搅拌头轴肩形状对6061铝合金FSW过程中轴向力的影响

Effect of shoulder shape on axial force of friction stir welding of 6061 aluminum alloy

为了机器人FSW工程化应用,研究搅拌头轴肩形状对轴向力的影响.采用平面与凹面两种轴肩形状的搅拌头,对6061-T6铝合金板材进行搅拌摩擦焊,测量、记录和分析焊接过程中的轴向力,建立轴肩受力模型,综合分析轴向力的分布及变化规律.结果表明,平面轴肩搅拌头焊接所得焊缝形貌优于凹面轴肩搅拌头;平稳焊接阶段轴向力分布曲线呈锯齿状波动,平面轴肩对应曲线的波动幅度较小;当搅拌头转速为1500 r/min、焊接速度为95 mm/min时测得轴向力最低,采用平面轴肩时所测轴向力为3828 N,而凹面轴肩则为4018.5 N.分析认为凹面轴肩产生的焊接热输入较小,材料上下方向塑性流动的阻力较大,相应的反作用力也较大.另外,根据受力分析,采用凹面轴肩焊接时,搅拌头前进方向的移动会叠加一定的轴向分力,导致凹面轴肩搅拌头焊接过程中所受的轴向力较大.

For the application of robotic FSW,the influence of shoulder shape on axial force during welding was researched.FSW of 6061-T6 aluminum alloy was successfully performed by tools with different shoulder shape of flat and concave.The axial force during welding was measured,recorded,and analyzed.The distribution and variation of axial force were analyzed comprehensively with the aid of an established stress model about the shoulder.The results were shown that weld morphology of the flat shoulder was better than that of the concave shoulder.The average axial force curve fluctuated zigzag in the stable welding stage,while the amplitude of zigzag with the flat shoulder was smaller than the concave shoulder.The lowest axial force was measured in rotating speed of 1500 r/min and the welding speed of 95 mm/min,when the flat shoulder was used,the lowest axial force was 3828 N,and the concave shoulder was 4018.5 N.It was attributed of the lower heat input produced welding with concave shoulder and greater resistance to plastic flow of material.In addition,according to the force analysis,when the concave shoulder was used for welding,a certain axial force was added by the movement in the forward direction,which resulted in a larger axial force.