What's the Working Principle of Ultrasonic Impact Equipment ?

I. Working Principle of Ultrasonic Impact Equipment

超声冲击就是利用大功率的超声波推动冲击工具以每秒二万次以上的频率冲击金属物体表面，由于超声波的高频、高效和聚焦下的大能量，使金属表层产生较大的压塑性变形，同时超声冲击波改变了原有的应力场，产生一定数值的压应力，使超声冲击部位得以强化。超声波驱动电源通过电缆与设置在外壳内的超声波换能器连接，换能器的振动输出端部与变幅杆连接，变幅杆端部装有冲击针。超声波驱动电源将市电转换成高频高电压交流电流，输给超声波换能器，然后超声波换能器将输入的电能转换成机械能，即超声波。其表现形式是换能器在纵向作往复伸缩运动，伸缩运动的频率等同于驱动电源的交流电流频率，伸缩的位移量在十几微米左右。变幅杆的作用一是将换能器的输出振幅放大，达到100微米以上，另一方面对冲击针施加冲击力，推动冲击针高速前冲。冲击针冲击工件后，能量向焊缝传递，以达到消除内应力的作用。冲击头受工件的反作用后回弹，碰到高频振动的变幅杆后，再次受到激发，又一次高速度撞向焊缝，如此反复多次，完成冲击作业。

Ultrasonic impact is the use of high-power ultrasonic to drive impact tools to impact metal surface at a frequency of more than 20,000 times per second. Because of the high frequency, high efficiency and high energy of ultrasonic, the metal surface produces large compressive-plastic deformation. At the same time, the ultrasonic shock wave changes the original stress field and produces a certain number. The value of compressive stress strengthens the ultrasonic impact site. The ultrasonic driving power supply is connected with the ultrasonic transducer arranged in the housing through the cable, the vibration output terminal of the transducer is connected with the horn, and the end of the horn is equipped with an impact needle. Ultrasonic driving power converts municipal electricity into high frequency and high voltage AC current, which is transmitted to the ultrasonic transducer. Then the ultrasonic transducer converts the input electric energy into mechanical energy, that is, ultrasonic. Its form of expression is that the transducer makes reciprocating and retractable motion in the longitudinal direction. The frequency of retractable motion is equal to the AC current frequency of the driving power supply, and the displacement of retractable motion is about ten microns. The role of the horn is to amplify the output amplitude of the transducer to more than 100 microns. On the other hand, it exerts impact force on the impact needle to push the impact needle forward at high speed. After the impact needle impacts the workpiece, the energy is transferred to the weld to eliminate the internal stress. The impact head bounces back after the reaction of the workpiece, and is stimulated again after encountering the horn with high frequency vibration. It bumps into the weld seam at high speed again and again, thus completing the impact operation many times.

II. Principle and effect of improving fatigue life of ultrasonic impact equipment

超声冲击技术是一种高效消除部件表面或焊缝区有害残余拉应力，在工件表面形成压应力的方法，可以提高焊接件疲劳寿命和疲劳强度、高效、省时，推广超声波冲击技术符合国家可持续发展战略。焊后处理焊趾部位，降低余高造成的应力集中，消除焊趾表面的缺陷，同时使焊趾处产生较大的压缩塑性变形，产生一定数值的残余压缩应力，调整了焊接残余应力场，并使焊趾部位材料得以强化和硬化。大量实验数据表明超声冲击可使钢制焊接接头疲劳强度提高60-180%，寿命延长10-135倍，使铝、钛有色金属焊接接头疲劳强度提高了26-48%，寿命延长了5-45倍，有效改善了焊接接头及结构的疲劳性能。

Ultrasonic impact technology is an effective method to eliminate harmful residual tensile stress on the surface of parts or weld seam and to form compressive stress on the surface of workpiece. It can improve the fatigue life and fatigue strength of welded parts. It is efficient and time-saving. Promoting ultrasonic impact technology conforms to the national sustainable development strategy. After welding, the stress concentration caused by excess height is reduced, the defects on the surface of the weld toe are eliminated, and at the same time, a large compressive plastic deformation is produced at the weld toe, resulting in a certain amount of residual compressive stress, adjusting the welding residual stress field, and strengthening and hardening the materials at the weld toe. A large number of experimental data show that ultrasonic impact can increase the fatigue strength of steel welded joints by 60-180%, prolong their life by 10-135 times, increase the fatigue strength of aluminum and titanium non-ferrous metal welded joints by 26-48%, prolong their life by 5-45 times, and effectively improve the fatigue properties of welded joints and structures.

III. Areas of Application

超声波冲击技术在众多行业得以应用，其中包括：海洋、石油化工、船舶、重型起重机械及起重机、重型模具机械、风力涡轮机、钢或复合材料桥梁、航空和铁路等。

Ultrasonic impact technology has been applied in many industries, including ocean, petrochemical industry, ship, heavy lifting machinery and crane, heavy die machinery, wind turbine, steel or composite bridge, aviation and railway, etc.