US3535203A - Hole plate for one-sided inlet headboxes for paper machines - Google Patents

Hole plate for one-sided inlet headboxes for paper machines Download PDF

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Publication number
US3535203A
US3535203A US805106*A US3535203DA US3535203A US 3535203 A US3535203 A US 3535203A US 3535203D A US3535203D A US 3535203DA US 3535203 A US3535203 A US 3535203A
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US
United States
Prior art keywords
hole
plate
distribution pipe
pulp
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 - Lifetime
Application number
US805106*A
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English (en)
Inventor
Nils Ake Nilsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Metso Fiber Karlstad AB
Original Assignee
Karlstad Mekaniska Ab
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Filing date
Publication date
Application filed by Karlstad Mekaniska Ab filed Critical Karlstad Mekaniska Ab
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Publication of US3535203A publication Critical patent/US3535203A/en
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    • 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
    • D21F1/024—Details of the feed chamber
    • 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
    • D21F1/026—Details of the turbulence section

Definitions

  • a hole plate for a paper-making machine head-box or the like comprises a plurality of holes for conducting stock from a distribution pipe generally aligned with the plate to the head-box and a recess formed adjacent each hole in the surface of the plate and facing the distribution pipe.
  • the recess for each hole merges at one end into the hole at its downstream end, relative to the direction of stock flow through the distribution pipe, and extends from the said downstream edge of the hole in a direction substantially aligned with the flow path of stock through the distribution pipe for a distance downstream of the hole substantially greater than the diameter of the hole.
  • the downstream edge of the recess merges smoothly into the surface of the plate.
  • the recess associated with each hole provides a stagnation point in stock flow that is located at a zone downstream from the edge of the hole so that there is no opportunity for obstruction of the hole and for formation of fiber bundles.
  • the present invention relates to hole plates for onesided inlet headboxes for paper machines.
  • One-sided inlet headboxes are usually at their inlet end provided with a distribution pipe, to which the pulp, i.e. the fibre suspension, is supplied from the one side in a direction substantially perpendicular to the flow direction of the pulp in the headbox.
  • a perforated hole plate is arranged perpendicular to the flow direction of the pulp in the headbox and thus substantially parallel to the flow direction of the pulp in the distribution pipe.
  • the object of this hole plate is to deflect the pulp flow about 90 and to distribute the pulp uniformly over the breadth of the headbox.
  • Hole plates of this kind are provided with a large number of holes for the pulp uniformly spaced over the plate and these holes are often somewhat tapered at the surface of the hole plate facing the distribution pipe.
  • This fibre bundle can become so substantial that it has a detrimental effect upon ice the flow through the hole and when it finally gets large enough to be pulled away from the edge of the hole, it will be carried by the pulp flow through the hole and the headbox out onto the wire of the paper machine and give cause to an uneven fibre distribution and thus a poor quality of the paper produced.
  • the principal object of the present invention is, therefore, to provide a hole plate of the above described type but of an improved design so that the above mentioned stagnation point at each hole is displaced to an even surface, whereby the above stated disadvantages with prior hole plates will be eliminated.
  • a hole plate according to the invention is provided with a recess, in conjunction with each hole in the plate, in the surface of the plate facing the distribution pipe, said recess being downstream from the hole and having a length in the flow directions of the pulp in the distribution pipe substantially exceeding the diameter of the hole.
  • the bottom of the recess is either straight or smoothly curved and merges smoothly into the surface of the hole plate, whereby the stagnation point downstream of each hole will be located at a smooth surface spaced from the downstream edge of the hole. In this stagnation point there is no risk that a fibre bundle will accumulate as there is no sharp edge in this point, against which fibres and fibre threads can get sufiicient friction to adhere.
  • the recess is in the surface of the hole plate facing the distribution pipe are preferably shaped to have a substantially trinagular cross section in planes perpendicular to the plate and parallel to the principal flow direction of the pulp in the distribution pipe.
