DE10333201A1 - Papermaking dewatering double sieve belt passes over transverse pressure beam subdivided into equal segments with individual pressure control - Google Patents

Abstract

A papermaking headbox discharges a fibrous suspension onto a moving double-sieve (3) belt (2) that is supported by a transverse beam (6) with a first raised edge (4) transverse to the direction of sieve belt travel (S). The transverse beam (6) is sub-divided into a series of identical units (1.1-1.3, 1.N). The raised edge (4) extends from the transverse beam (6) and is supported by lift/lower jacks against a fixed sub-structure. The pressure (p1, p2, p3) with which the raised edge (4) is applied to the moving sieve belt is individually variable for each sector (1.1-1.3).

Description

The The invention relates to a strip for resilient support of a endlessly circulating sieve bands in the area of a twin-wire zone of a Twin-wire former with a headrail, which is perpendicular to the screen direction extends, over which can slide the screen along a Siebberührt surface and with a movable support bar, which is also perpendicular to the wire direction extends, is connected, wherein between the movable support bar and a fixed structure a plurality of resilient and preferably provided in Sieblaufrichtung lifting elements are provided, which the movable support bar together with the head strip between a Rest position and a working position in which the header bar with a selectable one Pressure on the screen belt pressed is, can move.

Farther The invention relates to a twin-wire former of a machine for Production of a fibrous web, in particular a paper or Cardboard web, of at least one pulp suspension, with two circulating endless sieves, in places a double-wire zone form.

Such a bar for the flexible support of a screen belt is from the German patent application DE 40 09 627 A1 (PB04714 DE) of the applicant. However, the lifting element for moving the movable support strip together with head strip extends perpendicular to the direction of wire-winding between the fixed structure and the movable support bar. The lifting element is designed either as a double-acting cylinder or as a pneumatic pressure hose.

disadvantageous At this bar is that due to the machine-wide configuration and effect of the lifting element a sectioned Andrückung the Ledge to the screen belt, thereby creating a profiled CD contact profiles not possible is. As a result, the adaptation of the bar to different CD pulp suspension heights do not possible.

Furthermore, from the European patent specification EP 0 629 740 B1 a machine-wide bar is known, which is adjustable with respect to its deflection in the CD direction by means of pressing a pressure medium, preferably a gaseous pressure medium. The pressures which are preferably different in the CD direction are applied by means of a number of elastic pressure hoses.

The machine-wide bar has the technological disadvantage that They only small deflections due to their strength and structure in the CD direction can be subjected. A profiling of the bar in CD direction so only partially possible.

A twin-wire former of the type mentioned is, for example, from the German Offenlegungsschrift DE 40 05 420 A1 (PB04713 DE) of the applicant. In the twin-wire zone of this twin-wire former, a wire belt runs over rigid strips, which are preferably arranged at a mutual distance on a dewatering box, and a wire belt runs over a plurality of resiliently supported and machine-wide strips of known type.

this Twin-wire former with strips also adheres to the said disadvantage no or only a slight profiling of the strips in the CD direction at.

Of the Invention is based on the object, a bar for yielding support a screen belt of the type mentioned in such a way, that improved profiling of the bar in CD direction and thus adapting the strip to different operating conditions and parameters in achieving the best possible quality characteristics.

In addition, should a suitable twin-wire former for use of the bar according to the invention indicated become.

These Task is solved by that the ledge from several perpendicular to the Sieblaufrichtung next to each other arranged and discrete strip elements with respective header strips and support bar element consists and that each individual strip element of at least one yielding, and preferably in the direction of screen direction running lifting element with an individually selectable pressure acted upon is.

By this subdivision of the bar into a variety of individual and discrete strip elements is a very precise profiling of the strip possible in the CD direction in a larger profiling area. By the assignment of at least one lifting element for a strip element can this due to the individually selectable Pressure can be very accurately moved and fixed, reducing the quality and duration the profiling of the bar in the CD direction is gaining in value. This favored again the avoidance of sheet formation disturbances with uneven layer height cross profile the pulp suspension.

