FIBRE METERING ARRANGEMENT

Abstract: There is disclosed a fibre metering arrangement (11) adapted for feeding fibre to a fibre utilising arrangement (13) comprising at least first and second fibre feeding units (14, 15), spaced apart in the direction of fibre feeding so that the second (15) is downstream with respect to the first (14) and independently driven at relatively variable fibre feeding speeds each having weight transducer means (14b, 15b) sensitive to the weight of fibre being fed by that unit and the speed of each unit being controlled in accordance with the weight of fibre sensed by its associated transducer means.

Description: FIBREMETERINGARRANGEMENT This invention relates to a fibre metering arrangement, for feeding fibre to a fibre utilising arrangement such for example as a carding machine preparing a card web such as might be utilised, perhaps after cross-folding, in a non-woven fabric producing operation such as a stitch bonding operation. It is a problem to supply the carding machine with fibre at a constant rate. Irregular fibre supply results in an uneven web which is manifest as density variation in a non-woven fabric produced from it. The carding machine feeding arrangement withdraws fibre from a static supply such as a hopper in which a "head" of fibre is maintained within height limits by a controlled bale opening arrangement. A roller or lattice, which may be spiked, picks fibre from the bottom of the "head" in the hopper. Since the "head" is variable at least to some extent and since the fibre density in the hopper is not homogeneous, the roller or lattice will pick up fibre at a variable rate and unless countermeasures are taken this variable rate will be reflected in variations at the carding machine input. Various measures have been proposed to deal with this problem involving weighbelts and weighplates over which the fibre passes en route to the carding machine and which control the speeds of rollers which take fibres from the weighbelt or plate so that if the weight is low the take off roller speed is increased and vice versa in an effort to level out the rate of feed to the card. These measures do not, however, solve the problem inasmuch as card web still exhibits unevenness attributable to fibre input rate variation, and it is still difficult precisely to control web weight to a desired degree of accuracy. The present invention provides improved fibre metering arrangements that address these problems. The invention comprises a fibre metering arrangement adapted for feeding fibre to a fibre utilising arrangement comprising at least first and second fibre feeding units spaced apart in the direction of fibre feeding so that the second is downstream with respect to the first and independently driven at relatively variable fibre feeding speeds each having weight transducer means sensitive to the weight of fibre being fed by that unit and the speed of each unit being controlled in accordance with the weight of fibre sensed by its associated transducer means. The speed of the first unit may be controlled also in accordance with the weight of fibre sensed by the transducer means of the second unit. The speed of the second unit may be controlled also in accordance with the speed and the weight of fibre sensed by the transducer means of the first unit. The first and second units may be components of a series of such units. Adjacent units of the series may be interrelated as first and second such units. The first feeding unit may comprise rollers both ahead of (in the direction of feeding) and following the second feeding unit. The first feeding unit may comprise two rollers ahead of and at least one roller following the second feeding unit which may itself comprise two rollers. The arrangement may be adapted to withdraw fibre from a static supply, i.e. the roller or lattice aforementioned that withdraws fibre from the static supply may be a part of the arrangement and within the control philosophy. Each unit may comprise a driven roller (or rollers) . The unit speeds and weight transducer outputs may be inputs to a neural network adapted or trained to control the unit speeds to give a constant fibre feed rate to the fibre utilising arrangement. In another aspect, the invention comprises a fibre metering arrangement adapted for feeding a fibre fleece to a fibre utilising arrangement comprising a fibre fleece feeding unit having first weight transducer means sensitive to the weight of fibre being fed by that unit and being driven at a variable speed dependent on the weight of fleece sensed by said first transducer means with a fine delay equivalent to the time taken for the fleece to pass from the said unit to an input to the fibre utilising arrangement to ensure a controlled rate of fibre utilisation. The said first weight transducer means may be sensitive to the weight of a small lengthwise extent of fleece. The arrangement may have additional fibre fleece feed means having associated weight transducer means. Said additional feed means may feed and said associated weight transducer means may be sensitive to the weight of a longer lengthwise extent of fleece than said first weight transducer means. Said associated weight transducer means may be sensitive to the weight of a lengthwise extent of fleece including the weight to which said first weight transducer means are sensitive. Said associated weight transducer means may effect control on the rate at which the input to the fibre utilising means inputs fleece to the said fibre utilising means. Said