Extruded Composite Stiffened Panel Co-Molding Process
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Solution Overview
Problem
Existing techniques for producing stiffened panels made of thermosetting composite materials are lengthy, require costly and specific molds, and struggle with accuracy and surface finish, especially when using composite materials.
Innovation Solution
A method involving the use of strips of fibers impregnated with non-hardened resin, which are shaped and positioned using a die and then polymerized under pressure and temperature in a heating press, allowing for accurate joining and continuous production of stiffened panels with improved accuracy and surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stiffeners are independently produced and joined to skin using bonding or riveting, then joining strength is achieved, but production time increases and manufacturing cost increases
Solution Approach 1:
The patent merges the production of skin and stiffeners into a single co-molding process. Strips forming the skin and stiffeners are placed in contact within a mold cavity, and both are molded simultaneously in their non-hardened state, then hardened together through polymerization. This eliminates separate joining operations (bonding or riveting) while maintaining structural integrity, thereby reducing production time and manufacturing cost.
2Shape
If skin is produced first and stiffeners are produced on skin in second step, then surface finish is improved, but positioning accuracy of stiffeners deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-positioning both skin strips and stiffener strips in their correct relative positions within the mold cavity before the molding process begins. The strips are arranged and fixed in the non-hardened state, ensuring accurate positioning is established beforehand. This preliminary positioning is then maintained throughout the simultaneous molding and hardening process, achieving both good surface finish and high positioning accuracy.
3Productivity
If cocuring technique is used to simultaneously mold and harden skin and stiffeners, then joining efficiency is improved, but mold complexity increases
Solution Approach 1:
The patent segments the mold into a first mold part and a second mold part, with each part having specific shaping functions. The first mold part shapes the skin while the second mold part shapes the stiffeners. This segmentation allows for simpler, more specialized mold components rather than a single complex monolithic mold, facilitating easier manufacturing, assembly, and maintenance of the molding system.
4Manufacturing precision
If strips are pulled through die for shaping and positioning, then manufacturing accuracy is improved, but process complexity increases
Solution Approach 1:
The die serves multiple functions: it shapes the strips, positions them relative to each other, and maintains their configuration during the molding process. This multi-functional die simplifies the overall process by combining several operations (shaping, positioning, and alignment) into a single tool, reducing process complexity while maintaining high manufacturing accuracy.
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 mitigates the defects of existing techniques by enabling efficient, accurate, and cost-effective production of stiffened panels with improved surface finish and dimensional control, allowing for the production of parts with desired mechanical properties.
Implementation Method 1
a pressure P and a temperature T for polymerizing the resin of the first and second strips being applied to the preform in the heating press
Data Source
AI summary
A method for producing a part made of a composite material, including a skin and at least one stiffener made of strips, which are in turn made of one or more plies of fibers impregnated with a non-polymerized resin. The method includes the steps of: producing a preform of the part by pulling the strips through a die for shaping and positioning the skin and the stiffeners, a polymerization core being provided between a first strip and a second strip prior to the passage thereof through the die; and pressing the resulting preform in a hot press for a duration dt while applying a pressure P and at a temperature T for polymerizing the resin of the strips in the hot press over a pressing length L that is shorter than the length of the panel.