HEADBOX FOR PAPERMAKING MACHINE WITH MORE UNIFORM FLOW

CAISSE DE TETE POUR MACHINE A PAPIER, A ECOULEMENT PLUS UNIFORME

English Abstract

A headbox for a papermaking machine with an
outlet slot that distributes pulp suspension over the
working width of the papermaking machine. For
controlling operating parameters of throughput, pulp
density and fiber quality of the suspension over the
width of the machine, the headbox having a plurality of
individual sections across the width of the machine.
Each section has respective channels therethrough for
passing pulp suspension. At least one connection at
each section is to a controllable supply of pulp
suspension where the operating parameters of that
supply are controllable. Only separate operating
parameter controlled streams pass through the sections
of the headbox. Operating parameter control devices
may deliver adjusted streams to a mixer upstream of the
headbox channels. The mixer may also have individual
sections across the width of the machine. The headbox
has a common outlet nozzle downstream of the individual
channels and the individual sections, where the pulp
suspension stream from channels with controlled
suspension parameters and from any channels without
controlled suspension parameters are reconstituted to
have the desired suspension operating parameters.

Claims

-19-


CLAIMS
What is claimed is:

1. A headbox for a papermaking machine for distributing pulp suspension over
the working width of the papermaking machine, comprising:
(a) a pulp suspension guide having an upstream side, a downstream side and a
plurality of separate channels therethrough for conducting pulp suspension
from the
upstream side to the downstream side;
(b) a discharge nozzle including a discharge outlet, the nozzle being located
downstream of the downstream side of the pulp suspension guide, the discharge
nozzle being shaped such that the direction of flow of the pulp suspension
between
the downstream side of the pulp suspension guide and the discharge outlet as
viewed
from a side of the headbox remains essentially unchanged until down to the
discharge
outlet thereby to prevent mixing of the pulp suspension from the respective
channels
of the pulp suspension guide;
(c) means for adjusting the concentration of the pulp suspension over the
width of the
discharge outlet to produce a desired basis weight cross profile of a paper
web
produced, said adjusting means comprising:
flow means upstream of the pulp suspension guide having partitions dividing
the flow
means into a plurality of sections extending in the direction of flow of the
pulp
suspension and arranged side by side over the width of the papermaking
machine,
each section having at least two connections for the introduction of
respective streams
(Q_H, Q_L), at least one stream (Q_H, Q_L) of each section
having a
pulp concentration; at least one of the connections of each section including
means for
providing at least one of the respective streams (Q_H, Q_L) of that
section
with a predetermined throughput to adjust a ratio of the volumetric flows of
the
streams (Q_H, Q_L) of that section,



-20-


CLAIMS


in each section of the flow means the streams (Q_H, Q_L) are mixed to
form a
respective sectional mixed stream (Q_M) with a concentration (C_M)
which
depends on the ratio of the volumetric flows of the streams (Q_H,
Q_L), and
each section of the flow means feeding at least one of the channels of the
pulp
suspension guide with the respective sectional mixed stream (Q_M), and
means maintaining the sectional mixed stream (Q_M) of pulp suspension of
each
section at a volumetric flow that is a constant for the respective section of
the flow
means during the adjustment of the ratio of the volumetric flows of the
streams
(Q_H, Q_L), for maintaining a desired fiber orientation cross profile
in the
paper web produced.

2. The headbox of claim 1, wherein each of the streams (Q_H, Q_L) has
a
pulp concentration.

3. The headbox of claim 2, wherein the pulp concentration of at least one of
the
streams (Q_H, Q_L) is different than the other.

4. The headbox of claim 1, wherein each section of the flow means comprises a
mixer and a pulp guide section downstream of the mixer and upstream of the
pulp
suspension guide.

5. The headbox of claim 4, further comprising a respective mixer connection
for
each of the individual flow means sections, for individually setting the
operating
parameters for each of the sections.

6. The headbox of claim 5, further comprising suspension parameter control
means connected to the mixer connection, and including means for adjusting the
parameters.

7. The headbox of claim 6, wherein the parameter control means for the



-21-


CLAIMS


respective connection further comprises means for adjusting the concentration
of fiber
in the pulp suspension passing through the respective connection.

8. The headbox of claim 6, wherein there is a respective suspension parameter
control means connected with each of the two connections.

9. The headbox of claim 5, wherein the mixer also is divided by partitions
into
individual mixer sections over the width of the machine, and each of the
individual
mixer sections comprises means for delivering suspension to respective ones of
the
flow means sections.

10. The headbox of claim 5, wherein there are a plurality of the connections
between the flow means sections and the mixer at spaced apart locations across
the
machine width, and the mixer is undivided across the machine width, and the
undivided mixer communicates with the channels of the pulp suspension guide
through the flow means, such that the distribution of the connections to the
mixer
across the mixer delivers individually controlled suspension streams to the
individual
channels of the guide.

11. The headbox of claim 4, wherein the pulp guide section is partitioned into
sections across the width of the headbox.

12. The headbox of claim 11, wherein the pulp suspension guide sections are
formed by one of a perforated plate, a plurality of tubes, horizontal or
vertical plates
or flexible blades.

13. The headbox of claim 4, wherein connections between each mixer and the
pulp guide section comprise hoses or pipes.

14. The headbox of claim 4, wherein connections between each mixer and the
pulp guide section comprises an additional chamber partitioned into sections.



-22-


CLAIMS


15. The headbox of claim 14, wherein at least one of the mixer and the
additional
chamber sections have varying widths.

16. The headbox of claim 11, wherein the sections of the pulp guide section
have
varying widths.

17. The headbox of claim 1, wherein the flow means comprises a plurality of
mixers, the mixers arranged upstream of the sections of the flow means, each
mixer
feeding pulp suspension to one section.

18. The headbox of claim 1, wherein the flow means comprises at least one
mixer,
said mixer arranged upstream of the sections of the flow means and feeding
pulp
suspension to a plurality of said sections.

19. The headbox of claim 1, wherein the flow means comprises a plurality of
mixers arranged upstream of the sections of the flow means and said plurality
of
mixers feeding pulp suspension to one section.

