Method and apparatus for forming a paper or tissue web Number:7,101,462 from the United States Patent and Trademark Office (PTO) owispatent

Title: Method and apparatus for forming a paper or tissue web

Abstract: A method and apparatus for transferring a vibrational force to the wire of a papermaking machine in order to re-align the fibers of the web forming on the wire or to clean press section felts. In some embodiments, the apparatus is a vibrational device including at least one vibration-inducing mechanism, a vibrational head coupled to the vibration-inducing mechanism for vibrating the wire, and a dampening mechanism coupled between the vibrational head and the vibration-inducing mechanism.

Patent Number: 7,101,462 Issued on 09/05/2006 to Bricco,   et al.

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Inventors:	Bricco; Michael J. (Larsen, WI), Reynebeau; Dale J. (Little Chute, WI)
Assignee:	Vibre-Tech, LLC (Little Chute, WI)
Appl. No.:	10/646,367
Filed:	August 22, 2003

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	10027507	Dec., 2001	6702925

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Current U.S. Class:	162/355 ; 162/351; 162/354
Current International Class:	D21F 1/20 (20060101); D21F 1/18 (20060101)
Field of Search:	162/308-310,312-314,289,351-356,348,208-211,363-366,374 209/920 366/127 134/1

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	WO97/30213		Aug., 1997		WO

Other References

US 6,134,809, 10/2000, Stipp (withdrawn) cited by other . "Forming Section Maintenance"; Beloit Corporation (1 page). cited by other . Calkin, Modern Pulp and Paper Making, 3.sup.rd Ed., (1957), Reinhold Publishing Corp., p. 312-313. cited by other.

Primary Examiner: Hug; Eric
Attorney, Agent or Firm: Michael Best & Friedrich

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Parent Case Text

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CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No. 10/027,507, now U.S. Pat. No. 6,702,925, filed on Dec. 21, 2001, the entire disclosure of which is incorporated herein by reference.

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Claims

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We claim:

1. A vibrational device for use with a papermaking machine having a wire, the vibrational device comprising: at least one vibration-inducing mechanism; a vibrational head coupled to the at least one vibration-inducing mechanism and movable to impart a vibrational force to the wire, the vibrational head having a support and a vibrational element coupled to the support and positionable adjacent the wire, the vibrational element having a surface substantially facing the wire and across which the wire passes during operation of the papermaking machine; and at least one dampener coupled between the vibration-inducing mechanism and the vibrational element.

2. The vibrational device of claim 1, wherein the at least one dampener comprises a conduit containing fluid.

3. The vibrational device of claim 2, wherein fluid pressure in the conduit is adjustable.

4. The vibrational device of claim 1, wherein the at least one dampener is located between the vibrational element and the support of the vibrational head.

5. The vibrational device of claim 4, wherein the at least one dampener comprises a conduit containing fluid.

6. The vibrational device of claim 1, wherein the at least one dampener comprises elastomeric material.

7. The vibrational device of claim 1, wherein the vibrational element is slidably coupled to the support.

8. The vibrational device of claim 7, wherein the support includes at least one T-shaped member by which the vibrational element is coupled to the support.

9. The vibrational device of claim 1, wherein the vibrational element is coupled to first and second supports positioned end-to-end in a cross-machine direction of the papermaking machine, each support coupled to and vibrated by a respective vibration-inducing mechanism.

10. The vibrational device of claim 9, wherein a machine-direction width of the vibrational element is greater than a machine-direction width of each one of the first and second supports.

11. The vibrational device of claim 9, wherein the at least one dampener extends in the cross-machine direction along at least part of each of the first and second supports.

12. The vibrational device of claim 9, wherein: the first and second support members have a first combined length in a cross-machine direction of the wire; and the at least one dampener extends along at least a majority of the first combined length of the first and second support members.

13. The vibrational device of claim 9, wherein at least one of the vibration-inducing mechanisms is controllable independently of another of the vibration-inducing mechanisms to adjust vibrational forces between different supports.

14. The vibrational device of claim 1, further comprising a feedback control system adapted to adjust the frequency of the at least one vibration-inducing mechanism.

15. The vibrational device of claim 14, wherein: the vibrational head includes at least two supports positioned end-to-end in a cross-machine direction; and the feedback control system includes a controller and at least two accelerometers each coupled to a respective support of the at least two supports.

