CA2206023A1 - Method and headbox for a paper machine - Google Patents
Method and headbox for a paper machineInfo
- Publication number
- CA2206023A1 CA2206023A1 CA002206023A CA2206023A CA2206023A1 CA 2206023 A1 CA2206023 A1 CA 2206023A1 CA 002206023 A CA002206023 A CA 002206023A CA 2206023 A CA2206023 A CA 2206023A CA 2206023 A1 CA2206023 A1 CA 2206023A1
- Authority
- CA
- Canada
- Prior art keywords
- flow
- headbox
- elements
- chamber
- flow chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/02—Head boxes of Fourdrinier machines
- D21F1/026—Details of the turbulence section
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/02—Head boxes of Fourdrinier machines
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/02—Head boxes of Fourdrinier machines
- D21F1/028—Details of the nozzle section
Abstract
A headbox for a paper machine has a flow chamber through which the pulp suspension flows and an outlet slot through which the suspension exits. For controlling turbulence and flow in the flow chamber, a plurality of flow elements are disposed in the flow chamber in the suspension path. The flow elements are individually adjustable in size in the chamber, e.g., by moving into and out of respective pockets, during operation. The flow elements may comprise plates extending across the width of the slot or rods arranged in one or more rows across the width of the slot. The flow elements either do not extend through or extend through the outlet slot. During operation of the flow elements, they do not affect the width or height of the outlet slot.
Description
CA 02206023 1997-0~-23 ~ .
METHOD AND HEADBOX FOR A PAPER MACHINE
BACKGROUND OF THE INVENTION
The present invention relates to a method and a headbox for a paper machine. In particular, the invention concerns a headbox with inserts for producing or controlling turbulence in the flow of pulp suspension through the headbox.
Relevant prior art documents are:
(1) US 3,769,155 (2) US 3,514,372 (3) DE 43 21 697 (4) DE 32 27 218 Al (S) US 3,843,470 (6) DE 44 02 625 Al These documents disclose elements within the flow chamber of the headbox that influence the fluid hydraulics. Such elements can, for instance, comprise separate blades in the case of multi-layer headboxes.
Their influence on the fluid hydraulics is due primarily to the fluid friction. Particularly, the degree of turbulence in the flow is affected by the elements. This is of great importance for forming the sheet or web of paper.
~ Document (5) describes a headbox in which the upstream ends of the flow elements do not extend up into the region of the outlet slot. Document (6) describes a headbox in which the surfaces of the flow elements are variable in their positions in the headbox.
Known headboxes which have elements in the flow chamber for controlling turbulence have a serious SPEC~323 CA 02206023 1997-0~-23 disadvantage. Control of the conditions of flow, and particularly the turbulence, is not possible during operation. Each headbox has very specific characteristics which cannot be changed. This is disadvantageous since numerous operating parameters are subject to continuous change during operation, for instance, the composition of the pulp, the temperature, and the velocity of flow.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for use of a headbox and a headbox wherein the hydraulics of the pulp slurry, and particularly the degree of turbulence, can be controlled in a variable manner during operation.
According to the invention, the surfaces of the flow elements in the flow chamber which are contacted by the pulp suspension or slurry are variable during operation of the headbox. On the other hand, the downstream ends of those flow elements have no effect on the height above the wire or the width across the wire of the outlet slot of the headbox. A headbox for a paper machine has a flow chamber through which the pulp suspension flows and an outlet slot through which the suspension exits. For controlling turbulence and flow in the flow chamber, a plurality of flow elements are disposed in the flow chamber along the suspension path.
The flow elements are adjustable in their respective sizes in the chamber, e.g., by moving into and out of respective pockets, during operation. The flow elements may comprise plates extending across the width of the slot or rods arranged in one or more rows across the width of the slot and each flow element is individually SPEC~323 CA 02206023 1997-0~-23 .
controllable. The flow elements either do not extend through or extend through the outlet slot. Regardless of that dimension, during operation of the flow elements, they do not affect the width or height of the outlet slot.
