Card clothing for flats of a card

A card clothing for flats of a card with a carrier element and a plurality of card wires received with at least one received section in the carrier element, wherein each card wire has at least one processing section arranged exposed outside of the carrier element. At least in one of the card wires the received section received in the carrier element has at least the same length as the processing section which is exposed outside of the carrier.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a card clothing for flats of a card with a
 carrier element and a plurality of card wires received with at least one
 received section in the carrier element, wherein each card wire has at
 least one processing section arranged exposed outside of the carrier
 element. The invention also relates to a carrier element which can be used
 for manufacturing such a card clothing.
 2. Description of the Related Art
 A card is used in manufacturing yarn for parallelizing the individual
 fibers of a raw material consisting of inordinate fibers. For this
 purpose, a card usually is essentially composed of a swift formed
 essentially in the form of a circular cylinder and a number of flats which
 are movable along a predetermined path relative to the swift extending
 approximately parallel to the circumferential surface of the swift. For
 processing the fibers of the raw material, the swift has on its
 circumferential surface a swift clothing formed, for example, by sawtooth
 wires, while the flats are equipped with flat clothings along the
 predetermined path on the side facing the swift. These flat clothings can
 also be constructed in the form of sawtooth wire sections which extend
 parallel to the predetermined path. However, also used for this purpose
 are flat clothings in the form of card clothings of the above-described
 type. In comparison to the all-steel clothings formed of sawtooth wire
 sections, the card clothings of the above-described type are distinguished
 by a substantially lower weight and by significantly lower manufacturing
 costs. In this connection, the weight of a flat equipped with a card
 clothing of the above-described type may be less than half the weight of a
 flat with a flat clothing formed from sawtooth wires. This not only
 results in a significantly lower energy consumption when operating a card,
 but also in less wear because the movement and guidance of the flats
 equipped with a card clothing of the above-described type along the
 predetermined path can take place using particularly low forces. For this
 reason, particularly when manufacturing inexpensive yarns having low
 quality requirements, card clothings of the above-described type are
 increasingly used.
 However, it has been found problematic that the web-shaped carrier
 elements, which are composed of an elastic synthetic material and/or a
 plurality of fabric layers which are vulcanized together, tear already
 after a short time in the area of the received sections of the card wires.
 This is because, during the processing of the fiber material, substantial
 forces act on the carrier element in the area of the received sections of
 the card wires. For eliminating this deficiency, it has already been
 proposed in CH 636 134 to provide the carrier elements of card clothings
 of the above-described type with web-shaped reinforcement inserts.
 However, the manufacture of such carrier elements is comparatively very
 expensive, so that the cost reductions to be achieved by the use of these
 card clothings are at least partially eliminated.
 In addition, when using the card clothings of the above-described type, it
 has been found to be a disadvantage that a large quantity of short fibers
 accumulates in the area of the processing sections of the card wires; for
 ensuring a reliable operation of the card, this requires a frequent
 cleaning of the card clothings of the flats.
 SUMMARY OF THE INVENTION
 In view of the above-described problems in the state of the art, the
 invention is based on the object of providing an inexpensive and low-wear
 card clothing of the above-described type which is able to ensure a
 reliable operation of a card in a simple manner.
 In accordance with the present invention, this object is met by a further
 development of the known card clothings of the above-described type, in
 which at least in one of the card wires the received section received in
 the carrier element has at least the same length as the processing section
 which is exposed outside of the carrier.
 This invention is based on the finding that the substantial wear observed
 when using the known card clothings is primarily due to the lever length
 between the processing tip arranged at the end of the processing section
 facing the carrier element and the carrier element, wherein the lever
 length is large in comparison to the length of the received section
 available for transmitting the processing forces acting on the processing
 section to the carrier element. In the card clothing further developed in
 accordance with the present invention, the reduction of the length of the
 processing section to a length corresponding at most to the length of the
 received section results in a change of the force transmission ratio
 between the processing forces acting on the processing section of the card
 wires and the received section of the card wires available for introducing
 these processing forces into the carrier element, wherein this change of
 the force transmission ratio is advantageous with respect to the wear of
 the card clothing. Consequently, tearing of the carrier element in the
 area of the received sections of the card wires received in the carrier
 element can be reliably prevented in case of the usually occurring
 processing forces even without the use of additional reinforcement inserts
 in the carrier element. Therefore, the further development of the known
 card clothings according to the invention can ensure a high resistance to
 wear in an economical manner.
