Foam-Core Architectural Interior Door With Reinforced Hardware Mounts

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Solution Overview

Problem

Wood-based interior doors face issues such as warping, rotting, mold, pest attacks, combustibility, and inconsistency, while alternative materials like rigid polyisocyanurate/polyurethane foam lack sufficient structural integrity for securing hardware.

Innovation Solution

Incorporating strategically placed structural inserts made of rigid or semi-rigid materials, such as plastic, metal, or wood, into the mold before pouring polyisocyanurate/polyurethane foam to provide structural support for hinges, handles, and locks, and optionally using a durable coating for protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If wood-based materials are used for interior doors, then aesthetic appeal and traditional appearance are improved, but the door becomes susceptible to warping, rotting, mold, pest attacks, and combustibility

Engineering Contradiction:
Improveaesthetic appealVSAvoidresistance to warping, rotting, mold, pests
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies composite materials by combining rigid polyisocyanurate/polyurethane foam core with wood veneers and metal reinforcement strips. The foam core provides resistance to warping, rotting, mold, and pests, while wood veneers applied to the stiles and rails provide aesthetic appeal. This composite structure resolves the contradiction by integrating materials with complementary properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by using different materials in different locations of the door. Wood veneers are applied only to the stiles and rails where aesthetic appeal is needed, while the foam core is used in the panel areas where resistance to environmental degradation is most critical. Metal reinforcement strips are strategically placed to provide localized structural support.

Inventive Principle:
Principle #3Local quality

2Strength

If solid wood is used for door construction, then structural strength and durability are improved, but the cost increases and wood availability decreases

Engineering Contradiction:
Improvestructural strengthVSAvoidwood consumption
Core Design Contradiction:
StrengthVSQuantity of substance

Solution Approach 1:

The patent uses composite materials where rigid polyisocyanurate/polyurethane foam serves as the core material, providing structural strength and durability without requiring large quantities of wood. Wood veneers are applied only to the stiles and rails to provide the necessary structural framework and aesthetic appearance, significantly reducing overall wood consumption compared to solid wood construction.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by substituting solid wood with a foam core that has comparable or superior structural properties. The foam core provides adequate strength for interior door applications while dramatically reducing material consumption and cost.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If alternative materials like rigid foam are used for door construction, then resistance to warping, rotting, and pests is improved, but structural integrity for securing hardware deteriorates

Engineering Contradiction:
Improveresistance to warping, rotting, pestsVSAvoidstructural integrity for hardware
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses composite materials where rigid polyisocyanurate/polyurethane foam provides resistance to warping, rotting, and pests, while metal reinforcement strips embedded in the foam core provide the necessary structural integrity for securing hinges, handles, and locks. This combination resolves the contradiction by integrating materials with complementary strengths.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by strategically placing metal reinforcement strips at specific locations where hardware needs to be secured. The foam core maintains its superior resistance to environmental degradation in the panel areas, while metal provides localized structural support at the stiles and rails where hardware attachment is required.

Inventive Principle:
Principle #3Local quality

4Ease of manufacture

If wood veneers are applied to foam core, then aesthetic appeal is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveaesthetic appealVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-attaching wood veneers to the stiles and rails before assembling the door. The foam core is also pre-cut and prepared with channels for metal reinforcement strips before final assembly. This preliminary preparation simplifies the overall manufacturing process by organizing complex tasks into manageable pre-assemblies.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies segmentation by dividing the door into separate components: foam core, wood veneer-covered stiles and rails, and metal reinforcement strips. Each component is manufactured and prepared separately, then assembled into the final door product. This segmentation reduces manufacturing complexity by allowing specialized production of each component.

Inventive Principle:
Principle #1Segmentation

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

The solution provides a structurally sound, lightweight, and aesthetically appealing door with improved thermal and acoustic insulation, fire retardancy, and resistance to pests and moisture, while maintaining a solid feel and appearance.

Implementation Method 1

rigid polyisocyanurate/polyurethane foam technology has advanced. Rigid polyisocyanurate/polyurethane foam possesses properties typical of other plastics but also provides superior thermal and acoustical insulating properties

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

rigid polyisocyanurate/polyurethane foam possesses properties typical of other plastics but also provides superior thermal and acoustical insulating properties

Methodology Applied
Scientific EffectAcoustic insulation: Acoustic Absorption

Data Source

PatentEP4589109A1Architectural interior door construction
Publication Date: 2025.07.23 ISOSTRUC LLC
  • EP4589109A1 patent drawingFigure 1~1B
  • EP4589109A1 patent drawingFigure 2
  • EP4589109A1 patent drawingFigure 3~5

AI summary

A door comprising a molded core formed of a rigid foam material, having rigid reinforcing inserts affixed to the molded core.