US3440138A - High speed web forming machine - Google Patents

Description

April 22, 1969 R. E. SMITH HIGH SPEED WEB FORMING MACHINE Sheet Filed Oct. 19, 1965 I NVENTOR.

ROBERT E. SMITH TZZOFQQ A T TOR/VE Y.

April 22, 1969 R. E. SMITH HIGH SPEED WEB FORMING MACHINE Filed Oct. 19, 1965 INVENTOR.

ROBERT E. SMITH TNQ TNW

ATTORNEY.

United States: Patent O U.S. Cl. 162-351 3 Claims ABSTRACT F THE DISCLOSURE A papermaking machine wherein a stock slurry is delivered to an endless wire at a forming zone, which may be open to atmosphere under vacuum, with the wire and its supported web passing from the forming zone in seriatim over a plurality of low vacuum zones, the wire being supported in part by a plurality of grooved iin type capillary rolls which themselves deline sections of partitions between adjacent vacuum compartments, the other sections of partitions being formed by wall portions of the compartments, with the'confronting rolls and wall portions being sealed by means of labyrinth seals wherefore a low friction resistance is experienced over each of the vacuum areas so as to result in low driving horsepower requirements.

This invention -relates to papermaking and like machines, and more particularly to a simplified construction of a high speed web forming machine for for-ming webs from slurries of iibrons materials under improved degrees of drainage control and at accelerated rates of speed.

The invention is aimed primarily at avoiding employment of the costly rotatable drum of the conventional cylinder mould and thereby the attendant heavy expenditure of power in driving same. By dispensing therewith, the construction of the machine is simplified, particularly as respects the drum per se and the connections of suction supply to its interior.

As a principal feature hereof, I provide improvements in the wet end of a papermaking machine used in extracting water from pulp conveyed onto and via an endless wire wherein the said wire is a relatively short one and yet is capable of forming sheets under varying degrees of vacuum and further wherein I provide a controlled drainage rate and hence a controlled web formation through a plurality of spaced separately-controlled low-vacuum boxes with the endless wire being conveyed relative thereto with a minimum amount of friction, the commonly-used type of suction box being a chief cause of wear and strain.

Stated in another way, the invention comprehends means, for delivering stock to a continuously moving endless wire, cooperant with means for guiding the Wire over an extended substantially oval or circular path, and means for applying suction to at least a part or parts of the interior of that endless path, therewith to remove the liquid from the stock deposited upon the wire.

The invention may be embodied in any device wherein a stock slurry is delivered to an endless wire at a forming zone, which may be open to atmosphere under vacuum, with the wire and its supported web passing from the forming zone in seriatim over a plurality of low vacuum zones, the wires being supported in part by a plurality 0E grooved n type capillary rolls which themselves define sections of partitions between adjacent vacuum compartments, the other sections of partitions being formed by wall portions of the compartments, with the confronting rolls and wall portions being sealed by means of labyrinth seals wherefore a low friction resistance is experienced 3,440,138 Patented Apr. 22, 1969 ice over each of the vacuum areas so as to result in low driving horsepower requirements.

Another feature hereof lies in the allowance of the exploitation of low vacuum sources, such as fans or the like, made possible by reason that the objectionable centrifugal forces, inherent with forming devices employing drilled shells such as in cylinder moulds or suction breast rolls are not here present, thereby to permit higher machine speeds with lower driving horsepower requirements.

Additionally, the grooved or finned rolls hereof, being in direct contact with and supporting the wire, realize the desirable generation of only low spouting forces with lessened formation disruption as the wire travels relative thereto.

The finned rolls preferentially will be of two types, a high fin roll used in areas where there is a large quantity of fluent material to cope with and a low n roll used in areas where the removal of water is not necessarily the primary desiderations but where the unique sealing arrangement is nonetheless requisite in serving the function of controlling the pressure drop through the labyrinthian passage delined by the seal.

