweep frequency range was 0 - 25 khz. The excitation voltage increases from zero, and when 7 V is reached, the response diagram of the ultrasonic horn within the 0 - 25 khz frequency range can be measured and shown in

As could be seen from

When the excitation voltage amplitude was 7 V, the vibration of the end surface could be measured axially at two frequencies of 17,248 Hz and 21,646 Hz respectively. When the excitation frequency was 21,646 Hz, the displacement response of the ultrasonic horn was shown in

In order to determine the axial mode shapes of the ultrasonic horn, the horn was tilted and the exciting signal was applied under the same conditions. When the excitation signal voltage was 7 V and the frequency was 17,248 Hz, the frequency sweep was carried out along the axial direction of the ultrasonic horn, and the modal shape of the ultrasonic horn could be measured as shown in

When the excitation signal voltage was 7 V and the frequency was 21,646 khz, the frequency sweep was carried out along the axial direction of the ultrasonic

horn, and the modal shape of the ultrasonic horn could be measured as shown in

When the frequency of the excitation signal was set as 21,646 khz, and the voltages were set to 20 V, 40 V, 60 V and 80 V respectively, the maximum amplitude of the horn varied with the amplitude of the voltage, as shown in

When the excitation frequency is 21,646 khz, the amplitude is 80 V, the maximum amplitude of the ultrasonic horn could reach 23 µm. The ultrasonic horn could be used in ultrasonic machining and other fields

An ultrasonic horn is designed, and the finite element analysis and modal experiment are carried out. The maximum amplitude of the horn can reach 9 nm with applied excitation voltage of amplitude 7 V and frequency 21,450 Hz, when the amplitude of voltage increases to 80 V, the horn of maximum amplitude reaches 23 µm. The maximum amplitude of the horn is approximately proportional to the amplitude of excitation voltage. The horn has the characteristics of high sensitivity and large amplitude, and can be used in ultrasonic machining and other fields.

This work was financially supported by the National Natural Science Foundation of China (No.50865181) and Qinlan Project.

Wang, H.B. and Sun, C.H. (2017) Finite Element Analysis and Test of an Ultrasonic Compound Horn. World Journal of Engineering and Technology, 5, 351-357. https://doi.org/10.4236/wjet.2017.53029