应用联合时频分析研究CO2焊接过程中的电信号

CO2焊接过程的电弧电压、焊接电流信号蕴含了丰富的焊接信息.利用联合时频分析对CO2焊接过程电信号进行研究,分析了短时傅里叶变换窗函数的选择对谱图的时频集聚性的影响,并选择汉宁窗获得了较好的时频集聚性.为了获得CO2焊接电信号中短路过渡的信息,尝试利用时频分析谱图对焊接试验中采集到的几组焊接电流信号进行分析,研究了其能量分布及熔滴过渡的特征,并利用联合时频分析三维谱图,对采用不同焊接参数获得的电弧电压信号进行对比.结果表明,利用联合时频分析对CO2焊接过程电信号进行分析,能够获得更多的有价值信息,该方法具有较好的研究应用前景.     

基于电信号监测的可控自触发电弧图像采集系统

基于高速摄像机触发模式的特点,提出了一种基于电信号监测的可控自触发电弧图像采集系统. 介绍了系统硬件平台组成和软件总体框架,论述了以电信号有效值为监测条件的相关控制触发算法,叙述了电信号和电弧图像同步采集的具体实现方法,并以表面涂有油污的试样进行了电弧图像采集系统的试验验证. 结果表明,该系统能够有效基于电信号可靠自动触发高速摄像机拍摄,抓捕涂有油污表面的过渡过程信息. 相比于正常焊接过程,试样表面存在油污时,过渡周期明显增加,电弧形态呈现出较大的发散性.     

弧焊过程监测嵌入式分析系统

以焊接过程中的焊接电流、电弧电压为信号源,设计了基于STM32的多通道高精度数据采集系统,通过以太网总线实现了局域网内焊接过程信息的实时监测和数据传输;设计了一套焊接过程信息数据分析软件,用于研究焊接过程电信号表现形式与焊接质量的关系,进而实现焊接质量的定量评价,为当前自动化与机器人焊接的信息化提供了一种定量分析工具。     

点焊过程电信号分析系统的研究

点焊过程电信号分析系统是研制高质量焊接设备的一种重要测试技术手段.基于Windows环境、高速数据采集卡PCL1800和工控机通用平台,采用Visual C 6.0开发出高速多功能点焊过程电信号测试分析软件.该系统能精确测定点焊过程的电极间电压和焊接电流波形,并提取出焊接过程动特性的特征信息,从而为高性能焊机的研制和焊接参数的优化提供了一个强有力的工具.     

弧焊过程信息监测及工程化应用

以弧焊过程中焊接电流、电弧电压为信号源,针对现有弧焊监测设备的局限性,设计一种小型便携,集采集、显示、存储多功能为一体的弧焊监测设备,并根据企业现代化发展需要,设计配套的综合信息管理、数据分析与评估功能的应用软件,实现焊接过程大数据信息的快速处理,用于优化焊接生产过程,实现对焊接质量信息的可记录、可分析、可追溯、可评估。     

焊接监测技术在轨道客车焊接中的应用

介绍了焊接监测技术的基础功能,以及在轨道车辆焊接中的实际应用情况。实践证明:焊接监测技术的焊接过程监测功能和焊接信息管理功能能够实现对轨道车辆焊接部件焊接过程监测,以及对焊接作业数据的记录、统计和分析,对于加强焊接质量控制、掌控焊接生产信息、提高焊接管理水平都具有重要价值。     

面向水下焊接电信号的粒子群优化小波软阈值去噪法研究

为降低噪声干扰以及提高检测精度,提出一种针对水下焊接电信号的基于粒子群优化的小波软阈值去噪方法。通过对信号进行小波分解,以信噪比作为评价指标,不断迭代进行全局搜索最优阈值从而完成信号去噪,并分别进行仿真及实测水下焊接电信号的去噪实验。结果表明,提出的算法具有信号信噪比更高、均方根误差更小、能有效保留信号的细节信息等优点,有利于水下焊接电信号特征的提取,从而为水下焊接质量在线监测提供基础。     

搅拌摩擦焊接监控系统设计

基于对搅拌摩擦焊接过程的分析,设计了搅拌摩擦焊接专用的状态监测系统及控制系统.监控系统的软件结构采用开放系统结构设计,利用设计的上位机软件可以对焊接参数及监测量的记录存储,并对其进行统计分析,方便试验人员建立焊接过程的精确数学模型、优化焊接参数和研究焊接的智能控制算法,监控系统的实现提高了焊接自动化程度.     

