Thick-Walled Plastic Preform Layer Segmentation for Cycle Time Reduction
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Solution Overview
Problem
Existing methods for producing thick-walled plastic preforms for large-volume containers, such as 5-gallon water bottles, are inefficient due to long cycle times, which hinder high output rates and increased material usage.
Innovation Solution
The method involves dividing the thick-walled preform into multiple layers with similar layer thicknesses, allowing for simultaneous production using multi-component injection molding technology, where each layer is produced in a separate cavity with slight thickness variations to optimize cooling rates and reduce cycle time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick-walled plastic preform is produced as a single layer, then the wall thickness requirement is met, but the cycle time becomes excessively long
Solution Approach 1:
The thick-walled preform is divided into multiple layers with similar thicknesses (e.g., three layers of approximately 3mm each to achieve a total wall thickness of 9mm). Each layer can be produced and cooled independently in separate cavities, significantly reducing the overall cycle time compared to producing a single thick-walled preform
2Productivity
If multi-component injection molding technology is used to produce multiple layers simultaneously, then productivity increases, but device complexity increases
Solution Approach 1:
The production process transitions from a single-cavity mold to a multi-cavity mold arrangement where each cavity produces a separate layer. The mold system includes multiple cavities positioned to receive material from injection units, allowing simultaneous production of multiple layers in different spatial locations
Solution Approach 2:
The injection molding machine is equipped with multiple injection units or a multi-component injection system that can simultaneously inject material into multiple cavities. The mold system is designed to accommodate multiple cavities of different shapes and sizes, making it versatile for producing different preform configurations
3Loss of time
If each layer is produced in a separate cavity with slight thickness variations, then cooling efficiency improves and cycle time reduces, but manufacturing precision control becomes more challenging
Solution Approach 1:
Each cavity is designed with specific dimensional characteristics tailored to the requirements of the layer it produces. The mold cavities can have different shapes and sizes optimized for their respective layers, allowing each layer to cool efficiently while maintaining the required thickness tolerances for the final preform assembly
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 approach significantly reduces the cycle time for producing thick-walled preforms, enabling faster production of large-volume containers with minimal material waste and efficient use of resources, while allowing for the use of different materials for each layer to optimize costs and performance.
Implementation Method 1
a plasticizing and injection unit (9) which is designed to simultaneously fill at least two, preferably at least three, cavities (7a, 7b, 7c) with a plastic material (M)
Implementation Method 2
a closing unit (5) with a fixed mold half (5b) and a movable mold half (5a), which, when closed, form cavities (7a, 7b, 7c) of different shapes and sizes for forming the different layers (1a, 1b, 1c) of the plastic preform (1)
Data Source
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AI summary
A plastics parison (preform) (1) for an inflatable large-volume container is described, in particular for a container with capacity of at least 5 litres, preferably at least 10 litres, where the plastics parison has a closure region and an inflatable hollow body region. In order to reduce cycle time, the invention proposes that the preform, or at least the inflatable hollow body region thereof, is composed of a plurality of layers (1a, 1b, 1c), where the thickness of each layer is at least 2 mm, preferably at least 3 mm, and where the thickness of the individual layers (1a, 1b, 1c) is in essence identical. Multicomponent injection moulding technology can thus be used with the rotating table technique or with the indexing plate technique to produce the various layers simultaneously in a plurality of injection units in such a way as to give, after each shot, a finished thick-walled preform (1). Also described are a process for producing the plastics parison (1) and an injection moulding machine.