US3821076A

US3821076A - Forming roll for twin wire papermaking with axially aligned wave-shaped ribs

Info

Publication number: US3821076A
Application number: US00322690A
Authority: US
Inventors: E Stenberg; E Emanuelsson
Original assignee: KARLSTAD MEKANISKA AB
Current assignee: KARLSTAD MEKANISKA AB; KARLSTADS MEKANISKA WERKSTAD SW AB; Valmet Paper Machinery Inc
Priority date: 1973-01-11
Filing date: 1973-01-11
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28

Abstract

A forming roll for a paper-making machine of the two wire type comprises a cylindrical roll body and a multiplicity of generally corrugated-shaped ribs extending generally radially outwardly from and generally longitudinally along the surface of the cylindrical body. All of the ribs are of substantially identical wave shape along their lengths, and the ribs are substantially equally spaced apart circumferentially of the body. The ribs define a multiplicity of zig-zag, regular wave-like cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll. The medial axes of all of the cells at corresponding points circumferentially of the roll intersect cross-sectional planes of the roll at substantially the same angle such that the wave forms of all cells are substantially in phase longitudinally of the roll.

Description

i 3,821,076 June 28,1974

1 1 FORMING ROLL FOR TWIN WIRE PAPERMAKING WITH AXIALLY ALIGNED WAVE-SHAPED RIBS [75] Inventors: Erik Gunnar Stenberg, Karlstad;

Ernst Ingemar Emanuelsson, Skoghall, both of Sweden [73] Assignee: Aktiebolaget Karlstads Mekaniska Werkstad, Karlstad,v Sweden 221 Filed: Jan. 11,1973

21 Appl. No.2 322,690

[56] References Cited UNITED STATES PATENTS Trotman Gustafson et a1.

Primary Examiner--S. LeonBashore Assistant Examiner-Richard H. Tushin Attorney, Agent, or Firm-Brumbaugh, Graves, Donohue & Raymond [57] ABSTRACT A forming roll for a paper-making machine of the two wire type comprises a cylindrical roll body and a multiplicity of generally corrugated-shaped ribs extending generally radially outwardly from and generally longitudinally along the surface of the cylindrical body. All of the ribs are of substantially identical wave shape along their lengths, and the ribs are substantially equally spaced apart 'circumferentially of the body. The ribs define a multiplicity of zig-zag, regular wavelike cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll. The rnedial axes of all of the cells .at corresponding points circumferentially of the roll intersect cross-sectional planes of the roll at substantially the same angle such that the wave forms of all roll.

3 Claims, 3 Drawing Figures cells are substantially in phase longitudinally of the PAIENIEDJUNZBISH FIG.1

SHEET 1 OF 2 HBELOTB PATENTEDJUH 2 8 19741 SHEET 2 [IF 2 FIG.2

FORMING ROLL FOR TWIN WIRE PAPERMAKING WITH AXIALLY ALIGNED WAVE-SHAPED RIBS BACKGROUND OF THE INVENTION One type of paper-making machine, which is generally known as a two wire type machine, comprises two foraminous belts, usually called wires, that are movable along endless paths that include convergent runs in which the two wires converge in the direction of their movement toward the surface of a roll (a forming roll) and then run conjointly around a portion of the roll surface with the inner belt in engagement with the roll surface and with a layer of stock captured in sandwich relation between the two wires. Stock is introduced in the form of a ribbon-like jet into the space between the wires at the zone where the two wires converge toward the roll. The stock intrudes between the wire and drains outwardly through the outer wire and inwardly through the inner wire along the conjoint run where the two wires run together over the surface of the roll.

Effective stock drainage through the inner wire requires that the forming roll over which the wires run have as great an open area as possible, thereby to be highly receptive to water drained through the inner wire. Various types of rolls formed with various forms of surface structure have been proposed. With many forms of the roll surface, there is noticeable marking of the paper made on the machine. In some cases, the roll surface has been found to cause relatively rapid wear of the inner wire, thus increasing wire costs as well as reducing output because of down-time for wire replacement.

SUMMARY OF THE INVENTION There is provided, in accordance with the present invention, a forming roll for a two wire type papermaking machine that presents a large amount of open area to the wire, thereby to enhance stock drainage inwardly through the inner wire. The large open area is a result of providing minimum surface area of contact between the wire and the roll. Nonetheless, notwithstanding the small contact surface between the wire and roll surface, it has been found that wire wear is kept to a minimum. Moreover, paper made on a machine having a forming roll according to the invention does not show marking by the roll.