  • This triangular cross section is characterized by a mainly straight up-stream side approximately perpendicular to the plane of the plate and intersecting the surface of the plate at the up-stream edge of the hole, and by a mainly straight down-stream side forming an angle of at the most 30 and preferably between 10 and 15 with the plane of the plate.
  • the lowermost point in the recess lies at a depth below the surface of the plate of at least 25%, preferably between 50 and of the diameter of the hole, whereby the downstream side of the traingular cross section intersects the surface of the plate at an appreciable distance from the down-stream edge of the hole.
  • the holes in the plate are usually arranged in several rows extending across the plate perpendicular to the flow direction of the pulp in the distribution pipe, and accord ing to the invention the recesses at the holes in the surface of the plate facing the distribution are then preferably achieved by providing this surface, for each row of holes, with a groove having the above mentioned triangular cross section and extending parallel along said row of holes.
  • the recesses in the surface of the plate are formed by such grooves, it may also be advantageous to arrange the holes in the plate in rows extending across the plate obliquely to the direction of the flow in the distribution pipe, whereby also the grooves in the surface of the plate facing the distribution pipe will extend obliquely ot the direction of the flow in the distribution pipe.
  • FIG. 1 is a schematic side view of the headbox with the distribution pipe and the wet end portion of the Wire in a paper machine
  • FIG. 2 shows schematically the headbox with the distribution pipe seen from above
  • FIG. 3 is a cross section, perpendicular to the plane of the plate and parallel to the direction of the flow in the distribution pipe, of a hole plate of a prior design
  • FIG. 4 is a corresponding cross section through a hole plate according to the invention.
  • FIGS. and 6 are schematic plan views of two different designs of a hole plate according to the invention seen from the side of the plate facing the distribution pipe.
  • FIG. 1 shows the inlet end of a paper machine with the wet end portion of the wire 1 and a headbox 2 of conventional type.
  • the headbox 2 is supplied with pulp introduced from one side through a distribution pipe 3 attached to the rear side (as viewed in FIG. 1) of the headbox.
  • the distribution pipe 3 extends over the whole width of the headbox 2 and is at its one end provided with an inlet opening 4 for the pulp.
  • a hole plate 5 is mounted perpendicular to the flow direction in the headbox 2.
  • the hole plate 5 is provided with a large number of holes 6 evenly distributed across the plate. The pulp flowing into the distribution pipe 3 through the inlet opening 4 will pass through the openings 6 in the hole plate 5 and flow into the headbox 2.
  • the function of the hole plate 5 is thus to deflect the pulp flow about 90 and at the same time to distribute the pulp uniformly across the entire width of the headbox 2.
  • the pul is supplied to the distribution pipe 3 in excess of that entering the headbox 2 and the pulp not passing through the hole plate 5 into the headbox leaves the distribution pipe 3 at its opposite end through an outlet Opening 7, from which the pulp is returned to the inlet 4. In this way a more favourable flow pattern is achieved at the end of the distribution pipe opposite the inlet opening 4.
  • the cross sectional area of the distribution pipe 3 decreases continuously from the inlet 4 to the outlet 7 in correspondence with the decreasing volume of the pulp flow.
  • the pulp in the distribution pipe 3 has consequently a flow direction substantially parallel to the hole plate 5 except in the vicinity of the holes 6, where a deflection of the flow takes lace.
  • FIG. 3 is a cross section view through a hole plate of an exemplary prior art design.
  • the cross section is taken perpendicular to the plane of the plate and parallel to the direction of the flow in the distribution pipe 3'.
  • the holes 6' in the hole plate 5' are usually somewhat tapered at the surface 8' of the plate facing the distribution pipe 3'.
  • some of the flow (arrows 9') in the distribution pipe will be deflected into the hole 6.
  • the division of the pulp flow at a hole 6 in one portion flowing into and through the hole 6 and in one portion passing along the surface 8' of the plate 5 will with this design of the hole plate take place at the sharp down-stream edge 10 of the hole.
  • FIG. 4 which is a cross section corresponding to FIG. 3, shows a preferred design of a hole plate according to the invention.
  • the surface 8 of the plate 5 facing the distribution pipe 3 is recessed down stream of each hole 6 so that the down-stream edge 10 of the hole is disposed below the surface 8 of the plate and so that down-stream of the hole 6 a surface 12 is formed, which extends down-stream of the hole over a considerable distance as compared with the diameter d of the hole and which forms a small acute angle a with the surface 8 of the plate 5.
