Realizing precision pulse TIG welding with arc length control and visual image sensing based weld detection

Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all hardware circuit, arc voltage during peak current stage is sampled and integrated to indicate arc length, deviation of arc length and adjusting parameters are calculated and output to drive a step motor directly. According to the features of welding image grabbed with CCD camera, a special algorithm was developed to detect the central line of weld fast and accurately. Then an application system were established, whose static arc length error is ±0.1 mm with 20 A average current and 1 mm given arc length, static detection precision of weld is 0.01 mm , processing time of each image is less than 120 ms . Precision pulse TIG welding of some given thin stainless steel components with complicated curved surface was successfully realized.

Determination of Surface Roughness in Wire and Arc Additive Manufacturing Based on Laser Vision Sensing

Wire and arc additive manufacturing(WAAM) shows a great promise for fabricating fully dense metal parts by means of melting materials in layers using a welding heat source. However, due to a large layer height produced in WAAM, an unsatisfactory surface roughness of parts processed by this technology has been a key issue. A methodology based on laser vision sensing is proposed to quantitatively calculate the surface roughness of parts deposited by WAAM.Calibrations for a camera and a laser plane of the optical system are presented. The reconstruction precision of the laser vision system is verified by a standard workpiece. Additionally, this determination approach is utilized to calculate the surface roughness of a multi-layer single-pass thin-walled part. The results indicate that the optical measurement approach based on the laser vision sensing is a simple and effective way to characterize the surface roughness of parts deposited by WAAM. The maximum absolute error is less than 0.15 mm. The proposed research provides the foundation for surface roughness optimization with different process parameters.

Computer-based sensing and visualizing of metal transfer mode in gas metal arc welding

Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of the welding current and arc voltage with high speed imaging of the metal transfer. It can simultaneously display the metal transfer processes and waveforms of electrical welding parameters in real-time The metal transfer videos and waveforms of electrical welding parameters can be recorded. Metal transfers under various welding conditions have been investigated with the system developed.

Arc light sensing of droplet transfer in pulsed GMAW process and its mechanism

A new method and if.''principle .fi)r 's*ensin.q dry)Plet iran.5/dr in aide W ')/ steel and aluminum alloy have been researched in this paper. A practical arc light sensing and controlling system has been developed. The reliability of the arc light characteristic signal that indicates droplet detachment and the control accuracy of the system have been verified using high-speed photography Based on the mathematical model set up in the paper, the mechanism of the signal and relative phenomena were analyzed The parameters, which influence arc light radiation were given and the limitation of this sensing method was discussed.

Vision sensing of P-GMAW weld pool using narrow band filters with different center wavelengths

The selection of narrow band filter＇s center wavelength has an important influence on the quality of the weld pool image captured in passive vision mettmd for controlling arc welding process. In this paper, 29 narrow band filters with different center wavelengths ranging from ultraviolet to near infrared wavelength were used to capture images of weld pool during both the peak current period and the base current period of P-GMA W （ pulsed gas metal arc welding）. The experimental results showed that the filters with near infrared center wavelength could weaken the arc most during the peak current period, while during the base current period the entire weld pool could be seen with the filters with wavelength above 600 nm. The camera spectral response and the radio of arc to weld pool emission were considered to analyze the phenomenon of experimental results.

Simultaneous observation of keyhole and weld pool in plasma arc welding with a single cost-effective sensor

The dynamic behaviors of the keyhole and weld pool are coupled together in plasma arc welding, and the geometric variations of both the keyhole and the weld pool determine the weld quality. It is of great significance to simultaneously sense and monitor the keyhole and the weld pool behaviors by using a single low-cost vision sensor in plasma arc welding process. In this study, the keyhole and weld pool were observed and measured under different levels of welding current by using the near infrared sensing technology and the charge coupled device （CCD） sensing system. The shapes and relative position of weld pool and keyhole under different conditions were compared and analyzed. The observation results lay solid foundation for controlling weld quality and understanding the underlying process mechanisms.

