Circular knitting machine

A circular knitting machine for producing knitted fabrics with combed-in fibers, comprising a needle cylinder, at least one carding device with a comb-in wheel and an extraction device for waste fibers, which produces knitted facbrics of a high quality and requires as little maintenance as possible. The extraction device has at least one extraction nozzle for generating a directional extraction flow.

The present disclosure relates to the subject matter disclosed in German
 Application No. 199 25 171.1 of Jun. 1, 1999, the entire specification of
 which is incorporated herein by reference.
 The invention relates to a circular knitting machine for producing knitted
 fabrics with combed-in fibers, comprising a needle cylinder, at least one
 carding device with a comb-in wheel and an extraction device for waste
 fibers.
 A circular knitting machine of this type is known from EP 0 742 852 B1.
 Such circular knitting machines are used to work clusters of fiber bands
 (sliver clusters) into knit loops.
 Proceeding from this state of the art the object underlying the invention
 is to provide a circular knitting machine which produces knitted fabrics
 of a high quality and requires as little maintenance as possible.
 This object is accomplished in accordance with the invention, in the
 circular knitting machine specified at the outset, in that the extraction
 device has at least one extraction nozzle for generating a directional
 extraction flow.
 By providing an extraction nozzle, the extraction flow may be directed and,
 in particular, those areas of the circular knitting machine, in which more
 waster fibers are generated, may be acted upon with the extraction flow.
 Such an area is, in particular, the comb-in area, in which a needle hook
 of a knitting needle removes a cluster of fibers from the comb-in wheel.
 The mechanical action of this needle hook on the fibers can lead to the
 detachment of fiber particles. Since detached fiber particles, on the one
 hand, settle in the circular knitting machine and soil it and, on the
 other hand, fall onto the knitted fabric and may reduce the quality of the
 knit, the extraction device is provided for extraction. In the device of
 EP 0 742 852 B1, the extraction device is of a funnel-shaped design with
 one end open downwards so that no selective direction of the extraction
 flow is possible but only a type of "global" suction effect occurs. With
 this device known from the state of the art waste fibers cannot,
 therefore, be carried away to an adequate and also precise extent. This
 problem is solved by the inventive extraction nozzles.
 The inventive extraction device may be used particularly advantageously
 when the circular knitting machine comprises an air flow guiding device
 for orienting fibers in an orientation air flow. The air flow guiding
 device also serves to work the free ends of the fiber clusters into the
 stitch or loop fabric. As a result, a fiber-band, high-pile knitted fabric
 with reversed fiber cluster loops can, in particular, be produced.
 As a result of the orientation air flow, bundles of fibers are oriented for
 working into a knitted fabric at their free ends. Two types of fluid flows
 are therefore effective in such a circular knitting machine, namely the
 extraction flow and an orientation air flow. In the device known from EP 0
 742 852 B1 the orientation air flow is affected by the extraction flow
 since the latter is non-directional and acts globally on a knitting area.
 In the case of the inventive device, on the other hand, the extraction
 flow may be directed and then only those areas, in which waste fibers
 occur, are selectively acted upon locally.
 It is, therefore, particularly favorable when the extraction nozzle or
 extraction nozzles are arranged and designed in such a manner that the
 respective extraction flow is essentially decoupled from the orientation
 air flow. As a result, the orientation air flow remains unaffected by the
 extraction flow and the quality of the take-up of the clusters of fibers
 is increased in comparison with the device known from the state of the
 art.
 It is favorable to have an extraction nozzle associated with each carding
 device. As a result, waster fibers are taken away from their main source
 and a uniform take-up results for each carding device. It is particularly
 advantageous when an extraction nozzle is associated with each comb-in
 wheel since the waste fibers result, in particular, at the comb-in wheel.
 In order to act on a comb-in wheel selectively with an extraction flow, a
 longitudinal axis of the extraction nozzle associated with the comb-in
 wheel is, advantageously, essentially at right angles to an axis of
 rotation of the comb-in wheel so that no cross flows occur.
 Furthermore, it is particularly advantageous when the longitudinal axis of
 the extraction nozzle is located in a plane of symmetry of the comb-in
 wheel essentially at right angles to the axis of rotation of the comb-in
 wheel. This results in an optimum alignment of extraction nozzle and
 comb-in wheel.
 In order to improve the extraction of fiber particles even more, the
 extraction flow is favorably directed in the same direction as the
 rotation of the comb-in wheel. As a result, waste fibers loosened from a
 needle hook are extracted directly and cannot settle at inaccessible
 locations. Again, waste fibers which are only partially detached and which
 could become completely loosened during further rotation of the comb-in
 wheel and then settle in inaccessible areas of the circular knitting
 machine are, in certain circumstances, loosened entirely by the assisting
 effect of the extraction flow so that they cannot settle in the machine.
 It is particularly favorable when an extraction nozzle is arranged and
 designed such that the effective area of the extraction flow covers a
 comb-in area of the comb-in wheel in order to act selectively on one of
 the main sources of waste fibers with the extraction flow.
 An extraction nozzle is favorably arranged and designed such that a lower
 area of the comb-in wheel facing the needle cylinder is acted upon by the
 extraction flow. On the one hand, this makes a complete detachment of
 partially loosened waster fibers possible; on the other hand, the
 extraction flow is still directed as a result since the area which has to
 be acted upon is not too large.
 In order to extract waste fibers as completely as possible from the comb-in
 area, the width of a nozzle opening is advantageously greater than the
 width of the associated comb-in wheel. The width of a nozzle opening is
 favorably somewhat greater than the width of an associated comb-in wheel,
 for example, in the order of magnitude of 5 to 10%. The extraction flow is
 still directed and covers the comb-in area well.
 A nozzle opening of an extraction nozzle is favorably arranged at an angle
 to a horizontal plane. As a result, the extraction flow is directed at an
 angle upwards and, in particular, may be formed essentially tangential to
 the comb-in wheel. This makes a good discharge of waste particles
 possible.
 It is favorable when an extraction nozzle comprises an aperture element and
 a connecting element, wherein the aperture element has the same
 cross-sectional area as the connecting element. As a result, the aperture
 may, on the one hand, be adapted such that a desired area is acted upon by
 the extraction flow; on the other hand, the suction capacity is not
 reduced as a result. The cross section of the aperture element is
 favorably broadened in a horizontal direction in comparison with the
 connecting element since in this way, in particular, the comb-in area can
 be well acted upon by an extraction flow.
 In a particularly favorable variation of one embodiment the inventive
 circular knitting machine has a plurality of carding devices, wherein each
 carding device comprises its own air flow means for orienting the fibers
 to be combed in. In this way, large areas of knitted fabric may be
 produced in an effective manner.
 So far, no comments have been given concerning the design of the air flow
 means. An air flow means favorably has at least one suction element and at
 least one blower element. Free ends of clusters of fibers may be drawn in
 by the suction element so that the cluster of fibers can be grasped by a
 needle hook. This effect can likewise be achieved by a blower element
 which orients the free ends of the cluster of fibers by means of its blast
 air flow; the two flows can also interact to increase the effect.
 The air flow means favorably comprises a take-up air flow means, with which
 a suction element and a blower element are arranged so as to face one
 another. This take-up air flow means serves to orient the free ends of the
 combed-in clusters of fibers in the air flow so that they can be grasped
 by a needle and can be worked into the loops. By providing a suction
 element and a blower element, which are arranged so as to face one
 another, the blast air flow and the suction air flow reinforce one another
 so that a particularly good orientation of the free fiber ends is
 achieved.
 For this purpose, an air flow of the suction element is favorably conducted
 outwards away from a central axis of the circular knitting machine and an
 air flow of the blower element is conducted outwards away from a central
 axis of the circular knitting machine in order to orient the free fiber
 ends outwards.
 It is particularly advantageous, when several types of fibers, for example,
 several colors (jacquard pattern) are intended to be worked in, that the
 inventive circular knitting machine comprises a plurality of feed systems
 for fibers and threads, wherein a feed system comprises n carding devices
 for the take-up of n types of fibers in loops. Each carding device is then
 provided for combing in one type of fibers.
 It is particularly favorable when a blower element is arranged between
 adjacent carding devices of the feed system. If a first type of fibers is
 combed in and the needle cylinder rotates further, there is the risk of
 these combed-in fibers becoming caught on the comb-in wheel of the next
 carding device and, in particular, its card clothing. As a result of the
 blower element, the fibers combed in in the first carding device may be
 oriented such that they come into contact essentially during the rotation
 of the needle cylinder without contact to the comb-in wheel or the fibers
 of the adjacent carding device (in the direction of rotation of the needle
 cylinder) which are to be combed in; the fibers already combed in can be
 "pulled through" under the adjacent carding device due to orientation by
 the blower element. It is then particularly favorable when, in relation to
 a comb-in area, the blower element is arranged outwards relative to a
 central axis of the circular knitting machine. The blast air flow for
 orienting the combed-in fibers of the first type of fibers may then be
 oriented contrary to the air flow for the take-up of all the fibers. In
 this way, during the "pulling through" of the combed-in first fibers under
 the comb-in wheel of the second fibers the free ends are "out of the way"
 of the needle hook which must comb in the fibers of the second type of
 fibers in the comb-in area of the second carding device for this second
 type of fibers. An air flow of the blower element is advantageously
 directed inwards in the direction of a central axis of the circular
 knitting machine.
 A particularly good knitting result is achieved when a suction element and
 a blower element are arranged so as to be oppositely located between
 adjacent carding devices of adjacent feed systems. As a result, the fibers
 may be oriented together as a last operating step in an operating cycle
 for the take-up of various types of fibers in loops and can be grasped and
 worked in by a needle hook.
 An extraction nozzle is favorably associated with each carding device.
 It is favorable when the extraction nozzles are each arranged between
 adjacent blower elements. As a result, it is possible in a
 constructionally simple manner for the extraction flow to be discharged
 and the comb-in area to be acted upon essentially completely.
 It is particularly advantageous when the extraction nozzles open into a
 suction chamber. The suction chamber makes the required vacuum for all the
 extraction nozzles available and it is then not necessary for each
 extraction nozzle to be connected individually to a vacuum generator.
 The extraction nozzles favorably open into a lower end surface of the
 suction chamber so that this does not take up any unused space.
 The suction chamber is advantageously designed so as to be rotationally
 symmetrical in order, in particular, to have the effect that no "dead
 areas" can form in it, in which waste fibers could be deposited.
 It is particularly favorable when an axis of the suction chamber coincides
 with the central axis of the circular knitting machine.
 A particularly simple construction of the inventive circular knitting
 machine may be achieved in that an air discharge means of a suction
 element of the air flow guiding device is connected to the suction
 chamber. As a result, the suction chamber may be used at the same time for
 the discharge of fiber particles and for generating the necessary vacuum
 in order to generate a suction air flow.
 A nozzle opening of an extraction nozzle is favorably arranged so as to be
 set back in a radial direction in relation to needles held on the needle
 cylinder in order to have a good discharge of waste fibers generated in
 the comb-in area.
 In order to avoid any effect on the orientation air flow and the extraction
 flow to a great extent in a vertical direction, as well, a lower end of a
 nozzle opening of an extraction nozzle is favorably arranged in vertical
 direction above an aperture opening of a blower element of the air flow
 guiding device.
 In order to prevent waste fibers from penetrating corresponding machine
 areas, a seal is favorably arranged between an extraction nozzle and a
 carding device.

One embodiment of an inventive circular knitting machine, which is
 illustrated schematically in FIG. 1 and is designated as a whole as 10,
 comprises a needle cylinder 12 which is rotatably mounted and holds
 knitting needles 14 (FIGS. 2, 3).
 A plurality of carding devices, which are each designated as a whole as 18,
 are arranged in a ring shape around a central axis 16 of the circular
 knitting machine 10, wherein carding devices adjacent in circumferential
 direction are spaced from one another (FIG. 4). A carding device comprises
 a sliver intake 20, a supply roller 24 driven via a drive means 22, for
 example, a step motor, a separating wheel 28 arranged after the supply
 roller 24 in relation to a sliver introduction direction 26, a working
 wheel 30 which is provided with a card clothing (not shown in the Figures)
 and comb-in wheel 32. The comb-in wheel 32 is provided with a card
 clothing 34 (FIG. 3).
 A drive means 36, for example, a cardan drive is provided for driving the
 separating wheel 28, the working wheel 30 and the comb-in wheel 32. The
 transfer of the driving force to the specified wheels 28, 30 and 32 may be
 brought about via a drive belt 38, wherein corresponding deflecting
 rollers 40, 42, 44 are then provided.
 The carding device 18 has a housing 46 which is open in a lower area 48
 facing the needle cylinder 12 so that a needle hook 50 of a knitting
 needle 14 can take up clusters of fibers to be combed in from the card
 clothing 34 of the comb-in wheel 32.
 Each carding device 18 is aligned radially to the central axis 16, wherein
 the respective axes of rotation of the supply roller 24, the separating
 wheel 28, the working wheel 30 and, in particular, the axis of rotation 51
 of the comb-in wheel 32 are at right angles to the radial direction and
 thus also at right angles to the plane defined by the central axis 16 and
 the radial direction.
 An extraction device 53 for waste fibers 55 (FIG. 3) is provided with a
 funnel-like exhaust hood 52 which is preferably arranged so as to be
 rotationally symmetrical about the axis 16 and the lower end of which is
 at a vertical distance from the needle cylinder 12 and extends upwards
 with a conical area 54, wherein a cylindrical area 56 adjoins the conical
 area 54. This cylindrical area preferably extends beyond the height of the
 inventive circular knitting machine 10 and is connected to a vacuum
 generator (not shown in the Figures). In this way, a suction chamber 58 is
 formed in the interior of the exhaust hood 52.
 The exhaust hood is closed at its lower end 60 facing the needle cylinder
 12, wherein it does, however, have at this point, in the vicinity of its
 edge, openings 62 which themselves are arranged in a ring shape around the
 axis 16 and wherein such an opening 62 is associated with each carding
 device 18.
 An extraction nozzle 64 is arranged at each opening 62 so that an
 extraction nozzle 64 is associated with each carding device 18, wherein
 this nozzle is oriented towards the respective comb-in wheel 32 of the
 carding device 18. Such an extraction nozzle 64 extends from the lower end
 60 of the exhaust hood 52 downwards in the direction of the needle
 cylinder 12 and in a radial direction away from the axis 16 so that a
 longitudinal axis 66 of the extraction nozzle 64 forms an angle to a
 horizontal plane 67 at right angles to the central axis 16. The
 longitudinal axis 66 of the respective extraction nozzle 64 is thereby
 located in a plane of symmetry of the associated comb-in wheel 32 which is
 the plane defined by the radial direction and the central axis 16.
 Consequently, the extraction nozzle is arranged such that its longitudinal
 axis 66 is at right angles to the axis of rotation 51 of the associated
 comb-in wheel 32.
 A nozzle opening 68 is likewise arranged at an angle to this horizontal
 plane 67 so that an extraction flow, which flows away via the extraction
 nozzle 64 into the suction chamber 58, is at an angle to this horizontal
 plane. The extraction nozzle 64 is preferably arranged and designed, i.e.
 the respective angles of the longitudinal axis 66 to the horizontal plane
 67 and of the nozzle opening 68 to the horizontal plane 67 are selected
 such that this extraction flow is tangential to the comb-in wheel 32.
 As illustrated in FIGS. 4 and 5, an extraction nozzle 64 comprises an
 aperture element 70 with the nozzle opening 68 and a connecting element 72
 which adjoins the aperture element 70 and provides the connection to the
 opening 62 in the lower end 60 of the exhaust hood 52. At least in the
 area of the nozzle opening 68 the aperture element has a somewhat greater
 cross-sectional width in a horizontal direction (i.e. parallel to the
 horizontal plane 67). This corresponds to a direction at right angles to
 the plane of drawing of FIGS. 1 to 3. The cross-sectional area is the same
 over the length of the nozzle and so the same suction capacity results
 over its entire length.
 The nozzle opening 68 is directed onto a comb-in area 74 (FIG. 3) such that
 the effective area of an extraction flow flowing away through the
 extraction nozzle 64 into the suction chamber 58 covers this comb-in area,
 at which the sliver is combed into the needle hook 50.
 In addition, the inventive circular knitting machine 10 has an air flow
 guiding device which is designated in FIG. 1 as a whole as 76. This
 comprises a plurality of air flow means 78, the number of which
 corresponds to the number of feed systems 110 for fibers and threads (FIG.
 4). A feed system for the take-up of n types of fibers comprises n carding
 devices, i.e. one comb-in wheel per type of fibers.
