Movable Valve Member Prevents Plastic Infiltration in Pneumatic Ejection
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Solution Overview
Problem
Dynamic pneumatic valve devices used for ejecting plastic articles from molds face limitations, including potential plastic material infiltration due to movable valve member failures and reduced air jet power, leading to operational inefficiencies and quality issues.
Innovation Solution
A dynamic pneumatic valve device with a movable valve member that automatically moves to an intermediate closing position upon mold closure, utilizing the thrust of the injected plastic material to ensure a tight seal and high air flow, preventing material infiltration and ensuring efficient ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dynamic valve devices are used to enable high air flow for ejection, then the ejection power is improved, but plastic material infiltration occurs when the valve member fails to close properly
Solution Approach 1:
The valve member is designed with a preliminary closing action that occurs before the injection phase. The mold closure pushes the valve member to a preliminary closing position that blocks the air supply duct, preventing plastic material infiltration before injection begins. This preliminary protective action ensures that even if the valve fails during operation, material cannot penetrate the air supply system.
Solution Approach 2:
The system performs a preliminary closing of the valve member during mold closure, before the injection of molten plastic material. This preliminary action positions the valve member to block the air supply duct, ensuring that the duct is sealed and protected before any injection occurs, thereby preventing material infiltration.
2Reliability
If static valves with narrow slits are used to prevent material infiltration, then reliability is improved, but air jet power is reduced due to excessive pressure drop
Solution Approach 1:
The valve member is designed to be movable rather than fixed, transitioning between open and closed positions based on operational requirements. During ejection, the valve opens to allow high air flow; during injection, mold closure pushes it to a closed position to prevent material infiltration. This dynamic behavior resolves the contradiction between maintaining high air flow power and preventing material infiltration.
3Productivity
If the valve member stays in slightly open position due to actuator failure, then plastic material penetrates into the valve device and supply ducts, but continuous operation is required
Solution Approach 1:
The valve member is designed with a preliminary closing action that occurs before the injection phase. The mold closure pushes the valve member to a preliminary closing position that blocks the air supply duct, preventing plastic material infiltration before injection begins. This preliminary protective action ensures that even if the valve fails during operation, material cannot penetrate the air supply system.
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 solution prevents plastic material infiltration and maintains high air flow rates, enhancing the ejection process and reducing operational disruptions and defects in molded articles.
Implementation Method 1
a compression spring positioned between an annular shoulder, inside the valve body, and a rest member fastened to the stem of the movable valve member to urge the movable valve member towards a retracted closing position
Implementation Method 2
the movable valve member is urged into an advanced opening position by the same flow of pressurised air that is injected into the cavity of the mould
Implementation Method 3
advantageously uses the thrust exerted by the same injected plastic material in order to urge the movable valve member from an intermediate closing position towards a fully retracted closing position
Data Source
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AI summary
A pneumatic valve device (17) for ejecting, by pressurised air, moulded articles (16) in plastic material from a cavity of a mould (10, 11); the valve device (17) comprises a valve body (18) havingan air feeding chamber (34) connectable to a pressure air source, and a spring-biased pressure-actuated valve member (20, 21). The valve member comprises a valve head (20) having fore and side surfaces (30, 27), and a stem (21) rearwardly extending from the head (20); an air flow path (32, 33) is provided in the valve member from the rear end of the steam (21) to at least one exit hole (33) on the side surface (27) of the valve head (20). The valve member (20, 21) is axially movable between a retracted position into a seat of the valve body (18), in which closes the flow path (32, 33), and an advanced position in which the valve head (20) protrudes into the cavity of the mould (10, 11). At the closure of the mould (10, 11) in case of failure, the valve head (20) firstly is moved back to an intermediate position by a movable member (11) of the mould (10, 11) into the seat to close the flow path, and then pushed into the fully retracted position by the thrust of the plastic material flowing into an annular space between facing surfaces (13, 30) of the valve head (20) and the movable member (11) of the mould.