US3455780A - Suction cylinder mold partially wrapped by and endless,porous control member - Google Patents

Description

y 9 s. J. HAZARD, JR.. ETA!- 3,455,730

SUCTION CYLINDER OLD PARTIALLY WRAPPED BY A" ENDLESS, POROUS CONTROL MEMBER Filed July 11, 1966 United States Patent U.S. Cl. 162318 6 Claims ABSTRACT OF THE DISCLOSURE An improved paper forming device including a rotatable suction forming roll and a flexible stock control member such as a porous wire which is trained over a portion of the forming roll in wrapped engagement with a segment of the latter so as to define a nip therebetween, there being provided nozzle means for directing stock at the nip and also dewatering means disposed above the stock control member thus producing simultaneous dewatering from both sides of the stock.

The present invention relates to paper forming apparatus, and particularly to apparatus which utilizes a cellular suction forming cylinder or roll to form a continuous paper web from liquid stock suspension or furnish delivered to the periphery of the roll from a nozzle.

It is known to provide a cellular suction forming roll in place of the extremely long Fourdrinier section conventionally used in paper making machines. Such a suction forming roll comprises a rotatable cylindrical shell having a plurality of radial openings therein. A nozzle is employed to supply the stock suspension to a predetermined forming area on the surface of the rotating suction roll, and the major part of the water in the stock suspension is removed by suction means disposed inside of the forming roll, such water being largely discharged outwardly from the forming roll by centrifugal force after the portion of the roll containing the water has passed beyond the forming area and beyond the eifect of the vacuum section within the roll. In this manner, a continuous web of paper is formed on a Fourdrinier wire on the surface of the suction forming roll and is subsequently removed by a suction pick-up or couch roll over which a pick-up felt is trained.

A cylinder sheet forming apparatus of the type described above is shown in Ostertag et al. Patent 2,418,600 wherein a traveling Fourdrinier wire is trained over a suction forming roll or breast roll, and the stock suspension is delivered to the Fourdrinier wire at an area where the latter is directly supported by the forming roll. Other types of cylinder sheet forming apparatus are disclosed in the copending applications of Sherwood G. Holt, Ser. No. 3l5,033, filed Oct. 9, 1963, now Patent No. 3,321,360, and Ser. No. 543,268, filed Apr. 18, 1966, now Patent No. 3,352,454, both of which are assigned to the assignee of the present invention. In the latter two applications there is described a suction forming roll including a Fourdrinier wire on the form of a sleeve which is intimately engaged over the periphery of the roll.

In the above-mentioned copending application of Sherwood G. Holt, Ser. No. 315,033, now Patent No. 3,321,360, there is described a cylinder-type paper forming device wherein the nozzle which delivers the stock suspension to a forming area on the suction forming roll has an upper lip which extends for a considerable distance over the forming area on the periphery of the forming roll so that substantially all of the formation of the paper web occurs under the extended upper lip of the nozzle.

3,455,780 Ice Patented July 15, 1969 Thus, control of the stock during formation of the web is efiected substantially entirely by the upper nozzle lip in combination with the forming roll. In the apparatus described in the other copending application of Sherwood G. Holt, Ser. No. 543,268, now Patent No. 3,352,454, a substantial portion of the extended upper nozzle lip is eliminated and replaced by an endless flexible stock control member which is movable at the peripheral speed of the forming roll and is trained over guide means which maintain an operative portion of the length of the stock control member in engagement or wrapping relation with a segment of the periphery of the rotatable forming roll in an area between the end of the nozzle upper lip and the pick-up roll. Accordingly, in the latter embodiment, partial formation of the web occurs in an initial forming zone under the nozzle upper lip, and further formation occurs in a second forming zone under the moving stock control member and immediately adjacent the first forming zone.

It is a primary object of the present invention to provide a cylinder-type paper forming device which provides increased control of the stock in an initial forming area where the stock first contacts the forming roll surface.

