System for compacting fibers

Abstract

The present invention relates to a system (1) for compacting fibers to be used at two adjacent spinning positions of a ring spinning machine, wherein the system comprises a body (2), which comprises a suction duct (2.1) that is connectable to a suction tube of the ring spinning machine; and at least one suction drum (3) being assigned to one spinning position and being rotatably connectable to the body along an axis of rotation (A) and thereby building a gap (4) running around the axis of rotation (A) between the body (2) and the respective suction drum (3); and wherein the system (1) comprises for at least one of the two suction drums (3) a protection band (5) that is designed to envelop at least the gap (4) when in operation position. The invention further relates to a protection band (5) to be used in such system (1) as well as a ring spinning machine comprising such system (1).

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention disclosed refers to a system for compacting fibers in a ring spinning process.TECHNOLOGICAL BACKGROUND

[0002] Compacting devices to be used at two adjacent spinning units of a ring spinning machine are known. Such compacting devices are for instance disclosed in EP 2 828 423 A1 and comprise a carrier element to which a suction drum is connectable. The carrier is detachably connected to the ring spinning machines suction air supply. The suction drum being associated with the output roller pair of the stretching unit in question, and the suction drums being rotatably mounted on a shaft which is secured to the carrier element. The suction drum is perforated with the purpose of compacting the fibers running along these perforations.

[0003] In use it shows that the perforations are quickly chocked by the fibers entering the perforation during being subjected to suction air / negative pressure. Further fiber debris, dust or the like enter the suction drum not only through the perforations but from different sides through openings and gaps. If a compacting device is clogged, chocked and / or soiled with fiber, dust and / or fiber debris an operator at the spinning mill needs to remove the compacting device from the respective spinning units to detach the suction drum for cleaning the perforations as well as the interior space (incl. bearing or shaft). This is to say that removal of fiber debris is cumbersome and labor-intensive. A clogged, chocked and / or soiled compacting device results in a decrease of compacting quality.

[0004] The aim of the present invention is to minimize or eliminate these disadvantages of compacting devices.DESCRIPTION OF THE INVENTION

[0005] The object of the present invention is to provide an improved system for compacting fibers at two adjacent spinning positions of a ring spinning machine in order to overcome the disadvantages, especially the clogging and chucking of the suction drum, as referred to in the above and thereby increasing the quality of the resulting compact yarn and the efficiency of the spinning mill.

[0006] The essence of the invention lies in a system for compacting fibers according to independent claim 1. The system for compacting fibers is to be used at two adjacent spinning positions of a ring spinning machine and comprises a body, which comprises a suction duct that is connectable to a suction tube of the ring spinning machine. Further the system comprises at least one suction drum, which is assigned to one spinning position and being rotatably connectable to the body along an axis of rotation. When connected to the body a gap running around the axis of rotation is built between the body and the respective suction drum is build. The system further comprises for at least one of the two suction drums a protection band that is designed to envelop at least the gap when in operation position.

[0007] The body of the device comprises a suction duct that is connectable to a suction tube (i. e. negative pressure source / suction air supply of the ring spinning machine) of the ring spinning machine. The suction tube runs along the side of the ring spinning machine and is therefore part of several spinning units. In case of the ring spinning machine comprising an intermediate drive the suction tube may be of two parts reaching from the intermediate drive towards the foot stock and from the intermediate drive towards the head stock. The suction duct is arranged in such way, that the suction drum when rotatably attached to the body is subjected to suction air.

[0008] Each suction drum is rotatably connectable to the body along an axis of rotation. A radial bearing may be situated in the body or in the suction drum. The suction drums are detachably connected to the body so the operator can remove the suction drum for removing the fiber debris (dust, fibers, fiber debris etc.) from perforations and / or the inside / inner surface of the suction drum. A non-detachable connection is however not excluded from the invention. In such case the whole system needs to be detached from the spinning unit in order for it to be removed from dust, fibers and / or fiber debris.

[0009] When the suction drum / suction drums are connected to the body a gap running around the axis of rotation between the body and the respective suction drum is built. The gap has an axial extension. However, due to the bearing play of the radial bearing (due to the one-sided radial load exercised when in operation mode / operation position) the gap is not necessarily coaxial with the axis of rotation, meaning it is non-circular during the process of compacting, i. g. in operation position / operation mode - at least not for the entire time.

