Shim Selection for Tight-Tolerance Workpiece Fastening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in aircraft manufacturing is the efficient fastening of workpieces with tight tolerances, which can lead to internal stress and increased operation man-hours due to the need for individual shims to fill clearance gaps, especially in the aircraft industry where tolerance ratios are smaller than in other fields.
Innovation Solution
A manufacturing method and apparatus that derive a representative clearance value from statistical data to determine the appropriate shim or jig thickness for insertion, using tolerance, double-tolerance, difference, representative, and addition shims or jigs based on the clearance value relative to the tolerance, reducing the need for individual shim preparation and minimizing operation man-hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual shims are prepared for each clearance gap to ensure proper fastening, then fastening precision is improved, but operation man-hours and manufacturing complexity increase
Solution Approach 1:
The patent uses disposable test shims and jigs with specific thicknesses (tolerance shim, double-tolerance jig, difference shim, representative shim, addition jig) to determine clearance conditions. These test objects are discarded after use, replacing the need for complex individual shim preparation while maintaining fastening precision through systematic clearance classification.
Solution Approach 2:
The patent changes the parameter of shim thickness selection from individual customization to standardized categories. By deriving a representative clearance value from statistical data and comparing it against tolerance thresholds, the system determines which standardized shim or jig to use, transforming a complex individualized process into a parameter-based decision system.
2Manufacturing precision
If tight tolerances are applied to workpiece fastening, then fastening precision is improved, but internal stress and operation time increase
Solution Approach 1:
The patent performs preliminary action by deriving the representative clearance value from statistical data before the actual fastening operation. This pre-determination of clearance conditions allows operators to select the appropriate shim or jig in advance, eliminating time-consuming trial-and-error during assembly while maintaining tight tolerance requirements.
Solution Approach 2:
The patent segments the clearance gap into standardized categories (within tolerance, exceeding tolerance by specific amounts) and assigns specific test shims or jigs to each segment. This segmentation transforms a continuous clearance measurement into discrete, manageable categories, reducing operation time through systematic classification rather than individualized adjustment.
3Productivity
If representative clearance value is derived from statistical data, then shim fabrication rate is reduced, but measurement and data processing complexity increase
Solution Approach 1:
The patent creates a universal system where a single representative clearance value derived from statistical data serves multiple functions: it determines the clearance condition category, selects the appropriate test shim or jig thickness, and guides the fastening process. This multi-functionality reduces the need for multiple specialized measurement and selection procedures, improving productivity despite the initial data processing requirement.
Data Source
AI summary
A manufacturing method includes deriving, from statistic data, a representative value of a clearance provided between first and second workpieces, executing a first insertion process, and executing a second insertion process. The statistic data is obtained from measuring the clearance. The executing the first insertion process includes testing insertion of a tolerance shim into the clearance when the representative value is less than a tolerance of the clearance, and testing insertion of a double-tolerance jig into the clearance when the tolerance shim is insertable into the clearance. The executing the second insertion process includes testing insertion of a difference shim into the clearance when the representative value is greater than the tolerance, testing insertion of a representative shim into the clearance when the difference shim is insertable into the clearance, and testing insertion of an addition jig into the clearance when the representative shim is insertable into the clearance.