脉冲MIG焊机智能化控制及在铝合金焊接上应用

通过对脉冲MIG电弧的分析,在全数字焊接电源上采用新型＂HyperDip-脉冲＂智能化控制技术,实现了铝合金焊接熔池稳定、熔深增加、气孔缺陷减少的焊接效果。焊接电源融合型机器人＂TAWERS＂和全软件控制的交直流两用MIG焊接技术,实现了铝合金更加完善的自动化焊接质量。     

大厚度紫铜电子束焊接的研究

通过对大熔深电子束紫铜焊缝的研究，采用横枪电子束焊接方法在含气量较高的试件上获得２５ｍｍ熔深的焊缝，并消除了气孔、裂纹等缺陷。讨论电子束倾斜入射工件时，倾斜角度对焊缝质量的影响。     

铝及铝合金激光焊接特性

概述了以激光为热源的铝及铝合金激光焊接技术特性.包括铝及铝合金激光焊接稳定性的影响因素和激光焊接缺陷(气孔、裂纹、焊缝不规则等)及改进措施,并介绍了铝及铝合金激光-电弧复合焊接方法和双光束激光焊接方法.     

铝合金MIG+激光复合焊接工艺研究

研究轻量化轿车用3A21铝合金M IG 激光复合焊接工艺,探讨工艺参数对焊缝成型的影响规律及激光与电弧的复合作用。试验结果表明,采用M IG 激光复合焊接工艺可以显著提高熔深和焊速,达到采用小功率激光焊机实现铝合金的激光焊接。在比较宽的工艺参数范围内M IG YAG激光复合焊接铝合金具有焊缝成型美观等优点,熔深和焊速均显著提高,大大提高生产率。     

基于铝合金激光深熔焊接温度场研究

采用透过玻璃在线拍摄铝合金激光深熔焊接时小孔形状的方法,得到小孔形状的真实尺寸.随后建立铝和玻璃异种材料激光焊接温度场的数学模型,运用数值模拟法分析了激光深熔焊接铝合金与玻璃的温度场分布,在编制Matlab程序计算时用已观测到的小孔半径数值为基础,保证了数值模拟结果的合理性与正确性,得到了不同材料焊接温度场计算的一般方法.     

铝合金激光焊接的研究现状和发展趋势

综述了铝合金激光焊接的特点及难点，分析了铝合金焊接中诸如小孔的诱导和稳定，气孔及热裂纹等问题及其解决方法，介绍了铝合金激光焊接的新方法和新进展。     

变速器结合齿圈激光焊接技术的应用

对变速器结合齿圈激光深熔焊接新工艺进行研究，并做一系列工艺探索试验和产品验证试验，并以此为基础开展激光深熔焊接工艺运用，按照工艺流程进行设备设施策划，并在公司建立两条激光深熔焊接生产线。     

铁道车辆铝合金车体电阻点焊缺陷分析及预防措施

介绍了电阻点焊的基本原理及铁道车辆用A5083、A6N01、A7N01等铝合金材料的焊接特性和点焊工艺。分析了气孔、熔核偏移、熔核不足、飞溅、电极粘附、表面凹坑等常见焊接缺陷产生的原因。针对具体情况,从控制焊接电流、电极形状、压力、许用间隙和焊前清理等方面,制定了铝合金电阻点焊缺陷的预防措施。     

YAG激光与GTAW复合焊接铝合金

研究了YAG激光、GTAW电弧复合焊接铝合金时各种规范参数对焊缝成型的影响规律 ,探讨激光与电弧的复合作用机理。结果表明 ,采用YAG激光 +GTAW复合工艺焊接铝合金具有焊缝成型美观、热影响区小等优点 ,与GTAW焊接相比 ,焊速显著提高 ,可以显著增加熔深 ,达到采用小功率激光焊机实现铝合金的焊接目的 ,Laser、GTAW是铝合金焊接理想的工艺方法。     

浅析船用铝合金焊接及缺陷控制措施

铝合金材料因兼具密度小、强度高、耐腐蚀性强、塑性好等特点，被广泛应用于船舶制造领域。但是铝合金容易氧化，且线膨胀系数大，导致铝合金焊接性比碳钢差，船体焊接时容易出现裂纹、气孔和变形等缺陷。因此，研究船用铝合金种类、焊接缺陷、产生原因及控制措施，具有重要的现实意义。本文从铝合金性能浅析入手，对铝合金常见焊接方法、缺陷及预防措施进行分析，以期为舰船建造和维修提供参考。     

