Related Application

[0001] The present application claims priority from and the benefit of U.S. Provisional Patent Appl ication No. 62/327,847, filed April 26, 20I6, the disclosure of which is hereby incorporated herein in its entirety.

Field of the Invention

[0002] The present invention relates generally to industrial rolls, and more particularly to roils for papermaking.

Background of the invention

[0003] Cylindrical rolls are utilized in a number of industrial applications, especially those relating to papermaking. Such rolls are typically employed in demanding environments in which they can be exposed to high dynamic loads and temperatures and aggressive or corrosive chemical agents. As an example, in a typical paper mill, rolls are used not only for transporting a fibrous web sheet between processing stations, but also, in the case of press section and calender rolls, for processing the web sheet, itself into paper.

[0004] A papermaking machine may include one or more suction rolls placed at various positions within the machine to draw moisture from, a belt (such as a press felt) and/or the fiber web. Each suction roll is typically constructed from a metallic shell covered by a polymeric- cover with a plurality of hoies extending radially therethrough. Vacuum pressure is applied with a suction box located in the interior of the suction roll shell. Water is drawn into the radially- extending holes and is either propelled eentrifuga!ly from the holes after they pass out of the suction zone or transported from the interior of the suction roil shell through appropriate fluid conduits or piping. The holes are typically formed in a grid-like pattern by a multi-bit drill thai forms a line of multiple -holes at once (for example, the drill may form fifty aligned holes at once). In many grid patterns, the holes are arranged such that rows and columns of holes are at an oblique, angle to the longitudinal axis of the roll. Additional information regarding suction rolls is provided in U,S Patent. Publication No. 2016/0076200, published March 17, 2016, the disclosure of which is hereby incorporated herein in its entirety.

[0005] Also, in some suction rolls, blind drilled boles are included in the roll cover to assist with drainage. It may be desirable to provide a pattern of suction holes and blind drilled holes that improves performance of the roll cover.

[0006] As a first aspect, embodiments of the invention are directed to an industrial roll, comprising: a substantially cylindrical shell having an outer surface and an internal lumen; and a polymeric cover circumferential iy overlying the shell outer surface, wherein the shel l and cover have a plurality of through holes that provide fluid communication between the lumen and the atmosphere, and the cover has a plurality of blind drilled holes. The through holes and the blind drilled holes are arranged in a pattern in which:

(a) the through holes are arranged in rows that define an oblique angle relative to a plane that is perpendicular to a longitudinal axis of the roll;

(b) the through holes of one row are offset from the through holes of the adjacent row, with the offset between rows defining an angle of approximately 20-40 degrees;

(c) the blind drilled holes are arranged in rows located between the rows of through holes;

(d) the blind drilled holes of one row are offset slightly from the blind drilled holes of the adjacent row, with the offset between rows defining an angle similar to that defined by the through holes: and

(e) each of the blind drilled holes is located at the substantial center of a triangle defined by the closest three through holes.

[0007] As a second aspect, embodiments of the invention are directed to a cylindrical polymeric cover for an industrial roll, the cover including a plurality of through holes and a plurality of blind drilled holes. The through holes and the blind drilled holes are arranged in a pattern in which:

(a) the through holes are arranged in rows that define an oblique angle relative to a plane that is perpendicular to a longitudinal axis of the cover: (b) the through holes of one row are offset from the through holes of the adjacent row, with the offset between rows defining an angle of approximately 20-40 degrees;

(c) the blind drilled hoies are arranged in rows located between the rows of through holes;

(d) the blind drilled holes of one row are offset slightly from the blind drilled holes of the adjacent row, with the offset between rows defining an angle similar to that defined by the through holes; and

(e) each of the blind drilled holes is located at the substantial center of a triangle defined by the closest three through holes.

[0008] As a. third aspect, embodiments of the invention are directed to an industrial roll, comprising: a substantially cylindrical shell having an outer surface and an Internal lumen; and a polymeric cover circumferentially overlying the shell outer sur face. The shell and cover have a plurality of through holes that provide fluid communication between the lumen and the atmosphere, and the cover has a plurality of blind drilled holes. The through holes and the blind drilled hoies are arranged in a pattern in which:

(a) the through holes are arranged in rows that define an oblique angle relative to a plane that is perpendicular to a longitudinal axis of the roll;

(b) the through hoies of one row are offset from the through holes of the adjacent row;

(c) the blind drilled holes are arranged in rows located between the rows of through holes;

(d) the blind drilled hoies of one row are offset slightly from the blind drilled holes of the adjacent row, with the offset between rows defining an angle similar to that defined by the through holes; and

(e) each of the blind drilled holes is located at the substantial center of a triangle defined by the closest three through holes.

Brief Description of the Figures

[0009] Figure 1 is a gage view of a suetion roll with a cover according to embodiments of the present invention. [0010] Figure 2 is a gage perspective view of the roll and roll cover of Figure t being drilled with a drill.

[0011] Figure 3 is a greatly enlarged view of the suction hole and blind drilled hole pattern of the roll cover of Figure 1.

