激光焊接参数对冷作模具钢焊缝表面成形的影响

利用激光焊机在Cr13Mo1Si1V1冷作模具钢表面进行自熔焊接试验,探讨了脉冲激光焊接工艺参数对焊缝横断面形貌尺寸的影响.结果表明:随着激光脉冲能量的增大,焊缝熔深及表面宽度都明显增大;随着脉冲宽度的增大,熔深增长不明显,但表面宽度却明显减小;随着脉冲频率的提高,焊缝熔深及熔宽均减小;加大光斑直径会导致加热区域扩大,熔深减小.采用脉冲激光焊接该模具钢时,脉冲能量和光斑直径对熔深的影响较大;脉冲宽度对表面宽度的影响较明显;脉冲频率对焊缝横断面形貌尺寸的影响相对较小.     

激光摆动焊接工艺参数对不锈钢焊缝成形与气孔率的影响

采用激光摆动焊接实现了5 mm厚1Cr18Ni9Ti不锈钢的焊接,获得成形良好、低气孔率的接头.分析了焊接速度、摆动幅值、摆动频率、摆动形式对焊缝成形和气孔率的影响,从匙孔、熔池流动、气泡逸出的角度揭示了工艺参数影响气孔率的主要机理. 结果表明,对于5 mm厚不锈钢激光摆动焊接,适当提高焊接速度和摆动幅值,更利于减小气孔率;激光摆动频率在100 ~ 300 Hz可以兼顾较低气孔率和较好的焊缝成形;“8”形摆动激光可以获得相对较优的焊缝成形,焊缝气孔率最低,达到2.94%;而线性摆动激光获得焊缝成形最差,气孔率最高,达到19.13%.     

激光焊接声信号与熔深的相关性

激光焊接过程伴随着强烈的声信号,这些声信号中包含焊接过程的重要信息,反映了焊缝质量.以平板激光堆焊为研究对象,详细地分析了焊接过程声信号的特征.研究发现,声信号的强度和功率频谱分布与焊缝熔深具有良好的对应关系.声信号功率频谱主要集中在2～10kHz之间,并且具有明显的谱线族.随焊缝熔深的减小,声信号强度减弱,并且声信号频谱族由相对集中单一向分散多族化变化.以激光焊接过程产生的声信号特征作为传感信息,采用人工神经网络技术建立了声信号与焊缝熔深之间的关系模型.结果表明,该模型能够根据声信号特征定量地检测焊缝的熔深,为激光非熔透焊接熔深的实时检测提供一种有效的手段.     

激光填丝焊焊丝指向与焊缝成形关系的研究

针对首钢酸轧生产线激光焊接头断裂事故,发现焊缝成形存在不稳定缺陷。利用高速摄影手段,研究了焊丝指向对焊缝成形的影响规律。指出:当焊丝指向熔池中光束位置正下方时,焊缝成形最好,熔化焊丝过渡稳定顺畅;当焊丝指向熔池后方时,焊丝在进入熔池前已被全部熔化,熔滴经历产生、长大到滴落的循环,造成焊缝成形不稳定;当焊丝指向熔池前方时,焊丝熔化不够充分,也会造成焊缝成形的不稳定。分析确定,酸轧生产线焊缝成形不稳定现象由焊丝指向熔池后方所致。最终,制定了防止酸轧生产线焊接接头断裂的工艺措施,解决了接头断裂问题,每月为企业减少损失300多万元。     

激光摆动焊接工艺参数对高强钢气孔率和焊缝成形的影响

以10Ni5CrMoV 高强钢钢板为研究对象,开展了激光摆动焊接过程中摆动轨迹、摆动幅度、摆动频率对焊缝成形和气孔率影响的研究。结果表明,几种激光摆动焊接焊缝的气孔率低于激光不摆动焊接,其中,垂直轨迹抑制气孔产生的效果最为显著。在垂直摆动轨迹下,30～90 Hz范围内,随着频率的增加,焊缝熔宽基本不变,焊缝熔深略有增加。当摆动频率在90～150 Hz范围内,随着摆动频率的增加,焊缝熔宽减小,熔深增加。在摆幅为2 mm时,摆动频率在30～60 Hz的低频区间内,焊缝气孔率相对较低,气孔率低于0.15%。     

CO2激光焊接工艺对AZ31B变形镁合金焊缝表面成形的影响

采用3 kW的CO2激光器焊接4 mm厚的AZ31B变形镁合金板材,研究了气体保护方式和焊接工艺参数对焊缝表面成形的影响.试验结果表明,保护气流的方向和气流量对焊缝表面成形存在显著影响,当气流方向与焊接方向相反并与水平方向呈30°角、气流量为2 000 L/h时,焊缝的表面成形最为均匀平整.通过调整激光功率和焊接速度等工艺参数来改变焊接热输入,可以获得"未熔透"、"仅熔池透"、"适度熔透"和"过度熔透"等不同熔透状态和表面成形特点的焊缝,其中"适度熔透"状态的焊缝正、背面成形最均匀;在相同的焊接热输入条件下,强参数规范条件下获得的焊缝表面成形效果最佳.     

