Title of Invention	A DOUBLE --APRON DEAFTING SYSTEM FOR SPINNING MACHINERY AND A METHOD FOR CLEANING THE AIR-FLOW PATHS OF A PNEUMATIC CONDENSER DEVICE
Abstract	The present invention provides a double-apron drafting system for spii]iiin<_' machinery, comprising a fibre bunching zone which joins the pair of front lollcis of the main drafting zone and is followed by a delivery device wherein a pncumauc condenser device is arranged between the pair of front rollers and the dclivci v dc\ uc that has a perforated apron and a suction device which is configured as a api'on ^\\\x and extends on the apron side facing away from the fibre structure (FS) and draw sin air through the fibre structure, characterized in that a blow air line (45) has iis iiu)uili opposite the mouth of the suction air line in the apron cage formed as a housing, I he present invention also relates to a method for cleaning the air-flow paths o\' a pneumatic condenser device which is arranged in the fibre bunching zone of the said system.

Title of Invention

A DOUBLE --APRON DEAFTING SYSTEM FOR SPINNING MACHINERY AND A METHOD FOR CLEANING THE AIR-FLOW PATHS OF A PNEUMATIC CONDENSER DEVICE

Abstract

The present invention provides a double-apron drafting system for spii]iiin<_' machinery, comprising a fibre bunching zone which joins the pair of front lollcis of the main drafting zone and is followed by a delivery device wherein a pncumauc condenser device is arranged between the pair of front rollers and the dclivci v dc\ uc that has a perforated apron and a suction device which is configured as a api'on ^\\\x and extends on the apron side facing away from the fibre structure (FS) and draw sin air through the fibre structure, characterized in that a blow air line (45) has iis iiu)uili opposite the mouth of the suction air line in the apron cage formed as a housing, I he present invention also relates to a method for cleaning the air-flow paths o\' a pneumatic condenser device which is arranged in the fibre bunching zone of the said system.