[0010] The protection band is a means for protecting in a permeable-to-air way at least the gap built between the body of the system and the suction drum(s) from dust, fibers and / or fiber debris to enter the suction drum, the inside of the suction drum. The protection band is designed and attached in a way that allows for compensation of bearing play that alters the form of the gap in its radial orientation. The protection band may be tube-like with a wide that provides for the coverage (axially seen) of at least the gap. It may also cover the compacting perforations. The tube-like embodiment of the protection band is advantageous because it can be produced as a tubular fabric / as a tubular good, which is economically advantageous. Also, it is adaptable in wide. E. g. if a shorter suction drum is used and the gap is axially larger the wide of the protection band may be adapted respectively by cutting off a larger piece of the tubular fabric.

[0011] In tests it was shown that around 40% of the clogging of the suction drum caused by fiber debris happens by the fiber debris entering the inside the suction drum through the gap built between the body and the suction drum. The protection band enveloping the gap helps to keep the fiber debris, fibers and / or dust from entering the inside of the suction drum and is instead accumulated on the proception band. The protection band may be loosely placed over the gap - it must envelop the gap perpendicular to the axis of rotation (= basically along the way the suction air takes).

[0012] Test have further shown that after 5 hours in use the system for compacting fibers according to the invention shows up to 90% less fiber accumulation inside the suction drum and the body compared to currently available systems. Meanwhile, the quality of the produced compact yarn was maintained.

[0013] The term operation position in the context of the invention refers to the situation, when the at least on suction drum is attached to the body of the system and a gap as described above is built. If the system is connected to the ring spinning machine it is too in operation position. When talking about operation mode it is intended to refer to a system in operation position and carrying out the compacting process, i. e. the protection band is attached to the suction drum. A system in operation mode is also in operation position.

[0014] Advantageously the suction drum further comprises a plurality of compacting perforations and the protection band covers said compacting perforations of the suction drum.

[0015] The compacting perforations serve the suction air to act on the fibers passing the rotating suction drum when in operation position and in operation mode. The compacting perforation, in most cases holes, have a diameter in the ratio wall thickness of the suction drum to perforation diameter < 1. This ratio results in an optimal suction effect on the fibers to be compacted. The compacting perforations, possibly arranged in a single row or in multiple rows, could also be designed as slots, or as a slotted groove.

[0016] The compacting perforations are covered by the protection band. The protection band, covering at least the gap, covers in addition the compacting perforations. It covers the compacting perforations in the suction drum in such a way that there is still sufficient negative pressure / suction air and thus volume flow to compact the fibers of the yarn to be produced. However, the fibers to be compacted are no longer drawn into the compacting perforations causing the system to chock.

[0017] The suction drum may be covered by at least one protection band. For example one protection band may cover the gap and on my cover the compacting perforations.

[0018] Only the perforations that have the purpose of compacting the yarn are covered by the protection band. This is to say that additional perforations / slots / bores that serve a different purpose (e.g. flushing air bore) are not being covered by the protection band.

[0019] The protection band does not only protect the suction drum and the body from being entered / clogged / chucked by fibers / fiber debris and / or dust but also the fibers to be compacted. The protection band enables the fibers to be compacted to smoothly pass the compaction perforations and thereby increasing the quality of the compacted yarn produced. Further the protection band allows for more flexibility in the design of the perforations in the suction drum. Since the fibers to be compacted are not in direct contact with the compacting perforations on the suction drum a more cost-effective way of production of the suction drum may be chosen (e. g. less but larger perforations, not as high quality of production necessary).

[0020] Advantageously the protection band is removably attached to the suction drum.

[0021] The protection band may be pulled or inverted over the suction drum respectively over a region of the suction drum in way that allows for enveloping the gap, namely pulling or inverting not the entire extend of the protection band (i. e. its wide) over the suction drum. The mentioned region may include After use or when worn out or defect the protection band can be pulled of and be replaced by a new protection band.

