双丝旁路耦合电弧高效熔化极气体保护焊双变量解耦控制模拟与试验分析

双丝旁路耦合电弧高效熔化极气体保护焊是一种新型、高效的焊接方法。针对其在开环条件下焊接过程不稳定、焊缝成形差的问题,提出通过旁路送丝速度控制旁路弧长从而保证焊接过程稳定性、通过控制旁路电流调节流经母材电流的双变量解耦控制方案并进行模拟与分析。在此基础上,采用快速原型控制系统,设计双丝旁路耦合电弧高效熔化极气体保护焊试验系统并进行双变量解耦控制焊接试验。结果表明,双丝旁路耦合电弧高效熔化极气体保护焊双变量解耦控制方案可以有效地保证焊接过程与流经母材电流的稳定,与模拟结果基本一致;并且由于采用解耦算法,控制过程稳定性更好、响应速度更快、精度更高,并得到成形良好的焊缝,焊接过程飞溅也较小。     

双丝旁路耦合电弧GMAW高效焊接工艺

在介绍了双丝旁路耦合电弧熔化极气体保护焊(双丝旁路耦合电弧(Double-electrode gas metal arc welding,DE-GMAW))高效焊接工艺原理的基础之上,采用双闭环反馈解耦智能控制系统,进行双丝旁路耦合电弧GMAW高速焊接工艺试验,测量双丝旁路耦合电弧GMAW母材热输入,分析双丝旁路耦合电弧GMAW高效焊接工艺机理,并对双丝旁路耦合电弧GMAW高效焊接工艺方法进行改进,进一步研究混合气体保护下的双丝旁路耦合电弧GMAW及其熔滴过渡行为,且开发出单电源双丝旁路耦合电弧GMAW。研究表明:采用双闭环反馈解耦智能控制系统使双丝旁路耦合电弧GMAW焊接过程稳定性更好、精确度更高且响应速度更快;旁路分流是实现高效焊接的同时降低母材热输入的关键;采用混合气体保护下的双丝旁路耦合电弧GMAW能进一步提高焊接过程稳定性,单电源双丝旁路耦合电弧GMAW能形成良好的焊缝成形,且设备成本低。     

单电源双丝旁路耦合电弧熔化极气体保护焊智能控制研究

提出单电源双丝旁路耦合电弧熔化极气体保护焊方法,采用特定的连接方法独立控制通过焊丝与基材的电流;引用逆向求解算法;搭建用来描述焊接过程中参数变化的数学模型。由于熔化母材的焊接电流易在主路电流和其他焊接条件变化时产生波动,提出利用改变旁路送丝速度调节旁路焊丝的熔化电流,实现控制母材电流的控制方案并进行仿真与试验。试验结果表明:单焊接电源的双丝旁路耦合电弧熔化极气体保护焊能够同时兼顾高熔敷率与基材低热输入的焊接;搭建的数学模型能够描述不同焊接参数的变化;利用提出的智能控制方案及算法,有效地解决了母材焊接电流易波动的问题,达到了焊接过程稳定性的控制,同时得到了成形良好的焊缝。     

脉冲旁路耦合电弧MIG焊的动态数学建模及过程控制

脉冲旁路耦合电弧熔化极惰性气体保护(Metal inert-gas, MIG)焊是一种新型的低热输入焊接方法,它通过特定的接法引入旁路电弧与主路电弧实现热、力的耦合,利用旁路电弧的分流作用,实现熔化母材热量与熔化焊丝热量的独立控制,从而在精确控制母材热输入的同时保证熔滴的自由过渡形式,可以实现铝-钢等异种金属的连接。为了理论分析不同焊接参数对焊接过程的影响,通过等效、线性化处理与迭代数值求解算法,建立可以正确描述焊接物理过程的动态数学解析模型;针对焊接过程中耦合电弧稳定性较差且直接影响焊接质量的问题,提出通过检测弧压波动的反馈信号、实时调节送丝速度、进而控制耦合电弧稳定性的闭环控制方案,并基于快速原型系统进行焊接过程控制仿真与试验。仿真结果表明,当焊接过程受到干扰后,采用闭环控制方案可以显著提高耦合电弧的稳定性;焊接试验证明了控制仿真的预测与分析,进行闭环控制后,焊接过程更加稳定同时得到了成形良好的铝-钢异种金属接头。     

