GB2059454A

GB2059454A - Apparatus for removing an irregularity in a thread

Info

Publication number: GB2059454A
Application number: GB8031326A
Authority: GB
Original assignee: Schubert und Salzer Maschinenfabrik AG
Current assignee: Rieter Ingolstadt Spinnereimaschinenbau AG
Priority date: 1979-09-29
Filing date: 1980-09-29
Publication date: 1981-04-23
Also published as: ES495120A0; DE2939568C2; IT1133627B; PL226345A1; FR2466536A1; DE2939568A1; ES8105046A1; IT8024897A0

Abstract

In a process for effecting a thread join in an open-end spinning machine the thread, in which a join has been spun and which is drawn off from the spinning apparatus, continues to be discharged, the take-up bobbin being stationary until the thread section with the defect is severed in the course of a thread attachment process, whereupon the thread drawn out of the spinning apparatus is wound onto the take-up bobbin. On the appearance of a defect in the thread, the take-up of the latter on to the bobbin is discontinued, and the thread is then discharged in the above- described way. For this purpose the air throughput of a source of low pressure connected to ducts 22, 31 and 41 is controllable and, when the open-end spinning apparatus comes into operation, can be temporarily increased beyond the air throughput required during a normal spinning process. <IMAGE>

Description

SPECIFICATION Apparatus for removing an irregularity in a thread The present invention reiates to an apparatus for removing an irregularity in a thread by means of a thread attachment device on an open-end spinning apparatus, which comprises a spinning chamber and a pneumatic thread removal device which is connected to a source of low pressure which produces the low pressure for spinning.

In order to produce low pressure at various stations of the spinning apparatus, it is known to connect these stations to a common suction line.

If predictable fluctuations in the low pressure occur, an adjustment to the individual stations requiring low pressure is possible by restrictors being more or less open or closed (German Offenlengungsschrift 2,159,120). This, however, is uneconomical and difficult to control.

The object of the present invention is therefore to provide an apparatus which allows, in an economical manner, the production of low pressure during the spinning process and during the time for removal of an irregularity, i.e. as a thread join is spun and thread attachment is carried out.

This object is attained according to the invention by means of an open-end spinning apparatus with a spinning chamber and a pneumatic thread removal (discharge) device, which is connected to a source of low pressure which produces the low pressure for spinning, characterized in that the air throughput of the low pressure source is controllable and when the open-end spinning apparatus is brought into operation it is temporarily increased beyond the air throughput required during normal spinning. In this way the extra air requirement, which is necessary when a thread join is being spun and during the discharge of the thread which then occurs, can be compensated, so that the low pressure conditions also do not alter, in comparison with those occurring during normal spinning, during this time.In this way a constant quality of the thread produced and wound up on the take-up bobbin is achieved in spite of the thread being temporarily pneumatically led off.

When the thread attachment process has been completed at all spinning stations, no further thread must be led off pneumatically. Therefore, according to the invention, the air throughput of the source of low pressure can be reduced, in dependence on switch-off of the thread attachment device, to the air throughput needed during normal spinning. As the thread attachment device is normally assigned a pneumatic thread storage unit which, under certain circumstances, may be constituted by the pneumatic thread discharge device itself, the source of low pressure is, conveniently, assigned a timing member by means of which the reduction in the air throughput occurs, subject to a delay, in dependence on the switch-off of the thread attachment device.The timing member is so set that the thread reserve which has been built up during the thread attachment process is used up in consequence of the tension produced during thread take-up before this reduction in air throughput takes place.

In principle, the control of the air throughput may take place in various ways, for example by altering the speed or by adjusting the fan blades of the source of low pressure. However, it is more economic and therefore more advantageous if the source of low pressure is divided into a main source of low pressure and an auxiliary source of low pressure, by means of which the temporary increase in air throughput is achieved.

The spinning chambers and the thread discharge devices may be connected to a common duct. However, it has been found to be satisfactory if separate ducts are provided for the spinning chambers and for the thread discharge devices.