[0022] In embodiments the protection band may be glued to the suction drum / over the gap or over the gap and the suction drum in the region of the compacting perforations - this connection too, may be reversable e. g. by the application of heat and / or solvents. It is also conceivable that the protection band comprises two parts, e. g. one protection band is e. g. glued over the compacting perforations and one is pulled over a part of the suction drum in a way that allows for enveloping the gap.

[0023] Since the protection band due to its composition / texture is worn out earlier than the suction drum it is advantageous if it is replaceable easily and at low costs.

[0024] In advantageous embodiments the protection band is made of fabric, metal, plastics or a composition thereof.

[0025] In case the protection band is made of a fabric it may be woven or knitted. The fabric may be a textile, metal or plastic fabric. Composition of textile and metal or plastic or metal or metal and plastic are conceivable. The so generated mesh is of size that does not allow fibers, fiber debris and / or dust to pass through. The size of the mesh is of between 50 - 300 µm, of between 80 - 200 µm, of 100 µm, of 50-60 µm, of 110 - 200 µm.

[0026] In case the protection band is made of a metal it may also be woven or knitted or it may be designed as a foil with perforation and or a thin metal ring with perforations. The term very thin is used to express, that the metal ring may be easily deformed - it is stiffer than a foil but still deformable to e. g. adapt to the changes is the circumference of the suction drum over its axial extension. The thin metal ring may be deformed in the region of the gap in order to fulfil the function of the protection band including the adaptation in case of altered radial form of the gap due to bearing play. In cases it may however be sufficient to only axially cover the gap - in such cases the perforated metal ring does not have to be deformable in a way that allows for adaptation in case of altered radial form of the gap due to bearing play.

[0027] This is advantageous especially if the protection band is placed over the compacting perforations in the suction drum and the gap between the suction drum and the body and the suction air needs to be flowable through the protection band in order to act on the yarn passing the perforations in a compacting way. It is not excluded from the invention that in a region the air-permeability is limited, i.e. the mesh size is smaller than the above mentioned 50 - 300 µm or, alternatively, there is no mesh / pores / perforations in place. The degree of air-permeability is defined by the mesh size, size of perforations and in general the material used.

[0028] Advantageously the protection band is of a flexible structure. This is advantageous in two ways: firstly, a flexible protection band that is e. g. tube-like, made of a tubular good, and due to its flexible structure is pullable over the suction drum. Depending on the design of the suction drum (stepped, not stepped) the protection band is rotatably stable attached to a region of the circumference of the suction drum that allows the protection band to envelop the gap or the gap and the at least one compacting perforation. For instance, a stretching of up to 20% of the initial size of the protection band (e. g. diameter) is possible, e. g. stretching of 5 - 10 % is possible. The stretching is dependent on the material of the protection band, e.g. elastomeric material or composite thereof or material of a certain tensile strength that allows to stretch the material (e. g. very thin metal sheet or foil)

[0029] Secondly, in the case of a protection band of a flexible structure can take up changes in the diameter of the gap, which is enveloped by, covered by, the protection band. As mentioned, the protection band is rotatably stable attached to the suction drum at at least the points of the same diameter (gluing) or a larger diameter than the diameter of the protection band and is rotatable at points of smaller diameters, especially in the region of the gap between the suction drum and the body and in cases in the region of the protection ring. Smaller relative movements between the protection band and the suction drum is possible due to the force applied by e. g. the nip rollers (see below).

[0030] The system advantageously further comprises a protection ring to be arranged between the suction drum and the body.

[0031] The protection ring may be a separate part or may be an integral part of the body. The protection ring reduces the size of the gap and contribute to the protection of the inside of the suction drum to be entered by fibers / fiber debris and / or dust.

[0032] In case of the presence of a protection ring the protection band may be of a different wide since the gap is smaller. In an embodiment the protection band may, in axial view, also cover the protection ring. The protection ring may have the function of attaching the protection band thereto in form of an integral joint or a form fit connection.

[0033] Advantageously the system further comprises a suction attachment connectable to the suction duct of the body.

[0034] This suction attachment is connectable to the suction duct of the body and is of a dimension and of a position that allows for removal of the fibers, fiber debris and or the dust accumulated on the protection band in the area of the gap and / or the compacting perforations of the suction drum in operation position and in operation mode. An arrangement of the suction attachment as described allows for optimal volume flow of air to compact the fibers of the yarn to be produced and helps to prevent the mesh / pores or perforations of the protection band to be clogged by fibers, dust and / or fiber debris.

