Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a device for controlling mutual
arrangement of wires in a paper making machine or in a cardboard making
machine .
More specifically, the device relates to the controlling of wires in a
twin-wire section where the wires run parallel, one above the other, and where
stock is introduced between the wires to be dewatered. There is usually a
dewatering box above the upper wire, partial vacuum prevailing in said
dewatering box in order to draw up water that has been expressed from the
stock. Under the lower wire is provided a supporting table or equivalent,
which is fixed relative to the dewatering box.
It is desirable, and necessary, in machines of this kind to be able to
change, on one hand, ~he thickness of the dewatering gap defined between the
wires and, on the other hand, the configuration of said gap in the longitudinal
direction of the machine.
To this purpose there are controlling members adapted to urge the lower
wire upwards in a direction against the upper wire, which in its turn lies against
the dewatering box.
It is thus understood that said controlling members act between the
supporting table and the lower wire.
In Swedish Patent No. 8501985-9 and in its German equivalent No.
3,406,217 a wire controlling track is disclosed wherein is provided a number
of strips positioned closely side by side and extending laterally across the wire
width, said strips Iying against the lower wire and the pressure of said strips
against the lower wire being adjustable. The strips are displaceable towards
the lower wire and away therefrom, but the angle of the top~ surfaces of said
strips against the wire plane is not adjustable.
The problem solution described in the Swedish Patent No. 8501985-9
is furthermore encumbered by the drawback that the strips lie close together.
This has the effect that the strips act frictionally engage each other, and proper
control is therefore impeded. The strips tend to assume oblique position so
that their top surfaces are not fully parallel to the plane of the wires, owing to
friction against the lower wire. Moreover, liquid cannot escape downward
unless the strips are designed to have suction slits or equivalent.
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In German Patent No. 3,153,305 another wire controlling track is
disclosed wherein a number of mutually spaced strips are present, Iying against
the lower wire. These strips are individually regulated as regards their pressure
against the lower wire, with the aid of a spring member. However, each strip
is pivotally connected with the spring member coordinated with the particular
strip, and therefore the position of the top surface of the strips relative to the
horizontal plane cannot be adjusted. Thus, according to this patent,
t compensation of inclined position of the strips' top surfaces relative to the
surface of the lower wire, owing to friction between the lower wire and the
strips, cannot be achieved.
Thus, various attempts are known to adjust the pressure against the
wire, and thereby against the stock.
It has been discovered that, in order to attain optimum functioning
re~arding dewatering of stock in a twin-wire section, it is essential that the
pressure against the forward end of the strips, as viewed in the longitudinal
direction of run of the machine, and that against the rear end, thereof be
separately adjustable.
This enables any desired pressure profile to be set up over each strip.
Furthermore, the inclined positioning mentioned above can be eliminated.
The present invention provides device by the aid of which it becomes
possible to achieve what has just been said.
Furthermore, the construction of the device is simple and sturdy.
In general terms, the present invention provides a device for controlling
mutual arrangement of wires of a dewatering gap in a twin-wire section of a
paper or cardboard making machine in which machine the wires are adapted
to run through the gap in a longitudinal direction one over the other to dewaterstock present in said gap;
a dewatering box being provided exteriorly of the gap, along and in contact
with one of the wires;
a number of lateral strips being disposed exteriorly of the gap in a side by side
arrangement, the strips having each a top surface disposed along and in
contact with the other one of the wires, the strips extending over the
entire width of said wires;
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the strips being operatively associated with pressure elements arranged to
pressed the strips against said other wire in a direction toward said
dewatering box;
said pressure elements being disposed to act between the strips and a
supporting table or an equivalent thereof, the said table being fixedly
mounted relative to said dewatering box;
a separate pressure element being provided for each strip and comprising at
least two force-applying members disposed between the respective strip
and the supporting table;
a first one of the at least two force-applying members being disposed to act
against a forward end of the respective strip as viewed in said
longitudinal direction;
a second one of the force-applying members being disposed to act against a
rear end of the strip as viewed in said longitudinal direction, the force-
applying members being individually controllable;
whereby both the pressure of the respective strip against the respective wire
and the angle of the top surface of the respective strip relative to the
wire can be selectively adjusted.