基于电流多特征融合的窄间隙P-GMAW摆动电弧传感焊缝跟踪方法

电弧传感是实现窄间隙焊接焊缝跟踪的主要方式之一。针对电弧传感稳定性差、可靠性低的问题,提出融合摆动周期内电流信息的多个统计学特征进行偏差提取的方法,克服单一数据特征容易受到电弧稳定性影响、导致传感精度下降的问题。首先,提取电流信号的多个时域特征,计算特征矩阵与偏差矢量相关性;然后,取相关性高的特征用主成分分析的方法进行融合,取前两个主成分作为观测数据;最后,基于多分类的支持向量机模型对其进行分类试验。试验结果表明最大误差为0.2 mm,0.1 mm以内的误差占93.75%。该方法对比传统方法精度有所提升,对比神经网络方法,所用训练样本少,训练过程更加简单。

惯性空间TDI相机长弧段星源主动扫描设计

为了有效扩大惯性空间观测的幅宽范围和成像信噪比,提出了一种基于星等与光学多参量的映射函数的卫星与载荷姿频协同补偿的TDI相机长弧段星源主动扫描设计方法。首先,基于黑体辐射能量密度公式,构造TDI光学参量与极限探测星等之间的映射函数;然后,采用齐次坐标变换和欧拉轴最优路径规划方法,建立惯性空间卫星恒速机动和载荷动态实时补偿的长弧段星源扫描成像模型,完成动态星源无拖尾高信噪比成像。最后,基于平行实验理论,搭建由TDI相机和动态星源模拟器组成的实验系统,并完成了扫描成像实验和误差分析。实验结果表明,本体坐标系相对惯性坐标系的欧拉角速率为8.5(°)/s时,积分级数为96,TDI相机行频为1 kHz,成像时长10 s,TDI相机成像过程中星图成像信噪比最大值为7.325,扫描区域立体角为5.4232 rad。惯性空间TDI相机长弧段星源主动扫描可实现对星源高信噪比成像,并大幅拓展了成像观测范围。

基于ArcGIS和Flex的遥感影像发布系统设计与实现

设计了基于Arc SDE空间数据管理、ArcGIS Server REST地图服务、Flex富客户端可视化查询等关键技术的遥感影像发布系统架构。介绍了系统中显示层、逻辑层、服务层和数据层等结构,利用中间件实现了空间数据库信息到客户端可视化的工作流程。开发实现了遥感影像发布系统,测试结果表明,系统可视化和交互效果好,便于扩展和维护,具有较高的应用价值。

基于Erdas和Arc/Info的矿区遥感影像信息提取技术

利用ERDAS Imagine 8.5对航片及地形图进行几何校正;经过影像粗解译和野外实地调查,对研究区土地利用现状进行分类并建立起解译标志;以ARCINFO GIS 9.0为平台,采用其中的ARCEDIT模块作为解译的基层模块,通过目视解译的方法对影像进行特征提取,结合Arcview3.3进行数据分析及图形整饰,达到图形分类、数据和图形输出的目的。由于航片分辨率高、控制点选取合理以及解译工序的合理安排,解译精度较高。

基于Arc Engine的青藏高原生态地质环境遥感监测数据库系统建设

首先介绍了青藏高原生态地质环境遥感监测数据库系统的课题背景,对于ArcEngine的开发技术进行了重点介绍;然后在分析数据背景的基础之上,对青藏高原生态地质环境遥感监测数据库的设计思路进行了详细描述,对系统的主体功能模块展开了全面剖析,列举分析了系统实现上的各个关键技术;最后,对Arc Engine的空间数据库开发进行了总结并提出了一些建议。

应用Arc/Info建立湖北省区域稳定性评价空间数据库

以Arc/Info为基本工具 ,以遥感信息为获取、更新数据库数据的主要信息源 ,结合前人地学资料 ,建立了湖北省区域稳定性评价空间数据库 ,阐述了该空间数据库的内容、功能。