[0035] The connection between the suction duct of the body and the suction attachment is preferably reversable and airtightly

[0036] The system further comprises at least one transmission wheel that is connectable to the at least one the suction drum and is designed to be brought into contact with a driven element of the spinning position of the ring spinning machine.

[0037] In an advantageous embodiment the suction drum is driven by the transmission wheel when in operation mode, i.e. when the transmission wheel is in contact with the driven element of the spinning unit of the ring spinning machine and the ring spinning machine is working. The transmission wheel may be an integral part of the suction drum that is brought - when in operation position and operation mode - into contact, i. e. driving connection, with a driven element of the spinning position of the ring spinning machine, e. g. the lower exit roller shaft of the drawing frame that runs along the whole side or part thereof of the ring spinning machine and is part of each spinning unit at this side of the ring spinning machine. The transmission wheel may be a separate part of the system being attached to the suction drum and is brought, in operation position, in contact with a driven element as described above. The transmission wheel has the function of transmitting the rotation movement of the driven element of the spinning unit of the ring spinning machine to the suction drum, which is rotatably connected to the body.

[0038] For certain types of protection bands (which in themselves may be dependent on the fiber material to be spun in terms of the choice of material and / or the degree of air permeability), it can be advantageous if the suction drum has at least one peripherally arranged mounting aid for the protection band on one end face. Such a mounting aid can be, for example, a chamfer or a rounding. According to one variation of the invention, the suction drum and / or the body may also have a positioning aid that facilitates the positioning of an assembly tool used to apply new protection bands and / or remove used protection bands to the suction drum. A positioning aid may, for example, be a recess and / or a protrusion.

[0039] The system further comprises at least one nip roller arranged to be brought into contact with the perforations of the at least one suction drum.

[0040] The nip roller is arranged on at least one or on both sides of the body, each assigned to a spinning position and at least one providing a suction drum, normally both providing a suction drum. The nip roller(s) is designed to be brought into contact with the respective suction drum, more precisely with the at least one (compacting) perforation with compacting purpose that may be covered - or not - with the protection band. In cases this at least one compacting perforation is arranged along the circumference of the respective suction drum. In operation position / operation mode the fibers of the yarn to be produced run between the compacting perforations covered - or not - with the protection band and the nip roller.

[0041] The arrangement may include a releasable folding / snap mechanism - the nip roller stays in contact with the suction drum respectively the protection band as described and is releasable only via force application.

[0042] In a further advantageous embodiment of a system 1 the system 1 further comprises a clip arranged at the lateral end of the suction drum. The lateral end of the suction drum being the end opposite the end of the suction drum designed to be attached to the body of the system. The clip helps to prevent the fibers / dust and / or fiber debris or even the yarn to be produced from entering the system through the opening at the lateral end of the suction drum. In case of a yarn breakage the broken end of the yarn may be drawn into the opening of the lateral end of the suction drum and be wound up e. g. a shaft portion inside the suction drum.

[0043] In an advantageous embodiment the suction drum comprises at least one non-compacting bore in a region that is not covered by the protection band. The non-compacting bore is a bore / perforation / slot that has a purpose that is different from compacting fibers. E. g. the non-compacting bore may be a flushing air bore. The flushing air bore is of a very small diameter: e. g. 0.3 mm compared to 1.5 mm diameter of an exemplary compacting perforation. The flushing air bore must not be covered by the protection band. The purpose of such non-compacting bores may be different. In the case of a flushing air bore some air flow is generated that helps to remove still accumulated dust, fibers and / or fiber debris in the inside of the suction drum.

[0044] The concept of a suction drum with at least one non-compacting bore and with at least one compacting perforation can be considered as an independent inventive concept. This concept can therefore be used independently of the described suction drum with at least one compacting perforation. It may also be used independently of the described suction drum with at least one compacting perforation but without at least one protection band.

[0045] The essence of the invention is further a protection band to be used in a system as described above and wherein the protection band is at least partially of a flexible material. It may further be made of fabric, metal, plastics or a composition thereof and is permeable to air.