More particularly, a forming roll of a two wire type paper-making machine comprises a cylindrical roll body and a multiplicity of generally corrugated-shaped ribs extending radially outwardly from and generally longitudinally along the surface of the roll body. All of the ribs are of substantially identical wave shape along their lengths, and the ribs are substantially equally spaced apart circumferentially of the body to define a multiplicity of zig-zag, regular wave-like cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll. Corresponding points along the medial axes of all of the cells intersect common cross-sectional planes of the roll at substantially the same angle so that the wave forms of all cells are substantially in phase with each other longitudinally of the roll.

In a preferred form of cell structure, the pitch distance measured circumferentially of the roll between DESCRIPTION OF THE DRAWINGS FIG. 1 is a generally schematic side view of the forming part of a paper-making machine employing an embodiment of the improved forming roll;

FIG. 2 is a plan view of a segment of the surface of the roll of FIG. 1', and

FIG. 3 is a view in cross-section of a small segment of the roll of FIGS. 1 and 2 taken generally along the lines 33 of FIG. 2 and in the direction of the arrows.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT An exemplary embodiment of a paper-making machine of the two wire type employing the improved roll, according to the present invention, comprises an inner wire 2 and an outer wire 3 that converge toward a forming roll 1 and then run conjointly over a segment of the surface of the roll. A stock delivery nozzle 4 conducts a ribbon-like jet 5 of paper-making stock into the convergent run where the wires 2 and 3 converge toward the roll. The velocity of the jet is greater than the speeds of the wires, and thus the jet is decelerated upon impinging on the wires. In addition, the velocity of the jet develops a drainage pressure in the stock, the drainage pressure balancing a predetermined tension maintained in the outer wire and being proportional to the wire tension and inversely proportional to the roll radius. Drainage of the stock commences upon the impingement of the jet with the respective wires and con tinues throughout the conjoint run of the two wires over the forming roll. A portion of the drainage, usually approximately one half of the total drainage, is outwardly through the outer wire 3 while the remaining drainage occuring in the forming zone occurs inwardly through the inner wire. Liquids draining through the outer wire are collected in a collector for removal through a bottom outlet; liquids draining inwardly through the inner wire 2 are collected and retained in the surface structure of the forming roll 1.

More particularly, as described in greater detail below, the surface of the roll 1 has a multiplicity of circumferentially separate cells 7 where liquids drained through the inner wire are collected and held. A suction box 8 within the roll is maintained under vacuum conditions that substantially balance the centrifugal forces acting on the liquids collected in the cells and tending to force the liquids back out through the inner wire and back into the newly formed fibrous web. The vacuum in the'suction box 8 (or vacuums of different magnitudes in different sections of a suction box) is communicated to the cells 7 through passageways or openings 10 in an inner body portion 11 of the roll. It is not intended that any liquids be removed from the cells and drawn into the suction box through the openings l0, and this condition is maintained by providing appropriate vacuum conditions in the suction box 8 that are just sufficient to balance centrifugal force acting on liquids received in the cells. The bodies of liquid accumulating in the cells 7 throughout the conjoint run of the two wires are ultimately ejected or thrown off in a generally tangential direction, as indicated by the arrowed line designated by the reference numeral 12, and are collected in a collector 13 for removal through an outlet opening in the bottom.

As may best be seen in FIGS. 2 and 3 of the drawings, a forming roll, according to the present invention, comprises an inner body 11 in the form ofa cylindrical shell having the strength and rigidity appropriate for the size of the machine. The cells 7 that receive the drained liquid are defined by a multiplicity of generally corrugated-shaped strips or ribs 14 which are, preferably, welded onto the surface of the body 11. The outer edges of the ribs 14 form the roll surface and support the wires. In a preferred embodiment, the ribs 14 extend continuously longitudinally across the cylindrical body over that portion of the inner wire through which stock drainage occurs. As illustrated in FIG. 2, each end of the roll may have a flange or shoulder 17 that defines a face 15 at the end of the drainage portion of the roll, the ribs 14 abutting and being joined to the face 15. The major surface of the roll body 11 is a circular cylinder of a diameter less than that of the shoulders and the surface defined by the edges of the ribs and is designated by the reference numeral 16, the surface of the body thus defining the inner or base wall of each cell 7 that is further defined by the respective ribs 14.