The strip elements preferably have a width perpendicular to the screen direction in the range of 30 to 300 mm, preferably from 50 to 100 mm. As a result, the emergence of any markings in the wire is avoided and created a sufficiently large wetted surface (support surface).

Farther have the strip elements in a further embodiment wetted surfaces same and / or different size and / or same and / or different contour. The respective contour can assume different geometric shapes; she can in particular a square, a rectangle, a triangle, a trapezoid, a parallelogram or the like. Also, she can be a mix of different be geometric shapes. Furthermore, the respective contour can be at least one in edge direction extending edge angle in the range of 0 to 20 °, preferably from 5 to 10 °. So it's possible that the strip elements in the two-sided edge regions of the screen belt have different sizes and contours compared to the middle area.

The Strip elements with preferably the same size and / or same contours are preferably arranged in a pattern. Here are the bar elements with a straight rank offset to the last elements with odd Be arranged rank, wherein the displacement is a rotation to the vertical to the touched area each to be 180 ° can. This arrangement is particularly suitable for strip elements with contours in the form of identical trapezoids.

The Lifting elements for moving the strip elements between one Rest position and a working position preferably have pneumatic, hydraulic and / or mechanical adjusting elements. However, there are also lifting elements with differently operating adjusting elements, for example in shape of electromechanical adjusting elements, possible.

The pneumatic and hydraulic adjusting elements are more advantageous Way as pressure hoses or pressure pad formed, whereas the mechanical adjustment formed in an advantageous manner as eccentric or lever units are.

To the Returning the single strip elements in the corresponding rest position a respective return system, in particular a spring system, provided so that the mobility the header element in every imaginable installation situation and Direction of movement guaranteed is.

Of the individually selectable Pressure for the respective strip element is preferably controlled / controlled and the respective rule / tax quantity is ideally of a parent Rule / control unit specified. This is a high level of automation favored when using the strips and a fast and accurate Adaptation of the profiling of the strips in the CD direction allows.

One suitable twin-wire former of a machine for producing a Fiber web, in particular a paper or board web, from at least one pulp suspension, with two endless circulating Seven, which in places form a double-wire zone, is thereby characterized in that in the twin-wire zone at least one strip according to the invention is arranged. The twin-wire former can be used as gap former or be designed as a hybrid former.

The Variety of strips according to the invention can be offset from each other perpendicular to the screen direction, wherein the offset preferably has a value in the range of 10 to 90%, preferably from 25 to 75%, of the division of the inguinal elements accepts.

Also For example, a sieve belt in the twin-wire zone may have rigid ledges, preferably arranged at a mutual distance on a drainage box, run and a screen belt in the twin-wire zone over at least one strip according to the invention to run. The distance in the direction of wire run between the rigid bars and the strip according to the invention is preferably adjustable.

Further Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference to the drawing.

It demonstrate

1 a schematic perspective view of a strip according to the invention;

2 a CD dewatering pressure trace in the area of a twin wire former;

3 a plan view arranged in staggered rows and inventive strips; and

4A - 4C : A plan view of various strips according to the invention.

The 1 shows a schematic perspective view of a bar 1 for yielding support of a screen belt 2 in the area of a twin-wire zone 3 a not shown Doppelsiebformers.

The bar 1 includes a header 4 which extends perpendicular to the screen direction S (arrow) over which the screen belt 2 along a sieved area 5 Can slide and with a movable support bar 6 , which also extends perpendicular to the screen direction S (arrow), is connected. Between the movable support bar 6 and a fixed and schematically illustrated structure 7 are exemplified several resilient and preferably in Sieblaufrichtung S (arrow) extending lifting elements 8th provided which the movable support bar 6 along with the header 4 between a resting position and a working position in which the header bar 4 with a selectable pressure p to the screen belt 2 is pressable, can move.