16. The vibrational device of claim 1, wherein the at least one vibration-inducing mechanism is pneumatically powered.

17. The vibrational device of claim 1, wherein: the vibrational head further includes a secondary support; and the at least one dampener is coupled between the support and the secondary support.

18. The vibrational device of claim 17, wherein the support has at least one connector positioned for coupling the vibrational element to the support.

19. The vibrational device of claim 18, wherein the at least one connector establishes a sliding connection between the vibrational element and the support.

20. The vibrational device of claim 17, wherein at least one of the vibrational element and the secondary support includes a recess into which the at least one dampener is received.

21. The vibrational device of claim 20, wherein the at least one dampener is secured within the recess.

22. A vibrational device for use with a papermaking machine having a wire, the vibrational device comprising: first and second vibration-inducing mechanisms; and a vibrational head including a vibrational element and first and second supports, the first and second supports coupled to and driven by the first and second vibration-inducing mechanisms, respectively, the vibrational element coupled to and driven by the first and second vibration-inducing mechanisms via the first and second supports to transmit vibrational force to the wire, the first vibration-inducing mechanism controllable independently of the second vibration-inducing mechanism.

23. The vibrational device of claim 22, further comprising at least one dampener coupled adjacent at least one of the vibrational element and the first and second supports.

24. The vibrational device of claim 23, wherein the at least one dampener is a conduit containing fluid.

25. The vibrational device of claim 24, wherein fluid pressure in the conduit is adjustable.

26. The vibrational device of claim 22, wherein the vibrational element spans across a seam between the first and second supports.

27. The vibrational device of claim 26, wherein the vibrational element spans across at least a majority of each of the first and second supports.

28. The vibrational device of claim 23, wherein the at least one dampener comprises elastomeric material.

29. The vibrational device of claim 1, wherein the vibrational element is slidably coupled to the first and second supports.

30. The vibrational device of claim 29, wherein each of the first and second supports includes at least one T-shaped member by which the vibrational element is coupled to the first and second supports.

31. The vibrational device of claim 23, wherein: the first and second supports extend a first combined length in the cross-machine direction; and the at least one dampener extends at least a second length in the cross machine direction, the second length being substantially the same length as the first combined length.

32. The vibrational device of claim 22, further comprising a feedback control system adapted to adjust the frequency of the first and second vibration-inducing mechanisms.

33. The vibrational device of claim 32, wherein: the first and second supports are positioned end-to-end in a cross-machine direction; and the feedback control system includes a controller and at least two accelerometers coupled to the first and second supports.

34. The vibrational device of claim 22, wherein the at least one vibration-inducing mechanism is pneumatically powered.

35. The vibrational device of claim 22, wherein at least one dampener is coupled between the vibrational element and connectors of the first and second supports.

36. The vibrational device of claim 22, further comprising a secondary support coupled to the vibrational head, wherein at least one dampener is coupled between the support and the secondary support.

37. The vibrational device of claim 36, wherein at least one of the vibrational element and the secondary support includes a female recess into which the at least one dampener is received.

38. The vibrational device of claim 37, wherein the at least one dampener is secured within the recess.

39. The vibrational device of claim 22, wherein a machine-direction width of the vibrational element is greater than a machine-direction width of each one of the first and second supports.

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Description

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FIELD OF THE INVENTION

This invention relates generally to forming a paper or tissue web, and more particularly to apparatuses and methods for improving the fiber distribution within a paper or tissue web.

BACKGROUND OF THE INVENTION

Paper and tissue are typically manufactured in a continuous sheet on a papermaking machine. One of the most common papermaking machines is the Fourdrinier machine. Fourdrinier machines generally include at least three sections: a wet-end section, a press section, and a dryer section. The wet-end section, which can be 40 to 100 feet in length, is also referred to as the forming section or the Fourdrinier table. In the wet-end section, stock flow is transferred from a headbox onto a moving, endless belt of wire-mesh screen, referred to as the Fourdrinier wire, or simply as the "wire." Stock flow is normally a combination of wood fibers, fines and fillers, chemical additives such as bonding agents, and water. Wood fibers typically range in length from 400 to 7,000 microns and in width from 20 to 100 microns, depending on the species of the wood. Stock flow typically has a liquid consistency of 99 percent and a fiber consistency of approximately 0.2 to 1 percent (although other fiber consistencies are possible), depending on the grade and weight of the paper or tissue being manufactured.

