In order to meet the current production needs of large-scale equipment parts in the manufacturing industry,and to improve the efficiency of grinding and polishing welding seam of large-scale engineering machinery cabs,a robot self-adaptive automatic grinding system was designed.In this system,a six degree-of-freedom robot with an adaptive force control system was used to achieve fit to complex curved surfaces and welds; an external axis was used to achieve full coverage of all welds of the workpiece,and the posture could be switched real-time to complete automatic polishing.Through the automatic replacement of grinding tools,the production efficiency of a single robot was maximized; the concept of module layering was used to enable different stations to meet the needs of different processes to highlight the good compatibility of the system; the adaptive power control device realized the digitization of industrial parameters,which were adjustable and controllable,so as to ensure the effect of grinding and polishing.The grinding and polishing test results of the welding seam of the excavator cab show that this system can be used to realize the fully automatic processing of the welding seam grinding and polishing of the large construction machinery cab,and the grinding effect is guaranteed.It can meet the production requirements.