The inventors have discovered that changing the size of the flow contacted surfaces by itself has a very considerable effect on the flow hydraulics. Thus, one may change not only the shape of inserts present in the flow chamber to have such effect, but also their respectlve sizes.
Document (4) discloses a multi-layer headbox having a nozzle-like outlet channel which is divided into three individual channels. The individual channels are separated from each other by tongues which are , .
displaceable in the direction of flow. Displacement of these tongues, however, does not increase the flow contacted surfaces of the tongues, but instead adjusts the width of the outlet slot of the individual channels.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic side view of a headbox for a paper machine;
Fig. 2 schematically shows the outlet nozzle of the headbox, also in side view, with flow elements in accordance with the invention;
Fig. 3 is a top view of the outlet nozzle of Fig. 2;
SPEC~323 CA 02206023 1997-0~-23 .
Fig. 4 schematically shows another embodiment of the invention, in a view similar to that of Fig. 2;
Fig. 5 schematically shows a multi-layer headbox in side view; and Fig. 6 schematically shows a three-layer headbox in side view.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTICN
The headbox shown in Fig. 1 comprises a flow chamber 1. The chamber has an inlet 2 at one side of the headbox. An outlet nozzle 3 is arranged at another side of the headbox following the flow chamber 1 in the path of flow through the headbox. The outlet nozzle dispenses liquid pulp suspension or slurry onto a conventional forming section wire screen (not shown) that moves beneath the nozzle and receives suspension from the nozzle outlet.
The flow chamber 1 contains a bundle comprised of a plurality of tubes 1.1 which are arrayed vertically in rows, as shown in Fig. 2, which rows are also arrayed across the headbox mapping a multi-tube matrix across the headbox. The tubes extend in the direction of flow.
They serve, in known manner, to produce microturbulence in the pulp slurry.
Figs. 2 and 3 detail the outlet nozzle 3 having the flow elements in accordance with the invention. Fig.
2 shows the outlet nozzle 3 having two external bottom and top limiting walls 3.1 and 3.2 which taper toward each other to form an outlet slot 3.3 with each other at their downstream ends. Figs. 2 and 3 show pockets located in the flow chamber in which flow elements in accordance with the invention are mounted. Fig. 2 shows three rows of pockets with their corresponding flow SPEC~323 CA 02206023 1997-0~-23 elements and arranged one row above the other. These include a top row of separated pockets 3.4, each with a corresponding flow element 3.41, a middle row of pockets 3.5, each with a corresponding flow element 3.51, and a bottom row of pockets 3.6, each with a corresponding flow element 3.61. The flow elements are illustrated as round rods. Any other cross-sectional shape may be employed, e.g., oval, rectangular. They are movable in and out of their respective pockets in the direction of suspension flow, as indicated by the double-ended arrow in Fig. 3.
Inward and outward movement of any flow element 3.41, 3.51, and 3.61 changes the respective size of its flow contacted surfaces. This influences the flow hydraulics. Figs 2 and 3 show a total of twelve round rods and their corresponding pockets. All or some of the round rods in each single row of round rods can be moved in or out to a respective different extent. However, all round rods of all lines can also be moved out to different extents. The flow is influenced in accordance with the extent to which the individual round rods are moved out.
Although each of the rods is illustrated as a solid rod, at least some if not all of the rods may be hollow, and their hollows may be connected by appropriate conduits to a source of vacuum or pressure. Such rods are open, e.g., at their free ends, into the flow chamber, and the suction at their openings also affects turbulence of the suspension.
The embodiment in Fig. 4 shows an outlet nozzle 3 of an entirely different shape. The pulp slurry is conducted by a plurality of channels 5.1, 5.2, 5.3 to the outlet slot 3.3. The channels are drilled through respective solid blocks 6.1, 6.2, 6.3. The limiting SPEC\2~323 CA 02206023 1997-0~-23 walls 3.1, 3.2 are in the downstream end region of the outlet nozzle 3 and are fixed.
