Vacuum equipment for a fiber web machine and a fiber web machine provided with vacuum equipment

A suction box in a fiber web machine, wherein a fabric is arranged movable over the suction box to define a machine direction, comprising:

• a frame mounted to the fiber web machine, the frame having an interior connected to a source of vacuum;
• a cover mounted to the frame, the cover separating the fabric from the frame interior forming the source of vacuum, the cover having a wear surface and having portions defining a plurality of openings, said openings being defined by opposite edges, the opposite edges defining a distance x in the machine direction therebetween, the openings in the cover for extending a vacuum effect from the interior;
• a fabric included in the fiber web machine and set in contact with the cover wear surface so that the vacuum effect is applied to the fabric;
• and
• wherein the cover is formed from sheet metal having a thickness s between the fabric and the frame interior forming the source of vacuum which is less than or equal to the distance x.

A suction box in a fiber web machine comprising:

• a frame arranged to be supported on the fiber web machine, the frame having an interior forming a source of vacuum;
• a fabric mounted for motion in a machine direction on the fiber web machine so the fabric is movable along a fabric path, the fabric path defining a machine direction;
• a cover, the cover separating the fabric from the frame interior forming the source of vacuum, wherein the cover is formed of sheet metal 2-10 mm thick mounted to the frame, the cover having a wear surface and having portions defining a plurality of openings, said openings being defined by opposite edges, the opposite edges defining a distance in the machine direction of 10-25 mm therebetween, the openings in the cover for extending a vacuum effect from the interior;
• wherein the cover extends with respect to the fabric in a cross direction perpendicular to the machine direction, and the fabric path over the cover is defined with respect to movement of the fabric over the cover in the machine direction;
• wherein the cover includes a first bend at a leading edge which is upstream in the machine direction so the fabric first engages the leading edge and a second bend at a trailing edge which is downstream in the machine direction so the fabric last engages the trailing edge, the first bend and the second bend in the sheet metal to form an upside down U-shape which extends with respect to the fabric in the cross direction;
• and
• wherein the fabric is in contact with the cover wear surface which forms the top of the upside down U-shape.