Development of high frequency pulse power source using two powersfor TIG welding

A high frequency pulse power source for TIG welding is developed. The structure of two powers is adopted. The by pass circuit effectively eliminates the effect of the cable equivalent inductance. The maximum frequency of the output pulse current reaches to 16 kHz . The base current and the peak current can be regulated separately.

A novel variable polarity welding power based on high-frequency pulse modulation

A new type of variable polarity welding power modulated with high-frequency pulse current is developed. Series of high-frequency pulse current is superimposed on direct-current-electrode-negative （DCEN）, which can improve the crystallization process in the weld bead as a result of the electromagnetic force generated by pulse current. Digital signal processor （DSP） is used to realize the closed-loop control of the first inverter, variable polarity output of the second inverter and high-frequency pulse current superposition.

Effect of variable polarity frequency on 2A14-T6 aluminum alloy welds using HPVP-GTAW process

Hybrid ultrahigh frequency pulse variable polarity gas tungsten arc welding （HPVP-GTAW） for 2A14-T6 high strength aluminum alloy was carried out and the effects of variable polarity frequency with constant pulse current frequency 40 kHz on weld bead geometry, microstrueture and microhardness were analyzed. Experimental results indicate that, compared to that of the conventional VP-GTAW process, the weld depth and ratio of weld depth to width are improved significantly by the variable polarity frequency in the HPVP-GTAW process, which the ratio of weld depth to width is improved by 36% at equal variable polarity frequency of 100 Hz, and improved by 55% with that of 200 Hz. Weld microstructure and microhardness distribution are changed obviously with the increase of variable polarity frequency. In the conventional VP-GTA W process, the grains in weld central zone are coarser, and the microhardness in weld central zone and fusion zone is about 95 HV and the lowest 82 HV, respectively. The microhardness is enhanced to a certain extent both in the weld central zone and fusion zone with the variation of variable polarity frequency in the HPVP-GTAW process due to the refinement and uniformity of weld microstructure. With the variable polarity frequency of 600 Hz, the microhardness in weld central zone and fusion zone reaches nearly 110 HV and 97 HV, respectively.

Effect of pulse frequency on hardness characteristics of Al-Cu alloy HPVP-GTAW joints

AA 2219-0 Al-Cu alloy single bead welds were obtained by hybrid ultrahigh frequency pulse variable polarity gas tungsten arc welding （HPVP-GTAW） process with pulse frequency varying from 25 kHz to 70 kHz. Weld hardness characteristics which mainly depicted by microhardness and its gradient were investigated systematically. The results show that pulse frequency has a great effect on the hardness characteristics. The weld zone microhardness and its gradient with different pulse frequency present an evident fluctuant trend. The fluctuation of gradient is slight, illustrating that the mierostructure is uniform with pulse frequcncy varied from 35 kHz to 60 kHz. The fusion zone microhardness and its gradient foUow the similar trends but fluetuate greatly. Maximum value of gradient appears around the fusion boundary due to the coarse and non- uniform microstrueture. The maximum gradient at 60 kHz is only 25.5 % of that at 45 kHz. According to the study, the best hardness characteristics are achieved at 60 kHz frequency.

Numerical simulation of applied electromagnetic field and electromagnetic force in all-position welding

All-position welding is an important technology in energy sources, chemical, shipbuilding and other industries. When welding current is larger than 200 A, the molten metal tends to flow down due to the force of gravity. In order to ＂push＂ the molten metal into the weld, a new kind of U-frame excitation model, which could produce electromagnetic force to balance the gravity of the molten pool, was designed. The related parameters of the excitation model were simulated by Maxwell 3D, and the relationships between the parameters and the magnetic induction intensity were analyzed. Finally, the electromagnetic force in the molten pool was calculated, and the appropriate parameters of the U-frame excitation model were determined. The results of the simulation verify the feasibility of the all-position welding excitation model.

A computer control system for automatic TIG welding of aluminium alloy sheets

Aimed at the welding ttechnological requirements of foe missile shell,a computer control system for automatic TIG welding of aluminium alloy sheets has been developed in this paper.The hardware of the system is composed of the four sub-systems,i.e.weldingpower source,arc length controller,welding wire feeder and welding head traveller.The software of the system comprises the on-line executing program and the off-line serving program.The operating principle,specifications and control of the system are introduced.The experiments indicate that the system possesses rational hardware structure and practical software function,and has solved the problem of high frequency interference to the computer control system. Therefore,the control system can satisfy the requirements of automatic TIG welding of the missile shell.

