Aircraft Structure Connection for Three-Directional Tolerance Compensation
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Solution Overview
Problem
Current methods for assembling aircraft primary structures face challenges with managing manufacturing tolerances, leading to difficult and time-consuming interface management, potential build-in stresses, and the need for additional parts like shims.
Innovation Solution
A connection system with three-directional tolerance compensation means, including first, second, and third tolerance compensation means, and joining means, allows for quick assembly by adjusting in longitudinal, horizontal, and vertical directions, using elements like threaded rings and eccentric bushes to compensate for tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional riveting methods are used to join cross beams to frames at multiple interfaces simultaneously, then the structural connection is achieved, but manufacturing tolerances accumulate leading to build-in stresses and requiring additional parts like shims
Solution Approach 1:
The tolerance compensation mechanism is divided into multiple independent adjustment elements: first tolerance compensation means for longitudinal direction, second for horizontal direction, and third for vertical direction. Each direction has its own adjustment mechanism that can be independently controlled, allowing precise compensation without complex interdependent adjustments.
Solution Approach 2:
The floor grid is pre-assembled outside the fuselage shell where tolerance accumulation is avoided. The tolerance compensation mechanisms are pre-installed on the frames before the floor grid is installed. This preliminary preparation allows the entire floor grid to be installed as a complete unit without managing multiple interfaces simultaneously during final assembly.
2Productivity
If multiple interfaces are assembled simultaneously to manage all connections, then complete structure assembly is achieved, but time consumption increases and tolerance management becomes difficult
Solution Approach 1:
The floor grid is pre-assembled outside the fuselage shell where tolerance accumulation is avoided. The tolerance compensation mechanisms are pre-installed on the frames before the floor grid is installed. This preliminary preparation allows the entire floor grid to be installed as a complete unit without managing multiple interfaces simultaneously during final assembly.
Solution Approach 2:
The tolerance compensation mechanisms act as intermediaries between the frames and the floor grid. These mechanisms absorb and compensate for tolerance deviations, allowing the floor grid to be installed without precise manual adjustment at each interface. The intermediaries enable quick installation while maintaining alignment precision.
3Manufacturing precision
If contact surfaces are positioned exactly to each other during riveting, then precise alignment is achieved, but additional parts such as shims are required and assembly becomes more complex
Solution Approach 1:
The tolerance compensation function is extracted from the traditional rigid riveting connection and implemented through dedicated adjustment mechanisms. These mechanisms take out the need for shims and other additional parts by providing built-in adjustment capability that absorbs tolerance deviations directly in the connection system.
Solution Approach 2:
The connection system allows parameter changes in position and orientation through the tolerance compensation mechanisms. The first, second, and third tolerance compensation means enable adjustment of the connection parameters in longitudinal, horizontal, and vertical directions respectively, allowing precise alignment without requiring additional parts like shims to make up tolerance gaps.
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
Enables quick, stress-relieved assembly of aircraft primary structures by pre-assembling the floor grid outside the fuselage, eliminating tolerances in all directions, and ensuring precise alignment without additional parts.
Implementation Method 1
a first element with a through hole provided with an internal thread adapted to be fixed to the first part, for instance a frame, and a threaded ring adapted to be in engagement with the internal thread of the first element. Th first tolerance compensation means enables a tolerance combination in longitudinal direction. Due to the thread engagement a sensitive adjustment in axial direction is possible.
Implementation Method 2
The second tolerance compensation means can comprise an eccentric bush, which is adapted to be placed in a through hole of the second part, for instance a cross beam. By means of the eccentric bush, a tolerance compensation perpendicular to the longitudinal direction can be achieved just by rotating the bush inside the through hole of the second part.
Implementation Method 3
The joining means can comprise a screw and a nut. The screw can have a head, a shaft and a threaded portion. The shaft is adapted to be put through the eccentric bushes and the threaded portion is adapted to receive the nut such that a clamping force in the first direction is created forcing the head in direct or indirect contact against the threaded ring and the nut in direct or indirect contact against the second part.
Data Source
Figure 1
Figure 2~4
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AI summary
Disclosed is a connection system (1) for joining at least two parts (2,4), for instance for joining a primary structure of an aircraft, comprising first tolerance compensation means (6) in a first direction, second tolerance compensation means (8) in a second direction, third tolerance compensation means (10) in a third direction and joining means (13) in the first direction, a joining method and a primary structure.