Dimpled Sheet Assembly with Variable Tenon Lengths

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Solution Overview

Problem

The assembly of sheet metal structures for armored vehicles is challenging due to the need for precise alignment of tenons and mortises, which often results in jamming and requires flexible materials, making it difficult to achieve robust and precise connections, especially with heavy and bulky armor plates.

Innovation Solution

The solution involves creating a structure where each tenon has a unique length, allowing for independent docking with its corresponding mortise, and assembling them in order from longest to shortest, facilitating precise alignment and simplifying the assembly process by focusing on one tenon/mortise pair at a time, followed by welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If all tenons have the same length and are assembled simultaneously, then the assembly operation is simplified, but jamming occurs due to multiple alignments required between tenon/mortise pairs

Engineering Contradiction:
Improveassembly operationVSAvoidjamming
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The assembly process is segmented into sequential operations, with each tenon/mortise pair assembled independently in order from longest to shortest tenon. This segmentation eliminates the simultaneous alignment requirement that causes jamming, allowing each connection to be made separately without interference from other tenons.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If tolerances are adjusted or sheet bending is used to simplify assembly, then the assembly operation becomes easier, but precision and robustness of armor plates are compromised

Engineering Contradiction:
Improveassembly operationVSAvoidprecision between tenons and mortises
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The tenons are pre-sorted by length before the assembly process begins. This preliminary action establishes a clear assembly sequence (longest to shortest) that guides the operator through precise, sequential connections without requiring tolerance adjustments or sheet bending, thereby maintaining both ease of operation and manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If sequential assembly of each tenon/mortise couple is performed, then precision and robustness are improved, but the assembly process becomes more complex

Engineering Contradiction:
Improveprecision between tenons and mortisesVSAvoidassembly process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Each tenon is given a specific local quality (unique length) that determines its position in the assembly sequence. This local differentiation simplifies the overall process by creating a natural assembly order, where the longest tenon is assembled first, followed by progressively shorter ones, reducing the cognitive complexity despite the sequential nature of the operation.

Inventive Principle:
Principle #3Local quality

4Manufacturing precision

If non-identical tenon lengths are used for independent docking, then assembly precision is improved, but the device complexity increases

Engineering Contradiction:
Improvealignment precisionVSAvoidtenon length variation
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tenons are designed with asymmetric lengths rather than uniform dimensions. This asymmetry is functional, creating a tapered sequence from longest to shortest that enables precise sequential assembly. The asymmetric design simplifies alignment by ensuring each tenon engages its mortise at a distinct stage, reducing the complexity of achieving precise alignment compared to uniform tenons requiring simultaneous alignment.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP2500117B1Structure of sheets assembled by dimpling and method for assembling such a structure
Publication Date: 2013.10.02 NEXTER SYST SA
  • EP2500117B1 patent drawingFigure 1
  • EP2500117B1 patent drawingFigure 2
  • EP2500117B1 patent drawingFigure 3

AI summary

The structure has a first sheet (1) including an edge (2) provided with a series of tenons (4a-4e) corresponding to housing recesses of a second sheet (5), where welding is performed at an upper surface of the second sheet. Each tenon has length different from length of the other tenons, where difference in height between the tenons is greater than thickness of the second sheet. The first sheet is plain or non-plain. The tenons are leveled to not exceed a lower surface (6) of the second sheet after welding of the first sheet on the second sheet. An independent claim is also included for a method for assembling a sheet structure.