Full Text	DRAFTING EQUIPMENT WITH SMALL DOUBLE BELTS The invention relates to drafimg equipment with small double belts for spinning machines \vith a fiber bundling zone which follows the pair of output rollers and is followed by the pair of delivery rollers according to the introductory clause of claim L Drafting equipment of this type is described in DE 43 23 472. Therein a pneumatic compression device is installed between the pair of output rollers and the pair of delivery rollers, said conpression device being provided with a small perforated belt and a suction device extending on the side of the small belt away £rom the fiber sliver and aspiring air through he fiber sliver. Very good results are achieved with this known device with respect of gathering together and bundling of the fibers, so that a smooth yam with considerably improved resistance to tearing is spun. It was shown however that the pneumatic compression device has relatively high air consumption. When using the conventional traversing apparatus it may furthermore occur tliat border fibers are no longer seized securely because they are either outside the perforation, or because the negative pressure is not sufficiently strong to bundle them. An erilargement of the perforation not only requires more air but decreases the gathering together of the fibers. Increased negative pressure also required more suction capacity. It is however also important for the obtention of ftniform spinning results that the optimal state of the drafting equipment, in particuiai of the compression device, be maintained.. In the known device a small belt is used without &tHic insert in order to release the fibers at the outlet of the delivery roller which had been sucked into the perforation by their ends. These small belts without fabric inserts do not last long. It is the object of the present invention to avoid the described disadvantages and to improve the compression effect of the known device vAule reducing the suction capacity. The invention is based on the recognition of the fact that orify a relath/ely short distance is necessary for the bundling of the fiber sliver, and this independently of the staple length of the fibers. The maintenance of the suction air stream as far as into the area of the nip of the delivery Cylinder merely serves to maintain the bundling of the fiber sliver up to the entry into the pair of delivery cylinders. According to the invention the problem is solved by the characteristics of claims 1,6, 11, 18 and 23 separatety or in combination with each other, The shortening of the suction zone (claim 1) results in considerably reduced air consumption and heightened conpression efiect. Fibers which may have been diverted during transportation are again bundled by fiirther compression in the immediately area before the entry of the fiber sliver into the nip of the delivery cylinder. By connecting the perforation openings by one or several grooves (ciaim 6) a mechanical holding of the bundled fibers is achieved so that the fibers are kept in their bundled position even without suction effect. Furthermore by providing several grooves, the small belts can be used universally with fiber slivers of di&rent thicknesses. By using perforation openings with dimensions perpendicular to the direction of fiber movement greater than in the direction of fiber movement (claim I \\ the fiber sliver is safety brought together also during traversing. A certain rough gathering together results, so that the perforation can be kept smaller fi)r the actual compression and so that not only savings in air, but also a closer gathering together of the roving is achieved. In order to always maintain the effect of the pneumatic compression device at an optimal level, it has proved to be necessary to clean it fi^om time to time. This is especially necessary with a lowered negative pressure. This can be carried out easily by the device according to claim 18 Hiis embodiment makes also automation, e.g. in connection with thread piecing, possible. Finally, according to the characteristics of claims 15 and 16, small belts Avith long life can be used and reliable release of fibers caught at the outlet fi'om the delivery cylinder can nevertheless be achieved. The characteristics of claim 23 make it possible to avoid a clogging of the perforation by dust etc, and thereby to avoid lowering of the optimal suction effect. Further details of the invention are described through the drawings, Figs. 1 and 2 show a small belt with a groove, in a top view and cross-section; Figs. 3 and 4 show dif&rent embodiments of the small belt with transversal holes, with and without grooves; Fig. 5 shows an embodiment with a groove to lifl off the small belt; Fig. 6 shows an embodiment with shortened suction zone and additional compression; Figs. 7 and 8 show details of Fig. 6 seen fi^om below and in cross-section; Figs. 9 anbl 0 show an embodiment with cleaning device in lateral view and fi'om above; Figs. 11 and 12 show an embodiment of the conq)ression device with two alternately usable perforations. Drailtjig equipment ^h double belts for spinning machines Avith a £ber bundling zone following the pair of output rollers of the main drafting field and Avhich is followed by the pair of delivery rollers 5 has already been described completely in DE 43 23 472, so that only the improvements according to the invention of this drafting equipment are discussed below. Fig. 1 shows the small belt 6 of the pneumatic conpression device which is provided with perforations 61, hereinafter compression holes 61, which are connected to teach other by a groove 62. The groove 62 is drawn greatly enlarged. It is adapted in its width to the mass of fibers to be gathered together by the compression holes 61, The gathered fibers come to lie in the groove 62 which is sized so that it exerts a certain clamping effect on the fibers. As a result the bundled fibers are held mechanically until the are under the nip of the delivery roller 5 so thai the suction air stream need be shut off only on the bundling immediately after emergence fi^om