Multi-Leaf Fire Door with Interlocking Metal Steps
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Solution Overview
Problem
Conventional multi-leaf fire protection doors face challenges in withstanding high bending forces during fires, leading to potential gaps that allow hot gases to escape, especially when not locked, due to the 'bi-metal effect' causing differential thermal expansion between sheet metal jacket panels.
Innovation Solution
The design features sheet metal door leaves with complementary metal steps and projections that engage behind each other when closed, forming a continuous rear grip on one side, which provides additional support points and seals the door effectively, allowing for the use of a standard lock instead of complex locking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sheet metal door leaves are used without additional engagement structures, then manufacturing is simpler and material usage is reduced, but the door cannot withstand high bending forces during fires and may create gaps allowing hot gases to escape
Solution Approach 1:
The door leaf is divided into multiple functional segments: the sheet metal jacket provides structural enclosure, the infill material provides thermal insulation and fire resistance, and the complementary metal steps provide mechanical engagement. This segmentation allows each component to optimize its specific function while working together to withstand fire conditions.
Solution Approach 2:
The complementary metal steps are integrated within the thickness of the sheet metal jacket, with one step nested within the profile of another. This nested arrangement creates the engagement mechanism without adding external complexity, maintaining a compact door leaf structure while providing the necessary fire resistance.
2Reliability
If complex locking systems with multiple catches are used to secure door leaves during fires, then the door can withstand bending forces better, but the device complexity increases and standard locks cannot be used
Solution Approach 1:
The complementary metal steps automatically engage with each other when the door leaves are closed, providing self-locking functionality without requiring additional catches or complex locking mechanisms. The structure itself serves the locking function, allowing standard locks to be used while maintaining security during fire conditions.
Solution Approach 2:
The locking function is merged with the structural engagement of the door leaves. The complementary metal steps that provide fire resistance also serve as the locking mechanism, combining two functions into a single integrated structure and eliminating the need for separate complex locking systems.
3Strength
If multiple support points and catches are added to hold door leaves during fires, then bending forces are better distributed, but manufacturing complexity and material usage increase
Solution Approach 1:
The geometry of the metal steps is optimized with specific dimensional parameters that enable effective engagement. By carefully selecting the depth, width, and positioning of the steps, the design achieves sufficient strength to withstand fire conditions while maintaining manufacturability and avoiding excessive material usage.
Solution Approach 2:
The engagement mechanism utilizes the thickness dimension of the sheet metal jacket by forming complementary steps within the profile. This three-dimensional engagement provides multiple support points for distributing bending forces while being integrated into a single door leaf component, simplifying manufacture compared to multiple separate support structures.
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
This configuration enhances the fire door's ability to absorb bending forces and prevent gas escape, even when not locked, by distributing forces evenly and maintaining a secure seal, thus simplifying production and reducing material usage.
Implementation Method 1
a seal made of material that foams up in the event of a fire and serves to fill the door gap between the two fire-rated door leaves with foam in the event of a fire
Implementation Method 2
The shell sheet facing the fire expands more than the sheet facing away from the fire due to the greater heat. Due to the different thermal expansion, the entire door panel of the door leaf comes under considerable tension and bends accordingly
Data Source
AI summary
The multi-wing fire protection door (10) has fire protection door wings (14,18) swiveling to vertical axes so that the fire protection wings detect each other in the closed state of the fire protection door. The fire protection door wings are constructed by jacket sheets (26,30) with a filling (34). The jacket sheets are formed such that the sheets get caught each other or behind-seized in the closed state.