Another object of the invention is to provide a labyrinth gland packing between a moving part and a iixed part of the machine to provide a barrier to the passage of gas and/ or fluid into certain portions of the machine. Here, one of the two relatively movable elements to be sealed carries a series of axially spaced annular bales or teeth or grooves or fins forming an annular comb and mounted thereupon or integral therewith and extending toward the other element, the comb being complemental to a linear comb mounted upon or integal with the other relatively movable element, which linear comb is interdigitated with the first named comb to form an effective labyrinth sealing of the interval between the two relatively rotatable members so as to insure against escape of gas or fluid either while the apparatus is stationary or rotary. That is, one comb extends toward and into the other one so that the space between the periphery of an annular seal element (normally on the rotor) and the adjacent complemental surface (normally on the stator) is as small as is practical. The high pressure gas or uid passing through this space at each tooth experiences a drop in pressure so that, after passing the successive teeth which constitute the seal, the pressure of the gas or fluid has fallen substantially to the pressure on the low pressure side of the seal.

As aforesaid, it is advantageous for the space between the free edge of the seal element and the adjacent surface to be as small as possible. In practice, however, the cornponents of all rotary machines are subject to distortion due to centrifugal forces, temperature variations, and acceleration and gyroscopic forces, all necessitating certain minimum clearances between the teeth of the combs so as to avoid excessive rubbing contact. In the labyrinth seal hereof, the glands may be constructed of relatively thin material in case weight reduction is a key consideration and, at the same time, I provide a stiff structure to withstand the distroting forces normally encountered in operation and it is a further object to provide a seal including seal elements which, should they come in contact with each other, will distribute the rubbing load over a relatively wide area and will, therefore, reduce the tendency to cause excessive wear at the surfaces.

In many cases, the distortion of one part may close the gap between the parts of the labyrinth seal and cause rubbing of the parts. This difficulty of course might be obviated by increasing the seal clearances, an unsatisfactory solution because the leakage of the seal increases. The present invention solves this problem by virtue of the novelty of the labyrinth seal design in that the seal is constituted by a non-rotating part mounted so that it can shift slightly in a plane transverse to the axis of the rotating part so that, if contact due to non-concentricity occurs the stationary seal part may be shifted to center itself and thus prevent the wearing away of the parts by rubbing which would otherwise occur and which would cause an increase in seal clearance.

The labyrinth seal portion of the invention is described in terms of its preferred embodiment in a papermaking machine and the advantages of this part of the invention will be recited in terms of this environment.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which I regard as my invention, it is believed that the characteristic features novel with the invention, as to its construction and purpose, will be better understood from a consideration of the following detailed description of a prefered embodiment forming a part of this specification, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatical elevational view of a preferred embodiment of a high speed paper forming section of a papcrmaking machine showing the endless wire belt and the forming and vacuum zones according to the structure of the invention, with the framework indicated in dot and dash lines;

FIG. 2 is a broken top plan view of the structure shown in FIG. 1 with the framework shown in solid lines;

FIG. 3 is an enlarged broken side elevational and part sectional view of a finned roll of the invention in sealing relation to a suction box side wall; and

FIG. 4 is a fragmentary sectional view of a modified form of finned roll in sealing relation to a suction box side wall.

Referring to the drawings, the machine generally comprises and endless paper forming wire band 10, called the wire, which follows an extended circuitous path through a main forming zone, generally indicated by 12, in which the stock slurry is delivered, and thence in seriatim through a plurality of vacuum zones, generally indicated by 14 as a primary vacuum zone, by 16 as a secondary vacuum Zone, and by 18 as a tertiary vacuum zone.

Endless wire is of wire mash, composed of fine wires made of metal such as bronze in the case of the warp wires and possibly brass in the case of the filler wires, which wire may vary in length, according to the machine size, as from a length of 60 to one of 100 or more, which may be of any width from under 36 to over 300", and which may rotate generally between and be cntrained about a plurality of rolls to be defined.

