CA1243232A - Flow restraining elements in the headbox of a paper machine - Google Patents
Flow restraining elements in the headbox of a paper machineInfo
- Publication number
- CA1243232A CA1243232A CA000473323A CA473323A CA1243232A CA 1243232 A CA1243232 A CA 1243232A CA 000473323 A CA000473323 A CA 000473323A CA 473323 A CA473323 A CA 473323A CA 1243232 A CA1243232 A CA 1243232A
- Authority
- CA
- Canada
- Prior art keywords
- restraining elements
- chamber
- flow restraining
- headbox
- flow
- 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.)
- Expired
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- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A headbox for a paper machine comprising a top plate and a bottom plate defining a chamber therebetween and a plurality of flow restraining elements disposed one above another in the chamber to define a plurality of paths spaced one above another therein. The top and bottom plates are connected to one end to a perforated plate defining an inlet for the chamber and approach each other as they approach an outlet for the chamber. Each element is removably connected at one end to the perforated plate, and the paths extend from the inlet to the outlet. Each element has a mildly corrugated upper surface and a mildly corrugated lower surface which approach each other until they terminate in a free end remote from the perforated plate. Those surfaces are substantially symmetrical to each other with respect to a center line of said element. Each element has a free end portion formed from an easily deformable material, such as rubber or plastics.
The surfaces of each element define an angle of 1° to 15°
therebetween.
A headbox for a paper machine comprising a top plate and a bottom plate defining a chamber therebetween and a plurality of flow restraining elements disposed one above another in the chamber to define a plurality of paths spaced one above another therein. The top and bottom plates are connected to one end to a perforated plate defining an inlet for the chamber and approach each other as they approach an outlet for the chamber. Each element is removably connected at one end to the perforated plate, and the paths extend from the inlet to the outlet. Each element has a mildly corrugated upper surface and a mildly corrugated lower surface which approach each other until they terminate in a free end remote from the perforated plate. Those surfaces are substantially symmetrical to each other with respect to a center line of said element. Each element has a free end portion formed from an easily deformable material, such as rubber or plastics.
The surfaces of each element define an angle of 1° to 15°
therebetween.
Description
~Z~3Z3~
.
FLOW RESTRAINING ELEMENTS IN THE HEADBOX
OF A PAPER MA~HINE
BACKGROUND OF THE INVENTION
, 1~ Field of the Invention~
.
This invention rel~tes to a headbox in a paper machine.
More particularly, i~ relates to flow restraining Plements in the ~l~adboxO
BRIEF DESC RI PTION OF THE ~RAWINGS
FIGURE t is a longitudinal and vertical sectional view 1~ of a paper machine headbox known in the art, and FIGURE 2 is a longitudinal and vertical sectional view o~E a headbox embodying ~his inventionO
.
FLOW RESTRAINING ELEMENTS IN THE HEADBOX
OF A PAPER MA~HINE
BACKGROUND OF THE INVENTION
, 1~ Field of the Invention~
.
This invention rel~tes to a headbox in a paper machine.
More particularly, i~ relates to flow restraining Plements in the ~l~adboxO
BRIEF DESC RI PTION OF THE ~RAWINGS
FIGURE t is a longitudinal and vertical sectional view 1~ of a paper machine headbox known in the art, and FIGURE 2 is a longitudinal and vertical sectional view o~E a headbox embodying ~his inventionO
2. D3scription of the Prior Art:
..~ conventional headbox for a paper machine is shown by 1~ ~ay o:E example in FIGURE lo It comprises a top plate 2 and a botrom plata 3 defining therebetween ~ chamber in which a plurality of flow restraining element~ 1 are provided one above another. æach elsment 1 is held at one end by one of a plurality of grooves formed in a perforated plate 4 disposed 2~ upstream of the elements lo The f low of a raw paper li~uid in the chamber maintains the elements 1 in their positions shown in FIGURE 1. The slements 1 define a plurality of paths 5. Those portions of the paper material which flow A
..~ conventional headbox for a paper machine is shown by 1~ ~ay o:E example in FIGURE lo It comprises a top plate 2 and a botrom plata 3 defining therebetween ~ chamber in which a plurality of flow restraining element~ 1 are provided one above another. æach elsment 1 is held at one end by one of a plurality of grooves formed in a perforated plate 4 disposed 2~ upstream of the elements lo The f low of a raw paper li~uid in the chamber maintains the elements 1 in their positions shown in FIGURE 1. The slements 1 define a plurality of paths 5. Those portions of the paper material which flow A
3~32 1 through the paths 5 meet downstream of the elements 1, and it is ejected onto a wire not shown after its degree of open-ing has been controlled by a slice lip 6.