脉冲MIG焊建模仿真分析及弧长控制

针对脉冲MIG焊过程中的电弧稳定性问题,建立基于尖端不稳定熔滴过渡理论的焊丝熔化动态电弧模型,并对焊接过程中的电弧电压、电弧长度及熔滴过渡尺寸进行仿真,得到与实际焊接相似的电弧电压波形,分析脉冲电流下熔滴过渡频率及影响电弧稳定性的因素,且进行弧长稳定控制的仿真研究,在此基础上运用快速原型技术建立铝合金脉冲MIG焊控制系统,采用电弧电压反馈对铝合金脉冲MIG焊过程进行送丝调节的弧长控制试验。研究表明:所建立的铝合金脉冲MIG焊焊丝熔化动态电弧模型很好反映了实际焊接过程,揭示出脉冲MIG焊焊接过程中熔滴过渡时间间隔具有一定的不确定性和电弧长度的不稳定性,通过电弧电压反馈控制可显著改善铝合金脉冲MIG焊过程电弧系统的稳定性。     

双旁路耦合电弧铝合金MIG焊熔滴过渡形态研究

提出双旁路耦合电弧熔化极惰性气体保护(Dual bypass metal inert-gas,DB-MIG)电弧焊方法并建立试验系统.该方法以传统熔化极惰性气体保护焊接电弧为主弧,引入两路对称的电流可控的非熔化极旁路电弧并与主弧形成耦合电弧进行焊接.由于旁路电弧的分流作用,在保持较高焊丝熔化电流的同时可有效降低母材输入电流,并且旁路电弧力的作用对熔滴过渡也有显著的影响.设计专用的窄带滤光系统,实现无激光背光的焊接熔滴过渡行为的高速摄像,获得不同旁路电流参数条件下的铝合金DB-MIG焊熔滴过渡的高速摄影图像并进行分析.试验结果表明总电流恒定的情况下,熔滴过渡形态随旁路电弧电流参数改变而改变.对DB-MIG焊条件下作用于熔滴上的电弧力的分布进行理论分析,解释试验现象,理论分析和研究表明双旁路耦合电弧可以促进熔滴过渡并可显著降低喷射过渡的临界电流.     

脉冲DE-GMAW过程熔滴受力分析及电流波形设计研究

针对为了实现铝-钢高效高质量的连接,提出一种高效低热输入的脉冲旁路耦合电弧熔化极惰性气体保护焊(Double-electrode gas metal arc welding,DE-GMAW)方法。为了使其焊接过程熔滴平稳过渡,分析旁路电弧对熔滴过渡时电流密度的影响,确定脉冲DE-GMAW熔滴过渡时电磁力的作用机制,在主路为脉冲电流情况下,分别设计旁路波形与主路组合形式即为恒定电流、交替脉冲电流和同步脉冲电流三种形式的研究,并使用高速摄像拍摄熔滴过渡图像,进行对比分析试验验证。结果表明,焊接电流波形及组合形式不同会导致作用于焊接熔滴的受力发生改变,从而使得焊接过程的稳定性与焊接质量也发生变化,对比分析得出采用同步脉冲电流时的脉冲旁路耦合电弧熔化极惰性气体保护焊焊接过程稳定、熔滴过渡均匀一致且焊缝成形平整美观。     

高速旋转电弧传感器的数学模型

以气保护焊接系统的数学模型和HALMOY焊丝熔化模型为基础,对高速旋转电弧传感器进行数学建模。利用该数学模型模拟焊接电流、弧长和焊丝伸出长度随时间的变化规律。实际焊接试验显示,模拟焊接电流与实际焊接电流波形高度吻合,说明建立的数学模型是准确的。结果表明,高速旋转电弧焊接时,弧长的变化较焊丝伸出长度的变化更为显著。利用每个电弧旋转周期内左半周与右半周平均电流值的差,可以判断焊枪的偏差量及其方向,同时还可根据平均电流值的大小来检测角接终止点。所建立的模型对于高速旋转电弧传感系统的设计具有指导意义。     