Flow elements 3.71 and 3.81 in accordance with the invention are provided. These flow elements are of plate shape, rather than rod shape. Each plate element extends over the entire working width of the headbox.
The elements are again mounted in respective pockets 3.7 and 3.8 defined in the interfaces between neighboring blocks 6.1, 6.2, 6.3. In the same manner as the round rods of Figs. 2 and 3, the flow elements can also be moved along the direction of flow, so that the sizes of the flow contacted surfaces of these flow elements 3.71, 3.81 can be changed.
As can be seen, the plate shaped flow elements 3.71 and 3.81 can in the present case be moved out to extend beyond the outlet slot 3.3.
In a particularly interesting embodiment, the flow elements, i.e., rods or plates, have surface regions of different roughness along the direction of their displacement. For instance, a downstream part can be have a particularly small degree of roughness while the roughness increases in the upstream direction. The effect of moving out individual flow elements is thereby progressively increased. This enhances the effect upon turbulence of the suspension.
In the embodiment shown in Fig. 5, the turbulence producing element 3.41 extends beyond the outlet slots 3.31 and 3.32 defined by the walls 3.1 and 3.2. The flow element 3.41 produces additional turbulence due to its boundary-layer friction with the fiber slurry or pulp suspension (not shown) which has already emerged from the nozzle 3. As long as the tip of the flow element 3.41 is not withdrawn behind the slots SPEC\200323 CA 02206023 1997-0~-23 3.31 and 3.32, the widths of the outlet slots 3.31 and 3.41 remain constant. This same is also true when the flow elements move only inside the nozzle. In this way, the degree of turbulence in the slurry or suspension can be adjusted without thereby changing the amount of slurry which flows out.
Fig. 6 shows a variant of Fig. 5. Instead of there being only one flow element, two flow elements are present. (However, still further flow elements are possible). Within the nozzle 3 the courses of the flow elements 3.41 and 3.51 are arranged to be converging in the direction of flow for reasons of fluid mechanics.
In order that the heights (above the wire) of the three outlet slots 3.31, 3.32 and 3.33 not change upon displacement of the flow elements 3.41 and 3.51, it is necessary for the flow elements 3.41 and 3.51 to be of resilient material and to extend parallel to each other where they pass through the outlet openings. This parallel alignment is produced by specific control of the pressures of the individual streams in the nozzle 3 and by dimensioning of the bending stress in the flow elements 3.41 and 3.51.
It is obvious that the flow elements in Figs. 5 and 6 can be either flat as in Fig. 4 or of rod shape as in Fig. 2.
Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be - limited not by the specific disclosure herein, but only by the appended claims.
SPEC\~323
METHOD AND HEADBOX FOR A PAPER MACHINE
BACKGROUND OF THE INVENTION
The present invention relates to a method and a headbox for a paper machine. In particular, the invention concerns a headbox with inserts for producing or controlling turbulence in the flow of pulp suspension through the headbox.
Relevant prior art documents are:
(1) US 3,769,155 (2) US 3,514,372 (3) DE 43 21 697 (4) DE 32 27 218 Al (S) US 3,843,470 (6) DE 44 02 625 Al These documents disclose elements within the flow chamber of the headbox that influence the fluid hydraulics. Such elements can, for instance, comprise separate blades in the case of multi-layer headboxes.
Their influence on the fluid hydraulics is due primarily to the fluid friction. Particularly, the degree of turbulence in the flow is affected by the elements. This is of great importance for forming the sheet or web of paper.
~ Document (5) describes a headbox in which the upstream ends of the flow elements do not extend up into the region of the outlet slot. Document (6) describes a headbox in which the surfaces of the flow elements are variable in their positions in the headbox.
Known headboxes which have elements in the flow chamber for controlling turbulence have a serious SPEC~323 CA 02206023 1997-0~-23 disadvantage. Control of the conditions of flow, and particularly the turbulence, is not possible during operation. Each headbox has very specific characteristics which cannot be changed. This is disadvantageous since numerous operating parameters are subject to continuous change during operation, for instance, the composition of the pulp, the temperature, and the velocity of flow.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for use of a headbox and a headbox wherein the hydraulics of the pulp slurry, and particularly the degree of turbulence, can be controlled in a variable manner during operation.
