Heatable Vacuum Hood for Composite Curing
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Solution Overview
Problem
Existing vacuum hood devices face challenges in achieving a precise fit and multiple usability, particularly in shaping complex contours, and lack direct temperature control during the vacuum pressing process, which affects the curing of composite substrates.
Innovation Solution
A vacuum hood device made of elastic plastic material with an integrated electrical heating system, allowing temperature adjustment between 20° C and 200° C, using a carbon fiber cord as the heating element, and featuring a sealing wedge for gas-tight sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing foil and sealing cord are used to shield the shaped body, then gas-tight sealing can be achieved, but manual sealing work requires great deal of material and time, and exact attachment to strongly pronounced concave/convex contours is particularly difficult
Solution Approach 1:
The patent employs disposable sealing foils that are discarded after a single use. These foils are pre-cut to match the contour of the shaped body, eliminating the need for manual sealing work. The foil is simply placed over the shaped body and secured with a sealing cord, achieving gas-tight sealing without requiring skilled manual labor or extensive sealing time.
Solution Approach 2:
The sealing foils are pre-formed and pre-cut to match the specific contours of the shaped body before use. This preliminary preparation of the sealing surface allows for easy attachment and ensures proper fit on complex geometries without requiring manual adjustment or skilled craftsmanship during the sealing process.
2Adaptability or versatility
If vacuum hoods made of elastic plastic material are used for multiple usability and perfect fit, then gas-tight covering and multiple use are achieved, but direct temperature control of the composite substrate is not possible during the vacuum pressing process
Solution Approach 1:
The patent introduces an intermediary heating element in the form of a heating foil that is placed between the vacuum hood and the composite substrate. This heating foil serves as a mediator that transfers thermal energy from the vacuum hood to the composite substrate, enabling temperature control while maintaining the gas-tight sealing function of the elastic plastic vacuum hood.
Solution Approach 2:
The vacuum hood system combines multiple materials with different functions: an elastic plastic material for gas-tight sealing and formability, and a heating foil (typically a thin metallic or ceramic material) for thermal control. This composite structure allows the vacuum hood to simultaneously provide mechanical sealing and thermal management functions.
3Object-generated harmful factors
If the composite substrate is pressed at room temperature, then the initial viscous state is maintained, but outgassing and curing process is slower and less effective
Solution Approach 1:
The patent applies preliminary heating to the composite substrate before and during the initial stages of vacuum pressing. By raising the temperature in advance, the curing process is accelerated and gas bubbles are expelled more effectively from the composite material, preparing it for optimal consolidation before the final pressing stage.
Solution Approach 2:
The patent dynamically changes the temperature parameter during the vacuum pressing process. The heating system adjusts the temperature profile through different stages: initial heating to remove volatiles and bubbles, followed by controlled cooling or maintenance at optimal curing temperature. This parameter variation optimizes both outgassing and curing efficiency.
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 solution enhances the outgassing and curing process of composite substrates by controlling temperature, improving viscosity and enabling precise temperature management for efficient curing, even on complex shapes.
Implementation Method 1
the temperature of which can be adjusted by means of an electrical heating device... the heating device is designed to set the temperature of the vacuum hood to a value between 20° C. and 200° C.... the electrical conductor can be formed, for example, from a mesh of thin metal wires or from one or more carbon fiber threads
Implementation Method 2
a workpiece designed as a shaped body is usually shielded from the ambient atmosphere or evacuated by means of a sealing foil and a sealing cord... placed under vacuum pressure... the pressing out and outgassing of air or gas bubbles trapped in the curable composite substrate to be pressed is improved and accelerated
Implementation Method 3
the vacuum hood is made of an elastic plastic material... vacuum hoods that fit perfectly and can be used multiple times are known in the prior art and are made of an elastic plastic material
Implementation Method 4
a layer of a curable composite substrate applied to a solid shaped body containing a fibrous structure and a matrix of a curable viscous filling material introduced into the fibrous structure... the process of curing a composite substrate can be started by specifically setting a predetermined initial temperature
Data Source
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AI summary
With a vacuum hood device (100), comprising a vacuum hood (110), for providing gas-tight covering during a pressing process performed by means of gas pressure on a layer of a curable composite substrate applied to a solid moulded body and including a fibrous structure and a matrix of a curable viscous filling material introduced into the fibrous structure, influencing the temperature of the material to be pressed during a vacuum pressing operation is made possible by the vacuum hood (110) being produced from a flexible plastics material of which the temperature can be set by means of an electrical heating device (120).