双丝窄间隙熔化极气体保护焊的焊接稳定性

双丝熔化极窄间隙气体保护焊(NG-GMAW)前后焊丝之间沿焊接方向的距离和夹角、焊丝与坡口侧壁之间的距离等参数都可以独立调节,并对焊接过程稳定性有很大影响.试验发现,双丝沿焊接方向的间距小于15 mm或大于50 mm时,双电弧处于共熔池或独立状态,焊接过程稳定:而当双丝间距在20～30 mm时,处于共熔池向独立熔池过渡阶段,受窄间隙坡口中非均衡分布的电磁力作用,频繁出现断弧现象,焊接过程不稳定.双丝沿焊接方向平行竖直分布时,焊接过程稳定,若前丝后倾则会加剧电弧的偏移,焊接稳定性变差.焊丝与侧壁间距对电弧形态有很大影响,当间距为2.5 mm时,电弧在焊丝和坡口底部以及侧壁之间稳定燃烧;而当间距达到1.5 mm时,出现侧壁打弧现象,焊接稳定性恶化.     

激光+双丝脉冲MAG复合焊的焊接稳定性

研究激光和Ar+He混合气体中He气体体积分数对激光+双丝脉冲MAG复合焊焊接稳定性的影响。搭建激光+双丝脉冲熔化极活性气体保护(Metal active-gas, MAG)复合焊焊接系统,利用LabVIEW信号采集系统采集焊接电流和电弧电压波形,借助高速摄像系统同步拍摄电弧形态和熔滴过渡过程,实时监测焊接过程。观察后丝短路和前丝断弧情况并对前丝电弧电压进行单因素方差分析,研究Ar+He混合气体中He气体体积分数对焊接稳定性影响;比较焊接过程中激光的有无对熔滴过渡的影响,分析激光对焊接稳定性影响。结果发现随着He气体体积分数增大,后丝对应短路次数增多,当He气体体积分数为50%时,前丝出现断弧现象,大于50%,断弧时间随之增加,焊接稳定性变差;激光+双丝脉冲MAG复合焊和双丝脉冲MAG复合焊相比,加入激光可稳定电弧,为熔滴提供一附加力,该力促进熔滴过渡,使熔滴过渡尺寸减小,加大过渡频率,改善熔滴过渡,提高焊接稳定性。     

Prevention of humping bead associated with high welding speed by double-electrode gas metal arc welding

Manufacturing productivity can be improved by increasing the welding speed. However, humping bead will occur when welding speed is beyond a certain value. An experimental system of double-electrode gas metal arc welding (DE-GMAW) was developed to implement high speed welding and prevent from humping bead formation. The DE-GMAW appropriately partition the heat energy between the wire and the base metal so that higher deposition rate of filler wire and suitable shape and size of weld pool are ensured. The arc images captured during DE-GMAW process were used to optimize the geometric parameters between the gas tungsten arc welding and the gas metal arc welding (GMAW) torches. The main arc and bypass arc integrated well and satisfactory weld bead formation was obtained. Through observing the weld pool behaviors from side view during DE-GMAW process, it was found that the height of both solidified and molten region at the pool tail is almost flat so that no humping bead was formed during DE-GMAW with the welding speed up to 1.7?m/min. The side view images of weld pool in DE-GMAW were compared with those in conventional GMAW, and the reason why DE-GMAW can suppress humping bead is shortly discussed.     

Evaluation of scatter-search approach for scheduling optimization of flexible manufacturing systems

This paper presents an automatic welding control system for the alternating current shield metal arc welding process. A nominal nonlinear mathematical model containing uncertainties such as dead-zone, welding control system saturation, and the identified system parameters is derived. A novel variable structure model reference control scheme is designed to modulate the rate of the electrode feed mechanism, thereby regulating the arc current. The developed controller assures the global reaching condition of the sliding mode of the controlled welding system. In the sliding mode, the electric current error between the plant and the model asymptotically approaches zero. Moreover, the welding system remains insensitive to uncertainties and disturbance as the systems with friction. The simulation and experimental results confirm that the automatic welding control system, based on the proposed model-following variable structure controller, successfully maintains the magnitude of the arc current at the desired value and preserves the stability of the arc length, thereby ensuring excellent welding performance.     