According to the invention, the surfaces of the flow elements in the flow chamber which are contacted by the pulp suspension or slurry are variable during operation of the headbox. On the other hand, the downstream ends of those flow elements have no effect on the height above the wire or the width across the wire of the outlet slot of the headbox. A headbox for a paper machine has a flow chamber through which the pulp suspension flows and an outlet slot through which the suspension exits. For controlling turbulence and flow in the flow chamber, a plurality of flow elements are disposed in the flow chamber along the suspension path.
The flow elements are adjustable in their respective sizes in the chamber, e.g., by moving into and out of respective pockets, during operation. The flow elements may comprise plates extending across the width of the slot or rods arranged in one or more rows across the width of the slot and each flow element is individually SPEC~323 CA 02206023 1997-0~-23 .
controllable. The flow elements either do not extend through or extend through the outlet slot. Regardless of that dimension, during operation of the flow elements, they do not affect the width or height of the outlet slot.
The inventors have discovered that changing the size of the flow contacted surfaces by itself has a very considerable effect on the flow hydraulics. Thus, one may change not only the shape of inserts present in the flow chamber to have such effect, but also their respectlve sizes.
Document (4) discloses a multi-layer headbox having a nozzle-like outlet channel which is divided into three individual channels. The individual channels are separated from each other by tongues which are , .
displaceable in the direction of flow. Displacement of these tongues, however, does not increase the flow contacted surfaces of the tongues, but instead adjusts the width of the outlet slot of the individual channels.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic side view of a headbox for a paper machine;
Fig. 2 schematically shows the outlet nozzle of the headbox, also in side view, with flow elements in accordance with the invention;
Fig. 3 is a top view of the outlet nozzle of Fig. 2;
SPEC~323 CA 02206023 1997-0~-23 .
Fig. 4 schematically shows another embodiment of the invention, in a view similar to that of Fig. 2;
Fig. 5 schematically shows a multi-layer headbox in side view; and Fig. 6 schematically shows a three-layer headbox in side view.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTICN
The headbox shown in Fig. 1 comprises a flow chamber 1. The chamber has an inlet 2 at one side of the headbox. An outlet nozzle 3 is arranged at another side of the headbox following the flow chamber 1 in the path of flow through the headbox. The outlet nozzle dispenses liquid pulp suspension or slurry onto a conventional forming section wire screen (not shown) that moves beneath the nozzle and receives suspension from the nozzle outlet.
The flow chamber 1 contains a bundle comprised of a plurality of tubes 1.1 which are arrayed vertically in rows, as shown in Fig. 2, which rows are also arrayed across the headbox mapping a multi-tube matrix across the headbox. The tubes extend in the direction of flow.
They serve, in known manner, to produce microturbulence in the pulp slurry.
Figs. 2 and 3 detail the outlet nozzle 3 having the flow elements in accordance with the invention. Fig.
2 shows the outlet nozzle 3 having two external bottom and top limiting walls 3.1 and 3.2 which taper toward each other to form an outlet slot 3.3 with each other at their downstream ends. Figs. 2 and 3 show pockets located in the flow chamber in which flow elements in accordance with the invention are mounted. Fig. 2 shows three rows of pockets with their corresponding flow SPEC~323 CA 02206023 1997-0~-23 elements and arranged one row above the other. These include a top row of separated pockets 3.4, each with a corresponding flow element 3.41, a middle row of pockets 3.5, each with a corresponding flow element 3.51, and a bottom row of pockets 3.6, each with a corresponding flow element 3.61. The flow elements are illustrated as round rods. Any other cross-sectional shape may be employed, e.g., oval, rectangular. They are movable in and out of their respective pockets in the direction of suspension flow, as indicated by the double-ended arrow in Fig. 3.
Inward and outward movement of any flow element 3.41, 3.51, and 3.61 changes the respective size of its flow contacted surfaces. This influences the flow hydraulics. Figs 2 and 3 show a total of twelve round rods and their corresponding pockets. All or some of the round rods in each single row of round rods can be moved in or out to a respective different extent. However, all round rods of all lines can also be moved out to different extents. The flow is influenced in accordance with the extent to which the individual round rods are moved out.
Although each of the rods is illustrated as a solid rod, at least some if not all of the rods may be hollow, and their hollows may be connected by appropriate conduits to a source of vacuum or pressure. Such rods are open, e.g., at their free ends, into the flow chamber, and the suction at their openings also affects turbulence of the suspension.
The embodiment in Fig. 4 shows an outlet nozzle 3 of an entirely different shape. The pulp slurry is conducted by a plurality of channels 5.1, 5.2, 5.3 to the outlet slot 3.3. The channels are drilled through respective solid blocks 6.1, 6.2, 6.3. The limiting SPEC\2~323 CA 02206023 1997-0~-23 walls 3.1, 3.2 are in the downstream end region of the outlet nozzle 3 and are fixed.
Flow elements 3.71 and 3.81 in accordance with the invention are provided. These flow elements are of plate shape, rather than rod shape. Each plate element extends over the entire working width of the headbox.
The elements are again mounted in respective pockets 3.7 and 3.8 defined in the interfaces between neighboring blocks 6.1, 6.2, 6.3. In the same manner as the round rods of Figs. 2 and 3, the flow elements can also be moved along the direction of flow, so that the sizes of the flow contacted surfaces of these flow elements 3.71, 3.81 can be changed.
As can be seen, the plate shaped flow elements 3.71 and 3.81 can in the present case be moved out to extend beyond the outlet slot 3.3.
In a particularly interesting embodiment, the flow elements, i.e., rods or plates, have surface regions of different roughness along the direction of their displacement. For instance, a downstream part can be have a particularly small degree of roughness while the roughness increases in the upstream direction. The effect of moving out individual flow elements is thereby progressively increased. This enhances the effect upon turbulence of the suspension.
In the embodiment shown in Fig. 5, the turbulence producing element 3.41 extends beyond the outlet slots 3.31 and 3.32 defined by the walls 3.1 and 3.2. The flow element 3.41 produces additional turbulence due to its boundary-layer friction with the fiber slurry or pulp suspension (not shown) which has already emerged from the nozzle 3. As long as the tip of the flow element 3.41 is not withdrawn behind the slots SPEC\200323 CA 02206023 1997-0~-23 3.31 and 3.32, the widths of the outlet slots 3.31 and 3.41 remain constant. This same is also true when the flow elements move only inside the nozzle. In this way, the degree of turbulence in the slurry or suspension can be adjusted without thereby changing the amount of slurry which flows out.
Fig. 6 shows a variant of Fig. 5. Instead of there being only one flow element, two flow elements are present. (However, still further flow elements are possible). Within the nozzle 3 the courses of the flow elements 3.41 and 3.51 are arranged to be converging in the direction of flow for reasons of fluid mechanics.
In order that the heights (above the wire) of the three outlet slots 3.31, 3.32 and 3.33 not change upon displacement of the flow elements 3.41 and 3.51, it is necessary for the flow elements 3.41 and 3.51 to be of resilient material and to extend parallel to each other where they pass through the outlet openings. This parallel alignment is produced by specific control of the pressures of the individual streams in the nozzle 3 and by dimensioning of the bending stress in the flow elements 3.41 and 3.51.
It is obvious that the flow elements in Figs. 5 and 6 can be either flat as in Fig. 4 or of rod shape as in Fig. 2.
Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be - limited not by the specific disclosure herein, but only by the appended claims.