新型柔性变极性等离子弧铝合金横焊技术研究

针对中厚板铝合金横向焊接的技术需求和瓶颈问题,开展变极性等离子弧穿孔横焊技术的研究。以8 mm厚铝合金板为研究对象,进行常规变极性等离子弧穿孔横焊试验,发现横焊穿孔熔池很难建立。通过横焊穿孔熔池受力计算、熔化金属流动分析,探究问题产生的原因。推导出熔池背面小孔临界半径与表面张力、电弧力和重力之间的关系式。当受力状态满足关系式时,小孔熔池才能闭合、形成焊缝。依据上述理论,提出柔性变极性等离子弧。该电弧在保证穿孔前提下,通过降低电弧压力,增大小孔临界半径,促进了穿孔熔池的稳定建立。利用该技术实现了8 mm板厚2219铝合金的穿孔横向焊接,接头成形优良。焊前预热和表面氧化膜刮削可大幅度降低横焊接头气孔缺陷。     

低功率脉冲激光-电弧复合热源高效焊接过程中的“匙孔”行为研究

激光-电弧复合热源焊接技术由于具有焊接熔深大、效率高、质量好等优点而受到广泛关注。采用低功率脉冲激光-钨极惰性气体保护(Tungsten inert gas,TIG)焊电弧复合热源技术进行镁合金板材的焊接,研究激光脉冲作用消失之后的等离子体行为和激光"匙孔"行为。在上述试验结果的指导下优化工艺参数,对比研究采用单独激光焊、TIG电弧焊和复合热源焊这三种方法实现镁合金板材对接焊相同效果时焊接效率的差异。研究结果表明,激光"匙孔"和"匙孔"等离子体的形成是实现复合热源高效焊接的前提条件,恰当的工艺参数可以使得激光"匙孔"维持稳定的开口状态,这种状态提高了电弧的稳定性和能量密度,延长了镁等离子体的恢复时间,因此能够提高复合热源的焊接效率。达到相同焊接效果时复合热源的焊接效率分别达到单独激光焊接效率的7.14倍和单独TIG电弧焊接效率的4.29倍。     

Porosity in fiber laser formation of 5A06 aluminum alloy

The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet’s susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible.     

激光入射角影响焊接熔池匙孔瞬态行为数值模拟

在激光焊接中,激光入射角直接影响着熔池匙孔瞬态行为,而仅采用工艺试验方法难以探索其规律。利用数值模拟技术模拟激光入射角分别为30°、0°、-30°的焊接过程,研究激光入射角对熔池匙孔瞬态行为的影响。同时通过激光焊接试验对仿真结果进行验证,数值仿真的焊缝横截面形貌与试验结果吻合较好,表明仿真结果能够反映激光焊接过程。分析不同激光入射角下温度场、熔池内流场、匙孔后壁反冲压力、匙孔深度和匙孔后壁静压力的变化。结果表明,激光入射角的正负影响熔池内部流动的快慢;激光入射角为正时,有利于抑制飞溅形成,而激光入射角为负时,则促进飞溅生成;激光入射角的正负明显影响匙孔的稳定性,当激光入射角为负时,匙孔稳定性降低,坍塌频率增加,产生气泡的概率提高。使用合适的激光正入射角有利于提高激光焊接质量。     

Butt autogenous laser welding of AA 2024 aluminium alloy thin sheets with a Yb:YAG disk laser

Higher productivity, lower distortion and better penetration are the main advantages provided by laser welding in comparison with conventional processes. A Trumpf TruDisk 2002 Yb:YAG disk laser is used in this work to increases productivity and quality. Aluminium alloys lead to many technological issues in laser welding, resulting in shallow penetration and defects. In particular, AA 2024 aluminium alloy in a thin sheet is investigated in this paper, being it is used extensively in the automotive and aerospace industries. Bead-on-plate and butt autogenous laser welding tests with continuous wave emission on 1.25 mm thick AA 2024 aluminium alloy sheets were examined morphologically and micro-structurally. The geometric and mechanical features of the welding bead were evaluated via a three-level experimental plan. In addition to the power and speed which are traditionally referred to, beam defocusing was considered as an additional governing factor in a central composite design scheme because it massively affects keyhole conditions. Softening in the fused zone is discussed via Vickers micro-hardness testing and magnesium loss through energy dispersive spectrometry. After properly performing the modelling and optimisation of the fused zone and the cross-section shape factor as the response variables, the laser welding conditions for thin sheets of AA 2024 aluminium alloy are suggested. X-ray and tensile tests were conducted on the specimens obtained with the recommended processing parameters to characterise the AA 2024 disk laser welded beads.     