According to the invention the main source of low pressure and the auxiliary source of low pressure are commonly assigned to two parallel ducts, one of which is used for establishing communication with the spinning chambers and the other of which is used for establishing communication with the pneumatic thread discharge devices.

It is proposed, according to the invention and for the purpose of enabling, when a defect is being individually removed at a single spinning station, draw-off of the thread to occur by means of the low pressure produced by the main source of low pressure, and also for the purpose, when effecting multiple thread joins, of enabling the thread to be drawn off without affecting the low pressure required for spinning, that two parallel duct sections be provided between the main source of low pressure and the duct by means of which communication is established with the spinning chambers, the main source of low pressure being susceptible of being brought alternately into communication with this duct by way of these two parallel duct sections, one of these duct sections comprising a filter by way of which the duct, by means of which communication is established with the thread discharge devices, communicates with the auxiliary source of low pressure, while the other duct section comprises an auxiliary filter.

The two ducts preferably open into the filter at separate points, the filter comprising two separate filter surfaces, one of which is associated with the duct, by means of which communication is established with the spinning chambers, and the other of which filter surfaces is associated with the duct by means of which communication is established with the thread discharge devices. In this way it is possible to cause a separation of dirt, which is removed from the spinning chambers by suction, and pieces of thread which are removed by suction by the thread discharge devices and which can be introduced for re-use. Thus, subsequent contamination of these thread pieces is prevented by these separate filter surfaces.

A valve is provided for cooperation with the duct part which accommodates the filter and enables communication between the duct, which is connected to the spinning chambers, and the filter to be interrupted, and another valve is commonly associated with the two duct parts and alternately interrupts communication between the main source of low pressure and one or the other duct parts. Conveniently, a modification of this particular provision consists in arranging the main filter as a prolongation of the wall of the duct by means of which communication is established with the spinning chambers.As removal by suction by way of the auxiliary filter always only takes place temporarily for the duration of pneumatic thread draw-off, so that not a great deal of dirt accumulates, a small, auxiliary filter of this kind is altogether satisfactory, as this small, auxiliary filter is automatically cleaned, when removal by suction is switched so as to take place by way of the large filter, through the air which sweeps past the surface of the auxiliary filter.

According to a further modification of the invention, and for the purpose of preventing secondary air entering the duct system when the auxiliary source of low pressure is switched off, an auxiliary valve is associated with the auxiliary source of low pressure, and lies on the side of the latter lying remote from the duct part, and permits air throughput when the auxiliary source of low pressure is brought into operation and prevents air flow-through when the auxiliary source of low pressure has been brought out of operation.

Individual closure elements are preferably provided for cooperation with the thread discharge devices and can be opened when the air throughput increases and can be closed when the air throughput decreases. Thus, when multiple thread joins are effected these closure elements free the thread discharge devices only for the duration of the increased air flow-through, which is accommodated to the duration of thread removal. When individual threads are removed the closure element is always merely opened at the relevant spinning station.

The invention is further hereinafter explained by reference to the accompanying drawings, in which: Figure 1 is a schematic side elevation of a spinning station constructed according to the invention; Figure 2 is a schematic view illustrating the mode of operation of the open-end spinning machine constructed in accordance with the invention; Figure 3 is a schematic view of a modification of the subject matter of Figure 2; and Figure 4 is a schematic view of the preferred embodiment of the subject matter of the invention.

It will be assumed, for the sake of simplicity, that the thread attachment device is in the form of a knotting device; however, other thread attachment devices, e.g. twisting devices (DE-OS 1,510,561), can be used in conjunction with the subject matter of the invention.

The invention is described by reference to a conventional open-end spinning apparatus, of which only the parts which are absolutely necessary for understanding the invention are shown. The thread 1 , which in a known manner is produced in a spinning chamber, for example a spinning rotor 2, is drawn from the spinning chamber by a pair of thread draw-off rollers 10, and is passed to a take-up bobbin 11, which is driven by a drive shaft 12 (Figure 1). Associated with the bobbin 11 is a bobbin supporting element 13, by means of which the bobbin 11 can be lifted away from the drive shaft 12.