20. A headbox for a papermaking machine for distributing pulp suspension over
the working width of the papermaking machine, comprising:
(a) a pulp suspension guide having an upstream side, a downstream side and a
plurality of separate channels therethrough for conducting pulp suspension
from the
upstream side to the downstream side;
(b) a discharge nozzle including a discharge outlet, the nozzle being located
downstream of the downstream side of the pulp suspension guide, the headbox
being
structured and arranged so that the direction of flow of the pulp suspension
between
the downstream side of the pulp suspension guide and the discharge outlet as
viewed
from a side of the headbox remains essentially unchanged until down to the
discharge
outlet thereby to prevent mixing of the pulp suspension from the respective
channels
of the pulp suspension guide;



-23-


CLAIMS



(c) means for adjusting the concentration of the pulp suspension over the
width of the
discharge outlet to produce a desired basis weight cross profile of a paper
web
produced, said adjusting means comprising:
a plurality of flow elements arranged upstream of the pulp suspension guide,
each
flow element provided with at least two connections for the introduction of
respective
streams (Q_H, Q_L) into the flow element to form a mixed stream
(Q_M)
with a concentration C_M in the flow element which concentration depends
on the
ratio of the volumetric flows of the streams (Q_H, Q_L), at least one
(Q_H,
Q_L) of each flow element stream having a pulp concentration, at least one
of the
connections of each flow element including means for providing a respective
stream
(Q_H, Q_L) with a predetermined throughput to adjust a ratio of the
volumetric flows of the streams (Q_H, Q_L) of each flow element,
each flow element feeding at least one of the channels of the pulp suspension
guide
with the respective mixed stream (Q_M), each flow element further
comprising an
outlet for discharging of the respective mixed stream into the pulp suspension
guide;
and
means maintaining the mixed stream (Q_M) of pulp suspension of each flow
element at a volumetric flow that is a constant for each flow element during
the
adjustment of the ratio of the volumetric flows of the streams (Q_H,
Q_L) for
maintaining a desired fiber orientation cross profile in the paper web
produced.

21. The headbox of claim 20, wherein each flow element comprises a mixer and a
pulp guide section downstream of the mixer and upstream of the pulp suspension
guide.

22. The headbox of claim 20, wherein each of the streams (Q_H, Q_L)
has
a pulp concentration.



-24-


CLAIMS


23. The headbox of claim 22, wherein the pulp concentration of at least one of
the
streams (Q_H, Q_L) is different than the other.

24. The headbox of claim 21, further comprising a respective mixer connection
for
each of the individual flow elements for individually setting the operating
parameters
for each of the elements.

25. The headbox of claim 24, further comprising suspension parameter control
means connected to the mixer connection, and including means for adjusting the
parameters.

26. The headbox of claim 25, wherein the parameter control means for the
respective connection further comprises means for adjusting the concentration
of fiber
in the pulp suspension passing through the respective connection.

27. The headbox of claim 25, wherein there is a respective suspension
parameter
control means connected with each of the two connections.

28. The headbox of claim 24, wherein the mixer is divided by partitions into
individual mixer sections over the width of the machine, and each of the
individual
mixer sections comprises means for delivering suspension to respective ones of
the
flow element.

29. The headbox of claim 24, wherein there are a plurality of the connections
between the flow elements and the mixer at spaced apart locations across the
machine
width, and the mixer is undivided across the machine width, and the undivided
mixer
communicates with the channels of the pulp suspension guide through the flow
elements, such that the distribution of the connections to the mixer across
the mixer
delivers individually controlled suspension streams to the individual channels
of the
guide.

30. The headbox of claim 21, wherein the pulp guide section is partitioned
into



-25-


CLAIMS


sections across the width of the headbox.

31. The headbox of claim 30, wherein the pulp suspension guide sections are
formed by one of a perforated plate, a plurality of tubes, horizontal or
vertical plates
or flexible blades.

32. The headbox of claim 21, wherein connections between each mixer and the
pulp guide section comprise hoses or pipes.

33. The headbox of claim 21, wherein connections between each mixer and the
pulp guide section comprises an additional chamber partitioned into sections.

34. The headbox of claim 33, wherein at least one of the mixer and the
additional
chamber sections have varying widths.

35. The headbox of claim 30, wherein the sections of the pulp guide section
have
varying widths.

36. The headbox of claim 20, wherein each flow element outlet feeds at least
one
of the channels of the pulp suspension guide with a mixed stream through a
respective
connection and wherein the connections between the respective outlets of the
flow
elements and the channels of the pulp suspension guide comprise tubes, pipes
or
hoses.

37. The headbox of claim 36, wherein each flow means comprises a mixer and a
pulp guide section downstream of the mixer and upstream of the pulp suspension
guide.

38. The headbox of claim 20, further comprising at least one of the at least
two
connections comprising a valve means.

39. The headbox of claim 36, further comprising at least one of the at least
two



-26-


CLAIMS

connections comprising a valve means.

40. A headbox for a papermaking machine for distributing pulp suspension over
the working width of the papermaking machine, comprising:
a pulp suspension guide having an upstream side, a downstream side and a
plurality of
separate channels therethrough for conducting pulp suspension from the
upstream side
to the downstream side;
a discharge nozzle, including a discharge outlet, the nozzle being located
downstream
of the downstream side of the pulp suspension guide, the headbox being
structured
and arranged so that the direction of flow of the pulp suspension between the
downstream side of the pulp suspension guide and the discharge outlet as
viewed
from a side of the headbox remains essentially unchanged until down to the
discharge
outlet thereby to prevent mixing of the pulp suspension from the respective
channels
of the pulp suspension guide; and
means for adjusting the concentration of the pulp suspension over the width of
the
discharge outlet to produce a desired basis weight cross profile of a paper
web
produced, said adjusting means comprising:
flow means arranged upstream of the pulp suspension guide, the flow means
having at
least two sections, at least one section provided with at least two
connections for the
introduction of respective streams (Q_H, Q_L), at least one stream
(Q_H,
Q_L) having a pulp concentration, at least one of the connections of the
at least
one section including means for providing at least one of the respective
streams
(Q_H, Q_L) of the at least one section with a predetermined throughput
to
adjust a ratio of the volumetric flows of the streams (Q_H, Q_L) of
the at least
one section,
in the at least one section of the flow means the streams (Q_H, Q_L)
are mixed
to form a mixed stream (Q_M) with a concentration (C_M) which depends
on