 Moreover, the reduction of the length of the processing sections
 additionally reduces the quantity of the short fibers accumulating during
 the operation of a card in the area of the card clothings according to the
 invention. This is due to the fact that generally only those short fibers
 can accumulate in the area of the card clothings whose length only
 slightly exceeds the length of the processing sections so that the
 reduction of the length of the processing sections results in a reduction
 of the short fiber portion separated by the card from the raw material.
 This result of the reduction of the length of the processing sections of
 the card wires proposed in accordance with the invention appears to be a
 disadvantage at first glance. However, it has been found, particularly
 when manufacturing inexpensive yarns with low quality requirements, that
 the reduced separation of short fibers and contamination from synthetic
 fibers with low contamination can be readily accepted in view of the
 advantages achieved as a result with respect to the infrequently required
 cleaning of the card clothings of the flats.
 With respect to the resistance to wear of the card clothings according to
 the invention, it has been found to be particularly advantageous if the
 ratio of the length of the received section of the card wires received in
 the carrier element to the length of the processing section exposed
 outside of the carrier element is at least 3:1, preferably at least 5:1.
 For reducing the quantity of the short fibers accumulating during the
 operation of a card in the area of the card clothings of the flats, it has
 been found particularly advantageous if the length of the processing
 sections exposed outside of the carrier element is shorter than 3 mm,
 preferably shorter than 2 mm, particularly preferably shorter than 1.5 mm.
 It has been found to be particularly advantageous with respect to
 production technology if the received sections of the card wires extend
 through the carrier element starting from the rear side of the carrier
 element facing away from the processing section to the front side of the
 carrier element facing the processing section; this is because, when
 manufacturing card clothings according to the invention, the card wires
 can then be inserted--without damaging the front side of the carrier
 element which generally faces the swift during the processing of the fiber
 material--to such an extent into the rear side of the carrier element
 until the processing section emerges at the front side of the carrier
 element.
 For securing the card wires in the carrier element, the card wires can be
 equipped at their ends of the received section facing away from the
 processing section with a holding section resting against the rear side of
 the carrier element. In this connection, it has been found to be
 particularly advantageous if the card wires have two processing sections
 located exposed outside of the carrier element as well as two received
 sections penetrating the carrier element, wherein the received sections
 are connected to each other through a connecting section resting against
 the rear side of the carrier element. For example, such card wires can be
 constructed essentially U-shaped, wherein each of the two outer sides of
 such a U-shaped card wire has a processing section exposed outside of the
 carrier element and a received section received in the carrier element and
 the leg of the card wire connecting the two outer sides with each other
 rests against the rear side of the carrier element.
 For further improving the resistance to wear of the card clothings
 according to the invention, it has been found advantageous if, in a
 direction extending perpendicularly of the longitudinal axis of the card
 wire and approximately perpendicularly of the direction of the processing
 forces acting on the card wire during the processing of the raw material,
 the card wire has a width of at least 0.2 mm, preferably at least 0.4 mm,
 because it is possible in this manner that the pressure acting during the
 processing of the raw material through the card wires on the carrier
 element can be kept low without impairing the operation of the card, so
 that tearing of the carrier element in the area of the received sections
 of the card wires can be further counteracted.
 For ensuring a stability of the carrier element which is as high as
 possible, care must be taken that during the insertion of the card wires
 into the carrier element the material displacement within the carrier
 element is not too great. Therefore, for ensuring a high stability of the
 carrier element, the card wires preferably have a cross-sectional area
 which is as small as possible in a sectional plane extending
 perpendicularly of the longitudinal direction of the card wires. On the
 other hand, in view of the processing forces occurring during the
 processing of the fiber material, a sufficiently high stability of the
 card wires in the direction of the processing forces must be ensured. When
 using the above-described card wires having a width of at least 0.2 mm,
 preferably at least 0.4 mm, it has been found that a sufficiently high
 stability of the card wires in the direction of the processing forces can
 be ensured if the card wires have a width of less than 6 mm, preferably
 less than 5 mm, particularly preferred about 4.8 mm, while avoiding an
 excessive weakening of the carrier element by the material displacement
 occurring in the carrier element. It has been found particularly
 advantageous if the ratio of the thickness to the width is less than 3. In
 accordance with an especially preferred embodiment of the invention, the
 card wires have an essentially square cross-section in a sectional plane
 extending perpendicularly of the longitudinal axis of the card wire.