The spinning rotor 2 occupies a housing 20 which communicates, by way of a tube 21, with a duct 22, which itself communicates with a source (not shown) of low pressure. Positioned in the vicinity of the path of travel of the thread between the draw-off rollers 10 and the bobbin 11 is the mouth 30 of a thread discharge device 3, which communicates with a further duct 31 which, in its turn, communicates with a source of low pressure (not shown).

A thread attachment device 4, which for example comprises a knotter 40, can travel along the open-end spinning machine, and be brought into a position opposite the mouth 30 of the thread discharge device 3. At the side of the knotter 40 remote from the thread discharge device 3 the thread attachment device 4 comprises a thread suction discharge device 41, which communicates with a source (not shown) of low pressure.

In practice there is a tendency to replace the joining points, which are unavoidably formed when effecting a thread join, by other types of thread attachment. For example, the thread joins are cut out, and the thread ends thus formed are ground and twisted; alternatively, a knot is formed in the thread after or during the process of cutting out the thread section which incorporates the joining point. In order to create conditions under which the spinning machine may be brought into operation more quickly, the process of thread attachment is separated in time from that of effecting the thread join. This takes place in the manner hereafter described.

When the open-end spinning machinery is stationary the bobbin is also stationary. For this purpose the bobbin 11 is usually lifted away from the drive shaft 12 by the bobbin supporting element 13. A join is spun in the thread 1 in the usual way, for example by feeding back into the spinning rotor 2 a thread reserve which has previously been formed when the machine was stationary. Following the formation of a join in the thread 1, this thread is drawn out of the spinning rotor 2 by the thread draw-off rollers 10, into whose nip the thread 1 has been inserted in some suitable way. Low pressure is applied to the duct 31, so that the thread situated in front of the mouth 30 of the thread discharge device 3 is sucked into the thread discharge device 3 and into the duct 31; the thread thus sucked into the device 3 and into the duct 31 is in the form of a progressively increasing loop 14 due to the decrease in thread tension between the thread draw-off rollers 10 and the bobbin 1 which is still stationary. This procedure occurs simultaneously at all the spinning stations of an open-end spinning machine. The thread attachment device 4 then travels along the spinning machine and replaces the loop (with its thread joining point 15) by a knot at one spinning station after the other of the machine.For this purpose the apparatus illustrated incorporates, above and below the mouth 30 of the thread discharge device 3, thread guides 42, 43 and 44, and also thread insertion units 45 and 46, by means of which the thread is inserted into the knotter 40 above and below the thread discharge device 3, so that this knotter can knot together the thread loops thus formed. Ths thread loops 14, and the thread waste, formed in the knotting process, are discharged through the thread discharge device 3 and through the thread suction discharge device 31.

The process of removing the thread 1 by means of the thread discharge device 3 thus takes place from the process of forming a thread join up to the thread attachment process, in the course of which the thread loop 14, together with the thread joining point 1 5 which constitutes a thread defect, is severed and is finally removed. When the thread attachment process has concluded, thread take-up is resumed by the bobbin 11 being again released through retraction of the bobbin supporting element 13, so that the bobbin 11 can once again bear against the drive shaft 12, the thread 2 drawn from the spinning rotor 2 being wound on to the take-up bobbin 11.

In the above-described manner the thread attachment device 4 travels along one after the other of the spinning stations for which it is responsible, and replaces the thread loops 14 (together with their thread joining points 1 5) by knots. Meanwhile, the thread 1, in which a join has been formed, is continuously removed, by means of the thread discharge device 3, at the spinning stations which have not yet been serviced, until the thread attachment device 4 commences its work at the spinning station concerned. In this way the thread attachment device 4 is relieved of the preliminary work, which it would otherwise be necessary to perform for effecting a thread join and, accordingly, can execute the thread attachment operation extremely quickly.The saving in time achieved by the way in which all the spinning stations of the open-end spinning machine are thus rapidly brought into operation is so great that the loss in thread, associated with this process in consequence of the fact that the thread is temporarily led away, is altogether negligible.

