【作者】 徐阳；

【导师】 于红英；

【作者基本信息】 哈尔滨工业大学 ， 机械工程， 2023， 硕士

【摘要】 超声波金属焊接在静压力加载下通过高频机械振动为焊材传输摩擦功以及形变能,是一种不通过焊材熔化就可实现固态焊接的新兴工艺技术。超声波金属点焊对待焊件外表面要求低,焊接成品电阻系数极低,具有熔合强度高、焊接效率高、焊接过程清洁环保等诸多优势。本文在超声波金属焊接工作特性分析的基础上,设计了以气动元件作为加载机构的点焊机机械本体,设计了超声波驱动电源以及驱动控制程序,利用本设备进行试验并完成了金属焊片的焊接。首先,分析了点焊机焊接组件对待焊片的作用机理,根据压电材料纵向振动的条件,建立了超声波声组件这一机电耦合系统的等效电路模型。在等效电路模型的基础上,研究了声组件阻抗和相角随频率变化的特性,推导出了压电换能器的谐振频率公式。在阻抗特性分析的基础上,确定了为声组件并联电感的匹配方式,并完成了调谐匹配部分电路的设计。其次,确定了气动加载式超声波金属点焊机的功能要求,设计了点焊机的总体方案。在机械系统的设计中规划了点焊机执行机构的总体布局,使用COMSOL多物理场仿真软件进行了声组件的模态分析,并以分析结果为基础设计了声组件的装夹机构。完成了焊接压力加载机构和待焊件压紧机构的结构设计以及元器件选型,最终进行了点焊机机械主体的装配。再次,基于压电材料的逆压电效应和点焊机功能要求,设计了超声波驱动电源的总体方案,整个驱动电源分为使用强电的调压驱动板和使用弱电的采样控制板。完成了频率控制模块、信号采集模块、最小系统模块、整流模块、直流逆变模块和调压匹配模块的设计,进行了电路板的制作以及调试。设计了点焊机驱动控制程序,控制程序包括频率扫描程序和恒振幅控制程序。最后开展了超声波金属点焊机性能测试,通过对驱动电源各模块的测试验证了驱动电源硬件功能的完整性和工作的有效性。开展了振幅控制试验,验证了驱动电源对声组件工具头端面振幅的控制能力,并提供适当的变负载环境验证恒振幅控制的可行性。使用驱动压力加载机构对工具头进行了不同程度的加载,探究了声组件在径向压力负载条件下阻抗特性的变化规律。完成了点焊机焊接试验,通过对紫铜焊片和纯铝焊片的焊接验证了点焊机的焊接能力。更多还原

【Abstract】 Ultrasonic metal welding,under static pressure loading,transmits friction work and deformation energy to the welding material through high-frequency mechanical vibration.It is an emerging processing technology that can achieve solid-state welding without melting the welding material.Ultrasonic metal spot welding has low requirements for the outer surface of the welded part,extremely low resistance coefficient of the welded product,and many advantages such as high fusion strength,high welding efficiency,clean and environmentally friendly welding process.Based on the analysis of the working characteristics of ultrasonic metal welding,this article designs the mechanical body of the spot welding machine with pneumatic components as the loading mechanism,designs the ultrasonic driving power supply and driving control program,after all uses this equipment to achieve the welding of copper and pure aluminum welding pads.Firstly,this article analyzes the mechanism of the action of the spot welding machine on the welding pad.Based on the conditions of longitudinal vibration of piezoelectric materials,the equivalent circuit model of the piezoelectric transducer,an electromechanical coupling system,has been established.On the basis of the equivalent circuit model,this paper studies the characteristics of the impedance and phase angle of the acoustic component changing with frequency,and calculates the resonant frequency formula of the piezoelectric transducer.Based on the analysis of impedance characteristics,the matching method for parallel inductance of acoustic components was determined,and the design of the tuning matching circuit was completed.Secondly,this article determines the functional requirements of the pneumatic loaded ultrasonic metal spot welding machine,and based on this,designs the overall scheme of the spot welding machine.This article plans the overall layout of the execution mechanism of the spot welding machine in the design of the mechanical system,and uses COMSOL multi-physical field simulation software to conduct modal analysis of the acoustic components used.Based on the analysis results,the clamping mechanism of the acoustic components is designed.This article has completed the structural design of the welding pressure loading mechanism and the pressing mechanism of the parts to be welded,and selected the components.Finally,complete the overall assembly work of the mechanical body of the spot welding machine.Afterwards,this article designs the overall design scheme of the ultrasonic driving power supply based on the principle of piezoelectric material driving and the functional requirements of the spot welding machine.The entire driving power supply includes a voltage regulating drive board using strong current and a sampling control board using weak current.In this article,the design of the drive signal frequency control module,signal acquisition module,minimum system module,rectification module,inverter drive module,and voltage regulation matching module has been completed,and the production and debugging of the circuit board have been completed.In this article,I also designed a spot welding machine driver control program,which includes a frequency scanning program and a constant amplitude control program.Finally,this article conducted performance tests on ultrasonic metal spot welding machines.This article verifies the integrity of the hardware functionality and effectiveness of the driver power supply through testing of each module.In this article,I conducted amplitude control experiments to verify the control ability of the driving power supply on the amplitude of the acoustic component tool head end face,and provided an appropriate variable load environment to verify the feasibility of constant amplitude control.Afterwards,a cylinder was used to load the tool head to varying degrees to investigate the impedance characteristics of the acoustic component under radial pressure loading conditions.In addition,this article also introduces the results of the welding test of the spot welding machine,and verifies the welding ability of the spot welding machine through the welding of red copper welding pads and pure aluminum welding pads.更多还原