脉冲MIG焊不稳定过渡过程的观察与分析

基于高速摄像和电信号分析系统,采集了一定焊接工艺参数下脉冲MIG焊焊接过程的电信号,借助电信号小波分析设备对不稳定焊接过程进行了宏观分析,并对焊接熔滴过渡过程中的不稳定现象进行了高速摄像观察.观察发现,脉冲MIG焊不稳定焊接过程呈现出多种熔滴过渡形式,过渡熔滴形状多样,熔滴尺寸不均匀,熔滴形成过程中重心不稳,熔滴爆炸引起飞溅以及熔池振荡.通过对焊接过程不稳定现象的观察与分析,指出焊丝熔化能量的随机性以及熔滴上综合作用力的随机性是熔滴尺寸具有不确定性的根源.对脉冲MIG焊焊接过程不稳定现象的研究将有利于对焊接工艺性能进行有效控制.     

电抗器参数对弧焊过程动特性的影响分析

利用自行研制的焊接动态电孤小波分析仪时KR焊接电源的焊接过程的引孤、中间过程、熄孤的电信号进行采集.针对不同的电抗器材料,采用数理统计方法提取焊接过程电流波形的特征信息,从而对焊接过程的动特性进行分析.结果表明,该方法能综合反映孤焊电潭的动特性,可为改进焊接工艺和波形控制方法提供依据.     

Pulsed eddy current signal processing method for signal denoising in ferromagnetic plate testing

A signal denoising method is presented for ferromagnetic material pulsed eddy current (PEC) testing signal. The method firstly performs multiple measurements, and obtains an averaged signal and then transforms the averaged PEC signal from Cartesian domain to double logarithmic domain by the developed algorithm. A median filtering process is then performed for double logarithmic domain signal. An invert transform is optional to be performed to transform the processed signal from double logarithmic domain back to Cartesian domain. A signal-to-noise ratio (SNR) improvement quantification method is applied to evaluate the SNR improvement. The performance of the method is then verified by experiments. The effects of signal averaging number and median filter’s order are discussed. Experiment results show the method is able to increase SNR by about 40 dB.     

电子信号接收器复合模具设计

介绍一种铝板一次完成落料、拉深成形、冲孔3道工序的复合模具,该模具改变了电子信号接收器盖体传统的多工序生产方式,降低了生产成本,提高了产品质量和生产效率.     

电弧传感器小波信号处理系统

利用小波分析所具有的良好时域、频域局部性的特点，结合DSP(数字信号处理器)技术，设计了基于小渡变换的带通滤波器，并把此滤波器直用于旋转电弧的信号处理。该滤渡器的中心频率可以根据旋转频率中自动调整，而带宽可以通过改变软件参数来调整。试验结果表明，电弧信号经该滤波器处理后，其信噪比得到了大大提高。     

FANUC Oi倍率信号的PLC控制

本文介绍了一种用于FANUC Oi系统,通过PLC数据表的设定,可以任意改变倍率值的进给倍率控制PLC程序.     

