【作者】 李晓鹏；

【导师】 张秉刚；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2013， 硕士

【摘要】 本文在研究了电子束填丝焊各个工艺参数对焊接过程的影响的基础上，以CCD视觉传感系统为辅助工具，在自行研发的电子束填丝焊焊接试验平台上，研究了焊丝的熔化机制，以及焊丝填入和送丝速度的变化对熔池和匙孔动态行为的影响。分析结果显示，电子束填丝焊的前置送丝方式比后置送丝方式的工艺过程更稳定，对焊接过程中的波动的适应能力更强，可用工艺范围更宽。在保证喷嘴不被烧毁的情况下，送丝角度越大，焊丝对电子束的遮挡作用越小，产生的熔深越大，而且送丝的指向性越好，更适合于焊接。当束丝作用位置位于区间[-0.7mm，0.9mm]内部时，焊缝表面成形最好。在焊接过程中线能量在区间[240J/mm,450J/mm]内仅是焊缝成形优良的必要条件，要想获得良好的焊缝成形，必须还要同时满足单位体积焊丝对应的能量达到42.45η J/mm3。对于本文采用的工艺参数而言，前置送丝方式，较大的送丝角度，焊接速度为0.30m/min,送丝速度为1.87m/min，束流为25mA时，可以得到最好的焊缝成形。以优化得到的工艺参数对焊丝的熔化机制进行系统的研究，得到在束丝相离、束丝部分相交和束丝完全相交三个不同的束丝作用形式时，不同的送丝速度下，焊丝有五种过渡方式：“直接过渡”，“液桥过渡”，“小滴过渡”，“大滴过渡”和“混合过渡”。其中焊丝以“液桥过渡”形式向熔池中过渡时，焊丝对熔池的干扰作用最小，束、丝和熔池耦合最好，焊接过程最为稳定。此时焊丝填入位置在区间[-0.7mm,0.9mm],送丝速度为1.87m/min。最后对液桥过渡‘过程中的熔池和匙孔的动态行为进行了研究，得到结论：相对于电子束自熔焊，电子束填丝焊的熔池平均面积增加，匙孔平均面积减小，而且两者的波动幅度增加，波动频率减小。随着送丝速度的增加，熔池面积增大，匙孔的平均面积先增加后减小，当送丝速度为1.87m/min时，得到匙孔面积达到最大值。更多还原

【Abstract】 In this paper, the influence of welding process parameters on welding process ofelectron beam welding with filler wire has been study firstly. Then, the meltingdynamics of filler wire and the effects of filler wire on the dynamic behavior of weldingpool and keyhole have been study with the aid of CCD visual sensing system on theself-built test platform.The results showed that front feeding is more stable than rear feeding during EBWwith filler wire. And the front feeding is more easily adapt to the fluctuation during thewelding process. With the increase of wire feeding angle, the blocking effects of wire onelectron beam is waning and the penetration during the welding process is increasing.Meanwhile, the directivity of the feeding wire is better which is more suitable forwelding. A best weld appearance can be obtained when wire beam position located inthe interval of [-0.7mm,0.9mm]. Linear energy locating in interval of [-0.7mm,0.9mm] is a necessary condition for good weld appearance. And only the energy per unitvolume wire reaches42.45ηW/mm3can obtain good weld appearance. Front feedingwith large feeding angle, under the condition of a wire feeding rate of187cm/min, awelding speed of200mm/min, and a welding current of25mA were desirable forachieving optimal weld appearance.A systematic study of the filler wire melting dynamics based on the optimal resultshowed that the filler wire’s melting and transition behaviors can be divided into fivecategories, named as "Direct Transition","Molten Metal Bridge Transition ","SmallDroplet","Big Droplet", and "Mixed Transition". The welding process can be carriedout with high stability and the Beam-Wire-Weld Pool Coupling Model couples best onlywhen the filler wire transits into the welding pool by molten metal bridge.At last, the dynamic behavior of weld pool and keyhole of ’’ Molten Metal BridgeTransition "was studied. The results showed that the weld pool area of EBW with fillerwire increased and the keyhole area decreased relative to EBW without filler wire. Withthe increase of the wire feed rate, the molten pool area increases, the area of the keyholeincreased firstly and then decreases. Meanwhile,the fluctuation margin of welding pooland keyhole increase and the vibration frequency decreases.更多还原