The bar 1 consists of several perpendicular to Sieblaufrichtung S (arrow) juxtaposed and discrete strip elements 1.1 . 1.2 . 1.3 with respective header elements 4.1 . 4.2 . 4.3 and support bar elements 6.1 . 6.2 . 6.3 and the single strip element 1.1 . 1.2 . 1.3 is of at least one resilient and preferably in Sieblaufrichtung S (arrow) extending lifting element 8.1 . 8.2 . 8.3 with an individually selectable pressure p ₁ , p ₂ , p ₃ acted upon.

In a further, but not shown embodiment, the lifting element can 8th also over a part of the width or over the entire width of the Doppelsiebformers, that is over the entire length of the bar 1 extend, wherein the local bulge of the lifting element may be different upwards, for example due to different local material properties or due to appropriate and locally acting limiting devices.

The bar elements 1.1 . 1.2 . 1.3 in 1 have a width B ₁ , B ₂ , B ₃ perpendicular to the wire direction S (arrow) in the range of 30 to 300 mm, preferably from 50 to 100 mm, and wetted surfaces 5.1 . 5.2 . 5.3 same size and contour. The contour shown is a rectangle or a square.

The individually selectable pressure p ₁ , p ₂ , p ₃ for the respective strip element 1.1 . 1.2 . 1.3 is regulated / controlled and the respective rule / control variable is from a higher level control / control unit 9 specified. The parent rule / control unit 9 may in turn be part of a known process control system (PLS). Such a control is well known to those skilled in the art.

In the embodiment according to 1 are the lifting elements 8.1 . 8.2 . 8.3 pneumatic adjusting elements 10.1 . 10.2 . 10.3 , The pneumatic adjusting elements 10.1 . 10.2 . 10.3 are designed as pressure hoses or pressure pad. The Hub elements may of course also have hydraulic and / or mechanical adjusting elements, wherein the mechanical adjusting elements are preferably designed as eccentric or lever units.

For returning the individual bar elements 1.1 . 1.2 . 1.3 in the corresponding rest position is a respective return system 11.1 . 11.2 . 11.3 , in particular a spring system provided. The respective return system 11.1 . 11.2 . 11.3 is only shown by an arrow.

The 2 shows a CD dewatering pressure curve p _CD in the region of a twin wire former. On the left side of the abscissa is the drive side TS and on the right side of the abscissa is the guide page FS applied. The ordinate shows the drainage pressure curve p _CD in [bar].

It can be clearly seen that the CD-dewatering pressure curve p _{CD has} great variations when using conventional strips (dashed line), whereas it can be kept uniform or at least approximately uniform when using the strip elements according to the invention (solid line). For certain requirements, even a profiling of the CD dewatering pressure p _{CD is} possible.

The 3 shows a top view of in perpendicular to the wire direction S (arrow) offset rows R ₁ , R ₂ , R ₃ arranged strips 1 with a variety of strip elements 1.1 to 1.N , The respective offset V takes a value in the range of 10 to 90%, preferably 25 to 75%, of the pitch T of the strip elements 1.1 to 1.N at. The bar elements 1.1 to 1.N have wetted surfaces 5.1 to 5.N of the same size and the same contour in the form of rectangles and are arranged in the twin-wire zone of a Doppelsiebformers.

The individual rows R ₁ , R ₂ , R _{3 of} the last 1 with a variety of strip elements 1.1 to 1.N can each with different and independent lifting elements 8th be provided.

The 4A to 4C each show a plan view of various strips according to the invention 1 with a variety of strip elements 1.1 to 1.N , The illustrated strip elements 1.1 to 1.N have wetted surfaces 5.1 to 5.N same size and contour. In the execution of 4A the contour is a parallelogram in which the 4B a trapeze and in the 4C turn a trapeze. Of course it is also possible that a bar 1 a variety of strip elements 1.1 to 1.N having different contours. Furthermore, all contours of the 4A to 4C at least one in the direction of wire direction S (arrow) extending edge angle α in the range of 0 to 20 °, preferably from 5 to 10 °.

