Hook-In Connector Structure for High-Load Timber Joints

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Solution Overview

Problem

Existing connectors for heavy-duty applications in timber engineering face issues with load-bearing capacity, durability, and size, as dovetail connections can deform or fail under high loads, leading to loosening and potential failure.

Innovation Solution

The connector design distributes main loads evenly across its width through webs and lips interacting with undercuts, enhancing torsional rigidity and allowing higher force absorption with the same size or smaller dimensions, while also providing secure anchoring and easier handling through reduced overlap and optional play adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If narrow dovetail connections are used, then the connector size is reduced, but the load-bearing capacity decreases and the dovetail grooves can deform or tear out under high loads

Engineering Contradiction:
Improveload-bearing capacityVSAvoidconnector size
Core Design Contradiction:
StrengthVSVolume of stationary object

Solution Approach 1:

The invention transitions from narrow dovetail connections to wide transverse lips and webs that distribute loads across the entire width of the connector. This dimensional expansion from narrow to wide contact surfaces allows the connector to accommodate high loads without increasing overall size, as the load distribution occurs transversely rather than through deep dovetail engagement.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The connector employs different structural elements for different functions: lips and webs provide broad load distribution across the width, while undercuts provide localized mechanical interlocking. This differentiation allows optimal performance in both load-bearing capacity and resistance to deformation without requiring uniform structural reinforcement throughout.

Inventive Principle:
Principle #3Local quality

2Strength

If deep overlap between lips and undercuts is used, then the connection strength is increased, but the hanging distance increases and handling becomes more difficult

Engineering Contradiction:
Improveconnection strengthVSAvoidhanging distance
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The invention shifts the load-bearing mechanism from deep longitudinal overlap to broad transverse contact surfaces. The lips and webs extend across the entire width of the connector, creating large contact areas that provide strong mechanical interlocking with undercuts while requiring minimal overlap distance in the hanging direction.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The broad transverse contact surfaces of the lips and webs provide sufficient mechanical engagement area to achieve strong connections with reduced overlap requirements. The excessive width of the contact surfaces compensates for the reduced longitudinal overlap, maintaining connection strength while shortening the hanging distance.

Inventive Principle:
Principle #16Partial or excessive action

3Manufacturing precision

If the thickness of the lip is increased to achieve play-free connection, then the alignment precision is improved, but the device complexity increases

Engineering Contradiction:
Improvealignment precisionVSAvoidconnector complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention adjusts the thickness parameter of the lip to optimize the balance between play-free connection and manufacturing simplicity. By carefully selecting the lip thickness to match the undercut dimensions, the design achieves precise alignment and play-free connection through the natural geometry of the components without requiring additional alignment features or complex adjustment mechanisms.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3985189B1Connector for two workpieces
Publication Date: 2023.12.06 KNAPP GMBH
  • EP3985189B1 patent drawingFigure 1~2
  • EP3985189B1 patent drawingFigure 3~4
  • EP3985189B1 patent drawingFigure 5~6

AI summary

The invention relates to a connector (1) for two workpieces (2, 3), comprising two fittings (4, 5), each having a mounting side (6) for a workpiece (2, 3) and an opposite connecting side (7) on which they can be hooked into one another in a hooking direction (R) parallel to the connecting side (7), wherein each fitting (4, 5) has on its connecting side (7) a shoulder (11) extending transversely to the hooking direction (R) over its entire width (B) with an undercut (14) which leaves a web (16) on the shoulder (11), and its end face (13) furthest from the shoulder (11) and adjacent to the connecting side (7) has a lip (17) extending transversely to the hooking direction (R) over its entire width (B) and adjacent to the connecting side (7), and wherein in a first hooked position of the fittings (4, 5) the lip (17) of each The fitting (4, 5) engages in the undercut (14) of the other fitting (5, 4).