Note: Descriptions are shown in the official language in which they were submitted.
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~ACKGROUND OF THE INVENTION
The subject invention concerns a msthod of manu~
factoring filtsr units comprising a plurality of filter
tubes of synthetic fibres and natural ~ibr~s, and a
machine designed to perform the method.
Prior-art multi-tube filters su~fer from several
drawbacks as regard the manufacture and the assembly as
well as the Function of the filters.
Hitherto, lengthwise stitched seams havs been used
to producs th~ filterJ whioh is a very time-consuming `~
method~ It takes several hours to sew in the conventional
manner a filt~r unit having a cross-section of 1 by 1 meter
and a tube length o~ 1 meter~ In the manufaoture, only
one tube row may be producsd at a time9 lengthwise seams
in two interconnected parts of the material delimiting
separate filter tubes The rows of filter tubes are then
stitched together at one end to form a filter unlt.
A ~ilter produced in this way lacks.inharent
stability and in order to uperate as an efficient filtsr
it must be stayed by means of special supporting~ profiled
rods which are inserted into sach individual tube to keep
it distended. Naturally, the applicatlon oF spacial
supporting profilsd rods into each tube is a time-consu~ing
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task. In addition7 it incrsases the total weight of the
filter unit~ On account of the ra~ulting considarable
weight of the filter unit, the latter becomss difficult
to handle during assembly, and in addition the filter
material which is to support both its own weight and th~
supporting profiles, i5 expose~ to considarable str3ssO
~ecause in oparation the filter tubes moua somewhat~
relative to the supporting pro~iled reds on account of the
streams of gas passing through them, the rrds cause a
certain amount of wear on the filter material. A further
disadvantage inherent in these prior-art multi-tubs filters
i5 that the support profiles~ one insida each tube, occupy
a considerable portion of the filtering area of the fîlter
unit, thus considPrably reducing the capacity of
the filterc
Finally should be pointed out that the collapsing
pressure, i.e. the maximum pressure that the filter is
capable of withstanding7 is comparatively low on account of
the stresses exerted c3rl the filter unit on account of its
heavy weight. The same is true as concerns the cleaning
pres~ure, i.e. the maximum allowabls flow of air in the
reverse flow direction through the filter to cl~an the
latterO
The abo~e-merltioned disadvantages are comple~ely
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eliminated in the filter produced in accordance with the method of
the subject invention.
SUM~ARY OF THE INVENTION
The method in accordance with the invention is
characterised in that the filter is manufactured from a continuous
material web advanced from a supply roll by
advancing a first part of the web the length of which is
equal to the desired length of the tubes,
folding a second part of the web at one end of said first
part and feeding said second part above said first part to the
opposite end thereof while simultaneously welding together, glueing
together or stitching together said two parts by parallel, lengthwise
seams/joints, thus forming a first row of neighbouring filter tubes,
folding a third part of the web at the last-mentioned end
and advancing said third part above said second part and
interconnecting said second and said third parts by lengthwise
welded, glued or stitched seams extending essentially halfway between
said first-mentioned welded, glued or stitched seams, thus forming a
second row of filter tubes,
advancing the subsequent part of the material web above
said third part and joining said part to said third part by
lengthwise seams/joints positioned straight above said
irst~mentioned sea~s/joints to form a third row
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of filter tubes9
and repeating ths procedure until the desired
number of connected rows of filter tubes i.s formed.
Because adjacent rows of f.ilter tube~s are inter-
connected by ~eans of seams or joints which extend in
the lrdngthwise direction of the tubes at the tubs centrssy
the tubes are automatically distended when the~filter unit
is mounted in frames positioned at the ~ilter unit ends,
The application of spscial supporting pxofiles inside the
tubes thus becomes s~erfluous, which result~ in considerable
time~saving when the filter units are mounted and also means
that the entire tub0 area may serve as a filtering area
without impadirnant of profilsd rods. In addition~ the total
weigh-t of the filter unit is greatly reduced as a result
of the elimination of the supporting prof'iles. The ~ilter
unit in accordance with the invention has a total weight
of between 15 and 20 ki~os for a cross-section size of
1 by 1 meter and a tube length of 1 meter, whereas prior-art
filters of this type for the same size and including
supporting profiled rods has a weigth of about 40 kilos.
~RIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in closer detail
in the fnilowing with refsrence to one embodiment thereof
illustrated in the accompanying d~awings, wherein
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Fig. 1 is a partly broken view fro~ above of a machine
in accordanGe with the invention designed to produce a
multi-tub~ filter~
Fig 2 shows the machine in aGcordance with Fig~ 1
in a partly broken lateral ~iew,
Fig ~ 3 illustrates the machine of Fig. 2 during
a later stage of the manofacture of ths filter,
Fig 4 .illustrates on an enlarged scale a se~tion
through certain details of the machine in order ~o
illustrate the manner o~ cooparation between a movabla
table incorporated in the device and a pressing element
designed to advance a ~aterial web, and also the mannar
of cooperation between the pressing element and wel~ing
memb~rs de~igned to weld together the material web,
Fig 5 illustrates the details of Fig 4 in a view
from above,
Fig 6 shows one c~rner o~ two parts welded together
~to Form a row of tubular filters,
Fig 7 shows a filtsr unit manufactured in the
mach.ine, the unit being distended to form a multi~tube
~ilter t
~ i~. 8 shows a ~ulti-tube filter in accordan~e
wlth Fig. 7 in a partly breken view as s~en from one end~ and
Fig 9 illustrates tha arrangament of saveral
multi~tube filters in a large ~iltering apparatus.
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The ~achine in accordance with Fig 1 incorporate
a table 3 which is arranged to move between a first and a
second limit ~eans 1 and 2. Tha table 3 is pro~id0d
wLth two pa1rs of wheels, the wheels o~ one paLr bein~
prouided with thseth for engagemr3nt wi~h racks ~ whsreas
the wheels of the secorld pair 5 run fr~3ely ~n rails 79 ~.
The shaft of whs3el pair 4 is driven by an electric motor
9 which is positioned on the lower face oF the displacr~able
table 3~ The machine also comprises a frarna including
lengthwise beams 10, 11 positioni3d straight above the
rails 7, ~ and interconnected with the transverse b~ams 12
13 of the frame. On the beams 10, 11 is mounted a supply
roll 14 holding filter material. On the external face of
the beams lD9 11 are arranged two cooperating pistons 15
and 16 which are arranged to be raised and lowered for
displacement of brackets 17, 1~ mounted thereon The latter
are interconnected by a beam 19 arranged at ona of the
brackat ends and by a shaft 20 positioned at the oppos~te
bracket ends. The beam 19 supports pistons 21, 22? serving
to displace a rail 23 along which àre provided e9uidistantlY
spaced welding mernbers 24. The welding mernbers 24 may he in
the forrn bf hot air nozzles or in the ~orm of electrically
haated welding jaws or collector shoes The shaft 20
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mounted in the brackets supports a presser means
gsnerally designatsd 25 along which are provided
equidistantly spaced press rings 26, Also on the internal
faces af .the beams 10, 11 are provided two coopsrating
pistons 27, 2a which may bs raised and lowered to displace
brackets 299 30 mounted thereon. These brackets are
interconnscted by a beam 31 positioned~at one o~ the bracket
ends and by a shaft at the opposite one o~ the bracket
ends. Pistons 329 33 are mounted on the beam 31 and are
arranged to dieplace a rail 34 which is pruvided alonQ its
length with equidistantly spaced welding members 35.
The shaft mountsd in the brackets supports a prssser means
g~rally designated 36 and a~long which are provided aqui-
distantly spaced press rings 37.
As appears ~rom Flg, 27 the move~lents of respectiuely
brackets 179 18 and brackets 29~ 30 are controlled by
associated vertical controlling rads 38, 39, and 40, 41,
During manufacture o~ th~ filter a continuous matsrial web
42 runs from the supply roll 14 so as to extend bet~een
each pair of ~rackets 17, 18 and 29, 3D, respectively, and
between each one o~ the presser means 26 and 38 and the rails
23 and 34 associated therewith,
Figs3 4 and S show the structure of the welding
members and the press rings in closer detailO The welding
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rnembers 24 have a fork-shaped attachment section 43 which
is arranged to engage the beam 19, The latter .is
provided on its upper f ace wi th a lengthwi~e groove 44.
The welding members are cla~npad to the bea~n by mrtans of
bolt~ 45 which are screwed into locking melab~rs 46 in
the beam interior. This makes it p~ssibl~ to set th~ :
welding members in any arbitrary p~sition along the beam~
F~lding rulers 47 are posi-tiuncd betwaen the
welding members 24~ Like the welding membrrs the ~olding
rulers are provided with a fork-shaped attachment section
48 with the aid of which the rulers may be secured to the
beam by means of bolts 49 and locking members 46 provided
in the beam interior. As appe~s from Fig. 4, the pistons
21, 22 and 329 33, are cor.nected to their respective beam
by means of attachments 19~. Each one of ths press rings 26
provided on presser means 25 is equipped with a flange 50
in which a threaded hole is formed to receive a lockin~
screw 51 therein, Conssquently, the press r~nss 2~ may be set
in any arbitrary position along the prasser means.