associated weight transducer means may effect control on the rate at which fleece is taken from a source of fibre to be fed to the fibre utilising means. Said source of fibre may comprise a hopper. The arrangement may be adapted to control the rate of supply of fibre to the hopper to tend to maintain a constant head or level of fibre in the hopper. The invention in another aspect comprises a fibre metering arrangement adapted for feeding fibre to a fibre utilising arrangement comprising a hopper into which fibre is fed at the top and transfer means transferring fibre from below the level of fibre in the hopper to the fibre utilising arrangement and control means controlling the rate at which fibre is fed into the hopper to maintain the head or level of fibre substantially constant above the level at which the transfer means takes fibre from the hopper. Embodiments of fibre metering arrangements according to the invention will now be described with reference to the accompanying drawings, in which :- Figure 1 is a diagrammatic illustration of a two-unit arrangement; Figure 2 is a diagrammatic arrangement of a three-unit, four rollers arrangement; and Figure 3 is a diagrammatic illustration of another arrangement. Figures 1 and 2 of the drawings illustrate fibre metering arrangements 11 adapted for feeding fibre 12 to a fibre utilising arrangement - in each case a carding machine 13 producing a card web for utilisation in non-woven fabric manufacture or for the production of spun yarn. The fibre metering arrangements comprise at least first and second fibre feeding units 14,15 spaced apart in the direction of fibre feeding - indicated by the arrow so that the second unit 15 is downstream of the first unit 14. The units 14,15 are independently driven at relatively variable fibre feeding speeds by having electric motors 14a,15a for example stepper motors which can be speed controlled by controlling the rate of supply of energising pulses. Each unit 14,15 has weight transducer means 14b,15b sensitive to the weight of fibre being fed by that unit. The entire roller and motor assembly can be supported for example on load cells, or perhaps just the roller may be supported on load cells, the motor being separately mounted and connected to drive the roller through a flexible coupling or otherwise so that the connection of the roller to the motor does not substantially affect the weighing. The speed of each unit 14,15 is controlled by a controller 16 in accordance with the weight of fibre sensed by its associated transducer means. If, for example, the downstream, second roller 15 has a reduced fibre loading, as sensed by the transducer 15b, it can be arranged to increase in speed so as to increase the linear rate of supply of fibre to the carding machine 13 to compensate and maintain a constant mass of fibre per unit time. The increase in speed of downstream roller 15 will take fibre faster from roller 14 which in turn will experience a reduction in the weight of fibre being fed by it and speed up in response so as to maintain the fibre mass flow rate to roller 15. This will compensate for variations in the supply of fibre to the rollers 14,15 which variations are occasioned by the non-homogeneous nature of the fibre mass removed from a hopper 17 by a spiked lattice 18 (or equivalent means such as a spiked roller) . The hopper is fed with fibre freshly pulled from opened bales by a conventional spiked lattice arrangement controlled in accordance with the weight of fibre in the hopper 17 or the height the fibre reaches in the hopper 17 as may be sensed by a photoelectric arrangement. More sophisticated control techniques can be used. Thus the speed of the first, upstream unit 14 can also be controlled in accordance with the weight of fibre sensed by the transducer 15b of the second, downstream unit 15. The second unit 15 sensing it is light of fibre calls on the first unit 14 to feed faster. Of course, since the first unit 14 is also reacting to the fibre weight sensed by its own transducer 14b, should that transducer 14b register an increased weight, the unit will tend to slow down, and the result will be a balance between the demand signal from unit 15 and the supply signal from transducer 14b. The speed of the second, downstream unit 15 may also be controlled in accordance with the speed and the weight of fibre sensed by the transducer 14b. Thus if unit 14 was oversupplying fibre to unit 15, unit 15 could be retarded to anticipate the oversupply. Figure 1 illustrates an arrangement in which units 14 and 15 are fed directly from the lattice 12 and the speed of the lattice is controlled by the controller 16. This speed can also be controlled in accordance with the speeds and fibre weights on one or other or both of the units 14,15. Figure 2 illustrates an arrangement in which a coupled roller pair 19 having a single drive motor 19a and a single weighing transducer 19b is interposed between the lattice 12 and the first unit 14 and this may be regarded as another element of the metering arrangement functioning in the same way as units 14 and 15, so that units 19 and 14 may equally well be regarded as first and second units for purposes of the above description. The control philosophy can be implemented in the microprocessor or computer in the controller 16. If the speed of each roller is controlled solely by the weight of fibre on it, it will be necessary to predetermine the nominal fibre weight on the roller to yield a given card web weight at the nominal feed speed and to assign a value