5A02铝合金CO2激光焊接工艺与焊缝成形

对5A02铝合金的CO2激光焊接工艺进行试验研究,确定合理的激光焊接工艺参数(焊前准备处理、气体保护、离焦量、焊接热输入等)。针对铝合金对CO2激光吸收率极低,进行了表面预置硅粉焊接,提高了吸收率。2mm厚5A02铝合金板材CO2激光深熔焊的临界功率为1.25kW,熔合区横截面形状为酒杯状。通过试验确定了烛缝成形最理想的激光焊接工艺参数。     

焊接参数对铝合金VPPA焊缝成形的影响

在铝合金变极性等离子弧穿孔立焊过程中,正、反极性电流和离子气流量等焊接参数对焊缝成形和焊缝质量都有显著影响,这些焊接参数的合理匹配是保证穿孔过程和焊缝稳定成形的重要前提.试验采用厚度10 mm的LD10铝合金板作为焊接母材,重点研究了焊接电流和离子气流量对焊缝质量的影响,分析了正、反极性电流的幅值和时间比对焊缝成形的影响规律.研究结果表明:随着焊接电流的增大,焊缝背面熔宽和余高增大,正面熔宽增大而余高减小;随着离子气流量的增大,焊缝背面余高和宽度增加,正面余高和宽度减小.     

Factors controlling the magnesium weld morphology in deep penetration welding by a CO2 laser

In laser welding with power density beyond 10⁴ W · mm⁻², the formation of plasma cavities, commonly referred to as keyholes, leads to deep penetration welds with high aspect ratios. In this paper, the morphologies of keyhole welds produced with a 6 kW CW CO₂ laser on two die-cast magnesium alloys, AZ91 and AM50, are compared. It was found that the two magnesium alloys responded differently to laser welding. Though irregular weld cross-section profiles were consistently observed on each materials, bead dimensions often varied with the welding variables in contrasting ways. For both alloys, important characteristics of the weld beads such as depth, width, crown height (hump), and surface ripples were analyzed as a function of the welding parameters, most particularly the heat input. Results show that the use of heat input, a variable grouping two welding parameters into one, was often inadequate in characterizing the bead morphology. Several explanations are given, including base metal vaporization, but the process of bremsstralung absorption explains it well and rationalizes many observed characteristics of laser weld morphology.     

CO2气保焊机与焊接工艺参数的匹配

购买新焊机需要考虑实际焊接时所用的工艺参数,提高生产效率和降低焊接成本.工程技术人员根据本厂生产现状选用KH600型焊机,兼顾生产效率和成本,优化原有焊接工艺参数,取得了较好效果.     

Visual sensing and morphological image processing of weld pool in laser spot welding

A visual sensing system was established to monitor the weld pool in laser spot welding.The top-hat and bottom-hat transformation algorithms based on mathematical morphology were used to compensate for non-uniform contrast of weld pool edge.Moreover,the canny edge detector was applied to extract the weld pool profile.The edge detected results show that the morphological operation is obviously superior to the traditional contrast enhancement method.In addition,the combination of dilation and erosion was applied to eliminate the irrelevant edge details,and the smooth weld pool edge was acquired.Based on the image processing technology described above,the dynamic process of weld pool diameter during laser spot welding was obtained.     

CO2焊接熔池直接视觉图像传感研究

应用被动式视觉传感方法进行CO2焊焊接熔池的形状检测。为了消除弧光干扰并获得清晰的熔池图像,设计了由窄带滤光片、中性密度滤光片和普通焊接滤光片构成的复合滤光系统。基于CO2焊焊接弧光的光谱分布特征,首先确定了窄带滤光窗口机心波长为632．8nm。然后,通过实验确定了中性密度滤光片和普通焊接滤光片的规格,以及它们与窄带滤光片的最佳组合方式。图像检测实验结果表明,该复合滤光系统有效地消除了弧光干扰,获得了高质量的熔池图像。同时,对CO2焊焊接熔池的图像特征进行了初步分析,为进一步进行熔池图像处理和焊缝成型控制的研究奠定了基础。     

油箱端面环缝CO2焊接工艺

采用新的自动焊接设备、新的焊接工艺,解决了薄板(厚 2 mm 2 mm)、端面(圆角长方形)环缝搭接封头焊的难题.结果表明,薄板冲压件以及装配定位焊带来的环缝搭接间隙和无规律性错边量影响完全消除,获得了高质量焊缝.     

旋转电弧焊接工艺参数与焊缝成形的关系

在旋转电弧自动焊接中工艺参数的选择对焊缝成形有很大的影响,而数学预测模型的建立可以用来选择主要焊接工艺参数。本文简单介绍了回归分析法的原理,并运用回归分析法建立了旋转电弧自动焊接中焊枪旋转频率、旋转半径、焊枪高度和焊接电流与熔宽、熔深之间的预测模型,并对预测模型进行了统计检验与误差分析。最后根据预测模型进行了焊接工艺参数的灵敏度研究。     

Influence of welding parameters on distribution of wire feeding elements in CO2 laser GMA hybrid welding

Abstract

The effect of welding parameters on the distribution of wire feeding elements has been investigated during CO₂ laser and pulsed gas metal arc hybrid welding process. The molten metal flow on the pool surface and inside of the samples was observed by a high speed video camera and an in situ X-ray transmission imaging system respectively. The results indicate that the fluid flow towards the inside of keyhole, namely inward flow, improves the homogeneity of weld metal. The distribution of alloying elements is more homogeneous in leading laser compared with leading arc, since both of the drag force of the plasma jet and momentum of droplet promote the inward flow in leading laser. Almost homogeneous distribution of alloying elements can be attained if the oxygen content in the shielding gas is more than 2%, since the Marangoni flow direction changes from outward to inward with increasing the oxygen content.