具有夹角结构纵振动变幅杆的设计方法

Investigation of the design method of an angled ultrasonic longitudinal solid horn

变幅杆是功率超声纵振系统中的关键部件之一,常见的是沿直线方向传播的变幅杆.有的应用场合需要变换纵振动传输方向.本文研究了具有夹角结构的超声纵振动变幅杆的设计方法.利用两端自由边界条件和夹角连接处的位移、力、弯矩及转角连续条件建立了设计变幅杆的频率方程,给出了计算变幅杆振幅放大系数的方法.利用本文中提出的设计方法,计算了若干个由两段杆组成的不同夹角的变幅杆的谐振频率,与有限元计算结果及Vib Pilot系统测试的变幅杆频率基本一致;后与谐振频率为19.8k Hz的压电换能器相连接,激光测振仪测试了系统的谐振频率、变幅杆的放大系数及变幅杆输出端面的振型.测试得到的变幅杆的放大倍数、振型与计算结果吻合.测试的端面振型呈活塞振动,说明在谐振频率上将换能器激励的沿水平方向的纵向振动,经过变幅杆成功地变换到了其输出端上.最后,对该型变幅杆作了大量计算,得出了放大倍数随几何尺寸变化的规律.

A solid horn is one of the key components of power ultrasonic longitudinal vibration system, and the most common horns are designed to allow the vibration travels along straight direction. However, some applications need to change the transmission direction of longitudinal vibration. The design method for angled ultrasonic longitudinal solid horns is investigated in this work. The frequency equation is established by using the continuity of displacement, force, bending moment and angle of rotation, as well as free boundary conditions at its two ends, and the method of calculation of displacement amplification factor is given. The resonant frequencies of some different fabricated angled solid horns consisted of two section bars are calculated by using the proposed frequency equation, and basically agree with the values by finite element method, and are validated by experiment with Vibpilot vibration test system. And then, connection these solid horns with a piezoelectric transducer with resonant frequency of 19.8 kHz, experimental comparison of the amplification factors and vibration modes of output port of the solid horns between the designed and fabricated angled horns validates the effectiveness of the design method. It shows that the longitudinal vibrations excited by transducer along the horizontal direction are successfully transferred to the output ports （in piston vibration） via the angled solid horns. Finally, the relationships between amplification factors of angled solid horns and their geometric dimensions are obtained through a lot of calculation.