to a constant interconnecting a decrease in weight and an increase in speed, and to do that for each of the units. With more sophisticated control philosophies, constants will have to be assigned to the relationships between speed increase or decrease of one unit and weight decrease or increase of another unit. This process might be handled, instead, however, by a neural network in the controller 16 which could learn or be taught the constants as weightings for hidden units interconnecting input and output units so as to achieve the desired result of a constant rate of supply of fibre to the carding machine. The use of a series of feed units can in this way even out irregularities in weight/unit length of fibre fleece taken from the static supply in the hopper 17, the more units employed, the better the smoothing effect. If the lattice is also controlled, the feed rate can be precisely controlled as well. Figure 3 of the drawings illustrates a fibre metering arrangement 31 adapted for feeding a fibre fleece 32 to a fibre utilising arrangement 33 comprising a fibre fleece feeding unit 34 having first weight transducer means 35 sensitive to the weight of fibre being fed by the unit 34. The unit 34, as before, comprises a roller. Rollers, it should be remarked, are, perhaps surprisingly, particularly well suited as fibre, or fibre fleece, feeding units. They have inertial advantages over belts being more responsive to control. As elements of fibre weighing arrangements they have the advantage over belts that they are lighter in, as it were, "tare" weight, and, over weighplates, they exercise a feeding function that plates cannot. The roller 34 is driven, as before, by its own electric motor 34a at a variable speed dependent on the weight of fleece 32 sensed by the transducer means 35. The weight signal from the transducer means 35 is input to a control arrangement 36 to that end. However, the response of the motor 34a to a change-in-weight signal is delayed by the time taken for the fleece 32 to pass from the roller 34 to the input to the fibre utilising arrangement 33. The input to the fibre utilising arrangement is shown as a licker-in roll 33a. Such control ensures a controlled rate of fibre utilisation. The roller 34's transducer means 35 are sensitive to the weight of a small lengthwise (i.e. in the direction of fleece travel) extent of fleece 32, namely that between adjacent rollers 41,42. The control is therefore (as before) particularly sensitive to short term variations in fleece density. The arrangement has additional fibre fleece feed means namely rollers 41,42 or rather, as shown, groups of rollers 41,42. The rollers 41,42 are mounted on a support 43 which has associated weight transducer means 44. The additional feed means 41,42 feed and their associated weight transducer means 44 are sensitive to the weight of a longer lengthwise extent of fleece than said first weight transducer means 35; in fact, the roller 34 and transducer 35 are themselves mounted on the support 43 so that the transducer means 44 are sensitive to the weight of a lengthwise extent of fleece 32 - namely that between lattice 51 and the licker-in 33a - which includes the weight to which the roller 31 is subject and to which its transducer means 35 are sensitive. Thus the system is sensitive to the weight on all five rollers 41,42,35, the thus-sensed weight being used to control the overall rate of feed, while the roller 35 is sensitive to short-term variations and controlled so as to smooth those out within the overall feeding rate speed control. Situating the independently driven roller 34 in between the rollers 41,42, which are driven together, is particularly advantageous in the detection of short-term variations in linear weight of fleece as overfeeding the fleece 32 to the roller 34, or overfeeding the fleece 32 past the roller 34 to the roller 42 could tend to arch the fleece over the roller 34 leading to a reduced weight indication. This can be avoided by suitable control measures in the arrangement illustrated. The said associated weight transducer means 44 taken together with knowledge of the surface speed of the rollers 41,42 given an indication of the rate of mass transfer to the licker-in 33a and this can be used to effect control of the rate at which the input to the fibre utilising means - namely the licker-in 33a - inputs fleece to the utilising means 33 - in other words, effect control over the speed of the licker-in 33a. At the same time, control can be effected over the rate at which fleece 32 is taken from a source of fibre to be fed to the fibre utilising means, namely over the speed of the lattice 51 which takes fibre from the bottom of a hopper 52. The arrangement may also control the rate of supply of fibre to the hopper 52 to tend to maintain a constant head or level of fibre in the hopper 52 - this can be instead of or ancillary to a level control as described with reference to Figures 1 and 2. The arrangement effectively combines the advantages of a long fibre weighing zone for the control of the average rate of feed and of a short weighing zone for smoothing out short term variations in the overall rate. Over a wide system, the units can be split transversely into two or more independent units so as to control variations across the width of the card web. As illustrated the units comprise simple conveyor rollers operative to move the fibre by friction due to its weight. However any one or more of the units could include a nip roller arrangement for more positive control.