-27-


CLAIMS


the ratio of the volumetric flows of the streams (Q_H, Q_L), and
each section of the flow means feeding at least one of the channels of the
pulp
suspension guide, said at least one section feeding at least one of the
channels with the
mixed stream (Q_M), the flow means further comprising an outlet for
discharging
of the mixed stream into the pulp suspension guide, and
means maintaining the mixed stream (Q_M) of pulp suspension at a
volumetric
flow that is a constant during the adjustment of the ratio of the volumetric
flows of the
streams (Q_H, Q_L) for maintaining a desired fiber orientation cross
profile in
the paper web produced.

41. The headbox recited in claim 40, wherein said flow means comprises a mixer
and a pulp guide section downstream of the mixer and upstream of the pulp
suspension guide.

42. The headbox of claim 41, wherein the flow means comprises a plurality of
mixers, each having at least two connections for the introduction of
respective partial
pulp suspension streams, said plurality of mixers feeding respective mixed
streams
into a common pulp guide section downstream of the mixers and upstream of the
pulp
suspension guide.

43. The headbox of claim 40, wherein the flow means outlet further comprises
an
outlet from each section, the outlet from said at least one section being for
discharging
of the mixed stream from said at least one section, said outlet from the at
least one
section feeding at least one of the channels of the pulp suspension guide with
the
mixed stream, respective connections being provided between the outlets and
channels of the pulp suspension guide and wherein the connections between the
respective outlets of the sections of the flow means and the channels of the
pulp
suspension guide comprises tubes, pipes or hoses.

44. The headbox of claim 40, wherein each of the streams (Q_H, Q_L)
has



-28-


CLAIMS

a pulp concentration.

45. The headbox of claim 44, wherein the pulp concentration of at least one of
the
streams (Q_H, Q_L) is different than the other.

46. The headbox of claim 40, wherein the flow means has at least two sections
each having at least two connections for the introduction of said streams
(Q_H,
Q_L).

47. The headbox recited in claim 42, wherein said common pulp guide section is
divided into a plurality of separate compartments.

48. The headbox recited in claim 47, wherein a mixed stream from each mixer
feeds into a respective compartment of the pulp guide common section.

49. The headbox of claim 47, wherein a mixed stream from at least one mixer is
fed into a plurality of compartments of said pulp guide common section.

50. The headbox of claim 47, wherein a plurality of mixed streams from a
plurality of respective mixers are introduced into a single compartment of
said pulp
guide common section.

51. The headbox of claim 47, wherein each pulp stream in a compartment of the
pulp guide common section is introduced into a respective channel of the pulp
suspension guide.

52. The headbox of claim 47, wherein a pulp stream of a compartment of said
pulp guide common section is introduced into a plurality of channels of said
pulp
suspension guide.

53. The headbox of claim 47, wherein a plurality of partial streams from
plural
ones of said compartments of said pulp guide common section are introduced
into a



- 29 -

CLAIMS

single channel of said pulp suspension guide.

54. The headbox of claim 40, wherein the flow means is partitioned into a
plurality of sections and wherein each section of the flow means comprises a
mixer
and a pulp guide section downstream of the mixer and upstream of the pulp
suspension guide.

55. The headbox of claim 54, further comprising a respective mixer connection
for
each of the individual flow means sections, for individually setting the
operating
parameters for each of the sections.

56. The headbox of claim 55, further comprising suspension parameter control
means connected to the mixer connection, and including means for adjusting the
parameters.

57. The headbox of claim 56, Wherein the parameter control means for the
respective connection further comprises means for adjusting the concentration
of fiber
in the pulp suspension passing through the respective connection.

58. The headbox of claim 56, wherein there is a respective suspension
parameter
control means connected with each of the two connections.

59. The headbox of claim 55, wherein the mixer also is divided by partitions
into
individual mixer sections over the width of the machine, and each of the
individual
mixer sections comprises means for delivering suspension to respective ones of
the
flow means sections.

60. The headbox of claim 55, wherein there are a plurality of the connections
between the flow means sections and the mixer at spaced apart locations across
the
machine width, and the mixer is undivided across the machine width, and the
undivided mixer communicates with the channels of the pulp suspension guide
through the flow means, such that the distribution of the connections to the
mixer



-30-


across the mixer delivers individually controlled suspension streams to the
individual
channels of the guide.

61. The headbox of claim 60, wherein the pulp suspension guide sections are
formed by one of a perforated plate, a plurality of tubes, horizontal or
vertical plates
or flexible blades.

62. The headbox of claim 54, wherein connections between each mixer and the
pulp guide section comprise hoses or pipes.

63. The headbox of claim 54, wherein connections between each mixer and the
pulp guide section comprises an additional chamber partitioned into sections.

64. The headbox of claim 63, wherein at least one of the mixer and the
additional
chamber sections have varying widths.

65. The headbox of claim 60, wherein the sections of the pulp guide section
have
varying widths.

66. The headbox of claim 40, wherein the flow means is partitioned into a
plurality of sections and wherein the flow means comprises a plurality of
mixers, the
mixers arranged upstream of the sections of the flow means, each mixer feeding
pulp
suspension to a section.

67. The headbox of claim 40, wherein the flow means is partitioned into a
plurality of sections and wherein the flow means comprises at least one mixer,
said
mixer arranged upstream of the sections of the flow means and feeding pulp
suspension to a plurality of said sections.

68. The headbox of claim 40, wherein the flow means is partitioned into a
plurality of sections and wherein the flow means comprises a plurality of
mixers
arranged upstream of the sections of the flow means and said plurality of
mixers



- 31 -
CLAIMS

feeding pulp suspension to one section.