Also, the lapse in time between the formation of the thread joins and the replacement of the thread join points 1 5 by a thread attachment process enables very simple forms of apparatus to be used, as these procedures, and the apparatus required for carrying out the procedures, do not need to be correlated to one another.

A thread monitoring unit 1 6 is usually positioned between the spinning rotor 2 and the thread draw-off rollers 10. When an irregularity or defect appears in the thread 1, e.g. a thickened or thinner portion in the thread - or when Moor6 is present in the thread, or when there is a thread breakage -- the thread monitoring unit 16, in a known way and by means of control means which are not shown, causes discontinuance of the process whereby the thread 1 is wound up on to the bobbin 11. In the embodiment which is illustrated this is accomplished by lifting the bobbin 11 away from the drive shaft 12 by means of the bobbin supporting element 13.When a thread breakage has occurred, the further process steps are the same as were described above in connection with the production of multiple thread joins.

When there is no thread breakage the thread can be sucked, in the form of a loop 14, into the thread discharge device 3 after the bobbin 11 has been stopped. This loop 14 continues to be formed until, after the irregularity or defect in the thread 1 has passed into the thread discharge device 3, the thread attachment device 4 is brought into operation, and the defect in the thread 1 is removed.

It will be satisfactory if the thread monitoring unit 1 6 produces a thread breakage, on the appearance of a defect, by (for example) discontinuing the feed of fibres into the spinning rotor 2. The operative, whose attention is thus brought to the thread defect, or a suitable automatic device, then cleans the spinning rotor 2 as, in general, a thread defect is attributable to deposits, such as dust, particles of husk, hull and so forth, on the fibre collecting surface of the spinning rotor 2. Also, other working procedures, such as for example the replacement of a spinning rotor 2, may be performed instead of or in addition to the process of cleaning the rotor. A thread join is then formed in the thread 1, and the thread joining point 15 is removed in the abovedescribed way.

When the method is used for effecting multiple thread joins, an appreciable extra air throughput is required whereas, when individual thread joins are effected or when an individual defect is removed in a thread 1 , the air throughput required is insignificant. When multiple thread joins are being effected this requirement for extra air throughput can, according to the invention, be accommodated by arranging for the air throughput of the source of low pressure to be controllable and, when the open-end spinning apparatus is brought into operation, by temporarily increasing the air throughput needed in the case of a normal spinning operation.

An apparatus suitable for thins is shown in Figure 2. The spinning chambers 20 and the thread discharge devices 3 of the individual spinning stations I, Il, Ill, lV,V... open into a common duct 5 which communicates with a source 50 of low pressure. The throughput of the source 50 of low pressure is adjustable: this can, for example, be accomplished by adjusting fan blades (not shown) or by adjusting the speed of the low pressure source 50. The source 50 of low pressure is adjustable by two control devices 51 and 52. The control device 51 controls the whole starting programme and, hence, also the procedure of effecting multiple spin joins when the spinning machine is started up.When the spinning machine is started up the source 50 of low pressure is set to high air throughput; the extra air throughput of the source 50 of low pressure is so selected that, in the case of the individual spinning stations, substantially the same low pressure prevails as during normal spinning operations, when the thread discharge devices 3 are closed.

The thread discharge devices 3 comprise individual closure elements 32 which, in a way which is not illustrated, are adjustable both individually and collectively, in which latter case this control is exercised by way of a linkage 33.

Associated with the linkage 33 is an adjusting or control device 34 which is for example constituted as a magnet and which is commonly actuatable with the source 50 of low pressure. For this reason the adjusting device 34, like the source 50 of low pressure, cannot only be actuated for opening the closure element 32 but also, through the control device 52, for closing the closure element 32.

When it responds to actuation the control device 52 both causes the thread discharge device 3 to be closed, by means of the closure element 32, and also causes the air throughput of the source 50 of low pressure to be reduced to the normal air throughput, i.e. the throughput required when the thread discharge devices 3 are closed.

Accordingly, the control device 52 is actuated when all the thread attachment procedures have been concluded. This may for example take place through the operative actuating a control knob (not shown) when the operative notices that all spinning stations I . . ... . have been serviced by the thread attachment device 4.

