The Experimental Study Of Large Cross-section Composite Horn In Ultrasonic Shot Peening

At a predetermined period of time and under specified conditions, the mechanical parts that can’t finish the normal function, called failure. The failure forms of mechanical parts mainly include fracture, excessive residual strain, surface wear and corrosion, contact fatigue of the parts’ surface and resonance, etc. Shot peening technology is an important method to improve fatigue strength of the mechanical parts. In recent years, this method puts into use and promotes quickly in the aviation, shipbuilding, conventional weapons and other departments.Shot peening strengthening can not only improve the fatigue strength of the parts, but also improve the parts’ability of resisting stress corrosion. In addition to dramatically improving the mechanical properties above, the influence on the tensile strength (σb), yield strength (σs),impact strength (αk), plasticity (δ) and so on is no obvious. In addition, the cost of shot peening technology is low and its productivity is high.As a new kind of surface strengthening method, ultrasonic shot peening has more advantages than the traditional shot peening, it can get a deeper hardening layer and a large compressive stress, at the same time, its surface roughness is good. So, ultrasonic shot peening has potential application prospect.At present, the composite horn improves the shot speed obviously in the machining process of ultrasonic shot peening. The speed can meet the processing requirements, but now the output area of the composite horn becomes the main factor of constraining the efficiency. So, under the premise of existing a large amplitude, in order to increase the output area and improve the shot peening efficiency, this paper designs a large cross-section composite horn with analytic method. Then, all performance parameters of the horn are obtained through the dynamic analysis by using the large general finite element software ANSYS. In addition, according to the design parameters, in order to check the ability of ultrasonic shot peening strengthening, an experiment is performed. The main contents are as follows:1. Depth analysis of research, theory and design of the ultrasonic horn according to the actual requirements, to meet the large cross-section output and a larger amplification, a large cross-section composite horn is designed through choosing the area of the horn’s input and output section.2. Using the large general finite element software ANSYS to correct the design parameters and to simulate the final designed composite horn, obtain all performance parameters of the horn. Compared with the theory results, concluding that the designed composite horn is reasonable.3. According to the revised parameters, we manufacture the rectangular cross-section composite horn and measure its resonant frequency with PV70A impedance analyzer. For the limit of the experimental condition, this paper only discusses the composite horn’s amplification theoretically based on the theory. The designed horn can meet the requirements through comparing with the theoretical and simulation results.4. Choose different types of shot to perform the experiment. In the process of the ultrasonic shot peening, following the vibration of the tool, shots impact the piezoelectric sensor which is fixed in the screw, then the impact signal is amplified and transmitted to the oscilloscope which can display the peak voltage.5. Calculate the contact stress of the shot peening through the impact force which is obtained under different conditions. Analyze the results of the contact stress and obtain the parameters of shot peening technology how to influence the results.