Sandwich Component Curing with Charging Gas Pressure
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Solution Overview
Problem
The production of sandwich components with open core structures and cover layers formed from curable plastic materials often results in sink marks due to internal pressure changes during curing, requiring elaborate surface reworking and potentially impaired mechanical connections between layers, especially in aircraft interior components.
Innovation Solution
Introducing a charging gas, such as nitrogen or air, into the core structure before partial solidification of the cover layers, with controlled pressure to prevent sink marks, and using a press or autoclave with temperature and pressure control to ensure optimal bonding and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sandwich component is cured at elevated temperature and pressure, then the curing process is completed successfully, but sink marks form on the cover layers due to internal pressure changes
Solution Approach 1:
A charging gas is introduced into the core structure before and/or during the curing process to create internal pressure that counteracts the negative pressure developing during cooling. This preliminary counter-pressure prevents the cover layers from sinking into the core structure, eliminating sink marks while maintaining successful curing.
Solution Approach 2:
A charging gas (such as nitrogen or air) is used as an intermediary substance introduced into the core structure to mediate between the internal pressure changes and the cover layers. The gas provides controlled pressure to prevent sink marks without interfering with the curing chemistry of the plastic material.
2Manufacturing precision
If elaborate surface reworking is performed to ensure adequate surface quality, then surface defects are removed, but production time and complexity increase
Solution Approach 1:
The charging gas pressure is applied during the curing process to prevent sink marks from forming in the first place. This preliminary preventive action eliminates the need for subsequent surface reworking operations such as grinding and levelling, thereby maintaining high surface quality while improving production efficiency.
3Ease of manufacture
If the curable plastic material changes viscosity during curing, then the material flows to fill the mold, but internal pressure changes cause sink marks
Solution Approach 1:
The charging gas provides counter-pressure during the viscosity change and cooling phases to prevent the cover layers from sinking, while still allowing the material to flow and fill the mold during the initial curing phase when viscosity is lower.
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 produces sandwich components with nearly optimal surface characteristics, eliminating the need for mechanical reworking and enhancing the bonding between layers, thereby improving the quality and efficiency of the production process.
Implementation Method 1
a charging gas, in particular nitrogen or air, is introduced to the core structure prior to at least partial solidification of the cover layers, wherein a charging gas pressure is selected that is less than or equal to an operating pressure of the closed device
Implementation Method 2
the curable plastic material contained in the cover layers changes its viscosity during the curing process
Implementation Method 3
two press areas that are temperature-controllable by means of at least one heater
Data Source
AI summary
The invention relates to a method for the production of sandwich components with an open core structure and a cover layer applied to each side, wherein the cover layers are formed with a curable plastic material, and the sandwich component is cured in a closed device under pressure. A charging gas, which may be nitrogen or air, is introduced to the core structure prior to at least partial solidification of the cover layers, wherein a charging gas pressure p Charging gas is selected that is less than or equal to an operating pressure p operating of the closed device in order to, in particular, at least largely prevent the formation of sink marks in the cover layers. Furthermore, the invention relates to a press for implementing the method.