tfie pair of output rollers F.O. the drafting equipment. Figs. 1 and 2 show only one groove 62 wiiich connects the compression holes 61 with each other. However several grooves 62, e.g. three, are advantageously placed parallel to each other Even when more grooves are used, these are always in the area of the compression holes 61, never further out. The width of these grooves 62 is kept so that they are just able to accept the mass of fibers, so that a certain clanging action results. It has been found that several grooves 62, eg three (Fig. 4) are better than only one single groove 62, because the small belt 6 can be used more umversally. With very fine yams one single groove 62 would be too wide and would not exert any clamping action, and on the other hand too narrow a groove 62 would not be able to receive the mass of thicker yams. If several grooves 62 are used, e.g. three, the fiber mass only enters tlie central groove for finer yams. The outer grooves remain empty. In this manner sufficient clamping action is achieved however. The grooves 62 are fiirthenmore placed symmetrically with respect to the area of the compression holes 61. Figs. 3 and 4 show small belt 6, 600 where in addition to the conpression holes 61, perforation openings 63 are shown, extending fiirther in the direction across the direction of fiber movement than in the direction of fiber movement. By means of these so-called transversal holes 63 the compression device is able to achieve rough compression of especially wide fiber slivers Furthermore the fibers are still bundled by these transversal holes 63 when the position of the fiber sliver altemates as a result of traversing movement. Gathering together over a greater width results. The transversal extension of these transversal holes 63 therefore is approximately equal to the traversing stroke or to the therety changed position of the fiber sliver relative to the small belt 6, Transversal holes 63 and compression holes 61 are placed in regular ahemation. With the small belt 60 in Fig. 3. a transversal hole is alw^s placed between two compression holes. For air consurrytion it is however more advantageous if the number of transversal holes 63 is smaller than the number of compression holes 61. For instance in Fig. 4, with the smaJJ belt 600, one transversal hole 63 follows every two compression holes 61. In this manner, good compression is achieved with less air consumption and traversing of the liber sliver. Comprehensive tests have shown that the gathering together of the fiber sliver by the suction air stream, transversally to the conveying direction, begins immediate^ upon emergence from the pair of output rollers, but ends after a short distance. This gathering together is independent of the staple length. Suitable design of the perforation as described above is furthermore favorable for the gathering together. It has been shown that the suction zone defined by the groove 41 need not to extend as far as the delivery cylinder 5. Shortening the suction zone fiirthermore increases the effect of the suction air stream in the shortened area and thereby increases the gathering together of the fiber sliver. Shortening the suction zone even allows for considerable reduction of the suction capacity Wiile the bundling eSect remains the same. Fig. 6 shows an embodiment in which the groove 41 in the belt cage 4 extends only over less than one half of the length of the belt cage 4. The groove 41 \^4iich is connected to the suction channel 42 is located in the portion of the belt cage 4 which is away from the deliveiy cylinder 5 and is open towards the output cylinder of the drafting equipment. The length of this suction zone is approximately 10 to 25 mm. In this short zone the fiber sliver is already gathered together completely. The suction zone can therefore be kept as short as possible to save suction air capacity, i.e. it is orify as long as is absolutely necessary for the gathering together of the iibers With long fiber staples the width of the cylinder nip is greater in fiinction of the staple length. In that case too, the suction zone may not be greater. Following the suction zone, the grooves 62 in the small belt 6 then possibly assume the cohesion or the clamping of the fibers gathered together, as described earlier. In addition, subsequent conpression may also take place between the suction zone defined by groove 431 and the nip of the delivery cylinder 5. For this purpose a channel 43 is provided which connects the groove 41 to the subsequent compression are before the delivery cylinder 5. Figs. 11 and 12 show an alternative embodiment of the compression device, in which two perforations 61 and 61' as well as 63 and 63' are provided. At the perforation 61', 63', the perforation openings are additionally connected to the grooves 62, The variants according to Figs 3 and 4 are combined here, but due to the asymmetrical placement of the groove 410 in the belt cage 40, always only one of the perforation rows is operating at a time. The groove 410 is connected via a suction channel 420 to the exhaust suction which is not showa This embodiment has the advantage that the compression device can easily be adapted to different roving thicknesses and material requirements by turning over the small beh 660. The small belt 660 is thereby more flexible in its application than a belt with only one row of pedbratioas. D£ 43 23 472 describes that as a result of the suction air stream it happens that fiber ends are sucked through the perforation and are then caught between the small belt 6 and the upper roller S. This leads to annoying interference during spinning because these fibers are unable to follow the direction of the fiber sliver being twisted into a yam. It is therefore desirable to lift the belt6 from the delivery cylinder 6 in the output area in order to prevent this clamping of the fibers In the above-mentioned DE 43 23 472 this lifting of the belt 6 is effected through suitable selection of the belt material. A lifting eflfect can however be also achieved by providing a groove mt he delivery cylinder 