GB2172693A

GB2172693A - Gas filter

Info

Publication number: GB2172693A
Application number: GB08601150A
Authority: GB
Inventors: Gerhard Lupnitz
Original assignee: A Monforts GmbH and Co
Current assignee: A Monforts GmbH and Co
Priority date: 1985-03-20
Filing date: 1986-01-17
Publication date: 1986-09-24
Also published as: JPH0633566B2; IT1186247B; DE3510005C1; FR2579306B1; GB8601150D0; FR2579306A1; JPS61215763A; IT8523387A0; GB2172693B

Abstract

In order that the circulating air current of a convection drying and/or fixing machine, provided for the treatment of a textile cloth web, may be cleaned without interruption of production, in the air circulation passage cross-section a sieve belt length 17 is stretched which is to be rolled up on one side, through a slot in the machine wall, reversibly on a shaft 14 mounted outside the interior space of the machine, and tensioned by a cable 20. <IMAGE>

Description

SPECIFICATION Cleaning device of a convection drying and/or fixing machine The invention relates to a cleaning device of a convection drying and/or fixing machine designed for air circulation treatment of a textile cloth web or the like, having a sieve belt mounted for displacement transversely of an air circulation passage approximately horizontally to and fro in the interior space of the machine and for rolling up on a shaft, for the filtering of slubs or the like deposits out of the circulating air current, in which a return force acting against the roll-up force allocated to the shaft is applied to the longitudinal end of the sieve belt remote from the shaft.

A cleaning arrangement of this kind is set forth in Fed. German Publ. Spec. No.

3,234,436. The known sieve belt can be rolled to and fro within the interior space of the machine between two shafts on to which it can be wound alternately. With the sieve belt there are associated suction devices with the aid of which slubs or the like deposited out of the circulating air current to be cleaned can be removed by the sieve belt as it rolls to and fro. In many machine constructions however the space requirement of the two sieve constructions and the suction devices within the machine space cause considerable problems. In Fed. German Publ. Spec. No.

3,234,436 an alternative device with an endless sieve belt conducted over rollers transversely of the air circulation passage and through slots to the machine exterior and back again is also described. While in this case the space requirement immediately adjoining the region of the air circulation passage to be provided with the slub filter is reduced, instead however sieve belt guide rollers inside and outside the machine and tight slot passages through the machine wall are required. Furthermore an essential disadvantage consists in that the circulating air current must flow through the sieve belt twice, namely once in filtering and once after filtering. Thus in the cleaning of the sieve belt any deposits which have still remained there are lifted away from the belt in the second flow through it and thus pass afresh into the circulating air current.Finally the production of an endless sieve belt is relatively expensive.

It has also already been proposed (see Fed.

German Patent Application P 33 36 332.3 of the 6th October 1983) to provide an endless sieve belt conducted over rollers which is guided for one. part over a roller situated within the machine interior space and through a single slot of the machine wall to a reversing roller provided outside the machine wall. In this case in fac#t the removal of deposits from the sieve belt can take place exclusively outside the machine, so that corresponding equipment is not necessary in the interior space of the machine. However the roller which reverses the sieve belt in the interior of the machine still constitutes a hindrance for the various units provided in the machine.In the sieve belt device as proposed it is also impossible to preclude the cleaned part of the sieve belt, in the re-entry as lower run into the interior of the machine, still carrying a residue of slubs or the like deposits which are then blown from the lower run by the gas flowing in the machine, and arrive in the machine parts to be protected.

In Fed. German Utility Model No. 1,834,526 there is further indicated a sieve belt for a heat-treatment machine which stretches over a radiator of a circulating air current to be cleaned. While the space requirement of this cleaning device in the machine interior is minimal and the removal of filtered-out deposits can take place on the exterior of the machine, the reversing rollers of the sieve belt are however mounted on the exterior of the machine a the two ends of the run stretching over the radiator, so that appropriate passages, coverings and seals are necessary.

The invention is based on the problem of providing a cleaning device comprising a sieve belt for winding on a shaft for a convection drying and/or fixing machine, for example for a tentering frame or a "hot flue", in which the return force necessary for holding fast and retracting the other longitudinal end, opposite to the shaft, of the sieve belt does not require voluminous fittings within the machine or special ducts to the exterior and in which the circulating air to be cleaned flows only once through the sieve belt, that is always in the same direction.The solution according to the invention consists, for the cleaning device with a sieve belt mounted for displacement to and fro in the machine interior space transversely of an air circulation passage and for rolling up on a shaft, in that the shaft is mounted outside the machine interior space and the longitudinal end of the sieve belt secured to the shaft is conducted through a slot of the machine wall and in that a draw cable, conducted back through the slot or a hole beneath the slot to the shaft and there wound up oppositely to the sieve belt, acts as return force upon the other longitudinal end of the sieve belt.