69. A headbox for a papermaking machine for distributing pulp suspension over
the working width of the papermaking machine, comprising:
(a) a pulp suspension guide having an upstream side, a downstream side and a
plurality of separate channels therethrough for conducting pulp suspension
from the
upstream side to the downstream side;
(b) a discharge nozzle including a discharge outlet, the nozzle being located
downstream of the downstream side of the pulp suspension guide,
(c) means for adjusting the concentration of the pulp suspension over the
width of the
discharge outlet to produce a desired basis weight cross profile of a paper
web
produced, said adjusting means comprising:
flow means upstream of the pulp suspension guide having partitions dividing
the flow
means into a plurality of sections extending in the direction of flow of the
pulp
suspension and arranged side by side over the width of the papermaking
machine,
each section having at least two connections for the introduction of
respective streams
(Q_H, Q_L), at least one stream (Q_H, Q_L) of each section
having a
pulp concentration; at least one of the connections of each section including
means for
providing at least one of the respective streams (Q_H, Q_L) of that
section
with a predetermined throughput to adjust a ratio of the volumetric flows of
the
streams (Q_H, Q_L) of that section,
in each section of the flow means the streams (Q_H, Q_L) are mixed to
form a
respective sectional mixed stream (Q_M) with a concentration (C_M)
which
depends on the ratio of the volumetric flows of the streams (Q_H,
Q_L), and
each section of the flow means feeding at least one of the channels of the
pulp



- 32 -

CLAIMS

suspension guide with the respective sectional mixed stream (Q_M), and
means maintaining the sectional mixed stream (Q_M) of pulp suspension of
each
section at a volumetric flow that is a constant for the respective section of
the flow
means during adjustment of the ratio of the volumetric flows of the streams
(Q_H,
Q_L) for maintaining a desired fiber orientation cross profile in the
paper web
produced.

70. The headbox of claim 69, wherein each of the streams (Q_H, Q_L)
has
a pulp concentration.

71. The headbox of claim 70, wherein the pulp concentration of at least one of
the
streams (Q_H, Q_L) is different than the other.

72. A headbox for a papermaking machine for distributing pulp suspension over
the working width of the papermaking machine, comprising:
a pulp suspension guide having an upstream side, a downstream side and a
plurality of
separate channels therethrough for conducting pulp suspension from the
upstream side
to the downstream side;
a discharge nozzle, including a discharge outlet, the nozzle being located
downstream
of the downstream side of the pulp suspension guide,
means for adjusting the concentration of the pulp suspension over the width of
the
discharge outlet to produce a desired basis weight cross profile of a paper
web
produced, said adjusting means comprising:
flow means arranged upstream of the pulp suspension guide, the flow means
having at
least two sections, at least one section provided with at least two
connections for the
introduction of respective streams (Q_H, Q_L), at least one stream
(Q_H,
Q_L) having a pulp concentration, at least one of the connections of the
at least



- 33 -

CLAIMS

one section including means for providing at least one of the respective
streams
(Q_H, Q_L) of the at least one section with a predetermined throughput
to
adjust a ratio of the volumetric flows of the streams (Q_H, Q_L) of
the at least
one section,
in the at least one section of the flow means the streams (Q_H, Q_L)
are mixed
to form a mixed stream (Q_M), with a concentration (C_M) which depends
on
the ratio of the volumetric flows of the streams (Q_H, Q_L), and
each section of the flow means feeding at least one of the channels of the
pulp
suspension guide, said at least one section feeding at least one of the
channels with the
mixed stream (Q_M), the flow means further comprising an outlet for
discharging
of the mixed stream into the channels of the pulp suspension guide, and
means maintaining the mixed stream (Q_M) of pulp suspension at a
volumetric
flow that is a constant during the adjustment of the ratio of the volumetric
flows of the
streams (Q_H, Q_L) for maintaining a desired fiber orientation cross
profile in
the paper web produced.

73. The headbox of claim 72, wherein each of the streams (Q_H, Q_L)
has
a pulp concentration.

74. The headbox of claim 73, wherein the pulp concentration of at least one of
the
streams (Q_H, Q_L) is different than the other.

75. The headbox of claim 72, wherein the flow means has at least two sections
each having at least two connections for the introduction of said streams
(Q_H,
Q_L).

76. A method for providing at least one of a selected basis weight cross
profile
and a selected fiber orientation cross profile over the width of a web of
paper being
manufactured in a paper making machine, wherein



- 34 -
CLAIMS

the machine includes a headbox having a plurality of separate suspension
supply
sections distributed along the width of the machine for supplying suspension
for
further processing into paper in the machine, and the machine further includes
means
following the headbox in the path of the suspension for processing the
suspension to
produce a paper web having a width along the width direction of the machine;
the method comprising:
supplying at least two partial streams to at least some of the sections of the
headbox,
wherein at least one of the partial streams to each of the headbox sections,
that is
being supplied by at least two partial streams, includes suspension, such that
each
section supplies a respective combined stream including suspension for further
processing;
selectively controlling the volume per unit of time of at least one of the
partial streams
to each of the sections, that is being supplied by at least two partial
streams, and also
selectively controlling the volume per unit time of the combined stream from
at least
one of the sections that is being supplied by at least two partial streams for
either
varying the basis weight cross profile of the web without affecting the fiber
orientation cross profile of the web, or varying the fiber orientation cross
profile of
the web without affecting the basis weight cross profile of the web, or
varying both of
the basis weight cross profile of the web and the fiber orientation cross
profile of the
web but with the variation of each such cross profile not affecting the other
such cross
profile; and further wherein the basis weight cross profile of the web is
varied without
affecting the fiber orientation cross profile of the web by adjusting the
partial streams
to each section for which the partial streams are adjusted in order to adjust
the basis
weight cross profile of the web, in a manner such that the total volume per
unit of
time of the combined stream supplied by each such section remains unchanged.

77. The method of claim 76, wherein the adjustment of partial streams to one
section for adjusting the basis weight cross profile comprises increasing the
volume
per unit of time of one partial stream to the one section while decreasing the
volume



- 35 -

CLAIMS

per unit of time of another partial stream to the one section.

