Do You Know About Sealing Strips of Suction Press Roll?

Application of Sealing Strips In The Paper Industry

In the paper making industry, sealing strip is important component commonly used to seal both sides of the vacuum box inside a vacuum roll, forming a sealed area between the roll body and the vacuum box to ensure the stable operation of the vacuum system. Vacuum suction press rolls are one of the most expensive rolls in paper machines, and the cost of ordering spare rolls, stopping and replacing rolls due to the use of sealing strips is enormous, including production losses, replacement of sealing strips, and power consumption.

Suction Press Roll Sealing Strip Contact Sealing Technology

A sealing device must be used for good sealing between the vacuum box and the inner wall of the cylinder, as shown in Figure 1, which mainly consists of sealing grooves, sealing strips, elastic devices, and other components.

Suction Press Roll Sealing Strip Non-contact Sealing Technology

In order to reduce the power consumption and operating noise of the suction press roll, and to extend the service life of the sealing strip as much as possible. The basic principle of non-contact sealing technology for suction press roll sealing strips is that there are one air tube at the bottom and one on the side of the sealing strip. The air tube at the bottom of the sealing strip can be called a "pressurized air tube", and the pneumatic air tube on the side of the sealing strip is called a "locked air tube". When in use, the "pressurized air tube" is first inflated to make the sealing strip contact the inner wall of the roll, then the "locked air tube" is inflated and the "pressurized air tube" is depressurized. Through a special design structure, the sealing strip is slightly lowered and positioned, creating a small gap between the sealing strip and the inner wall of the roll, ensuring the vacuum degree of the vacuum box while avoiding wear of the sealing strip. Due to the presence of vibration, after a period of use, the sealing strip may fall, causing the gap between the sealing strip and the cylinder to increase, which affects the vacuum degree of the vacuum box and decreases. At this point, through an automatic detection and control system, the "pressurized air tube" and "locked air tube" are activated again, restoring the gap between the sealing strip and the inner wall of the cylinder to the set state. Repeat this process to ensure the sealing of the sealing strip.

This technology can significantly extend the lifespan of the sealing strip, as well as significantly reduce power consumption and operating noise. However, the complex structure and frequent lifting of the sealing strip can still cause wear and tear, and the sealing strip still needs to be replaced regularly.

Critical Contact Sealing Technology for Vacuum Roller Sealing Strips

As shown in Figure 2, its structure mainly consists of sealing groove, sealing strip, and rubber tire. Both the sealing strip and the rubber air tube are installed in the sealing groove. The sealing strip is installed on the upper part of the rubber air tube, and the upper part of the sealing strip contacts the inner wall of the roller cylinder. The rubber air tube is installed at the bottom of the sealing groove. The height of the slots on both sides of the sealing groove is different. The middle of the inner walls on both sides of the left sealing groove and the upper part of the inner walls on both sides of the right sealing groove are machined with protrusions, and the sealing strip is machined with grooves in corresponding parts.

Figure 2a shows the structure of the sealing strip at the beginning of use. The groove on the side of the sealing strip is still a distance away from the lower part of the convex platform on the side wall of the sealing groove. Under the action of the rubber air tube, the sealing strip is gradually worn and moved up on the inner wall of the cylinder until, as shown in Figure 2b, the lower part of the groove on the side of the sealing strip is close to the lower part of the convex platform on the side wall of the sealing groove. Due to the obstruction of the convex platform on the side wall of the sealing groove, the sealing strip cannot continue to move. The sealing strip and the inner wall of the cylinder reach a critical contact state, and the sealing strip will no longer continue to wear. At this time, due to the critical contact state between the sealing strip and the inner wall of the cylinder, while ensuring the sealing performance, the friction between the sealing strip and the inner wall The power consumption caused by friction between the inner walls of the cylinder is also significantly reduced.