The in the 4C shown bar elements 1.2 . 1.4 . 1.6 with even rank are offset to the inguinal elements 1.1 . 1.3 . 1.5 arranged with odd rank. The offset is in this case a rotation (turnstile) to the vertical to Siebberührung surface 5.2 . 5.4 . 5.6 each 180 °. However, the offset may also take on at least one other value for other contours.

The strip according to the invention can also be used in a twin-wire former of a machine for manufacturing a fibrous web, in particular a paper or board web, from at least one pulp suspension, with two circulating endless seven, which in places form a double-wire zone, his Apply by placing them several times in the twin-wire zone are.

there For example, in the twin-wire zone, a sieve belt can be used over rigid strips, preferably arranged at a mutual distance on a drainage box, and a screen belt over several strips of the invention to run. The distance in the direction of wire run between the rigid bars and the strips according to the invention can be adjustable.

Such a twin-wire former is known from the already mentioned publication DE 40 05 420 A1 (PB04713 DE) of the applicant. The content of this publication is hereby made the subject of the present description.

In summary It should be noted that the invention provides a strip for resilient support of a Siebbands of the type mentioned is created, which improved Profiling in CD direction and thus their adaptation to different Operating conditions and parameters in achieving the best possible quality features allows becomes.

LIST OF REFERENCE NUMBERS

1

strip

1.1 to 1.6, 1.N

bar item

2

screen belt

3

twin

4

header

4.1 4.2, 4.3

The headliner element

5

Sieve-touched area

5.1 to 5.6, 5.N

Sieve-touched area

6

supporting strip

6.1 6.2, 6.3

Supporting bar item

7

structure

8th

lifting

8.1 8.2, 8.3

lifting

9

Regulation / control unit

10.1, 10.2, 10.3

adjustment

11.1, 11.2, 11.3

return system (Arrow)

B ₁ , B ₂ , B ₃

width

FS

tender side

p

print

p ₁ , p ₂ , p ₃

print

p _CD

CD dewatering pressure profile

R ₁ , R ₂ , R ₃

line

S

wire running (Arrow)

T

division

TS

drive side

V

transfer

α

edge angle

Claims (19)