78. The method of claim 76, wherein the fiber orientation cross profile of the
web
is varied without affecting the basis weight cross profile of the web by
adjusting the
volume per unit time of the combined stream to at least one of the sections
without
affecting the ratio of the volume per unit of time of the partial streams
forming the
combined stream to the at least one section.

79. The method of claim 78, wherein the volume per unit time of the partial
streams to the at least one section are selectively all increased or all
decreased to the
respective extents for maintaining the ratio of the volumes per unit of time
of the
partial streams to the at least one section constant and thereby maintaining
the basis
weight cross profile constant.

80. The method of claim 76, wherein the fiber orientation cross profile of the
web
is varied without affecting the basis weight cross profile of the web by
adjusting the
volume per unit of time of the flow from at least one of the sections without
affecting
the volume per unit of time of the flow from at least some of the other
sections and
without affecting the density of the suspension in the flow from any of the
sections
including the at least one section.

Description

2045038
- 1
HEAD$OX FOR PAF$RMAKINC~ MACHINE
WITH MORE UNIFORM FLOW
The present invention relates to a headbox
or breaatbox for a papermaking machine, and particular-
ly to means for adjusting the pulp density of the pulp
xuspen~ion over the working width of the headbOx or the
machine width.
One such hsedbox is known from Federal
Republic of Germany patent 35 14 554. Such a headbox
is fntended to make the pulp ~3uspenr3ion uniform over
the entire cross machine width of the pulp outlet from
the headbox. At the downstream end of the flow path of
the suspension, it should be made uniform in front of
the discharge or outlet slot from the headbox. The
uniformity sought is such that both the denstity of the
pulp. that is the weight of fiber content per unit
volume, and the oriunta~tion of the fibers in the pulp
ere constant over the width of the pulp outlet from the
headbox. Both of these qualities are important
prerequisites for the finished paper being produced by
the paperma~king machine, in order to have a proper
weight per unit area and a proper thicknea;~ profile
over the entire cross machine width of the web and so
that the paper lies flat and does not tend to curl.




2o~~oaa
_Z_
During operation of the pspermaking
machine, numerous disturbing factors interfere with the
satisfaction of the two uniformity requirements. Thence
factors include temperature variations, pressure
variations and manufacturing tolerances in the headbox
and in the pulp suspension, for example.
The above notad German patent is concerned
with s~olvinq tha same problems as are noted above,
which are also the problems to be solved by the present
invention, That patent recognizes that it is important
to both maintain the density of the fibers in the pulp
suspension over the width of the pulp outlet and also
to control the fiber orientation so that, if it is
possible, no transverse !low will occur iri the outlet
channel. The oerman patsnt proposes that the density
of the pulp suspension be changed locally, that is that
the density of the pulp suspension be changed at given
places across the machine width, as required. However,
the patent does not provide what is believed by the
present inventors to be the best solution to this
problem.
It is also known to vary the width of the
distcharge slot, that is the height of the outlet
open~.ng at the disGhar9e slot. One way to do that is
by tha use of threaded spindles for swingi»fl or bending
one lip, and partfcularly the upper lip that defines
the discharge slot. For instance, see Federal Republic
~f Germany patent 29 42 9s6 , corresponding to U.B.
Patent x,326,916, or Federal Republic of Germany
publi$hed Application OS 35 35 849. This adjustment of
the w$dth of the discharge slot enables local variation
of the throughput of the suspension, 11t the same time,




2045038
however, the direction of suspension flow is also
lOCally affected, which affects the orientation of the
fibers in the suspension. The local narrowing of the
outlet slot causes a different flow direction in the
fibers at the narrowed places of the slot than along
the remainder of the diaeharge slot. Although the
density of the pulp can be made uniform over the width
of the pulp outlet by the so-called displacement
control, the fibQr orientation, which may have been
la good, is undesirably again disturbed. Although the
inventors have recognized that the last two above noted
Germnn patent applications proceed fundamentally in the
correct direction, nonetheless, they do not appear to
be able to independently control the two parameters of
15 the density of the pulp and the fiber orientation.
it is an object of the invention to provide
a headbox or breastbox which enables independent
control of each of the parameters of the den$ity of the
~0 pulp suspension and the fiber orientation in the pulp
suspension in a practical and reliable manner.
The concept of the invention involves
sectionalizing the headbox into individual sections
across the machine width, which is an already known
25 design, and also to feed individually controllable,
partial streams or section streams of the pulp
suspension to the individual sections of the headbox.
The operating parameters of each individual one of the
parbiel streams, particularly their throughput, pulp
30 density and fiber quality, can be individually adjusted
without adjusting any of the parameters of the other




204508
- 4 -
partial streams or along with adjusting those
parameters in the other partial streams differently.
Each of the section streams feeds a respective separate
section of the headbox. Each of the section streams is
preferably conducted separately through the headbox,
and the streams are combined with each other only
toward the outlet nozzle from the headbox.
Each section stream is formed by bringing
together two separate streams for that section, of
which at least one stream in some embodiments, and in
other embodiments both streams have their above noted
parameters Controlled. Depending upon the mixture
ratio and pulp concentration and the flow rate of these
control streams, the nature of each of the section
streams in each individual section can be very
preaidely established.
The headbox of the present invention
distributes pulp xuspension over the working width of
the papermaking machine and ejects the suspension into
the inlet slot or nap of a web forming section, for
expmgle.
The headbox includes a pulp suspension
guide device through which peas a plurality of holes or
channels that define the channels and that extend from
the upstream to the downstream sides of the headbax.
The holes or channels are in a Selected array across
the width of the headbox. There is a discharge nozzle
also extending across the width of the machine with a
discharge or outlet slot for distributing the pulp
suspension.
Upstream of the headbox in the pulp
suspension flow path are located means far adjusting




