7005铝合金主桥节工作站MIG系统设计与焊接接头组织性能研究

Design of MIG system for 7005 aluminum alloy main bridge sectionworkstation and study on microstructure and properties of welded joints

应急桥梁作为灾害救援中能发挥出极大作用的救援装备,自身质量应尽量小,铝合金自身密度低、质量轻,可解决这个问题.但目前,应急桥梁的部件仍使用手工焊,这种方法不仅生产效率低,焊接的质量也不稳定.文中使用焊接工作站来焊接主桥节,分析了工件的尺寸、结构和焊缝位置,进行了总体方案的设计,选择了4台机器人搭配单台变位机的焊接方案,完成对工作站总体布局.并对主桥节材料7005铝合金进行了焊接接头组织和性能试验,选择使用单丝MIG焊完成对7005铝合金试样的焊接,并对试样进行力学性能测试.试验表明:焊缝的抗拉强度平均为290.74 MPa,断裂在热影响区;焊缝区的热影响区硬度最低,平均为75 HV,焊缝中心处区稍高,平均为115 HV,母材硬度最高,平均为165 HV.通过金相照片观察试样的接头组织,发现热影响区晶粒粗大,并分析了焊缝产生气孔以及焊缝热影响区软化的原因,并提出了解决措施,可以应用到实际生产中.

As the rescue equipment that can play a great role in disaster relief,the emergency bridge should be as small as possible.The aluminum alloy itself has low density and light weight,and can solve this problem.But at present,the emergency bridge parts are still using hand welding.This method is of low production efficiency,and welding quality is not stable.In this study,the welding workstation is used to weld the main bridge section,the size,structure and weld position of the workpiece are analyzed,and the overall scheme is designed.The welding scheme of four robots with a single positioner is selected to complete the overall layout of the workstation.The microstructure and properties of the welded joint of 7005 aluminum alloy,the main bridge material,were tested.The single wire MIG welding was used to complete the welding of 7005 aluminum alloy sample,and the mechanical properties of the sample were tested.The test shows that the average tensile strength of the weld is 290.74 MPa,and the fracture is in the heat-affected zone.The hardness of the weld zone is the lowest,with an average of 75HV;the weld center is slightly higher,with an average of 115HV;the base metal hardness is the highest,with an average of 165HV.By means of metallographic observation of the joint microstructure of the sample,it is found that the grain size of the heat affected zone is coarse,and the causes of porosity and softening of the weld heat affected zone are analyzed,and the solutions are put forward,which can be applied to the actual production.