5 under the perforation, so that the belt 6 does not lie on the delivery cylinder 5 at that location. These measures require however special design of the delivery cylinder 5 or also of the belt 6. Furthermore the belt 6 is less resistant to wear if it lacks a fabric layer. According to the present invention, a free space is created in the run-out of the delivery cylinder 5 by providing a ridge 2 Over \Adch the belt 6 is guided immediately following the nip of the delivery cylinder 5. The ridge 2 is attached to a holder 21, The ridge 2 is adjustable by adjusting this holder 21. Tlus ridge 2 not only serves to create clearance to prevent the catching of the fibem, but thatiki to the more pronoxmeed deflection of the belt 6, the fibers are more easily detached frf m the belt 6, especially v^en fine yams are spua Peeling of the fibers is avoided in any case, thus resulting in better and more unifonm yam quality. If the suction is operating for a long period of time in the fiber bundling zone, an accumulniion of fiber fly and dust in the groove 41 cannot be avoided, so that the operation of the pneumatic conqjression device is gradually affected. The traveling blowers nomially used with ring spinning machines cannot be used for satisfactory cleaning in this case because they are only externally effective. Disassembly for cleaning of the pneumatic compression device is however very expensive. Figs 9 andlO show an embodiment in which a cleaning device for the conpression device is provided. A blowing air diannel 45 with a connection piece 44 lets out in the belt cage 4 info the groove 41 across from the outlet of the suction air channel 42. If cleaning is to be carried out, compressed air is introduced through this blowing air channel 45, while the negative pressure through the suction air channel 42 is however maintained. It has been shown that the dirt which settles generally in the groove 41 and especially at the outlet of the suction channel 42 can be successfiilfy removed in this manner. The compressed air is conveyed to the connection piece 44. This can be done manuaUy but also by means of an automatic traveling carriage. In the arrangement of Fig. 10 two con^ression devices are attached in a pair to a carrier which in turn is held in the conventional bearing ami of the drafting equipment on which the upper roller pair of the delivery cylinder 5 is also mounted in the center. To avoid the necessity for the service carriage to recognize in each instance whether the spinning station involved is on the right or on the left side of the bearing ann of the^draflmg equipment, the connection pieces 44 and 44* are given identical positions relative to the spinning station. Cleaning advantageously takes place m conjunction with yam breakage repair. When the service carriage is positioned at a spinning station, the identical placement of the connection piece 44 or 44' relative to the spindle ensures that the service carriage ensures that it is able to service the connection piece 44 or 44' without making a distinction. The cleaning device thus not only carries out successful cleaning of the compression device but furthermore can be easily operated by a service carnage. Reduction of the suction e£^t can occur as a result of dust settling in the perforation. AJso burrs at the edge of the perforation can cause fibers to get caught on them It has been shown that a debarred perforation operates without problems and without clogging even when the material is very dirty. Such a burr-free perforation is obtained by breaking the edges which have normally bum as a result of the usual punching process. It is more economical and sin^ler in production to make the perforation by means of a laser ray. With this production process clean and burr-free perforations are produced, and these surprisingly have no tendency to be clogged by dust or catching fibers. REFERENCE LIST 2 Ridge 21 Ridge holder 3 Carrier 4,40 Belt cage 5 Delivery roller 41,410 Groove 42,42', 420 Suction channel 43 Channel 44,44* Connection piece 45 Blown-air channel 6, 60,600, 660 Small belt 61, 61* Compression holes, perforation openings 62 Groove * • 63, 63' Transversal holes, perforation openings 1. A double-apron drafting system for spinning machinery, comprising a fibre bunching zone which joins the pair of front rollers of the main drafting zone and is followed by a delivery device (5) wherein a pneumatic condenser device is arranged between the pair of front rollers and the delivery device (5) that has a perforated apron (6) and a suction device which is configured as a apron cage (4) and extends on the apron side facing away from the fibre structure (FS) and draws in air through the fibre structure, characterized in that a^blow air line (45) has its mouth opposite the mouth of the suction air line (42, 42) in the apron cage (4) formed as a housing. 2. The device according to claim 1, characterized in that a connecting sleeve (44, 44) is provided at each spinning position to feed blow air thereto. 3. The device according to according to one of claim 1 or 2, characterized in that the connecting sleeve (44, 44') is arranged at each spinning position in the same way each with respect to the spinning position. 4. A method for cleaning the air-flow paths of a pneumatic condenser device which is arranged in the fibre bunching zone of a double-apron drafting system for spinning machinery following the pair of front rollers of the main drafting zone and has a suction device which draws in air through the completely drawn fibre structure (FB) that requires condensing, characterized in that compressed air for cleaning is led into the suction device (4) with the negative pressure, however, being maintained at the same time. 5. A double-apron drafting system for spinning machinery substantially as herein described with reference to the accompanying drawings. 6.A method for cleaning the air-flow paths of a pneumatic condenser device which is arranged in the fibre bunching zone of a double-apron drafting system substantially as herein described with reference to the accompanying drawings.

