激光焊接工艺的现状与进展

激光焊接作为一种高质量、高精度、低变形、高效率和高速度的焊接方法,在工业中的应用越来越广泛.为了对激光焊接技术进行回顾和展望,概括介绍了常用激光焊接设备及新型二极管泵浦固体激光设备的特性,激光焊接的机理,常用材料激光焊接工艺及其存在的问题,各种改善焊缝质量的工艺,塑料的激光焊接及其数学建模,以及大型激光焊接平台和双光束激光焊接技术的特点,并对国际上激光焊接技术发展的动向作出展望.     

国内外激光焊接现状

1 激光焊接及其特点激光焊接是一种发展很快的焊接新工艺,当10~8～10~(13)W/cm~2的激光束照射到金属表面时,足以使任何金属熔化。而金属在激光的作用下熔接时,材料内部的杂质在高温下汽化,使金属熔池得到净化,从而使焊缝的机械性能高于母材,这在提高焊接质量方面是一个突破。激光焊接可分为连续激光焊接和脉冲激光     

钛合金激光穿透焊的焊缝成形（I）

在对钛合金激光穿透焊焊缝成形特征分析的基础上研究了激光焊主要工艺参数对焊缝成形的影响，同时对比研究了CO2激光和YAG激光穿透焊时焊缝成形的差异。研究结果表明，在穿透焊条件下，CO2激光和YAG激光焊接钛合金焊缝都具有钉形和近X形两种典型的截面形貌。焊缝成形与焊接热输入及激光功率密度有密切联系。随焊接热输入和激光功率密度的增大，焊缝截面由钉形向近X形转变。在采用同样工艺规范获得近X形焊缝成形时，YAG激光焊缝的对称度显著高于CO2激光焊缝。通过调整激光功率、焊接速度和离焦量等激光焊工艺参数，可以对焊缝成形进行有效控制，提高焊接接头质量。     

活塞环槽激光处理工艺优化

总结了该厂多年激光表面硬化处理经验.认为激光淬火和激光熔凝都能硬化球铁和中碳合金钢材料的活塞环槽表面,但从现有工艺性、质量和成本综合考虑,认为激光淬火适合于中碳合金钢活塞,激光熔凝则更适合于球铁活塞.对于进行这两种激光处理前后的机加工工艺也完成了相应优化.     

钛合金激光焊接接头质量控制工艺的研究现状

概要介绍了钛合金激光焊接工艺的研究现状,分析了钛合金激光焊接的工艺特点和激光焊接接头质量的影响因素,阐述了控制钛合金激光焊接接头质量的方案及其发展趋势.     

Nd:YAG激光器金属零件激光快速成型工艺研究

利用Nd：YAG1.1kW激光器和同轴送粉方式进行了金属零件激光快速成型工艺实验研究，叙述了激光快速成型制造系统的基本组成和实验方法；分析了主要工艺参数如：激光功率、扫描速度送粉量以及Z轴增量对成型质量和形貌的影响。给出了在最佳工艺参效下得到的激光成型实例。     

光纤激光切割厚碳钢板小孔的工艺研究

本文以FL513i型数控激光切割机为平台,研究了高功率光纤激光切割机在切割厚碳钢板小圆孔时的切割工艺,通过对工艺参数的调整,研究了光纤激光功率、切割速度、氧气压力、焦点位置对切割质量的影响,总结出优质切割厚碳钢板小孔的工艺参数组合,解决了光纤切割厚碳钢板质量差的问题,从而使光纤激光在切割厚碳钢板中的应用更为广泛。     

自动流量平衡阀阀芯的激光加工工艺研究

通过对自动流量平衡阀阀芯的激光切割和淬火试验,探讨了其加工的工艺特点,分析了等激光功率、扫描速度、切割速度、光斑直径等对加工质量的影响,给出了Nd:YAG激光器加工阀芯的具体方法.实验结果表明,只要工艺参数选择适当,就可获得很好的切割和淬火质量,对实际加工具有一定的指导意义.     

汽车发动机双质量飞轮激光焊接机及其工艺研究

对汽车发动机双质量飞轮激光焊接机及其工艺进行了研究,取得了最佳焊接工艺参数,讨论并分析了各工艺参数及其它因素对激光焊接质量、性能的影响。     

汽车发动机双质量飞轮激光焊接机及其工艺研究

对汽车发动机双质量飞轮激光焊接机及其工艺进行了研究，取得了最佳焊接工艺参数，讨论并分析了各工艺参数及其它因素对激光焊接质量、性能的影响。     

Monitoring laser cut quality using acoustic emission

The paper presents results of an analysis of acoustic-emission (AE) signals obtained during laser cutting of a steel plates, which are frequently used in the production of automotive body components. In the course of laser cutting, continuous signals, which are related to the quality achieved of the laser cut, are measured. After laser cutting characteristic AE bursts in the specimen material, which are results of a thermal influence, can be detected. The presence of dross is an important indicator of poor quality of laser cutting. The investigation on laser cutting was conducted on an unalloyed steel DC04 sheet and on austenitic stainless steel X5CrNi18-10 sheet of 1.5 mm in thickness. The same physical mechanism in the cut formation at both steels, however, resulted in a considerable different cut quality, which was indicated by the AE signals captured after the cutting process.     

激光能量和辅助气体对切割能力影响的数值模拟

采用旋转高斯激光体热源和氧气流量控制的氧铁燃烧反应放热复合热源,基于计算流体力学建立了能够反映激光切割中激光能量、辅助气体和切缝之间相互作用的多相流模型.利用该模型对以氧气和氮气为辅助气体的激光切割过程进行了数值模拟,通过改变激光功率和辅助气体压力,研究了热输入和辅助气体流场对激光切割能力的影响,并对两种辅助气体的切割结果进行了比较和分析.结果表明,所采用的计算模型较好地模拟出激光功率和辅助气体对激光切割能力的影响,并对切缝形状进行预测.     

激光切割加工中CAPP系统的设计与研究

介绍了一种激光切割加工中CAPP系统工艺数据库设计与开发，该系统可以提供激光切割加工的各种加工方法和工艺参数的选择，实现激光切割工艺标准化，并为智能化工艺设计提供了基础。     

激光切割过程辅助气体动力学性能的数值模拟

激光切割过程中辅助气体的动力学性能对切缝形成过程具有重要影响.利用VOF算法和深度自适应激光热源,建立了能反映切割过程中辅助气体和切缝之间相互作用的多相流模型,结合切割试验对模型的有效性进行了验证.采用多相流模型分析了从打孔到稳定切割过程中切缝形貌、辅助气体动力学性能和温度场分布.计算结果表明,在未切透阶段,受切割前沿形状和切割深度等的影响,辅助气体动力学性能不断发生变化;当切割过程稳定后,辅助气体流场几乎不发生变化,切缝形状和温度场也不再改变;所建模型能够有效反映辅助气体动力学性能对切割深度和切缝宽度的影响.     

激光切割不锈钢的工艺研究

通过对不锈钢钢管的激光切割试验,探讨了其加工的工艺特点,分析了激光功率、切割速度、焦点位置以及辅助气体的压力等对切割质量的影响。实验结果表明,只要工艺参数选择适当,可获得很好的切口质量,且能提高生产效率。     

地轨式激光切割机分区除尘装置设计

本文介绍了一种地轨式激光切割机分区除尘装置,可高效抽除切割过程中产生的烟尘,很好地保护激光切割头,大大改善工作环境,提高激光切割机的使用效率。     

CO2 laser cutting of phenolic resin boards

CO₂ laser cutting process of phenolic resin boards has been assessed using a design of experiments (DOE) based methodology. The feasibility and quality of this process is analyzed and compared with the results from laser cutting of particleboard panels. The present work demonstrates that phenolic resin boards can be successfully cut by CO₂ lasers using a laser power of 3 kW at a 3.5 m/min cutting speed.The potential toxicity of the condensed residues formed on the cut edges and the fumes generated during the cutting of the phenolic resin have been also analyzed. CO₂ laser cutting of phenolic resin boards is a feasible process provided special protective measures, here commented, are implemented.     

Al_2O_3陶瓷激光切割工艺研究

为了探究Al_2O_3陶瓷的激光切割工艺特性,采用Nd:YAG激光器对Al_2O_3陶瓷进行加工试验。先通过打孔试验计算获得Al_2O_3陶瓷的激光烧蚀阈值,再通过切割试验分析激光功率、切割速度、脉冲频率、离焦量等工艺参数对切割质量的影响规律。结果表明:通过优化激光切割工艺参数,可在保证切割效率的同时,提高Al_2O_3陶瓷的切割质量。     

50CrV钢螺丝刀刃口的激光淬火工艺优化与组织性能特征

为提高螺丝刀头刃口硬度与耐磨性,延长其使用寿命,在已做激光淬火薄壁件预试验基础上,采用大功率光纤耦合半导体激光器于螺丝刀刃口上进行激光淬火试验。利用光学显微镜、显微硬度计、摩擦磨损试验仪等试验测试仪器,分析刃口激光淬火区域组织形态特征、显微硬度及耐磨损性能,确定螺丝刀刃口激光淬火可行的工艺参数。试验结果表明:激光淬火后刃口由完全淬透区、过渡区、基材3部分组成,完全淬透区显微组织为针状马氏体与残留奥氏体,过渡区由马氏体与回火索氏体组成。刃口激光淬火合理工艺参数为激光功率600 W、扫描速度900 mm/min。激光淬火后刃口截面平均硬度为805.7 HV0.3,相对淬火前提高了177.4 HV0.3,表层硬度值达到816.7 HV0.3,相对淬火前提高了188.4 HV0.3。淬火后刃口表面磨损量为0.5 mg,为基材磨损量的27.8%,稳定摩擦因数为0.25,为基材稳定摩擦因数的65.8%。激光淬火工艺能有效提高螺丝刀刃口的显微硬度与耐磨性,可用于螺丝刀刃口表面性能强化。     

Analysis of heat effects in laser cutting of steels

Efficient control of laser cutting processes is closely related to knowledge of heat effects in the cutting front and its surroundings. Similar to other machining processes using high power densities, in laser cutting processes it is very important to monitor the heating phenomena in the workpiece material due to heat input. In laser cutting processes with oxygen as an auxiliary gas, cutting energy is a combination of laser beam energy and the energy of the exothermic reactions occurring in the cutting front. The presence of oxygen in the process increases cutting efficiency, but also causes additional physical processes in the cutting front that render a more detailed analysis of the cutting phenomena difficult. The aim of this article is to analyze the emission of infrared rays from the cutting front with a photodiode, statistically analyze the temperature signals, and optimize the laser cutting process based on a critical cutting speed. The measured infrared radiation temperature signal was, on the basis of calibration, converted into a temperature that was related to the formation of macro- and microstructures and to the change in microhardness in the surface layer of the cut. On the basis of experimental results, it was proved that heat effects in the cutting front decisively influenced the quality of cut. Finally, factor analysis was used to establish statistical relations among variables of the laser system, variables of the cutting process, and geometrical characteristics of the cut.