In furtherance of the foregoing object, we provide paper forming apparatus including a rotatable suction forming roll, and in combination therewith we provide an endless flexible stock control member of the general type mentioned above, the stock control member being driven over guide means which hold a portion of its length in engagement with a segment of the periphery of the forming roll. Moreover, in order to provide increased control over the stock suspension as soon as the same contacts the forming roll surface, we provide a nozzle wherein the upper lip portion is approximately coextensive with the lower lip portion, and such nozzle is positioned with the end thereof in close proximity to the moving stock control member. In other words, the nozzle has no projecting or overhanging upper lip, and it simply delivers the stock suspension to a nip formed between the suction forming roll and the endless stock control member in an area proximate where the latter initially contacts the forming roll. Consequently, the formation of the stock after it first contacts the forming roll occurs substantially entirely under the moving stock control member, in contrast with the prior structures described hereinabove where formation occurs entirely or partially under an extended upper lip of the nozzle.

We further provide suction means immediately above the moving stock control member proximate the end of the nozzle. In this manner, as the stock suspension is initially delivered to the forming drum it is conducted between the periphery of the drum and the moving stock control member, and the stock is simultaneously subjected to dewatering means inside of the forming roll and oppositely disposed dewatering means above the stock control member. Such an arrangement efiects maximum control of the stock during formation of the paper web, and such control begins substantially immediately upon contact of the stock with the forming roll.

The foregoing and other objects and advantages of the invention will be apparent from the following description thereof.

Now in order to acquaint those skilled in the art with the manner of practicing and utilizing our invention, we shall describe, in conjunction with the accompanying drawing, a preferred embodiment of the invention.

The drawing is a side elevational view, partly broken away, illustrating a cylindrical paper forming device constructed in accordance with the present invention.

Referring now to the drawing, there is shown a rotatably mounted cylindrical suction forming roll indicated generally at 10 comprising a cylindrical shell 12 having a plurality of closely spaced radial holes or cells 14 formed therein. A plurality of circumferentially spaced longitudinal spacer strips 16 extend along the outside of the cylindrical shell 12 and support a foraminous surfacing material or the like (not shown in detail) over which a wire sleeve 18 is mounted. If desired, a traveling Fourdrinier wire could be trained over the forming roll as shown in the abovementioned Ostertag et al. patent, but it is preferred that the wire comprise a sleeve which thus constitutes the peripheral surface of the forming roll.

Within the rotatable cylindrical shell 12 there is positioned a stationary tubular member 20 which together with a pair of radial partition walls 22 and 24 defines a suction box assembly or vacuum chamber to assist in the dewatering of the stock suspension which is supplied to the wire surface 18 of the suction forming roll. The radial partitions 22 and 24 extend the full length of the forming roll 10 and are provided at their radially outer ends with sealing strips 26 and 28. Additional partition walls 30 and 32 having sealing strips 34 and 36 may also be provided, the latter partitions being circumferentially adjustable and serving to divide the vacuum chamber into several compartments which may be subjected to varying degrees of vacuum.

Norm-ally, the first compartment between the partitions 24 and 32 will be subjected to a somewhat lower vacuum than the other compartments within the forming roll 10, due in part to the fact that the stock suspension is under pressure as it leaves the nozzle 40, and the latter pressure will itself tend to force the water into the openings 14 in the periphery of the roll 10. Moreover, in some instances it may even be found desirable to provide a low positive pressure within the first compartment between the partitions 24 and 32 to partially offset the pressure provided by the nozzle 40. Accordingly, while the chambers or compartments within the roll 10 between the two outermost partitions 22 and 24 are referred to herein as vacuum chambers, and while most of the compartments will be in fact be subjected to a vacuum, it should be understood that in certain applications a small positive pressure may be created in one or more of the compartments, particularly in the area of the nozzle outlet. For a more detailed description of the cellular suction forming roll 10, reference is made to the above-mentioned copending application of Sherwood G. Holt, Ser. No. 315,033, now Patent No. 3,321,360.