Full Text

DRAFTING EQUIPMENT WITH SMALL DOUBLE BELTS
The invention relates to drafimg equipment with small double belts for spinning machines \vith a fiber bundling zone which follows the pair of output rollers and is followed by the pair of delivery rollers according to the introductory clause of claim L Drafting equipment of this type is described in DE 43 23 472. Therein a pneumatic compression device is installed between the pair of output rollers and the pair of delivery rollers, said conpression device being provided with a small perforated belt and a suction device extending on the side of the small belt away £rom the fiber sliver and aspiring air through he fiber sliver.
Very good results are achieved with this known device with respect of gathering together and bundling of the fibers, so that a smooth yam with considerably improved resistance to tearing is spun. It was shown however that the pneumatic compression device has relatively high air consumption. When using the conventional traversing apparatus it may furthermore occur tliat border fibers are no longer seized securely because they are either outside the perforation, or because the negative pressure is not sufficiently strong to bundle them. An erilargement of the perforation not only requires more air but decreases the gathering together of the fibers. Increased negative pressure also required more suction capacity. It is however also important for the obtention of ftniform spinning results that the optimal state of the drafting equipment, in particuiai of the compression device, be maintained..
In the known device a small belt is used without &tHic insert in order to release the fibers at the outlet of the delivery roller which had been sucked into the perforation by their ends. These small belts without fabric inserts do not last long.
It is the object of the present invention to avoid the described disadvantages and to improve the compression effect of the known device vAule reducing the suction capacity.
The invention is based on the recognition of the fact that orify a relath/ely short distance is necessary for the bundling of the fiber sliver, and this independently of the staple length of the fibers. The maintenance of the suction air stream as far as into the area of the nip of the delivery Cylinder merely serves to maintain the bundling of the fiber sliver up to the entry into the pair of delivery cylinders.
According to the invention the problem is solved by the characteristics of claims 1,6, 11, 18 and 23 separatety or in combination with each other,
The shortening of the suction zone (claim 1) results in considerably reduced air consumption and heightened conpression efiect. Fibers which may have been diverted during transportation are again bundled by fiirther compression in the immediately area before the entry of the fiber sliver

into the nip of the delivery cylinder.
By connecting the perforation openings by one or several grooves (ciaim 6) a mechanical holding of the bundled fibers is achieved so that the fibers are kept in their bundled position even without suction effect. Furthermore by providing several grooves, the small belts can be used universally with fiber slivers of di&rent thicknesses.
By using perforation openings with dimensions perpendicular to the direction of fiber movement greater than in the direction of fiber movement (claim I \\ the fiber sliver is safety brought together also during traversing. A certain rough gathering together results, so that the perforation can be kept smaller fi)r the actual compression and so that not only savings in air, but also a closer gathering together of the roving is achieved.
In order to always maintain the effect of the pneumatic compression device at an optimal level, it has proved to be necessary to clean it fi^om time to time. This is especially necessary with a lowered negative pressure. This can be carried out easily by the device according to claim 18 Hiis embodiment makes also automation, e.g. in connection with thread piecing, possible. Finally, according to the characteristics of claims 15 and 16, small belts Avith long life can be used and reliable release of fibers caught at the outlet fi'om the delivery cylinder can nevertheless be achieved.
The characteristics of claim 23 make it possible to avoid a clogging of the perforation by dust etc, and thereby to avoid lowering of the optimal suction effect.
Further details of the invention are described through the drawings,
Figs. 1 and 2 show a small belt with a groove, in a top view and cross-section;
Figs. 3 and 4 show dif&rent embodiments of the small belt with transversal holes, with and
without grooves;
Fig. 5 shows an embodiment with a groove to lifl off the small belt;
Fig. 6 shows an embodiment with shortened suction zone and additional compression;
Figs. 7 and 8 show details of Fig. 6 seen fi^om below and in cross-section;
Figs. 9 anbl 0 show an embodiment with cleaning device in lateral view and fi'om above;
Figs. 11 and 12 show an embodiment of the conq)ression device with two alternately usable