Preferably, the means for guiding wire 10 over the said extended circuitous and endless path which comprises a pair of generally horizontal runs or reaches of the wire at its upper and lower portions and an inclined reach or run of the wire leading from the lowermost horizontal run to the uppermost horizontal run and a declined reach or run leading from the uppermost horizontal run to the lowermost horizontal run, comprises a framework or structural member which is, for the purposes of the present invention, immaterial and may be constituted by a pair of spaced apart side frames 20, and a plurality of freely rotatable supporting rollers extending longitudinally between and strategically spaced around the side frames to more or less define substantially the oval shaped path of the wire and to perform the function of guiding the endless wire over the said oval shaped extended circuitous and endless path.

The wire is of a width slightly less than the spacing between the side frames and is guided over the rolls around the said path all in manner such that the structural member at its top, bottom and opposite ends is substantially enclosed by the wire which forms an endless perforate wall.

A breast roll 22 and a turning roll 24 are rotatably mounted in and extend between the side frames of the framework, the breast roll being located adjacent the leading end of the machine, and the turning roll being located adjacent the discharge end thereof. Said rolls 22 and 24 may be mounted on shafts 26 and 28 respectively journalled in the usual anti-friction or ball bearings mounted on bearing blocks, not shown, in the spaced side frames. A guide roll 30 is rotatably mounted in and extends between the side frames and its shaft 32 may be similarly journalled, and a stretch roll 34 is likewise rotatably mounted in and extends between the spaced side of the framework and its shaft 35 may be likewise similarly journalled in anti-friction or ball bearings suitably mounted on bearing blocks.

Means 36 of conventional design may be provided to adjust the positioning of the stretch roll for adjusting the tensioning of the wire, and additional adjustment means, in the form of cantilever support beams 38, may be provided for adjusting the positions of the breast roll and turning roll relative to the wire.

A plurality of grooved fin rolls or capillary rolls, now to be described, are rotatably mounted in and extend between the spaced side frames of the framework, each roll serving as the rotor of the labyrinth seal sealing between such rotor and a stator, as will be defined.

As shown in FIGS. 2 and 3, each finned roll is a straight-grooved roll of a type of capillary roll having annular straight walled grooves in a plane at right angles to the axis of the drum of the roll. The roll may comprise a metal core or shaft 42 covered or sleeved with a thick sheathing 44 of rubber or bronze or other resilient material in the outer periphery of which a plurality of longitudinally-spaced annular grooves 46 `are machined or otherwise formed so as each to be separated by annular lands or fins 48 allowing an outwardly-facing anti-friction facing defined along the circular zone represented by the line X which lens itself to being lubricated by the water.

On the other hand, the finned covering element may be of a very hard material lubricated by water such as the wood lignum vitae.

The finning on the roll may be otherwise comprised of a number of annular discs, connected by spacer rings of lower height and mounted upon the outer periphery of core or shaft 42 or may be comprised of a single unitary ring fixed to the core or shaft as by bolting or the like with the ring including a cylindrical peripheral portion bearing labyrinth seal ribs.

If desired, and as graphically represented in FIG. 2, the grooves in each succeeding roll may not be in alignment with those of the preceding roll but may be staggered, wherefor the grooves in one roll will not be directly in front of or behind the grooves in the roll immediately adjacent it, but will be offset from it.

The grooved rolls may -rotate in anti-friction bearings which may be of the roller or ball bearing type so as to help to land the rolls in the bearings relative the top of the framework.

The turning roll is normally driven by any suitable powe-r means and drives the wire which in turn rotates the breast roll, the guide roll, stretch roll, and finned rolls, or the various rolls may be otherwise rotated. If desired, the various rolls may be driven by a t-rain of gears keyed to the respective shafts, and to insure that all the rolls rotate in the same direction, idler gears may be provided between each of the main gears. The gears may be driven by any suitable arrangement, either from a rotating member on the machine or by a separate motor.

To prevent the respective shafts from twisting by the driving torque, auxiliary bearings (not shown) may be provided on the outside of the respective gears.