 An air flow means 78 itself comprises a suction element designed as a
 suction nozzle 80 and a blower element designed as a blast nozzle 82 which
 are arranged so as to be radially aligned with one another, wherein an
 effective zone 88 is formed between a respective aperture opening 84 of
 the suction nozzle 80 and an aperture opening 86 of the blast nozzle 82;
 an orientation air flow 89 can flow in this effective zone and serves for
 the orientation of free ends of clusters of fibers already combed into
 loops on one side. In the effective zone 88, the needle hook 50 of a
 knitting needle 14 is displaceable in vertical direction.
 Furthermore, the air flow means 78 of a feed system 110 comprises an
 additional blast nozzle 112 which is arranged between adjacent carding
 devices 18 of a feed system 110.
 In the embodiment shown in FIG. 4, which serves to produce a two-colored
 jacquard pattern, a feed system 110 comprises two carding devices, wherein
 the first carding device 114 serves to comb in a first type of fibers with
 a first color and the adjacent second carding device 116 for combing in a
 second type of fibers with a second color. In relation to the central axis
 16, the blast nozzle 112 is arranged between these two carding devices 114
 and 116 such that its blast air flow acts inwardly.
 The suction nozzle 80 has a discharge means 90, for example, a suction line
 which leads into the cylindrical area 56 of the suction chamber 58 via
 connections 92 in order to generate a suction air flow of the orientation
 air flow.
 The connections 92 are preferably arranged so as to be oriented downwards
 at an angle to the central axis 16 so that a suction air flow flows into
 the cylindrical area 56 of the exhaust hood 52 at an angle and thus has
 only a small flow component in a horizontal direction. This also prevents
 part of the extraction flow, which contains waste particles or fibers,
 from flowing into the discharge means 90 in a reverse direction.
 The blast nozzle 82 has a supply means 94, for example, a supply line which
 is connected to a pressure generator 96 for generating a blast air flow of
 the orientation air flow.
 The aperture opening 86 of the blast nozzle 82 is preferably arranged in
 relation to the aperture opening 84 of the suction nozzle 80 such that a
 blast air flow can also be discharged essentially completely through the
 suction nozzle 80 so that no "stray air flows" occur.
 The extraction nozzles 64 are arranged relative to the air flow means 78 in
 accordance with the invention such that the extraction flow, which acts
 upon the comb-in area 74 with a vacuum, essentially does not affect the
 air flow of the adjacent air flow means 78. For this purpose, the
 individual extraction nozzles 64, which are associated with the comb-in
 wheels 82 of the associated carding device 18, are each arranged between
 the air flow means 78 in circumferential direction in relation to the
 central axis 16. Since the suction nozzle 80 and blast nozzle 82 of such
 an air flow means are arranged so as to be radially aligned, the
 extraction nozzles 64 are oriented in a radial direction--like the
 associated comb-in wheel 32.
 The nozzle opening 68 is set back in comparison with the blast nozzle 82 in
 relation to the radial direction.
 The width of the nozzle opening 68 on the aperture element 70 corresponds
 essentially to the width of the associated comb-in wheel 32, wherein the
 width of the nozzle opening 68 is somewhat larger so that it is ensured
 that the extraction flow covers the entire width of the comb-in wheel 32
 and a certain area outside it. As a result, care is also taken that the
 extraction flow cannot pass into the area of the suction and blast air
 flows of the adjacent suction nozzles 80 and blast nozzles 82 in a
 circumferential direction.
 A lower end 98 of the nozzle opening 68 of the respective extraction nozzle
 64 is arranged at a vertical distance to the blast nozzle 82 so that it is
 also ensured in this way that the extraction flow also does not affect the
 blast air flow with respect to this direction. This vertical distance is
 selected such that a lower area 100 of the comb-in wheel 32 can be acted
 upon with the extraction flow and, in particular, an extraction zone can
 be formed between, in relation to the vertical direction, knitted fabrics
 (not shown in the Figures) and the respective comb-in wheel 32, this zone
 being such that it comprises the comb-in area 74 and an area extending
 from the knitting needle 14 inwards in the direction of the central axis
 16.
