| Industrial robots are widely used in handling, assembling, packaging, painting, product inspection and some other manufacturing processes. In recent years, robot milling processes which are becoming more and more popular are studied. On the occasions for some light materials and the accuracy request is not very high, industrial robots can replace the traditional CNC machine tools as they have the advantages of multi-degrees of freedom, moving agility, wide working range and low investment cost.The tool composed by spindle and milling cutter is installed at the end of the industrial robot so that it can have the milling capacity. The improved CC route method is used to generate the tool path. By adjusting the distance of constrain faces dynamically, the inhomogeneous problem of traditional CC method is avoided and the robot milling precision can be improved.It is necessary to make corresponding robot simulation before practical milling processing. In fact, robot milling has just begun to develop so the graphic simulation software does not have corresponding supplementary function for robot milling. In this paper, the supplementary software system is developed based on the open geometric modeling technology development platform Open Cascade(OCC) and object-oriented programming method. This system can recognize the CAD model of work-piece and obtain the geometric features of the model surfaces to be machined. Moreover, according to the robot model parameters, cutting parameters and the robot kinematics, it will automatically generate robot motion path.Simulation is carried out using the NC machining simulation software Vericut for finishing and rough milling processes. The simulation results show that the method of tool path generation have good feasibility and accuracy. Robot milling experiment is run by Staubli RX90. The repeatability of the robot is 0.02 mm and the material of the work-piece is polyethylene. In the experiment a ball-end cutter with 2.5mm-radius is used. The whole experiment process includes the calibration of tool coordinate system, the calibration of work-piece coordinate system, robot machining and experiment result analysis. A cylindrical surfaces work-piece and a part-spherical work-piece are milled. The profile error of cylindrical surface is within an acceptable range. According to experiment result, the reliability and feasibility of the software system is validated.It is proved that the improved CC route method can promote the development of robot milling technology. And the supplementary software system can provide effective supporting role for the robot milling process. In addition, it has significance for the development of robot milling technology and the application of robot technology. |
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