The function of the headbox is to distribute stock flow with a uniform fiber distribution to the wire in order to produce a sheet of paper having uniform properties across the width of the wire (cross-machine direction), along the length of the wire (machine direction), and through the cross-section of the sheet of paper (Z direction). The headbox distributes stock flow to the wire at an angle other than absolute tangent, referred to as the angle of impingement. If the angle of impingement is steep, i.e., close to absolute tangent, the arrangement of the headbox is referred to as pressure forming. If the angle of impingement is shallow, i.e., not close to absolute tangent, the arrangement of the headbox is referred to as velocity forming.

The wire runs over a breast roll, which is usually located under the headbox. The wire is typically not a permanent part of the papermaking machine and requires periodic replacement. One condition leading to premature failure of the wire is the plugging of the openings in the porous wire by the fibers, fines, and fillers of the web being transported by the wire. Normally, the wire is a delicate, finely woven metal or synthetic fiber cloth that allows for drainage of the water, but retains most of the fibers. The strands of the wire are commonly made of finely drawn and woven, annealed bronze or brass.

After the stock flow is delivered from the headbox to the wire in the wet-end section of a Fourdrinier machine, the fibers are initially held in free suspension within the water as relatively mobile individual fibers or as part of a network, referred to as a floc. The fibers and flocs in the stock flow begin to form a wet sheet of matted pulp, referred to as an embryonic web. While not subscribing to any particular manner in which the embryonic web is formed, normally either bonding agents in the stock flow cause an electro-chemical bond or the bond is produced through physical entanglement. The embryonic web forms as the fibers and flocs in free suspension begin to settle in layers on the wire. Ideally, the fiber distribution within the web would be consistent in the cross-machine direction, the machine direction, and the Z direction. However, due to gravitational forces, the bottom-most layers of fibers that settle directly on the wire are typically more dense than the upper-most layers of fibers. The web normally has boundary layers (i.e., the two external layers of the web, such as the bottom-most layer of fibers that settles directly on the wire and the upper-most layer of fibers) and internal web fibers (fibers in the layers of the web between the two external layers of fibers). The web may consist of approximately 2 to 100 layers of fibers.

In order to assist in the formation of the embryonic web, as the wire moves away from the headbox, various suction devices can be used to drain water from the stock flow. The suction devices in the Fourdrinier machine typically include a series of stationary blades or foils. The stationary foils remove water from the stock flow by creating a vacuum on the downstream side of the blade where the wire leaves the blade surface. As the wire moves across a series of stationary foils, the downstream side of each stationary foil creates a vacuum that pulls water from the stock flow, while the upstream side of each stationary foil pulls the water off of the wire. Some of the wood fibers, fines, and fillers are pulled off of the wire along with the water being pulled off of the wire. The amount of fibers, fines, and fillers that are retained on the wire while the water is being pulled off of the wire is referred to as retention.

Once the wire passes over the stationary foils, the wire normally passes over a drive roll or couch roll, over a series of return rolls, and back to the breast roll. At the end of the wet-end section of the Fourdrinier machine, the web can have a water consistency of approximately 80 percent and a fiber consistency of approximately 20 percent. At this point, the web can normally support its own weight. Other water and fiber consistencies are also possible at this point for enabling the web to support its own weight.

Next, the web can be transferred from the wet-end section of the Fourdrinier machine to the press section at the couch roll. The wet web of paper is normally transferred from the wire of the wet-end section to a screen. The screen can be a woolen felt screen, referred to as a felt, acting as a conveyor belt to carry the web through the press section. The felt is typically porous media that provides space and channels for water removal. The felt can also act as a textured cushion or shock absorber for pressing the moist web without crushing the web. The texture and character of the felt varies according to the grade of the paper being made. The felt normally carries the web through two or more press rolls, which mechanically squeeze water from the web. A variety of suction devices, one of which is commonly referred to as a uhle box, can also be used to remove water from the felt. The press rolls often consist of a steel or cast iron core covered by a bronze or stainless steel inner shell and an outer rubber shell. At the end of the press section of the Fourdrinier machine, the web typically has a consistency of approximately 40 percent water and 60 percent fiber, although other web consistencies at this stage are possible.

