Machining of holes in a large hybrid structure during its assembly using modular equipment

The study aimed to examine a technology for machining holes with an automatic drilling machine during the assembly of a large hybrid structure (polymer composite material + metal) with the use of modular equipment. In order to analyze the process of hole machining in large structures during their assembly, a wing box model measuring 17,765x3050x438 mm was assembled to simulate a civil aircraft wing box – a test wing box. The used modular equipment provides a geometric position accuracy of 0.5 mm in hole machining. In order to machine holes using an automatic drilling machine, a hole machining map was created. This map details key hole parameters such as hole diameter, hole accuracy, hole center coordinates, and hole axis direction, as well as material layers. To align the automatic drilling machine with a large structure, the map of holes to be machined should be divided into areas (in the case of long parts, into subareas). It was found that the technology for machining holes with numerically controlled automatic drilling machines using a combination tool allows holes to be machined in large hybrid structures to their final diameter in one or two passes, ensuring a geometric position accuracy of 0.5 mm. The study of hole machining in large structures revealed that in order to achieve a geometric position accuracy of 0.5 mm in automatic hole machining, long parts should be divided into subsections of no longer than 1 m. The overall length of the reference zone for the automatic drilling machine was determined. The obtained results can be used to optimize hole machining in large structures in aviation, shipbuilding, and other industries.