换能器结构参数对聚合物超声塑化黏弹生热的影响

为研究超声换能器结构参数对聚合物超声塑化过程黏弹性生热的影响，首先确定超声黏弹性生热系统的组成，进行纵振超声换能器结构设计；然后分析超声黏弹性生热过程及超声黏弹性生热原理；最后采用单一变量法分析超声换能器的主要结构参数对其纵振频率及工具头前端质点最大振幅的影响，将其实际输出的纵振激励加载于熔融聚合物，研究其结构参数对聚合物超声黏弹性生热过程及达到聚合物玻璃化转变温度所用时间的影响。结果表明，随纵振激励作用时间的增加，聚合物温度非线性升高；放大比对聚合物温度变化影响最大，前盖板厚度和工具头长度次之，影响最小的是变幅杆长度。

Influence of Structural Parameters of Ultrasonic Transducer on Viscoelastic Heat Generation of Polymer

In order to study the influence of structural parameters of longitudinal vibration ultrasonic transducer on the viscoelastic heat generation of polymers during the ultrasonic plasticization process,the composition of ultrasonic viscoelastic heat generation system was determined,and then the structure of longitudinal vibration ultrasonic transducer was designed. The ultrasonic viscoelastic heat generation process and the corresponding mechanisms were analyzed. A single variable method was adopted to investigate the influence of structural parameters of the transducer on the longitudinal vibration frequency and maximum amplitude of the particle at the front end of tool head. Finally,the longitudinal vibration excitation of the transducer was loaded on the molten polymers to study the effect of structural parameters on the ultrasonic viscoelastic heating process of the polymer and the time required for reaching its glass transition temperature. The results indicated that the polymer temperature increases nonlinearly with an increase of longitudinal vibration excitation time. The amplification ratio generated the much greater influence on the variation of polymer temperature than on the front cover thickness and tool head length,but there was the least influence on the horn length.