A plurality of paths defined by a plurality of ~low restraining elements enable the effective dispersion of fibers in the liquid with a small head loss and thereby the prod~lction of paper of high qualityO
The known flow restraining elements as shown a~ 1 in ~IGURE 1, however, has a number of drawbacks. They are dif-ficult to make because of their large variation in thic~nessO
; They easily get warped along their width. Correctly sizedpaths are, ~herefore, difficult to define. The elements break easily a~ any portion of reduced thic]cnessO Those por-tlons of the elements at which they are connected to the 15 perforated plate are so small in thickness t:hat they easily get deformed and are difficult to attach to, or de~ach from, the perforated plate.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an improved 20 headbox for ~ paper machine including improved flow restrain-ing elements which are easy to make and define correctly sized paths.
This invention provides an improvement in a paper machine headb~x comprising a top plate and a bottom plate connected at one end to a perforated plate, defining a chamber there-between and approaching each other toward a slice lip, and ~ .
3lZ~3~32 1 a plurality of flow restraining elements disposed in the chamber to define a plurality of paths therein and each re-movably connected at one end to the perforated plate through which a liquid paper material is introduced into the pathsO
~ ccording to a saLiant feature of this invention, each flow restraining element has a thickness which gradually ~ecreases as i-t becomes farther from the perforated plateO
This gradually decreasing thickness is defined by an upper surface and a lower surface which approach each other until Lq the~ join each other a~ the free end of the e~ementO The up-per and lower surfaces have a substantially e~ual mildly cor-rugated pattern and the corruga~ions on each surface. extend p~ a downstream d~rectio~ . `
At least that portion o~ each e~ement which ~ermina~es in its free end is formed from an easily deformable material, such as rubber or plastics, so that t;hat portion may be easily deformable along the width of the elementO
The upper and lower surfaces of each slement pr~ferably define an angle of 1 to 15 ~herebetweenO
~0 Each element has a gradually decreasing ~hickness and its upper and lower surfaces are miidly corrugated. In other words, its thickness varies only to a small extentO Its upper and lower surfaces are substantially symmetrical to each other with respect to a ce~er li.ne of sa~d element.
Therefors, the elements are not appreciably warped when they are made. They are not appreciably warped despite variation in temperature during the operation of the paper machineO
- ~L2~3~3~
1 Insofar as they are not ea~ily warped, they are easy to make and ensure that correctly siz~d paths be maintained.
= -Tha~ portion of Pach element which ~erminates in its free end is formed from an sasily deformable material, such as rubber or plastics, and has a very small thicknessO Therefore9 the warpage of the elemen~, if any, is easily rectified by its deformation w~en the liguid ~aper material is caused to flow through the pa~hs, this feature contributes ~o ensuring the correct dimens:ions of the pathsO
The elements have a gradually decreasing thickness and its sur~aces are m:Lldly corrugated and do not define any por-tion that is extremely thick or thinO Therefors, they are not easily broken, while they are light in weight and easy to handle. That erld of each element at which it i5 connected 15 to the perforated ~>late has a sufficiently large thic~ness not to be easily bent~ and is9 therefore, easy to connect to, or disconnect from, the perforated pla~e, Other features and advantages of this invention will become apparent from the following description and the ac companying drawings.
DETAILED DESCRIPTION OF THE INVENTION
A headbox embodying this invention is shown by way of
A plurality of paths defined by a plurality of ~low restraining elements enable the effective dispersion of fibers in the liquid with a small head loss and thereby the prod~lction of paper of high qualityO
The known flow restraining elements as shown a~ 1 in ~IGURE 1, however, has a number of drawbacks. They are dif-ficult to make because of their large variation in thic~nessO
; They easily get warped along their width. Correctly sizedpaths are, ~herefore, difficult to define. The elements break easily a~ any portion of reduced thic]cnessO Those por-tlons of the elements at which they are connected to the 15 perforated plate are so small in thickness t:hat they easily get deformed and are difficult to attach to, or de~ach from, the perforated plate.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an improved 20 headbox for ~ paper machine including improved flow restrain-ing elements which are easy to make and define correctly sized paths.
This invention provides an improvement in a paper machine headb~x comprising a top plate and a bottom plate connected at one end to a perforated plate, defining a chamber there-between and approaching each other toward a slice lip, and ~ .