Figure 3 illustrates another embodiment of apparatus according to the invention. In the apparatus shown in Figure 3 the source of low pressure is divided into a main source 6 of low pressure and into an auxiliary source 7 of low pressure. The main source 6 of low pressure is used for producing the normal spinning underpressure in the spinning rotors 2 (Figure 1) and also the low pressure required in the thread discharge devices 3 when individual defects are being removed in individual threads 1, that is to say when only one or a few thread discharge devices 3 are open. The auxiliary source 7 of low pressure is used for producing low pressure in the thread discharge devices 3 when multiple thread joins are to be spun.

Again, the control device 51 is provided for cooperation with the auxiliary source 7 of low pressure. In the apparatus shown in Figure 3 the second control device is constituted by the thread attachment device 4 which, by way of a timing member 47, is connected to the auxiliary source 7 of low pressure. In this embodiment also the thread attachment device 4 may be used for controlling the closure element 32 (Figure 2) of the thread discharge devices 3.By means of this form of construction the air throughput can be set to a high value by the control device 51 when the machine is switched on through switching the auxiliary source 7 of low pressure to a high value, and the air throughput can be set to the normal value as a result of the thread attachment device 4 being switched off, the auxiliary source 7 of low pressure, which was brought into operation when the spinning programme started, now being brought out of operation.

As the thread 1 normally has to be immobilized when subjected to a thread attachment procedure, it is normal practice to provide a pneumatic thread storage unit in the path of thread travel between the draw-off rollers 10 (Figure 1) and the thread attachment device 4. If the thread guide 42 and the thread insertion unit 45 are suitably constructed and arranged the thread discharge device 3 can also perform the role of a thread storage unit of this kind. The length of thread stored during the procedure of effecting thread attachment must, when the thread attachment procedure has ended, be taken up by the resumption of winding the thread onto the take-up bobbin; the stored length of thread must be kept in a tensioned state.The time needed for this is preset in the timing member 47, so that the auxiliary source 7 of low pressure is brought out of operation by the thread attachment device 4 subject to a suitable delay time.

The main source 6 of low pressure and the auxiliary source 7 of low pressure may replace the source 50 of low pressure shown in Figure 2 and communicate with a single duct 5, into which open both the ducts 21 of the housings 20 and also the thread discharge devices 3. However, it is more advantageous to provide two separate ducts 22 and 31, as will be shown in the following description.

As shown in Figure 3, two parallel duct sections 60 and 61 are provided between the main source 6 of low pressure and the duct 22 with which the housings 20, accommodating the spinning rotors 2, communicate. A valve 62 is provided at the branch nearest to the duct 22 and in one of its positions cuts off the duct section 61 and establishes communication between the duct section 60 and the duct 22 and, in its other terminal position, cuts off the duct section 60 and establishes communication between the duct section 61 and the duct 22. The valve 62 can be controlled by means of a magnet 63 which is connected, for control purposes, to the control device 51 and to the timing member 47.

The duct 31 opens into the duct section 60 and communicates with the thread discharge devices 3. Further, another duct 70 opens into the duct section 60 between the mouth of the duct 31 and the main source 6 of low pressure; the auxiliary source 7 of low pressure communicates with this duct 70. At the point at which the duct 70 opens into the duct section 60 there is arranged a valve 71 which, in one of its positions, cuts off the duct 70 and establishes communication between the duct 31 and the main source 6 of low pressure and, in its other position, frees the mouth of the duct 70 and discontinues communication between the duct 31 and the source 6 of low pressure. The valve 71 is adjustable by means of a magnet 72 which, like the magnet 63, can be acted on by the control device 51 and by the timing member 47.

A filter 64 is arranged in the duct section 60 between the two mouths of the ducts 31 and 70.

The duct section 61 also has an auxiliary filter 65.