In the manufacture of a rnulti-tube filter a first part
52 o~ material web (see FigO 2) is pulled ~anually aornss
the tab.~le 3, while ensuring that the part has a length which
i9 equal to the desired length of the filter tube~ The
table 3 is provided with crosswisa bur ~astener strips
537 54 ssrving to secure and retain the first part 52 o~ :
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the web positioned on top of the table. ~le pistons 32, 33 displace
the rail 34 with the welding members 35 thereon obliquely downwards
in the direction towards the tangential line between the table 3 and
the press rings 37, whereby the folding rulers 47 bring along the
material web 42 in their movement such that a fold is formed in the
web between the table and the press rings. In Fig. 2, the machine is
shown in a position immediately following this foldingO The table is
then moved in the direction of arrow A in Fig, 2, while at the same
time the presser roller is driven at such a speed that the peripheral
speed of the press rings coincide with the speed of the table. The
material web will then be withdrawn from the supply roll at the same
speed as the table, whereby a second part 55 of the material web is
pressed against the first one at the rate of advancement. The part
52 of the web 42 withdrawn from the supply roll 14 and fed in
underneath the press rings 37 is heated by the welding members 35,
whereby the synthetic fibres and natural fibres in the material web .,
are softened alo~lg lengthwise runs and when the two web parts 52, 55
are pressed together below the press rings 37 which are positioned
opposite the welding members 35, the two parts will be interconnected
by lengthwise welding seams.
~aving been displaced in the direct of arrow A
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up to the second limit means 2, the table 3 remains in
this position until the welding members 35 on rail 34
and the folding rulers 47 are moved out nf their engagement
with the material web 42 by pis-tons 32, 33, which r~turn
to their fully retracted position, In thlis positi~n the
welding members and the folding rulers are positioned
laterally offse-t relative to the vertical path o~ movemsnt
o~ the presser means 25 secur0d in brackets 17, 18. The
braokets 29, 30 and consequently also pressing roller 36
and rail 34 may be li~ted by pistons 27~ 28 from the table,
The brackets 17 and 1~ and therefore also pressing means
25 and rail 19 may at the same time be lowered by pistons
15, 16. When the brackets 17; 18 are in their lower position~
the rail 23 together with the welding members 24 thereon
and the folding rulers are displaced in a direction
obliquely downwards against the contacting line between
the press rings 26 and the doubled material web on the
table9 whereupon the folding rulers bring along the material
web 42, folding the latter, Fig, 3 illustrates the machine
immediately after this foldingJ
The table is then displaced in the direction of
arrow ~ in Fig. 3 while at the same timB presser means 25
is driven at such a speed that the peripheral speed of
the press rings will agree with the speed of the table. As
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a result, the material web will be unreeled from the
supply roll at tha same ~peed as the table and a third
part of the material web will be prsssed against the
second one at the rate Qf advancement~ The part 55 of the
web 42 unrseled from the supply roll is passed in under~
neath the press rings 26 and heated by the welding membars
24 along lengthwise runs and when pres$ed tog~ther b~low
the press rings ~6 the two heated parts are welded together
along lengthwise welding seams.
As appears from Fig. 1, the press rings 26 and their
associated welding members 24 in alignment therewith are
positioned half way between,i.e. staggersd relative to,
the press rings 37 and their associated welding members ~5.
The filter tubes formed by the welding together of the first
two web parts 52, 55 thus are interconnected to the third
material layer by means of lengthwise welding seams at the
centre of ths t~bes during the application of the latter
layer.
The third web part is then welded to the ~ourth
part in the same manner as the first part was welded to
the second one, i.e. with the welding seams between the
parts in alignment with the welding seams b~tween the first
and the second parts 52, 55.
The multi-tube filter is produced sucGe~siuely in ~;
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the manner desoribed above until the desired number of
connected rows of filtar tubes i5 achieved.
When the web parts are welde~ together9 jt is not
possible to extend the welding seam all the way up to the
folding line but, as appears from Fig, 6~ ths welding seams
56 stop a short distancs away from the folding line. Each
row of filter tubes tharefore must bs provided at their
corners with a welding seam 57 in order that the filter
be sealed
When the multi-tube fil-ter praduced in the ~anner
indicated is disten~ed in a direction at right angles to
the lengthwise extension as well as to each row of Filter
tubss, all filter tubes of the filter package unit are
extended in a bellow-like manner (Fig~ 8) as a result of all
tubes oF one row being intercorlnected at their centres to
the adjacent tubes of the neighbouring rows at the centres
of those tubes by means of lengthwise weldlng SQamS,
Fig. 7 shows a filter nO mounted in frames 5B, 59 in
distended pcsi~tian. In the manufactur~ of the filter package
in the machine the web parts of the first and last rows
are made somewhat longer than the rest. The mounting of
tho filter in the frames sa, 59 is effecte~ with the aid of
these prolonged parts two of which, designated 619 62 are
shown in the drawings, and also with the aid of an additional
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tl~o parts at eaoh end of the filter, which part~ are '!~
preferably sewn onto the filter. The latter parts
stitched to the ~ilter are designatsd 639 64 in Fig. 8,
The filter is mounted in distended position in the ~ra~ss
in that said prolongsd parts and the stitchad-on parts ,~
are ~lded about the frame which is of U-shapsd cross~
sectionsl configuration~ and ars secured by sealing
strips 65, 66 (see Fig, 7) which are pressed into the
recess o~ the frame SD as to olam~gly secure the parts
to the fr~me.