 In the known card clothings described above, an improvement of the
 engagement of the card wires with the fiber material is achieved if the
 processing section has at its end facing away from the carrier element a
 processing tip which is formed by two tip surface segments of the outer
 surface of the card wire extending at an acute angle of preferably less
 than 20.degree., particularly preferred about 16.degree., relative to each
 other, wherein at least one of the tip surface segments extends inclined
 relative to the longitudinal axis of the card wire and continues at a
 transition spaced in the direction of the longitudinal axis of the card
 wire from the processing tip in a rear outer surface segment of the outer
 surface of the card wire extending approximately parallel to the
 longitudinal axis of the card wire. Such processing tips are
 conventionally manufactured by grinding, embossing or punching card wires
 having a constant cross-section over the length thereof in a sectional
 plane extending perpendicularly of their longitudinal axes at one of their
 ends for preparing the tip surface segment extending inclined relative to
 the longitudinal axis. As a result, in the area of the transition between
 the tip surface segment manufactured in this manner and the rear outer
 surface segment extending parallel to the longitudinal axis of the card
 wire, usually so-called cutting beads are created to which the fibers to
 be parallelized can adhere. Therefore, conventional card wires must be
 subjected to a further grinding process for eliminating the cutting beads
 after manufacturing the processing tips. This correspondingly increases
 the costs for the manufacture of conventional card clothings.
 This cost increase can be avoided while simultaneously avoiding the
 accumulation of fibers in the area of the processing sections of the card
 wires of a card clothing according to the invention if the transition
 between the tip surface segment extending inclined relative to the
 longitudinal axis of the card wire and the rear outer surface segment of
 the card wire is arranged within the carrier element because the cutting
 beads produced during the manufacture of the tip surface segment are no
 longer located exposed outside of the carrier element when the textile
 fibers are processed and, therefore, fibers cannot adhere to the cutting
 beads.
 For achieving a particularly effective engagement of the card wires of a
 card clothing according to the invention into the fiber material, it has
 been found particularly advantageous if one of the tip surface segments
 extends approximately parallel to the longitudinal axis of the card wire
 and this tip surface segment includes an acute angle of approximately 5 to
 30.degree., preferably approximately 5 to 20.degree., especially preferred
 approximately 12.degree., with a surface normal contacting the processing
 tip on the front side of the carrier element.
 For ensuring a uniform processing or parallelizing of the individual fibers
 of the raw material, conventional card clothings have a receiving portion
 for receiving the received sections of the card wires, wherein the
 receiving portion has an essentially flat front side facing the processing
 sections. Such card clothings are conventionally fastened to a flat rod of
 the card by means of support clamps resting against the front side of the
 carrier element facing the processing sections. In this connection, the
 processing of the individual fibers of the raw material can be impaired by
 the support part of the support element resting against the front side of
 the carrier element. For eliminating this deficiency, it has been found
 advantageous if the receiving portion receiving the received sections of
 the card wires continues at at least one of its edges in a fastening
 portion whose front side facing the processing section is offset relative
 to the front side of the received section in the direction towards the
 rear side of the carrier element facing away from the processing sections.
 In this arrangement, the distance between the front side of the receiving
 portion and the front side of the fastening portion in a direction
 extending perpendicularly of the front side of the receiving portion is
 available for mounting the support clamp, wherein the support part of the
 support clamp resting against the front side of the fastening portion does
 not impair the processing of the textile fibers by means of the processing
 sections of the card wires protruding from the receiving portion of the
 carrier element.
 It has been found particularly advantageous with respect to manufacturing
 technology if the carrier element is constructed in the manner of a
 carrier web whose rear side facing away from the processing sections of
 the card wires is arranged in a plane extending approximately parallel to
 the front side of the processing portion, wherein the front side of the
 fastening portion can also be arranged in a plane extending approximately
 parallel to the front side of the processing portion.
 For ensuring a reliable and uniform processing or parallelizing of the
 individual fibers of the raw material, the card clothings according to the
 invention have a width extending over the entire width of the swift of a
 card, while the length thereof in a direction extending parallel to the
 predetermined processing path is substantially shorter than the width of
 the swift. Consequently, the front side of the processing portion of the
 carrier element facing the processing path of the swift usually is
 essentially rectangular. A reliable fastening of the card clothing to the
 flat rod can be ensured if the rectangular front side continues at at
 least one of its longer side edges, preferably at both of its longer side
 edges, in a fastening portion extending approximately parallel thereto.
 As already mentioned above, the card clothings according to the invention
 can be fastened to the flat rod of a card by means of a support element
 resting with a support part against the front side of the fastening
 portion of the carrier element and extending starting from the front side
 in the direction towards the rear side of the carrier element and possibly
 beyond, wherein a particularly reliable fastening is ensured if the
 support element has a fastening part penetrating the fastening portion of
 the carrier element.