A nozzle 40 comprises an upper nozzle lip 42 and a lower nozzle lip 44, and it will be seen that the upper and lower nozzle lips are coextensive in the sense that they terminate together, such an arrangement being in contrast with various prior art devices where the upper lip extends well beyond the lower lip so as to exert control over the stock after it engages the forming roll. In the embodiment being described, the nozzle 40 is substantially straight and is approximately tangential to the forming roll 10. However, it should be understood that if desired only the outlet end of the nozzle need be approximately tangential to the forming roll, and the inlet end of the nozzle may join with the outlet end thereof through a curved nozzle section. Moreover, while no means for adjustment of the upper lip 42 relative to the lower lip 44 is provided in the embodiment illustrated, the end of the upper lip may comprise a movable section which is capable of adjustment relative to the lower lip. The overall nozzle assembly 40 may also be pivotally mounted or otherwise adjustable, as shown for example in the abovementioned copending application of Sherwood G. Holt, Ser. No. 315,033, now Patent No. 3,321,360. The stock nozzle 40 is supplied at its inlet 46 with stock suspension through the usual supply pipes and through transition pieces which spread out the flow into a wide thin pattern of uniform dimensions and density across substantially the entire axial length of the roll 10, the stock suspension being delivered by the nozzle to the wire surface 18 on the forming roll.

A stock control member in the form of a movable porous top wire or fabric 48 is provided in order to control the stock during formation of the paper web. The stock control member may be made from conventional Fourdrinier wire, or if desired it may be made from various types of porous fabric, for example a synthetic fiber fabric. There is shown a stock control assembly 50 including a supporting frame 52 comprised of interconnected frame elements 54, 56, 58 and 60, the frame 52 being pivotal about a pair of trunnion shafts such as shown at 62. The pivotal position of the frame 52 on the trunnions 62 may be determined by one or more adjustable jacks or the like (not shown) which extend from the frame 52 to a fixed supporting member. A plurality of rolls or pulleys are rotatably mounted on the supporting frame 52 in order to support and drive the endless stock control member 48 which is trained over a portion of the periphery of the forming drum 10 adjacent the end of the nozzle 40 and thereby controls the stock during formation of the continuous paper web. Thus, a drive roll 64 is rotatably mounted on a shift 66 supported by lugs 68 extending from the lower end of the frame element 56. The drive roll 64 engages the outside of the endless stock control member 48, and the roll 64 is driven by a variable speed drive (not shown) so as to move the stock control member ata desired speed, preferably the same as the peripheral speed of the forming roll 10. A guide roll or pulley 70 is rotatably mounted on a shaft 72 supported by lugs 74 which project from the frame element 60, and the roll 70 engages against the inside of the stock control member 48 to guide the same. Above the guide roll 70 there is mounted a stretch roll 76 which is rotatable on a shaft 78, the latter being supported on a carriage 80 which is slidably adjustable along one or more guide rods 82. The stretch roll 76 is engaged against the inside of the endless stock control member 48, and the carriage or slide 80 may be adjustably positioned on the guide rods 82 in order to apply a predetermined desired tension to the stock control member.

A pivotally mounted arm 84 serves to support one end of a shaft 86 on which an adjustable wire control roll or guide roll 88 is rotatably mounted. The other end of the shaft 86 is mounted in a universal spherical hearing or the like (not shown), and the pivot arm 84 has one end pivotally mounted to the frame element 56 by means of a pin 90. Accordingly, movement of the arm or lever 84 about its pivot pin 90 will cause the roller shaft 86 to pivot about the one end thereof which is universally mounted. An air cylinder 92 has one end connected to the arm 84 and its other end connected to the upper end of the frame element 56, and a tension spring 94 extends between the arm 84 and the frame element 58. Thus, by controlling the supply of air to the air cylinder 92, and thereby varying the length of such air cylinder, it is possible to vary the position of the arm 84 and in this manher control the orientation of the shaft 86 and wire control roller 88.