3lZ~3~32 1 a plurality of flow restraining elements disposed in the chamber to define a plurality of paths therein and each re-movably connected at one end to the perforated plate through which a liquid paper material is introduced into the pathsO
~ ccording to a saLiant feature of this invention, each flow restraining element has a thickness which gradually ~ecreases as i-t becomes farther from the perforated plateO
This gradually decreasing thickness is defined by an upper surface and a lower surface which approach each other until Lq the~ join each other a~ the free end of the e~ementO The up-per and lower surfaces have a substantially e~ual mildly cor-rugated pattern and the corruga~ions on each surface. extend p~ a downstream d~rectio~ . `
At least that portion o~ each e~ement which ~ermina~es in its free end is formed from an easily deformable material, such as rubber or plastics, so that t;hat portion may be easily deformable along the width of the elementO
The upper and lower surfaces of each slement pr~ferably define an angle of 1 to 15 ~herebetweenO
~0 Each element has a gradually decreasing ~hickness and its upper and lower surfaces are miidly corrugated. In other words, its thickness varies only to a small extentO Its upper and lower surfaces are substantially symmetrical to each other with respect to a ce~er li.ne of sa~d element.
Therefors, the elements are not appreciably warped when they are made. They are not appreciably warped despite variation in temperature during the operation of the paper machineO
- ~L2~3~3~
1 Insofar as they are not ea~ily warped, they are easy to make and ensure that correctly siz~d paths be maintained.
= -Tha~ portion of Pach element which ~erminates in its free end is formed from an sasily deformable material, such as rubber or plastics, and has a very small thicknessO Therefore9 the warpage of the elemen~, if any, is easily rectified by its deformation w~en the liguid ~aper material is caused to flow through the pa~hs, this feature contributes ~o ensuring the correct dimens:ions of the pathsO
The elements have a gradually decreasing thickness and its sur~aces are m:Lldly corrugated and do not define any por-tion that is extremely thick or thinO Therefors, they are not easily broken, while they are light in weight and easy to handle. That erld of each element at which it i5 connected 15 to the perforated ~>late has a sufficiently large thic~ness not to be easily bent~ and is9 therefore, easy to connect to, or disconnect from, the perforated pla~e, Other features and advantages of this invention will become apparent from the following description and the ac companying drawings.
DETAILED DESCRIPTION OF THE INVENTION
A headbox embodying this invention is shown by way of
4 -lZat3Z~2 example in FIGURE 2. It comprises a plurality of flow re-straining elements 7 disposed one above another in a chamber defined between a top plate 8 and a bottom plate 9. Each element 7 is connected at one end to a perforated plate 10 defining an inlet for the chamber.
Each element 7 has a mildly corrugated upper surface and a substantially equally mildly corrugated lower surface.
The upper and lower surfaces approach each other gradually until they terminate in a free end located remotely from the perforated plate 10 and in the vicinity of an outlet for the chamber. The surfaces preferably define an angle of 1 to 15 therebetween. If this angle is smaller than 1, it is difficult to form each element 7 and particularly its free end portion with satisfactorily corrugated surfaces which create a satisfactory stirring effect on the liquid which is caused to flow through the paths defined by the elements 7.
I~ the angle is larger than 15, that end of each element 7 at which it is connected to the perforated plate 10 is too large in thickness and makes the element heavy and difficult to handle. The upper and lower surfaces of each element 7 shown in FIGURE 2 have an angle of about 4 therebetween by way of example.
The corrugated surfaces are defined by corrugations which extend to a downstream direction. The corrugated serfaces serve to 1~3~32 create a turbulent flow in the liquid. They define paths hav-ing a cross sectional configuration which gradually increases or decreases along the elements 7 and thereby causes the liquid to flow at a speed which decreases and increases along the paths. The dimensions of the corrugations are so selected as to ensure that the thickness of each element 7 vary mildly.
The corrugatad upper and lower surfaces are substantially symmetrical to each other with respect to a longitudinal axis of said element.
The free end portion of each element 7, which has a very small thickness, is formed from a material having a low modulus of elasticity and a specific gravity close to 1, such as rubber or plastics, so that it may be easily deformable.
The other portion may be formed from the same material, or any other material.
Each element 7 has a mildly corrugated upper surface and a substantially equally mildly corrugated lower surface.
The upper and lower surfaces approach each other gradually until they terminate in a free end located remotely from the perforated plate 10 and in the vicinity of an outlet for the chamber. The surfaces preferably define an angle of 1 to 15 therebetween. If this angle is smaller than 1, it is difficult to form each element 7 and particularly its free end portion with satisfactorily corrugated surfaces which create a satisfactory stirring effect on the liquid which is caused to flow through the paths defined by the elements 7.
I~ the angle is larger than 15, that end of each element 7 at which it is connected to the perforated plate 10 is too large in thickness and makes the element heavy and difficult to handle. The upper and lower surfaces of each element 7 shown in FIGURE 2 have an angle of about 4 therebetween by way of example.
