Views: 0 Author: Site Editor Publish Time: 2021-02-25 Origin: Site
Calenders are mainly divided into hard calenders and soft calenders. In printing, hard calenders and soft calenders have the following advantages:
Due to the knowledge of the calender, the soft roll surface material rebounds, so that the roll surface can adapt to any poor uniformity and quantitative changes of the paper. The thinner area of the paper is in contact with the heat roller, and for the thicker area, the thickness will not be greatly reduced. Such thick and thin areas can increase its fine smoothness and eliminate stains.
1. Improve the bulk of the paper and maintain the stability of stiffness.
2. Good printing ink absorption
3. The stability of soft calendering and the wide adjustment range of line pressure can be adapted to calender finishing required by different paper types.
4. Because the fiber is not strongly squeezed, the paper strength is good, which improves the operation rate of social equipment.
Because the tightness of the paper is the same, and the thickness reduction is not great, the oil-absorbing film of the pressed paper is good and uniform.
5 .The pressed paper has the same tightness
Calender rolls with higher modulus of elasticity are generally 50 to 500 times softer than steel rolls. When the elastic roll is pressed to a hard roll or cold-quenched cast iron roll with a certain line, its nip width becomes larger than that of steel. -The steel rollers are much wider when they are in contact. The peak pressure decreases with the reciprocal of the nip width, the contact surface is no longer a flat surface, and along the radius of curvature of the steel roll, the total radial compression deformation of the steel roll is small (0.2% to 2%).
In the steel nip, if there are uneven patches in the sheet, the pressure is not uniform. When there are too many thick plaques or flocs in the paper entering the nip, the pressure will reach the maximum here, and the surrounding area will be relatively low. The overall result is that the high fiber density area of the paper web will appear in the low fiber density area of the same sheet thickness, and the latter will receive a lower nip pressure impact. When the paper is pressed in the calender roller of the elastic surface layer, the depth of the depression of the hard roller pressed into the surface layer is large enough so that the change of the thickness of the paper will not change the peak pressure much (peak pressure is the center line of the nip The highest pressure).
6. Even if the paper is not well formed, its opacity can be improved and stains can be eliminated.
7. High smoothness can be obtained and the difference between two sides can be eliminated.
8 .It is possible to make the finished product have higher moisture.