 A seal 102 is preferably arranged between each extraction nozzle 64 and the
 housing 46 of the respective carding device 18 and this seal, in
 particular, prevents waste fibers from passing into the area behind the
 seal. The seal 102 can be a separate sealing element or also a housing
 element of the housing 64 which is connected sealingly to an upper surface
 of the extraction nozzle 64.
 The inventive circular knitting machine operates as follows:
 The sliver (fiber band) is supplied to each carding device 18 via the
 respective sliver intake 20, drawn through this carding device, separated
 into individual fibers in the separating wheel 28, evened out when
 required by the working wheel 30 and, in the comb-in wheel 32, oriented
 parallel to the combing in by the respective needle hook 50 by the card
 clothing 34.
 During the circulation of the sliver at the comb-in wheel and, in
 particular, due to the engagement of the needle hook 50 for the combing
 in, individual fiber components 55 become loosened. These cause soiling of
 the circular knitting machine and can, in particular, be deposited on the
 knitted fabric, as a result of which the quality of the knitted fabric is
 diminished, for example, due to undesired color effects. As a result of
 the inventive extraction nozzles 64, the waste fibers 55 which result at
 the comb-in wheel 32 are extracted so that the soiling of the machine is
 reduced and, in particular, the quality of the knitted fabric is not
 diminished. The extraction flow 104, which is generated via the extraction
 nozzles 64, is preferably directed in the same direction as the rotation
 of the comb-in wheel 32 in order to achieve a good extraction effect. The
 extraction flow, which is composed of air and waste fibers, is discharged
 via the exhaust hood 52.
 The clusters of fibers combed into the needle hooks 50 serve as sliver
 fibers which are to be tied up into loops. A guidance of the threads for
 the loops takes place in an area 118 which is shown in FIG. 4. For this
 purpose, a cluster of fibers combed into a needle hook 50 and thus grasped
 by the needle hook 50 is worked into the loops in a manner known per se
 with its gripping area grasped by the needle hook 50 (cf., for example, DE
 28 17 130 C2, EP 0 742 852 B1). A cluster of fibers worked in in such a
 manner has free ends.
 In the case of the embodiment shown in FIG. 4, two different types of
 fibers, for example, pile fibers can be worked in in order to generate,
 for example, a two-colored jacquard pattern. For this purpose, fibers of
 the first type of fibers are combed in in the comb-in area 74 of the first
 carding device 114. By rotating the needle cylinder further in the
 direction 120 this combed-in cluster of fibers passes into the area of the
 second carding device 116. To avoid the combed-in fibers being grasped by
 the corresponding comb-in wheel of the second carding device 116, the
 blast air flow of the blast nozzle 112 orients the fibers already combed
 in such that these do not project upwards and thus pass through under the
 second carding device 116 essentially without contact with the comb-in
 wheel 32 of the carding device 116 during the rotation of the needle
 cylinder 12. The orientation with the blast air flow also sees to it that
 the free ends are oriented in the direction of the central axis 16 of the
 circular knitting machine and so the needles, in particular, which are
 intended to grasp clusters of fibers of the second type of fibers at the
 comb-in wheel 32 of the second carding device 116, do not grasp the fibers
 of the first type of fibers which have already been combed in.
 When the needle cylinder is rotated further, the combed-in clusters of
 fibers of the first type of fibers and of the second type of fibers pass
 into the area of the take-up air flow guiding means associated with the
 corresponding feed system 110 and, in particular, into the area of the
 suction air flow of the suction nozzle 80 and of the blast air flow of the
 blast nozzle 82. As a result of this orientation air flow the free ends
 are then oriented so that a needle hook 50 can grasp them and can likewise
 work them into the loops. They are then cast off (area 122 in FIG. 4). At
 the end of this take-up process the clusters of fibers no longer have any
 free ends with respect to the loops.
 As a result of providing extraction nozzles 64 in accordance with the
 invention it is possible for the extraction flow to leave the suction and
 blast air flows for orienting the clusters of fibers during their take-up
 into the loops and the orientation flow for preventing the grasping of
 combed-in fibers by adjacent carding devices essentially unaffected and so
 no changes need be made by the inventive circular knitting machine with
 respect to the take-up method for the clusters of fibers into the loops in
 comparison with known devices but the knitted fabric has a better quality
 since waste fibers are kept away from the knitted fabric to a great extent
 by the inventive extraction nozzles 64.