Compression Mould Segmentation for Sandwich Structure Forming
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Solution Overview
Problem
Existing methods for producing three-dimensionally shaped sandwich structures face challenges in reducing cracks, tears, or breaks in the core layer during moulding, especially when forming complex shapes, which affects the mechanical properties of the final product.
Innovation Solution
The process involves using a compression mould with movable mould parts, where the first mould part deep-draws the core layer to form wrinkles, and the second mould part moves more slowly to enhance wrinkle formation, reducing cracks and allowing the core material to be compressed without affecting the final shape. The core layer is covered with a mouldable material, which can be applied before or after moulding, and reinforced with fibrous materials to improve mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a compressible core layer is used to maintain covering material near the surface, then the sandwich structure achieves good mechanical properties and lightweight characteristics, but the core layer is difficult to mould into complex three-dimensional shapes without cracking
Solution Approach 1:
The first mould section is divided into multiple movable mould parts that can move independently relative to each other. This segmentation allows different regions of the core layer to be deep-drawn at different rates, preventing cracks while forming complex three-dimensional shapes. The covering layer is applied in segments corresponding to these movable parts, enabling staged formation of the sandwich structure.
Solution Approach 2:
The covering layer is applied to the core layer before the deep-drawing process begins. This preliminary action ensures that the covering material is already positioned near the surface throughout the forming process, maintaining mechanical properties while the core layer is gradually shaped into complex forms through staged deep-drawing of the mould parts.
2Productivity
If the first mould part moves quickly to deep-draw the core layer, then complex three-dimensional shapes are formed efficiently, but cracks and tears occur in the core layer
Solution Approach 1:
The mould parts are designed to move dynamically at different rates during the deep-drawing process. The first mould part moves quickly to achieve high productivity, while the second mould part moves more slowly to prevent cracking. This dynamic, differential movement allows the system to simultaneously achieve both high forming speed and core layer integrity.
3Strength
If covering material is applied before moulding to maintain it near the surface, then mechanical properties are improved, but more covering material is required increasing weight
Solution Approach 1:
The covering layer is applied to specific regions of the core layer corresponding to the movable mould parts, rather than uniformly across the entire surface. This partial application is sufficient to maintain covering material near the surface during deep-drawing and achieve the required mechanical properties, while using less material than a complete uniform coating would require, thereby reducing weight.
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 approach reduces the formation of cracks and tears in the core layer, enhancing the mechanical properties of the sandwich structure while allowing for complex three-dimensional shapes, and reduces the amount of covering material required, resulting in a lightweight, strong, and dimensionally stable product.
Implementation Method 1
bringing the mould sections into their moulding position to mould said core layer into a three-dimensional shape between the first and the second mould surfaces
Implementation Method 2
a first portion of the core layer is deep-drawn by moving the first mould part towards its moulding position so that wrinkles are formed in the core layer
Data Source
AI summary
The three-dimensionally shaped sandwich structure is produced starting from a layered material (1) comprising a compressible core layer, in particular a paper honeycomb structure, having two opposite main faces which are each covered with a reinforcing material and with a mouldable material. The layered material (1) is moulded in a compression mould comprising two mutually movable mould sections (7, 9). In order to reduce the formation of cracks, tears or breaks in the core layer, the first mould section (7) is composed of at least two mutually movable mould parts (10 and 11-12). A first portion of the layered material (1) is first deep-drawn by moving the first mould part (10) towards its moulding position so that wrinkles are formed in the layered material and the second mould part (11-12) is moved later and/or more slowly than the first mould part (10) towards its moulding position. In this way the formation of wrinkles by the first mould part (10) is enhanced due to the fact that the layered material (1) is little or not hampered from being drawn by the first mould part to the deep-drawn area. The second mould part may be composed of different subparts (11-13) which are also moved successively towards their moulding position.