We conduct a systematic study about the welding process characteristics of the PMIG and the miniwatt-SCT-MIG of the laminose aluminum alloy as well as how the laser influences these two welding methods. The material used is 6061 aluminum alloy at a thickness of 3mm. The method is to observe the globular transfer process, the arc’s behavior and the characteristics of the welding electric signal during the welding process, and then record the data as well as doing the research.

The research results show that:

Adding the laser shortens the time of arc strike, and improves the stability of the arc strike stage. The Laser-Arc hybrid welding substantially optimizes the arc’s stability, for the laser attracts the arc, making the cathode spot fixed at the laser spot, which improves the stability of the burning arc; The interaction between the arc plasmas and the photoinduced laser plasmas set up an electric channel with high stability at the arc space; These two plasmas’ relative strength decides the distribution of the plasmas: When the laser plasmas are weak, the plasmas mainly distribute in the arc space at bottom of the welding stick. On the contrary, when the arc plasmas are weak, the plasmas mainly distribute in the laser spot area.

Adding laser does influence the globular transfer process of the laminose aluminum alloy’s MIG welding. When the laser power is under a critical value, the globular transfer appears stable; when the laser power is beyond the critical value, the globular transfer appears unstable. The Laser-Arc gap must be in an appropriate range. Being too near or too far both make the globular transfer unstable. According to the correlation theory of mathematical statistics, we developed a set of program to judge the stability of the welding process and made a judgment quantificationally: As for the aluminum alloy, the welding process of Laser- short circuiting transfer MIG welding is more stable than that of simple short circuiting transfer MIG welding.

The PMIG welding of the aluminum alloy has three transition modes: pulse meso-spray transfer, pulse short circuiting transfer, pulse projected transfer. Adding laser has some influences in them. Increasing the laser power helps the pulse meso-spray transfer gradually transform into the pulse projected transfer. When the power reaches a value, the transformation completes. And the adding laser increases the arc length of the projected transfer, making the fusion speed up.

Compared to the miniwatt- MIG welding and the simple laser welding, the Laser-MIG hybrid welding used in the aluminum alloy welding acquires better appearance of weld and deeper weld penetration. In addition, under the condition of the same thermal input by the three welding methods above, the Laser-MIG hybrid welding shows a better welding efficiency.    

Keywords: Laser-MIG hybrid welding; aluminum alloy; globular transfer; short circuiting transfer; pulse welding

目录

第一章绪论 1

1.1研究背景 1

1.2研究现状及其应用 2

1.3研究内容 3

第二章试验材料、设备及方法 4

2.1试验材料 4

2.2信息采集系统与试验平台 4

2.2.1焊接系统平台搭建 5

2.2.2等离子行为与熔滴过渡过程的高速摄像采集系统 6

2.2.3焊接电弧电信号采集系统 7

2.2.4信息同步采集系统工作原理 9

2.3金相组织观察 9

2.4本章小结 9

第三章铝合金短路过渡MIG焊工艺特性 10

及激光对其的影响 10

3.1铝合金短路过渡MIG焊焊接工艺试验 10

3.1.1铝合金短路过渡MIG焊接试验参数 10

3.1.2铝合金短路过渡MIG焊熔滴过渡过程与焊接电信号 11

3.1.3铝合金短路MIG焊焊缝横截面形貌 12

3.2激光对铝合金短路过渡MIG焊的影响 13

3.2.1铝合金激光-短路过渡MIG复合焊接试验参数 13

3.2.2激光的加入对引弧阶段的影响 14

3.2.3激光对焊接过程中电弧形态与电弧稳定性的影响 15