Laser Cleaning of Circulating Fabric in Paper Machines
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Solution Overview
Problem
Existing methods for cleaning circulating fabric webs in paper or board machines, such as those using brushes, water, compressed air, or dry ice, result in high mechanical wear and environmental impact, and are inefficient in removing stubborn deposits like 'stickies' that cause uneven drying.
Innovation Solution
A method utilizing a laser beam to irradiate and evaporate dirt particles from the fabric web, with the laser beam being partially absorbed or scattered to minimize heat transfer and prevent damage to the fabric, and guided through a pipeline system with mirrors to maintain cleanliness and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods (brushes, water, compressed air, dry ice) are used, then the fabric web can be cleaned, but high mechanical wear occurs and maintenance is required frequently
Solution Approach 1:
The patent replaces mechanical cleaning systems (brushes, nozzles, dry ice delivery mechanisms) with a laser-based cleaning system. The laser beam directly removes deposits through ablation without mechanical contact, eliminating wear on cleaning components and removing the need for frequent maintenance of mechanical parts.
Solution Approach 2:
The patent changes the physical state and properties of the cleaning agent from mechanical forms (solid brushes, liquid water, gaseous compressed air) to coherent light energy. By adjusting laser parameters such as wavelength, pulse duration, and power, the system optimizes cleaning effectiveness while minimizing thermal damage to the fabric web.
2Reliability
If conventional cleaning methods are used, then cleaning can be performed, but environmental impact increases due to water consumption and waste
Solution Approach 1:
The laser cleaning system eliminates the need for water and chemical cleaners used in conventional methods. The only byproduct is vaporized deposit material, which can be captured by a suction device, significantly reducing environmental impact and waste disposal requirements.
Solution Approach 2:
The patent implements a suction device that captures and removes vaporized deposit particles and any loose debris during the cleaning process. This prevents contamination of the environment and allows for potential recovery or proper disposal of the removed contaminants.
3Productivity
If laser beam energy is increased to improve cleaning effectiveness, then deposits are removed more effectively, but risk of fabric damage increases
Solution Approach 1:
The patent exploits the different optical properties of the fabric material and deposit materials. By selecting a laser wavelength that is strongly absorbed by the deposits (such as organic stickies) but transmitted or reflected by the fabric, the system achieves selective removal of contaminants without heating or damaging the underlying fabric structure.
Solution Approach 2:
The laser operates in pulsed mode rather than continuous wave, delivering high peak power in short bursts followed by cooling periods. This allows effective ablation of deposits while preventing heat accumulation that could damage the fabric, maintaining a safe temperature differential between the deposit and fabric.
4Reliability
If mechanical cleaning systems are used, then cleaning can be performed, but regular maintenance and higher operational costs are required
Solution Approach 1:
The laser cleaning system has no moving parts in the cleaning head, eliminating wear on brushes, seals, and mechanical components. The only maintenance required is for the laser source itself and the suction device, significantly reducing maintenance frequency and operational downtime compared to mechanical cleaning systems.
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
Reduces mechanical wear and environmental impact, allowing for more frequent maintenance and effective removal of deposits with lower energy absorption by the fabric, ensuring even drying and reduced operational costs.
Implementation Method 1
the laser beam is at least partially absorbed by the dirt particles, so that the dirt particles heat up and evaporate due to the energy of the laser beam
Implementation Method 2
the dirt particles heat up and evaporate due to the energy of the laser beam
Implementation Method 3
the plastic at least partially scatters the laser beam. This is advantageous because it also prevents localized heating of the web of fabric
Data Source
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AI summary
The method for cleaning a fabric sheet in a paper or cardboard machine, comprises transporting a raw paper sheet through the fabric sheet by the paper or cardboard machine, and cleaning the fabric sheet by irradiating with a laser beam, which includes a beam wavelength. The fabric sheet consists of a plastic or metal. The plastic is transparent to the laser wavelength. The plastic partially scatters the laser beam. The laser beam includes laser energy and the plastic absorbs less than 5% of the laser energy. The fabric sheet rotates in a first direction through guide rollers. The method for cleaning a fabric sheet in a paper or cardboard machine, comprises transporting a raw paper sheet through the fabric sheet by the paper or cardboard machine, and cleaning the fabric sheet by irradiating with a laser beam, which includes a beam wavelength. The fabric sheet consists of a plastic or metal. The plastic is transparent to the laser wavelength. The plastic partially scatters the laser beam. The laser beam includes laser energy and the plastic absorbs less than 5% of the laser energy. The fabric sheet rotates in a first direction through guide rollers in the paper or cardboard machine and the laser beam is guided in a second direction of the fabric sheet. The first and second directions include an angle. The fabric sheet transported to the raw paper sheet on a first path in the first direction and recycled on a second path, to the outlet of the first path. The fabric sheet is irradiated with the laser beam at a guide roller on the second path. The cleaning of a circulating fabric sheet is carried out in such a way that impurities on the fabric sheet is partially absorbed and vaporized by the energy of the laser beam. The circulating fabric sheet is a filter belt of the paper or cardboard machine. The laser beam is directed to the fabric sheet through a pipe system with mirrors. A laser is directed to the fabric sheet through an optical fiber. The laser beam is widened before the fabric sheet. A pulsed laser beam generates the laser in a first mode and a continuous laser beam in a second mode. The parameters, depending on the fabric sheet and the impurities, adjusted on the fabric sheet are: the mode of the laser; the intensity or energy of the laser beam; the degree of expansion of the laser beam; the speed of the laser beam in the second direction; and the angle between laser beam and the fabric sheet. Independent claims are included for: (1) a filter belt for a paper or cardboard machine; (2) a device for cleaning a fabric sheet in a first surrounding direction, in a paper or cardboard machine; and (3) a paper or cardboard machine.