When the machine is started up, the valves 62 and 71 are brought, by way of the control device 51 , from the positions illustrated into the positions shown in dashed lines. At the same time the main source 6 of low pressure and the auxiliary source 7 of low pressure are brought into operation. The suction air stream, which produces the low pressure required in the housings 20, for spinning, passes - by way of the duct 22 and the duct section 61 (with the auxiliary filter 65)-to the main source 6 of low pressure, impurities contained in the suction air stream being retained in the auxiliary filter 65.At the same time air is sucked by the auxiliary source 7 of low pressure through the thread discharge devices 3, which were opened in the course of the starting programme, this air passing by way of the duct 31, the duct section 60 (with filter 64) and the duct 70. The procedures for effecting a thread join and thread attachment, with simultaneous removal of defects, constituted by the thread joining points 1 5 (Figure 1), then take place in the above-described manner. When the thread attachment procedures have been completed at all the spinning stations, and when the thread attachment device 4 has been stopped, the thread attachment device 4 delivers a pulse to the timing member 47 which, after a lapse of the set delay time, closes off the thread discharge device 3 and cuts out the auxiliary source 7 of low pressure.At the same time the valves 62 and 71 are moved back from their positions shown in dashed lines to their starting or basic positions, illustrated in the drawing. Thus the duct section 61 is isolated from the duct 22, and the suction air stream, which produces the underpressure required for spinning, then passes along the duct section 60.

In this position of the valves 62 and 71, a defect in the thread is also removed at individual spinning stations I . ... . , the corresponding thread discharge device 3 being freed for air flow by actuating the relevant closure element 32 (Figure 1).

A single magnet can be used instead of two magnets 63 and 72, in which case the two valves 62 and 71 will be connected to one another in some suitable way. One or more other drive devices, e.g. pneumatic cylinders, may be used instead of one or more magnets.

As Figure 4 shows, the duct 31 may also open into the duct section 60 in the vicinity of the filter 64. In order to enable uncontaminated sections of thread, which reach the filter 64 through the duct 31, to be introduced for re-use, the filter 64 has two separate filter surfaces 66 and 67 (Figure 4).

The filter surface 66 is associated with the duct 22, by means of which communication is established with the housings 20, and the filter surface 67 is associated with the duct 31, by means of which communication is established with the thread discharge devices 3. Accordingly, the dirt accumulates on the filtering surface 66, while the thread sections collect on the filter surface 67.

Figure 4 shows an embodiment which differs from that of Figure 3 in the mode of construction adopted for alternatively establishing communication of the main source 6 of low pressure and the duct sections 60 and 61. Thus, while in the case of the embodiment of Figure 3 switchover to one or the other duct parts 60 or 61 takes place at their ends nearest the duct 22, in the case of the embodiment of Figure 4 the valve 8, by means of which switchover occurs, is positioned at the ends of the duct sections 60 and 61 lying nearest the main source 6 of low pressure. Again, a magnet 80 is associated with the valve 8. Also, a valve 9, which either frees the duct section 60 for air flow or closes off the duct section 60 for air flow, lies at the end of the duct section 60 nearest the duct 22. A magnet 90 is also assigned to this valve 9.The two magnets 80 and 90 are controlled by a control device 51 and, with the interposition of a timing member 47, by the thread attachment device 4 in a way similar to that described in connection with the magnets 63 and 72 (Figure 3). When multiple thread joins are spun, the main source 6 of low pressure and the auxiliary source 7 of low pressure are brought into operation by the control device 51, and the valves 8 and 9 brought into the positions shown in dashed lines. The spinning underpressure produced by the main source 6 of low pressure, is applied to the housings 20 by way of the duct section 61 and the duct 22, while the low pressure produced by the auxiliary source 7 of low pressure is applied to the thread discharge devices 3 by way of the duct 70, the duct section 60 and the duct 31.When the thread attachment procedures have been completed, the thread attachment device 4 causes the main source 7 of low pressure to be switched off and the valves 8 and 9 to be switched over into their positions represented by continuous lines. The stream of.

suctioned air which produces the low pressure required for spinning then passes from duct 22 to the main source 6 of low pressure by way of the duct section 60, while there is no air stream flowing through the duct section 61. The stream of suctioned air flowing in the duct 31 suffices to produce the low pressure needed for the individual removal of thread defects in the individual thread discharge devices 3.

