Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1(~88789
This invention relates to improvements to means that
provide a seal for the covers of suction boxes in papermaking
machines, and to covers of suction boxes that include these
improvements.
More particularly, the invention concerns improve-
ments to means that provide a seal for the covers consisting
in making this seal with blocks of an elastic material which
can be positioned as wanted along the suction channels bounded
by the dewatering foils that compose the covers; and means are
provided to position and means to clamp said blocks.
The application of suction boxes to papermaking
machines is known whereby these suction boxes are placed below
the belt conveying the paper pulp and are equipped to remove
the water from the pulp.
Suction boxes of the known types are provided with
a cover consisting of dewatering foils spaced apart and
positioned crosswise to the conveyor belt, whereby the foils
form between themselves some crosswise suction channels through
which the water extracted from the paper pulp falls.
It is known that, when the width of the conveyor belt
or of the part thereof covered by the pulp varies, it is
necessary to adjust the length of the suction channels by
moving along them the sealing means placed at their ends.
The known means that provide the seal consist of -~
combs which can be positioned and are connected to the bottom
of the suction boxes and which, protruding upwards therefrom,
lodge themselves in the suction channels of the cover of the
suction box.
The comb-type sealing means involve various drawbacks
and disadvantages.
One drawback is that every time the dewatering foils
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or the whole cover are replaced, the teeth of the comb have
to be adapted to the individual channels; this shortcoming
is specially noticeable where the covers are supplied with the
foils already installed, as is the modern practice.
Another drawback is that the combs cannot realize
a perfect lateral seal in said channels because they have to
move along the channels.
A further drawback is that the continual adjustments
made to the combs when dewatering foils are replaced increases
the play between the combs and the foils and thereby lessens
the effectiveness of the seal. - -
Alongside these drawbacks, the comb-type sealing
means involve the disadvantage that they cannot be readily
positioned and are hard to make. -
An object of this invention is to provide sealing
means which are not connected to the suction box but are
installed directly on the covers thereof.
Another object is to provide sealing means which are
suitable for ensuring a perfect seal against the dewatering
foils and are equipped with positioning means and clamping
means that are easy to make and use.
A further object is to provide sealing means made of ~ -
a material which can be deformed and is suitable for being
adapted to fit the shape of the suction channel.
Alongside these objects, the invention provides the
advantage that it can be readily made and can be supplied
together with the cover of the suction box or as an individual
part. Moreover, the invention embodies the advantage that it
can be positioned in a channel between two foils independently
of the sealing means in the other channels of the cover.
Said obiects and advantages together with other ~ -
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objects and advantages which will become evident in the
description given hereinafter are pursued by this invention
with improvements to means that provide a seal for the covers
of suction boxes in papermaking machines, the covers consisting
S of dewatering foils spaced apart and positioned on a supporting
structure, the foils forming between themselves suction
channels lying crosswise to the belt conveying the pulp, said
improvements being characterized by the fact that the sealing
means consist of blocks which can be deformed and positioned
as wished in the suction channels of the covers; also means
are provided to position and to clamp the blocks.
So as to show the features of the invention more
clearly, we give hereinafter, as a non-limiting example, the
description of a realization of the invention, at the same
time referring to the attached table, wherein:
Figure 1 is a perspective view of part of a cover of
a suction box provided with improved sealing means according
to the present invention;
Figure 2 is a lengthwise section along one of the
sealing means of Fig. l; and
Figure 3 is a three-quarter view of one of the
sealing means of Fig. 1.
With reference to the figures, wherein the same parts
or parts performing the same functions bear the same reference
numbers: 10 is generically the cover for suction boxes in
papermaking machines and 110 is its end; 11 is the supporting
structure of the cover 10 and consists in, the present
embodiment, of lengthwise bars 12 and crosswise angle irons 13;
14 are generically the dewatering foils spaced apart and
positioned on the upper side 16 of the structure 11 of the
cover 10, the dewatering foils have advantageously at least
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their leading edge, which cooperates with the belt conveying
the paper pulp (this belt is not shown here), made of a hard,
wear-resistant material; 15 are the suction channels and
are bounded at their sides by the dewatering foils 14 and at
their ends at the extremity 110 of the cover 10 by the means
providing the seal 18; 16 is the upper side of the cover 10
on which the belt (not shown here) conveying the pulp slides,
while 17 is the lower side where the suction box (also not
shown in the figure) is positioned; 18 are generically the
means providing the seal and consist of blocks lodged in the
suction channels 15; 19 is the part or element of the blocks
18 which is made of a material that can be deformed, being
advantageously made of rubber, elastic polyurethane or an -. .
elastic resin that can be deformed; the sides 28 of said part
that can be deformed 19 are substantially shaped like the
lateral profile of the dewatering foils 14 and cooperate
therewith, being shaped in the present embodiment with a ledge
29; 20 are generically the means containing the faces of the
part which can be deformed 19 and cooperate with the means
clamping the bloclc 23, consisting in this embodiment of a -front outer plate 21 and a rear outer plate 22, both of which
extend as far as the faces of part 19 and are shaped like them;
23 are the means clamping the block 18 and consist in this
example of a threaded bolt which passes inside the part that
can be deformed 19 and links together the outer plates 21 and .
22 of the containing means 20; 24 is the means for regulating
pressure and in this example is a nut; 25 are the means for
positioning the block 18 and are solidly fixed to the front
outer plate 21, being equipped with holes 26 for hooks; said
means 25 could belong to the front plate 21 and be independent
in the case of each block 18 or cooperate with the other means
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25; 27 is a closure plate on the same plane as the structure
11 of the cover 10 and is positioned at the ends 110 thereof.
In operation, the blocks providing the seal 18 are
inserted into the ends of the channels 15 of the covers 10 of
suction boxes already equipped with dewatering foils 14, as
in Fig. 1.
The blocks 18 are positioned on the plate 27 of the
structure 11 of the cover 10 at the desired point and are
clamped there by screwing the nut 24 on to the threaded bolt
23. More specifically, the block 18 can be moved backwards
and forwards along channel 15 by means of prong 25. h'hen
positioning has been carried out, the block is clamped by
tightening nut 24, for in this way the rear outer plate 22 is
brought nearer to the front outer plate 21, thereby compressing
the part that can be deformed 19 lengthwise. Being compressed
lengthwise, part 19 swells on its lengthwise sides 28, which
by swelling move to their position 128 and press against the
sides of the dewatering foils 14. In this way, blocks 18 are
clamped along channels 15, thus ensuring a lateral end seal
of channels 15.
The lower and upper seal, on the other hand, is
obtained by the swelling caused by compression of the upper
and lower sides of the block 18.
There has been described herein a preferential
realization of the invention but variants thereof are possible;
thus it is possible to alter the shapes, proportions and sizes.
It is possible to envisage a block 18 embodying
several parts which can be deformed 19 and which are positioned
between the compression plates 21 and 22.
The containing means 20 could consist of a structure
with an open ring at least on the sides facing the dewatering
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foils 14. In such a case, the upper and/or lower end seal is
obtained by the containing means themselves 20, whereas the
lateral end seal is ensured by the deformable element 19
contained in said means 20.
It is also possible to envisage means suitable for
activating the clamping means 23 simultaneously and also to
envisage means suitable for positioning all the blocks 18
simultaneously.
These and other variants are possible for an expert
in this field without departing thereby from the scope of the
following claims.
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