 As can be gathered from the above explanation of the card clothings
 according to the invention, a carrier element suitable for manufacturing
 such card clothings is essentially characterized in that it includes a
 receiving portion serving for receiving the received sections of the card
 wires with an essentially flat front side which continues at at least one
 of its edges in a fastening portion whose front side is offset relative to
 the front side of the receiving portion in the direction towards the rear
 side of the carrier element. Such a carrier element is preferably
 manufactured of an elastic synthetic material, such as, for example,
 polyvinyl chloride, polyurethane or polyamide, possibly with appropriate
 softeners.
 For manufacturing card clothings according to the invention, it is
 advantageous to use carrier elements of synthetic material, particularly
 of PVC. In this connection, for increasing the strength, at least one
 fabric insert, preferably two fabric inserts which are spaced apart from
 each other in the thickness direction, are embedded in the carrier
 element.
 The various features of novelty which characterize the invention are
 pointed out with particularity in the claims annexed to and forming a part
 of the disclosure. For a better understanding of the invention, its
 operating advantages, specific objects attained by its use, reference
 should be had to the drawing and descriptive matter in which there are
 illustrated and described preferred embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The card clothing shown in the drawing essentially is composed of a carrier
 element 10 and a number of card wires 30 inserted into this carrier
 element 10. When viewing FIGS. 1 and 5 together, it is apparent that the
 carrier element 10 is formed in the manner of a carrier web with a width
 B, which essentially corresponds to the width of the swift of the card,
 and with a substantially shorter length K in a direction extending
 parallel to the direction of movement of the flats indicated by the arrow
 F in FIG. 5 along the predetermined path. It is apparent from FIG. 1 that
 the carrier element has a central receiving portion 12 with a
 comparatively great thickness into which the card wires 30 are inserted
 and which continues at its two opposite edges into a fastening portion 16
 each having a smaller thickness. For this purpose, the rear side 22 of the
 carrier element is essentially flat, while the front side 14 of the
 receiving portion 12 receiving the card wires 30 and having a greater
 thickness continues at both its opposite edges through steps 20 extending
 in the direction towards the rear side 22 into front sides 18 of the
 fastening portion 16 which is also essentially flat and extends
 approximately parallel to the rear side 22 of the carrier element 10.
 Consequently, the front sides 18 of the fastening portions 16 are offset
 parallel relative to the front side 14 of the receiving portion 12 in the
 direction towards the rear side 22 of the carrier element 10.
 The edge portions 16 of the carrier element 10 having a smaller thickness
 are available for mounting support clamps which are usually used for
 fastening the card clothing to a flat rod. The height difference d between
 the front side 14 of the receiving portion 12 and the front side 18 of
 each fastening portion 16 makes it possible that the support clamps can be
 mounted in a manner which does not influence the effectiveness of the
 processing sections 36 of the card wires 30 which are exposed and protrude
 above the front side 14 of the receiving portion.
 FIG. 2 shows an example of mounting support clamps 50 at the oppositely
 located fastening portions 16 of the carrier element 10. In the embodiment
 of the invention illustrated in this figure, the support clamp 50 has a
 support part 52 resting against the front side 18 of the fastening portion
 16, wherein, at its end facing away from the receiving portion 12 of the
 carrier element 10, the support part 52 has a clamp part 56 extending in
 the direction toward the rear side 22 and beyond and resting against a
 side surface 24 of the carrier element, and wherein, at its end facing the
 receiving portion 12, the support part 52 continues in a fastening part 54
 penetrating the carrier element 10. The end of the fastening part 54
 facing away from the support part 52 rests against the rear side 22 of the
 carrier element and ensures a reliable fastening of the support clamp 50
 at the carrier element. On the other hand, the end of the clamp part 56
 protruding beyond the rear side 22 of the carrier element 10 can be bent
 in a corresponding manner over a rear side of a flat rod in order to
 facilitate a reliable fastening of the card clothing to the flat rod. The
 thickness d' of the support part 52 in a direction extending
 perpendicularly of the front side 18 of the fastening portion 16 is
 smaller than the height difference d between the front side 14 of the
 receiving portion 12 and the front side 18 of the fastening portion 16. As
 a result, it is ensured that the effectiveness of the processing segments
 36 of the card wires 30 located exposed outside of the carrier element 10
 are not impaired by mounting the support clamp 50. As can be seen in FIG.
 5, the fastening portions 16 arranged at the opposite edges of the carrier
 element 10 extend approximately over the entire width B of the web-shaped
 carrier element. This facilitates a secure and reliable fastening of the
 card clothing to a flat rod over the entire width thereof.
