Multidimensional Rigid Foam Parts Using Jigsaw Interlocking Joints

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Solution Overview

Problem

Existing methods for producing large-volume multidimensional rigid foam parts face issues such as segment slippage, air gaps, and mechanical weak points due to butt joints, leading to structural integrity problems and inefficiencies in milling and thermoforming processes.

Innovation Solution

A process involving thermoforming and milling of planar component segments into jigsaw puzzle-piece shapes, using polymers with a glass transition temperature of at least 100°C, ensures stable connections and prevents slippage, allowing for complex geometries and efficient material utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If butt joints are used to connect core segments for large-volume parts, then the size of the finished core can be increased, but segment slippage and air gaps occur leading to mechanical weak points

Engineering Contradiction:
Improvesize of finished coreVSAvoidstructural integrity
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The core structure is divided into multiple segments that can be assembled together. Each segment is individually milled and then connected through interlocking joints, allowing large-volume parts to be produced while maintaining structural integrity through precise segment positioning and connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple core segments are merged into a single integrated structure through interlocking joints. The segments are designed with complementary connection surfaces that interlock to form a unified core structure, eliminating gaps and ensuring force transmission across the entire component.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If milling is used to produce jigsaw puzzle-piece connections in flexible foams, then precise connections can be achieved, but the foam softens due to frictional heat and cuttings are added

Engineering Contradiction:
Improveconnection precisionVSAvoidfoam temperature
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The patent replaces traditional mechanical milling with a combination of thermoforming and precision cutting. The foam is first thermoformed to create the basic geometry, then precision cutting is used to create the jigsaw puzzle-piece connections, avoiding the frictional heat generation of conventional milling while maintaining connection precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the processing parameters by using thermoforming at controlled temperatures followed by precision cutting. This parameter change allows the foam to be shaped and connected without generating excessive frictional heat that would cause softening, while still achieving precise jigsaw puzzle-piece connections.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If cooling by coolant and lubricant is applied during milling, then frictional heat can be reduced, but the porous structure of the foam prevents easy removal of coolants and lubricants

Engineering Contradiction:
Improvefrictional heatVSAvoidcoolant removal
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The patent replaces the coolant-based cooling system with an alternative approach using controlled thermoforming temperatures and precision cutting. This eliminates the need for coolants and lubricants in the milling process, avoiding the problem of coolant accumulation in the porous foam structure while still controlling temperature to prevent foam softening.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 process enables stable, cost-effective production of large-volume rigid foam parts with variable dimensions, preventing slippage and ensuring homogeneous force transmission, suitable for complex structures like aircraft components and sandwich materials.

Implementation Method 1

the planar component segments are shaped multidimensionally by thermoforming

Methodology Applied
Scientific EffectThermoforming: Heat Treatment

Implementation Method 2

the multidimensionally shaped component segments are milled into jigsaw puzzle-piece shapes, the multidimensional component segments are assembled to give a multidimensional rigid foam part

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentUS20250332778A1Process for producing multidimensional rigid foam parts by means of jigsaw puzzle-piece connection
Publication Date: 2025.10.30 EVONIK OPERATIONS GMBH

AI summary

The invention relates to a process for producing multidimensional rigid foam parts.