GPR signal de-noising by discrete wavelet transform

Ground penetrating radar (GPR) is a non-destructive investigation tool used for several applications related to civil infrastructures; including buried objects detection and structural condition evaluation. Although GPR can be effectively used to survey structures, signal analysis can be sometimes challenging. The GPR signals can be easily corrupted by noise because the GPR receiver has usually an ultra-wide bandwidth (UWB). The noise collected by the system can easily mask relatively weak reflections resulting from the inhomogeneities within the surveyed structure; especially when they are at a relatively deep location. This paper presents the use of discrete wavelet transform (DWT) to de-noise the GPR signals. Various mother wavelets were used in this study to de-noise experimental GPR signals collected from flexible pavements. The performance of wavelet de-noising was evaluated by computing the signal-to-noise ratio (SNR) and the normalized root-mean-square error (NRMSE) after de-noising. The study found that wavelet de-noising approach outperforms traditional frequency filters such as the elliptic filter. At the same level of decomposition, the Daubechies order 6 and Symlet order 6 outperform the Haar and Biorthogonal mother wavelets when de-noising GPR signals by soft thresholding.     

焊接电弧声信号降噪技术

焊接电弧声作为焊接过程质量监控潜在的源信号之一,在传感、转换以及传输等过程极易受到设备、环境噪声的污染,从硬件、软件两个方面分别对其进行降噪处理.硬件方面包括低噪声传声器、接地装置、消除直流偏移的交流耦合、采用仪器放大器、抗混叠滤波以及屏蔽电缆等措施;软件方面运用基于多尺度分析理论的 Mallat 算法,实现了基于 LabVIEW 的电弧声小波分解重构降噪处理.结果表明,电弧声信号经硬件、软件降噪后,不仅"毛刺"得到有效滤除,而且波形突变部分更加清晰,信噪比大幅度提高,为后续电弧声信号特征分析提取以及利用电弧声来监控焊接质量提供技术基础.

Abstract：

Arc sound is well known as one of the potential source signals for controlling of welding process quality, which is vulnerable to noise pollution by equipment and environment in sensing, conversing and transmission. Therefore, it is necessary to reduce arc sound noise by hardware and software. Hardware measures include low-noise microphone, grounding devices, eliminating the DC offset exchange coupling, equipment amplifiers, anti-alias filtering and shielding cables, etc. In terms of software, by using Mallat algorithm based on principle of multi-resolution, the noise of arc sound signal is reduced via wavelet decomposition and reconstruction based on LabVIEW. The results show that the burr of arc sound is effectively filtered out, the mutations of waveform are clearer and the noise ratio is obviously increased. The reducing noise means provide technical basis for extracting characteristics of arc signal and monitoring welding quality via arc signal.     

传感器输出转换的改进

传感器输出电压ui中包含着较多成分的噪声电压,为了减小噪声电压的影响,我们将ui转换为平均值uo,取得了较好的效果。     

An adaptive channel equalization algorithm for MFL signal

Magnetic Flux Leakage (MFL) method is one of the most robust non destructive evaluation (NDE) techniques employed by in-line inspection (ILI) tools such as an instrumented pipeline inspection gauge (IPIG), to assess the health of buried cross country pipelines, carrying petroleum products. An array of hall-effect sensors disposed ideally at the magnetic neutral plane of a permanent magnet resident in IPIG, cling to the inner surface of the pipe wall, measuring the change in leakage flux density. However, ideal sensor disposition is almost never satisfied and each sensor measures differently. In this paper, a new scheme of channel equalization is proposed for MFL signal so as to correct sensor misalignments, which eventually improves accuracy of defect characterization. Also, for the above, a baseline estimator is developed, which estimates the baseline of MFL sensor output signal under pipeline defects and key features (wields, sleeves, valves). The scheme proposed is adaptive to the effects of error in the disposition of the sensor due to manufacturing imperfections and sensor movements (bounce/axial shift near a weld). The algorithm is tested on field data acquired by an IPIG running in a commercial pipeline. The final result obtained shows excellent signal recovery and noise cancellation.     

虚拟信号测量仪在焊接技术中的应用

通过虚拟信号测量仪可测量电信号和非电信号.电信号部分显示器可直观地显示采集的波形,并通过相应的函数模块处理,得到波形的直流分量、标准频率、峰值、平均值和有效值.非电信号部分的显示器按时间顺序以波形的形式显示所测得的值的历史变化趋势,并得出当前时间段信号的最大、最小和平均值,应用于焊接质量的判断.