焊接烟羽控制的通风方法

针对气体保护电弧焊的焊接过程分析了焊接烟羽的对流特性和多点分散性、焊点的移动性和非连续性,采用真空吸尘技术、局部排风装置及置换通风方法改善了焊接厂房的空气品质,保证了操作工人的健康安全。

超大焊接厂房自然通风方式模拟与对比研究

针对超大焊接厂房通风防尘风流路线长易导致焊接烟气滞留,严重威胁作业者职业健康的问题,研究最不利自然通风条件下保障厂房环境的通风方式。基于焊接烟羽热扩散机理,建立将超大焊接厂房分为上、中、下三层的模型框架,确定下层通风、中层通风、上层通风、下进上出通风四种通风方式。采用k-ε两方程湍流模型对四种通风方式下厂房焊接烟尘流动进行了三维模拟实验,得到了四种通风方式下焊接烟尘扩散随风量变化的空间分布规律。通过对比研究,得出下进上出通风方式能够在焊接烟尘最高允许浓度下获得最大纵向防尘深度,适合超大厂房焊接烟尘防治。

封闭式焊接车间通风方式的解决方案

通过分析焊接烟尘和焊接烟羽的特点,选取置换通风作为封闭式焊接车间的通风方式。利用CFD分别模拟了采用置换通风和混合通风的封闭式焊接车间,对比得到了置换通风的优越性。

Porosity sensitivity of A356 Al alloy during fiber laser welding

In order to decrease the metallurgical porosity and keyhole-induced porosity during deep penetration laser welding of Al and its alloys, and increase the mechanical properties of work-piece, the effects of welding parameters such as laser power, welding speed and defocusing value on both kinds of porosities were systemically analyzed respectively, and the shape and fluctuation of plume of the keyhole were observed to reflect the stability of the keyhole. The results show that increasing laser power or decreasing laser spot size can lead to the rising of both number and occupied area of pores in the weld; meanwhile, the plume fluctuates violently over the keyhole, which is always companied with the intense metallic vapor, liquid metal spatter and collapsing in the keyhole, thus more pores are generated in the weld. The porosity in the weld reaches the minimum at welding velocity of 2.0 m/min when laser power is 5 kW and defocusing value is 0.