Patent ID: 6952888

Claim:
A dryer vacuum box in a dryer part of a paper machine for applying vacuum suction force from a vacuum source through a canvas to a paper web, the paper web traveling with the canvas on the circumferential surface of a dryer roll, said dryer vacuum box comprising: a first vacuum box having an opening facing an area including a peeling point, the peeling point being the point at which the canvas together with the paper web leaves the circumferential surface of the dryer roll, wherein said opening is covered with the surface of the canvas in the area including the peeling point so that an enclosed space is defined by said first vacuum box and the canvas, said first vacuum box being connected to a vacuum source so that the degree of vacuum in said first vacuum box is adjustable, whereby a vacuum suction force can be applied to the canvas in the area surrounding the peeling point; and a second vacuum box having an opening facing a draw area of the canvas, the draw area lying between the dryer roll and another roll downstream of the dryer roll with respect to the paper web path, wherein said opening is covered with the draw area of the canvas so that another enclosed space is defined within said second vacuum box and a vacuum suction force is applied inside of said second vacuum box; wherein said first vacuum box is inside of said second vacuum box and the degree of vacuum in said first vacuum box is set higher than in said second vacuum box.