[0046] The protection band is permeable to air and is made of a woven or knitted fabric, metal, plastics or a composition thereof. The flexibility of the protection band refers especially to its radial flexibility / deformability, given, that the protection band is made of a tubular good and cut of resulting in a wide of the protection band that covers at least the gap in its axial extension. In an embodiment the protection band not only covers the gap but also the region of the circumference of the suction drum provided with at least one compacting perforation. An exemplary wide is 10 - 30 mm or 15 - 25 mm or 20 mm or 15 mm or 22 mm. An exemplary diameter is 25 to 30 mm. Depending on the structure of the mesh, e. g. the distance between the wraps and the wefts, it is advantageous if the wide of the protection band and the diameter of the protection band are in a relation between 1:0.3 to1:1.

[0047] The protection band may be of a kind as described throughout this text with regards to its flexibility (stretching), deformability, structure (e. g. mesh structure, size, perforated foil, thin and deformable metal ring), air-permeability, material composition and the like.

[0048] The essence of the invention is a ring spinning machine comprising at least a spinning unit comprising a system according to the invention and at least comprising a body, which comprises a suction duct that is connectable to a suction tube of the ring spinning machine and at least one suction drum being assigned to one spinning position and being rotatably connectable to the body along an axis of rotation and thereby building a gap running around the axis of rotation between the body and the respective suction drum; and wherein the system comprises for at least one of the two suction drums a protection band that is designed to envelop at least the gap when in operation position. The system may be of a kind as described throughout the text and may comprises further elements such as transmission wheel, non-compacting bore, clip, a protection band as described herein of certain material, structure etc..SHORT DISCRIPTION OF THE DRAWINGS

[0049] Further advantages of the invention are described in the following embodiments. They show, in each case schematically: Figure 1an oblique frontal view of an embodiment of the system Figure 2the system as shown in Figure 1 with detached protection bands Figure 3an embodiment of a body of the system Figure 3an embodiment of a suction drum Figure 5a detail of an embodiment of a suction drum Figure 6an embodiment of a suction attachment WAYS OF CARRYING OUT THE INVENTION

[0050] Fig. 1 shows an embodiment of a system for compacting fibers 1 to be used at two adjacent spinning positions of a ring spinning machine in operation mode. The system 1 comprises a body 2 to which at least one, here two, suction drums 3 are rotatably and preferably detachably connected along a rotation axis A. The bearings, shafts etc. of the connection or of the detachable connection of the suction drums 3 to the body 2 are not shown since publicly know from e. g. WO 2015 / 128713 A1. The connection between the body 2 and the respective suction drum 3 is not airtight and therefore allowing air and dust, fibers and / or fibers debris to enter the system 1, especially the inside of the suction drum 3 and both, the additional air as well as the dust, fibers and / or fibers debris contribute to a decrease of the compacting quality, i. e. less negative pressure acts on the yarn to be produced. Between the body 2 and the suction drum 3 a gap 4 is built when they are connected to each other. In the depicted embodiment this gap 4 is partially covered by an optional protection ring 6. This arrangement helps to seal the gap 4 so the air flow is not altered which can reduce any negative effects on the compaction quality. However, this kind of sealing is not airtight and leaves the possibility for dust, fibers and / or fiber debris to enter the system 1. This is to say that a protection ring 6 does not fulfil the function of the protection band 5 in this embodiment, the latter being necessary still to prevent dust, fibers and / or fiber debris from entering the system 1.

[0051] The body 2 comprises a suction duct 2.1 that is connectable to a suction tube of the ring spinning machine. The suction air / negative pressure is delivered through the suction duct 2.1 to the suction drum 3. The suction drums 3 show each at least one compacting perforation 3.1 of a certain diameter (e. g. 1.5 mm) running along the circumference of the suction drum 3. The fibers of the yarn to be produced will, in operation mode pass these compacting perforations 3.1 and be subject to the suction air / negative pressure. To avoid the fibers and / or fiber debris and / or dust to pass through the compacting perforations 3.1 a protection band 5 is positioned over the compacting perforations 3.1.

