Morishige KOICHI (森重 功一)

This paper describes a method for generating toolpaths based on machining strategies for five-axis controlled machining using special tools. Traditionally, most toolpath generation studies focused on ball-end mills, proposing strategic methods to achieve high-quality machining while avoiding tool interference. Recently, special finishing tools with large cutting edge radii have gained interest for achieving higher machining efficiency. These special tools can produce smooth finished surfaces even with large pick-feed widths, leading to higher productivity. However, unlike conventional machining with ball-end mills, five-axis controlled machining using special tools lacks standardized work design procedures. This study proposes a generic tool-geometry data format for defining special tool geometries and a method for generating toolpaths using this data format. This method strategically treats special tools as conventional ball-end mills. Consequently, five-axis controlled machining for new tool geometries can be achieved using existing operational procedures. To generate toolpaths, this study utilizes a two-dimensional configuration space (C-Space). For special tools with multiple cutting edge radii, the relationship between the tool posture and cutting edge contact point is clarified by mapping the cutting edge radius information onto the C-Space. By employing this mapped cutting edge information, we can determine the interference-free tool posture corresponding to the chosen cutting edge section based on the machining strategy. Finally, the paper presents machining simulations and experiments conducted to confirm the effectiveness of the proposed method.

Various operations in the production sites of manufacturing industries are being automated using industrial robots instead of operators. In recent years, an offline teaching method for robot motion has been implemented, where programs are generated in a work environment that is reproduced virtually inside a computer. However, the robot program developed using the offline teaching method can pass through singularities or suddenly change the robot’s posture, making the robot incapable of performing safe operations. To achieve optimal operation, the operator must determine the workpiece placement and create a robot program through trial and error. In this study, we proposed a method that uses manipulability to generate a program that commands the robot to move without passing singularities or changing the robot’s posture. Manipulability is quantitatively evaluated as an indicator of a robot’s ability to move its end effector in arbitrary directions. We proposed another method to determine the optimal workpiece placement for robot operations that can maximize the sum of manipulability during the operation. We implemented the aforementioned methods in an offline teaching system. We applied the developed system to a welding operation and verified its effectiveness by conducting motion simulations. The developed system was able to generate a practical robot program that maintained high manipulability and did not cause sudden changes in the posture or pass singularities. The developed system was able to simultaneously determine the optimal workpiece placement for the task, thereby confirming the usefulness of the proposed method.