The framework is provided with an inlet means at its leading end for the discharge of stock onto an nclined portion of the wire at the forming zone upwardly of the breast roll and downwardly of a first grooved fin roll, to be further defined, so as to introduce the mixtu-re of pulp and water in a flow tangential to the direction of movement of the wire, as indicated by arrow a, and through a throat or narrow discharge outlet 62 leading froma stock supply (not shown).

If desired, a forming board 64, which alternatively may comprise suction boxes, may be placed in position at the forming zone under the wire where no or little water drains from the wire.

The rst or primary grooved fin roll 70 of a trio of high- finned rolls 70, 80 and 90, is disposed immediately adjacent and above for-ming board 64, with the wire being carried over the top of said primary grooved fin roll.

The second grooved fin roll 80 of the trio of high-finned rolls is disposed on the opposite side of rst roll 70 and in spaced relationship therewith.

A water deflector 72 may be disposed between first and second high-finned rolls 70` and 80 respectively.

Forwardly of second roll 80, the third grooved fin roll 90 of the trio of high-finned rolls is disposed.

A water deflector 82 may be disposed between second and third high- finned rolls 80 and 90 respectively.

Forwardly of third roll 90, a fourth grooved fin roll 100, preferentially of low lin type, is disposed.

A water deflector 92 may be disposed between highfinned roll 90 and low-finned roll 100 respectively.

First and second rolls 70 and 80 of the trio of highfinned rolls may be disposed in different horizontal planes with second roll 80 being in a plane above the plane of first roll 70, wherefore the wire is carried over the tops of said rolls and on an incline through what is defined as the primary vacuum zone 14.

Second, third and fourth rolls 80, 90 and 100 respectively are disposed in the same horizontal plane coincident with the plane of guide roll 32.

First and second rolls 70 and 80 respectively cooperantly define therebetween primary vacuum zone 14 below the plane of the wire stretched therebetween and enclosed by a pair of primary vacuum zone walls 112 and 114 extending tangentially and outwardly from opposite sides of a primary vacuum pipe 116, which Iwalls have outer upper free planar edges so configured as to serve as seats for the stators of the labyrinth seals between the respective of the primary and secondary rolls. That is, each of said rolls is sealed relative to the respective wall of the vacuum box by a seat of a labyrinth seal 118 (see FIG. 3), having grooves 120 and lands 122 which mate with the grooves and lands of respective rolls 70 and 80.

The finned rolls and labyrinth seals may be otherwise formed as shown in FIG. 4, wherein a roll having a thick sheathing 344 of rubber or bronze or other resilient material in the outer periphery of which a plurality of longitudinally-spaced annular grooves 346 having tapered side walls are machined or otherwise formed so as each to be separated by annular lands or fins 348 having tapered side walls, and mating with complemental grooves 320 and lands 322 provided in a labyrinth seal 318 secured to the upper edge of a vacuum zone wall 312.

Such tapering of the walls of the grooves and lands greatly facilitates machining operations. Sealing is accomplished by the pressure drop which occurs between the roll and the stationary wall.

Primary vacuum pipe 116 is connected to a suitable vacuum source, not shown, and the peripheral surface thereof between walls 112 and 114 is apertured or may be cut away to provide vacuum to the primary vacuum zone interior.

Second and third rolls 80 and 90l cooperantly define therebetween seconda-ry vacuum zone 16 below the plane of the wire stretched therebetween and enclosed by primary vacuum zone wall 114, a secondary vacuum zone wall 124 fixed to one side of and extending tangentially and outwardly from one side of a secondary vacuum pipe 126 and Xed at its outer free end to primary vac-num zone wall 114, and a secondary vacuum zone wall 128 extending tangentially and outwa-rdly from the opposite side of the pipe 126, to third roll `90. As `with walls 112 and 114, wall 128 has an outer free end edge serving as a seat for the stator of a labyrinth seal 118 having grooves and lands which mate with the grooves and lands of third roll 90.

Secondary vacuum pipe 126 is connected to a suitable vacuum source, not shown, and the peripheral surface thereof between walls 114, 122 and 124 is apertured or may be cut away, as with primary vacuum pipe 116-.