2045038
the pulp density of the pulp suspension over the
working width of the machine. The individual BeCtions
of the haadbox are formed by partitions which divide
the headbox into individual separate sections over the
cro** machine width. Each individual section has at
least one feed line channel or hole for feeding through
!t a partial r~tream or section stream of the pulp
su*pen*ion.
A mixer is arxanged upstream of or in front
of the feed line of the headbox. In one embodiment,
the mixer has at least two connections for introducing
respective parameter controlled suspension streams,
having predetermined operating parameters, such as
throughput, pulp density and fiber quality. In other
embodiments, fewer than or only one of the connections
and its suspension stream i$ controlled. But through
merely that control, the final mixed output from the
discharge slot is controlled.
Other objects and features of the present
invention will become apparent form the following
de*cription of preferred embodiments of the invention
considered in connection with the accompanying
drawinq~~ in which:
gig, is schematically illustrates one pulp
sua~psnsion flow mixing apparatus, and shows means for
mixing flows that are supplied to individual sections
o~ the headbox;
his. 1b illustrates an alternate pulp
suspension flow mixting apparatu9;



2045038
-s-
Fig. 2a is a aide elevationai cross-
sectional view through one individual section of 8
B rat embodiment of a headbox, with a plurality of
individual pulp flow channels through it;
gig. ~b fs a plan cross-Sectional view of
the headbox of Fig. 2s showing individual, headbox
sections and showing a plurality of channels through
the haadbox arrayed across the width of the machine and
in each of the individual headbox sections~f
P'ig. 3a illustrates a second headbox
embodiment Like that in Fig. 2a and 2b and
schematically depicts the mixer which delivers
parameter controlled suspension to the headbox;
~'ig. 3b is an end view of the mixer of
Fiq. 3a, seen in the direction of arrow A in Fig. 3a,
showing individual deliveries of mixed suspension to
tht mixer for subseciuent delivery to the headbox;
Fig. 3c is a view in the same direction as
l~fg. 3b, showing a partitioned mixer embodiment for
individual deliveries of mixed suspension to the
headbox;
F'ig. 4a is a side elevational cross-
sectionol view through a third embodiment of ~ headbox,
where the individual sections are narrowed channels
a5 through the headbox and there arQ a plurality of thosQ
channels in each section, which are arrayed vertically
acroga the headbox;
Fig. 4b is a plan cross-sectional partial
view of the headbox of Fig. 4a showing the partitioned
headbox, showing the deliveries of different mixtures
of pulp suspension to the headbox and Showing the
individual channel sections arrayed across the machine
width


245038
Fig. ~c is an alternate fourth embodiment
Of the headbox and mixer of Fig. 4b, wherein the mixer
has individual partitioned sections, each for
transmitting to the headbox a respective mixture of
pulp suspension;
gig. Sa is a side elevational crosa-
seationnl view of a fifth embodiment of a haadbox and
mixer, showing two longitudinally spaced areas of
partial channel sactions~ in the headbox;
i~ig. Sb is a plan cross-sectional view of
the headbox of Fig. 3a, showing the individual sections
of the mixer across the width of the headbox;
Fig. 6a is a aide elevational cro~s-
sectional view of a sixth embodiment of a headbox and
mixer combination, wherein the mixer ist fed with a
premixed partial stream which is mixed with a
conventional supply of pulp suspen$ion;
Fig. 6b is an enlarged detail of P~iq. Gas
~'iQ. 6c is a rear view of the mixer of Fig.
6a, showing the suspension or material feed to the
mixer;
Fig. 7 i~c a side elevational cross-
sectionai view of a seventh embodiment of a headbox and
mixer combination where the mixed partial sttreams are
~5 fad into a channel between the tube bundles through the
haadbox;
his. 8a is a top view of an eighth
embodiment of a mixer and headbox combination wherein
the piuraiity of parameter controlled partial streams
are fed to connections acrossc the top of the headbox
past the introduction mixer;



204503
Fig. 8b i$ a top view of the headboa and
mixfr combination of Fig, 8a;
Fig. 9a is a side olevdtiona~l cross-
goctional view of a ninth embodiment of a combination
of headbox and mixer showing direct feeding of the
conneadtions across controlled partial stream into one
or more of the tube lines of the turbulence inserts of
a suction of the headbox=
f'ig. 9b is rear view of the headbox of Fig.
1.0 9a in the direction of arrow C in Fig. 9a;
Fig, 10a is a side elevational cross-
sectional view of an alternate, tenth embodiment of a
headbox with direct feed of a controlled mixture
partial stream into one or more of the tube lines;
Ffg, lOb i$ a plon longitudinal cross
section of the headbox and mixer of Fib, l0af
Fig, ila is a side elevational cross-
seationai, fragmentary, view of an eleventh embodiment
of a headbox showing feeding of the parameter
controlled mixtuxe into the nozzle space downstream of
the individual sections; and
Fig. lib is a top view of the headbox of
Fig. ila,
In the pulp su~xpens~ion control apparatus
shown in ~'ig, la, the mixer 20 delivers to the headbox,
not shown in xig. la, a mixed stream 22 having the
volume ~ and having the concentration CM of fiber
material in the pulp suspension.
3~ Th8 mixer 20 is supplied by two separate
pulp suspension streams which are brought together in




2fl45038
9 _
tha mixer. The first stream 2~ has the volume Qx and
the fiber concentration CH. The second stream 26 has
the volume QL and the fiber concentration CL.
The first pulp stream 24 is supplied from a
~tource, not shown, past the volumetric control,
adjustable valve 28 that is controlled by flow rate
controller 32. The second pulp str:am 26 is supplied
from another source, dnd it is mixed with a separate
pulp supply at the volumetric control, adjustable valve
1.0 34. The valve 3a is controlled by the flow rate
controller 36. That controller, in turn, is supplied
by the two liquid or suspension streams from the
scparote pulp sources 38 and 42 which are mixed in the
mixer at the controller 36. Adjustment of the valves
28 and 34 determines the volume ratios QH/QL. Also, by
appropriate control over special pulp sources 38 and
42, it is possible to adjust the concentration CL of
pulp suspension in pulp stream 26, therQby to adjust
the !low rate and the fiber concentration in conduit
22.
An actual situation controlled by the
control apparatus of Fig. la is now described. The
arrangement shown in Fig, la just delivers a pulp
su~tpansior, flow to a conduit 22 which i;~ connected to
2S ona of the individual sections of a headbox. As will
be apparent below, there may be an individual one of
the control apparatus shown in Fig. la for each of the
individual sections of the headbox across the machine
width, and each of those individual control apparatus
shown fn P'ig, la can be operated independently.
wring a periodic quality control check of
the paper web being produced or of the pulp $uspen$ion