 As illustrated particularly clearly in FIG. 3, the individual card wires 30
 inserted into the receiving portion 12 of the carrier element 10 are
 essentially U-shaped and have two outer sides 32 which are connected to
 each other through a connecting leg 48 resting against the rear side 22 of
 the carrier element. Each of the outer sides 32 has a received section 34
 received in the receiving portion 12 of the carrier element 10 and a
 processing section 36 which is exposed and protrudes by a distance L above
 the front side 14 of the receiving portion 12. The length L of the
 receiving portions 34 in the direction of the longitudinal axis 31 of the
 card wire 30 is substantially greater than the length l of the processing
 sections 36, wherein the length l is about 1 mm and the length L is about
 6 mm. As a result, an increased resistance to wear of the card clothing
 illustrated in the drawing is achieved, on the one hand, and a reduction
 of the quantity of short fibers accumulating in the area of the processing
 sections 36 is achieved, on the other hand. The width b of the individual
 card wires in a direction extending perpendicularly of the direction of
 movement F and parallel to the front side 14 of the receiving portion 12
 is in the card clothing illustrated in the drawing about 0.2 mm, while the
 thickness D of the card wire in a direction extending perpendicularly of
 the plane defined by the longitudinal axis 31 and the width direction is
 about 0.48 mm (see FIG. 4). As a result, while ensuring a sufficient
 stability of the card wire in a direction extending parallel to the
 direction of movement F, a force introduction of the processing forces
 acting on the processing sections 36 during a processing procedure into
 the carrier element 10 which is advantageous with respect to the
 resistance to wear of the card clothing according to the invention is
 ensured, on the one hand, and a material displacement when inserting the
 card wires 30 into the receiving portion 12 of the carrier element 10
 which is sufficiently small for guaranteeing a sufficient stability of the
 carrier element 10 is ensured, on the other hand.
 As illustrated particularly clearly in FIG. 4, the individual processing
 sections 36 of the card wires 30 have a processing tip 38 at their ends
 facing away from the front side 14 of the receiving portion 12. This
 processing tip 38 is formed by two tip surface segments 40 and 46 which
 include an acute angle .alpha. of about 16.degree. with each other. The
 tip surface segment 46 which is in the front in the direction of the
 movement of the flats indicated by the arrow F along the predetermined
 processing path during a processing procedure extends approximately
 parallel to the longitudinal axis 31 of the card wire 30 and includes an
 acute angle .beta. of about 12.degree. with a surface normal contacting
 the processing tip 38 onto the front side 14 of the receiving portion. The
 rear tip surface segment 40 located opposite the front tip surface segment
 46 includes with the longitudinal axis 31 of the card wire 30 the acute
 angle .alpha. and, at a transition 42 spaced apart in the direction of the
 longitudinal axis 31 of the card wire 30 from the processing tips 38,
 continuous in a rear outer surface segment 44 which extends parallel to
 the longitudinal axis 31 of the card wire 30. The transition 42 is
 arranged within the receiving portion 12 of the carrier element 10. As a
 result, it is ensured that the cutting beads produced during the
 manufacture of the rear tip surface segment 40 by a grinding, punching or
 embossing process in the area of the transition 42 are not exposed outside
 of the carrier element and, consequently, are also not available for
 holding individual fibers of the raw material to be processed with the
 card clothing according to the invention. Therefore, when manufacturing
 the card clothing according to the invention, an additional grinding
 process usually required for eliminating the cutting beads in the area of
 the transition 42 are unnecessary.
 As illustrated in FIG. 5, the connecting segments 48 of the card wires 30
 extend approximately parallel to the width direction of the carrier
 element 10, wherein the card wires inserted into the carrier element 10
 are combined into a plurality of processing strips which extend obliquely
 relative to the direction of movement indicated by the arrow F along the
 processing path and which extend parallel to each other. This ensures a
 uniform processing of the raw material over the entire width B of the card
 clothing.
 The invention is not limited to the embodiment explained in connection with
 the drawing. Rather, it is also conceivable to vary the angle between the
 front tip surface segment 46 and the surface normal onto the front side 14
 of the receiving portion 12 contacting the processing tip 38 within a
 range of between 5.degree. and 20.degree.. Moreover, instead of the card
 wires illustrated in the drawing with an essentially rectangular
 cross-section in a planar intersection extending perpendicularly of the
 longitudinal axis 31, it is also possible to use card wires with a square,
 round or oval cross-section. Furthermore, an embodiment is conceivable in
 which the front sides 18 of the fastening portions 16 extend starting from
 the side surfaces 24 in the direction toward the rear side 22 of the
 carrier element 10 in order to facilitate an even more reliable fastening
 of the support clamps 50.
 The invention is not limited by the embodiments described above which are
 presented as examples only but can be modified in various ways within the
 scope of protection defined by the appended patent claims.