The roll 88 engages against the outside of the endless stock control member or wire 48, and the position of the roll 88 is continuously adjusted as required by means of the air cylinder 92 in order to control or guide the movement of the stock control member 48. More specifically, a movable feeler or sensing member (not shown) engages the moving stock control member 48 and senses lateral or transverse movements of the latter. The feeler or sensing member is associated with valve means (not shown) so as to control the air supply to the air cylinder 92 in accordance with lateral position of the stock control member relative to the roll 88. Thus, whenever the stock control member 48 tends to move from a centered position on the roll 88, the orientation of the roll is varied in order to maintain the member 48 in a centered position on the roll. In this manner, the moving endless stock control member or wire 48 is continuously maintained in a proper centered position on the roll 88 and on the various other guide and tension rolls over which it travels.

The lower portion of the stock control member 48 is trained over a guide roll '96 and a suction box 98 which together cause the stock control member to partially wrap or engage on a segmental portion of the periphery of the forming roll 10. The guide roll 96 is rotatably mounted on a shaft 100 supported on a pair of lugs 102 which project downwardly from a mounting bracket 104. The suction 'box 98 is supported in any suitable manner such as from a frame element 106, and it is positioned in close proximity to the periphery of the forming roll and immediately adjacent the end of the nozzle 40. It should be understood that the drive roll 64, the several guide rolls 70, 76, 88 and 96, the suction box 98, and the endless stock control member 48, all extend for substantially the full length of the suction forming roll 10, and the portion of the endless stock control member 48 between the guide roll 96 and the suction box 98 is held in partially wrapped relation on a segment of the periphery of the roll 10 so as to control the paper web being formed thereon from the stock suspension supplied by the nozzle 40. After the paper web is formed on the wire surface 18 of the forming roll 10, the web is couched off of the forming roll by a pickup felt 108 which is trained over a pick-up roll 110 and a guide roll 112.

As stated earlier herein, and as described more fully in the copending application of Sherwood G. Holt, Ser. No. 315,033, now Patent No. 3,321,360, the forming roll 10 effects dewatering of the stock suspension and resulting paper web due to either or both the suction applied at the wire side or bottom side of the web and the pressure created by the nozzle 40 which causes the water to enter the radial openings 14 in the roll. However, in accordance with the present invention it is possible to effect additional dewatering by means of the suction box 98, such dewatering occurring during initial formation of the Web as soon as the stock suspension contacts the periphery of the forming roll 10. It will be seen that the bottom of the suction box 98 adjacent the periphery of the forming roll 10 and immediately inside of the stock control member 48 comprises a perforate member 113 having a plurality of openings 114 so as to permit water passing up through the porous stock control member 48 to be drawn into the suction box and thereby removed. In addition, in the preferred embodiment being described, a pair of foils or scoops 116 and 118 are positioned in close proximity to the periphery of the roll 10 immediately above the endless stock control member 48 between the suction box 98 and the guide roll 96. Such foils also serve to remove water which moves up through the porous stock control member 48.

The stock suspension delivered by the nozzle 40 may for example constitute 1% solids, whereas the stock must be dewatered to approximately 15% solids by the time the web reaches the pick-up roll 110. Accordingly, if it be assumed that the apparatus is running at approximately 1900 feet per minute, then in the embodiment being described the sheet must be dewatered from 1% solids to 15% solids in less than 0.13 second, which is roughly equivalent to removing 43 gallons per minute per square foot of forming surface. One of the important advantages of the present invention is that it permits simultaneous dewatering of the stock suspension and resulting paper web from both the bottom or wire side of the web and the top or felt side thereof, and it permits such simultaneous dewatering from both above and below to be initiated approximately at the time the stock suspension first contacts the periphery of the forming roll 10. Such an arrangement thus differs from those devices where formation occurs substantially entirely under an extended upper lip of the nozzle, or where formation occurs first in an initial forming zone under an upper nozzle lip and thereafter in an adjacent secondary forming zone defined by a segment of the periphery of the roll 10 and a stock control member which is partially wrapped thereon.

