The instrument beam assembly is welded from 18 types of small stamping parts, and it is required to meet the production plan of 60,000 vehicles per year. The instrument beam has a large number of stamped parts, many types of sheet metal thicknesses, and the welding assembly has a certain level of difficulty. According to the process analysis, the suitable welding method is CO2 gas shielded welding, with a welding seam length of 1420mm and 45 weld segments. Since the weld positions are in a three-dimensional intersecting distribution and each bracket's position requires assembly precision, there are high automation requirements for this workstation. Manual welding significantly falls short in terms of welding quality, production rhythm, and product stability. Therefore, the final process plan determines that the entire assembly will be welded by utilizing CO2 gas shielded welding through a welding robot workstation for all welding spots.
Determining the height of the robot and the distances forwards, backwards, leftwards, and rightwards ensures that all welding points are covered within the workable range of the robot's welding gun. The most reliable method for optimization design is to simulate the actual welding work using robot simulation software. The method is to incorporate 3D models of the workstation fixtures, workpieces, and welding gun for assembly and debugging in a virtual environment to detect interferences, thus adjusting the relative sizes of each part for optimal results.
Each workstation can rotate reciprocally around the horizontal axis of the positioner. During welding, its posture can coordinate with the robot's movements to meet the welding process requirements. It mainly consists of 2 external axis servo motors (i.e., positioners) and their reducers, coordination software, converters, cables, 2 sets of fixture flipping mechanisms, a servo drive system, and so on. The 2 sets of flipping mechanisms are driven by positioners, and the system is realized by the robot control system.
The driven shaft is connected to the connecting plate and installed on the mounting base. The welding fixture flipping mechanism is connected to the connecting plate, and considering the processing errors and installation convenience of the welding fixture, the height of the positioner and driven shaft is adjustable. The driven shaft is a universal rotating bearing, thus avoiding mechanical processing errors, making installation and maintenance convenient.
Gun cleaning and silicone oil spraying device: a total of 1 set, consisting of a gun cleaning mechanism, clamping mechanism, and silicone oil spraying mechanism, etc. The actions are as follows: The robot moves the welding gun to the gun cleaning device—gun cleaning device clamps the welding gun—automatic gun cleaning—robot moves the welding gun to the silicone oil spraying area—silicone oil spraying—robot moves the welding gun back to its original position.
The welding fixture is a frame-type structure, facilitating the robot welding gun's approach to the workpiece. There are 25 movable positioning pins, 2 fixed positioning pin sleeves, and 3 fixed pins, facilitating the removal of workpieces from the fixture. The second workstation is identical to the first to increase capacity, to avoid waiting time for the robot, thus preventing the robot from stopping work during manual loading and unloading, improving work efficiency.