Investigation on the communication network of long wire transmitting in remote welding

According to the characteristics of remote welding, including multiple parameters, real-time, and reliability of long wire transmitting, a distributing computer control scheme is adopted. A serial communication network between the master and the slavery computers is constructed. A synchro-control network among slavery computers is designed. Uniform message format and communication protocols are made. Considering intensive high-frequency noises at the welding zone, a quadruple check mode, including data sum check, parameter type check, welding parameters check and Exclusive OR （ XOR ） check, is adopted to assure the reliability of communication among multiple computers. Based on disturbing circuit, common circuit and sensitive circuit, the measures are brought forward to ensure the stabilization of communication network of remote arc welding by analyzing the wiring principle of anti-high-frequency interference of system bus, signal wires and shielding twisted-pair（STP） wires. The results provide the theoretical and practical references for the manufacture of remote welding robot and the quality of remote welding.

Gleeble 3500热模拟HFW焊接工艺研究

采用Gleeble 3500实验机模拟了HFW焊接过程,研究了焊缝区金属挤出温度及其硬度和组织。结果表明:挤压形变量、挤压应力的波动变化主要与焊缝区金属挤出过程及焊后冷却过程中的相变有关;试验钢碳当量越高,焊缝区金属挤出开始温度就越高,终止温度就越低,不仅影响焊接质量,而且影响生产效率。

API 5L X65 HFW钢管在海上某油田的耐腐蚀性研究

针对海上某油田不同服役年份的腐蚀工况,利用动态高温高压釜及电化学工作站,对该油田使用的API 5L X65 HFW管道进行了耐腐蚀性研究,并筛选了适用的缓蚀剂。研究表明,API 5L X65 HFW钢管的焊缝与本体材质的耐腐蚀性无明显差异,结合使用优选的缓蚀剂,可以满足该油田生产的防腐需求。

HFW管高频感应加热过程电磁热耦合数值模拟

以提高直缝焊管质量为目的,重点研究了高频感应加热过程中热影响区的温度分布对焊缝质量的影响.针对高频感应加热的特点,对ANSYS有限元软件进行了二次开发,在应用物理环境法的基础上,利用APDL语言编制了直缝焊管高频感应加热过程中电磁热耦合的命令流程序,建立了三维有限元模型,分析了电磁场和温度场的分布规律.对某厂生产的219mm钢管模拟分析,综合考虑不同的磁棒分布形式对加热效率影响和自身冷却条件.结果表明,阵列式分布的小磁棒较好,这正是与生产实际相符合的.

中频退火装置感应线圈定位和焊缝跟踪系统在HFW焊管生产线上的应用

中频退火装置在焊管生产线上的作用较大,其感应线圈对焊管焊缝的热处理效果除了取决于中频电源的设计外,还与感应线圈是否有效定位在焊缝处有着密切的关系。介绍了一种中频退火装置感应线圈定位和焊缝跟踪系统在宝山钢铁股份有限公司HFW焊管生产线上的应用情况,该系统的设备组成结构、工作原理和功能使用要点,以及该系统进行钢管焊缝跟踪和根据产品规格进行线圈定位调整的方法。实际应用表明,该系统应用效果良好,具有一定的推广价值。

HFW508直缝焊管机组的技术先进性分析

FFX成型及定径、高频焊接、焊缝热处理、无损探伤等新技术和设备的开发并应用于中直径HFW钢管生产,促进了HFW钢管生产和技术的迅猛发展。中直径HFW钢管已在海上和陆上油气输送方面得到了广泛使用。近年来,X80钢级管线管及TUF油井管的问世,为中直径HFW钢管开辟了更广泛的应用领域。以华油钢管公司扬州分公司的HFW508直缝焊管机组为例,介绍了该类机组的技术特点及先进性。

宝钢610HFW焊管机组的现状与发展

介绍了宝钢610HFW焊管机组的产品定位、工艺流程及产品开发,包括结构管产品的规格和典型壁厚结构管拉伸性能、套管产品规格及其力学性能、管线管产品及其力学性能。结果表明,宝钢610HFW焊管机组已生产产品性能均达到或超过相关标准要求。