In order, during normal spinning operations and when the auxiliary source 7 of low pressure has been off, to prevent secondary air passing into the duct section 60 through the auxiliary source 7 of low pressure and through the duct 70, which would reduce the efficiency of the source 6 of low pressure, an auxiliary valve 73 is arranged, as can be seen in Figure 4, on the side of the auxiliary source 7 of low pressure lying remote from the duct section 60. This auxiliary valve 73 is so constituted that it allows through passage of air when the auxiliary source 7 of low pressure has been switched on, while it prevents through passage of air when the auxiliary source 7 of low pressure has been switched off.This may be accomplished in a simple way if the auxiliary valve 72 is constituted as a hingedly swivellable valve which, when the auxiliary source 7 of low pressure is inoperative, bears against a seating 74 subject to gravity or to a biasing force (e.g. a spring), while this swivellable valve can be lifted away from its seating 74 through the condition of relatively high pressure which is effective on the side of the duct when the auxiliary source 7 of low pressure is operative. The duct 70 may be sealed off more effectively still if the duct section 60 and, accordingly, also the duct 70, are subject to low pressure. Thus, any penetration of air is satisfactorily prevented when the auxiliary source 7 of low pressure is inoperative, whereas the air can discharge when the source 7 of low pressure is operative.

It is advantageous -- in the case of the embodiment of the invention illustrated in Figure 4, in which communication between the duct section 60 with the filter 64 and the housings 20, which accommodate the spinning rotors 2, can be interrupted by means of the valve 9, and in which switchoverto one of the duct sections 60 or 61 takes place through a valve 8 at the other end of the duct sections 60 and 61 - if the auxiliary filter is not, as shown in Figure 3, arranged somewhere in the duct section 61. Instead an auxiliary filter 68 is arranged as a continuation of the wall 23 of the duct 22.This auxiliary filter 68 is indeed small in the case of this form of construction; however, it does suffice to clean the air sucked into the main source 6 of low pressure, so long as the procedures of effecting multiple thread joins and of effecting thread attachment continue. When, later, the air stream is again led over the duct section 60, the air stream travels over the surface of the auxiliary filter 68 and entrains the contaminants which have been deposited on this surface, so that the auxiliary filter in this way is again automatically cleaned.

The invention does not only include the embodiments illustrated and explained but other embodiments in which individual features are replaced by equivalent features or which are combined with one another in some different way.

Aiso, the source 50, 6 or 7 of low pressure does not have to be positioned in the open-end spinning machine itself, but can be separately disposed and assigned to a number of spinning machines. When this provision is adopted it is also feasible if the main source 6 of low pressure and/or the auxiliary source 7 of low pressure consist of a number of individual units, which are individually controllable so that accommodation can be made to the number of machines dependent on these individual units and in dependence on the number of these machines in which the procedures of effecting multiple thread joins and effecting thread attachment take place.

The air throughput of the sources of low pressure may be controllable, or it may be simply possible to switch these sources of low pressure on or off.

Naturally, the thread discharge devices 3 may comprise closure elements 32 which are only adjustable by hand. Insofar as the process of effecting multiple thread joins is concerned it is however advantageous if these individually adjustable closure elements 43 are additionally commonly controllable with the alteration of the air throughput, the closure elements 43 freeing the thread discharge devices 3 when an increased air throughput is adopted at the start of the process of effecting multiple thread joins, and once again closing off the thread discharge devices 3 when the air throughput is again reduced when the thread attachment procedures have been completed. Aiso, the control device 34 can be actuated, for bringing individual closure elements 32 from their opening into their closing position after each individual removal of a defect in the thread 1.

Switchover from duct section 60 to duct section 61 is mainly used for enabling the low pressure, required for spinning, in the housings 20, and the low pressure in the thread discharge devices 3, to be controlled independently of one another. However, this apparatus also enables the filter 64 to be cleaned when the machine is running. For this purpose, in an apparatus of the kind shown in Figure 3 or in Figure 4, the suctioned air stream, which produces the low pressure required for spinning, is led through duct section 61 without the auxiliary source 7 of low pressure being brought into operation.