Adaptive fuzzy sliding mode control for an automatic arc welding system

This paper describes an automatic welding control system developed for alternating current shielded metal arc welding (SMAW). This method could replace manual operations which require a well-trained technician. We have derived a mathematical model of the welding control system and identified the system’s parameters. The sliding surface is used as the input variable to reduce the number of fuzzy reasoning rules, in comparison with the conventional two-dimensional fuzzy logic control (FLC) algorithm. An adaptive fuzzy sliding mode controller (AFSMC) consists of an equivalent control part and a hitting control part. An adaptive law derived from a Lyapunov function is used to obtain the FLC’s parameters, and is applied to approximate the equivalent control part of the sliding mode control (SMC), so that the system states can be forced to zero. By using three-rules FLC, the control part that satisfies the hitting conditions of the SMC can force the system’s states to reach and remain on the sliding surface. Therefore, the stability of the AFSMC can be guaranteed and can be used to modulate the rate of the electrode feeding mechanism that regulates the arc current of the SMAW. The simulation and the experimental results both show that this automatic welding control system, based on the AFSMC, can perform effectively.     

基于正弦摆焊的弧焊机器人焊缝跟踪系统的研究

针对弧焊机器人在焊接过程中示教轨迹和实际焊缝位置存在偏差的问题,提出一种基于正弦摆焊的电弧传感方案。首先规划了弧焊机器人正弦摆焊轨迹,对采集到的焊接电流进行谐波提取来获得焊缝位置的横向偏差,然后根据偏差信息纠正机器人的示教轨迹。把这种方案应用在具有对称坡口的焊缝上进行跟踪,取得了良好的效果。     

Adaptive fuzzy sliding mode control for an automatic arc welding system

This paper describes an automatic welding control system developed for alternating current shielded metal arc welding (SMAW). This method could replace manual operations which require a well-trained technician. We have derived a mathematical model of the welding control system and identified the system’s parameters. The sliding surface is used as the input variable to reduce the number of fuzzy reasoning rules, in comparison with the conventional two-dimensional fuzzy logic control (FLC) algorithm. An adaptive fuzzy sliding mode controller (AFSMC) consists of an equivalent control part and a hitting control part. An adaptive law derived from a Lyapunov function is used to obtain the FLC’s parameters, and is applied to approximate the equivalent control part of the sliding mode control (SMC), so that the system states can be forced to zero. By using three-rules FLC, the control part that satisfies the hitting conditions of the SMC can force the system’s states to reach and remain on the sliding surface. Therefore, the stability of the AFSMC can be guaranteed and can be used to modulate the rate of the electrode feeding mechanism that regulates the arc current of the SMAW. The simulation and the experimental results both show that this automatic welding control system, based on the AFSMC, can perform effectively.     

带状电极窄间隙MAG焊

为解决窄间隙焊接中普遍存在的侧壁和焊缝根部熔合不良的问题,基于减小间隙宽度让电弧直接加热间隙侧壁的思路,提出采用矩形截面的带状电极代替常规的圆形焊丝作为熔化极伸入到间隙中进行焊接,利用特殊形状的带状电极在间隙中自动形成的摆动电弧来改善对间隙侧壁和根部的加热,实现窄间隙焊接。研制专用的焊枪,研究间隙宽度、电弧电压和送带速度对间隙中带极端部电弧行为的影响。试验发现,电弧在间隙中的摆动受间隙宽度、电弧电压和送带速度的影响程度依次降低。间隙宽度对电弧的摆动具有决定性作用,间隙太宽电弧不能摆动;电弧电压过高导致电弧沿侧壁攀升得不到抑制,而送带速度主要与电弧电压搭配,保证焊接过程的稳定性,二者对间隙中电弧的摆动行为影响较小。结果表明,合理匹配间隙宽度、电弧电压和送带速度可以实现稳定的摆动电弧,获得侧壁和焊缝根部熔合良好的窄间隙焊缝。