Sheet Metal Joint With Bolt-and-Slot Locking for Blind Assembly

Solution Overview

Problem

Existing methods for joining sheet metal parts require access to the side facing away from the other, which is not always feasible, especially in constructions like drywall or lightweight steel, leading to incomplete cladding and increased labor for precise alignment.

Innovation Solution

A sheet metal joint with a receiving opening in one part and a connecting bolt that projects orthogonally from the other part, featuring a constriction and shoulder section for a positive-locking connection, allowing alignment and secure attachment without requiring access to the inner side.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screw or rivet connections are used to join sheet metal parts, then the parts can be securely connected, but access to the inner side of the sheet metal parts is required which is not always feasible

Engineering Contradiction:

Improveconnection reliabilityVSAvoidaccessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent inverts the traditional connection approach by having the connecting element (connecting piece) attached to one sheet metal part and extending through a receiving opening in the other part, rather than requiring access to both sides for traditional fastening. The connecting piece has a fastening section that attaches to the first sheet metal part and a connecting section that protrudes through the receiving opening to engage with the second sheet metal part, enabling connection without accessing the inner sides of both parts.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The connecting piece is inserted through the receiving opening and nested within the structure formed by the two sheet metal parts. The connecting section of the connecting piece fits into the receiving opening, creating a nested arrangement that secures the connection while maintaining accessibility from only one side.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If traditional connections are used, then sheet metal parts can be joined, but precise alignment and correct positioning must be ensured manually which increases labor

Engineering Contradiction:

Improveconnection strengthVSAvoidassembly efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The receiving opening is pre-formed in the first sheet metal part with specific geometric features (narrower section and wider section) that guide the connecting piece into correct alignment during insertion. The connecting piece is designed with corresponding geometric features that interact with the receiving opening to automatically establish proper positioning and orientation, eliminating the need for manual alignment adjustments during assembly.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If sheet metal parts are joined with access to both sides, then precise alignment can be achieved, but in clad constructions the inner surfaces are inaccessible

Engineering Contradiction:

Improvealignment precisionVSAvoidaccessibility

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent inverts the traditional connection approach by having the connecting element (connecting piece) attached to one sheet metal part and extending through a receiving opening in the other part, rather than requiring access to both sides for traditional fastening. The connecting piece has a fastening section that attaches to the first sheet metal part and a connecting section that protrudes through the receiving opening to engage with the second sheet metal part, enabling connection without accessing the inner sides of both parts.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The connecting piece serves as an intermediary element that bridges the two sheet metal parts. It is attached to the first sheet metal part and extends through the receiving opening to connect with the second sheet metal part, mediating the connection between the two parts without requiring direct access to their inner surfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP4386216B1Sheet metal connection

Publication Date: 2026.03.18 PROTEKTORWERK FLORENZ MAISCH GMBH & CO KG

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AI summary

A sheet metal joint comprises a receiving opening formed in a flat contact surface of a first sheet metal part and a connecting bolt extending along a bolt axis and configured to be attached to a flat contact surface of a second sheet metal part with a fastening section such that the connecting bolt projects orthogonally from the contact surface of the second sheet metal part. The connecting section comprises a constriction section and a shoulder section, which adjoins the constriction section along the bolt axis in a direction away from the fastening section and has a larger diameter than the constriction section.The receiving opening extends along a longitudinal direction parallel to the contact surface of the first sheet metal part from an insertion section to a locking section, wherein the insertion section has a width transverse to the longitudinal direction that is greater than the diameter of the shoulder section mentioned, and the locking section has a width transverse to the longitudinal direction that is smaller than the diameter of the shoulder section mentioned and preferably corresponds at least substantially to the diameter of the constriction section mentioned.