Accordingly, no air stream flows through the filter 64, so that the filter 64 can be cleaned. After conclusion of the filter cleaning process the air stream, which produces the low pressure required for spinning, is again led through the duct section 60.

Naturally, the cleaning of filter 64 can also happen automatically by reversing the air stream or air streams. For this purpose a duct which communicates with another source (not shown) of low pressure opens into the duct section 60 between the valve 62 (Figure 3) and filter 64; a state of low pressure is produced in this duct after the duct section 60 has been cut of of the system.

Similarly, a cleaning duct of this kind can, in the case of the embodiment shown in Figure 4, open into the duct section 60 between the filter 64 and the valve 9, and a further cleaning duct can open into the duct 31.

Also, it is not absolutely mandatory that the low pressure, required for spinning, be produced in a housing 20 which surrounds the spinning rotor 2.

The ambit of the present invention includes a provision whereby the low pressure is applied, from outside, to the spinning rotor 2 in some other way, e.g. through a cover or top, which covers off the spinning rotor 2, or through the rotor shaft.

Claims

1. Apparatus for removing a defect in a thread by means of a thread attachment device in an open-end spinning apparatus, which comprises a spinning chamber and a pneumatic thread discharge device, which communicates with the source of low pressure which produces the low pressure required for spinning, characterized in that the air throughput of the source of low pressure is controllable and, when the open-end spinning apparatus comes into operation, can be temporarily increased beyond the air throughput required during a normal spinning process.

2. Apparatus according to Claim 1, wherein the air throughput, in dependence on switch-off of the thread attachment device, can be reduced to the air throughput required during a normal spinning process.

3. Apparatus according to Claim 2, wherein a timing member is associated with the source of low pressure and, by means of this timing member, the reduction of the air throughput takes place in dependence on switch-off of the thread attachment device.

4. Apparatus according to any of Claims 1 to 3, wherein the source of low pressure is divided into a main source of low pressure and an auxiliary source of low pressure, by means of which the temporary increase in the air throughput takes place.

5. Apparatus according to Claim 4, wherein the main source of low pressure and the auxiliary source of low pressure are commonly assigned to two parallel ducts, one of which ducts is used for establishing communication with the spinning chambers, and the other of which ducts is used for establishing communication with the pneumatic thread discharge devices.

6. Apparatus according to Claim 5, wherein two parallel duct sections are provided between the main source of low pressure and the duct, by means of which communication is established with the spinning chambers, by means of which duct sections the main source of low pressure can be brought into alternate communication with this duct; one of these duct sections comprising a filter by means of which the duct, by which communication is established with the thread discharge devices, communicates with the auxiliary source of low pressure, whereas the other duct section comprises an auxiliary filter.

7. Apparatus according to Claim 6, wherein the filter comprises two separate filter surfaces, of which one is associated with the duct, by means of which communication is established with the spinning chambers, and of which the other filtering surface is associated with the duct by means of which communication is established with the thread discharge device.

8. Apparatus according to Claim 6 or Claim 7, wherein the duct section, which accommodates the filter, is assigned a valve by means of which communication can be discontinued between the duct, by means of which communication is established with the spinning chambers, and the filter, and the two duct sections are commonly assigned a valve which alternately interrupts communication between the main source of low pressure and one or the other duct sections.

9. Apparatus according to any of Claims 6 to 8, wherein the auxiliary filter is in the form of a prolongation of the wall of the duct by means of which communication is established with the spinning chambers.

10. Apparatus according to Claim 8 or Claim 9, wherein the auxiliary source of low pressure, on the side lying remote from the duct section, is assigned an auxiliary valve which permits air flow through when the auxiliary source of low pressure is brought into operation and which prevents air flow-through when the auxiliary source of low pressure is brought out of operation.

11. Apparatus according to any of Claims 1 to 10, wherein the thread discharge devices are assigned individual closure elements which can be opened when the air throughput increases and can be closed when the air throughput decreases.

12. Apparatus for performing a method according to any of the preceding claims substantially as hereinbefore described with reference to, and as shown in, any of the accompanying Figures or drawings.