SPEC\~323
Claims (30)
1. A headbox for a paper machine comprising walls defining a flow chamber for pulp suspension, wherein the chamber is at least approximately equal to the working width of a paper machine wire with which the headbox cooperates;
an inlet to the flow chamber for pulp suspension;
the headbox having walls which are shaped for defining an outlet nozzle from the flow chamber, including an outlet slot extending across the width of the headbox and through which the pulp suspension exits the flow chamber and the headbox;
flow elements supported in the flow chamber and also in the path of flow of suspension through the flow chamber and past the flow elements; the flow elements being adjustable in size within the flow of suspension for increasing or reducing the size of the flow elements contacted by the pulp suspension during passage of the pulp suspension at least through the flow chamber.
an inlet to the flow chamber for pulp suspension;
the headbox having walls which are shaped for defining an outlet nozzle from the flow chamber, including an outlet slot extending across the width of the headbox and through which the pulp suspension exits the flow chamber and the headbox;
flow elements supported in the flow chamber and also in the path of flow of suspension through the flow chamber and past the flow elements; the flow elements being adjustable in size within the flow of suspension for increasing or reducing the size of the flow elements contacted by the pulp suspension during passage of the pulp suspension at least through the flow chamber.
2. The headbox of claim 1, wherein the flow elements are adjustable in size to also be contacted by the pulp suspension outside the flow chamber past the outlet slot.
3. The headbox of claim 1, wherein the flow elements are located in the flow chamber spaced inwardly from the walls defining the flow chamber.
4. The headbox of claim 1, further comprising means supporting the flow elements in the flow chamber for moving with respect to the flow chamber selectively in one direction with reference to the flow path of the pulp suspension through the flow chamber for increasing the size of the flow elements in the flow chamber or in the opposite direction for decreasing the size of the flow elements in the flow chamber.
5. The headbox of claim 1, further comprising a respective pocket in the headbox for supporting each flow element and each flow element is selectively movable into and out of the pocket for respectively decreasing or increasing the size of the flow element in the flow chamber.
6. The headbox of claim 5, wherein the flow elements are so oriented in the respective pockets and are so moved that the parts of the flow elements that move outward of the respective pockets extend in the direction of flow of pulp suspension through the flow chamber.
7. The headbox of claim 6, wherein the flow elements extending in the direction of flow of the pulp suspension include downstream ends with respect to the direction of flow of pulp suspension, the downstream ends being so positioned in the headbox as to avoid having effect on the height of the outlet slot from the flow chamber regardless of the amount which the flow elements are moved out of the respective pockets therefor and along the direction of flow of the suspension.
8. The headbox of claim 7, wherein the pockets are so placed and the flow elements are of such length and are so movable that their movement into and out of the pockets and along the direction of flow is entirely contained within the flow chamber and upstream of the outlet slot with respect to the path of flow of suspension to the outlet slot.
9. The headbox of claim 7, wherein the outlet slot defined by the walls of the flow chamber has an opening of a particular height above the wire; the flow elements being of such length and the pockets thereof being so placed that the downstream ends of the flow elements project out of and beyond the outlet slot; the flow elements being so shaped and being so supported in their respective pockets that where they pass through the outlet slots, the flow elements remain uniformly spaced from the flow chamber walls at the outlet slot so that the flow elements passing through the outlet slot are without effect on the height of the outlet slot during the movement of the flow elements into and out of the pockets therefor.
10. The headbox of claim 7, wherein the outlet slot has a height above the wire which does not vary during operation of the headbox, even as the flow elements are moved with reference to the flow chamber.
11. The headbox of claim 6, wherein there are a plurality of the flow elements and each of the flow elements comprises a plate in the flow chamber having a width across the flow chamber which extends at least over a part of the working width of the flow chamber and the paper machine wire.
12. The headbox of claim 11, wherein there are a plurality of the plates, with one plate arranged above the other over the height of the flow chamber above the wire, the plates being spaced apart in the height direction and each of the plates being individually movable for adjusting the respective size thereof in the flow chamber.
13. The headbox of claim 6, wherein each of the flow elements comprises a rod and each of the pockets comprises a respective recess into and out of which the rod is lengthwise shiftable.
14. The headbox of claim 13, wherein the flow element rods are arranged in at least one row extending in the direction of the width of the flow chamber and the paper machine wire, the respective pockets for the rods being arranged in a row and respective rods being arranged spaced apart from each other across the width of the flow chamber.