The corrugated surfaces are defined by corrugations which extend to a downstream direction. The corrugated serfaces serve to 1~3~32 create a turbulent flow in the liquid. They define paths hav-ing a cross sectional configuration which gradually increases or decreases along the elements 7 and thereby causes the liquid to flow at a speed which decreases and increases along the paths. The dimensions of the corrugations are so selected as to ensure that the thickness of each element 7 vary mildly.
The corrugatad upper and lower surfaces are substantially symmetrical to each other with respect to a longitudinal axis of said element.
The free end portion of each element 7, which has a very small thickness, is formed from a material having a low modulus of elasticity and a specific gravity close to 1, such as rubber or plastics, so that it may be easily deformable.
The other portion may be formed from the same material, or any other material.
Claims (8)
- Claim 1 continued....
restraining elements, said recessed portions being located between said perforated plate and said surface portions of said flow restraining elements having said corrugated patterns, and said flow restraining elements being positioned in said chamber with said corrugated patterns symmetrical with respect to each other, whereby the flow paths between adjacent flow restraining elements have cross-sectional configurations which gradually increase and gradually decrease, thus causing liquid which flows between said flow restraining elements in said downstream direction to have a speed which decreases and increases to create a stirring effect on the liquid. - 2. The improved headbox of claim 1, wherein each of said flow restraining elements consist entirely of plastic.
- 3. The improved headbox of claim 1, wherein said angle between said upper surface and said lower surface is 4°.
- 4. The improved headbox of claim 1, wherein said perforated plate has a surface forming an inside wall of said chamber, said surface of said perforated plate being convex in shape towards said flow restraining elements.
5. The improved headbox of claim 1, wherein the most upstream one of said reduced cross section portions has a - Claim 5 continued....
cross section greater than that of the most downstream one of said increased cross section portions. - 6. The improved headbox of claim 1, wherein said upper and lower surfaces diverge from each other in a downstream direction respectively from said upper and lower walls.
- 7. The improved headbox of claim 1, wherein said upper and lower walls are spaced from said perforated plate at locations downstream of said perforated plate.
- 8. The improved headbox as in claim 1, wherein said top plate has a corrugated inner surface which is substantially symmetrical to said upper surface of the uppermost element, while said bottom plate has a corrugated inner surface which is substantially symmetrical to said lower surface of the lowermost element with respect to a substantially horizontal plane.
1. In a headbox for a paper making machine, the headbox having a top plate and a bottom plate defining a chamber therebetween, a perforated plate connected. to an inlet end of said top plate and an inlet end of said bottom plate to form an inlet of said chamber, said top plate and said bottom plate approaching each other at an outlet end spaced from said inlet end to form an outlet of said chamber, and a plurality of flow restraining elements disposed one above another in said chamber to define a plurality of flow paths spaced one above another in said chamber, said flow restraining elements extending from said inlet to said outlet, having free ends at said outlet, and being removably connected at one end thereof to said perforated plats, the improvement wherein;
each of said flow restraining elements has an upper surface and a lower surface which approach each other until they meet at said free end in a downstream direction away from said perforated plate toward said outlet end, said upper and lower surfaces each having a surface portion having corrugated patterns which are symmetrical with respect to each other and formed by a cross section perpendicular to said downstream direction, which alternately gradually increases and decrease along the length of said flow restraining elements to said free end so Claim 1 continued....
as to define alternating portions of increased and reduced cross section, such that the increased cross sections gradually decrease in said downstream direction and the decreased cross sections gradually decrease in said downstream direction, said cross sections varying sufficiently gradually between successive portions of increased and reduced cross section so as to resist warping during variable temperature use, said upper surface and said lower surface defining an angle of 1° to 15° therebetween, said free ends of said flow restraining elements being formed from a flexible material selected from the group of flexible material consisting of rubber and plastic, said material having a low modulus of elasticity and a specific gravity of about 1.0 so as to be easily deformable, each of said flow restraining elements being provided with an upper recessed portion on said upper surface and a lower recessed portion on said lower surface, said upper and lower recessed portions being respectively defined by an upper wall on said upper surface and a lower wall on said lower surface which are substantially perpendicular to said downstream direction, said flow restraining element being arranged in said chamber with said recessed portions adjacent one another to create an abruptly enlarged area in each of said paths between adjacent flow
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000473323A CA1243232A (en) | 1985-01-31 | 1985-01-31 | Flow restraining elements in the headbox of a paper machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000473323A CA1243232A (en) | 1985-01-31 | 1985-01-31 | Flow restraining elements in the headbox of a paper machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1243232A true CA1243232A (en) | 1988-10-18 |
Family
ID=4129728
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000473323A Expired CA1243232A (en) | 1985-01-31 | 1985-01-31 | Flow restraining elements in the headbox of a paper machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1243232A (en) |
-
1985
- 1985-01-31 CA CA000473323A patent/CA1243232A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |