【作者】 汤迪铭；

【导师】 洪波；

【作者基本信息】 湘潭大学 ， 材料加工工程， 2011， 硕士

【摘要】 随着焊接成形技术对机械制造业各个领域的渗透,发展和应用新型焊接自动化技术将对国民经济起到巨大的作用,而焊缝跟踪技术正是焊接自动化研究的一个重要方面。针对工程常用的窄间隙I型对接坡口焊缝缺乏稳定有效的跟踪方法这一难题,结合交变磁场测量(ACFM)技术在无损检测领域的成熟应用,设计开发了一种基于ACFM原理的新型电磁传感器应用于焊缝跟踪。本文通过传感器的空间磁场建模,重点研究由工件焊缝引起的磁场畸变信号与焊缝位置之间的内在联系;并根据磁场信号低信噪比的特点以及焊接环境要求设计信号处理电路精确提取所需信号,同时对部分电路进行仿真优化。具体研究内容如下:(1)对交变磁场焊缝跟踪传感器的基础理论和可行性进行研究。分析了ACFM技术的基本原理和工作过程,在此基础上建立了空间磁场简化数学模型,完成了三维空间各个方向磁感应强度理论计算;研究了沿焊缝长度方向同一水平面上各点的磁场分布规律,以完成对焊缝起止点位置信息的获取;研究了垂直焊缝方向一定区域内的磁场分布规律,以完成对焊缝左右偏差方向和幅度信息的获取,并采用数值分析方法对分布曲线进行拟合,确定磁场强度和焊缝位置信息两者之间的近似函数关系;最终设计了焊缝跟踪传感器采集磁场畸变信号的工作流程图。(2)设计了以前置差分放大、50Hz工频陷波、高阶无漂移低通滤波为主的信号处理电路,并对其进行MATLAB仿真分析;鉴于模拟陷波器无法滤除残留工频谐波噪声,设计了阻带选择性高和信号失真度小的整系数多阻带带阻数字滤波器;针对复杂恶劣的焊接环境和跟踪系统的实时性对滤波器稳定性和响应速度的苛刻要求,提出极点重置理论改善滤波器品质,寻求最佳滤波性能;设计了一种正交锁定放大电路同时完成对磁场畸变信号幅值和相位信息的直流形式输出,提高焊缝跟踪传感器的精度。(3)用实验的方法验证信号处理电路设计的正确性和有效性,并且在此基础上通过测量能够表征磁场畸变信息的感应电压信号对垂直焊缝方向一定区域内的磁场分布规律进行验证;同时设计了开方电路完成对焊缝位置信息的提取。更多还原

【Abstract】 As welding forming technology permeate to various areas of the mechanical manufacturing, development and application of new type welding automation technology will play huge role of national economy,and seam tracking technology is the important aspect of welding automation research.The narrow interval I type butt weld which comman used in engineering usual lack of stable and effective method of tracking, combined with the high frequency alternating magnetic fields measurements (ACFM) technology in use at Non-destructive testing fields, designing and developing a new electromagnetic sensor based on the principle of ACFM applied to seam tracking.In this paper,through the modeling of sensor,s space magnetic fields,focusing on that research the internal relationship between welding line position and magnetic field distortion signal which cause by welding line;and according to the magnetic fields signal characteristic of low SNR and the requirement of welding environment design signal processing circuit to pick up accurately required signal,meanwhile simulate part of the circuit to optimization. The main research content as follows:(1) Analyzed the basic theory and feasibility of ACFM seam tracking sensor. Analyzed the basic principle and working process of ACFM technology, and established the simplified mathematical model of space magnetic fields, completed the three-dimensional space each direction induction strength theory calculation; Study the magnetic fields distribution rule of each point in the same horizontal plane along welding line direction,get the location information of weld starting and terminal point; Study the magnetic fields distribution rule within a certain region along welding line vertical direction, get the direction and amplitude information of weld deviation, fitting for distribution curve with numerical analysis method, calculate the approximate function relationship between the magnetic field strength and weld location; finally designed work flowchart about seam tracking sensor to collect magnetic fields distortion signal.(2) Designed signal processing circuit based on differential amplifier、50Hz power frequency trap and high order no drift low pass filtering, and simulated using MATLAB/simulink; according to analog trap is unable to filter out the residual power frequency harmonics,designed the whole coefficient much stopband band-stop digital filter that with the characteristic of high stopband selectivity and low signal distortion degree; according to complex welding environment and real-time demanded of tracking system,ask for the filter have high stability and response speed,offer the theory of reset filter pole to improve filter quality, seek optimal filtering performance; designed a kind of orthogonal lock-in amplifier circuit to finish DC form output of magnetic fields distortion signal amplitude and phase information simultaneously, improve the accuracy of seam tracking sensor.(3) To proving the correct and effective of signal processing circuit with experiment,and on this basis measuring the induced voltage signal which can indicate magnetic fields distortion information,to proving magnetic fields distribution rule within a certain region along welding line vertical direction; and designed extracting square root circuit to obtain welding line location information.更多还原