Strip ( 1 ) for the flexible support of an endlessly circulating screen belt ( 2 ) in the region of a twin-wire zone ( 3 ) of a twin wire former with a head strip ( 4 ) extending perpendicular to the screen direction (S), over which the screen belt ( 2 ) along a wetted surface ( 5 ) and that with a movable support bar ( 6 ), which also extends perpendicular to the screen direction (S) is connected, wherein between the movable support bar ( 6 ) and a fixed structure ( 7 ) a plurality of resilient and preferably in Sieblaufrichtung (S) extending lifting elements ( 7 ) are provided, which the movable support bar ( 6 ) together with the header ( 4 ) between a rest position and a working position, in which the head strip ( 4 ) with a selectable pressure (p) to the screen belt ( 2 ) is pressable, can shift, characterized in that the bar ( 1 ) of a plurality of perpendicular to Sieblaufrichtung (S) juxtaposed and discrete strip elements ( 1.1 to 1.6 . 1.N ) with respective header element ( 4.1 . 4.2 . 4.3 ) and support bar element ( 6.1 . 6.2 . 6.3 ) and that each individual strip element ( 1.1 to 1.6 . 1.N ) of at least one resilient and preferably in Sieblaufrichtung (S) extending stroke element ( 7.1 . 7.2 . 7.3 ) with an individually selectable pressure (p ₁ , p ₂ , p ₃ ) can be acted upon. Strip ( 1 ) according to claim 1, characterized in that the strip elements ( 1.1 to 1.6 . 1.N ) have a width (B) perpendicular to the wire-winding direction (S) in the range of 30 to 300 mm, preferably 50 to 100 mm. Strip ( 1 ) according to claim 1 or 2, characterized in that the strip elements ( 1.1 to 1.6 . 1.N ) touched surfaces ( 5.1 to 5.6 . 5.N ) have the same and / or different size. Strip ( 1 ) according to claim 1, 2 or 3, characterized characterized in that the strip elements ( 1.1 to 1.6 . 1.N ) touched surfaces ( 5.1 to 5.6 . 5.N ) have the same and / or different contour. Strip ( 1 ) according to claim 4, characterized in that the contour is a square, a rectangle, a triangle, a trapezoid, a parallelogram or the like. Strip ( 1 ) according to claim 5, characterized in that the contour has at least one edge angle (α) extending in the direction of wire-winding direction (S) in the range from 0 to 20 °, preferably from 5 to 10 °. Strip ( 1 ) according to one of the preceding claims, characterized in that the strip elements ( 1.1 to 1.6 . 1.N ) are arranged with preferably the same size and / or same contours in a pattern. Strip ( 1 ) according to claim 7, characterized in that the strip elements ( 1.2 . 1.4 . 1.6 ) with a straight rank offset to the strip elements ( 1.1 . 1.3 . 1.5 ) are arranged with odd rank. Strip ( 1 ) according to claim 8, characterized in that the displacement is a rotation to the perpendicular to the sieved surface ( 5.2 . 5.4 . 5.6 ) is in each case 180 °. Strip ( 1 ) according to one of the preceding claims, characterized in that the lifting elements ( 7.1 . 7.2 . 7.3 ) pneumatic, hydraulic and / or mechanical adjusting elements ( 10.1 . 10.2 . 10.3 ) exhibit. Strip ( 1 ) according to claim 10, characterized in that the pneumatic and hydraulic adjusting elements ( 10.1 . 10.2 . 10.3 ) are designed as pressure hoses or pressure pad. Strip ( 1 ) according to claim 10, characterized in that the mechanical adjusting elements ( 10.1 . 10.2 . 10.3 ) are designed as eccentric or lever units. Strip ( 1 ) according to one of the preceding claims, characterized in that for returning the individual strip elements ( 1.1 to 1.6 . 1.N ) in the corresponding rest position, a respective return system ( 11.1 . 11.2 . 11.3 ), in particular a spring system, is provided. Strip ( 1 ) according to one of the preceding claims, characterized in that the individually selectable pressure (p ₁ , p ₂ , p ₃ ) for the respective strip element ( 1.1 to 1.6 . 1.N ) is regulated / regulated and that the respective rule / control variable from a higher-level rule / control unit ( 9 ) is given. Twin-wire former of a machine for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension, with two continuous endless sieves, which in some cases form a double-wire zone ( 3 ), characterized in that in the twin-wire zone ( 3 ) at least one bar ( 1 ) is arranged according to at least one of the preceding claims. Twin-wire former according to claim 15, characterized in that a plurality of strips ( 1 ) according to at least one of claims 1 to 13 are arranged perpendicular to the screen direction (S) offset from one another. Twin-wire former according to claim 14, characterized in that the offset (V) has a value in the range from 10 to 90%, preferably from 25 to 75%, of the pitch (T) of the strip elements ( 1.1 to 1.6 . 1.N ). Twin-wire former according to one of claims 15, 16 or 17, characterized in that a screen belt ( 2 ) in the twin-wire zone ( 3 ) on rigid strips, which are preferably arranged at a mutual distance on a drainage box, running and that a screen belt ( 2 ) in the twin-wire zone ( 3 ) via at least one bar ( 1 ) according to at least one of claims 1 to 13 runs. Twin-wire former according to claim 18, characterized in that the distance in the wire direction (S) between the rigid strips and the strips ( 1 ) is adjustable according to at least one of claims 1 to 13.