Thus in this solution the return force is supplied by the rolling-up force acting simultaneously upon the sieve belt and upon the draw cable. Alternatively the solution in accordance with the invention also consists in that a draw spring acts as return force upon the other longitudinal end of the sieve belt, or in that a counter-weight is suspended over a pulley as return force on the other longitudinal end of the sieve belt.

In the arrangement according to the invention the sieve belt is formed for rolling up solely on the shaft, which remains outside the machine, against a return force directed into the interior of the machine. For cleaning the sieve belt is rolled up on the shaft and -cleaned there at the same time in rolling up.

In general only the part of the sieve belt nor mally exposed to the circulating air current of the machine is accessible to this cleaning.

During the cleaning therefore a protective sieve adjoining the sieve belt and of approxi mately the same mesh width as the sieve belt should be drawn into the filter position transversely of the air circulation passage.

Since the cleaning and the moving of the sieve belt to and fro proceed relatively quickly, no appreciable soiling of the protective sieve takes place. This therefore needs to be freed of any deposits only in a thorough cleaning of the machine.

The protective sieve can be attached as a separate component to the longitudinal end of the sieve belt opposite to the shaft or can itself form an extension of the sieve belt. In the latter case the part of the sieve belt which is cleaned at regular intervals by drawing out of the machine can be called the main sieve and the part of the sieve belt which covers the air circulation passage only during the cleaning phases can be called the auxiliary sieve. Especially if the air circulation passage conducting the circulating air current to be fil tered adjoins the machine wall containing the slot, in this connection it can be favourable to provide the main sieve and the auxiliary sieve with approximately equal working lengths covering the air circulation passage.

According to a further part of the invention a suction nozzle extending over the width of the sieve belt for the removal of accumulated deposits is directed on to the sieve belt in the slot of the machine wall provided for the pas sage of the sieve belt. Due to this application of suction to the sieve belt immediately at the edge of the machine cross-section or air circu lation passage to be protected, the stroke. of the sieve belt necessary for a complete clean ing of the main sieve is reduced to the abso lute minimum. With negative pressure prevail ing in the machine interior, the application of suction to the sieve belt directly in the slot of the machine wall also obtains an essential further advantage. Without-the suction provided for cleaning, in fact air would be sucked in wards from the exterior.This sucked-in air is undesired not only because of its# cooling effect but above all because it can blow slubs or the like situated on the sieve belt into the interior of the machine, in such a way that in the drawing out of the sieve belt only a part of the slubs situated on the belt is conveyed out of the machine. If however a suction is already provided in the slot of the machine wall, a reversal of the air flow direction results in such a way that not only is the inwardly directed air suction in the slot eliminated but also slubs arriving in the region of the slot can be conveyed or sucked away to the exterior without problem.

The draw cable which holds the sieve belt in each case taut and retracts it into the working position can act, in the various alternatives according to the invention, either in each case upon one sieve belt or, through a yoke, upon two or more sieve belts arranged side by side at the same time. Especially in the alternative in which the draw cable is conducted back to the shaft and there wound in the opposite direction to the sieve belt, it can be favourable to equip the yoke and/or the draw cable itself with spring systems compensating for a thermal stress, different winding diameters, etc. If the yoke acts for example on two sieve belts arranged side by side at the same time, the draw cable, to be wound up on the shaft oppositely to the sieve belts, is rolled up in the middle between the sieve belts on to the shaft, especially on to a draw cable winch arranged there.

Details of the invention will be explained by reference to the diagrammatic representation of examples of embodiment, wherein: Figure 1 shows a cross-section of a sieve belt cleaning device having a draw cable for winding up oppositely to the sieve belt on a shaft outside the machine space; Figure 2 shows a plan view of two sieve belts according to Fig. 1 lying side by side; Figure 3 shows a cross-section of a cleaning device with sieve belt held taut by a spring or a counter-weight; and Figure 4 shows a plan view of sieve belts according to Fig. 3, lying side by side.

In Fig. 1 there is diagrammatically represented a vertical section transverse to the longitudinal direction of a tentering frame. The cloth web 1 to be treated is held at the longitudinal edges in chains 2 and 3, conducted in a direction perpendicular to the plane of the drawing through between the nozzle chests 4 and 5 and in this movement treated from above and below with the gas supplied from a fan 7 in the direction of the arrows 6, especially with heated air. The gas flowing back from the cloth web 1 in the direction of the arrows 8 is sucked in again, at least for the most part, by the fan 7 and blown afresh in the cycle on to the cloth web 1. If the circulating air current is to be heated, in the example of embodiment it is conducted on its way from the cloth web 1 to the fan 7 through a heat exchanger 9 or through a combustion chamber 10, for example with direct gas heating 11.