In accordance with the present invention, the upper lip 42 of the nozzle is substantially coextensive with the lower lip 44 thereof, and approximately at the time the stock suspension first engages the periphery of the roll 10 its formation is controlled by the roll 10 and the stock control member 48. Moreover, as previously stated, the operative portion of the stock control member 48 and the suction box 98 are both closely adjacent the outlet end of the nozzle 40 thereby permitting dewatering from above and below during the initial formation of the web substantially immediately after the stock suspension contacts the periphery of the forming roll. By thus providing for a controlled rate of water removal in two opposite directions substantially as soon as the stock suspension contacts the roll 10, the apparatus described herein permits the maximum possible control of the stock during the initial formation of the web. In addition, the elimination of any extension on the upper nozzle lip beyond the area where the stock suspension first contacts the forming roll 10 has the further advantage that there is no possibility of foreign particles in the stock suspension being caught in a restricted area between the forming roll and the tip of the top lip.

We claim:

1. A device for forming a paper web comprising, in combination, a rotatable suction forming roll, a flexible stock control member having an operative portion of its length held in Wrapped engagement with a segment of the periphery of said forming roll so as to define a nip at the area where said stock control member first engages said forming roll periphery, said stock control member being continuously moved in the same direction as the periphery of said forming roll, stock supply means for delivering stock suspension to the periphery of said forming roll, said supply means being directed substantially at said nip so that said stock suspension will first engage said forming roll periphery approximately at said nip and will immediately pass into a forming zone wherein it is controlled by said stock control member, and dewatering means disposed immediately above said operative portion of said stock control member in proximity to said nip whereby when said stock suspension first contacts said forming roll and enters said nip between said forming roll periphery and said stock control member, simultaneous dewatering of said stock will occur during initial formation of said web both by said forming roll which acts on one side of the web and by said dewatering means which acts above the stock control member at the opposite side of the web.

2. The device of claim 1 wherein said dewatering means comprises suction means.

3. The device of claim 1 where said stock supply means comprises a stock supply nozzle having substantially coterminous upper and lower lip portions which both terminate in proximity to said nip, and Where said dewatering means comprises suction means.

4. The device of claim 3 wherein said suction means comprises a suction box.

'5. The device of claim 4 wherein additional water removal means comprising scooping means is mounted immediately over said operative portion of said stock control member in spaced relation to said suction box.

'6. In a device for forming a paper web including a rotatable suction forming roll and a flexible stock control member having an operative portion of its length held in wrapped engagement with a segment of the periphery of the forming roll so as to define a nip at the area where the stock control member first engages the forming roll periphery, said stock control member being continuously moved in the same direction as the periphery of the forming roll, the improvement comprising, in combination, a stock supply nozzle having substantially coterminous upper and lower lip portions which both terminate in proximity to said nip for delivering stock suspension to the periphery of the forming roll, said stock supply nozzle being directed substantially at said nip so that said stock suspension will firse engage the forming roll periphery approximately at said nip and will immediately pass into a forming zone where it is controlled 'by said stock control member, and dewatering means disposed immediately above the operative portion of the stock control member in proximity to said nip, whereby when said stock suspension first contacts the forming roll and enters said nip, said dewatering means will effect dewatering of the stock from im- UNITED STATES PATENTS 2,911,039 11/1959 Hornbostel et al. 1623 17 XR 3,056,719 10/ 1962 Webster 162318 XR S. LEON BASHORE, Primary Examiner 10 RICHARD H. TUSHIN, Assistant Examiner U.S. Cl. X.R.

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