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Apparatus for the sorting or selection of a fibre sliver comprising textile fibres, especially for combing

This application claims priority from German Patent Application No. 10 2006 050 384.8 dated Oct. 20, 2006, German Utility Model Application No. 20 2007 010 686.6 dated Jun. 29, 2007 and German Patent Application No. 10 2007 037 426.9 dated Aug. 8, 2007, the entire disclosures of all of which are incorporated herein by reference.

The invention relates to an apparatus for the sorting or selection of a fibre sliver comprising textile fibres, especially for combing. It is known for fibre slivers to be supplied by means of supply means to a fibre-sorting device, especially a combing device, in which clamping devices are provided which clamp the fibre sliver at a distance from its free end, mechanical means being present which generate a combing action from the clamping site to the free end of the fibre sliver in order to loosen and remove non-clamped constituents, such as, for example, short fibres, neps, dust and the like from the free end.

In practice, combing machines are used to free cotton fibres or woollen fibres of natural impurities contained therein and to parallelise the fibres of the fibre sliver. For that purpose, a previously prepared fibre sliver is clamped between the jaws of the nipper arrangement so that a certain sub-length of the fibres, known as the “fibre tuft”, projects at the front of the jaws. By means of the combing segments of the rotating combing roller, which segments are edged with needle clothing or toothed clothing, the fibre tuft is combed and thus cleaned. The take-off device usually consists of two counter-rotating rollers which grip the combed fibre tuft and carry it onwards.

In order to separate short fibres, neps, dirt and other constituents from a fibre mixture it is known to supply the fibre material in the form of lap rolls to combing machines for mechanical combing-out, the end of the lap web being clamped by a nipper and the end projecting beyond the clamping line being mechanically combed-out by means of the comb clothing of a circular comb. The combed-out fibre tuft is then transferred to a detaching roller pair where it is in turn formed into a coherent web, or “pieced”. When the fibre tuft is removed from the nipper by the detaching rollers, the end severed from the lap is likewise pulled through a mechanical top comb, so that as far as possible no short fibres, neps, dirt and other undesirable constituents remain in the combed web. A disadvantage of that known combing method is, in particular, the discontinuous mode of operation, in which large masses have to be accelerated and decelerated during the operating cycle.

The back and forth swinging movement of the nipper assembly gives rise to very substantial vibration, especially in the case of high nip rates, which on the one hand requires the drive elements and bearing elements to be of suitably stable construction and on the other hand places high demands on the framework of the machine as well as on the base on which the machine is mounted.

In order to be able to remove the partially cleaned fibres from the jaws of the nipper unit using the rollers of the take-off device, either the relatively heavy take-off device needs to move linearly or over part of an arc of a circle to the fibre tuft held between the jaws of the nipper arrangement or, the other way round, the nipper arrangement has to be moved towards the stationary take-off rollers. In the case of the 450 nips per minute usually required, the large masses being moved result in a high level of dynamic agitation of the entire combing machine which limits its operating speed and productivity.

Furthermore, a problem of conventional combing machines is that when the combed fibres are removed by the counter-rotating take-off rollers, up to 50% of the fibre length has not been cleaned by the circular comb, because during the combing process, that is to say when the combing segment passes, the fibres were clamped between the jaws of the nipper arrangement or were located behind the jaws, seen in the transport direction. In order also to clean that portion of the fibres as well as possible, those fibres are conventionally pulled through a top comb arranged in front of the take-off rollers. The top comb is an additional structural element for every combing head.

The detaching roller pair, consisting of a lower detaching roller and an upper detaching roller, is directly adjacent to the nipper apparatus and the circular comb. The lower detaching roller is located between the path of movement of the comb tips of the circular comb and the upper detaching roller and, together with the upper detaching roller, forms the clamping nip for the combed sliver. The nipper arrangement is mounted so as to swing in two directions. Firstly, it is moved, at a distance from the detaching roller pair, towards the path of movement of the comb tips of the circular comb. In that position, the combing of the fibre tuft is carried out by the circular comb. When that operation is complete, the nipper apparatus is raised as a unit so that the fibre tuft that has just been combed arrives in front of the clamping nip of the detaching roller pair. During that movement, the nipper apparatus also approaches the detaching roller nip horizontally. The portion of combed sliver conveyed back at that time point is overlapped with the tips of the new, combed fibre tuft, compressed in the clamping nip of the detaching rollers and drawn in the take-off direction by the detaching rollers, the top comb being inserted into the end of the fibre tuft that has just been combed and combing out that free piece of fibre. As a result of the receding movement of the nipper apparatus and the take-off movement of the detaching roller pair, the combed fibre tuft is detached and a fresh fibre tuft is supplied to the nipper apparatus by the feed roller, clamped and brought into the combing position relative to the circular comb. Such an arrangement is disadvantageous because, in particular, the nipper apparatus has to perform a variety of very large movements with greater or lesser degrees of acceleration. The operating speed is thus considerably limited, a large amount of noise is generated and the inertial forces that arise result in above-average wear. Adjustment of the detaching distance and the feed quantity can be effected only while the machine is stationary. A further crucial disadvantage is that the free end of the fibre tuft that has just been combed also has to be moved at relatively high speed, with its free fibre tips to the front, over large distances and placed in an exactly defined position onto the returned end of the combed sliver. In dependence upon the air vortices that occur and the respective air resistance, the fibre tuft is frequently incorrectly positioned on the returned combed sliver so that it is necessary to operate at relatively low speeds. In any case, however, losses of quality are observed in the combed sliver. A further disadvantage of the known apparatus is that uncontrolled fold-formation occurs between the detaching roller pair and the take-off rollers as a result of the pilgrim-step motion of the detaching rollers, which additionally results in disruption of the combing process.

