“Process-To-Part” Robotic Machining and Metrology for Large Nuclear Power Plant Component Manufacturing - Capability of a Photogrammetry-Based Solution

In the nuclear industry, setting up manufacturing facilities capable of machining and inspecting large power plant components such as reactor pressure vessels, steam generators and pressurisers is highly capital intensive and demands high operating costs. Also, remounting work pieces onto machine tools for correction of defects exposed during inspection potentially creates even more due to realignment difficulties. This all motivates the consideration of using robotics to facilitate “process-to-part” machining and inspection. However, the inherent downfalls of robotics mean improvements to machining accuracy are required before they can be adopted. A proposed solution to this involves utilising the desired inspection capability to feedback measurement data to automate the correction of machining programs to offset inherent inaccuracies. This paper presents early stage experimental research assessing the capability of a photogrammetric inspection system mounted onto a Fanuc F200iB hexapod, which involved repeatedly measuring reference artifacts with known dimensions to acquire data for accuracy and repeatability computations. The main conclusion that can be drawn from this work is that the low cost photogrammetry system tested is capable of inspecting lower tolerance features of large nuclear power plant components but that a range of improvements can be made to gain a level of capability suitable for inspecting higher tolerance features. These have been summarised and details of further work has been given to develop this concept further for use in this application. This contribution therefore advances the understanding of “process-to-part” machining and inspection in the nuclear industry and provides a key step towards realising its benefits.