15. The headbox of claim 14, wherein there are a plurality of the rows of the flow element rods over the height of the flow chamber, and the rods being individually movable into and out of the respective pockets therefor for individually adjusting the size of each rod.
16. The headbox of claim 6, wherein the flow elements are flexible.
17. The headbox of claim 16, wherein the pockets for the flow elements are oriented obliquely to the outlet slot and extend generally toward the outlet slot, while the flow elements movable into and out of the pockets are respectively so shaped as to not change the width of the outlet slot or the height thereof in the direction above the wire as the flow elements move into and out of the pockets.
18. The headbox of claim 6, wherein the pockets for the flow elements are oriented obliquely to the outlet slot and extend generally toward the outlet slot, while the flow elements movable into and out of the pockets are respectively so shaped as to not change the width of the outlet slot and the height thereof in the direction above the wire as the flow elements move into and out of the pockets.
19. The headbox of claim 6, wherein the flow elements are rigid and inflexible.
20. The headbox of claim 6, wherein the flow elements include side surfaces which are contacted by the suspension flowing through the headbox and as seen in the direction of flow, the flow elements having zones of different roughness for enhancing the effect of the flow elements on the pulp suspension flowing therepast.
21. The headbox of claim 6, wherein the flow elements project out of the respective pockets therefor in the flow chamber a distance in the range of 10 to 300 nm.
22. The headbox of claim 6, wherein the flow elements project out of the respective pockets therefor in the flow chamber a distance in the range of 50 to 200 nm.
23. The headbox of claim 6, wherein each of the flow elements is hollow and the hollow spaces of the flow elements are connected to a vacuum source.
24. The headbox of claim 6, further comprising a plurality of tubes assembled into a matrix in the flow chamber upstream of the flow elements and extending in the flow direction and the pulp suspension passes through the tubes and then passes to the flow elements, the tubes creating micro turbulence in the pulp suspension before the pulp suspension reaches the flow elements.
25. A headbox for a paper machine comprising walls defining a flow chamber for pulp suspension, wherein the chamber is at least approximately equal to the working width of a paper machine wire with which the headbox cooperates;
an inlet to the flow chamber for pulp suspension;
the headbox having walls which are shaped for defining an outlet nozzle from the flow chamber, including an outlet slot extending across the width of the headbox and through which the pulp suspension exits the flow chamber and the headbox;
flow elements supported in the flow chamber and also in the path of flow of suspension through the flow chamber and past the flow elements; the flow elements being adjustable within the flow of suspension for selectively increasing or decreasing the surface of each flow element contacted by the pulp suspension during passage of the pulp suspension at least through the flow chamber.
an inlet to the flow chamber for pulp suspension;
the headbox having walls which are shaped for defining an outlet nozzle from the flow chamber, including an outlet slot extending across the width of the headbox and through which the pulp suspension exits the flow chamber and the headbox;
flow elements supported in the flow chamber and also in the path of flow of suspension through the flow chamber and past the flow elements; the flow elements being adjustable within the flow of suspension for selectively increasing or decreasing the surface of each flow element contacted by the pulp suspension during passage of the pulp suspension at least through the flow chamber.
26. A method of controlling the flow of pulp suspension through a flow chamber of a headbox of a paper machine, wherein the flow chamber has a plurality of flow elements disposed therein which are adjustable in their size in the flow chamber, the method comprising:
varying the degree of turbulence in the suspension passing through the flow chamber by selectively displacing or not displacing each of the flow elements to a respective extent to alter the effective sizes of the displaced flow elements in the flow chamber during operation of the headbox.
varying the degree of turbulence in the suspension passing through the flow chamber by selectively displacing or not displacing each of the flow elements to a respective extent to alter the effective sizes of the displaced flow elements in the flow chamber during operation of the headbox.