perforations.
Drailtjig equipment ^h double belts for spinning machines Avith a £ber bundling zone following the pair of output rollers of the main drafting field and Avhich is followed by the pair of delivery rollers 5 has already been described completely in DE 43 23 472, so that only the improvements according to the invention of this drafting equipment are discussed below.
Fig. 1 shows the small belt 6 of the pneumatic conpression device which is provided with perforations 61, hereinafter compression holes 61, which are connected to teach other by a groove 62. The groove 62 is drawn greatly enlarged. It is adapted in its width to the mass of fibers to be gathered together by the compression holes 61, The gathered fibers come to lie in the groove 62 which is sized so that it exerts a certain clamping effect on the fibers. As a result the bundled fibers are held mechanically until the are under the nip of the delivery roller 5 so thai the suction air stream need be shut off only on the bundling immediately after emergence fi^om tfie pair of output rollers F.O. the drafting equipment.
Figs. 1 and 2 show only one groove 62 wiiich connects the compression holes 61 with each other. However several grooves 62, e.g. three, are advantageously placed parallel to each other Even when more grooves are used, these are always in the area of the compression holes 61, never further out. The width of these grooves 62 is kept so that they are just able to accept the mass of fibers, so that a certain clanging action results. It has been found that several grooves 62, eg three (Fig. 4) are better than only one single groove 62, because the small belt 6 can be used more umversally. With very fine yams one single groove 62 would be too wide and would not exert any clamping action, and on the other hand too narrow a groove 62 would not be able to receive the mass of thicker yams. If several grooves 62 are used, e.g. three, the fiber mass only enters tlie central groove for finer yams. The outer grooves remain empty. In this manner sufficient clamping action is achieved however. The grooves 62 are fiirthenmore placed symmetrically with respect to the area of the compression holes 61.
Figs. 3 and 4 show small belt 6, 600 where in addition to the conpression holes 61, perforation openings 63 are shown, extending fiirther in the direction across the direction of fiber movement than in the direction of fiber movement. By means of these so-called transversal holes 63 the compression device is able to achieve rough compression of especially wide fiber slivers Furthermore the fibers are still bundled by these transversal holes 63 when the position of the fiber sliver altemates as a result of traversing movement. Gathering together over a greater width results. The transversal extension of these transversal holes 63 therefore is approximately equal to the traversing stroke or to the therety changed position of the fiber sliver relative to the small belt 6, Transversal holes 63 and compression holes 61 are placed in regular ahemation.
With the small belt 60 in Fig. 3. a transversal hole is alw^s placed between two compression

holes. For air consurrytion it is however more advantageous if the number of transversal holes 63 is smaller than the number of compression holes 61. For instance in Fig. 4, with the smaJJ belt 600, one transversal hole 63 follows every two compression holes 61. In this manner, good compression is achieved with less air consumption and traversing of the liber sliver.
Comprehensive tests have shown that the gathering together of the fiber sliver by the suction air stream, transversally to the conveying direction, begins immediate^ upon emergence from the pair of output rollers, but ends after a short distance. This gathering together is independent of the staple length. Suitable design of the perforation as described above is furthermore favorable for the gathering together. It has been shown that the suction zone defined by the groove 41 need not to extend as far as the delivery cylinder 5. Shortening the suction zone fiirthermore increases the effect of the suction air stream in the shortened area and thereby increases the gathering together of the fiber sliver. Shortening the suction zone even allows for considerable reduction of the suction capacity Wiile the bundling eSect remains the same.
Fig. 6 shows an embodiment in which the groove 41 in the belt cage 4 extends only over less than one half of the length of the belt cage 4. The groove 41 \^4iich is connected to the suction channel 42 is located in the portion of the belt cage 4 which is away from the deliveiy cylinder 5 and is open towards the output cylinder of the drafting equipment. The length of this suction zone is approximately 10 to 25 mm. In this short zone the fiber sliver is already gathered together completely. The suction zone can therefore be kept as short as possible to save suction air capacity, i.e. it is orify as long as is absolutely necessary for the gathering together of the iibers With long fiber staples the width of the cylinder nip is greater in fiinction of the staple length. In that case too, the suction zone may not be greater. Following the suction zone, the grooves 62 in the small belt 6 then possibly assume the cohesion or the clamping of the fibers gathered together, as described earlier.
In addition, subsequent conpression may also take place between the suction zone defined by groove 431 and the nip of the delivery cylinder 5. For this purpose a channel 43 is provided which connects the groove 41 to the subsequent compression are before the delivery cylinder 5.
Figs. 11 and 12 show an alternative embodiment of the compression device, in which two perforations 61 and 61' as well as 63 and 63' are provided. At the perforation 61', 63', the perforation openings are additionally connected to the grooves 62, The variants according to Figs 3 and 4 are combined here, but due to the asymmetrical placement of the groove 410 in the belt cage 40, always only one of the perforation rows is operating at a time. The groove 410 is connected via a suction channel 420 to the exhaust suction which is not showa
This embodiment has the advantage that the compression device can easily be adapted to different roving thicknesses and material requirements by turning over the small beh 660. The small belt