[0052] The protection band 5 is firmly pulled over the region of the circumference of the suction drum 3 with the compacting perforations. For example the protection band 5 may be a tubular good made of a flexible / deformable material and may e.g. be 10 - 30%, or 20% smaller in diameter than the suction drum 3 in the region of the compacting perforations 31 in order to be tightly fitted on the suction drum 3. An example is a suction drum 3 of 34 - 35 mm in diameter and a protection band 5 of 27 to 28 mm in diameter.

[0053] By pulling a smaller in diameter protection band 5 over the suction drum 3 the protection band 5 is more or less rotationally stable, meaning that only minor rotational movements are possible, e. g. exercised by the nip roller 9. It is also possible that the protection band 5 is of the same diameter (the protection band 5 being a tubular good) as the diameter of the suction drum in the region, where the protection band 5 is attached to. In such cases the protection band 5 may be glued or mechanically attached to the suction drum 3.

[0054] The protection band does not have to be made of a tubular good but may be a piece / ribbon of a woven or knitted fabric, metal, plastics or a composition thereof and brought into a shape enveloping the at least gap, and eventually the compacting perforations too, in situ by the use of Velcro, glue or by sewing or otherwise mechanically attach the ends of the piece / ribbon.

[0055] The part of the protection band 5 covering the gap 4 is due to its design, material composition, and / or the way of attachment to the suction drum larger in diameter than the parts building the gap 4 in the region of the gap 4. This allows for rotational movement of the protection band 5 in alignment with the rotational movement of the suction drum 3 and therefore the possibility to adapt to an altering diameter of the gap 4 caused by the compensation of the eventually occurring bearing game.

[0056] The suction attachments 7 in Fig. 1 are arranged to remove the accumulated dust, fiber and / or fiber dust from the protection band 5 in at least the region of the compacting perforations 3.1 in the suction drum 3. To improve the prevention of dust, fiber and / or fiber dust from entering the system 1 it is possible to arrange and design the suction attachments 7 in a way that allows for removal of dust, fiber and / or fiber dust from the protection band 5 in the region of the gap 4 too.

[0057] Fig. 1 further shows a nip roller 9 acting on the suction drum 3 in the region of the compacting perforations 3.1, respectively acting on the protection band 5 covering the at least one compacting perforation 3.1.

[0058] The suction drum 3 provides for a flange portion 3.2, where a transmission wheel (not shown) for transmitting a rotational movement from a driven element of the spinning unit of the ring spinning machine to the rotatable suction drum 3 may be placed.

[0059] Fig. 2 shows the system 1 as depicted in Fig. 1 but with the at least one, here two, protection band 5 detached from the suction drums 3. The form of the protection band 5 is in this view adapted to the diameter of the suction drum (meaning the diameter of the suction drum 3 in the region of the compacting perforations 3.1) and the gap 4 respectively the protection ring 6. It is to be noted that in Fig. 2 the protection band 5 is shown in its form as if it is attached to the suction drum 3. Should, in praxis, the protection band 5 be removed from the suction drum 3 its form due to its flexibility / deformability looks slightly different. As described already the protection band 5 may be made of fabric, metal, plastics or a composition thereof. Further the protection band 5 is flexible or at least deformable. The flexibility may result from the material and / or the structure of the protection band 5. The protection band 5 may be a woven or knitted fabric, metal, plastics or a composition thereof. It may also be made of a thin sheet of metal, plastics or a composition thereof in the form of a ring or of a foil. In any case the protection band 5 must be provided with small perforations that prevent fibers, fiber debris and / or dust from entering the gap and / or the compacting perforations 3.1. Depending on the mesh size or the perforation size a certain air-permeability is achieved. This air-permeability may vary over the extension of the protection band 5 in any direction. In embodiments at least one edge area of the support band 5, e. g. when made of a woven or knitted structure made of some plastics, may be hardened by e. g. a thermal process. This reduces the air-permeability and enforces the edges and prevents the mesh from being separated.

