Blown Film Heating Roller for Optical Quality
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Solution Overview
Problem
Blown film systems face challenges in achieving optical film quality comparable to cast films due to slow cooling of the ascending tubular film, leading to a cloudy and less glossy film surface, and require high installation heights to manage the cooling process effectively.
Innovation Solution
A blown film system with a treatment roller section equipped with heating means above the pair of take-off rollers to heat the double-layer film web, allowing for further mechanical processing without the need for extensive cooling and energy-intensive reheating, thereby improving film quality and reducing system height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tubular film is allowed to cool slowly during ascent, then the film can be handled more easily, but the optical quality deteriorates becoming cloudy and less glossy
Solution Approach 1:
The patent applies preliminary cooling action by introducing compressed air into the tubular film during its ascent through the cooling zone. This preliminary cooling allows the film to reach a handleable temperature before reaching the take-off rollers, while the timing and duration of cooling are controlled to prevent excessive cooling that would degrade optical quality. The compressed air cooling is applied at the optimal moment during the film's ascent.
2Force
If the film is cooled quickly to enable sufficient force application with squeeze rollers, then mechanical processing is improved, but the installation height increases
Solution Approach 1:
The patent employs pneumatic cooling by introducing compressed air into the tubular film during its ascent. This pneumatic cooling system provides rapid and controlled cooling of the film, enabling the squeeze rollers to apply sufficient force for effective mechanical processing. The compressed air cooling achieves the required cooling rate within a compact vertical space, avoiding the need for excessive installation height.
3Stability of the object's composition
If the film is cooled extensively before mechanical processing, then the film structure stabilizes, but energy is consumed for subsequent reheating
Solution Approach 1:
The patent applies partial cooling action rather than extensive cooling. The compressed air is introduced into the tubular film during ascent to provide just sufficient cooling for structural stabilization and handleability, but not to the extent that would require subsequent reheating. This partial cooling approach balances film structure stabilization with energy efficiency by avoiding over-cooling.
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 solution enables the production of films with improved optical quality and reduced energy consumption by maintaining the film at a processable temperature for mechanical interventions, such as stretching, while minimizing system height and operational costs.
Implementation Method 1
a treatment roller section with heating means for the double-layer film web is provided above the pair of take-off rollers
Implementation Method 2
Cooling of the melt is achieved at a tolerable distance from the annular die by means of an active coolant for the ascending film tube
Implementation Method 3
compressed air is introduced into the interior of the film tube. This leads to transverse stretching of the film tube
Data Source
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AI summary
For a blown-film installation, providing longitudinal stretching of the produced double-layer film web after the haul-off, more precisely after the reversing unit and before the winder, is known. Performing stretching on the film guided downward is also known, wherein then the film must be preheated because of the long cooling path from the haul-off. In addition, performing control of the blown film, in such a way that a film thickness that is as uniform as possible results after drawing out, is known. In a first aspect, the invention proposes that the film is heated above the haul-off and then mechanically treated. The film can thereby be brought to an easy-to-process temperature level from first heat by means of only little energy. In a second aspect, the invention proposes that a horizontally oriented treatment roller segment is provided between the haul-off and a reversing device arranged above the haul-off. In both aspects, the control should be used in order to achieve a uniform film thickness after the drawing out.