  • the sloping surface 12 is straight. From an operational point of view, however, nothing prevents that this surface is somewhat curved, provided it does not have any pronounced edge, on which fibres can collect. From a manufacturing point of view, however, it is advantageous that the sloping surface 12 is straight.
  • the angle a between the surface 12 and the surface 8 of the plate 5 should not exceed 30 and should preferably lie between 10 and 15. In FIG. 4 the angle a is 12.
  • the recess in the surface 8 of the plate 5 at each hole 6 is preferably shaped so as to have a triangular cross section in a plane perpendicular to the plane of the plate and parallel to the principal direction of the flow in the distribution pipe 3.
  • the up-stre'am side 14 of the recess can be approximately perpendicular to the plane of the plate and should intersect the surface 8 of the plate at the up-stream edge 15 of the hole 6, whereas the down-stream side of the recess forms the sloping surface 12 and thus the acute angle a with the plane of the plate.
  • the largest depth b of the recess below the surface 8 of the plate should amount to at least 25% of the diameter d of the hole 6 and preferably lie between 50 and of this diameter.
  • the depth b of the recess is /3 of the hole diameter d.
  • the sides 12 and 14 of the recess are preferably perpendicular to each other.
  • FIG. 5 shows a hole plate according to the invention seen perpendicular to the plane of the plate 5 from the surface 8 facing the distribution pipe 3.
  • the holes 6 in the plate are arranged in several rows extending across the plate perpendicular to the direction of the pulp flow in the distribution pipe 3.
  • the recesses at the holes 6 in the surface 8 of the plate 5 facing the distribution pipe 3 are here achieved in that the surface 8 for each row of holes is provided with a groove extending across the plate 5 parallel to the row of holes and having the cross section described above and illustrated in FIG. 4.
  • the bottom of the groove i.e. the intersection between the two sides 12 and 14 of the groove is preferably slightly rounded, whereby the manufacturing as well as the cleaning of the grooves is simplified. This rounded bottom in the grooves is, however, not essential for the operation of the plate.
  • the holes in the different rows of holes are somewhat displaced relative to each other, whereby a more uniform distribution of the holes over the plate is obtained.
  • each hole 6 can, if preferred, extend all the way to the upstream edge 15 of the next hole.
  • a hole plate for distributing stock in a paper-making machine or the like comprising an elongated plate having a first lengthwise surface extending between a first end and a second end, means defining a plurality of holes extending through the plate substantially perpendicularly to the plane of the first surface for conveying stock through the plate, means defining a recess in the first surface adjacent each hole, each recess merging at one end into its adjacent hole at the edge of the hole nearest the said first end and having a base extending smoothly from the said nearest edge of the hole towards the said second end for a distance greater than the dimension of the hole lengthwise of the first surface and merging smoothly into the first surface at the other end of the recess, whereby the stagnation point of stock flowing over the first surface in a direction from the said first end to the said second end is located at a zone of the recess remote from the said nearest edge of the hole and whereby the stock is conveyed through the holes in a direction substantially perpendicular to the direction of flow of the stock over
  • each recess is substantially triangular in section taken on a plane perpendicular to the first surface of the plate and extending lengthwise through the plate, the apex of the triangular section being recessed below the first surface a distance not less than one-quarter of the said lengthwise dimension of the adjacent hole, the apex being located in the region of the adjacent hole, and the base of the recess between the ends thereof forming an angle with the first surface of the plate of not substantially greater than 30.
  • a hole plate according to claim 1 wherein the edge of each hole nearest the said first end of the plate is substantially coincident with the edge of the adjacent recess nearest the said first end of the plate.
  • a hole plate according to claim 1 wherein the holes are arranged on the plate in rows disposed transversely of the plate and the recesses are constituted by portions of continuous grooves in the plate extending parallel to the rows of holes.
  • a hole plate according to claim 10 wherein the holes are arranged in mutually parallel rows substantially perpendicular to the lengthwise extent of the plate.
  • a hole plate according to calim 10 wherein the holes are arranged in mutually parallel rows oblique to the lengthwise extent of the plate.

