Holt, S. and Clauss, R., "Robotic Drilling and Countersinking on Highly Curved Surfaces," SAE Technical Paper 2015-01-2517, 2015, doi:10.4271/2015-01-2517.
Electroimpact has developed a novel method for accurately drilling and countersinking holes on highly convex parts using an articulated arm robotic drilling system. Highly curved parts, such as the leading edge of an aircraft wing, present numerous challenges when attempting to drill normal to the part surface and produce tight tolerance countersinks. Electroipmact's Accurate Robot technology allows extremely accurate positioning of the tool point and the spindle vector orientation. However, due to the high local curvature of the part, even a small positional deviation of the tool point can result in a significantly different normal vector than expected from an NC program. An off-normal hole will result in an out of tolerance countersink and a non-flush fastener. A compliant contact pad with normality feedback is commonly used to locally normalize to a work part but in the case of highly curved parts, a flat contact pad has too small of a contact area with the panel to allow accurate local normalization. Electroimpact has developed a pneumatically actuated four-point lander on a compliant contact pad with normality feedback. This development, along with Electroimpact's Accurate Robot technology allows for automated drilling and countersinking on parts that have previously been unachievable with robotic drilling systems.