Since slubs, threads and similar deposits can be detached from the cloth web 1 in its impingement with the treatment gas, in general a filter sieve is inserted into the return air current flowing in the direction of the arrows 8. In order to render it possible to clean this filter sieve while work is continuing, that is without opening a door in the cladding or wall of the machine, a filter sieve is provided in an air circulation passage cross-section 13 constricted by a suction chamber plate 12.

In accordance with the invention as filter sieve there is provided a sieve belt 17 for winding up on a shaft 14 in the direction of the arrow 15 outside the interior space 16 of the machine. In accordance with the invention the longitudinal end 19 of the sieve belt 17 lying opposite to the longitudinal end 18 adjacent to the shaft 14 is adjoined by a draw cable 20 which is reversed in the machine space 16 over a roller 21 and conducted back to the shaft 14 through a slot 22 in the machine wall 23 which is necessary in any case for the guiding through of the sieve belt 17. It is essential here that the draw cable 20 be wound oppositely, that is in the direction of the arrow 24, on to the shaft 14 or a cable winch 25 (see Fig. 2) arranged thereon. The sieve belt 17 can extend continuously between the two longitudinal ends 18 and 19.

However a step 26 can be provided between the two sieve belt parts, which are then to be designated as main sieve 17a and auxiliary sieve 17b. In the movement of the sieve belt to and fro in the direction of the arrows 27 for the purpose of cleaning only the main sieve 17a is wound on to the shaft 14. During this action the auxiliary sieve 17b is used as filter in the air circulation passage cross-section 1.

According to Fig. 2, with the aid of one single draw cable 20 it is possible for two sieve belts 17, lying side by side, for rolling up on a shaft 14 outside the wall 23 of the machine, to be stressed in the longitudinal direction or drawn to and fro in the direction of the arrows 27. For this purpose the preferably reinforced longitudinal ends 19 of the sieve belts 17 are coupled with a common yoke 28 which can be drawn with the aid of the draw cable 20 in the direction towards the roller 21, preferably against a compensating spring system 29.In the arrangement according to Fig. 2 with draw cable 20 conducted through between two sieve belts 17 lying side by side, one advantage consists in that the draw cable can be wound up on a separate cable winch 25 secured on the axle of the shaft 14, and therefore oppositely directed winding side by side on the shaft 14 or on the cable winch 25 is rendered possible.

Thus one single drive is needed for the winding up of the sieve belt 17 and for the contrary winding of the draw cable 20. In the example of embodiment according to Fig. 1 for this purpose a geared motor 31 connected through a drive belt 30 to the shaft 14 is indicated. A programmed control system can be allocated to the motor 31 in such a way that the main sieve 17a is automatically wound on to the shaft 14 for the purpose of cleaning and then immediately wound back into the working position, at certain pre-determined time intevals. To compensate for any fluctuations of length of the draw cable 20 caused by thermal or mechanical differences, an additional compensating spring system 32 can be inserted into the cable 20.

A negative pressure can prevail in the region of the interior space 16 of the machine adjoining the air circulation passage cross-section 13, due to the suction power of the fan 7. Thus in the absence of special precautions external air can be sucked through the slot 22in this region into the interior of the machine. In the example of embodiment according to Fig. 1 this suction can be avoided in that the suction nozzle 33 of a suction device 34 provided for the cleaning of the sieve belt 17 is provided directly in the slot 22 of the machine wall 23 serving for the passage of the sieve belt 17 and of the draw cable 20.

Due to the suction power of a blower (not shown) connected to the suction device 34 the pressure conditions in the region of the slot 22 are varied so that air can no longer be sucked into the machine interior 16 at this point. This also means that any slubs or the like present on the main part 17a of the sieve belt 17 can be removed with the suction draught 35 from the sieve belt 17 within the suction nozzle 33 and cannot be sucked back-as in the case of a sieve belt cleaning device provided further outside the machine-by any negative pressure acting from the interior 16 of the machine.

A second (and a third) example of embodiment of the cleaning device will be described with reference to Figs. 3 and 4. The machine as a whole and the sieve belt 17 with roll-up shaft 14 according to Figs. 3 and 4 can conform substantially with the corresponding components according to Figs. 1 and 2.

Therefore the references 1 to 19 have the same significance in Figs. 3 and 4 as in Figs.

1 and 2.

The essential difference of the example of embodiment according to Figs. 3 and 4 from the example of embodiment according to Figs.