The filter unit mounted in the frames may, as
appears from fig. 7p be suspended in attachment beams 67 in
a filter duct,
Equdistantly spaced over all faces oF the filter
60 are attachment pockets 6~, Fig, 7 shows three rows of
attachment pockets of this kindO Into the attachment pockets
are inserted from each side of the ~ilter support rods or
support pipes 69 which are connectsd to adjacent support
pipes at the ~ilter corners. The support pipes assist in
keeping the filter in a fully distended condition9 ensuring
that the fillter tubes remain opon over their ent,ire length
and are nok de~lated by the gas pressure exerted on thsm
~rom the outside~
The cross-sectional parts shown in Fig. 7 illustrate
the appearanoe oF ths ~ilter interior in th~ distended and
mounted position thereof. Tha section is taken rectilinearly
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through the welding seams that lnterconnect the filter
tubes of neighbouring rows, In the drawing figur~9
these welding seams are designatod by numeral 70. The
welding seams which dalimit the individual filter tubss
of each row are designa-ted by 71~ Each indiuidual filter
tube thus i5 delimited by two opposite welding seams 70
and two opposite welding seams 71~ When a ~iltsr unit
which after manufacturs thereof in the machine f~rms a
flat package is to be distended, one sxtends tha filter in
a direction at right angles to the rows of ~ilter tubes.
As a result, the two opposite welding seams 70 of each
~ilter tube are mo~ed away from one another while the other
two opposite welding sea~ 71 approach one another. The
fîlter tubes thus will have arl essentially rectangular
cross-sectional shape,
Fig. 8 illus-trates in a partly broken view a filter
in th0 distended position thereof as seen from one end of
the filter~ The filter as shown is mounted~in a support
pipe 69 but not yet attached in the framss~ The appearance
of the multi-tube filter as seen from one end thsreof with
the various raws of filter tuoes appears from this figurc.
The figura also shows in the cross-sectiorlal view of the
corner the appearanoe of the filter tubes in distended
position.
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Fig. 9 shows a cleaning apparatus 72 incorporating
a plurality of "cass~ttes" or cartridges of multi-tube
filter units 73, 74, 75 producad in accordance with the
t.eachings of the invsnti~n~ The filter units are suspended
from the Geiling ?7 of the filtaring oharnber 76 in tha
manner shown in Fig. 7~ Fumes to be cleaned ~low through
the inlet conduit 7~ into the filtering chamber 76 and uia
the multi-tube f`ilters to a space 7g ~rorn which the cl~aned
gas i~ discharged into the surrourlding atmosphere via the
outlat conduit 80.
When the multi-tube filters are to bs cleaned9 tha
inlet opening 7~ is closed by a baffle 81 and air is blown
into the apparatus in reverse flow direction9 iOe. through
the inlet opening ao, through the filters and down into
chamber 76, whereby the dirt and impurities collacted in
the filter tubes come loosaA Air blown in through the inlet
opening to clean the filters is evacuated through an opening
(not shown) close to the bottom of chambar 76, where tha
impurities are collected, e.g, in an air-permsable bag
(not shown,). Heavier particles fall dQwn to th~ bottorn
of the chambar 76 when~,Q~ they are withdrawn frorn the
apparatus by a scx~w wo~m pump 82.
The method and the machine f`or~hs rnanufacture of
mulki-tube filters in accor~ance ~ith the invention are not
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limited to the exampls given abovs but several madifications
are possible within the scope of the appended claimsO
The presser means and the welding members associated
therewith obviously nee~ not be mounted on the very same
bracket but it is equally possible to mount the presser
means and the welding members associatEd therewith separately
and arrange for operation thereof by separate pistons.
In accordance with the embodiment shown the prEsser
means and the welding members are pressed against the
material parts on the table by their own weight. However~
the maohine may be supplemented by resilisnt means serving
to urge the pressing means against the material ~eb and
forcing the welding members to aout on the weh.
In the machine described above the multi-tube filter
is interconn~cted by welding. nbviously, it i9 possible
to modify the machine in a manner permitting the filter to
be glued together. It is likewise possible to stitch the
~ilters together~ In the latter case more extensive modi-
fication of the machine is required. For instance, upon
stitching of one row support rails must be provided in
the soparate pockets at least in the row of ~ilter tubes
positioned immediately below.
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