After the press section, the web can be transferred to fabric dryer felts that carry the web through the dryer section. The dryer felts are most commonly constructed of a highly permeable cotton blend or open-mesh fabric. The web is normally held firmly against a number of steam-heated cylinders or drums by the dryer felts in order to evaporate the remaining water. As the web passes from one cylinder to another, first the felt side and then the web side are pressed against the heated surfaces of the cylinders. In addition, hot air may be blown onto the web and between the cylinders to vaporize water from the web. At the end of the dryer section, the completed web typically has a consistency of approximately 1 to 10 percent water and approximately 90 to 99 percent fiber, although other web consistencies are possible at this stage.

The quality of the paper web produced in the papermaking process depends in part on the orientation of the fibers and the consistency of fiber distribution when the embryonic web is formed in the wet-end section of the Fourdrinier machine. The orientation of the fibers within the embryonic web first depends on the distribution of the stock flow to the wire by the headbox. In a pressure forming arrangement of the headbox, the web's boundary layer fibers often become impregnated in the wire. When the web is later transferred from the wire, the boundary layer fibers impregnated in the wire are pulled from the web, leaving small holes in the web. These small holes in the web result in a web that is not as smooth on one side as it is on the other (often called the "phenomena of two-sidedness"). Also, in a pressure forming arrangement, the web's internal layer fibers become forcibly and sporadically misaligned. In a velocity forming arrangement of the headbox, the sheet is formed through a thickening mechanism. This thickening mechanism is due in part to gravitational forces pulling the fibers and the water down through the wire, which causes the bottom-most layers of fibers that settle directly on the wire to be more dense than the upper-most layers of fibers. This high-density layer prevents fibers, fines, and fillers from being pulled through the wire (i.e., higher retention). This high-density layer also prevents water from draining through the wire, resulting in two-sidedness. Both the phenomena of two-sidedness and the disparate orientation of internal layer fibers reduce the quality of the finished paper web.

As water is mechanically squeezed from the paper web in the press section, fines, fillers, and fibers become impregnated in the felt carrying the paper web. The fines, fillers, and fibers plug the felt's water removal channels, resulting in the felt becoming less efficient in removing water from the paper web. As the felt in the press section becomes less efficient in removing water from the web, the dryer section must carry the burden of removing more water from the paper web.

A long-standing problem with papermaking machinery and processes is the large amount of energy required to run the machinery and to produce paper in such processes. A significant portion of this energy is consumed within the dryer section of the papermaking machine. Paper webs having poor fiber formation require significantly more heat to dry than paper webs with good fiber formation and distribution. Therefore, the problems described above regarding fiber misalignment and poor fiber distribution result in paper that requires more energy to dry and that is more costly to produce.

In addition, paper having poor fiber formation is typically lower in machine direction tensile strength when compared with the same grade of paper with a more consistent fiber distribution. This may require expensive chemical additives to increase web strength and can require more sizing, coating, calendaring, and converting operations to produce an acceptable paper product. Improving fiber formation by using more highly refined stock fibers can help to address these issues, but at a significantly increased pulp cost.

In light of the problems and limitations described above, a need exists for a method and apparatus for increasing the quality and manufacturing efficiency of a finished paper web by reducing the phenomena of two-sidedness, improving the distribution of internal layer fibers in the web, lowering the cost of web production through reduced energy requirements, reducing the amount of chemical additives needed for acceptable web strengths, enabling the use of less refined or lower quality stock, improving the retention of fines and fillers within the web, and keeping the forming and press fabrics clean. Each embodiment of the present invention achieves one or more of these results.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a papermaking method and apparatus to improve the quality of a paper web by reducing the phenomena of two-sidedness, by improving the alignment and distribution of the fibers in the web, and by reducing the energy requirements of the papermaking process by increasing water removal from the web in the wet-end and press sections of the paper making machine. As used herein and in the appended claims, reference to a paper web is intended to refer to any type of paper or tissue web produced with a papermaking machine.

In some embodiments of the present invention, stock flow, including fibers and water, is discharged from a headbox onto a wire. A vibrational force is transferred to the wire in order to re-align the fibers. In addition, the water from the stock flow is drained to cause the fibers to form a web. The energy imparted to the wire by the vibrational force preferably causes the boundary layer fibers impregnated in the wire to be released from the wire. The energy imparted to the wire by the vibrational force also preferably causes release of internal layer fibers that have begun to form the embryonic web. The internal layer fibers can then re-align and re-settle on the traveling wire in a more natural and uniform pattern. As the internal layer fibers re-settle, the fibers can penetrate into empty voids within the web. Preferably, the vibrational force is transferred to the wire of the papermaking machine before significant water removal takes place, i.e. during the formation of the embryonic web. In some highly preferred embodiments of the present invention, the vibrational force is transferred to the underside of a substantially horizontal wire, such as the wire of a Fourdrinier papermaking machine. In these and other embodiments, a vibrational force is transferred to the forming or press fabrics of the papermaking machine in order to release the fibers, fines, and fillers that have become impregnated in the forming or press fabrics. In such embodiments, the vibrational force can be used in conjunction with conventional suction devices, if desired, in order to maintain the cleanliness and water removal efficiency of the fabrics.

