Research On The Hole Type Large Amplitude Horn

In recent years,with the widespread application of ultrasonic technology in various fields,people have paid more and more attention to ultrasonic processing and ultrasonic processing.Ultrasonic machining can solve some technical problems encountered in traditional machining methods,improve the quality of processed work piece,and enhance the processing efficiency.Ultrasonic processing is also widely used in ultrasonic sewage treatment,ultrasonic emulsification,ultrasonic dispersion and other aspects.The ultrasonic vibration system is indispensable for ultrasonic processing,and generally consists of an ultrasonic transducer,an ultrasonic horn,and a processing tool head.First,the ultrasonic generator sends out an electrical signal,which is converted into a mechanical wave by an ultrasonic transducer,and then the amplitude is amplified by an ultrasonic horn and transmitted to the processing tool head.The main role of the ultrasonic horn in the vibration system is to collect ultrasonic vibration energy on a small area at the output end,amplify the mass displacement or velocity of the mechanical vibration,and also serve as a mechanical impedance converter in the transducer and sound load to impedance matching.In practical application,the ultrasonic horn needs to be designed according to different application requirements,so as to improve and improve the efficiency of ultrasonic processing and processing,and extend the service life of the transducer.In practical applications,in order to meet different processing requirements and obtain large vibration energy,it is necessary to design horns of various shapes.When processing fragile materials such as ceramics,traditional methods such as lasers and water jets are often used,but the equipment is more complex and large,which often takes time and effort.The size of the output end of the horn is generally smaller than the size of the input end,thereby amplifying the amplitude of the ultrasonic wave and achieving the energy concentration.However,in some applications of ultrasonic treatment(such as ultrasonic dust removal,ultrasonic treatment of domestic wastewater and ultrasonic condensation,etc.),high-power,large-area ultrasonic radiation is required,so that the processing range is large and the efficiency is high.At this time,it is hoped that the horn has a large output area,good amplification factor and stability,but the amplification factor of the small-end input large-end output horn is often less than 1.Aiming at the above problems,the theoretical design and finite element software simulation calculation of the horn model was established,and the amplification factor of the horn was optimized as an objective function to obtain the optimal opening size of the horn with a large amplification factor..Finally,the stress optimization of the horn was carried out.The specific work is as follows:(1)In order to more efficiently perform ultrasonic-assisted drilling of fragile materials such as ceramics,a cylindrical horn with a cylindrical center hole is proposed.The radius of the hole is consistent with the outer diameter of the horn.Based on the analytical method,the frequency equation and performance parameter expressions of the horn are derived.The goal is to obtain a horn with a large magnification factor,and the structure is optimized by changing the length of the horn with a hole and the radius of the center hole.The results show that under the premise that the cross-section ratio of the input and output ends of the horn with a hole does not exceed 4.6(that is,the center hole radius does not exceed 88%of the outer diameter),when the resonance frequency and the center hole radius are constant,the resonance length and displacement node position As the length of the solid portion increases,it decreases first,then increases and then decreases,and the amplification factor increases first and then decreases as the length of the solid portion increases.When the length of the solid part of the horn is half of the resonance length,the amplification factor increases with the radius of the cylindrical hole increases.(2)A cylindrical ultrasonic rod with a conical center hole is proposed.Based on the wave equation of the one-dimensional longitudinally vibrating variable-section rod,the frequency equations and performance parameter expressions of these two types of hole horns are deduced by analytical methods,and the influence of different parameters on the performance parameters and their relationship are analyzed.The finite element method calculates the distribution of stress and vibration displacement along the axial direction of these two horns in the resonance state.The results show that the amplification factor of the horn with a hole is larger than that of a solid cylindrical horn at the same resonance frequency and area factor;the amplification factor of a horn with a tapered hole is smaller than that of a cylindrical horn but the stress curve is smooth and the stress maximum is small.(3)In some ultrasonic processing applications,in order to make the processing range large and efficient,it is desirable that the horn has a large output area,but the amplification factor of the small-end input large-output surface horn is often less than 1.In order to meet the requirements of amplitude amplification factor and stress in actual processing,an inverted tapered horn with a transverse rectangular through hole at the front end was proposed based on a solid inverted tapered rod.The finite element method calculates the displacement of the output end face at the resonance frequency.It can be seen that the vibration form of the output end face of the horn changes from plane vibration to bending vibration.The displacement distribution law of the output end face and the average amplification factor were calculated.The amplification factor was larger than the solid horn of the same size.The effects of the geometry of hole on the rod amplification factor and resonance frequency were studied.In order to obtain a larger magnification factor,the average magnification factor of the horn is further optimized as an objective function,and the optimal opening size of the large magnification factor horn is obtained.Considering the problem of stress concentration at the right angle of the rectangular hole,the four right angles of the optimized horn were changed to arc angles,which reduced(transverse),avoided(vertical)stress concentration,and increased the average amplification factor.The inverted tapered transverse through-hole horn is further optimized,which has certain guiding significance for the design and research of horns with holes.