Claims: C AIMS. 1. A fibre metering arrangement adapted for feeding fibre to a fibre utilising arrangement comprising at least first and second fibre feeding units spaced apart in the direction of fibre feeding so that the second is downstream with respect to the first and independently driven at relatively variable fibre feeding speeds each having weight transducer means sensitive to the weight of fibre being fed by that unit and the speed of each unit being controlled in accordance with the weight of fibre sensed by its associated transducer means. 2. An arrangement according to claim 1, in which the speed of the first unit is controlled also in accordance with the weight of fibre sensed by the transducer means of the second unit. 3. An arrangement according to claim 1 or claim 2, in which the speed of the second unit is controlled also in accordance with the speed and the weight of fibre sensed by the transducer means of the first unit. 4. An arrangement according to any one of claims 1 to 3, in which the first and second units are components of a series of such units. 5. An arrangement according to claim 4, in which adjacent units of the series are interrelated as first and second such units. 6. An arrangement according to any one of claims 1 to 5, in which the first feeding unit comprises rollers both ahead of (in the direction of feeding) and following the second feeding unit. 7. An arrangement according to claim 7, in which the first feeding unit comprises two rollers ahead of and at least one roller following the second feeding unit. 8. An arrangement according to claim 6 or claim 7 , in which the second feeding unit comprises two rollers. 9. An arrangement according to any one of claims 1 to 8, adapted to withdraw fibre from a static supply. 10. An arrangement according to any one of claims 1 to 9, in which each unit comprises a driven roller. 11. -An arrangement according to any one of claims 1 to 10, in which the unit speeds and weight transducer outputs are inputs to a neural network adapted or trained to control the unit speeds to give a constant fibre feed rate to the fibre utilising arrangement. 12. A fibre metering arrangement adapted for feeding a fibre fleece to a fibre utilising arrangement comprising a fibre fleece feeding unit having first weight transducer means sensitive to the weight of fibre being fed by that unit and being driven at a variable speed dependent on the weight of fleece sensed by said first transducer means with a time delay equivalent to the time taken for the fleece to pass from the said unit to on input to the fibre utilising arrangement to ensure a controlled rate of fibre utilisation. 13. An arrangement according to claim 12, in which the said first weight transducer means are sensitive to the weight of a small lengthwise extent of fleece. 14. An arrangement according to claim 12, or claim 13, having additional fibre fleece feed means having associated weight transducer means. 15. An arrangement according to claim 1 , in which said additional feed means and said associated weight transducer means are sensitive to the weight of a longer lengthwise extent of fleece than said first weight transducer means. 16. An arrangement according to claim 15, in which said associated weight transducer means are sensitive to the weight of a lengthwise extent of fleece including the weight to which the said first weight transducer means are sensitive. 17. An arrangement according to any one of claims 13 to 16, in which said associated weight transducer means effect control on the rate at which the input to the fibre utilising means inputs fleece to the said fibre utilising means. 18. An arrangement according to claim 16 or claim 17, in which the said associated weight transducer means effect control on the rate at which fleece is taken from a source of fibre to be fed to the fibre utilising means. 19. An arrangement according to claim 18, in which said source of fibre comprises a hopper. 20. An arrangement according to claim 19, adapted to control the rate of supply of fibre to the hopper to tend to maintain a constant head or level of fibre in the hopper. 21. A fibre metering arrangement adapted for feeding fibre to a fibre utilising arrangement comprising a hopper into which fibre is fed at the top and transfer means transferring fibre from below the level of fibre in the hopper to the fibre utilising arrangement and control means controlling the supply of fibre to the fibre utilising arrangement said control means controlling the rate at which fibre is fed into the hopper to maintain the head or level of fibre substantially constant above the level at which the transfer means takes fibre from the hopper.

Inventors: BARBER ROY MICHAEL, BARBER, ROY, MICHAEL
Applicants: BARBER ROY MICHAEL, GARNETT CONTROLS LTD, BARBER, ROY, MICHAEL, GARNETT CONTROLS LIMITED
Application year: 1995
Main classification: D01G23
IPC codes: D01G23