一种圆弧过渡阶梯型超声变幅杆的节点法兰优化与参数型设计

Node flange optimization and parametric design of a circular arc transition stepped ultrasonic horn

超声波塑料焊接的纵振变幅杆需要易于装夹的无振动法兰,但薄片状法兰不易保证足够的刚度和加工质量,而厚片法兰易造成变幅杆的共振频率偏移,针对上述问题,对一种圆弧过渡阶梯型变幅杆进行了初步设计。在变幅杆的节点位置添加了薄片状法兰,然后对薄法兰的外侧加块,再利用ANSYS Workbench的Shape Optimization工具对块结构进行了优化,实现了在质量增加较少的情况下保证法兰处的强度;之后以两圆柱的长度为设计变量,对变幅杆进行了参数型设计,修正了变幅杆的长度,使其共振频率在19. 75 k Hz～20. 15 k Hz范围内,且节点恰好位于法兰处。研究结果表明:优化后的变幅杆振型呈轴向阶梯型分布,法兰无振动且易于装夹,薄片状法兰式变幅杆质量为0. 85 kg;优化后的变幅杆质量为0. 914 kg,质量增长了7. 5%,等效应力减少了21. 4%,最大主应力减少了59. 6%。

Aiming at the problems that the flange of longitudinal vibrating horn for ultrasonic plastic welding was needed to be easy-clamping and with no vibration,the rigidity and machining quality of the thin plate flange was not easily guaranteed,and the frequency of horn was easily shift with a thick plate flange,a circular arc transition step transformer was preliminarily designed and added a thin plate flange to the node location.Then a block was added on the outside of the thin flange with ANSYS Workbench Shape Optimization tool for optimization to guarantee the flange strength with less weight added.Then the parametric design of the horn was made for fixing horn length to make the resonance frequency around 19.75kHz -20.15kHz and to locate the node in the flange with the two-cylinders'length as design variables.The results indicates that the vibration profile of the optimized horn is axial stepped distribution,and there is no vibration in the flange and it could be easily clamped at the flange .The mass of the thin flanged horn is 0.85kg.The optimized horn is 0.914kg,the mass is increased by 7.5%,the equivalent stress is reduced by 21.4%,the maximum principal stress is reduced by 59.6%.