Sequential Injection Molding of Transparent Plastic Plates
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Solution Overview
Problem
Traditional injection molding of large transparent plastic plates with non-transparent areas faces challenges such as aesthetic and optical defects, residual internal stresses, and material waste due to the limitations of film-injection systems, which cannot ensure high-quality production with minimal stress and optimal mechanical properties.
Innovation Solution
A process involving sequential injection of transparent plastic material with the mold half-open to distribute pressure uniformly, followed by compression and overmolding of non-transparent material to cover injection indicators, reducing internal stresses and enhancing optical and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If film-injection system is used for large transparent plastic plates, then production efficiency is improved, but internal stresses increase and optical quality deteriorates
Solution Approach 1:
The injection process is divided into multiple sequential phases: first injecting transparent material with mold half-open, then closing mold and injecting non-transparent material, allowing each phase to optimize for its specific function while maintaining overall production efficiency
Solution Approach 2:
The mold state is changed from fully closed to half-open during injection, and injection parameters (pressure, flow rate) are dynamically adjusted between phases to minimize internal stresses while maintaining high production efficiency
2Loss of substance
If conventional injection molding is used for large transparent plates, then material waste is reduced, but residual internal stresses increase
Solution Approach 1:
The mold is opened half-way during injection to allow material to distribute uniformly before closing, preventing excessive pressure buildup and reducing internal stresses while maintaining material efficiency
Solution Approach 2:
The injection process uses periodic action with distinct phases (half-open injection, closed mold injection, compression) to control material flow and pressure distribution, minimizing both waste and internal stresses
3Stress or pressure
If sequential injection with mold half-open is used, then internal stresses are reduced, but process complexity increases
Solution Approach 1:
The same molding apparatus performs multiple functions: injecting transparent material, closing mold, injecting non-transparent material, and compression molding, eliminating the need for separate operations and reducing overall process complexity despite the sequential nature
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 process enables the efficient production of high-quality, stress-free bi-component plastic plates with optimal optical and mechanical properties by minimizing internal stresses and eliminating injection indicators, thus overcoming the limitations of conventional molding systems.
Implementation Method 1
injecting the transparent plastic material within said mould in the first moulding station via first said set of injectors according to a sequential modality with the mould half-open so as to distribute uniformly the pressure
Implementation Method 2
injecting the non-transparent plastic material within said mould in the second moulding station via said set of second injectors so as to overmould said peripheral edge on said peripheral area of the transparent plate
Data Source
AI summary
Described herein is a process for the production of plates made of plastic material by means of sequential injection with the mould half-open and a subsequent step of compression obtained by closing the mould.