[0060] Fig. 3 shows an embodiment of a body 2 of the system 1. The body 2 depicted is made of a plastics, e. g. polymeric material. It may be built by two parts connected to a body 2. The body 2 comprises a suction duct 2.1. The suction duct 2.1 is basically the inner space of the hollow body 2 and has the function of directing suction air to the suction drum / suction drums. In the depicted embodiment an opening 2.1.1 of the suction duct 2.1 is shown. The opening 2.1.1 of the suction duct 2.1 is connectable to the suction tube of the spinning position of the ring spinning machine. This connection is preferably airtight. Next to the opening 2.1.1 of the air duct 2.1 two suction attachments 7 are shown. The suction attachments 7 are connected to the suction duct 2.1. The suction attachments 7 may be separate parts as shown in Fig. 4 or may form an integral part of the body 2. The suction attachment / suction attachments 7 have the function of removing in operation mode the dust, fibers and / or fiber debris accumulated on the protection band(s) in the region of the gap or in the region of the gap and the at least one compacting perforation. The suction duct 2.1 is divided into two directions for providing suction air / negative pressure to the suction drum(s) when in operation mode. For this purpose the body 2 may be provide with at least one suction slots 2.1.2, which, in operation position are covered by the suction drum / suction drums, especially by the at least on compacting perforation. The suction drum, when rotatably connected to the body 2 in the region of e. g. the suction slots 2.1.2, is not airtightly connected. This results in an air flow entering the suction drum through the gap built between the suction drum and the body 2 perpendicular to the rotation axis A. Thereby the compacting efficiency decreases. As shown in Fig. 1 this problem is solved by the system comprising a protection band or a protection band and a protection ring that seal the gap.

[0061] Fig. 4 shows an embodiment of a suction drum 3 of the system 1. The suction drum 3 is made of a plastics, e.g. a thermoplastic, a reinforced plastics or a metallic material. The suction drum 3 is basically of a hollow-cylindrical shape. It comprises a flange portion 3.2 for the attachment of a transmission wheel (not shown) and it further comprises along its circumference at least one compacting perforation 3.1. In the depicted embodiment the compacting perforations 3.1 are arranged in a single row along the entire circumference of the suction drum 3. In this embodiment the compacting perforation 3.1 are of circular shape with a diameter of 1.5 mm - however, diameters in the range of including 0.5 to 3 mm are conceivable, e.g. 1.2 mm or 1.6 mm or 1.4 mm or 1.7 mm. It is also possible that the compacting perforations 3.1 are arranged in two rows or even more rows. Also, the compacting perforations may be of a slotted form or of another geometric cross section.

[0062] In the depicted embodiment the suction drum 3 has a stepped circumference. At least one step 3.4 is designed for taking up the protection band so the protection band, when attached to the suction drum 3, is flush with the circumference of the larger diameter. The diameter of the suction drum 3 is in the range of 25 - 45 mm, in cases between 30 and 40 mm, in cases 33 - 37 mm, in cases 35 mm. A first step 3.4 may be realized at a diameter of 34.6 mm so a protection mesh of 0.2 mm thickness may be pulled over the suction drum 3. The step 3.4 may also act as a stop when pulling over / attaching the protection band to the suction drum 3.

[0063] The suction drum 3 as shown in Fig. 4 further shows a shaft portion 3.3 extending along the rotation axis A of the system. The shaft portion 3.3 serves to connect the suction drum 3 to the body 2 of the system 1. In the shown embodiment the shaft portion is beared in the suction drum 3. In an alternative embodiment it is possible to connect the suction drum 3 to a shaft portion provided by and beared in the body of the system. The connection between the suction drum 3 and the body 2 is rotatable or rotatable and detachable.

[0064] Fig. 5 shows a detail of the suction drum 3 of the system. In this figure the step 3.4 is shown in more detail. Further it is shown that the circumference of the suction drum 3 may comprise perforations / bores that do not have a compacting function. Such perforation / bore may be e. g. a flushing air bores 3.5 that have the purpose of allowing air to enter the system respectively the suction drum in a region of the suction drum 3 not covered by the protection band and help to remove dust, fibers and / or fiber debris still accumulated in the inside of the suction drum 3 to the air flow generated in the region of the compacting perforations 3.1 and thereby exiting the system through the suction duct 3 of the body of the system.

[0065] In this embodiment of a suction drum 3 the shaft portion for connecting the suction drum to the body is arranged on the body and not on the suction drum.

