Monochromatic Infrared Preform Heating System
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Solution Overview
Problem
Current preform heating systems for beverage bottles are inefficient due to high heat dispersion and low energy absorption by plastic materials, leading to energy waste and the need for larger ovens with inadequate temperature homogeneity.
Innovation Solution
A monochromatic infrared radiation heating system that concentrates radiation on individual preforms using a carousel with radially symmetric heating elements and reflecting elements to direct radiation inward, optimized for specific wavelengths absorbed by PET and other polyester or polyolefin resins, reducing heat loss and improving temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If tungsten infrared lamps are used to heat preforms, then the preforms can be heated to the desired temperature, but the energy efficiency is low with no more than 15% of emitted electricity being effectively converted into thermal energy absorbed by the preforms
Solution Approach 1:
The patent changes the wavelength parameter of the radiation source to match the absorption spectrum of PET material. Instead of using broadband tungsten lamps, the invention uses infrared LEDs or laser diodes emitting at specific wavelengths (around 1500-1600 nm) where PET has maximum absorption coefficient, thereby dramatically improving energy absorption efficiency
Solution Approach 2:
The patent applies localized heating by directing radiation precisely at the preform surface rather than using omnidirectional lamp heating. The radiation sources are positioned to concentrate energy on the preform while minimizing dispersion into the environment, creating a localized high-energy zone that improves heating efficiency
2Productivity
If a grid of lamps arranged on a flat surface is used for heating, then the heating system can cover multiple preforms, but the radiation is not homogeneous and the cylindrical geometry of preforms is not properly addressed
Solution Approach 1:
The patent adapts the heating system to the cylindrical geometry of preforms by using radially arranged radiation sources that follow the curved surface. The infrared LEDs or laser diodes are positioned along the cylindrical path of the preform, ensuring uniform radial heating that matches the preform's geometry and eliminates hot or cold spots
Solution Approach 2:
The patent divides the heating system into multiple discrete radiation sources arranged around the preform's path. Each radiation source targets a specific angular position, and their combined effect creates uniform circumferential heating. This segmented approach allows precise control of radiation distribution around the cylindrical preform
3Temperature
If conventional ovens with long preform paths are used to allow adequate heating time, then the preforms can be heated uniformly, but the ovens become of large size and heat dispersion into the environment is high
Solution Approach 1:
The patent replaces the mechanical convection-based heating system with a direct radiation heating system. Instead of relying on hot air circulation and long exposure paths, the invention uses infrared LEDs or laser diodes to deliver energy directly to the preform surface, dramatically reducing the required heating path length and oven volume
Solution Approach 2:
The patent enables rapid heating by using high-intensity monochromatic radiation that is efficiently absorbed by the preform material. The concentrated energy delivery allows the preform to reach the required temperature in a much shorter time and distance, skipping through what would traditionally require a long heating zone
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 system achieves higher energy efficiency, reduced heating time, and improved temperature accuracy, allowing for a more compact design while minimizing energy waste and maintaining production capacity.
Implementation Method 1
a monochromatic source of appropriate wavelength, chosen from those with an absorption coefficient for PET or other polyester or polyolefin resins suitable for appropriate heating of the material
Implementation Method 2
the various plastic materials have energy absorption spectra in rather narrow wavelength ranges
Implementation Method 3
a plurality of external reflecting elements, each of said reflecting elements being configured to radiate a preform radially towards the center and individually from the outside with the radiation part emitted by the corresponding heating element
Data Source
AI summary
The present invention relates to a heating system for preforms upstream of a blowing or stretch-blowing machine, in particular a heating system using monochromatic infrared radiation, preferably laser-generated.In particular, the invention relates to a heating system (301) for preforms (P), comprising a carousel for treating the preforms (P) comprising a plurality of heating elements (304) configured to be inserted either inside or outside each preform (P) and to radiate electromagnetic radiation in the infrared field which forms, in such a device, a disc of radiation according to a radial symmetry which departs from the center of the axis of the preform and which appropriately converges and diverges.