Composite Preform Pre-Consolidation for Injection Molding
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Solution Overview
Problem
Existing injection molding processes for composite materials often result in defects such as thread misalignment and deformation due to high injection pressures, especially when using thermoplastic resins, which affect the mechanical properties of the final part.
Innovation Solution
A process where the fibrous preform is consolidated prior to resin injection, using a consolidation resin that can be integrated during weaving, dusted as powder, or applied as a coating, and then processed in a consolidation tool to achieve solidification, reducing porosity and improving handling and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high injection pressure is used to inject thermoplastic resin, then the resin can properly impregnate the preform, but defects such as thread misalignment and interlaminar deformation occur
Solution Approach 1:
The preform is consolidated before resin injection by heating the tool to melt the consolidation resin within the preform, then cooling to solidify it. This preliminary consolidation action strengthens the preform structure before it undergoes the high-pressure resin injection process, preventing thread misalignment and interlaminar deformation while maintaining reliable resin impregnation
2Ease of manufacture
If thermoplastic resin with additives is used to reduce viscosity, then injection is easier, but defects are amplified due to high injection pressures
Solution Approach 1:
The consolidation step performed before resin injection strengthens the preform structure through melting and solidifying the consolidation resin. This preliminary strengthening prevents the amplification of defects during high-pressure injection, maintaining both ease of manufacture and preform dimensional stability
3Productivity
If the preform is not consolidated before injection, then the process is simpler and faster, but mechanical property homogeneity is reduced
Solution Approach 1:
The consolidation step is integrated into the manufacturing cycle by placing consolidating resin within the preform before injection molding. The preform is consolidated in-situ in the injection mold by heating and cooling cycles, eliminating transfer operations and maintaining mechanical property homogeneity while preserving productivity
Solution Approach 2:
The consolidation step and resin injection step are merged into a single integrated process. The preform is consolidated and then immediately injected with resin in the same mold without transfer, combining two operations into one continuous manufacturing cycle that maintains both productivity and precision
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 pre-consolidation step enhances the homogeneity of mechanical properties and reduces deformation during resin injection, leading to improved quality and reduced manufacturing time by eliminating the need for preform transfer.
Implementation Method 1
heating the consolidation tool to the melting temperature of the consolidation resin present inside the fiber preform
Implementation Method 2
solidifying the consolidation resin
Data Source
Figure 1
AI summary
The invention relates to a method for injection molding a part made of a composite material including a fibrous reinforcement densified by a die, the method including, in sequence, the placement of a fibrous preform in an injection mold (E10-1), the pressurized injection of a thermoplastic resin into the mold such as to impregnate the preform (E10-2) and the polymerization of the resin (E10-3), the fibrous preform being consolidated in the injection mold prior to the injection of the resin.