Some preferred embodiments of the present invention employ a papermaking machine vibrational device having a vibrational device frame, at least one vibration-inducing mechanism coupled to the vibrational device frame, and a vibrational head coupled to the vibration-inducing mechanism. Any number of such vibrational devices can be located adjacent to the web-forming wire, adjacent to the press felt, or adjacent to both the web-forming wire and the press felts for imparting vibration to the wire or press felt as described above. The vibrational head of the vibrational device preferably engages the wire or press felt of the papermaking machine to impart a vibrational force to the wire or press felt. In some embodiments, the vibrational device is positioned under the wire or press felt in an orientation perpendicular to the direction of travel of the wire or press felt. The vibrational device can span the entire width or substantially the entire width of the wire or press felt in order to impart the vibrational force to the entire width of the web.

In some embodiments of the present invention, the vibrational device frame is mounted to the papermaking machine frame. The vibrational device frame can have a truss network mountable to the papermaking machine frame and supporting the vibration-inducing mechanisms and the vibrational head under the wire or press felt. In some preferred embodiments, the vibrational device includes a vertical adjustment mechanism coupled to the truss network to allow for vertical adjustment of the vibrational device with respect to the wire or press felt.

The vibration-inducing mechanisms are preferably pneumatic, hydraulic, or electric mechanisms that transfer a vibrational force to the vibrational head and wire or press felt. Although any type of vibration can be transferred to the head (and wire or press felt) in this manner, the vibration is preferably high frequency and low amplitude. Preferably, the frequency and amplitude of the force transferred by the vibration-inducing mechanisms can be varied through the use of a solenoid valve or an amplifier, if desired. In some embodiments, the frequency and amplitude of the force transferred by each vibration-inducing mechanism can be varied independently, in order to impart different forces to different portions of the web. For example, the frequency and amplitude of the forces transferred by two or more vibrational devices spaced in the cross-machine direction can vary to generate different vibration frequencies and amplitudes across the wire or press felt in the cross-machine direction. Preferably, a sliding mechanism is used to couple the vibration-inducing mechanisms to the vibrational head, thereby enabling quick and easy vibrational head replacement (even during operation of the papermaking machine in some embodiments).

The vibrational head preferably includes a land area through which the vibrational force is transferred from the vibrational head to the wire or press felt. In some embodiments of the present invention, the land area includes an upstream portion which slopes vertically downward from the wire or press felt at a lead angle, so that the lead angle pushes water up into the wire or press felt when the vibrational head engages the underside of the wire or press felt. The land area can also include a downstream portion which slopes vertically downward from the wire or press felt at a relief angle, so that the relief angle induces a vacuum when the vibrational head engages the underside of the wire or press felt. In other embodiments of the present invention, the land area has a concave configuration.

In some highly preferred embodiments of the present invention, a lubrication shower is positioned within the wet-end section or within the press section of the Fourdrinier machine upstream from the vibrational device in order to lubricate the wire or press felt, in order to re-fluidize the fibers within the web before the fibers reach the vibrational device, and in order to minimize air entrapment in the nip (i.e., vacuum) formed between the traveling wire or press felt and the vibrating head.

The vibrational device according to some embodiments can include one or more dampening mechanisms coupled between, adjacent to, or in any suitable position with respect to the vibration-inducing mechanisms and the vibrational head. In some embodiments, the vibrational device can include two or more vibration-inducing mechanisms and a vibrational head including a single vibrational element and two or more support members. A vibration-inducing mechanism can be coupled to each one of the support members. In addition, a dampening mechanism can be coupled between the two or more support members and the single vibrational element.

Further objects and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described with reference to the accompanying drawings, which show a preferred embodiment of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in embodiments which are still within the spirit and scope of the present invention.