Third roll 90 and fourth roll 110 cooperantly define tertiary vacuum zone 18 below the plane of the wi-re stretched therebetween and enclosed by secondary vacuum zone wall 128, a tertiary vacuum zone wall 132 fixed to one side of and extending tangentially and outwardly from one side of a tertiary vacuum pipe 136 and secured to secondary vacuum zone wall 128 and a tertiary vacuum zone "wall 134 extending tangentially and outwardly from the opposite side of pipe 136. As with walls 112, 114 and 128, wall 134 has an outer free 'end edge serving as a seat for a labyrinth seal 118 having :grooves and lands which mate with the grooves and lands of fourth roll 100.

Tertiary vacuum pipe 136 is connected to a suitable vacuum source, not shown, and the peripheral surface thereof between walls 128, 132 and 134 is apertured or may be cut away, as with pipes 116 and 126.

The finned rolls will be of two types, namely, highfinned or low-finned, with the trio of rolls 70, and preferably being of the high fin type with the grooves between the lands or `fins thereof preferentially being in the order of about 1A" in width with the lands being about ls" in width and about 1" in depth, and with fourth roll and breast roll 22 being of the low fin type with the grooves between the lands or fins thereof preferentially being in the order of about 1A" in width, with the lands being about Ms" in width and about 1A in depth.

The outer periphery of each roll defines an outer surface which is a surface of revolution and which is coaxial with, parallel to and closely spaced from the outer surface of revolution of a wall of a vacuum zone supported by the structural member.

If desired, means may be provided for manually moving the non-rotating member of the seal so as to shift same slightly in a plane transverse to the axis of the rotating part so that, if contact due to non-concentricity occurs, the stationary seal part may be shifted to center itself and thus prevent the wearing away of the parts by rubbing which would otherwise occur and which would cause an increase in seal clearance.

To prevent end leakage between the respective rolls and the forming Zone and/ or the various vacuum zones, there may be provided at the free end of the rolls and each adjacent side frame a seal in the form of a packing gland, not shown, which is held in situ by any suitable means.

The openings under the two side edges of the endless wire above the top of the forming zone and between the rolls may be closed with sealing strips, not shown, which may be made of or covered with resilient material such as rubber.

Because the rolls have straight grooves at their ends under the edges of the endless belt, the sealing strips can be made to t into and across the outermost groove of each finned roll and thus make a continuous end seal between the rolls, the top of the forrning zone and the under edge of the wire.

Since the surfaces in the annular grooves are in a plane at right angles to the axes of these rolls, these surfaces give excellent support to the end sealing strips at each end of the forming zone against atmospheric pressure when there is a partial vacuum in that portion of the endless belt immediately above the top of the forming zone.

The stock formed on the wire is a thin continuous layer as it passes over the forming zone and the successive low vacuum zones, and is removed from the wire as by any of the conventional devices such as a pickup couch roll 250 having a pickup felt 252 entrained therearound.

The main forming zone may be open to the atmosphere, or be under vacuum.

The stock on the wire passes from the forming zone over the plurality of vacuum zones, with the endless wire being supported by the grooved fin-type rolls which also provide rotating partitions between the 'vacuum compartments.

The vacuum compartments are sealed by the labyrinth seals which mate with the grooves and lands of the iin rolls.

The vacuum compartments may also be equipped with water deflectors, as shown.

Low vacuum sources are permitted because the objectionable centrifugal forces inherent with forming devices which employ a drilled shell, such as a suction breast roll or a Rotoformer, are not set up within the machine.

The machine is mounted upon the pair of spaced cantilever support beams 38 whereby the entire machine may be cantilevered, facilitating wire changing. That is, the wire may be changed by cantilevering the entire machine and slipping the wire into position. The slack necessary for changing the wire may be obtained by adjusting the positioning of the stretch roll.

A vacuum source and exit in the form of a fan or the like, not shown, is provided in each vacuum pipe 116, 126` and 136.