2045038
-lo-
being dispensed by the headbox, it may be found that
the weight per unit area profile, at the individual
section across the width of the web, of the mixed pulp
suspension which is supplied through mixer 20 in Fig.
S la and controlled by the control devices shown in Fig.
la, differs beyond an acceptable level from a desirQd
value, either in flow volume QM or pulp ~euspansion
aoncentrntion CM. Therefore, the pulp density of the
suspension in the headbox must be suitably corrected at
this section across the width of the headbox.
According to the invention, the adjustment
can be made by varyfng the concentration CM of the
individual section stream 22 that is controlled by the
control apparatus shown in Fig. 1A. The necessary
change in CM, that is dCji, can be determined from a
previously prepared weight balance sheet. The
resulting corrected concentration C~ is dependent
exclusively upon the ratio of the control streamss
QH/QL. The fiowthrough of theca two streams may be
halted while the ratio adjustment is made. The
corrected value of CM is used as a basis far ratio
control to establish the dasir~ad value setting. The
ratio control eats the new controi/flow ratio Q~/CM,
in Fig. 1A this is accomplished by changing QL, e.g.
through valve 34 and through sources 3a and ~2.
~towevar, it ia~ important that the combined volumetric
flow Q~ remain constant, so that the individual headbox
section may be fed with a correct consttant volume.
Therefore, to correct the volume and Concentration, the
control volume stream QH is corrected in accordance
with a production continuity equation which had
previously been prepared. This control is carried out



2045038
- 11 -
using the apparatus Shawn in Fig. la. For this purpose
the change in the desired value of the Control volume
streams must be calculated from new concentration C~
and must then fed to the controllers effective for
bringing this about at 28, 3a, and 36. Various types
of flow controllers for dQlivery of pulp suspension at
the oorrsct concentration may be used, as is known to
one Skilled in the art.
Transverse flows of the suspension can take
place within the headbox and in the headbox ~tpray
nosile. These could result, for ext~mple, due to rage
influences in the headbox. Thins can lead to an
undeetired affect on the orientation of the fibers in
the suspension. In known headboxes, this occurss
because of the presence of different volumetric streams
over the Gross machine width of the headbox.
Due to the flow control, apparatus of
gig, la, the concentration of fibers in the suspension
C~ remains constant. The calculated required
volumetric stream of QH is fed as a desired value to
tho controllers. This adjusts the two streams until
the desired volume QM and concentration CM are present
in the ~ctream 22.
in accordance with the alternate Control
apparatus shown in Fig, 1b, the tame types of
oparations~ take place and similar element~t are present,
except that both of the streams Qx and QL ar~
controlled by the adjustable valves 32 and 36 which
correspond in function to the valve 28. The other
element~c in Fig. 1b which correspond to thoste in Fig.
la are similarly numbered. In the apparatus of Fig.
1b, two calculated volumetric streams QH and QL must be


2045038
_ 1~ _
fAd ast new desired values to the controllers, In Fig.
la, in Contrast, it is possible to operate on a single
stream QH to obtain the desirsd value.
The present invention may be applied to
various types of headboxes, including single layer
headbox, multiple layer headboxes, headboxe;s for slit
formats, paper wires, with and without vibration
dampers, having one or two tube bundles, etc.
Various headbox and mixer embodiments are
shown in pigs. 2-11 and are now briefly described.
Figrs. 2a and 2b illustrate a headbox having
individual mixed suspension streams 22 at QM CM
delivered to the headbox. In Fig. 2a, the headbox has
an entrance section S2 from the mixer (not shown here),
1b individual section channels 54 in a vArtical stack,
which are defined by partitions between them, and a
tapering outlet noazle 56 leading to the outlet slot 56
from which the stream 6~, Still at total volumA QM and
concentration CM, is sprayed into an inlet nip, onto a
wire former, etc., in the usual manner for headboxes.
gig. 2b shows that there are individual
streams QM, CM across the width of the machine. Each
stream may be supplied by a separate control
arrangement ass in hig, la or Fig, 1b. The headbox
entrance section is divided into individual aeation~
52a, 82b, e~tc., across the width of the machine. Each
of the entrnnce sections is an inlet which feeds a
respective plurality of individual channels 54, which,
ag can be keen from both of Figs. 2a end 2b, arA
arrayed in rows and columns within the headbox. The
channels 54 are in partitioned sections 85a, 55b, 55x,
etc. in the headbox. There is a single combined outlet




~0450~8
- 13 -
nozzle 56 through which the various flows from the
channels 54 mix and then exit tho headbux. It iS
apparent that control over the individual volumes QM
and concentrations of pulp or fiber CM will control the
respective flows through the individual partitioned
channels of the partitioned sections 55s, 55b, 55x, for
providing a desired uniformity of flow volume and
aoncentretion across the width.
Figs. 3n, 3b and 3c show a headbox '70 with
to a plura~iity of individual partial sections 54 which are
aceparated by individual partitions and supplied by a
common mixer 20.
As can be sseen in ~'ig. 3b, the mixer 20
itself might not have individual sections, but its
partitioned design would permit some mixing of the
suspension passing through the mixer before it reaches
the individual sections, like sections: 55, of the
headbox, tn Zrig. 3c, in contrast, the mixer 74 also
has individual sections 768, 76b, etc., each
corresponding to and for delivering mixed suspenstion to
respective individual sections 55 of the headbox.
Figs. 4a and 4b show an alternate headbox
dessign 80 from th8t shown in Fig9. 2 and 3, wherein
there is a unitary and not individually sectioned
a5 entrance portion B1 to the hse~dbox, followed by
individual separated channels or tubes 82 through the
headbox which are arrayed in vertically spaced apart
stacl~e end horizontal7.y spaced apart columns. This
providea~ individual sections across both the height and
the width of the headbox. Each section across the
width of the headbox is supplied generally from its own
respective adjusted suspension stream ~~, CM. There is