CHARACTERISTICS OF DROPLET TRANSFER IN CO2 LASER-MIG HYBRID WELDING WITH SHORT-CIRCUITING MODE

LF6 aluminum alloy plates with 4.5 mm thickness are welded in this experiment.Welding is carried out by using the CO2 laser-MIG paraxial hybrid welding in flat position. The experimental results indicate that the inherent droplet transfer cycle time of conventional MIG arc is changed due to the interaction between CO2 laser beam and MIG arc in the short-circuiting mode of laser-MIG hybrid welding. Because of the preheating action of CO2 laser to electrode and base material, the droplet transfer frequency of MIG arc is increased in the hybrid welding process. When laser power is increased to a certain degree, the droplet transfer frequency is decreased due to the effect of laser-induced keyhole. Furthermore, through analyzing the MIG welding current and arc voltage waveforms and the characteristics of droplet transfer in the hybrid welding process, the effect of laser energy and the action point between laser beam and arc on the frequency of droplet transfer and weld appearance is investigated in details.     

搅拌摩擦点焊技术在汽车行业的应用

随着汽车行业产品的轻量化发展,镁、铝等轻质合金被大量运用,其焊接技术亦为越来越多的工业制造商所关注,搅拌摩擦点焊技术是在搅拌摩擦焊技术的基础上衍生而来的一种适用于轻金属合金连接的新型的固相点焊技术。可以代替熔焊、激光焊、电阻点焊等多种焊接方法,而成为一种新型的搅拌摩擦焊方法。本文将对搅拌摩擦点焊的产生背景、基本原理以及在汽车行业的应用进行简述。     

Effect of gap on plasma and molten pool dynamics during laser lap welding for T-joints

The aim of the present research is to discuss the effect of gap on plasma plume, keyhole, and molten pool dynamics during laser lap welding for T-joints. The authors observe plasma plume, keyhole opening, and molten pool images by high-speed camera in different gaps during CO₂ laser overlap welding of T-joints. The results show that gap causes beam energy fluctuations in the keyhole and leads to the instability of welding process. In laser spot welding, zero-gap and small gap greatly affect the stability of plasma and keyhole, which causes the formation of cavities in the weld metal, while a proper gap can help prevent porosity formation. In laser continuous welding, the disruption and closure of front keyhole wall at the gap periodically changes with the gap, which causes the formation of plenty of porosities at the gap. The instability of keyhole is closely related to dynamics of plume and molten pool, which gives an insight into the mechanism of porosity formation during laser overlap welding.     

高氮钢激光-电弧复合焊接气孔控制方法研究*

为了掌握高氮钢复合焊接气孔控制的有效方法,研究电弧能量、激光能量和振动频率对焊缝气孔的影响。从气孔率方面分析焊缝气孔的产生原因,并从电流和电压波形及熔滴过渡方面分析其对焊接过程稳定性的影响。熔池流动与焊缝气孔具有一定的关联性,并从熔池流动状态方面分析其对气孔的影响。激光匙孔的形成需要一定的阈值能量,匙孔穿透状态对气孔率有直接影响,依据激光匙孔底部受力情况,分析匙孔状态对焊缝气孔率的影响。结果表明：气孔率随电弧能量或激光能量的增加而呈先升后降的变化趋势,电弧能量4 800 J(I=200 A,U=24 V)时,气孔率最低,仅为0.49%;而激光功率为2.8 kW时,气孔率降为最低,仅为0.14%;施加振动后焊缝气孔率均明显减小,气孔率随着振动频率的增加而先降后升。适当的电弧能量或激光能量可有效抑制焊缝内气孔数量,振动频率为35 Hz时抑制气孔效果最好。     

Adaptive volumetric heat source models for laser beam and laser + pulsed GMAW hybrid welding processes

Laser + pulsed gas metal arc welding (GMAW) hybrid welding process is an attractive joining technology in industry due to its synergy of the two processes. It is of great significance to conduct fundamental investigations involving mathematical modeling and understanding of the hybrid welding process. In this study, an adaptive heat source model is first developed for laser beam welding. Through combining the ray-tracing method with the keyhole profile determination technique based on the local energy balance, the keyhole shape and size are calculated and correlated to the distribution parameters of the volumetric heat source model. Then, thermal action characteristics in laser + pulsed GMAW hybrid welding are considered from viewpoint of macro-heat transfer, and a combined volumetric heat source model for hybrid welding is developed to take consideration of heat input from laser, pulsed gas metal arc, and overheated droplets. Numerical analysis of thermal conduction in hybrid welding is conducted. The shape and size of fusion zone and weld dimension in the quasi-steady state are calculated for various hybrid welding conditions, which have a fair agreement with the experimental results.