压焊

20095112超声焊接压电换能器的研制／齐海群…／／焊接学报．-2009,30（6）：17-20 基于变截面杆作一维纵向振动运动方程,在理论分析的基础上,根据四端网络传递方程和端面运动状态,推导出了常用截面形状细杆在各种运动状态下,边界条件和四端网络传递矩阵参数以及频率方程。研究了适用于超声焊接的压电换能器的设计方法。     

压焊

20095112超声焊接压电换能器的研制／齐海群…／／焊接学报．-2009,30（6）：17-20 基于变截面杆作一维纵向振动运动方程,在理论分析的基础上,根据四端网络传递方程和端面运动状态,推导出了常用截面形状细杆在各种运动状态下,边界条件和四端网络传递矩阵参数以及频率方程。研究了适用于超声焊接的压电换能器的设计方法。     

超声振动辅助微塑性成形系统设计与开发

针对微塑性成形工艺过程对位移、力等参数精确控制的要求,分析了超声振动辅助成形系统的设计要点,提出了关键设计参数。超声振动辅助微塑性成形系统由机床本体系统、超声振动系统和伺服控制系统等主要单元组成。机床本体设计参考四柱液压机结构形式,采用两端固支梁和压杆的简化模型,计算得到主要结构尺寸,并用ABAQUS验证其刚度。通过选用匹配的超声发生器和换能器,满足成形过程中的超声振动要求,利用理想变截面杆纵振波动方程设计变幅杆结构,并用ABAQUS进行变幅杆模态分析,确保设计振幅满足要求。伺服控制系统采用可编程多轴控制器PMAC卡控制伺服电机,通过光栅尺和力传感器反馈实现高精度的位置及成形压力控制。通过测试证明在纯铜压缩试验中叠加超声振动,成形压力显著降低,成形精度达到4μm。     

热超声键合压电换能器的动力学特性

基于有限元方法和试验测试,研究了芯片封装用压电超声换能器的动力学特忡。借助ANSYS压电耦合和非线性接触分析功能,对换能器自由和约束状态下的振动特性进行了分析。探讨了超声能量在空间域、时域和频域的传递规律。由模态分析得到换能器的振动形式,通过谐响应分析提取其在正弦电压激励下的振动信息,经瞬态分析获得换能器的瞬态响应。结果表明,螺栓径向尺寸和预紧力影响换能器的模态分布和动态特性,压电晶堆加载电压的频率影响超声能量传递特性。通过键合试验考察了焊点质量与螺栓径向尺寸的关系。分析和试验结果为换能器设计和键合工艺优化提供了指导。     

基于UG平台的压电超声振动CAD系统开发

以UG为开发平台，利用UG的二次开发工具开发出了压电超声振动CAD系统。着重介绍了换能器和变幅杆两个关键模块的算法思想和实现方法，最后给出了利用该系统设计的实例。     

基于超声搅拌摩擦焊的变幅杆设计与仿真研究

超声搅拌摩擦焊接装置有助于解决搅拌摩擦焊技术在厚板焊接上的难题,变幅杆能将换能器输出端只有几个μm的超声振动放大至实际需要的几十至几百μm数量级,并带动搅棒针作超声波振动.为满足不同形状变幅杆的设计,导出了变截面变幅杆的振速分布函数和应力分布函数,设计了超声搅拌摩擦焊变副杆,并利用MATLAB进行了数值仿真计算,仿真结果表明:在变幅杆输出端(X=160 mm)附近,振动速度达到最大值,整个超声系统的前后端振速比约为10倍,满足实际应用的要求.     

超声加工振动系统设计的若干问题

本文讨论应用于超声加工的压电换能器的设计问题,简介几种常用的超声变幅杆,并提出两种新型变幅杆的设计方法。一、引言超声加工是功率超声应用中比较早用于生产的技术之一,国内外已有广泛的应用。超声加工设备中的关键部件是超声换能器及变幅杆(包括传振杆),加上加工工具一般统称为超声振动系统(见图1),其主要作用是把电能转换为声能并依特定要求传送到加工区域。     

抗性负载的余弦形复合变幅杆设计及动力学特性研究

为了解决简单形状变幅杆有时无法满足实际工程应用需要的问题,运用变幅杆纵向振动等效四端网络的方法,推导出质量抗性负载的余弦形复合变幅杆频率方程和放大系数一般公式;同时讨论负载变化对变幅杆性能的影响.依据理论通式设计了一个变幅杆,应用有限元软件ANSYS对其进行模态分析和谐响应分析,结果表明:其共振频率和放大系数与设计理论值吻合较好,从而验证了设计的合理性,为超声复合变幅杆和工具的设计和应用提供了一定的理论依据.     

一种用于精密振动切削的超声振子的设计与实验研究

精密超声振动切削是一种特种加工方法,对这种切削加工方法的研究工作在国内正处于快速发展阶段,为了能解决其中振动产生的问题并实现精密加工的要求,研制了用于精密数控车床上的超声振子,其中换能器采用压电夹心式结构,变幅杆采用复合式结构,其功能是产生满足切削加工要求的超声振动,并通过仿真与实验的方法验证了设计的变幅杆的性能满足切削加工的要求.最后,进行了精密切削实验,并进行了加入超声振动后与不加振动的车削工件表面粗糙度值的研究,得出超声车削出的工件表面质量优于普通车削.     

