Research on the Robotic Free Abrasive Polishing System for the Rapid Spray Metal Tooling

Abstract

In the rapid spray metal tooling, metal film is spray-formed on the substrate and supported under the back, which will act as the working surface of the rapid metal tool finally. So the finishing process for the sprayed metal film is important to the quality and the lifecycle of the rapid metal tool. The finishing of the metal mould is frequently carried out manually, these kinds of operations are iterative, time consuming and require experience. Automation can introduce cost reduction minimizing production times on such manual finishing operations. This paper presents a robotic polishing system with free abrasive for the finishing of the rapid spray metal tool, which is consisted of a six-degree-of-freedom industrial robot manipulator, a high speed electrical polishing spindle and a numerical swivel table. Soft polishing pad and free abrasive are also selected for the robotic polishing system. The path planning is so important to the robotic polishing system that a partition & flexible path mapping method basing on UG CAM is developed to generate the uniform robotic polishing path on the complex mould surface. UG/Open GRIP programming module is used to generate the driving paths with different path intervals on the predesigned plane for each partitioned part. When the driving paths are projected to the mould curved surface, the uniform polishing paths with NC code can be generated by the multi-axis CAM module of the UG. And the path with NC code can then be transformed to the robotic polishing path. According to the elastic deformation and the abrasion of the soft polishing tool, the robotic polishing path should be adjusted to keep the smooth polishing process by offsetting the pre-compressed value and the abrasive compensation value along the polishing axis direction. Technical parameters of the robotic polishing process are also optimized through the experiments. Finally, the rapid metal punch mould is finished to test the robotic polishing system.