Composite Molding Resin Flow Control
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Solution Overview
Problem
Existing molding methods for composite materials, such as RTM, result in surface irregularities due to resin shrinkage differences between the resin and reinforcing base materials, leading to poor appearance quality, especially in automobile parts like roofs and hoods.
Innovation Solution
A molding method involving prepreg sheets where a first reinforcing base material is impregnated with a first resin for the base layer and a second reinforcing base material with a higher amount of second resin is used for the surface layer, ensuring the second resin is in excess, preventing resin flow and fiber disturbance during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dry base material intermediate layer is used to prevent resin flow, then surface irregularities are reduced, but resin flows toward the intermediate layer causing fiber disturbance and internal voids
Solution Approach 1:
A resin-impregnated intermediate layer is introduced between the base layer and surface layer to act as a mediator. This intermediate layer has resin content between that of the base layer and surface layer, preventing resin from the surface layer from flowing toward the base layer during curing, thereby eliminating both surface irregularities and internal voids while maintaining fiber alignment.
Solution Approach 2:
The resin content of the intermediate layer is specifically controlled to be between the resin content of the base layer and the resin content of the surface layer. This parameter optimization prevents excessive resin flow from the surface layer to the base layer during curing, resolving the contradiction between surface flatness and internal quality.
2Ease of manufacture
If RTM molding method is used with resin injection, then molding is achieved, but resin flow causes disturbance in reinforcing fibers
Solution Approach 1:
The intermediate layer is pre-impregnated with resin before the molding process. This preliminary action ensures that when resin is injected during RTM molding, it does not cause excessive flow toward the base layer, thereby maintaining fiber alignment while enabling successful molding.
3Reliability
If metal mold temperature is high for molding, then curing is achieved, but resin immediately melts and flows toward intermediate layer
Solution Approach 1:
The intermediate layer with moderate resin content serves as a cushioning layer that absorbs and controls resin flow during high-temperature molding. This beforehand cushioning prevents resin from the surface layer from flowing toward the base layer, maintaining both curing completion and surface quality.
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 effectively eliminates surface irregularities, improves appearance quality, and maintains the strength of the composite material by preventing resin flow and fiber disturbance, thus enhancing the composite material's appearance and durability.
Implementation Method 1
when the resin with which the intermediate layer is impregnated is cured and shrinks
Implementation Method 2
the first prepreg sheet and the second prepreg sheet, which are stacked, are heated and cured
Data Source
AI summary
A molding method is provided for manufacturing a composite material having a base layer formed of at least one first prepreg sheet and a second prepreg sheet stacked on at least a portion of the first prepreg sheet. The first prepreg sheet and the second prepreg sheet are stacked, and then heated and cured. The second prepreg sheet constitutes a front surface layer that is integrally formed on the surface of the base layer. Here, the amount of second resin in the second prepreg sheet is larger than the amount of first resin in the first prepreg sheet on a per unit volume basis in an interface between the first prepreg sheet and the second prepreg sheet when the second prepreg sheet is stacked on the first prepreg sheet.