Structural Joint Hole Alignment Using CMM-Guided CNC Drilling
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Solution Overview
Problem
The existing methods for joining structural components, such as aircraft structures, face challenges including unstable drilling platforms, high rates of oversize holes, ergonomic access issues, and time-consuming processes, especially when dealing with titanium components and large-scale integration areas, which result in significant foreign object debris and manual cleaning requirements.
Innovation Solution
A method and system utilizing a coordinate measurement machine with an articulated measurement arm to measure and align pre-drilled holes in structural components, generating a CNC program for precise hole drilling in a stable fixture, and inserting fasteners through aligned holes to secure structures, eliminating the need for manual drilling and reducing oversize holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drill jigs are used to drill primary structure joints, then hole location accuracy is improved, but drilling platform stability deteriorates resulting in large percentage of oversize holes
Solution Approach 1:
The process is divided into two separate operations: first measuring existing holes with a CMM to capture their actual locations and orientations, then using this data to program a CNC drilling operation. This segmentation allows the measurement function to be performed on the actual workpiece geometry while the drilling is performed on a stable platform, resolving the contradiction between measuring accuracy and platform stability.
Solution Approach 2:
A coordinate measurement machine (CMM) acts as an intermediary to capture the actual hole locations and orientations on the workpiece. This measurement data serves as a mediator between the irregular workpiece geometry and the stable CNC drilling platform, allowing accurate hole location to be achieved without requiring the drilling platform to conform to the workpiece's irregularities.
2Ease of operation
If manual drilling is performed in large scale integration areas, then access to joint areas is improved, but ergonomic risks increase and drilling becomes time consuming
Solution Approach 1:
Manual drilling operations are replaced with automated CNC drilling. The CNC machine, programmed with hole locations and orientations measured by the CMM, automatically performs the drilling operation. This substitution eliminates the time-consuming nature of manual drilling while maintaining access to joint areas through the use of appropriate fixtures and positioning systems.
3Power
If large manual tools are used for drilling holes in confined areas, then drilling capability is improved, but drilling access issues arise in confined areas
Solution Approach 1:
The hole locations and orientations are measured and programmed in advance using the CMM before the actual drilling operation. This preliminary measurement and programming allows the drilling process to be optimized for the specific geometry and access constraints of each joint area, enabling the use of appropriately sized tools that can access confined areas while maintaining drilling capability.
4Ease of manufacture
If drilling is performed on aircraft structures, then structural assembly is achieved, but significant amount of foreign object debris is created requiring manual cleaning
Solution Approach 1:
Manual drilling operations are replaced with CNC drilling, which provides more controlled and consistent drilling performance. This substitution reduces the generation of foreign object debris through better chip evacuation and more precise hole formation. Additionally, the CNC process can be programmed to minimize debris generation and facilitate easier cleanup compared to manual operations.
Data Source
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AI summary
A method includes making a first structure (26) with a first plurality of pre-drilled holes (52) at pre-defined locations, making a second structure (28) with a second plurality of pre-drilled holes (50) at pre-defined locations, making a third structure (30) without pre-drilled full-size holes, measuring the location and orientation of the first and second plurality of pre-drilled holes in the first and second structures, determining the location of a third plurality of holes (64T, 64S) to be drilled in the third structure that correspond to first and second plurality of pre-drilled holes measured in the first and second structures, creating a program (89) to drill the third plurality of holes in the third structure that align with the measured location and orientation of the first and second plurality of pre-drilled holes in the first and second structures based on the measure location and orientation of the first and second plurality of pre-drilled holes in the first and second structure, drilling the third plurality of holes (64T, 64S) in the third structure (30) based on the program, positioning the third structure on the first and second structures such that the third plurality of holes in the third structure are aligned with the first and second plurality of pre-drilled holes in the first and second structures, and inserting fasteners (68) through the third plurality of holes and the first and second plurality of predrilled holes that are aligned with the third plurality of holes to secure the second structure to the first structure using the third structure.