When the nipper is located in its forward position, it is opened and transfers the combed-out fibre tuft to the detaching roller pair, that tuft being pieced with the previously detached fibre tuft.

The known cotton-combing process is a discontinuous process. During a nipping operation, all assemblies and their drive means and gears are accelerated, decelerated and in some cases reversed again. High nip rates result in high acceleration. Particularly as a result of the kinematics of the nippers, the gear for the nipper movement and the gear for the pilgrim-step movement of the detaching rollers, high acceleration forces come into effect. The forces and stresses that arise increase as the nip rates increase. The known flat combing machine has reached a performance limit with its nip rates, which prevents productivity from being increased. Furthermore, the discontinuous mode of operation causes vibration in the entire machine which generates dynamic alternating stresses.

EP 1 586 682 A discloses a combing machine in which, for example, eight combing heads operate simultaneously one next to the other. The drive of those combing heads is effected by means of a lateral drive means arranged next to the combing heads having a gear unit which is in driving connection by way of longitudinal shafts with the individual elements of the combing heads. The fibre slivers formed at the individual combing heads are transferred, one next to the other on a conveyor table, to a subsequent drafting system in which they are drafted and then combined to form a common combing machine sliver. The fibre sliver produced in the drafting system is then deposited in a can by means of a funnel wheel (coiler plate). The plurality of combing heads of the combing machine each have a feed device, a pivotally mounted, fixed-position nipper assembly, a rotatably mounted circular comb having a comb segment for combing out the fibre tuft supplied by the nipper assembly, a top comb and a fixed-position detaching device for detaching the combed-out fibre tuft from the nipper assembly. Disadvantages of that combing machine are especially the large amount of equipment required and the low hourly production rate. There are eight individual combing heads which have in total eight feed devices, eight fixed-position nipper assemblies, eight circular combs with comb segments, eight top combs and eight detaching devices. A particular problem is the discontinuous mode of operation of the combing heads. Additional disadvantages result from large mass accelerations and reversing movements, with the result that high operating speeds are not possible. Finally, the considerable amount of machine vibration results in irregularities in the deposition of the combed sliver. Moreover, the ecartement, that is to say the distance between the nipper lip of the lower nipper plate and the clamping point of the detaching cylinder, is structurally and spatially limited.

It is an aim of the invention to provide an apparatus of the kind described at the beginning which avoids or mitigates the mentioned disadvantages and which in a simple way, in particular, enables the amount produced per hour (productivity) to be substantially increased and an improved combed sliver to be obtained.

The invention provides an apparatus for the sorting or selection of a fibre structure comprising textile fibres which is supplied by means of a supply device to a sorting device, wherein the sorting device comprises:

at least one rotatably mounted roller, arranged downstream of the supply device, that rotates rapidly without interruption;

clamping devices which can clamp a portion of the fibre at a distance from its free end;

a mechanical combing device comprising at least one combing element which generates a combing action from the clamping site to the free end of the fibre in order to loosen and remove non-clamped constituents from the free end;

wherein the clamping devices are provided on said at least one rotatably mounted roller distributed spaced apart in the region of the roller periphery, and the at least one combing element is associated with the periphery of the roller.

By implementing the functions of clamping and moving the fibre bundles to be combed-out on a rotating roller, high operating speeds (nip rates) are achieved—unlike the known apparatus—without large mass accelerations and reversing movements. In particular, the mode of operation is continuous. When a high-speed roller is used, a very substantial increase in hourly production rate (productivity) is achieved which had previously not been considered possible in technical circles. A further advantage is that the rotary rotational movements result in a calming of vibration as well as more uniform movement sequences of the machine and accordingly in an improved combed sliver. The ecartement is advantageously not limited structurally. Moreover, the feed quantity of the incoming fibre lap is increased as a result and the separation of long-fibres is reduced.