Detailed Description

[0012] The present invention will be described more particularly hereinafter with reference to the accompanying drawings, The invention is not intended to be limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the invention to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.

[0013] Unless otherwise defined, all technical and scientific terras used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention be longs. The terminology used in t he description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Where used, the terms "attached", "connected", "interconnected", "contacting", "coupled", "mounted" and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise.

[0014] Referring now to the figures, a suction roll, designated broadly at 20, is illustrated in Figure I. The suction roil 20 includes a hollow cylindrical shell or core 22 and a cover 24 (typically formed of one or more polymeric materials) that encircles the shell 22. The shell 22 (seen in Figure 2} is typically formed of a corrosion -resistant metallic material, such as stainless steel or bronze. A suction box (not shown) is typically positioned within the lumen of the shell 22 to apply negative pressure (he,, suction) through holes in the shell 22 and cover 24.

Typically, the shell 22 will already include through holes that will later align with through holes 82 in the cover 24, An exemplary shell and suction box combination is illustrated and described in U.S. Patent No. 6,358,370 to Huttunen. the disclosure of which is hereby incorporated herein in its entirety. [0015] The cover .24 can take any form and can be formed of any polymeric and/or eiastomeric materia! recognized by those skilled in this art to be suitable for use with a suction roll. Exemplary materials include natural rubber, synthetic rubbers such as neoprene, styrene- butadiene (SBR), mtrile rubber,, chiorosuifonated polyethylene ("CSPE" - also known under the trade name HYPALON), EDPM (the name; given to an ethylene-propylene terpolymer formed of ethylene-propylene diene monomer), epoxy, and poiyurethane. In many instances, the cover 24 will comprise multiple layers. Figure 2 illustrates that an inner base layer 42a, an outer base layer 42b and a topstock layer 70 are applied; additional layers, such as a "tie-in" layer between the base and topstock layers 42% 42b, 70 and an adhesive layer between the shell 22 and the inner base layer 42, may also be included. The cover 24 may also include reinforcing and filler materials, additives, and the like, Exemplary additional materials are discussed in U.S. Patent Nos. 6,328,681 to Stephens, 6,375,602 to Jones and 6,981 ,935 to Gustafson, the disclosures of each of which are hereby incorporated herein in their entireties,

[0016] The cover 24 has a pattern of holes includes through holes 82 and blind drilled holes 84. As can be seen in Figure 3, the pattern of holes is one in which:

(a.) the through holes 82 are arranged in rows that define an oblique angle 0 (typically between about 5 and 20 degrees) relative to a plane that is perpendicular to the longitudinal axis of the roll 20.;

(b) the through holes 82a of one row are offset from the through holes 82b of the adjacent row, with the offset between rows defining an angle a of approximately 20-40 degrees;

(c) the blind drilled holes 84 are arranged in rows located between the rows of through holes 82;

(d) the blind drilled holes 84a of one row are offset slightly from the blind drilled holes of the adjacent row, with the offset between rows defining an angle similar to that defined by the through holes 82; and

(e) each of the blind drilled holes 84 is located at the center of a triangle T defined by the closest three through holes 82 (e.g., the blind drilled hole 84' is located at the center of the triangle defined by through holes 82', 82" of row of through holes 82 b and through hole 82"' of row of through holes 82a), This positioning causes the spacing of each row of blind drilled holes 84 from its adjacent rows of through holes 82 to differ. In one embodiment, a row of blind drilled holes 84 (e.g., row 84a) is between about 1.8 to 2,2 times farther from one adjacent row of through holes 82 (e.g., row 82a) as from its other adjacent row of through holes §2 (e.g., row 82b) with the positions of the rows measured from lines through the hole centers,

[0017] In this pattern, advantages over prior patterns can be realized. The sizes of both the through holes.82 and the blind drilled holes 84 can be increased compared to prior designs. The land distance between holes 82, 84 is typically a limiting factor in hole pattern design, with a minimum land distance required for a given roll and roll cover. With this pattern, the minimum land distance between a blind drilled hole 84 and the three surrounding through holes 82 can be met comfortably, and can enable larger through holes 82 and/or blind drilled holes 84 to be used, in turn, the use of larger holes 82, 84 can increase the open area of the roll cover 24, which can improve performance. Additionally, the use of larger holes 82, 84 can render the cover 24 less likely to suffer from plugging of the holes 82, 84, which can be a performance issue with suction roils.

[0018] The cover for the suction roll 20 can be processed in any number of ways . After th e top stock layer 70 is cured, the through holes 82 and the blind drilled holes 84 are formed in the cover 24 and. in the event that through holes 82 have not already been formed in the shell 22, are also formed therein. The through holes 82 and blind drilled holes 84 can be formed by any technique known to those skilled in this art, but are preferably formed with a multi-bit drill 80 as- shown in Figure 2 (an exemplary drill is the DRILLMATICC machine, available from Safop, Pordenone, Italy).

[0019] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.