The Dynamic Analysis And Design Of Horns Used In Ultrasonic Machining Based On Finite Element Method

With the development of science and technology, advanced engineering ceramics plays an increasingly important role in the modern manufacturing industries. Engineering ceramic materials have many attractive properties such as high hardness, high thermal resistance, corrosion resistance, chemical stability and low electrical conductivity, etc. The combination of these properties makes engineering ceramics suitable for a wide range of applications, such as in machinery, electronics, aerospace, automotive, and cutting tool industries. Ultrasonic machining is used extensively in the machining of high-performance composites, ceramics, quartz, graphite and semiconductor.The horn, an important component in ultrasonic machining equipment, has two functions. Firstly, it can amplify the displacement and amplitude of mechanical vibration and focus vibratory energy to a small area. Secondly, it can match the impedance between transducer and load in order to transmit ultrasonic energy efficiently. In this paper, we researched the performance of horns, which is based on enhancing the material removal rate in ultrasonic machining. The main contents are as follows:Firstly, using the theoretical formula, we designed the exponential, conical, stepped and composite horns respectively and obtained resonance length, displacement distribution and the amplification factor for each horn. The curve of displacement distribution can be obtained by the function of displacement distribution; it is accord with the performance of sinusoidal.Secondly, based on ANSYS7.0 (a kind of FEM software), finite element method is used to carry out the dynamic analysis of the exponential, conical, stepped and compositehorns respectively. The dynamic analysis mainly includes two aspects: mode analysis and harmonic response analysis. In mode analysis, natural frequencies of all horns are obtained within the range of excitation frequency. At the natural frequency, a sinusoidal vibration is applied in the input end of a horn, harmonic response analysis for each horn is conducted and the amplitude of the free end of the horn is obtained. Therefore, the amplification factor of the horn is calculated.Finally, we built a set of apparatus for experimental measurements. The measured horn is attached to the transmitting rod and two piezoelectric accelerometers are stuck to both ends of the horn. The power of ultrasonic generator is 250W. When ultrasonic vibration is transmitted from the transducer to the transmitting rod, then to the horn, accelerometers will measure the amplitudes of accelerations in both end of the horn. The charge amplifier is used to amplify the signals from the accelerometer. A digital oscilloscope is connected to the charge amplifier and records the data. Based on the values ofaccelerations, the amplitudes of displacement are easily computed. Therefore, we can obtain the amplification factor of the horn.It is discovered that the results from the finite element analysis is more consistent with that from experiments, compared with the results of theoretical solution. The primary investigation shows that dynamic analysis of horns using FEM will provide an effective method for designing the horns with complicated shape.