The invention will now be described in detail by way of preferred
embodiments, with reference to the attached, simplified, diagrammatic
drawings. In the drawings:
Fig. 1 shows a sectional view of a twin-wire section of a paper making
machine where the present invention is applied, the section being taken
on a plane generally vertical and parallel with the longitudinal direction
of the machine which, of course, coincides with the movement of the
wires through the gap;
Fig. 2 shows, on larger scale, one strip and ancillary control members
according to the invention, in section conforming to Fig. 1;
Fig. 3 shows, on an even larger scale, the portion of said control member
which is on the left in Fig. 2;
Fig. 4 shows a first alternative embodiment of the control member, in a section
corresponding to that of Fig. 1;
Fig. 5 shows a second alternative embodiment of the control member, in a
section conforming to the section in Fig. 1; and
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Figs. 6 and 7 show further embodiments of force-applying members, the
figures being schematic sections taken in a vertical plane corresponding
to the section A-A in Fig. 2.
In Fig. 1 an elevational view is shown of a twin-wire section 1 of a paper
machine, where the upper wire 2 runs over deflection rolls 3, 4, 5 and 6 and
where the lower wire 7 runs substantially parallel with and under the
lowermost run of the upper wire 2. The wires 2,7 define dewatering gap
which includes a wedge-shaped entrance portion 8, where the stock is
successively compressed. The longitudinal direction of the machine and of the
run of the wires 2,7 through the gap is designated with an arrow 9. In Fig. 1
are also shown a multitude of set-up members, which are of a king known in
the art and which therefore are not more closely described.
Proceeding in the longitudinal direction 9, and after said wedge-shaped
entrance portion 8, the gap further includes a dewatering run, comprising a
dewatering or suction box 10 containing three chambers 1, ll and lll, which are
arranged to operate at different degrees of vacuum. Water from the stock is
drawn up by ducts 11 into the chambers. The ducts 11 are included in the
bottom 12 of the dewatering box 10. The upper wire 2 runs against this
bottom.
Under the lower wire is provided a supporting table 13, mounted fixedly
relative to the dewatering box 10, this table being carried on a stand generallydenoted with reference numeral 14.
Upon the supporting table 13 is provided a control member in the shape
of a number of pressure elements 15 arranged to press transverse or lateral
strips 16 (Fig. 2) upward in Fig. 1 to apply pressure against the lower wire 7,
and thus against the stock in the gap.
These pressure elements 15, one of which is shown on a larger scale in
Fig. 2, are thus placed between the underside of the strips 16 and the
supporting table 13. As has been mentioned, the top surfaces of the strips
have been disposed to lie against the lower wire 7.
The strips 16 are provided with grooves 18 for carrying off water from
the stock.
According to the present invention, a separate pressure element 15 has
been provided for each strip 16, each pressure element comprising at least two
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force-applying members 19,20;21,22;23,24, between the respective strip
16,31,32 and the supporting table 13. The members 19-24 are disposed to
displace the strips in the direction toward and away from the dewatering box
10. A first one of the members 19;21;23 is disposed to act against the
5 forward end 25;26;27 of the respective strip 16,31,32 as viewed in the
longitudinal direction 9 of the run of the machine, and a second one of the
members 20;22;24, to act against the rear end 28;29;30 of the strip as
t viewed in the same direction.
Furthermore, the force-applying members 19-24 are individually
10 controllable so that, on one hand, the pressure of the strip against the lower
wire, and, on the other hand, the angle of the top surface of the strip with
reference to the lower wire, can be adjusted.
According to a preferred embodiment, the strips 16,31,32 are placed
parallel with and spaced from one another. The distance between the strips
15 amounts only to a fraction of the width of one strip.
Thus, the strips cannot affect each other by frictionally engaging each
other or by abutting together, which would be the case if the strips were
placed very close to each other. If such interference were to occur, the
individual adjustment of the strips would be impeded.
The present invention therefore results in every strip being individually
adjustable so that optimum control of the controlling track in the twin-wire
section can be obtained.
According to a specifically preferred embodiment of the invention, the
force-applying members comprise rubber bellows or equivalent, arranged to be
controlled with the aid of compressed air.
In Fig. 2 is shown a first embodiment of the invention, corresponding to
the embodiment depicted in Fig. 1.
According to this embodiment, the supporting table comprises a
supporting heel 33, mounted on the carrying frame 34 of the supporting table
30 13.
According to the embodiment depicted in Fig. 2, each one of the force-
applying members consists of a rubber bellows 19,20, where the two bellows
19,20, seen in the transverse are wedge-shaped and are placed against and
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upon each other so that together they constitute a substantially rectangular
pillow between the strip 16 and the supporting table 13.
The rubber bellows are preferably made of fabric-reinforced rubber, or
of material having equivalent properties.
Between the sides 35,36 of the bellows 19,20 which face each other
is provided a fixing element 37 in the shape of a plate. One end portion 38 of
the fixing element is fixedly secured to the supporting table 13(33), and the
t other end portion 39 of the fixing element is integrally connected with the strip
16.