[0066] Fig. 6 shows an embodiment of a suction attachment 7 to be used in a system according to the invention. The suction attachment 7 in this embodiment is a separate part. It is hollow and comprises a lower part 7.1, in this embodiment the lower part 7.1 is threaded, as well as a collar 7.2. Both parts are to be brought into contact with a respective opening in the body of the system in the region of the suction duct. The suction attachment 7 comprises an upper part 7.3, which is oblique and has at its upper end a mouth 7.4. The mouth 7.4 of the suction attachment has the function of applying suction air / negative pressure originating from the ring spinning machine and delivered through the suction tube of the spinning position of the ring spinning machine and through the suction duct of the body of the system and the suction attachment attached to the body respectively the suction duct of the body of the system to a defined area of the suction drum, when in operation position and operation mode (i. e. suction air is delivered). The design of the mouth 7.4, e.g. its extension, its geometric form, its position within the system when attached to the body defines the area of suction air application. In the depicted embodiment the inner diameter of opening of the lower part 7.1 has a diameter of 7 - 9 mm and leads in form of a duct to the mouth 7.4, which has the form of an oblong hole of 3 - 5 mm inner width to 12 - 16 mm inner length. The suction air is lead through the mouth and through a duct-like structure of the lower part to the circular opening. The upper part 7.3 with the mouth 7.4 is oriented such that the mouth 7.4 is - in operation position respectively operation mode - arrangeable on the body in parallel to the rotational axis of the system. The suction attachment 7 is further arranged on the body of the system such that dust, fibers and / or fiber debris accumulated on the protection band on the suction drum in the region of at least the gap. Depending on the embodiment the suction attachment 7 is arranged to provide for suction air / negative pressure not only in the region of the gap but also in the region of the at least one compacting perforation in the suction drum.

Claims

1. System for compacting fibers (1) to be used at two adjacent spinning positions of a ring spinning machine, wherein the system comprises a body (2), which comprises a suction duct (2.1) that is connectable to a suction tube of the ring spinning machine; and at least one suction drum (3) being assigned to one spinning position and being rotatably connectable to the body along an axis of rotation (A) and thereby building a gap (4) running around the axis of rotation (A) between the body (2) and the respective suction drum (3); and wherein the system comprises for at least one of the two suction drums a protection band (5) that is designed to envelop at least the gap when in operation position.

2. System (1) according to any of the preceding claims, wherein the suction drum (3) further comprises a plurality of compacting perforations (3.1) and wherein the protection band (5) covers said compacting perforation (3.1) of the suction drum (3).

3. System (1) according to any of the preceding claims, wherein the protection band (5) is removably attached to the suction drum (3).

4. System (1) according to any of the preceding claims, wherein the protection band (5) is made of fabric, metal, plastics or a composition thereof.

5. System (1) according to any of the preceding claims, wherein the protection band (5) is of a flexible structure.

6. System (1) according to any of the preceding claims, wherein the system further comprises a protection ring (6) to be arranged between the suction drum (3) and the body (2).

7. System (1) according to any of the preceding claims, wherein the system (1) further comprises a suction attachment (7) connectable to the suction duct (2.1) of the body (2).

8. System (1) according to any of the preceding claims, wherein the system (1) further comprises at least one transmission wheel (8) that is connectable to the at least one the suction drum (3) and is designed to be brought into contact with a driven element of the spinning position of the ring spinning machine.

9. System (1) according to any of the preceding claims, wherein the system further comprises at least one nip roller (9) arranged to be brought into contact with the compacting perforations (3.1) of the at least one suction drum (3).

10. System (1) according to any of the preceding claims, wherein the system further comprises a clip arranged at the lateral end of the suction drum.

11. System (1) according to any of the preceding claims, wherein the suction drum (3) comprises at least one non-compacting bore (3.5) in a region that is not covered by the protection band (5).

12. Protection band (5) to be used in a system (1) according to any of the preceding claims, wherein the protection band (5) is at least partially made of a flexible material.

13. Protection band (5) according to claim 12, wherein it is made of fabric, metal, plastics or a composition thereof and is permeable to air.

14. A ring spinning machine comprising at least one spinning unit comprising a system for compacting fibers according to any of the preceding claims.

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