Foam-Filled Door Leaf Structure for Flat Insulated Front Doors

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Solution Overview

Problem

Existing methods for manufacturing building doors, particularly front doors, result in bulky and expensive products with uneven surfaces due to the foaming process, which complicates production and affects visual appeal.

Innovation Solution

A method involving forming a door leaf cavity with inward projections that taper towards the edges, allowing for the use of insulating foam without excessive pressure, and utilizing fiber-reinforced plastic frame profiles and polyurethane wedge profiles to control shrinkage and ensure a flat, even surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the door leaf cavity is filled with insulating foam to provide thermal insulation, then thermal insulation performance is improved, but the foam pressure creates unsightly dents and bulges on the door leaf surface

Engineering Contradiction:

Improvethermal insulation performanceVSAvoidsurface flatness

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The projection is strategically positioned at specific locations within the door leaf cavity, creating localized regions of reduced foam volume. This allows the foam to be contained in controlled areas, preventing uncontrolled expansion and surface deformation while maintaining overall thermal insulation performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The projection is pre-formed as part of the door leaf structure before the foam filling process. This preliminary structural feature dictates how the foam will expand and distributes the foam pressure in advance, preventing surface defects before they occur.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the door leaf cavity is filled with insulating foam to reduce weight and improve insulation, then manufacturing cost and complexity are reduced, but the foam shrinkage during curing creates gaps and surface unevenness

Engineering Contradiction:

Improvemanufacturing cost and complexityVSAvoidsurface evenness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The projection creates localized foam containment zones that control the shrinkage behavior during curing. By restricting foam movement to specific regions, the projection ensures uniform shrinkage distribution and prevents gap formation at the perimeter.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The projection acts as a cushioning element that absorbs and distributes the shrinkage stresses during foam curing. This preliminary structural feature compensates for the expected shrinkage, maintaining surface evenness throughout the door leaf.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If a frame with thermal break elements is used to provide thermal insulation, then thermal insulation performance is improved, but the door leaf becomes thick and bulky

Engineering Contradiction:

Improvethermal insulation performanceVSAvoiddoor leaf thickness

Core Design Contradiction:

TemperatureVSVolume of moving object

Solution Approach 1:

The patent uses foam material as an insulating filler within the door leaf cavity. Foam is a porous material that provides effective thermal insulation through its cellular structure, achieving the required insulation performance without adding significant thickness to the door leaf.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

Instead of providing thermal insulation through the frame structure (one-dimensional approach), the patent fills the internal cavity of the door leaf with insulating foam (three-dimensional approach). This volumetric insulation method achieves superior thermal performance while maintaining a compact door leaf profile.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 method reduces production costs and complexity, achieves a visually superior door leaf with improved thermal insulation and minimal surface imperfections, enhancing customer satisfaction.

Implementation Method 1

filling the door leaf cavity with insulating foam

Methodology Applied

Scientific EffectFoaming process: Foam

Implementation Method 2

providing good thermal insulation

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

During the curing process, the insulating material also shrinks, creating a gap around the perimeter

Methodology Applied

Scientific EffectShrinkage: Thermal Contraction

Data Source

PatentEP2581543B1Methof for manufacturing a buidling door leaf, and a buidling door leaf

Publication Date: 2025.12.17 HORMANN KG ECKELHAUSEN

Figure 1

AI summary

The invention relates to a method for manufacturing a building door leaf (12), in particular a front door leaf, wherein a door leaf cavity (50) is formed which is bounded by side edges (44) forming narrow end faces (35) and panel elements (42) forming wide sides (34, 40) of the door leaf, wherein at least one projection (58) extending along the side edges (44) and projecting into the door leaf cavity (50) is arranged in the door leaf cavity (50) on at least one of the side edges (44), which has side surfaces (59) facing the panel elements (42), at least one of which extends obliquely towards the associated panel element (42) such that the door leaf cavity (50) tapers from the inside out towards the side edge (44) and wherein the door leaf cavity (50) is filled with foam.The invention further relates to a door leaf frame profile (48) for use in the method and to a door leaf (12) that is obtainable by such a method.