Retaining Pin Plunger Mechanism for Preform Cooling and Ejection
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Solution Overview
Problem
Current post-mold cooling technologies for injection molded articles face challenges in efficiently retaining and cooling preforms, particularly in maintaining vacuum force and ensuring proper ejection, which can lead to sticking and inadequate cooling.
Innovation Solution
A retaining pin system with a plunger mechanism that moves between advanced and retracted positions, allowing for fluid communication between a suction source and the preform's interior, utilizing a biasing member to maintain vacuum force and facilitate cooling, while inhibiting fluid flow when not in use to prevent sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retaining pin system with plunger mechanism is used to retain preforms, then vacuum force is maintained and preforms are securely retained, but the system complexity increases due to multiple moving parts
Solution Approach 1:
The retaining pin system is divided into separate functional components: a body portion with a suction channel, a plunger with a plunger channel, and a biasing member. This segmentation allows each component to perform its specific function independently while maintaining overall system reliability through coordinated operation of the segmented parts.
Solution Approach 2:
The plunger is nested within the body portion of the retaining pin, with the plunger channel positioned inside the suction channel. The biasing member is nested within the body portion, occupying the space between the plunger and the body wall. This nesting arrangement reduces overall system complexity by eliminating the need for separate housings while maintaining all necessary functions.
2Temperature
If the plunger is kept in the retracted position to maintain fluid communication for cooling, then cooling efficiency is improved, but vacuum force is lost causing preforms to detach
Solution Approach 1:
The plunger alternates between retracted and advanced positions in periodic cycles: retracted during the cooling phase to allow fluid communication, and advanced during the retention phase to block the channel and maintain vacuum. This periodic action resolves the contradiction by providing the desired cooling efficiency during specific time intervals while maintaining retention reliability during other intervals.
Solution Approach 2:
The plunger is designed to be movable rather than fixed, allowing it to dynamically change position between retracted and advanced states. This dynamic capability enables the system to adapt to different operational requirements (cooling vs. retention) at different times, resolving the contradiction between cooling efficiency and retention reliability.
3Speed
If air pressure is used to eject preforms from cooling tubes, then ejection speed is improved, but preforms may stick to tubes due to inadequate vacuum venting
Solution Approach 1:
The plunger is advanced to block the suction channel before air pressure is applied for ejection. This preliminary action of blocking the vacuum source prevents vacuum lock that would otherwise resist the ejection force, ensuring reliable and speedy ejection of preforms from the cooling tubes.
Solution Approach 2:
The system uses pneumatic pressure (air pressure) applied through the plunger to eject preforms. By controlling the timing of plunger advancement to block the vacuum channel just before air pressure application, the system achieves both high ejection speed and reliable ejection by eliminating vacuum adhesion forces.
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
Effectively retains and cools preforms by maintaining a vacuum force and ensuring efficient ejection, preventing sticking and enhancing cooling efficiency through controlled fluid flow.
Implementation Method 1
The proximal opening is for fluid communication with a suction source. The body flow channel and the plunger flow channel are in fluid communication when the plunger is in the retracted position
Implementation Method 2
utilizing a biasing member to maintain vacuum force and facilitate cooling, while inhibiting fluid flow when not in use to prevent sticking
Data Source
AI summary
A retaining pin for handling injection molded preforms includes a body including an internal body flow channel, and a plunger coupled to the body and movable relative to the body between advanced and retracted positions. The plunger includes an internal plunger flow channel. The plunger further includes a plunger abutment surface directed away from the body. The plunger is biased toward the advanced position and movable to the retracted position by engagement of the plunger abutment surface with an inner surface of a closed end of a preform when the preform and retaining pin are moved toward each other. The body flow channel and the plunger flow channel are in fluid communication when the plunger is in the retracted position. Fluid communication between the plunger flow channel and the body flow channel is inhibited when the plunger is in the advanced position.