| Titre : |
A method to model web trajectory and release in forward roll coating |
| Type de document : |
texte imprimé |
| Auteurs : |
Harrison Gates, Auteur ; Douglas W. Bousfield, Auteur |
| Année de publication : |
2017 |
| Article en page(s) : |
p. 957-964 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Enduction au rouleau
Lubrification
Modèles mathématiques
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
The trajectory of the web at the exit of a roll coating operation can influence the quality of the final coating. While methods to model the web trajectory have been given in the literature, these methods are limited in various ways. A method is proposed to describe the web trajectory and the pressure distribution in the fluid at the exit of a forward roll coater. The Reynolds lubrication equations for the fluid are coupled with the web by a force balance on web node points. The fluid pressure in the coating layer generates forces on the web. These forces deflect the web. Integration in time gives the web dynamics. The angle that the web is pulled from the nip and the tension are found to influence the pressure pulse in the divergent section of the nip to a large extent. Low tensions lead to a second pressure pulse followed by a sub-ambient or tack pressure. Pulling the web at various angles from the nip can cause the tack pressure to increase or decrease. Pressure pulses are predicted that are comparable to measurements by a laboratory device. |
| Note de contenu : |
- Fig. 1. Configuration at the exit of a forward roll coating nip. The web can deform before the coating layer splits. a is the takeoff angle of the web, and xp is the distance away from the nip that this point is applied. The center of the nip is taken as x = 0
- Fig. 2. Experimental device to measure the influence of a web on the nip dynamics. The rubber-covered roll is to the left of the steel roll on the right. In normal operation, the rubber-covered roll would be in contact with the steel roll and rotates in the clockwise direction
- Fig. 3. Dimensionless pressure distribution predicted when the web is pulled straight from the nip for various tensions for h*i = 0:01 and x*p = 2.0. On the right, the case for T* = 10 by itself for clarity
- Fig. 4. Web trajectories for various tensions when the web is pulled straight from the nip for various tensions and x*p = 2. Note that the y-axis is enlarged compared to the x axis
- Fig. 5. Dimensionless pressure distribution for even lower web tensions for the same conditions as in Fig. 2
- Fig. 6. Results for positive (downward) takeoff angle of 20°, with the take-up point being x*p = 2.0 for h* i = 0.01. Pressure profiles are shown on the left. Web trajectories on the right. Note that at T* = 100, the web follows the top roll surface some distance
- Fig. 7. Same as Fig. 5, but for a negative angle of 20°, with the web being pulled upward from the nip. Left side is the pressure distribution, and the right side is the web trajectories
- Fig. 8. Measured pressure distribution in a laboratory device that had a tensioned web |
| DOI : |
10.1007/s11998-017-9938-1 |
| En ligne : |
https://link.springer.com/content/pdf/10.1007%2Fs11998-017-9938-1.pdf |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29124 |
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 14, N° 5 (09/2017) . - p. 957-964
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A method to model web trajectory and release in forward roll coating in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 14, N° 5 (09/2017)
