Suction roller with pattern of through holes and blind holes to improve soil removal

Description

Related Application

[0001] The present application claims priority from and the benefit of U.S. Provisional Patent Application No. 62 / 327,847, filed April 26, 2016.Field of the Invention

[0002] The present invention relates generally to industrial rolls, and more particularly to rolls 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 holes 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 centrifugally from the holes after they pass out of the suction zone or transported from the interior of the suction roll shell through appropriate fluid conduits or piping. The holes are typically formed in a grid-like pattern by a multi-bit drill that 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. CN 203 960 658 discloses a taper-hole single chamber suction press roll.

[0005] Also, in some suction rolls, blind drilled holes 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.Summary

[0006] As a first aspect, embodiments of the invention are directed to a cylindrical polymeric cover for an industrial roll as defined in appended independent claim 1.

[0007] As a second aspect, embodiments of the invention are directed to an industrial roll as defined in appended claim 5.

[0008] Further embodiments are given in the appended dependent claims.Brief Description of the Figures

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

[0010] 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.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the 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.

[0012] Referring now to the figures, a suction roll, designated broadly at 20, is illustrated in Figure 1. The suction roll 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 (i.e., 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.

[0013] The cover 24 can take any form and can be formed of any polymeric and / or elastomeric material 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, styrenebutadiene (SBR), nitrile rubber, chlorosulfonated 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 polyurethane. 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 42a, 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.

[0014] 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 θ (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 α 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 82b 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 82 (e.g., row 82b ) with the positions of the rows measured from lines through the hole centers.

[0015] 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 rolls.

[0016] The cover for the suction roll 20 can be processed in any number of ways. After the 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 DRILLMATIC machine, available from Safop, Pordenone, Italy).

[0017] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. The invention is defined by the following claims.

Claims

1. A cylindrical polymeric cover (24) for an industrial roll (20), the cover (24) including a plurality of through holes (82) and a plurality of blind drilled holes (84), wherein the through holes (82) and the blind drilled holes (84) are arranged in a pattern in which: (a) the through holes (82) are arranged in rows that define an oblique angle (θ) relative to a plane that is perpendicular to a longitudinal axis of the cover (24); (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 (α) 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 (84) of one row are offset slightly from the blind drilled holes (84) of the adjacent row, with the offset between rows defining an angle similar to that defined by the through holes (82); characterized in that (e) each of the blind drilled holes (84) is located at the substantial center of a triangle (T) defined by the closest three through holes (82).

2. The polymeric cover (24) defined in Claim 1, wherein each of the blind drilled holes (84) is nearer to a first adjacent row of through holes (82) than to a second adjacent row or through holes (82).

3. The polymeric cover (24) defined in Claim 1, wherein each of the blind drilled holes (84) is between 1.8 and 2.2 times nearer to the first adjacent row of through holes (82) than to the second adjacent row of through holes (82).

4. The polymeric cover (24) defined in Claim 1, wherein the oblique angle (θ) defined by the through holes (82) is between about 5 and 20 degrees.

5. An industrial roll (20), comprising: a substantially cylindrical shell (22) having an outer surface, an internal lumen, and a plurality of through holes; and a polymeric cover (24) as defined in Claim 1 circumferentially overlying the shell outer surface, wherein the through holes (82) of the cover (24) align with the through holes of the shell (22) to provide fluid communication between the lumen and the atmosphere.

6. The industrial roll (20) defined in Claim 5, wherein each of the blind drilled holes (84) is nearer to a first adjacent row of through holes (82) than to a second adjacent row of through holes (82).

7. The industrial roll (20) defined in Claim 6, wherein each of the blind drilled holes (84) is between 1.8 and 2.2 times nearer to the first adjacent row of through holes (82) than to the second adjacent row of through holes (82).

8. The industrial roll (20) defined in Claim 5, wherein the industrial roll (20) is a suction roll of a papermaking machine.

9. The industrial roll (20) defined in Claim 5, wherein the oblique angle (θ) defined by the through holes (82) is between about 5 and 20 degrees.