As may best be seen in FIG. 2, considered in conjunction with FIG. 1, all of the ribs 14 are of substantially identical wave shape along their lengths, and the ribs are substantially equally spaced apart circumferentially of the body. Thus, the ribs 14 define a multiplicity of zig-zag, regular wave-like cells 7 that are of uniform size and shape. Each of the cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll. Indeed, it is preferred that the cells extend continuously from end to end of the roll between the flanges 17 at opposite ends of the rolls.

At corresponding points circumferentially of the roll the medial axes of all cells intersect radial crosssectional planes of the roll at substantially the same angles so that the wave forms of all rolls are substantially in phase longitudinally of the roll. In other words, the ribs and the cells that they define are geometrically and dimensionally oriented to form a regular wave pattern with corresponding points in each such wave pattern located in a common plane perpendicular to the axis of the roll. It will also be observed in FIG. 2 that the passages 10 are located to communicate with each cell, the holes being located in zig-zag rows that correspond in shape substantially to the wave form of the cells.

Preferably, the pitch distance between the medial axes of the cells measured circumferentially of the roll is substantially equal to the amplitude of the wave forms of the cells between adjacent loops. This places the corresponding trailing loops of a rib defining a leading (relative to roll rotation) end of a given cell generally in longitudinal alignment with the leading loops of the rib defining the trailing end of such cell.

The above-described embodiment is intended to be merely exemplary, and many variations and modifications of the embodiment may be made by those skilled in the art without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

We claim:

1. In a paper-making machine of the type having a r0- tatable roll, an inner foraminous belt and an outer foraminous belt movable along endless paths that include a convergent run in which they converge in the direction of their movement toward the roll surface and a conjoint run in which they run conjointly around a portion of the roll surface with the inner belt in engagement with the roll surface, and a stock delivery nozzle for introducing a ribbon-like jet of paper-making stock under pressure between the belts at the convergent run thereof, whereby a layer of stock is received between the belts and moves with them along their conjoint run for drainage outwardly through the outer belt and inwardly through the inner belt along such conjoint run, an improvement wherein the rotatable roll comprises a cylindrical body and a multiplicity of generally corrugated-shaped ribs extending radially outwardly from and generally longitudinally along the surface of the cylindrical body, all ribs being of substantially identical wave shape along their lengths and the ribs being substantially equally spaced-apart circumferentially of the body to define a multiplicity of zig-zag regular wavelike cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is sub; stantially greater than its dimension circumferentially of the roll, and all of which cells have medial axes that at corresponding points circumferentially of the roll intersect radial cross-sectional planes of the roll at substantially the same angle such that the wave forms of all cells are substantially in phase longitudinally of the roll.

ward stock drainage through the belt occurs.

Claims

1. In a paper-making machine of the type having a rotatable roll, an inNer foraminous belt and an outer foraminous belt movable along endless paths that include a convergent run in which they converge in the direction of their movement toward the roll surface and a conjoint run in which they run conjointly around a portion of the roll surface with the inner belt in engagement with the roll surface, and a stock delivery nozzle for introducing a ribbon-like jet of paper-making stock under pressure between the belts at the convergent run thereof, whereby a layer of stock is received between the belts and moves with them along their conjoint run for drainage outwardly through the outer belt and inwardly through the inner belt along such conjoint run, an improvement wherein the rotatable roll comprises a cylindrical body and a multiplicity of generally corrugatedshaped ribs extending radially outwardly from and generally longitudinally along the surface of the cylindrical body, all ribs being of substantially identical wave shape along their lengths and the ribs being substantially equally spaced-apart circumferentially of the body to define a multiplicity of zig-zag regular wave-like cells of uniform size and shape, each of which cells has a dimension longitudinally of the roll that is substantially greater than its dimension circumferentially of the roll, and all of which cells have medial axes that at corresponding points circumferentially of the roll intersect radial cross-sectional planes of the roll at substantially the same angle such that the wave forms of all cells are substantially in phase longitudinally of the roll.

2. The improvement according to claim 1 wherein the pitch distance between the medial axes of the cells measured circumferentially of the roll is substantially equal to the amplitude of the wave forms of the cells between adjacent loops thereof.

3. The improvement according to claim 1 wherein the ribs and the cells defined thereby extend substantially the entire length of the part of the roll where inward stock drainage through the belt occurs.