Compression Moulding Annular Forming Element for Preform Leakage
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Solution Overview
Problem
Existing compression moulding apparatuses for forming container preforms often experience undesired leaks of plastics during the moulding process, leading to visible flashes and microscopic defects like microcracks in the finished preforms, which can result in defects in the subsequent bottles.
Innovation Solution
The introduction of an annular forming element that allows the forming chamber to be closed early, reducing the risk of plastic leaks and facilitating the shaping and evacuation of gases, while also aiding in the detachment of the preform from the mould.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mould closes completely before shaping the preform, then the forming chamber volume is reduced, but plastics may leak between the movable parts and punch during the closing process
Solution Approach 1:
The forming chamber closing process is divided into two independent stages: first the annular forming element closes to seal the chamber, then the punch closes to shape the preform. This segmentation prevents plastics leakage by ensuring the chamber is sealed before the punch interacts with the plastics dose.
Solution Approach 2:
The annular forming element performs the preliminary action of closing and sealing the forming chamber before the punch begins its closing motion. This preliminary sealing action prevents plastics from leaking during the subsequent punch closing phase.
2Quantity of substance
If the dose of plastics has great mass to occupy significant volume, then the preform can be fully formed, but the plastics are pushed upwards and can exit the gap between movable parts and punch
Solution Approach 1:
The forming process is segmented into two phases: first the annular forming element compresses the plastics dose within the sealed chamber, then the punch completes the shaping. This prevents overflow by maintaining chamber closure throughout the compression process.
Solution Approach 2:
The annular forming element provides beforehand cushioning by sealing the forming chamber before the punch compresses the plastics. This prevents the plastics from being pushed out of the gap between movable parts and punch during compression.
3Device complexity
If the mould uses traditional closing mechanism, then the structure is simpler, but visible flashes and microcracks form on the finished preform
Solution Approach 1:
The mould structure is segmented into two independent closing mechanisms: an annular forming element for chamber closure and a punch for preform shaping. This segmentation eliminates visible flashes and microcracks by preventing plastics leakage during the closing process.
Solution Approach 2:
The annular forming element acts as an intermediary component that seals the forming chamber between the movable parts and punch. This intermediary sealing element prevents plastics from leaking and forming defects on the preform surface.
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 solution effectively reduces the occurrence of leaks and defects in the preform, resulting in higher-quality container preforms with reduced visible flashes and microcracks, thereby improving the consistency and reliability of the bottle production process.
Implementation Method 1
forming a preform (1) from a dose (68) of plastics by compression moulding
Implementation Method 2
the plastics remain for a sufficient time to ensure stabilisation and an initial and partial cooling of the preform
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An apparatus comprises a punch arrangement (12) and a die arrangement (13) that are opposite one another and closable for defining a forming chamber (70) in which an object (1) can be compression-moulded from a dose (68) of plastics, a punch (14) included in said punch arrangement (12) and two parts (20) that are mutually movable for forming a portion (4) of said object (1) provided with undercuts. Said punch arrangement (12) comprises annular forming means (41) for forming an edge zone (10) of said object (1), said annular forming means (41) and said punch (14) being mutually movable whilst said dose (68) fills said forming chamber (70).