245038
4_
an outlet no:zie 83 from the hGadbox where the various
flows through the channels 87 nre recombined.
l~ig. 4c differs from Fiq. 4b only in that
the mntry suction $4 of the headbox 86 itself has
individual vertical partitions dividing the entry
section 84 into individual sections 88a, 88b, etc.,
corresponding to one or more of the individual channels
82. Some of the chambers 88 may supply more than one
of the individual channels 82, as suggested in Fig. 4c.
Figs. 5a and Sb show an alternate headbox
90 Which has an entry chamber area 92 with panels 94
that separate the entry chamber into separate sections
92a~, 92b, etc. Downstream of the sections 92a are
narrowed channels 96, which in turn lead into a common
1b transmitting chamber 98 and that leads to the
individual section channels 102 which correspond in
function and placement to the channels shown in F19.
4a. Following the channels 102 downstream is the
outlet nozzle 104. The individual channels 96 are more
frequent than the downstream channels 102.
Figs. 6a, 6b and 6c illustrate a headbox
110 and a mixer 112 which cooperate. The headbox
includes a plurality of individual arose machine
sections i13, as in previous embodiments. each section
2S hays at least one column and more likely n plurality of
verbfcally arrayed columns of tubes or channels 114.
~n outlet nossie 116 follows all of the channels 114
downstream. The mixer 112 is at and delivers
suspension streams QM C~ to the inlet ends of the
passages llQr in the headbox.
Figs. 6a and bb show inlet through the
first inlet passage lib of only part of the total flow




2045038
to the mixer from a control apparatus as in Fig. la or
1b. A separate stream is delivered to the mixer
through the pa~asageway 7.20 from a conventional ~tource
122. Therefore the mixer 112 mines the concentration
adjusted and volume adjusted stream QM CM and the
conventionnl additional stream. Fig. 6c s~howa the
mixer 112 as not having partitions dividing it in the
cross machine direction. But the mixer 112 could
additionally be supplied with partitions like the mixer
74 in F'ig. 3c.
Fig. 7 shows the feeding of the adjusted
quantity and concentration mixture ~M, ~ into the
mixer 130 through the inlet port 131. ,rust its in the
embodiment of rigs. 6a, 6b and 6c, the partial stream
QM, CM is only part of the liquid supplied to the
hesdbox. A conventional uncontrolled stream of pulp
suspension or liquid is delivered to the mixer 130 from
the conventional suspension source 132 thrpugh the
passages 133.
Then the mixer delivers the mixed
su~tpension to the headbox 134 which has ateparated upper
and lower tube bundles or channels 135, 136 which in
turn deliver a~u~xpension streams to bs mixed in the
nozzle 138. The feeding of the mixed partial stream
2S QM, CM its into a channel between the tube bundlest 135,
136, and the tube bundles may, for example, ba defined
by oppropriate perforated plates.
Digs. 8a and 8b show another mixer and
headbox arrangement. The bandbox 140 has the separate
section inlet part 142 which receives only a first
liquid stream, e.g., a first controlled adjusted stream
or a conventional pulp suspension stream. This is

2045038
-ls-
supplied across the width and height of the headbox by
the di~ntributar 143. Downstream of the inlet part 142
is a common entrance section 144 into and across the
top of which all of the individually adjusted volume
and concentration flows Q~, CM from apparatus as in
~Fi9r, la or lb are introduced through respectiwa ports
lab arrayed across the machine width. The section ld4
is followed by the individual channels or tubes, which
define the headbox sections 152. That is followed by
the noZxie 154, asp in the other embodiments.
Figg. 9a and 9b show an alternate
arrangement with a headbox 160 having individual
channels or tube bundles 162, 164 above one another.
l~n entry mixer device 166 delivers pulp suspension from
a conventional source 168 through passages 169. The
controlled volume and concentration flow QM, CM is
directly fed into the section channels or tubes 164
without also being fed into the channels or tubes 162,
while the conventional flow is !ad into the tubes 162,
2Q but not into the tubes 164. The two flows are
therefore separated in their passage through the
individual sections of the headbox, but the flows are
joined in the nozzle 167 and they exit mixed together
through that nozzle outlet 170. From Fig. 9b, it can be
seen that the common conventional source 168 feeds
liquid not in a common flow but rather in long
individual separated tubes 169 across the width of and
through the intermediate section 174 and into the top
part of the mixer 166 before that liquid is delivered
distributed across the headbox to the tubes 162.
Fig. l0a shows an alternate headbox design
180 with a supply of suspension by a conventional


204038
supply 182 at its entrance through the tube section 184
and into the common entry area 186. The liquid
suspension at controlled volume and concentration gM ~ t
is~ fad through the tubes or channels 188 into the
no:gle 192. The Conventional liquid leaves the
intermediate chamber 186 and passes through the tubes
19~. The separated flow through the tubes 188 and 194
is mixed together in the nozzle 192, like in the
embodiment of Figs. 9a and 9b.
Finally, Figs, lla and llb show a headbax
200 having a separated flow, in individual sections in
tht form of 202 in the entry section 204 of
conventional pulp suspension. The controlled flow QM,
cM for the individual sections is delivered through the
entrance candufts 206 arrayed across the machine width
is the outlet and mixing nozzle 208, which !g
downstream from the individual sections 202 through
which the conventional suspension travels. The
distribution of the individual entrance ports 206
across the width provides the individual sections of
the headbox with needed concentration adju~3tment.
In all cases, the flow which has been
adjusted across the width of the headbox is
reconstituted as a single, corrected concentration and
orientation fiber flow in the downstream nozzle before
it exits through the discharge outlet.
With respect to some of the above described
embodiments, two controlled streams are used. tn
others, there is a mixed partial flaw from a
conventional source and from the controlled flow QM,
CM, which are fed through the headbox entrance section.
The entrance section is developed so that the two



2045038
~le-
streams mix. In that case, the mixer could bo located
directly within the headbox.
Although the present invention has been
described in relation to particular embodiments
thereof, many other vt~riations 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 spQCific diselosture
heroin, but only by the appended Claims.

Representative Drawing