自供能低频振动控制传感器的设计与制造

针对弧形结构能量采集器进行了研究和构建,该采集器实现了压电、摩擦纳米发电机之间的整合,可用于实现振动机械能到电能之间的转换,从而实现对小型传感系统的供电,弥补了传统供能方式的弊端。在研究过程中,测试了该采集器的输出性能,划分为压电单元、摩擦单元两部分,二者整流之后的输出短路电流依次是0.9μA和1.25μA,开路电压依次是10 V和60 V。该采集器除了可以实现对电容充电的功能之外,同样可以驱动50个并联的LED。相对于传统的能量采集器,其可以对不同方向的机械能进行采集,因此适用性更强,适合于应用到小型器件供能中。

应用Arc/Info建立湖北省区域稳定性评价空间数据库

GIS是获取、检索、分析、处理空间数据的数据库管理系统 ,是研究空间对象的有力工具。本文利用 GIS软件 Arc/Info为基本工具 ,以遥感数据作为获取、更新数据库数据的重要信息源 ,结合前人的地学资料 ,建立了湖北省区域稳定性评价空间数据库 ,阐述了该空间数据库的内容、功能、应用和意义。

Spectrum-Sensing Method for Arc Fault Detection in Direct Current System with Lithium Batteries

We mainly study the detection of arc faults in the direct current (DC) system of lithium battery energystorage power station. Lithium battery DC systems are widely used, but traditional DC protection devices areunable to achieve adequate protection of equipment and circuits. We build an experimental platform based onan energy storage power station with lithium batteries. Then, the data collection of normal current and arc-faultcurrent is completed under multiple conditions, and the waveforms of obvious and weak signals as the arc occursare presented. We analyze the principles and application range of several common spectrum-sensing methods andstudy the feasibility of applying them to the arc detection field. Finally, the covariance absolute value detectionalgorithm is selected, and the average value of the current is filtered out to make the algorithm adapt to the arcdetection field. The result shows that the detection probability in 500 sets of experimental data has reached 98%.

基于Arc Hydro Tools的广西小流域划分研究

为实现广西地区小流域的科学管理,加快水土保持信息化建设,以25 m分辨率DEM为基础,根据广西地形地貌特点,结合行政区划、水系分布等,对广西地区进行了小流域划分研究。为此,采用Arc Hydro Tools水文数据模型建立小流域自动划分模型进行初步划分,并针对平原区、海岸带等自动划分效果不理想的区域,利用人工处理方式对该区域进行修正。经过拓扑检查、属性编码和质量控制后,最终完成对全广西共计9 631条小流域边界的提取。结果表明:所提取小流域面积大多集中在10~50 km^2之间,无小于3 km^2和大于100 km^2的小流域,符合标准规范;自动化处理模型可对小流域进行快速划分,处理面积达到82.88%;有针对性的人工处理可提高划分精度,使得结果更为理想。研究成果对小流域信息化建设、水文模拟具有重要参考价值。

The characteristics of welding currents in a rotating arc leadtandem GMAW process and the weld-seam tracking

Tandem gas metal arc welding （ T-GMAW） process shows a high deposition rate that up to three times o f the single electrode GMAW, so the welding speed could be significantly increased in this process. However, the majority o f this process applications are based on the pre-programmed robotic welding, which does not allow them to track the seam real-time during welding. Rotating arc sensor, sensing the seam position by detecting the changing of welding currents, has been widely adopted in the automatic robot welding process. It is proposed in this paper to integrate the rotating arc sensor with a trailing torch to develop a new approach of rotating arc lead tandem gas metal arc welding （RLT-GMAW） process. The characteristics of the welding currents in the proposed new welding process were firstly studied, and then a self-turning fuzzy control seam tracking strategy was developed for the mobile robot automatic welding. The experimental results showed that the proposed RLT-GMAW process had an excellent seam tracking performance and high welding deposition rate. Even if there were some electromagnetic interactions between the two arcs, the deviation of the welding seam could also be reflected by the fluctuation of the welding currents on the leading arc once the correct welding parameters were selected. Based on the detected deviation, the welding tracking experiments showed that the proposed self-turning fuzzy controller had a good performance for the RLT-GMAW process seam tracking.

