Analysis Of Common Problems Of Press Felt

1. Have you ever meet felt lint in the process of using press felt?

• The simplest form of press felt lint is that the fibers adhere to the surface of the paper sheet. Thereare many reasons for the damage and the lint of the felt, mainly two of which are scraped by machine parts and chemical damage. The most common is that the surface of the press felt tornloosened by high pressure water.Sometimes the responsibility is not with the fabric, because thefibers can also come from pulp or even from outside systems.

• Lack of lubricating water between the vacuum box cover and the felt, which causes the temperaturerise and the fiber is damaged.

  Solution: for paper machine especially middle speed or high speed paper machine, the rational useof lubricating water now only benefit to the clean degree of the blanket but also produce a waterfilm between the vacuum panel and blanket which play a role as a lubrication, sealing and coolingeffect.

• Supporting roller surface with burrs, iron molds , the roller surface wrapped with slurry, orexpander roller rubber thread stand is too high or stand has obvious edges and corners,no sharp edges exists between eight openings and rubber roller body or the high and low transition zone istoo short, etc are likely to cause blanket abrasion.

  Solution: All supporting roller surfaces should be smooth without burrs and rust, and copper rollers, stainless steel rollers and rubber rollers are options. Expander roller spiral rubber strip standgeneral height is 8 ~ 15 mm, rubber sets of 20 ~ 40 mm wide, rubber machine without edges,bevelling should be smooth,opening Angle is 600 ~1200, and the transition of the starting point ofthe figure of eight openings should be clearly slope.

2.After using the felt, is there embossing on your paper surface?

• Embossing is a multifaceted problem, and the following may cause embossing (the most common disease of embossed paper is toilet paper)

  The dispersant star is too large, the vacuum suction is insufficient, there are too many impurities in the pulp, and the water pressure is insufficient.

  The supporting rod is installed incorrectly

  The density of the base cloth of the woolen cloth is too high, or the structure of the base cloth does not move, and the density is not -

  felt embossing will occur if the wool mesh is too heavy and the fiber thickness is not matched properly.

• When the felt is embossed due to the blockage, how can we accurately find the embossing point? At this time, we should first pull off the pulp, slow down the speed, turn on the water pipe, turn on the vacuum, stop the water pipe after the felt is cleaned, turn on the vacuum for a few more turns and stop. When the wool cloth is dry, you can see that the embossing point of the wool cloth is white, and then pick out the blockage with a needle, On the reverse side of the embossing point of the woolen cloth, we can try to cut several weft threads and pay attention to "three to five" so that the embossing is finished.

3.Is your press felt deformed after use?

It is mainly caused by the looseness and unstable structure of the base cloth in the production of woolen cloth.

Method: put the public tight blanket Kun and let the wool cloth run in a relaxed state. The above standard thread is incorrect, which is unfavorable to the normal operation of wool cloth.

4.Standard line deviation or front and rear bending deformation?

• a. There are several problems with the deviation of the standard line. The length of both sides of the wool cloth itself is not the same.

• b. The stick axes of the paper machine are not parallel, resulting in different tightness of the wool cloth.

• c. After shutdown, the wool cloth is watered unevenly when it is newly opened, resulting in inconsistent shrinkage of wool cloth.

• d. Analysis and treatment of front and back bending deformation of standard line

When the standard line bulges in the running direction of the paper machine, it is mainly caused by the excessive middle height of the supporting wheel. The first treatment method is to grind the middle height and the second is to add pressure to the supporting roller.

The backward of the standard line is mainly caused by the insufficient medium height of tuokun, or the medium height is correct but the pressure is too large, the concave phenomenon of the standard line will also appear.