In the drawings, wherein like reference numerals indicate like parts:

FIG. 1 is a perspective view of a papermaking machine wet-end section having vibrational devices according to a preferred embodiment of the present invention;

FIG. 2 is side elevational view of the papermaking machine shown in FIG. 1;

FIG. 3 is a perspective view of a wire portion of the papermaking machine shown in FIG. 1;

FIG. 4 is a detail view of the papermaking machine shown in FIG. 1;

FIG. 5a is a front elevational view of a vibrational device used in the papermaking machine shown in FIG. 1, viewed from line 5--5 of FIG. 4;

FIG. 5b is a front elevational view of an alternative vibrational device according to the present invention, viewed from line 5--5 of FIG. 4;

FIG. 5c is a detail view of the vibrational device shown in FIG. 5a, used with the truss of FIG. 5b;

FIG. 5d is a detail side view of an alternative vibrational device according to the present invention;

FIG. 6a is a side elevational view of the vertical adjustment mechanism of the vibrational device illustrated in FIG. 5a, viewed from line 6a--6a of FIG. 5a;

FIG. 6b is a side elevational view of the vertical adjustment mechanism of the vibrational device illustrated in FIG. 5c, viewed from line 6b--6b of FIG. 5c;

FIG. 6c is a side elevational view of a vertical adjustment and isolation mechanism according to another embodiment of the present invention;

FIG. 7a is a cross-sectional view of the vibrational device shown in FIG. 5a, taken along line 7a--7a of FIG. 5a;

FIG. 7b is a cross-sectional view of the vibrational device shown in FIG. 5b, taken along line 7b--7b of FIG. 5b;

FIG. 7c is a cross-sectional view of the vibrational device shown in FIG. 5c, taken along line 7c--7c of FIG. 5b;

FIGS. 8a 8e are cross-sectional views of different embodiments of vibrational heads for a vibrational device according to the present invention;

FIG. 9a is a schematic representation of stock flow settling on a wire without a vibrational force;

FIG. 9b is a schematic representation of stock flow settling on a wire with a vibrational force;

FIG. 10 is a graph of the sheet properties of a paper sheet in the cross-machine direction (width) of the paper sheet;

FIG. 11 is a schematic illustration of a papermaking machine having a wet-end section, a press section, and a dryer section;

FIG. 12 is a side elevational view of a vibrational device according to an embodiment of the present invention, positioned within the press section of a papermaking machine;

FIG. 13 is a schematic representation of a felt for use in the press section of a papermaking machine;

FIGS. 14a and 14b are cross-sectional views of a vibrational device having dampening mechanisms according to another embodiment of the present invention;

FIG. 15 is a front elevational view of a vibrational device having a single vibrational element mounted to multiple support members according to another embodiment of the present invention; and

FIG. 16 is an exploded perspective view of the vibrational device of FIGS. 14a and 14b.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, a preferred embodiment of the present invention employs a papermaking machine wet-end section 10 and a vibrational device 100. The papermaking machine wet-end section 10 can precede the press and dryer sections in a conventional papermaking machine. The papermaking machine wet-end section 10 as shown in FIG. 1 is also referred to as the forming section or the Fourdrinier table of the papermaking machine. The papermaking machine wet-end section 10 preferably includes a papermaking machine frame 12, a headbox 14, a wire 16, a breast roll 22, a couch roll 24, a plurality of return rolls 26, and a plurality of suction devices 28.

The headbox 14 is positioned adjacent to the papermaking machine frame 12 in order to distribute stock flow onto the wire 16. Any conventional headbox in the papermaking art can be employed in order to distribute stock flow onto the wire 16. The headbox 14 preferably distributes stock flow to the wire 16 in order to produce a web having uniform properties across the width of the wire 16, referred to as the cross-machine direction (CD), along the length of the wire 16, referred to as the machine direction (MD), and through the cross-section of the web, referred to as the Z direction (Z), as shown in FIG. 1. As best shown in FIG. 4, the headbox 14 preferably distributes stock flow to the wire 16 at an angle of impingement .alpha., which is an angle other than absolute tangent to the wire 16. The angle of impingement .alpha. is the angle between two portions of the headbox 14, namely an apron lip 15 and a slice lip 17. If the angle of impingement .alpha. is steep, i.e., close to absolute tangent to the wire 16, the arrangement of the headbox is referred to as pressure forming. If the angle of impingement .alpha. is shallow, i.e., not close to absolute tangent, the arrangement of the headbox 14 is referred to as velocity forming.