The clamping devices advantageously cooperate with the means for generating a combing action (combing elements). Advantageously, the means for generating a combing action (combing elements) are located opposite the periphery of the roller. Advantageously, there is a space between the means for generating a combing action (combing elements) and the clamping devices. Advantageously, there is a space between the means for generating a combing action (combing elements) and the periphery of the roller. Advantageously, during combing-out the fibre sliver being combed out is in engagement with a clamping device and with a means for generating a combing action (combing element). The supply arrangement for the rotating roller may in some embodiments comprise a top comb roller. The supply arrangement may instead or as well comprise one or more of: a roller having clothing, needles or the like; a comb circulation element; two endlessly circulating belts; at least two feed rollers; or a slow-speed feed roller and a feed table. In certain embodiments, the supply arrangement may be formed from a drafting system. Advantageously, a top comb is arranged between the supply arrangement and the rotatable roller. Advantageously, the supply arrangement is fixed. Advantageously, the supply arrangement conveys the fibre lap continuously. Advantageously, means are provided to separate the fibre sliver delivered by the supply arrangement step-wise into individual fibre tufts. Advantageously, the means for creating individual fibre tufts comprise the rotatably mounted first roller. Advantageously, the rotatably mounted roller is provided with first clamping devices distributed spaced apart around its periphery, which preferably each have a nipper device. Preferably, there are means for transferring the fibre tufts to the subsequent sorting device (combing device). Preferably, the first roller serves for transferring the fibre tufts to the subsequent fibre-sorting device (combing device). Advantageously, when transferring the fibre tufts the first clamping elements and second clamping devices of a second roller cooperate. Advantageously, a rotatably mounted second roller is associated axially parallel to the first roller. In certain embodiments, the first roller and the second roller rotate in opposite directions to one another. Advantageously, the second roller is provided with second clamping devices distributed spaced apart around its periphery, the second clamping devices each advantageously having a nipper device. With respect to the first and/or second roller, the nipper devices may have a rotatably or displaceably mounted gripping element (upper nipper) and/or a fixedly mounted counter-element (lower nipper). The nipper devices may have a fixedly mounted counter-element (lower nipper). Advantageously, the counter-element (lower nipper) is movably mounted. Advantageously, the gripping element (upper nipper) is loaded by a force element, for example by a spring. Advantageously, the movably mounted counter-element (lower nipper) is force-loaded, for example by a spring. Advantageously, there is a relative movement between the nipper devices of the first roller and the supply arrangement. Advantageously, the second clamping devices cooperate with the means for generating a combing action. Advantageously, the means for generating a combing action are arranged at a distance from the outer periphery of the second roller. Advantageously, the second clamping devices co-operate with the means for generating a combing action. Advantageously, the means for generating a combing action are arranged at a distance from the outer periphery of the second roller. The means for generating a combing action may be of any suitable kind. For example, the means for generating a combing action may have endlessly circulating comb elements (revolving top). In that case, the comb elements run in the same direction as the clamped fibre bundles. It is preferred that the speed ratio between the second roller (combing rotor) and the comb top circulation is greater than 1.

In another advantageous embodiment, the means for generating a combing action have at least one rotating circular comb (circular comb rollers). The circular comb may have combing elements around its periphery. The circular comb may have circular comb rollers equipped with needles or the like around their periphery.

Advantageously, the second roller is associated with a take-off device. Preferably, there is a rotatably mounted take-off roller axially parallel to the second roller (combing rotor). The take-off roller may be provided with a clothing or the like on its outer periphery. Advantageously, the outer cylindrical surface of the take-off roller has air-passage openings. Advantageously, the interior of the take-off roller is connected to a source of negative pressure. In practice, it may be advantageous for a portion of the inner cylindrical surface of the take-off roller to be sealed by a screen element. Advantageously, the take-off roller is used for piecing the combed fibre tufts. Preferably, at least two fibre tufts are arranged to be supplied to the sorting device. Preferably, the fibre tufts are arranged to be supplied one after another to the fibre-sorting device. Preferably, a drafting device is arranged downstream of the take-off roller. As well, or instead, a sliver-deposition device may be arranged downstream of the take-off roller. In certain preferred arrangements, a drive device, for example a motor, is provided for moving the clamping devices, for example the upper nipper. It is preferred for a cam gear, for example a cam disc gear, to be arranged between the drive device, for example a motor, and the clamping devices. Preferably, at least one roller (supply roller, combing roller) is associated with a drive device, for example an electric motor. Preferably, the first roller and the second roller are drivable by a common gear. Advantageously, the drive device, for example an electric motor, drives the common gear.