Sensitivity analysis of rotating flux-cored arc welding process parameters

Empirical models were developed using curvilinear regression analysis to predict bead geometries of rotating fluxcored arc welding (FCAW).Parameters,such as rotational frequency,rotational radius,torch...     

Optimization of submerged arc welding process parameters for overlay welding

In this work, we evaluated the influence of welding variables on weld beads applied by the submerged arc process (SAW) with conventional current, aiming future application in overlays against corrosion. Segments of steel API 5L Gr B pipe as substrate, a 1.13 mm-diameter electrode wire of nickel alloy, classification AWS ERNiCrMo-4 (Hastelloy C-276) as filler metal, and a flux neutral, basic and crowded were used. The variables voltage, wire feed speed and contact tip to work distance (CTWD) were analysed, with the remaining parameters constant by an experimental design with full factorial design in two-level and central points. Statistically significant and predictor mathematical models for response dilution and average current were obtained. However, for the response reinforcement/width, the model was characterized as statistically significant, but not predictive, and containing a lack of fit. The CTWD was the most significant variable reducing the dilution.     

Effect of heat input on weld bead geometry of submerged arc welded ASTM A709 Grade 50 steel joints

A series of measurements was carried out on specimens of submerged arc welded plates of ASTM A709 Grade 50 steel to determine how variation in heat input achieved using single and double wires affected bead reinforcement, bead width, penetration depth, contact angle, heat affected zone (HAZ) size, deposition area, penetration area and total molten area. The level of dilution and different melting efficiencies were calculated and their variation with heat input was analyzed based on the acquired measurements. The cooling time from 800 to 500 °C was also related to various weld bead characteristics (e.g., total nugget area, heat transfer boundary lengths, bead width-to-depth ratio, and nugget parameter). The bead reinforcement, bead width, penetration depth, HAZ size, deposition area and penetration area increased with increasing heat input, but the bead contact angle decreased with it. The electrode melting efficiency increased initially and then decreased with increasing heat input, but the plate melting efficiency and percentage dilution changed only slightly with it. Cooling time exhibited a very good linear relationship with the total nugget area, heat transfer boundary length, and nugget parameter.     

Sensitivity model for prediction of bead geometry in underwater wet flux cored arc welding

To investigate influence of welding parameters on weld bead geometry in underwater wet flux cored arc welding (FCAW), orthogonal experiments of underwater wet FCAW were conducted in the hyperbaric chamber at water depth from 0.2 m to 60 m and mathematical models were developed by multiple curvilinear regression method from the experimental data. Sensitivity analysis was then performed to predict the bead geometry and evaluate the influence of welding parameters. The results reveal that water depth has a greater influence on bead geometry than other welding parameters when welding at a water depth less than 10 m. At a water depth deeper than 10 m, a change in travel speed affects the bead geometry more strongly than other welding parameters.     

Molten pool behavior in the tandem submerged arc welding process

A three-dimensional numerical heat transfer and fluid flow model is developed to examine the temperature profiles, velocity fields, weld pool shape and size in a two-wire tandem submerged arc welding process. The model solves the equations of the conservation of mass, momentum, and energy along with the volume of fluid method. The volume of fluid method is used to track the shape of the free surface. Further, a novel scheme is proposed to handle the arc interaction and its influence on the molten droplet transfer direction. Using the computational fluid dynamics simulations, it is found that the droplet movement and arc forces from the leading electrode heavily affect the molten pool flow patterns and the resultant bead shapes, even though the same heat inputs are applied. The computed weld width and penetration are in fair agreement with the corresponding experimental results.     

多丝埋弧焊工艺条件对热源参数的影响

为获得多丝埋弧焊的不同电流、电压情况下的热源模型参数,对双椭球热源模型进行了改写.采用有限元的方法,考虑了双丝焊的电弧偏转,对多丝埋弧焊的温度场与热循环进行了计算.结合有限元模拟结果和试验测量结果,通过模式搜索法对不同工艺参数条件下的双椭球模型参数进行了反演计算,获得了双椭球热源模型参数的变化规律.对特定工艺情况以及三...     