660 is thereby more flexible in its application than a belt with only one row of pedbratioas.
D£ 43 23 472 describes that as a result of the suction air stream it happens that fiber ends are sucked through the perforation and are then caught between the small belt 6 and the upper roller S. This leads to annoying interference during spinning because these fibers are unable to follow the direction of the fiber sliver being twisted into a yam. It is therefore desirable to lift the belt6 from the delivery cylinder 6 in the output area in order to prevent this clamping of the fibers In the above-mentioned DE 43 23 472 this lifting of the belt 6 is effected through suitable selection of the belt material. A lifting eflfect can however be also achieved by providing a groove mt he delivery cylinder 5 under the perforation, so that the belt 6 does not lie on the delivery cylinder 5 at that location. These measures require however special design of the delivery cylinder 5 or also of the belt 6. Furthermore the belt 6 is less resistant to wear if it lacks a fabric layer.
According to the present invention, a free space is created in the run-out of the delivery cylinder 5 by providing a ridge 2 Over \Adch the belt 6 is guided immediately following the nip of the delivery cylinder 5. The ridge 2 is attached to a holder 21, The ridge 2 is adjustable by adjusting this holder 21. Tlus ridge 2 not only serves to create clearance to prevent the catching of the fibem, but thatiki to the more pronoxmeed deflection of the belt 6, the fibers are more easily detached frf m the belt 6, especially v^en fine yams are spua Peeling of the fibers is avoided in any case, thus resulting in better and more unifonm yam quality.
If the suction is operating for a long period of time in the fiber bundling zone, an accumulniion of fiber fly and dust in the groove 41 cannot be avoided, so that the operation of the pneumatic conqjression device is gradually affected. The traveling blowers nomially used with ring spinning machines cannot be used for satisfactory cleaning in this case because they are only externally effective. Disassembly for cleaning of the pneumatic compression device is however very expensive.
Figs 9 andlO show an embodiment in which a cleaning device for the conpression device is provided. A blowing air diannel 45 with a connection piece 44 lets out in the belt cage 4 info the groove 41 across from the outlet of the suction air channel 42. If cleaning is to be carried out, compressed air is introduced through this blowing air channel 45, while the negative pressure through the suction air channel 42 is however maintained. It has been shown that the dirt which settles generally in the groove 41 and especially at the outlet of the suction channel 42 can be successfiilfy removed in this manner. The compressed air is conveyed to the connection piece 44. This can be done manuaUy but also by means of an automatic traveling carriage.
In the arrangement of Fig. 10 two con^ression devices are attached in a pair to a carrier which in turn is held in the conventional bearing ami of the drafting equipment on which the upper roller pair of the delivery cylinder 5 is also mounted in the center. To avoid the necessity for the service

