3D Printed Foam-Filled Object Production
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Solution Overview
Problem
Existing additive manufacturing processes face challenges in producing complex-shaped foam objects with internal geometries due to the mechanical limitations of 3D printed cases, which often fail under the pressure of rising foam and released propellants, and struggle with reusability and cost-effectiveness of construction materials.
Innovation Solution
A method involving the production of a shell using additive manufacturing, followed by the introduction of a polyisocyanate and polyol reaction mixture that reacts to form a polymer within the shell, allowing for a longer setting time to prevent shell damage and enabling the creation of complex foam structures with mechanical reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a reaction mixture is introduced into a 3D printed shell to produce foam, then complex-shaped foam objects with internal geometries can be produced, but the shell may fail under the pressure of rising foam and released propellants
Solution Approach 1:
The patent changes the chemical parameters of the reaction mixture by using a two-component system (polyisocyanate and polyol) with controlled reactivity ratios. The NCO index is specifically adjusted to balance between reaction speed and pressure generation, allowing the foam to expand slowly enough that the 3D printed shell can withstand the internal pressure while still achieving complete filling and complex geometries.
Solution Approach 2:
The 3D printed shell itself serves as a pre-designed pressure containment structure with optimized wall thickness and geometric reinforcement features. The shell is manufactured beforehand with sufficient mechanical strength to cushion and contain the foam expansion pressure, preventing shell failure while enabling complex internal foam geometries.
2Productivity
If conventional additive manufacturing processes are used to produce foam objects, then production time is reduced, but the construction materials lack reusability and cost-effectiveness
Solution Approach 1:
The unreacted polyol component in the reaction mixture can be recovered and reused in subsequent production cycles. The process allows for partial recovery of raw materials, reducing waste and improving cost-effectiveness while maintaining the rapid production advantages of additive manufacturing.
Solution Approach 2:
The reaction mixture system is designed to allow unreacted components to remain in the shell after foam expansion, which can then be drained and reused. The process automatically provides material recovery capability without requiring additional complex equipment, improving both productivity and material efficiency.
3Productivity
If a fast-reacting reaction mixture is used to fill the shell, then production time is reduced, but the shell is damaged by the rapid pressure increase
Solution Approach 1:
The patent optimizes the reaction kinetics by adjusting the NCO index (ratio of isocyanate to hydroxyl groups) and selecting specific polyisocyanate and polyol components with appropriate reactivity. This creates a balanced reaction rate that is fast enough for practical production but controlled enough to prevent excessive pressure buildup that would damage the shell.
Solution Approach 2:
The foam expansion process is made dynamically controllable through the two-component reaction system. The reaction rate can be adjusted by changing component ratios, temperature, or catalyst concentration, allowing optimization between production speed and shell stress management for different shell designs and applications.
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 allows for the production of complex-shaped foam objects with internal geometries that were previously inaccessible, while reducing production time and enhancing the mechanical properties of the objects, and promoting cost-effective and resource-saving production with reusable materials.
Implementation Method 1
providing a reaction mixture comprising a polyisocyanate component and a polyol component in the volume and allowing the reaction mixture to react in the volume to obtain a polymer present at least partially in the volume
Data Source
Figure 1~3
AI summary
The invention relates to a method for producing an object comprising the the following steps: producing a shell, which surrounds a volume for holding a fluid, by means of an additive manufacturing method from a construction material; providing a reaction mixture comprising a polyisocyanate component and a polyol component in the volume and allowing the reaction mixture to react in the volume such that a polymer present at least partly in the volume is obtained. The reaction mixture has a setting time of ≥ 2 minutes. An object that can be obtained by means of a method according to the invention comprises a shell, which defines a volume located within the shell, and a foam, which completely or partly fills the volume. The shell comprises a thermoplastic polyurethane polymer, the foam comprises a polyurethane foam having a compressive strength at 10% compression (DIN EN 826) of ≥ 50 kPa or a compression hardness at 40% compression (ISO 3386) of ≤ 15 kPa and the foam and the shell are at least partly integrally bonded to each other. The object can be a football, for example.