In Fig. 3, the securement on the left in Fig. 2 is shown on an enlarged
scale. Fig. 3 also shows the left margin of the lower bellows 20 fixed in place
with a threaded joint to the supporting table. The reference numeral 40
indicates a clamp of plastic or metal and numeral 41, a screw.
The fixing element may likewise be made of fabric-reinforced rubber, but
it may also be made of sheet metal.
In Fig.2, broken lines schematically indicate nipples 42,42' for inlet and
discharge of compressed air to the bellows 19,20. The nipples are preferably
placed on the respective end of the bellows.
It is obvious that if compressed air is introduced in the bellows 19 up to
the pressure higher in bellows 19 than in bellows 20, the left (forward) end of
the strip 19, its forward end will be raised more than its right-hand (rear) end.
This is illustrated by the interrupted line 43 in Fig. 2.
Suitably, the surfaces of the bellows adjoining the underside surface of
the strip 16 and the top surface of the supporting heel 33 have been affixed
to the respective surface. This may be done with mechanical fasteners or by
cementing the bellows to the respective surface.
In Figs. 4 and 5, other alternative preferred embodiments are shown.
According to these embodiments, the strip 31 ;33, and the supporting
table 44;45, partly embrace each other so that the strip 31;32 has only a
limited mobility relative to the supporting table 44;45. Due to this embodiment
there is no need for any fixing element of the type just described in connectionwith Fig. 2.
According to the embodiment depicted in Fig. 4, a further bellows 46
has been provided which holds within itself the two bellows 21 and 22 already
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mentioned. These inner bellows 21,22 are fixed to the outer bellows 46,
which in turn is secured to the strip 31, or to the supporting table 44, by
means of mechanical fasteners or by cementing.
A duct for introduction and evacuation of compressed air is provided for
5 each inner bellows 21,22.
As can be seen in Fig.4, the strip is restrictedly displaceable over a very
short distance in the left/right direction in Fig.4. The strip is further restrictedly
,, displaceable upward/downward in Fig. 4, over a longer distance than in the
lef:/right direction. Actually, there is no desire to make the strip displaceable
10 in the left/right direction: the free play which is present between the strip and
the supporting table is merely to facilitate the upward/downward displacement
and inclined positioning of the top surface of the strip.
A duct 49 between the outer bellows and free atmosphere must be
provided. As an alternative, the ends of the outer bellows may be open.
In Fig. 5 is shown an embodiment equivalent to that of Fig. 4, featuring
two bellows 23,24 fixed in a support 50,51, for the strip 32, and a portion 45
belonging to the supporting table.
According to this embodiment, too, the strip is restrictedly displaceable
relative to the supporting table. Ducts 52,53 have been provided for inlet and
discharge of compressed air.
According to the embodiments described in connection with Figs. 4 and
5 as well, the bellows 21, 22,46,23,24 are preferably made of a fabric-
reinforced rubber material.
The strips are made of a suitable wear-resistant material.
According to the embodiment, shown in Fig. 6, every rubber bellows 19
has a length generally corresponding to the total length of the respective strip16. However, according to another embodiment one bellows or both bellows
carrying a strip 16 may consist of two or more bellows 19',19",19"' located
after each other in a transverse row, so that the bellows 19',19",19"' in
combination constitute a force-applying member having a length generally
equal to the total length of the respective strip 16, see Fig. 7. In that case,
every bellows 19',19",19"' is provided with a nipple for inlet and discharge
of compressed air. Each bellows 19',19'',19''' is individually adjustable.
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This embodiment implies that it is even possible to control the pressure
profile across the width of the wire 7.
According to a further alternative embodiment, a long bellows extending
over the entire width of the wire may be subdivided into different sections.
In the foregoing various exemplifying embodiments have been described.
It is obvious that the bellows may have other shapes and cover a greater or
smaller part of the underside of the strips and of the top surface of the
supporting table as seen in section according to Figs. 2, 3 and 4. Furthermore,
the bellows may be made of elastomeric materials other than those mentioned
in the foregoing and which are suitable in the application in hand.
It goes without saying that the strips may also be of other embodiments,
as may the supporting table. Furthermore, the fixing element 37 may
constitute a spring element in case it is made of metal.
Thus, it is to be appreciated that the present invention is not to be
considered confined to the embodiments presented in the foregoing. We
therefore wish to protect by Letters Patent which may issue on the present
application all such embodiments which fall within the scope of our
contribution to the art.
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