Suction couch roll

          Couch roll (also known as “cooch”) is used in paper machine to remove water by application of vacuum. It acts as the last “wrap” where the wet web leaves the forming wire (wire part) and enter into the wet-press section (press part). On the surface of the couch roll we found rows of small holes to suck the water. Inside the roll baffles (long and end strips) are present. These baffles direct the vacuum towards the portion of the roll where the wet web of paper is on the fabric. Below of the long baffle strips air tubes are present for strip movement. Below the end baffle strips springs are present to seal the roll for vacuum suction creation. In the vacuum box one shower will present, it cools the rubber material on the roll. In vacuum boxes if we increase the vacuum we need more power to drive the forming fabric. But in couch roll if we applied too high vacuum it produces visible suction-hole “shadows” due to the movement of fines within the sheet.