Plastic Preform Concave Body for Uniform Infrared Heating
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Solution Overview
Problem
Existing preforms made of plastic materials, such as PET, experience zones of overheating when exposed to monochromatic or quasi-monochromatic infrared radiation, leading to uneven heating during the blow molding or stretch blow molding process, which cannot be effectively overcome by adjusting the energy distribution of the radiation sources.
Innovation Solution
A preform design with specific geometric characteristics, including a concave portion and varying wall thickness, is proposed to minimize refraction and promote uniform heating, along with a method involving heating using monochromatic or quasi-monochromatic infrared radiation followed by blow molding or stretch blow molding within a mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If monochromatic or quasi-monochromatic infrared radiation is used for heating preforms, then service life and directivity of heating sources are improved, but zones of overheating occur in the preform material
Solution Approach 1:
The preform incorporates a concave portion with specific geometric parameters (depth between 0.5C and 0.95C, radius of curvature between 1.5C and 10C) that creates localized variations in material distribution. This local structural modification alters the refraction pattern of infrared radiation, directing energy more uniformly through the preform body and preventing concentration of thermal energy in specific zones, thereby resolving the overheating problem while maintaining the advantages of monochromatic radiation sources
Solution Approach 2:
The invention changes the geometric parameters of the preform body by introducing a concave portion with specifically controlled dimensions. The depth of the concave portion (0.5C≤C′≤0.95C) and its radius of curvature (1.5C≤RE≤10C) are optimized to control the refraction of infrared radiation. This parameter modification transforms the heating pattern from non-uniform with overheating zones to uniformly distributed thermal energy across the preform
2Use of energy by moving object
If conventional preform geometry is used with monochromatic radiation, then heating efficiency is improved, but refraction causes uneven heating and overheating zones
Solution Approach 1:
The concave portion introduces localized structural variation in the preform body, creating specific refraction pathways for infrared radiation. This local geometric feature (with depth 0.5C≤C′≤0.95C and radius 1.5C≤RE≤10C) distributes radiation energy more evenly through the material, preventing the formation of overheating zones while preserving overall heating efficiency
Solution Approach 2:
The concave portion with controlled radius of curvature (1.5C≤RE≤10C) utilizes curved geometry to manipulate the refraction of infrared radiation. The specific curvature profile transforms the radiation path through the preform, ensuring uniform energy distribution and eliminating the refraction-related heating non-uniformity that occurs with conventional cylindrical preform geometries
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 preform design ensures improved thermal uniformity and reduced risk of overheating, allowing for more controlled and efficient heating processes, resulting in higher quality container manufacturing with minimized refraction and optimized energy distribution.
Implementation Method 1
noted in the preforms is the existence of zones of overheating of the material, which even a fine adjustment of the energy distribution of the sources does not make it possible to overcome
Implementation Method 2
heating the body and the bottom of the preform to a temperature greater than the glass transition temperature of the material... by exposure to a monochromatic or quasi-monochromatic infrared radiation
Data Source
AI summary
Disclosed is a container perform made from plastic material, including: a body; an open neck that extends from the body from which it is separated by a radially projecting flange; a bottom that closes the body opposite the neck; the body having a concave portion in axial cross section, where: B≤0.9·A 0.5.C≤C′≤0.95.C in which A is the overall diameter of the body, measured below the flange; B is the outer diameter of the bottom, measured at the junction of same with the body; C is the cumulative height of the body and the bottom, measured from the flange; C′ is the height, measured axially, of the concave portion of the body, and the concave portion has, in axial cross-section, on an outer surface, an outer radius of curvature RE such that: 1.5.0≤RE≤10.C