超声-电弧复合焊接系统换能器优化设计

研究了超声-电弧复合焊接系统中超声换能器的优化设计方法.根据超声-电弧复合焊接系统工作条件确定了超声换能器整体形式和各部分材料.通过传统解析法推导了超声换能器整体谐振频率方程,求解各部分基础尺寸.利用有限元分析软件ANSYS对解析法设计的超声换能器结构进行了模态分析,研究了前后盖板尺寸对于超声换能器谐振频率的影响并优化...     

径向振动匹配层换能器的设计参数及模态优化

设计基于匹配层外壳的径向振动换能器,分析匹配层材料、换能器直径、压电振子厚度对换能器模态振型的影响,并结合设计频率下最佳模态振型优化换能器设计参数。结果表明:树脂基匹配层显著提高换能器在空气介质中的发射效率。随着换能器直径减小、压电振子厚度增加,径向振动换能器激振效率提高。优化的换能器直径为100 mm,压电振子厚度为10 mm,在第三阶谐振频率为34 729 Hz时,可实现高效率、高质量振动辅助研磨加工。      

Shear horizontal piezoelectric fiber patch transducers (SH-PFP) for guided elastic wave applications

A new type of a lightweight piezoelectric transducer is proposed for selective excitation of horizontal polarized shear (SH) waves. Based on piezoelectric fibers the transducers are flexible, i.e. show structure conformity. The novel approach allows to introduce significant surface tractions by a transducer with double layer crossed fiber arrangement without the need of heavy seismic masses. The transducer operating principles are explained and the performance of a first transducer version is demonstrated by laser vibrometric measuring of the waves emitted into a plate. Numerical modeling of the identical arrangement shows nearly perfect agreement with measurements for the main features while differences in some details helps to understand how the first transducer version can be improved. The transducer exhibits, depending on its aspect ratio, a rather high directivity and a strong mode selectivity.     

A new method and instrument for measuring circular motion error of NC machine tools

A new method and instrument for measuring circular motion error of numerical control (NC) machine tools are described in this paper. The instrument consists of a linear displacement transducer bar with two balls at each end and a high accuracy rotary encoder. The radius variations are detected by the transducer and the rotation angle of the bar is measured by the rotary encoder while the machine is moving in a circular path. The measuring area is circular except for a small area around the center of the disc. The bar can be expanded and contracted along its axis for different application. The instrument has a compact structure and can be installed on a machine tool simply and quickly. It is shown by the experimental results that the instrument has good repeatability and high precision of measuring circular motion trajectories. The instrument can be widely used especially in the error-compensation and error-source project in the industrial application.     

Printing of uniform PZT thin films for MEMS applications

A flexible manufacturing method for the deposition of lead zirconate titanate (PZT) thin films based on ink jet printing has been developed and used to fabricate a first functioning piezoelectric micromachined transducer by printing. The performance of the printed PZT based transducer was fit to established models to determine piezoelectric coupling and dielectric properties. The piezoelectric coefficient, d₃₁, for printed PZT was between −75 pC/N and −95 pC/N. The relative permittivity was 750–890 and the dielectric loss tangent was 2.4–2.8%. This process enables digital deposition of printed devices with the key properties within the range required for high performance piezoelectric MEMS.     

带条码录入功能的网络变频冰箱控制器的研究

对一种新型带条码录入功能的网络变频冰箱控制器进行了研究。并着重对系统的组成，网络冰箱与家庭网络中央控制器无线网络接口的硬件电路设计，条码录入技术，直流无刷电机的变频调速原理及其具体硬件电路和软件设计进行了详细的阐述。     

A new technique for measuring the acoustic nonlinearity of materials using Rayleigh waves

This note presents a procedure to generate nonlinear Rayleigh surface waves without having to drive the transmitting piezoelectric transducer at high voltages; driving at low voltages limits the excitation of the intrinsic nonlinearity of the piezoelectric transducer element, and enables an efficient measurement procedure to isolate inherent material nonlinearity. The capabilities of this proposed technique are demonstrated by measuring the material nonlinearity of aluminum alloy 2024 and 6061 plates with Rayleigh surface waves.     

高α值加速度传感器标定方法的理论探讨与分析

从理论上探讨了标定高α值加速度传感器的方法,用一端受轴向冲击的等截面均匀细杆产生的应力波作为标定加速度传感器的冲击脉冲,由理论推导出自由杆的一端加速度和杆上的应变关系。在杆的这一端安装加速度传感器,就可对传感器进行标定。     

Designing and evaluating transducers for narrowband ultrasonic spectroscopy

Introduction of new composite materials in aerospace applications has created a demand for an efficient NDE technique. Ultrasonic resonance inspection is especially suitable for the inspection of multilayered structures. In our previous work we have described the principle of narrowband ultrasonic spectroscopy (NBUS), where the surface of an inspected structure is scanned with a resonant transducer whose frequency response is monitored in a narrow frequency band. This paper is concerned with optimizing the NBUS setup consisting of a piezoelectric transducer coupled to a multi-layered structure. Differences in the electrical impedance of a piezoelectric transducer caused by variations of parameters of the inspected structure are estimated using an equivalent circuit model and a finite element analysis. The theoretical analysis presented in the paper results in design guidelines for NBUS transducers.