Dry Thermoplastic Prepreg for Robotic CMC Preform Thermoforming
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Solution Overview
Problem
The preforming process for ceramic matrix composites (CMCs) is costly due to high labor requirements, particularly in subprocesses like prepregging, cutting, and layup, which are not well-suited for automation.
Innovation Solution
Development of a fibrous textile-based thermoplastic prepreg with controlled solvent content, enabling robotic handling and thermoforming into desired molds, using polyvinyl butyral (PVB) as the thermoplastic resin and ethanol as the solvent, which can be evaporated to create a dry, rigid prepreg suitable for automated processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional wet prepreg processes are used, then material flexibility and ease of handling are improved, but automation compatibility deteriorates due to high labor requirements and touch labor intensity
Solution Approach 1:
The patent changes the solvent content parameter from traditional high levels (30-50 wt%) to a controlled low level (0-10 wt%), creating a semi-dry or dry prepreg state that maintains handling characteristics while enabling automation compatibility for robotic pick-and-place operations
Solution Approach 2:
The patent uses a specific thermoplastic resin mixture with polyvinyl butyral as an intermediary binding agent that provides sufficient adhesion for automated handling while allowing the prepreg to be processed in a semi-dry state that is compatible with robotic operations
2Stability of the object's composition
If high solvent content is used in prepreg, then fiber impregnation and resin distribution are improved, but manufacturing complexity increases due to additional debulking and solvent removal steps
Solution Approach 1:
The patent extracts and removes the solvent early in the process to create a semi-dry or dry prepreg state, eliminating the need for subsequent debulking and solvent removal steps while maintaining adequate resin distribution through controlled initial impregnation
Solution Approach 2:
The patent performs solvent removal as a preliminary action before layup and curing, creating a dry or semi-dry prepreg that requires no further debulking or solvent removal during the manufacturing process, thereby simplifying subsequent steps
3Productivity
If automated pick-and-place systems are implemented, then labor costs are reduced, but material handling requirements become more stringent due to dependence on prepreg handling characteristics
Solution Approach 1:
The patent modifies the prepreg physical state by reducing solvent content to create a semi-dry or dry condition that provides adequate rigidity for robotic manipulation while maintaining ease of handling through controlled thermoplastic resin content and composition
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
Facilitates fully or partially automated preforming and thermoforming processes, reducing costs, improving throughput, and maintaining consistent CMC microstructures by minimizing tow spreading and fiber distortion, while allowing for complex part production.
Implementation Method 1
removing the solvent from the combined fibrous textile with a thermoplastic resin mixture wherein the remaining wt% of solvent is less than 5%
Implementation Method 2
The stack of prepreg plies may be joined together by intermingling of the PVB resin of adjacent prepreg plies in the stack
Implementation Method 3
molding the at least one dry prepreg ply by applying heat and pressure to the at least one dry prepreg ply within the mold form at least until the dry prepreg adopts the predetermined interior shape of the mold form
Data Source
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AI summary
A dry prepreg (50) of fibrous textile (10)/thermoplastic (20) with handling characteristics highly compatible with robotic handling and a method for making at least one dry prepreg (50) and forming the at least one dry prepreg (50) over a mold form. The method also includes using the at least one molded dry prepreg (50) as at least one sub-laminate in a thermoforming process. The methods include CMC preforming processes which can be automated though the use of robotic handling devices (150).