Design Of Welding Machine For A Cone Bottom

In modern national defense equipment manufacturing, welding is an essential procedure which can link material permanently. To achieve high quality welding joints, not only advanced welding technology is needed but also welding devices with higher degree of automation, higher precision and stability are required. This paper designed a special automatic welding machine for aluminum cone bottom work piece of a space instrument used in national defense based on the analyzing of work pieces’ material, structure, and welding requirements.Considering the welding quality, efficiency and cost, TIG (Tungsten Insert Gas arc Welding) was selected from a plurality of welding methods for aluminum. As is known about TIG, manual welding has many disadvantages such as low efficiency, demanding requirement of operators, low efficiency, and labor intensive so that it is not qualified to be used in high precision welding. Since manual TIG welding has no advantages in space instrument welding, automatic TIG with a welding robot was selected in this paper which overcome the defects above. To full use the robot and increase flexibility, as long as to keep welding seams horizontal, a welding positioner was used. By using a positioner, all seams are possible to get to a horizontal position and the welding robot is able to move faster. On the other hand, the dimension variation of work pieces, assemblage error or heat deformation during welding tasks will cause variation of seam locus which leads to weld defects. Since it is a significant cause of robot downtime and low productivity, the welding robot is required to be able to detect the seam deviation in real time and correct trajectory in time. A seam tracking mechanism was implemented on welding robot in our design.The machine is used to weld the transverse seams and the longitudinal seams of the work piece which consists of highly accurate positioner system, laser tracking system, and robotic welding devices. The hardware and software of the control system of special welding machine was designed based on Siemens S7-300PLC, Siemens S120servo drive, servo motor and ABB IRB-4600robot. A Siemens touchscreen was implemented for controlling and displaying the status, alarming information of high precision positioner.The interaction of welding robot with positioner and the real-time seam correcting can ensure high quality of welding.