The wire 16, which may also be referred to as the Fourdrinier wire, is preferably a moving, endless belt of wire-mesh screen. The wire 16 is movably coupled to the papermaking machine frame 12 via several rolls in a manner that provides an endless conveyor belt for receiving and transporting stock flow distributed by the headbox 14. The wire 16 first wraps around the breast roll 22, (which is preferably positioned adjacent to the headbox 14 and generally directly under the headbox 14), stretches from the breast roll 22 across the length of the wet-end section 10 to the couch roll 24, wraps around the couch roll 24, and stretches around the plurality of return rolls 26 to return to the breast roll 22. One having ordinary skill in the art will appreciate that the wire 16 can be driven about other elements in an endless-conveyor arrangement, such as by being passed around one or more sprockets, pulleys, or other preferably rotatable elements.

As shown in FIG. 3, the wire 16 is preferably a delicate, finely woven metal or synthetic fiber cloth that allows the drainage of water, but retains most of the fibers from the stock flow. Although finely woven metal or synthetic fiber wire is preferred, any other type of papermaking wire can be employed in connection with the present invention. In one highly preferred type of wire shown in FIG. 3, a plurality of main strands 18 and a plurality of connecting strands 20 are woven together to form the wire 16. The plurality of main strands 18 and the plurality of connecting strands 20 can be made of finely drawn and woven, annealed bronze or brass, or can be made of other conventional wire materials as desired. For example, the plurality of main strands 18 and the plurality of connecting strands 20 can instead be made of polyester monofilaments. The weave of the wire 16 can be varied in order to inhibit or aid drainage through the wire 16. One of ordinary skill in the art will appreciate that the weave pattern of the wire 16 can be of single, double, triple, or any other layer design and therefore needs no further description herein. The wire 16 is preferably not a permanent part of the papermaking machine wet-end section 10 and can be replaced in a conventional manner.

As shown in FIGS. 1 and 2, a plurality of devices 28 are preferably employed to control water within and exiting from the stock flow, leaving a wet sheet of matted pulp, i.e. the web, that travels on the wire 16. In the highly preferred embodiment shown in FIGS. 1 and 2, these devices 28 include an initial forming board 30, a plurality of foil boxes 32, and at least one vibrational device 100. The initial forming board 30 is preferably an elongated board having a flat topside positioned under the wire 16. Alternative types of initial forming boards can instead be used as desired. Preferably, the initial forming board 30 is positioned downstream from the headbox 14 so that it is the first of the devices 28 to engage the wire 16. In this position, the initial forming board 30 creates an initial dwell time during which a small amount of water is drained from the stock flow and the web is allowed to begin forming as the wire 16 travels over the initial forming board 30. The initial forming board 30, and forming boards in general, are well-known devices in the papermaking art and are not therefore described further herein.

The plurality of foil boxes 32 are preferably positioned under the wire 16, downstream from the initial forming board 30, and run in the cross-machine direction. Preferably, each one of the plurality of foil boxes 32 is coupled to the papermaking machine frame 12 and includes a plurality of T-bars 34 and a plurality of stationary (or adjustable) foils or blades 36 coupled to the plurality of T-bars 34. As is conventional in the papermaking industry, the stationary foils 36 are each preferably 21/2 inches wide. However, the stationary foils 36 may be any width. The stationary foils 36 each preferably have a lead angle that strips water off of the wire and a surface downstream from the lead angle that creates a vacuum to pull water down from the wire 16. The surface downstream from the lead angle is preferably flat, but can be shaped in a number of different manners to generate vacuum downstream of the lead angle (including without surfaces that are wave-shaped, stepped, multi-faceted, curved convexly and/or concavely, and the like). The lead angle of each subsequent, downstream stationary foil 36 strips the water off of the wire 16 that was pulled down by the vacuum created by the preferably flat surface of the preceding, upstream stationary foil 36. In this manner, water is drained from the wire 16 in the wet-end section 10 and the web begins to form. The wet-end section 10 can include a large number (e.g., 100) of stationary foils 36 coupled to the plurality of foil boxes 32. It should be noted that stationary foils 36 need not necessarily be connected to or otherwise be used in conjunction with foil boxes 32, although foil boxes 32 are a preferred manner of collecting and transporting water from beneath the wire 16. In addition, although T-shaped bars 34 are a highly preferred manner of connecting the stationary foils 36 to associated framework of the papermaking machine, the stationary foils 36 can be connected in desired locations in any other conventional manner, such as by fastening the stationary foils 34 with one or more bolts, screws, clamps, rivets, pins, or other conventional fasteners, by snap-fitting the foils to connecting points on the papermaking machine, and the like. Stationary foils, their manner of operation and connection, and the various forms of stationary foils are also well-known suction devices in the papermaking art and are not therefore described further herein.