Main forming compartment 12, provided rearwardly or inwardly of forming board 64, is bounded along its upper side by finned roll 70, vacuum zone walls 112 and 124 and by vacuum pipes 116 and 1216, and is bounded at its inner or rearward end by an upright wall 260 sealed at its upper end to -vacuum pipe 126. Forming compartment 12 is bounded along its lower side by an upwardly curved extension 262 of wall 260, by one of said cantilever support beams 38, and by breast roll 22.

Any suitable vacuum or exhaust means may be provided in a discharge orifice 264 of the forming compartment, or the compartment may be vented directly to atmosphere.

In operation, stock in the form of a brous slurry is delivered to the wire at forming board 64 where the stock is optionally subjected to vacuum at main forming compartment 12 to remove water therefrom. As the wire continues in its travel, it delivers the stock to the series of adjacent low vacuum zones 14, 16 and 18 defined by the spaced fin-type rolls, each such vacuum zone allowing the extraction of water from the web. From the last vacuum area 18, the formed web is delivered by the wire to pickup felt 252 running with pickup couch roll 250.

Herein, web formation is controlled by the use of low vacuum, same being important for porosity control and sheet formation. The low friction resistance over the vacuum areas, due to the labyrinth means between the finned rolls and the stationary zones, results in low driving horsepower requirements; the grooved rolls are in contact with and support the wire, resulting in low spouting forces with resultant lessened formation disruption.

A controlled drainage rate is permitted for controlled formation, due to the plurality of vacuum zones separately controlled, and the entire machine design permits the use of economical short wires which are easy to change because of the cantilever-type machine mounting.

Water in the stock is filtered through the wire mesh leaving the wet fibers on the upper planar surface of the wire, and the drainage water or white water is pumped back into circulation from the catch basins, not shown. The fibers deposited on the wire form a fiber web or sheet of a desired thickness which is taken off the wire by pickup couch roll 250 and transferred to pickup felt 252.

Secured in the side frames and connected to vacuum pipes 116, 126 and 136 are conduits, not shown, adapted to be connected to a source of vacuum for removing drainage or white water from the respective vacuum zone to recirculate-it to the stock supply. Any other suitable connection may be made to the side frames for drainage of the white water, it being realized that since the side frames are stationary, the connection of vacuum and drainage pipes to the interior of the vacuum compartments is greatly simplified as compared with corresponding connections to a rotating wire-covered drum in previous constructions. That is, in vie'w of the fact that the framework is stationary, with only the wire forming the periphery of the framework and the rolls rotating, it is possible, in simple Imanner, to apply suction to the under surface of the wire as it passes over the framework, because the pipes for supplying the suction do not have to pass through rotating parts with the consequent necessity of providing expansive seals for such connections.

It should be understood that further modifications may occur to those skilled in the art without departing from the spirit and scope of my invention, and that my invention is not limited to specific details of construction and arrangement thereof herein illustrated.

What I claim and desire to secure by Letters Patent of the United States is:

1. A high-speed web-forming machine for processing a fibrous stock slurry comprising, a travelling endless wire meshfa plurality of low vacuum compartments disposed below said endless wire mesh, partitions between adjacent vacuum compartments, a plurality of rotatable grooved tin-type rolls supporting the Wire mesh, the rolls forming upper sections of the partitions and the wall portions of the compartments forming lower sections of the partitions, and labyrinth seals for sealing the confronting rolls and wall portions, wherefore a low friction resistance is experienced over each of the vacuum areas so as to result in low driving horsepower requirements.

2. A high-speed web-forming machine as set forth in claim 1, including a rotatable grooved fin-type breast roll in running relationship with the endless wire mesh.

3. A high-speed web-forming machine as set forth in claim 2 wherein the groove formation in the breast roll and in certain of the fin-type rolls differs from the groove formation in others of the fin-type rolls.

References Cited UNITED STATES PATENTS 2/1926 Jones 162-373 2/1953 Campbell 162-373 U.S. Cl. X.R.

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