FRP Structural Body Molding with Deformable Core and Staged Curing
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Solution Overview
Problem
Existing methods for manufacturing fiber-reinforced plastic (FRP) structural bodies with modified or polygonal cross-sections face issues such as appearance defects like wrinkles, voids, and resin-rich areas due to non-conformity of reinforcing fibers with shape changes during molding, and require costly large-scale equipment and complex core removal processes.
Innovation Solution
A method involving winding composite materials around a core, compressing, preheating to partial resin cure, and molding to achieve desired cross-sectional shapes, allowing for integrated laminate bodies with high freedom and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a collapsed core and prepreg are arranged in a molding die and molded under pressure, then modified cross-section or polygonal cross-section structural bodies can be obtained, but appearance defects such as wrinkles, voids, and resin rich areas occur due to non-conformity of reinforcing fibers with shape changes
Solution Approach 1:
The patent applies preliminary action by pre-forming the cylindrical laminate body with the desired cross-sectional shape before final molding. The prepreg is wrapped around a mandrel to create a preformed body that already has the target cross-section, eliminating the need for complex shape changes during molding and preventing appearance defects
Solution Approach 2:
The manufacturing process is segmented into distinct stages: preforming the laminate body around a mandrel, then molding the preformed body in a separate step. This segmentation allows each stage to be optimized independently, ensuring both shape accuracy and appearance quality
2Shape
If resin is injected into a molding die while pressurizing a hollow core, then FRP structural bodies with modified or polygonal cross-sections can be molded, but large-scale equipment and high costs are required
Solution Approach 1:
The patent inverts the conventional approach by instead of injecting resin into a hollow core to form the shape, it forms the shape first by wrapping prepreg around a mandrel, then molds the preformed solid body. This inversion eliminates the need for complex resin injection equipment while achieving the same cross-sectional shapes
3Shape
If the molding die has a complex shape, then arbitrary cross-sectional shapes can be formed, but stable placement of prepreg becomes difficult and resin rich or voids occur at corner portions
Solution Approach 1:
The patent performs the difficult shaping operation in advance by wrapping the prepreg around a mandrel to create a preformed body with the target cross-section. This preliminary action transfers the complexity from the molding die to the simple cylindrical mandrel, making prepreg placement easy and uniform while achieving complex final shapes
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 enables high-quality, cost-effective production of FRP structural bodies with complex cross-sections, minimizing defects and reducing equipment costs by using a deformable core and controlled resin curing.
Implementation Method 1
heating and curing the laminate body so that a curing level of the thermosetting resin is 30 to 90％ in a state prior to complete curing
Implementation Method 2
pressurizing the laminate body to deform the cylindrical core member to a non-circular cross-sectional shape
Implementation Method 3
heating the laminate body until the thermosetting resin is completely cured
Data Source
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AI summary
Provided are a method for manufacturing a structural body and a structural body, the structural body formed of FRP and having a high degree of freedom in cross-sectional shape even at a low cost. The method for manufacturing a structural body includes a winding step of forming a cylindrical laminate body LM by winding a plurality of composite materials including reinforcing fibers and an uncured thermosetting resin around a hollow cylindrical core member CY; a compressing step of winding a tape or film around an outer circumference of the laminate body LM and compressing the same; a preheating step of heating the laminate body LM until a state prior to complete curing of the thermosetting resin; and a main heating step of arranging the laminate body LM around which the tape or film is wound and the cylindrical core member in a molding die and pressing the same to thereby heat the laminate body LM until the thermosetting resin is completely cured while deforming the cylindrical core member CY to a non-circular cross-sectional shape. Thereby, a structural body in which the cylindrical core member CY and the laminate body LM are integrated can be formed.