The papermaking machine wet-end section 10 preferably also includes at least one vibrational device 100. As shown in FIGS. 5a and 5b, the vibrational device 100 includes a vibrational device frame 102 mountable to the papermaking machine frame 12 (or to other positions inside or adjacent to the papermaking machine frame 12), one or more vibration-inducing mechanisms 104 coupled to the vibrational device frame 102, a vibrational head 106 coupled to the vibration-inducing mechanisms 104, and one or more vibration isolators 105 coupled between the vibrational head 106 and the vibrational device frame 102. The vibrational device frame 102 preferably includes a truss network 108 which provides a bridge between each side of the papermaking machine frame 12 for supporting the vibrational device 100 under the wire 16. The truss network 108 includes a horizontal truss 110, a pair of diagonal trusses 112a and 112b coupled to each end of the horizontal truss 110, and a pair of brackets 114a and 114b coupled to the ends of the diagonal trusses 112a and 112b. Preferably, the horizontal truss 110 is mounted under the wire 16 and runs in substantially the cross-machine direction. Preferably, the horizontal truss 110 spans the entire width of the wire 16.

The diagonal truss 112a is coupled between a first end 116a of the horizontal truss 110 and the bracket 114a. The diagonal truss 112b is coupled between a second end 116b of the horizontal truss 110 and the bracket 114b. Rather than using a single horizontal truss to support the vibrational device 100, the pair of diagonal trusses 112a and 112b are preferably used to position the horizontal truss 110 somewhat below the height of the papermaking machine frame 12. However, a single horizontal truss could be used to support the vibrational device 100.

In other preferred embodiments as shown in FIGS. 5b and 5c, a vibrational device 200 includes a truss network 208. The truss network 208 includes a first horizontal truss 210, a vertical truss 212, a second horizontal truss 214, and a diagonal support truss 216. The first horizontal truss 210 is coupled to a first end 218 of the vertical truss 212, and the second horizontal truss 214 is coupled to a second end 220 of the vertical truss 212. The diagonal support truss 216 is coupled between the second horizontal truss 214 and the vertical truss 212. The embodiment of the present invention in FIG. 5c is an example of how the trusses, truss ends, and vertical adjustment mechanisms (described in greater detail below) of the various embodiments of the present invention can be interchanged as desired.

Still other truss network shapes and designs are possible for serving the purpose of supporting the vibrational devices 100, 200 adjacent to the wire 16, each one of which falls within the spirit and scope of the present invention. Specifically, any truss element or structure having any shape and being made from any number of elements (including without limitation plates, beams, rods, bars, and the like) connected together in any conventional manner could be used to support the vibrational device 100, 200 from beneath as shown in the figures or from any other location on the vibrational device 100, 200. The resulting truss element or structure can have any shape desired, and can be connected to the papermaking machine frame in any conventional manner (i.e., with or without brackets). Most preferably however, the truss element or structure provides substantially no vertical deflection in the center of the cross-machine direction of the wire 16. Put differently, the truss network preferably provides a mounting base for the vibrational device 100, 200 that runs in the cross-machine direction and is completely stationary with respect to the vertical orientation of the wire 16.

Although the vibrational device 100, 200 is preferably connected to and supported by the horizontal truss 110, 210 as described above, it should be noted that in some alternative embodiments the vibrational device 100, 200 is connected directly to a member of the papermaking machine frame (e.g., a beam, plate, stretcher, or other element running partially or fully across the papermaking machine in the cross-machine direction). This papermaking machine frame member can be rigidly and permanently attached to the remainder of the papermaking machine or can be adjustable as described in more detail below with regard to the horizontal truss 110, 210 in the illustrated preferred embodiments.

With particular reference to FIG. 6a, each bracket 114a, 114b in the illustrated preferred embodiment of FIGS. 4 and 5a preferably has a bottom plate 117 and a top plate 118 coupled between a vertical adjustment mechanism 120. As shown in FIG. 5a, the bottom plate 117 preferably includes a horizontal engagement surface 122 and a pair of diagonal engagement surfaces 124a and 124b. The diagonal engagement surfaces 124a and 124b are preferably configured to form a narr