Composite Door Inner Panel Side Frame Strength in Narrow Window Frames
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Solution Overview
Problem
Existing methods for manufacturing automobile door inner panels face challenges in maintaining mechanical strength in side frames extending in a vertical direction due to issues with fiber orientation and deviation during injection molding, particularly when using composite materials with continuous fibers or resin-impregnated reinforcing members.
Innovation Solution
A method involving the integration of a composite material with reinforcing fibers dispersed in-plane and an injection-molding material, using a mold with specific gates for injecting the materials, ensuring the composite material forms a skin layer on the door inner panel, and incorporating metal fittings through insert molding to enhance mechanical strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous fiber reinforced plastic is used for side frames, then mechanical strength is improved, but fiber orientation control becomes difficult
Solution Approach 1:
The side frame is divided into two distinct regions: a skin layer containing continuous fibers for strength, and a bulk layer with dispersed short fibers for ease of molding. This segmentation allows each region to have optimized properties without compromising the other.
Solution Approach 2:
Different fiber configurations are applied to different parts of the side frame. The skin layer uses continuous fibers aligned in the vertical direction for maximum strength, while the bulk layer uses randomly dispersed short fibers for manufacturability.
2Strength
If prepreg with continuous fibers aligned in one direction is used, then mechanical strength is improved, but positioning precision requirement increases
Solution Approach 1:
The continuous fiber prepreg is segmented into a thin skin layer that is molded separately from the bulk material. This reduces the amount of precise positioning required while maintaining the strength benefits of continuous fibers in the critical surface region.
3Ease of manufacture
If injection-molding material with short fibers is used, then ease of molding is improved, but mechanical strength deteriorates
Solution Approach 1:
Short fibers are used in the bulk layer where high strength is not critical, allowing for easy molding. The strength requirements are met by the continuous fiber skin layer, creating a complementary division of functional requirements.
4Strength
If resin-impregnated reinforcing member sheet is used, then mechanical strength is improved, but deviation sensitivity increases
Solution Approach 1:
The reinforcing members are segmented into short dispersed fibers in the bulk layer rather than continuous aligned fibers in a sheet. This reduces sensitivity to positioning deviations while maintaining reinforcement benefits through the skin layer's continuous fibers.
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
The method ensures desired mechanical strength is achieved in the side frames, simplifies the manufacturing process, and improves shape followability by minimizing the impact of slight material deviations, resulting in a high-quality door inner panel.
Implementation Method 1
injecting the injection-molding material Y into the mold
Implementation Method 2
pressing the composite material X and the injection-molding material Y in the mold to integrally mold the door inner panel
Data Source
AI summary
Provided are a door inner panel manufacturing method and a door inner panel with which it is possible to ensure the mechanical strength of a side frame that extends in a vertical direction in a relatively narrow region serving as a window frame. This door inner panel manufacturing method is a method for manufacturing a door inner panel that includes a side frame which extends in a vertical direction and which is molded integrally using a composite material X including reinforcing fibers dispersed in an in-plane direction, and an injection molding material Y, the manufacturing method including the following steps (1) to (4): (1) a step for arranging the composite material X on a molding fixed die; (2) a step for lowering a molding moveable die to cause the molding moveable die to come into contact with the composite material X; (3) a step for injecting the injection molding material Y into a molding die; and (4) a step for pressing the composite material X and the injection molding material Y inside the molding die to integrally mold the door inner panel.