US 5,147,508 AGranted

Suction box covers for cleaning papermaking machine felts

AssigneeThe Nash Engineering Company

InventorDouglas F. Sweet

Life of this patent

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Abstract

A suction box for use in drying a felt web in a papermaking machine has one or more cover members in contact with a surface of the felt web. The surface of at least one of these cover elements which normally contacts the felt web has a leading portion which is feathered or inclined away from the surface of the felt web in the direction opposite the direction of motion of the felt web. This allows the felt web to come into contact with the cover member surface more gradually, which reduces wear on the felt.

Claims19

Dependent claims

In a papermaking machine having a forming section for forming and partly drying a paper web, and a separate press section to which the formed and partly dried paper web is transferred for further drying, press section apparatus comprising:

a moving felt web for receiving the paper web from the forming section;
and
a suction box for applying suction to said moving felt web, said felt web being substantially planar adjacent to said suction box and moving relative to said suction box from a location upstream from said suction box to a location downstream from said suction box, said suction box including:
a longitudinal chamber extending longitudinally substantially parallel to the plane of said felt web and transverse to the direction of motion of said felt web, said chamber having an open side adjacent said felt web for communicating reduced pressure in said chamber to said felt web, said open side having substantially parallel first and second edges which are respectively upstream and downstream of said open side in relation to the direction of motion of said felt web;
a first wear strip mounted on said first edge;
and
a second wear strip mounted on said second edge, said first and second wear strips being spaced from one another parallel to the direction of motion of said felt web, each of said wear strips having a surface which includes a substantially planar portion substantially parallel to the plane of said felt web, said planar portions of said first and second wear strips being in contact with respective first and second portions of a surface of said felt web, and said surface of at least one of said wear strips including a feathered portion which is upstream from the remainder of said surface in relation to the direction of motion of said felt web, said feathered portion being inclined away from the plane of said felt web in the direction opposite the direction of motion of said felt web so that said felt web comes into contact with said surface of said at least one of said wear strips more gradually than it would in the absence of said feathered portion, said feathered portion being substantially planar and at least about 25% of the dimension of said surface of said at least one of said wear strips parallel to the direction of motion of said felt web, and wherein said paper web is in contact only with a third portion of a surface of said felt web, said third portion being upstream from said first portion in relation to the direction of motion of said felt web.

4 more elements

In a papermaking machine having a forming section for forming and partly drying a paper web and a separate press section to which the formed and partly dried web is transferred for further drying, press section apparatus comprising:

a moving felt web for receiving the paper web from the forming section;
and
a suction box for applying suction to said moving felt web, said felt web being substantially planar adjacent to said suction box and moving relative to said suction box from a location upstream from said suction box to a location downstream from said suction box, said suction box including:
a longitudinal chamber extending substantially parallel to the plane of said felt web and transverse to the direction of motion of said felt web, said chamber having an open side adjacent said felt web, said open side having substantially parallel first and second edges which are respectively upstream and downstream of said open side in relation to the direction of motion of said felt web;
and
a cover member mounted on said chamber between said first and second edges, said cover member having a surface which includes a substantially planar portion substantially parallel to the plane of said felt web, said planar portion of said cover member being in contact with a first portion of a surface of said felt web, said surface of said cover member having a feathered portion which is upstream from the remainder of said surface in relation to the direction of motion of said felt web, said feathered portion being inclined away from the plane of said felt web in the direction opposite the direction of motion of said felt web so that said felt web comes into contact with said surface of said cover member more gradually than it would in the absence of said feathered portion, said feathered portion being substantially planar and at least about 25% of the dimension of said surface of said cover member parallel to the direction of motion of said felt web, and said remainder of said surface of said cover member being perforated to communicate reduced pressure in said chamber to said felt web, and wherein said paper web is in contact only with a second portion of said felt web, said second portion being upstream from said first portion in relation to the direction of motion of said felt web.

3 more elements

Dependencies are inferred from the claim text.

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Abstract

a moving felt web for receiving the paper web from the forming section;
and
a suction box for applying suction to said moving felt web, said felt web being substantially planar adjacent to said suction box and moving relative to said suction box from a location upstream from said suction box to a location downstream from said suction box, said suction box including:
a longitudinal chamber extending longitudinally substantially parallel to the plane of said felt web and transverse to the direction of motion of said felt web, said chamber having an open side adjacent said felt web for communicating reduced pressure in said chamber to said felt web, said open side having substantially parallel first and second edges which are respectively upstream and downstream of said open side in relation to the direction of motion of said felt web;
a first wear strip mounted on said first edge;
and
a second wear strip mounted on said second edge, said first and second wear strips being spaced from one another parallel to the direction of motion of said felt web, each of said wear strips having a surface which includes a substantially planar portion substantially parallel to the plane of said felt web, said planar portions of said first and second wear strips being in contact with respective first and second portions of a surface of said felt web, and said surface of at least one of said wear strips including a feathered portion which is upstream from the remainder of said surface in relation to the direction of motion of said felt web, said feathered portion being inclined away from the plane of said felt web in the direction opposite the direction of motion of said felt web so that said felt web comes into contact with said surface of said at least one of said wear strips more gradually than it would in the absence of said feathered portion, said feathered portion being substantially planar and at least about 25% of the dimension of said surface of said at least one of said wear strips parallel to the direction of motion of said felt web, and wherein said paper web is in contact only with a third portion of a surface of said felt web, said third portion being upstream from said first portion in relation to the direction of motion of said felt web.

4 more elements