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US805106*A 1964-12-23 1969-02-27 Hole plate for one-sided inlet headboxes for paper machines Expired - Lifetime US3535203A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1561364 1964-12-23

Publications (1)

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US3535203A true US3535203A (en) 1970-10-20

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Application Number Title Priority Date Filing Date
US805106*A Expired - Lifetime US3535203A (en) 1964-12-23 1969-02-27 Hole plate for one-sided inlet headboxes for paper machines

Country Status (4)

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US (1) US3535203A (enrdf_load_stackoverflow)
FI (1) FI41341B (enrdf_load_stackoverflow)
GB (1) GB1069560A (enrdf_load_stackoverflow)
NO (1) NO132765C (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3962031A (en) * 1973-08-29 1976-06-08 Escher Wyss G.M.B.H. Stock inlet for a paper machine
US4016033A (en) * 1975-03-01 1977-04-05 J. M. Voith Gmbh Distribution means for aqueous slurry in papermaking machines
US4225386A (en) * 1978-03-23 1980-09-30 Aktiebolaget Karlstads Mekaniska Werkstad Headbox for a paper machine
US4455197A (en) * 1980-04-02 1984-06-19 Dominion Engineering Works Limited Stock supply system for paper machine
DE3400423A1 (de) * 1983-01-26 1984-07-26 A. Ahlström Oy, Noormarkku Siebplatte
DE3448571C2 (de) * 1983-01-26 1996-06-05 Cae Investments Bv Siebplatte für Fasersuspensionen
US5624558A (en) * 1994-08-04 1997-04-29 Cae Screenplates Inc. Method and apparatus for screening a fiber suspension

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3098787A (en) * 1960-07-21 1963-07-23 Time Inc Flow system
US3216892A (en) * 1962-04-12 1965-11-09 Karlstad Mekaniska Ab Headbox for paper machine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3098787A (en) * 1960-07-21 1963-07-23 Time Inc Flow system
US3216892A (en) * 1962-04-12 1965-11-09 Karlstad Mekaniska Ab Headbox for paper machine

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3962031A (en) * 1973-08-29 1976-06-08 Escher Wyss G.M.B.H. Stock inlet for a paper machine
US4016033A (en) * 1975-03-01 1977-04-05 J. M. Voith Gmbh Distribution means for aqueous slurry in papermaking machines
US4225386A (en) * 1978-03-23 1980-09-30 Aktiebolaget Karlstads Mekaniska Werkstad Headbox for a paper machine
US4455197A (en) * 1980-04-02 1984-06-19 Dominion Engineering Works Limited Stock supply system for paper machine
DE3400423A1 (de) * 1983-01-26 1984-07-26 A. Ahlström Oy, Noormarkku Siebplatte
JPS59137594A (ja) * 1983-01-26 1984-08-07 エ−．ア−ルストロム　オサキ−テイオ スクリ−ンプレ−ト
DE3448571C2 (de) * 1983-01-26 1996-06-05 Cae Investments Bv Siebplatte für Fasersuspensionen
DE3448571C3 (de) * 1983-01-26 2001-10-25 Cae Screenplates Oy Siebplatte für Fasersuspensionen
US5624558A (en) * 1994-08-04 1997-04-29 Cae Screenplates Inc. Method and apparatus for screening a fiber suspension

Also Published As

Publication number Publication date
GB1069560A (en) 1967-05-17
NO132765B (enrdf_load_stackoverflow) 1975-09-22
FI41341B (enrdf_load_stackoverflow) 1969-06-30
NO132765C (enrdf_load_stackoverflow) 1976-01-07

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