单电源双丝埋弧自动焊研究

单电源双丝埋弧自动焊是一种高熔敷速率、高焊接速度、低热输入的埋孤焊方法.通过改变焊丝排列方式和丝间距,其焊缝成形、熔深/熔宽、稀释率可得到更充分的调节.既可适用于稀释率要求较低的耐磨或耐腐蚀表面的埋弧堆焊,亦可适用于各种对接、角接焊缝的单道或多道高速埋孤焊.简述了这种焊机的结构要点,指出了电源及送丝系统的合理配置要求.     

多层多道埋弧焊工艺参数优化设计方法

多层多道埋弧焊应用领域广泛,但是由于焊接参数较多,焊接工艺的制定和参数优化较为困难。首先给出了底层焊(打底焊)、填充焊和盖面焊的焊接参数设定和优化的基本原则,然后设计了相应的参数设定和优化软件,对焊接电流、焊接速度、焊接电压、热输入以及焊道数等基本参数进行优化计算。对所设计的焊接参数优化系统,采用K型坡口的工件进行实验验证,实验结果和本焊接参数优化系统给出的结果符合良好。利用该系统还可以实现填充焊阶段的电流递增优化设计,在保证焊接热输入不超标的情况下,减少焊道数,提高生产效率。     

Effects of ultrasonic pulsation of the welding current on the geometry of the fusion zone and heat-affected zone in submerged arc welding

This paper proposes investigation of an arc ultrasonic excitation technique in the SAW process in order to evaluate the main parameters’ influence associated with pulsed current on weld beads, such as the frequency and amplitude of ultrasonic excitation current. Therefore, an experimental bench was assembled, which consists of two power sources: a conventional welding source and another able to provide pulse current at ultrasonic frequencies. During the tests two ultrasonic excitation current amplitudes were employed, 25 A and 50 A, each one in three different pulse frequencies, 20, 50 and 80 kHz. Macrographs of these welds are observed, and width, penetration, molten area and heat-affected zone area (HAZ) are measured. As a result, contrary to information available in the literature, there were no significant changes in weld bead geometry, as well as in the HAZ, that could be attributed to the current excitation in studied frequencies.     

埋弧焊过程的单片机控制技术及其应用

研制开发出一种单片机控制的新型IGBT逆变埋弧自动焊机。对该焊机的主电源结构、小车行走控制电路、送丝电路、单片机控制电路以及焊接过程控制软件等的设计作了较详细的介绍。     

Analysis of submerged arc welding process by three-dimensional computational fluid dynamics simulations

The effect of torch angle and current polarities on the convection heat transfer in single wire submerged arc welding is analyzed. To develop arc models such as arc heat flux, arc pressure and electromagnetic force, this study adopts the Abel inversion method with CCD camera images for direct and alternating current polarities. The heat transfer by molten slag from the flux consumption is considered as an additional boundary heat source in the numerical simulation. The variation of arc forces, the direction of droplet flight with polarity and the torch angle significantly affect the molten pool flow and the resultant weld beads. The simulated weld pool profiles are validated with corresponding experimental results and found to be in good agreement.     

弧焊过程电信号的频谱分析

傅立叶变换是一种电信号频谱分析的有效算法，设计了一种基于快速傅主叶变换的频谱分析的仿真算例，半验证了此算法的正确性和可靠性。在此基础上采用正交法进行焊接试验方案的设计。通过时CO2焊过程电信号的频谱分析表明：频谱分析法可以有效地提取焊接过程的频率成分，从而据此检验焊接过程的稳定性，为焊接过程的测试和评估提供了一种新的思路。     

脉冲埋弧焊动态过程仿真模型的建立

针对变速送丝调节系统脉冲埋弧焊的特点,利用MATLAB／SIMULINK软件对其动态过程进行了研究,建立了主电路仿真模型、电弧负载系统仿真模型及弧长变化系统仿真模型,并在此基础上形成了系统的整体仿真模型。仿真结果与实测波形吻合良好,证明了所建模型的正确性,并为脉冲埋弧焊的推广应用奠定了基础。     

统计过程控制理论在埋弧焊中的应用

基于Microsoft Visual C 6．0,设计了埋弧焊过程焊接电流和电弧电压的采集、统计分析、显示和保存的软件系统;系统采用统计过程控制理论对埋弧焊接电流、电弧电压和热输入进行统计分析。结果表明,当埋弧焊接过程出现异常时,系统能及时提取反映埋弧焊接过程稳定性的统计信息。     