carriage to recognize in each instance whether the spinning station involved is on the right or on the left side of the bearing ann of the^draflmg equipment, the connection pieces 44 and 44* are given identical positions relative to the spinning station. Cleaning advantageously takes place m conjunction with yam breakage repair. When the service carriage is positioned at a spinning station, the identical placement of the connection piece 44 or 44' relative to the spindle ensures that the service carriage ensures that it is able to service the connection piece 44 or 44' without making a distinction. The cleaning device thus not only carries out successful cleaning of the compression device but furthermore can be easily operated by a service carnage.
Reduction of the suction e£^t can occur as a result of dust settling in the perforation. AJso burrs at the edge of the perforation can cause fibers to get caught on them
It has been shown that a debarred perforation operates without problems and without clogging even when the material is very dirty. Such a burr-free perforation is obtained by breaking the edges which have normally bum as a result of the usual punching process.
It is more economical and sin^ler in production to make the perforation by means of a laser ray. With this production process clean and burr-free perforations are produced, and these surprisingly have no tendency to be clogged by dust or catching fibers.

REFERENCE LIST
2 Ridge
21 Ridge holder
3 Carrier
4,40 Belt cage
5 Delivery roller
41,410 Groove
42,42', 420 Suction channel
43 Channel
44,44* Connection piece
45 Blown-air channel
6, 60,600, 660 Small belt
61, 61* Compression holes, perforation openings
62 Groove *
• 63, 63' Transversal holes, perforation openings

1. A double-apron drafting system for spinning machinery, comprising a fibre bunching zone which joins the pair of front rollers of the main drafting zone and is followed by a delivery device (5) wherein a pneumatic condenser device is arranged between the pair of front rollers and the delivery device (5) that has a perforated apron (6) and a suction device which is configured as a apron cage (4) and extends on the apron side facing away from the fibre structure (FS) and draws in air through the fibre structure, characterized in that a^blow air line (45) has its mouth opposite the mouth of the suction air line (42, 42*) in the apron cage (4) formed as a housing.
2. The device according to claim 1, characterized in that a connecting sleeve (44, 44*) is provided at each spinning position to feed blow air thereto.
3. The device according to according to one of claim 1 or 2, characterized in that the connecting sleeve (44, 44') is arranged at each spinning position in the same way each with respect to the spinning position.
4. A method for cleaning the air-flow paths of a pneumatic condenser device which is arranged in the fibre bunching zone of a double-apron drafting system for spinning machinery following the pair of front rollers of the main drafting zone and has a suction device which draws in air through the completely drawn fibre structure (FB) that requires condensing, characterized in that compressed air for cleaning is led into the suction device (4) with the negative pressure, however, being maintained at the same time.

5. A double-apron drafting system for spinning machinery substantially as herein described with reference to the accompanying drawings.
6.A method for cleaning the air-flow paths of a pneumatic condenser device which is arranged in the fibre bunching zone of a double-apron drafting system substantially as herein described with reference to the accompanying drawings.

Documents:

942-che-2003-abstract.pdf

942-che-2003-claims duplicate.pdf

942-che-2003-claims original.pdf

942-che-2003-correspondence others.pdf

942-che-2003-correspondence po.pdf

942-che-2003-description complete duplicate.pdf

942-che-2003-description complete original.pdf

942-che-2003-drawings.pdf

942-che-2003-form 1.pdf

942-che-2003-form 19.pdf

942-che-2003-form 26.pdf

942-che-2003-form 3.pdf

942-che-2003-form 5.pdf

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Patent Number

202956

Indian Patent Application Number

942/CHE/2003

PG Journal Number

05/2007

Publication Date

02-Feb-2007

Grant Date

01-Nov-2006

Date of Filing

17-Nov-2003

Name of Patentee

DEUTSCHE INSTITUTE FUR TEXTIL-UND FASERFORSCHUNG STUTTGART

Applicant Address

KORSCHTALSTRASSE 26, D-73770 DENKENDORF, GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	PETER ARTZT	HUGO WOLF-STRASSE 16, D-72766 REUTLINGEN, GERMANY
2	HOLGER ZOUDLIK	TUBINGER STRASSE 70, D-70178 STUTTGART, GERMANY

PCT International Classification Number

D01H5/86

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	19709580.1	1997-03-08	Germany
2	19719773.6	1997-05-10	Germany
3	19722528.4	1997-05-30	Germany