1 and 2 concerns the nature of the return force acting upon the longitudinal end 19 of the sieve belt 17 and against the rolling-up force of the shaft 14. According to Figs. 3 and 4 as return force there can be provided either a tension spring 36 or a weight 39 acting by way of a pulley 37 and a draw cable 38 upon the longitudinal end 19 of the sieve belt 17. The length of the draw cable 38 of the counter-weight 39 and the stretch length to which the tension spring 36 can be stretched elastically must be at least equal to the width of the air circulation passage crosssection 13, measured in the longitudinal direction of the sieve belt.

In the example of embodiment the belt 17 consists of a main sieve 17a and an auxiliary sieve 17b adjoining the latter by way of a step 26. In normal operation the auxiliary sieve 17b-as also in the example of embodment according to Figs. 1 and 2~lies on the suction chamber plate 12 and thus is inactive.

It is required only when the main sieve is wound up on to the shaft 14 in the direction of the arrow 15, and during this relatively short cleaning time it replaces the main sieve 17a in the region of the air circulation passage cross-section 13. In Figs. 3 and 4 of the drawing the tension spring 36 is represented in its contracted condition. The auxiliary sieve 17b is then situated thus above the suction chamber plate 12. When the main sieve 17a is wound on to the shaft 14 in the direction of the arrow 15, for example by activation of the motor 31 acting through a belt 30 upon the shaft 14, the tension spring 36 stretches into the vicinity of the slot 22 provided in the machine wall 23 and serving as duct for the sieve belt 17.In this movement the auxiliary sieve 17b, coupled with the forward end 40 of the tension spring 36, is entrained, so that it closes the air circulation passage cross-section 13. If the auxiliary sieve 17b possesses a solid frame, on release of the main sieve 17a and unwinding from the shaft 14 in the direction of the arrow 27 by contraction of the tension spring 36 it is pushed back again into the region above the suction chamber plate.

In a similar manner the sieve belt 17 can be moved to and fro in the direction of the arrows 27 by the action of a rotating movement of the shaft 14 or of the weight 29. If in place of the tension spring 36 acting between the step 26 of the sieve belt 17 and the fastening 41 on the machine frame, the counter-weight 39 is used as return force, the auxiliary sieve 17b does not need to be provided with a solid frame, if the draw cable 38 acts upon the rear end 42 of the auxiliary sieve 17b.

Claims

1. Cleaning device of a convection drying and/or fixing machine designed for air circulation treatment of a textile cloth web or the like, having a sieve belt mounted for displacement transversely of an air circulation passage approximately horizontally to and fro in the interior space of the machine and for rolling up on a shaft, for the filtering of slubs or the like deposits out of the circulating air current, in which a return force acting against the rollup force allocated to the shaft is applied to the longitudinal end of the sieve belt remote from the shaft, characterised in that the shaft is mounted outside the interior space of the machine and the longitudinal end of the sieve belt secured to the shaft is guided through a slot of the machine wall and in that a draw cable conducted through the slot to the shaft and there wound up oppositely to the sieve belt acts as return force-upon the other longitudinal end of the sieve belt.

2. Cleaning device according to Claim 1, modified to the effect that a tension spring acts as return force upon the other longitudinal end of the sieve belt.

3. Cleaning device according to Claim 1, modified to the effect that a counter-weight is suspended over a pulley on the other longitudinal end of the sieve belt, as return force.

4. Cleaning device according to one or more of Claims 1 to 3, characteristed in that when the air circulation passage adjoins the machine wall containing the slot the sieve belt consists of a main sieve for winding up on the shaft and an auxiliary sieve adjoining its end remote from the shaft and covering the air circulation passage during the winding on of the main sieve and in that the main sieve and the auxiliary sieve possess approximately the same working length covering the air circulation passage.

5. Cleaning device according to one or more of Claims 1 to 4, characterised in that the draw cable engages preferably with compensating spring system in the middle of a yoke acting simultaneously upon two sieve belts arranged side by side.

6. Cleaning device according to Claim 1 or 5, characterised in that the draw cable is to be wound up in the middle between the sieve belts on to the shaft-oppositely in relation to the sieve belts-especially on to a draw cable winch.

7. Cleaning device according to one or more of Claims 1 and 4 to 6, characterised in that the draw cable reversed in the part of the machine frame remote from the shaft contains a compensating spring.

8. Cleaning device according to one or more of Claims 1 to 7, characterised in that in the slot a suction nozzle extending over the sieve band width or slot length is directed on to the sieve belt for the removal of accumulated deposits.

9. Cleaning device as claimed in claim 1, substantially as described herein with reference to and as illustrated by any one of the examples shown in the accompanying drawings.