自动埋弧焊接过程的电弧控制方程与热学分析

埋弧焊系统由恒流特性逆变焊接电源、送丝机、行走小车和控制器组成.控制器的输入是电弧电压Uarc和设置电压Uset,控制器的输出是PWM方式调节DC电源,驱动并调节送丝速度.用一阶微分方程建立了埋弧焊接过程中焊丝送进速度与焊接电弧之间的数学模型,模型描述了埋弧焊接过程中焊丝一边在电弧中燃烧,一边由送丝机不断送到燃弧区的平衡关系.通过电源、熔池、焊丝的热平衡分析,得到焊接系统的焊丝选取方法,该方法是焊丝直径与焊接电流的平方根成正比,文中还给出了焊丝直径与焊接电流的定量选取公式.     

振动埋弧焊工艺

振动埋弧焊工艺是一种在焊接过程中通过给焊件施加振动来改善焊接性能的新工艺.介绍了在西气东输阀门焊接中运用振动埋弧焊进行厚板焊接的试验,就残余应力、焊接变形、金相三个方面对常规埋弧焊和振动埋弧焊工艺进行比较,对振动埋弧焊工艺进行初步探讨.试验结果表明,振动埋弧焊工艺能有效地降低焊接残余应力和变形,并细化晶粒.     

DY-30埋弧焊熔炼焊剂的绿色制造技术

云南奥云焊材科技有限公司研制的DY-30新型自动埋弧焊熔炼焊剂采用创新生产工艺,实现了绿色化和资源循环利用。该焊剂焊接工艺性能优良,提高了熔敷金属的洁净度和低温冲击韧性,并且在生产和使用焊剂的过程中,排放的焊接烟尘总量均低于国际标准和国家标准。较大地改变了传统熔炼焊剂制造过程中存在的资源耗费大、成本高、污染严重等三大问题,走出了熔炼焊剂制造的绿色化和资源循环利用的新路。     

弧偏吹对埋弧焊接质量的影响和焊接工艺改进措施

为避免埋弧焊接过程中产生未熔合、未焊透和条状夹渣等危害性缺陷。提高埋弧焊接质量。探讨了直流弧焊电源埋弧焊接时弧偏吹现象的产生机理．分析阐述了埋弧焊接过程中条状缺陷的形成原因、弧偏吹产生的条件及弧偏吹对埋弧焊接质量的影响，并以此为指导。改进对接焊缝和熔透T形焊缝的埋弧焊接工艺。经推广应用．效果理想，经济效益显著。     

Analysis of keyhole geometry in plasma arc welding

The key problem for numerical simulation of plasma arc welding （PAW） process is to develop a suitable and adaptive volumetric heat source mode which reflects the physical characteristics of keyhole PAW. To this end, the keyhole geometry under different PAW process conditions must be predicted. In this paper, a mathematical model for determining the keyhole shape is developed with considering the mass and momentum conservation of the in-keyhole plasma jet as well as the pressure equilibrium at the plasma jet/liquid metal boundary. A suitable heat source model related to the keyhole shape is applied to the calculation of PAW weld dimensions. The predicted results are in good agreement with the experimental ones.     

耦合电弧钨极GPCA-TIG焊工艺

将耦合电弧钨极和GPCA焊方法结合,形成了耦合电弧钨极GPCA-TIG焊方法,该方法可实现深熔深高速度焊接.对比分析了在较高焊接速度时常规TIG焊、耦合电弧钨极TIG焊和耦合电弧钨极GPCA-TIG焊的焊缝表面成形和截面形貌,发现耦合电弧钨极GPCA-TIG焊可避免咬边和驼峰焊道的产生,并且焊缝熔深有所增加.耦合电弧钨极GPCA-TIG焊工艺试验表明,焊缝熔深和熔宽随焊接速度的减小和外喷嘴位置的升高而增大,随着弧长和外层氧气流量的增加先增加后略有减小;随着焊接速度的减小,弧长和外层氧气流量的增大,焊缝咬边减轻,外喷嘴相对高度变化时焊缝均未出现咬边.