Fastener Hole Preparation Using As-Built Thickness Mapping
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Solution Overview
Problem
Current methods for preparing fastener holes in parts during assembly, especially when dealing with composite materials and dissimilar materials, face challenges in accurately determining the thickness variations and selecting appropriate fastener lengths due to the limitations of traditional nondestructive inspection and drilling techniques.
Innovation Solution
A system and method that combines nondestructive inspection data with digital models to calculate as-built thickness values and deviations, allowing for the precise determination of fastener hole locations and lengths, and adjusts drilling parameters for numerically-controlled machines to ensure accurate hole preparation and fastener selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional nondestructive inspection methods are used to measure part thickness, then inspection can be performed, but measurement precision is insufficient especially in areas with abrupt thickness variations
Solution Approach 1:
The patent segments the thickness measurement process into multiple discrete measurement points across the part surface. By taking measurements at numerous locations and interpolating between them, the system achieves high precision thickness mapping even in complex geometries with abrupt thickness variations, resolving the contradiction between measurement precision and difficulty in such areas.
Solution Approach 2:
The patent transitions from point-based thickness measurements to a comprehensive surface-based thickness map by incorporating spatial coordinates and interpolating across the entire part surface. This dimensional expansion from discrete points to continuous surface data enables precise thickness determination in areas with abrupt variations that would be difficult to measure with traditional point-based methods.
2Measurement precision
If automated machines measure total thickness by calculating distance between holding tools, then measurement is obtained, but individual part thickness information is lost and accuracy is insufficient in abrupt thickness variation areas
Solution Approach 1:
The patent performs nondestructive inspection and creates a comprehensive thickness map of each part before assembly occurs. This preliminary measurement captures individual part thickness characteristics at multiple locations, preserving information that would otherwise be lost when parts are assembled and only total thickness can be measured. The pre-assembled thickness data enables precise determination of individual part dimensions.
Solution Approach 2:
The patent creates a digital copy or model of the actual part thickness distribution through nondestructive inspection. This digital thickness map serves as a virtual replica of the physical part's thickness characteristics, preserving individual part information without requiring physical disassembly. The digital model can be stored, analyzed, and used for manufacturing decisions while the physical part remains assembled.
3Manufacturing precision
If drilling parameters are set for expected thickness values, then drilling can proceed, but hole preparation accuracy deteriorates when actual thickness differs from expected
Solution Approach 1:
The patent implements a feedback loop where nondestructive inspection data revealing actual part thickness is fed back into the manufacturing process. The measured thickness values from the inspection system update the drilling parameters dynamically, allowing the drilling operation to compensate for thickness variations. This closed-loop approach ensures hole preparation accuracy matches actual part dimensions rather than relying on expected or nominal values.
Solution Approach 2:
The patent transitions from static, predetermined drilling parameters to dynamic parameters that adapt based on actual measured thickness. The system adjusts drilling depth, speed, and other parameters in real-time based on the nondestructive inspection data, enabling precise hole preparation that responds to actual part variations rather than following fixed pre-programmed values.
4Productivity
If manual methods are used for determining fastener lengths and preparing holes, then flexibility is maintained, but productivity is reduced and labor costs increase
Solution Approach 1:
The patent merges the nondestructive inspection system with the manufacturing and assembly system into an integrated workflow. The thickness measurement data from inspection is automatically fed into the drilling and fastener selection processes, eliminating manual measurement and calculation steps. This consolidation of inspection, manufacturing, and assembly functions into a unified system increases productivity while the integration manages complexity through automated data flow between stages.
Solution Approach 2:
The system performs self-service by automatically using its own inspection data to guide subsequent manufacturing operations without external intervention. The nondestructive inspection system provides thickness information that the manufacturing system uses autonomously to adjust drilling parameters and select fasteners, eliminating the need for separate manual measurement and decision-making processes. This self-utilization of data streamlines the workflow and boosts productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and efficiency of fastener hole preparation, reduces labor costs and cycle time, and improves assembly quality by automating the data collection and analysis process, enabling precise adjustments for thickness variations and material differences.
Implementation Method 1
nondestructive inspection, such as ultrasound inspection, will typically gather data about the part in the course of detecting and locating such characteristics
Data Source
AI summary
A method and system may be provided for determining a set of parameters for preparing a skin for assembly to a substructure. The skin may be nondestructively inspected to gather a data set relating to the skin thickness. Sets of as-built thickness values for the skin and of deviations from a nominal map of the skin thickness may be calculated. A mating area for the skin and substructure and a set of one or more locations for fastener holes in the mating area may be determined. A set of parameters for the one or more fastener holes and a set of one or more fastener lengths may be generated using the deviations. A tool may cut the one or more fastener holes using the set of parameters and the skin and substructure may be fastened using fasteners selected according to the generated set of one or more fastener lengths. The system may be used with a numerically-controlled machine, a nondestructive inspection system, and may include a computer coupled to the nondestructive inspection system for calculating the parameters for preparing the holes and the lengths of the one or more fasteners.