Resin Part Movable Insert Pressure Application
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In injection molding and injection-compression molding of optical parts, non-uniform resin pressure and temperature distribution lead to figure accuracy issues, causing minute distortions and sink marks, which can result in image distortion in head-up displays and misrecognition in laser-type image detection units.
Innovation Solution
A resin part with a plate-shaped molded main body where a surface opposite to the high-accuracy surface is used as a pressure-application surface, with a parting line positioned such that (t/4)≤x≤(3t/2) from the end edge, where x is the distance to the parting line and t is the thickness, to ensure uniform resin pressure and prevent sink marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a movable insert is used to apply pressure during injection-compression molding, then sink marks are suppressed and figure accuracy is improved, but the complexity of the molding apparatus increases
Solution Approach 1:
The movable insert is positioned in advance at a predetermined location before resin injection, and pressure is applied during the molding process to compensate for volume shrinkage. This preliminary positioning and continuous pressure application prevents sink marks from forming, thereby improving figure accuracy without requiring complex post-processing
Solution Approach 2:
The movable insert applies pressure locally at the bottom surface of the molded product, specifically targeting areas prone to sink marks. By concentrating pressure application at the parting line region rather than uniformly across the entire mold, the system achieves high figure accuracy while maintaining relatively simple apparatus design
2Productivity
If resin is injection-filled into the metal mold, then the molded product is formed efficiently, but non-uniform pressure distribution causes figure distortion and sink marks
Solution Approach 1:
The movable insert is pre-positioned at the bottom surface before resin injection begins. As resin is injection-filled, the movable insert immediately applies compensating pressure to counteract volume shrinkage, ensuring uniform pressure distribution throughout the molding process. This prevents both sink marks and figure distortion while maintaining high molding efficiency
Solution Approach 2:
The system dynamically adjusts pressure parameters during the molding process by moving the insert to apply supplemental pressure. The pressure application timing and magnitude are optimized to match the resin cooling and shrinkage characteristics, transforming the pressure distribution from non-uniform to uniform, thereby eliminating figure distortion while preserving productivity
3Manufacturing precision
If the movable insert is positioned away from the resin flow path, then transcription accuracy is improved, but sink marks occur at low-accuracy locations
Solution Approach 1:
The parting line created by the movable insert, which initially appears as a potential defect location, is strategically positioned and designed to serve as the pressure application zone. By applying pressure at the parting line on the bottom surface, the system converts this location into a beneficial region that prevents sink marks throughout the entire molded product, including areas with low transcription accuracy requirements
4Manufacturing precision
If pressure is applied uniformly across the entire mold surface, then figure accuracy is improved, but the molding apparatus becomes more complex
Solution Approach 1:
Instead of applying pressure uniformly across the entire mold surface, the movable insert concentrates pressure application at the bottom surface and parting line region. This localized pressure application is sufficient to prevent sink marks and ensure figure accuracy, thereby achieving the desired manufacturing precision while keeping the apparatus design simple and cost-effective
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 configuration suppresses sink marks and ensures high transcription accuracy by maintaining uniform resin pressure and reducing internal stress at the outer-peripheral end portions, achieving improved figure accuracy and productivity.
Implementation Method 1
an insert for forming part of a transcription surface in a metal mold is configured as a movable insert; and the movable insert advances to supplement pressure against the volume shrinkage due to the cooling of resin filled in the metal mold
Implementation Method 2
a resin material molten by heating is injection-filled into the metal mold and then solidified by cooling
Data Source
AI summary
A resin part includes a plate-shaped molded main body that is constituted of an injection-molded product. Of plate surfaces of the molded main body, a surface on an opposite side to a surface requiring surface accuracy constitutes a pressure-application surface to which pressure is applied by a movable insert. A parting line is formed on the pressure-application surface by the movable insert to satisfy the following relationship: (t/4)≤x≤(3t/2), where x is a distance from an end edge part of the molded main body to the parting line and t is a thickness of the molded main body.