Method for producing foamed moldings
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Solution Overview
Problem
Existing methods for producing foamed moldings, particularly in complex geometries, face challenges with non-uniform foam density distribution due to constant injection quantities, which require specialized nozzles and result in increased conversion costs and downtimes.
Innovation Solution
A process involving the introduction of a foam-forming reaction mixture under constant injection pressure with varying quantities over time, using equal-pressure nozzles and a mixing head with constant-pressure nozzles to ensure consistent mixing and energy supply, allowing for better distribution and reduced flow paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If constant injection quantity is used, then injection process is simple, but foam density distribution becomes non-uniform
Solution Approach 1:
The injection quantity is changed from constant to time-dependent variable, allowing the injection rate to decrease as the mold fills. This dynamic adjustment ensures uniform foam density distribution by adapting the injection rate to the filling stage, resolving the contradiction between manufacturing precision and process simplicity.
2Manufacturing precision
If variable nozzle opening cross-section is used, then foam density distribution improves, but conversion costs and downtimes increase
Solution Approach 1:
Instead of changing the physical structure of the nozzle (opening cross-section), the invention changes the operational parameter (injection quantity over time) to achieve the same effect of uniform foam density. This avoids the need for specialized variable nozzles, eliminating additional conversion costs and downtimes while maintaining manufacturing precision.
3Manufacturing precision
If constant injection pressure is used, then injection control is simple, but flow path distribution becomes unfavorable
Solution Approach 1:
The injection quantity is made time-dependent while maintaining constant pressure, creating a dynamic injection process that improves flow path distribution. The decreasing injection rate over time allows better material distribution throughout the mold cavity, achieving manufacturing precision without increasing device complexity since the pressure control remains simple.
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 approach achieves more homogeneous foam density distribution, improved mechanical properties, and material savings by minimizing shear losses and optimizing flow paths, suitable for complex geometries without the need for variable nozzles.
Implementation Method 1
the foam-forming reaction mixture is obtained from the reaction of a first and a second reaction component
Implementation Method 2
the first and second reaction components are introduced into a comparatively small mixing chamber (2) in the mixing head by means of equal-pressure nozzles (1)
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a method for producing foamed moldings, comprising the steps of providing a mold (1) and introducing a foam-forming reaction mixture (6) into the mold (1), wherein the foam-forming reaction mixture (1) is introduced into the mold (1) under a constant injection pressure and in a quantity that can be changed over time. The introduced quantity of the foam-forming reaction mixture is changed over time by varying the output of a pump motor acting on the reaction mixture.