Penetration control by weld pool resonance during gas tungsten arc welding

Presents penetration control by weld pool resonance which occurs when the natural frequency of weld pool is equal to the frequency of sine wave current while the weld pool is excited into oscillation by superimposing sine wave current with definite frequency or regular frequency on DC current, and experiments carried out on detecting resonance signals during both stationary and travelling arc welding with variant frequency pulse current, and concludes with experimental results that penetration control can be realized by weld pool resonance when welding speed is lower than 80mm/min, and this control method is applicable to welding thin (0.5～3.0 mm) plates of carbon steel, low alloy steel, high strength steel and superhigh strength steel, and suitable for alternating polarity welding of stainless steel, titanium alloy steel and aluminum alloy.

基于P-GMAW摆动电弧传感的窄间隙坡口宽度自适应焊接

针对窄间隙自动化焊接过程中,组对误差、焊接热变形等因素导致的坡口宽度不一致问题,本文提出采用电弧传感方式对坡口宽度进行检测,并根据检测结果调节工艺参数,保证焊接质量的方法。通过研究坡口宽度偏差的提取算法,分析窄坡口条件下脉冲熔化极焊接的峰值电流、基值电流和平均电流信号的传感特征,提出以脉冲周期内的电流均值作为特征信号,利用侧壁平均法进行偏差提取的传感方式;确定了坡口宽度变化时,焊枪摆幅、焊接速度的调控方法,实现了适应坡口宽度变化的自动化焊接。窄间隙焊接试验表明,上述方法能够有效识别坡口宽度变化,及时对摆幅、焊速进行调整,可在坡口宽度变化时,保证侧壁熔合质量和焊层厚度均匀。研究结果对单道多层窄间隙焊接实现焊接自动化,保证焊接质量具有一定的参考价值。

基于结构光视觉的GTAW送丝位置实时传感技术研究

核电反应堆冷却剂管道(主管道)是连接反应堆压力壳与蒸汽发生器之间的主要承压设备,被称为核电的“主动脉”.主管道焊接通常采用钨极氩弧焊(gas tungsten arc welding,GTAW)工艺,通过轨道小车进行全位置焊接.然而,受限于坡口的一致性以及设备的稳定性,焊丝与熔池之间的相对位置(简称为送丝位置)在焊接过程中不可避免地出现偏移,破坏了熔池稳定,进而对焊接质量造成严重影响.此外,焊接过程中的高亮弧光以及高温也进一步加大了送丝位置传感的难度.针对以上问题,本文基于结构光视觉传感法,通过分析送丝位置对熔池形貌的影响机制,研究熔池形貌与结构光反射图样之间的对应关系,获得一种能够有效判断主管道GTAW焊接过程中送丝位置的传感方法.试验结果表明,结构光视觉传感技术能够利用熔池表面的镜面特性,将熔池表面的振动状态放大.当送丝位置位于熔池前端时,在熔池前端出现凹陷,并且反映为反射图样右端位置的点阵集中.当送丝位置位于熔池内部时,根据焊丝熔化状态又分为大电流和小电流两种情况:当电流较小时,焊丝在熔池与电弧热量的共同作用下熔化,使得熔池内部出现凹陷,并反映为反射图样中部的点阵集中;当电流较大时,焊丝在电弧热量的作用下熔化,滴入熔池并引起熔池振荡.因此,基于结构光视觉技术能够有效地获取焊丝与熔池的相对位置关系.