Blowmolding Demolding Unit for Polypropylene Container Chains
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Solution Overview
Problem
The use of polypropylene for blowmolded container products poses challenges due to its higher processing temperature and stiffer surface finish, making demolding difficult, especially at high cycle frequencies, and existing solutions do not ensure efficient demolding processes.
Innovation Solution
A demolding unit with a power drive that deflects the container chain into a back-and-forth movement and oscillatory motion, using a driver arrangement with bearing surfaces to transfer deflection forces, facilitating separation from the mold walls even at high cycle frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polypropylene material is used for blowmolded container products, then higher autoclaving temperature (121°C) and sterility requirements can be satisfied, but demolding becomes difficult due to higher processing temperature and stiffer surface finish
Solution Approach 1:
The patent applies mechanical vibration through a demolding unit that generates oscillatory movements of the mold halves during the demolding process. This vibration reduces the adhesion between the polypropylene container surface and the mold walls, enabling efficient separation despite the material's inherently stiff surface finish and high processing temperature that normally cause strong adhesion.
2Reliability
If polypropylene material is used with higher processing temperatures, then sterility is improved, but demolding efficiency decreases at high cycle frequencies
Solution Approach 1:
The patent implements periodic action by applying oscillatory movements at specific frequencies during the demolding phase. This periodic mechanical stimulation creates repeated cycles of adhesion and separation, ensuring that containers are reliably released from the mold walls even at high production cycle frequencies, thereby maintaining both sterility and productivity.
3Ease of manufacture
If polyethylene material is used, then easier processing and demolding are achieved, but higher processing temperatures required for autoclaving (121°C) cannot be met
Solution Approach 1:
The patent changes the material parameter from polyethylene to polypropylene, which has a higher melting point and can withstand autoclaving temperatures of 121°C. To compensate for the resulting demolding difficulties, the patent introduces additional process parameters including vibration frequency and amplitude control in the demolding unit, enabling the system to achieve both high-temperature sterilization capability and efficient demolding.
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
Ensures reliable and efficient separation of containers from the mold walls, allowing for the use of polypropylene materials at higher temperatures and higher production frequencies, overcoming the demolding difficulties associated with polypropylene.
Implementation Method 1
The driver arrangement can have a passage channel with the wall sections forming a skirt for the moving container chain as well as the bearing surfaces for the transfer of the deflection forces to the container chain.
Implementation Method 2
As a result of this procedure, the containers experience an elastic contraction that in turn is designed to facilitate the separation of the containers from the walls of the mold.
Data Source
AI summary
A device for producing blowmolded container products (11) from plastic material, using single mold parts (7) movable along a production line (5) and in pairs toward one another and away from one another to close or open a production mold. The container products (11) are molded and exit after the demolding procedure in the form of a container chain (9) moved along the production line (5). A demolding unit (3) engages the exiting container chain (9) outside the production mold to support the demolding procedure. The demolding unit (3) has a force drive (17) deflecting the container chain (9) out of the production line (5) into back and forth movement.