HFW焊管高温力学性能和热物理性能分析

针对某80钢级HFW焊管在井下作业过程中需承受不同高温下的服役环境,通过EBSD相机分析管体微观组织,测试获得了该焊管试样几个典型温度下的强度变化规律及弹性模量-温度曲线、热膨胀-温度曲线及导热系数-温度曲线等。结果表明,试样在300℃左右表现出较高的强度,在600~900℃时,杨氏模量和剪切模量降低速度较快;试样开始相变温度A_（c1）=759℃,相变转变结束温度A_（c3）=860℃,导热系数在700℃时出现极低值23.3 W/m·K。通过测试研究管体的高温力学性能和热物理性能,可为某80钢级HFW焊管在高温下的实际生产和井下安全服役提供作业参考。

中大直径HFW焊管高频接触焊接和高频感应焊接的比较

针对HFW焊管焊接采用的高频感应焊接(HFIW)和高频接触焊接(HFCW)两种焊接方式,从适用范围、能耗、产品质量成本方面作了比较。接触焊接最显著的优点就是能耗少,但质量成本比感应焊接要高;如果感应焊接配置得当,焊管厂家在成本和质量方面将取得最优化。

HFW焊管焊接HAZ宽度的影响因素

为进一步明确HFW焊管生产时影响焊接HAZ宽度的因素,根据HFW的加热原理,利用物理学方程对焊接HAZ宽度进行了定量计算。结果表明,对于一般低碳钢而言,焊接频率对于感应电流在材料中的穿透深度有一定影响,但是差别很小,采用100 kHz与200 kHz焊接时,电流透入深度仅相差0.001 mm。而影响焊接HAZ宽度的主要因素热传导深度与焊接频率无关。因此,要科学的选择焊接频率和其他工艺参数,制定出合理的焊后热处理工艺,从而保证HFW焊管的产品质量。

热轧卷板质量对HFW焊管成型及焊接的影响

为研究热轧卷板质量对HFW焊管成型及焊接的影响,从热轧卷板成分、组织、几何尺寸、外观及纵剪质量等方面进行了分析。结果表明,卷板的成分、带状组织及夹杂物直接影响HFW焊管的可焊性及性能;卷板的宽度、厚度等几何尺寸不但影响成型焊接质量,而且影响焊道毛刺的清除质量;卷板的镰刀弯、波浪弯等外观缺欠影响焊管成型和焊接稳定性,容易导致焊接缺陷的发生;卷板纵剪断面质量也直接影响焊接的质量。针对以上影响因素,从卷板冶炼、轧制及纵剪工艺等方面制定改进措施,从而为高频焊管焊接提供焊接性、纯净度、尺寸精度、外观质量优异的卷板原料,以提升焊管成型和焊接的质量。

基于Simotion运动控制系统高速铣边机在HFW钢管生产线上的应用

从工艺流程、组成结构、工作原理、控制方式等方面入手,介绍基于西门子Simotion运动控制系统的高速铣边机在HFW生产线上的应用。包括高速铣边机电气控制部分西门子Simotion运动控制器及S120驱动器、伺服电机及基恩士光栅传感器的技术应用原理,铣边机的机械组成和生产工艺,铣边机的工作原理和运动控制逻辑及功能动作。

扫描电镜在HFW焊接缺陷分析中的应用

为了对高频电阻焊(HFW)焊管的缺陷研究提供定性和半定性分析的依据,以HFW焊管为研究对象,采用扫描电子显微镜(SEM)结合X射线能谱仪对焊接过程中出现的多种缺陷,如Mn-Si系夹杂物、Mn-S系夹杂物以及Mg-Ca-Al系夹杂物进行了微观形貌及成分分析。通过全面分析,找到了引发断裂的主要原因,发现夹杂物破坏了焊接接头金属的连续性和均匀性,从而降低了焊接接头的塑韧性和综合力学性能。最后针对出现的问题,提出了防范措施。

HFW钢管产品多领域开发

HFW钢管与无缝钢管相比,具有外观尺寸精度高、壁厚均匀性好、成本低、生产效率高等优势,应用领域逐渐延伸。扬州钢管公司研发的高品质HFW钢管,在关键生产工序中的铣边、成型、高频接触焊工艺方面技术领先。铣边机采用倾斜式圆筒切削工具,切削刀直径850mm;FFX成型技术实现粗成型段轧辊的完全兼用,结构合理,钢管调型简单易行;新型双电极接触焊设备,采用弹性方式进行压力调整,降低电极对钢管表面的划伤,防止电极损坏。公司根据市场需求,努力优化产品种类,完成一系列特殊领域用管的研发和批量生产,包括K55材质低屈强比石油套管、低温站场管、矿浆输送管等,填补了国内HFW钢管应用领域多项空白。