CA1095223A - Method and a machine for manufacturing multi-tube filters - Google Patents

Abstract

Abstract of the Disclosure A method and a machine for manufacturing multi-tube filters. The filter is manufactured from a continuous material web which is folded in zigzag, one layer upon the other, the length of the respective layer corresponding to the desired length of the filter tubes. During the folding of each layer, said layer is joined to the layer below by parallel, lengthwise seams, whereby rows of contiguous filter tubes are formed and neighboring rows of filter tubes are joined together.
The seams that delimit the respective tubes in a row of filter tubes are positioned in alignment with the corresponding seams in all the other rows of filter tubes and the seams that join together neighbouring rows are positioned right between said tube-forming seams. The interconnected layers form, when the filter unit is extended in a direction at right angles to the layers, a filter unit comprising a plurality of tubes that are essentially square in cross-section.

Description

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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 , ~95~3 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 ~ . - , : ~ .. :

2~3 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 - ''".

5;~ 3 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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5~;23 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.
:~ ' 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 "

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 ~, _ 7 - ~

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~5~23 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

5;2~3 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 -- 10 -- , ~5~3 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 5:~23 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 - 13 _ . . . ~.

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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 - 15 _ . .
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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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Claims (21)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An improved method for manufacturing multi-tube filters of synthetic fibres and natural fibres, the improvement comprising manufacturing said filters from a continuous material web unreeled from a supply roll by advancing a first part of said web, the length of said web part being equal to the desired length of the filter tubes, folding a second part of said web at one end of said first part and feeding said second part above said first part to the opposite end thereof while simultaneously joining together said two parts by parallel lengthwise seams, 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 seams extending essentially half-way between said first-mentioned seams, thus forming a second row of filter tubes, advancing the next part of said material web above said third part and joining said next part to said third part by lengthwise seams positioned straight over said first-mentioned seams to form a third row of filter tubes, and repeating the procedure until the desired number of interconnected rows of filter tubes is formed.

2. An improved method as claimed in claim 1, comprising said seams being formed by welding.

3. An improved method as claimed in claim 1, comprising said seams being formed by glueing.

4. An improved method as claimed in claim 1, comprising said seams being formed by sewing.

5. An improved method as claimed in claim 2, comprising melting said synthetic fibres and said natural fibres of said web parts in mutually parallel rows in the longitudinal direction of said parts during the advancement of said web parts, and pressing said web parts together, whereby the fibres of one web part are interconnected with the corresponding fibres of the adjacent web part so as to form said filter tubes.

6. An improved method as claimed in claim 3, comprising glueing said synthetic fibres and said natural fibres of said web parts in mutually parallel rows in the longitudinal direction of said parts during the advancement of said web parts and pressing said web parts together, whereby the fibres of one web part are interconnected with the corresponding fibres of the adjacent web part so as to form said filter tubes.

7. An improved method as claimed in claim 1, comprising mounting the unit formed by said interconnected rows of filter tubes in rectangular frames at opposite ends of said unit, distending the tubes delimited by said seams.

8. An improved method as claimed in claim 7, comprising arranging attachment pockets on the external faces of said unit mounted in said rectangular frames in distended condition in a number of rows in parallel with said frames, applying support stays through said pockets in each row, and interconnecting the stays on one side face of said unit with adjacent stays at the unit corners.

9 A machine designed to produce multi-tube filter units composed of interconnected rows of filter tubes, comprising a table arranged for displacement between two limit means, a supply roll holding a continuous web of filter material, first and second presser means arranged alternatingly in response to the direction of displacement of said table to press said material web in the direction towards said table, a number of interconnecting members associated with their respective one of said first and said second presser means, said interconnecting members arranged in their operative position to interconnect a first part of said web positioned on top of said table and a second part of said web, said second part folded over said first web part when withdrawn from said supply roll in underneath one of said presser means at the pace of displacement of said table, said interconnection performed along lengthwise runs, whereby said first and said second parts are loined together by lengthwise seams, when said last-mentioned presser means presses said parts together, means to control said displacement of said: tables, and means arranged to disengage one of said presser means and the interconnecting members associated therewith from their engagement with said web and bring the other one of said presser means and the interconnecting members associated therewith into engagement with said web in response to said table abutting against the respective one of said two limit means.

10. A machine as claimed in claim 9, wherein said presser means are press rings arranged on a shaft.

11. A machine as claimed in claim 10, wherein said press rings and their associated interconnecting members may be set in arbitrary positions along the width of said web.

12. A machine as claimed in claim 10, wherein said press rings are peripheral beads formed on a roller.

13. A machine as claimed in claim 9, wherein said interconnecting members are welding members in the form of hot air nozzles.

14. A machine as claimed in claim 9, wherein said interconnecting members are welding members in the form of electrically heated welding jaws or shoes.

15. A machine as claimed in claim 9, wherein said interconnecting members are glueing members such as glue spreading nozzles.

16. A machine as claimed in claim 9, wherein said interconnecting members are stitching members in the form of sewing machine heads.

17. A machine as claimed in claim 10, comprising spring means arranged to press said press rings of said first and said second presser means against said web.

18. A machine as claimed in claim 9, comprising spring means arranged to bring said interconnecting members into abutment against said web.

19. A machine as claimed in claim 99 comprising a piston, said interconnecting members connected with said piston to be displaced together with said piston in the direction towards and away from their said associated press rings.

20. A machine as claimed in claim 9, comprising a number of pistons, said interconnecting members connected separately or in groups with said pistons to be displaced together with said pistons towards and away from their said associated press rings.

21. A machine as claimed in claim 10; comprising a number of folding rulers between said interconnecting members in alternate positions therewith, said folding rulers arranged to fold and guide said web of material unreeled from said roller in between said table and said press rings abutting against said table.