27. The method of claim 26, wherein the headbox has an outlet slot through which the pulp suspension exits the headbox and the flow elements are so placed in the flow chamber and are so displaced in the flow chamber during operation of the headbox that as the sizes of the flow elements are altered, the flow elements do not affect the height or width of the outlet slot.
28. The method of claim 27, wherein the flow elements are displaced by moving them into and out of respective pockets therefor in the flow chamber.
29. The method of claim 27, wherein the flow elements are displaced in the flow chamber always upstream of the outlet slot from the flow chamber.
30. The method of claim 26, wherein the flow elements normally project from inside the flow chamber through the outlet slot from the flow chamber and the flow elements are so shaped and are displaceable as to maintain the height of the outlet slot and the spacing between the flow elements passing through the outlet slot constant during operation of the headbox and displacement of the flow elements.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19621258.8 | 1996-05-25 | ||
| DE19621258A DE19621258C1 (en) | 1996-05-25 | 1996-05-25 | Papermaking machine stock inlet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2206023A1 true CA2206023A1 (en) | 1997-11-25 |
Family
ID=7795408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002206023A Abandoned CA2206023A1 (en) | 1996-05-25 | 1997-05-23 | Method and headbox for a paper machine |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0812951B1 (en) |
| CA (1) | CA2206023A1 (en) |
| DE (2) | DE19621258C1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19908973A1 (en) * | 1999-03-02 | 2000-09-07 | Voith Sulzer Papiertech Patent | Process for regulating the tear length ratio of a paper web and paper machine produced |
| DE10324711A1 (en) * | 2003-05-30 | 2004-12-30 | Voith Paper Patent Gmbh | headbox |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3514372A (en) * | 1966-11-29 | 1970-05-26 | Beloit Corp | Headbox method and means for blending of multiple jets |
| AT305754B (en) * | 1970-02-18 | 1973-03-12 | Voith Gmbh J M | Headbox for paper machines |
| US3843470A (en) * | 1970-08-31 | 1974-10-22 | Beloit Corp | Flexible trailing elements in a paper-making machine headbox having projections thereon extending into the slurry flow |
| US4133713A (en) * | 1977-10-11 | 1979-01-09 | The Procter & Gamble Company | Microturbulence generator for papermachine headbox |
| DE3227218C2 (en) * | 1982-07-21 | 1984-10-18 | Escher Wyss Gmbh, 7980 Ravensburg | Multi-layer headbox |
| DE3723922C2 (en) * | 1987-07-18 | 1993-10-14 | Trefz Wolfgang Dipl Ing Fh | Turbulence generator for the headbox of a paper machine |
| US5129988A (en) * | 1991-06-21 | 1992-07-14 | Kimberly-Clark Corporation | Extended flexible headbox slice with parallel flexible lip extensions and extended internal dividers |
| US5277765A (en) * | 1992-06-18 | 1994-01-11 | Voith, Inc. | Headbox with a vertical partition between perforated rolls |
| DE4307143C2 (en) * | 1993-03-06 | 1998-02-05 | Voith Gmbh J M | Multi-layer headbox |
| DE4321697C2 (en) * | 1993-06-30 | 2002-05-23 | Voith Paper Patent Gmbh | Turbulence insert of a paper machine |
| DE4402625A1 (en) * | 1994-01-31 | 1994-06-09 | Voith Gmbh J M | Stock inlet flow guide - has an air hose in the mounting for the guide wall to prevent build-up |
-
1996
- 1996-05-25 DE DE19621258A patent/DE19621258C1/en not_active Expired - Fee Related
-
1997
- 1997-04-23 DE DE59710938T patent/DE59710938D1/en not_active Expired - Lifetime
- 1997-04-23 EP EP97106692A patent/EP0812951B1/en not_active Expired - Lifetime
- 1997-05-23 CA CA002206023A patent/CA2206023A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0812951B1 (en) | 2003-11-05 |
| DE19621258C1 (en) | 1997-10-16 |
| DE59710938D1 (en) | 2003-12-11 |
| EP0812951A3 (en) | 1998-04-01 |
| EP0812951A2 (en) | 1997-12-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |