基于过程信息统计分析的微点焊过程监控

为加强对漆包线-铜箔微点焊过程的监测,便于管控实际焊接生产质量,构建了微点焊过程监控平台。基于过程电信息数据,采用最小二乘法对微点焊电极全生命周期动态电阻变化规律进行建模,确定电极烧损状态变化临界点,实现电极烧损状态监测;利用统计过程控制技术,通过生产过程电信号均值-标准差图,实现微点焊过程异常信息监测与质量管控。     

点焊过程力学特征的有限元分析

电阻点焊过程中的力学特征对焊点性能和焊接结构的质量有重要影响。文中基于ANSYS有限元系统，建立二维轴对称热弹塑性有限元模型，对点焊过程中的力学特征进行分析。分析中将预先得到的点焊瞬态温度场作为节点温度载荷施加于模型上，同时考虑随温度变化的材料性能及其塑性行为。通过分析得到结合面和电极一工件界面上的接触压力、点焊接头中的应力、应变、变形以及电极位移等力学特征的分布及变化情况。同时参考分析结果进行粘接点焊的试验研究，表明粘接点焊可以显著提高结构的强度和疲劳寿命。     

基于MSC.NASTRAN的点焊模型及其比较分析

点焊是汽车车身结构常用的一种连接方式,为对这种结构进行有限元分析必须建立相应的点焊模型。本文介绍了MSC.NASTRAN中常用的3种点焊模型,并用一个例子说明了不同的点焊模型对分析结果的影响。     

电阻点焊过程智能控制的研究

介绍了20世纪90年代以来人工神经网络技术、模糊逻辑控制、专家系统在电阻点焊控制中的应用，分析了这些研究成果的特点及其局限性；结合已有的研究成果，对有待解决的问题指出了解决途径，并展望了该方法的研究前景。为电阻点焊过程控制的进一步研究提出了参考依据。     

基于热膨胀的点焊实时控制系统的研制

提出了一种在恒流点焊控制器基础上加入电极热膨胀位移控制规则的方法。利用激光位移传感器及其外围电路，建立了热膨胀的微机点焊控制系统，并使用屏蔽电路实现恒流控制与热膨胀控制的相互切换。实验结果表明，该系统具有自适应特性，能够实时的实现点焊过程中的质量监控。     

薄板点焊热过程的有限元分析

基于ANSYS有限元分析系统,建立用于点焊瞬态热过程分析的电热耦合有限元模型,考虑随温度变化的材料特 性参数、相变以及对流边界条件等,对点焊过程中的接触问题进行适当简化。通过对低碳钢薄板点焊过程的分析,得到 点焊接头的温度场及各部位的热历程,模拟了焊核形成过程,求得焊核及热影响区的形状和尺寸。     

基于ANSYS的搅拌摩擦点焊机器人的有限元分析

对搅拌摩擦点焊机器人建立了三维模型,在对其关键部件模型简化后,通过工程分析软件ANSYS进行了网格划分、模态分析和静力分析,得到了各部件的固有频率、振型及应力、变形分布等情况,分析结果为进一步的优化设计提供了理论依据。     

铝合金点焊过程的铜铝合金化研究

观测了LF2铝合金电阻点焊初期至达到电极寿命时焊点表面及Cr—Zr—Cu电极端面宏观形貌的连续变化过程。采用扫描电子显微镜(SEM)，对机加工状态及抛光处理的电极在点焊铝合金后进行了电极端面背散射分析，对机加工状态的电极在点焊铝合金后又进行了电极端面横向及纵向线扫描分析。采用X射线衍射仪，对沿电极轴向的3个不同电极端面进行了X射线衍射物相分析。结果表明，点焊初期，焊点表面即出现局部熔化及电极端面出现明显凹凸不平，电极端面的形貌及其尺寸发生变化，焊点表面成形质量恶化，电极端面加工状态对电极端面铜铝合金化影响不大，点焊过程电极端面存在较多铝，发生了铜铝合金化反应，合金化产物主要是铜铝金属间化合物(CuAl2)。     

120 kg点焊机器人试验模态分析

用试验模态分析方法对A型和B型两台点焊机器人的动态特性进行了分析研究,得出机器人在典型位姿下的低阶固有频率。通过对机器人在不同位姿下的模态特性分析,指出机器人整体结构中相对薄弱的环节,并指出,机器人各构件的质量和刚度分布应相互协调和匹配,其合理与否对机器人的动态性能有较大影响。最后提出了机器人结构设计的改进方案。     

点焊接头疲劳研究综述

对点焊接头疲劳研究近几十年的发展进行全面的综述。从数值分析、试验分析、有限元分析和疲劳评估方法等4个方面系统梳理和综述点焊接头的疲劳研究成果,将点焊静态理论、局部应力、结构应力和断裂力学等数值分析方法进行归纳总结;从静态试验、拉剪疲劳试验、剥离试验和缺口试验等试验方法中研究点焊接头失效模式、失效机理和疲劳寿命;对8种点焊接头有限元模型的特点、建模方法、适用范围进行了对比综述,认为C_WELD和C_BAR模型适用于大型点焊结构中;对载荷-寿命法、名义应力法、热点应力法、等效结构应力法等多种点焊接头疲劳评估方法的适用条件、适用对象、评估效果等进行归纳总结,认为等效结构应力法值得在工程领域进行推广应用。最后对存在的问题和进一步研究方向进行评述和探讨,对点焊接头更深入的疲劳研究具有一定的指导和帮助。     

一种气动点焊模拟系统

为模拟工业现场的工件焊接,采用典型气动元器件,开发了一套气动点焊模拟系统,该系统主要完成工件的传送和点焊。介绍了系统的整体结构、动作流程、气动回路以及采用可编程序控制系统的软硬件设计。所设计的气动点焊模拟系统典型美观,运行可靠,满足各项要求。     

Characterization of nugget nucleation quality based on the structure-borne acoustic emission signals detected during resistance spot welding process

Acoustic emission signals detected during the resistance spot welding of aluminum alloy were studied in order to assess the characterizations of welding process, the characterizations of the effect of welding parameters to nugget nucleation and the characterizations of the nugget quality by the analysis to acoustic emission signals. The results showed that the physical phases of nugget nucleation can be characterized by the acoustic emission signals detected during the resistance spot welding process. The effects of welding current and current duration to nugget nucleation can be characterized by the characteristic parameters of acoustic emission signals. The characteristic parameters of acoustic emission signals had a better relevance to nugget dimensions and weld strength, which made it possible to measure or predict the weld strength by the characteristic parameters of acoustic emission signals detected during the resistance spot welding process.     

Modeling small-scale resistance spot welding machine dynamics for process control

Electrode displacement is generally regarded as a variable that can provide real-time information useful for monitoring and controlling resistance spot welding (RSW) process quality. However, in small-scale RSW production, it is difficult to measure the displacement because its magnitude is very small. By contrast, force signals are relatively large and thus are less susceptible to measurement noise. In this article, an empirical model is proposed to simulate the dynamics of an SSRSW head with the objective of calculating electrode displacement from the variation of electrode clamping force measured during welding. The parameters in the model were determined by fitting experimental force and displacement signals with polynomials and then performing an optimization search for parameters of first-order dynamic models. To verify the models’ accuracy, they were subsequently applied to simulate the electrode displacement curves of welds with expulsion and without expulsion. The calculated displacement curves agreed well with experimental measurements, and the occurrence of expulsion was clearly indicated by the model predictions. A more comprehensive model is under construction with an objective to eliminate displacement sensor in the monitoring and control of SSRSW process.     

开放式点焊机器人控制系统设计

为解决封闭式控制系统带来的弊端,结合现场焊接机器人技术要求,设计了开放式点焊机器人控制系统,提供了分层式体系与结构化功能模块.多轴运动控制器(PMAC)用于实现机器人运动学算法,伺服放大器采取速度模式控制方式,位置环算法由PMAC完成,速度环算法在伺服放大器中完成,并实现了离线编程与三维仿真.研究结果表明:分层式系统结...     

电阻点焊的控制系统设计与应用

方矩管生产最后环节需要将成品按规格数量集中,并通过打包带包装成捆。原打包带接头采用人工焊接,焊接完成后将成捆产品通过吊装入库,因此打包带的焊接质量和效率直接影响产品转运的安全性和生产节拍。为提高方矩管打包过程的自动化程度,设计了应用于方矩管打包带接头的电阻点焊自动控制系统。系统硬件主要采用PLC、伺服控制器和电阻焊机,软件采用工控软件实现。通过理论计算和调试得到满足打包带接头焊接需求的最佳焊接参数和运行参数,经过对焊接质量的可靠性测试分析,焊接打包带能够满足成捆产品转运负荷要求。该系统在原有半自动打包机的基础上实现了方矩管的全自动打包,组态软件运行状态良好,节省了人力成本,提高了方矩管打包的效率,焊接质量稳定,焊接方式更加环保。     

Online nugget diameter control system for resistance spot welding

The aim of this paper is to provide an integrated real-time control system for resistance spot welding (RSW), which is capable of producing welds with predetermined nugget diameters. Nugget diameter is a commonly used criterion for estimating the weld quality; thus, the system can be used for online quality control of RSW. The proposed system consists of two parts: a constant current controller and an online nugget diameter estimator. The constant current controller is used to guarantee the consistency of the nugget formation and growth during the welding process, while the online nugget diameter estimator can be used as a sensor for online estimation of the nugget diameter. The proposed online nugget diameter estimator is a mathematical function of the heat energy absorbed by the weld, which is taken into account only after the time when the first melting point of a weld appears. This time can be obtained by means of the dynamic resistance curve with a high resolution. A mathematical model of the online nugget diameter estimator is proposed and realized based on the experiment results and mathematical analysis. The welding process would be terminated when the difference between the actual nugget diameter and the predetermined desired value is within a given tolerance. According to a series of experiments, the welds used in the experiments had nugget diameters, which were well within the limits and the errors were within the given tolerance.     

基于电信号与高速摄像的弧焊过程测试分析系统研究

文章针对弧焊过程复杂、非线性的特点,研制了弧焊过程测试分析系统。系统由传感器、数据采集卡、高速摄像机等硬件检测设备、光学设备和控制软件构成。该系统具有电信号采集、瞬时分析、统计分析、同步高速摄影、图像处理等功能。利用该系统对弧焊过程信号进行了测试与分析,实验表明：该系统稳定可靠,功能完善,能有效地对弧焊过程进行监测分析与质量评定。     

Data mining in resistance spot welding

Resistance spot welding is the dominant process in the present mass production of steel constructions without sealing requirements with single sheet thicknesses up to 3 mm. Two of the main applications of resistance spot welding are the automobile and the railway vehicle manufacturing industry. The majority of these connections has safety-related character and therefore they must not fall below a certain weld diameter. Since resistance spot welding has been established, this weld diameter has been usually used as the gold standard. Despite intensive efforts, there has not been found yet a reliable method to detect this connection quality non-destructively. Considerable amounts of money and steel sheets are wasted on making sure that the process does not result in faulty joints. The indication of the weld diameter by in-process monitoring in a reliable way would allow the quality documentation of joints during the welding process and additionally lead through demand-actuated milling cycles to a substantial decrease of electrode consumption. An annual, estimated reduction in the seven- to nine-figure range could be achieved. It has an important impact, because the economics of the process is essentially characterized by the electrode caps (Klages 24). We propose a simple and straightforward approach using data mining techniques to accurately predict the weld diameter from recorded data during the welding process. In this paper, we describe the methods used during data preprocessing and segmentation, feature extraction and selection, and model creation and validation. We achieve promising results during an analysis of more than 3000 classified welds using a model tree as a predictor with a success rate of 93 %. In the future, we hope to validate our model with unseen welding data and implement it in a real world application.     

基于FPGA图像处理的内窥镜焊点检测系统

电子内窥镜作为现代医疗仪器中的重要设备,随着产量的不断增加,实现内窥镜信号线自动化焊接已成为一个必然趋势。为精确高效采集内窥镜镜头模组的焊点坐标,设计了一种基于现场可编程逻辑门阵列（field programmable gate array,FPGA）图像处理的内窥镜焊点检测系统。整个系统以OV5640作为图像采集器件对目标板的图像数据进行采集,通过Verilog HDL硬件描述语言进行图像处理,实现焊点检测和瑕疵判别算法的设计。硬件测试结果表明,该系统能实时采集焊点坐标并检测焊点之间的瑕疵,采集到的焊点坐标最大误差小于0.1 mm,检测精度高,实时性强,具有广泛的应用前景。