Patent Application
20200255983
The invention relates to a flat clothing for a revolving flat of a carding machine, having a working width for processing fibers in a fiber running direction transverse to the working width, a foundation with a length that corresponds to the working width, and a width that is viewed in the fiber running direction. The flat clothing has a plurality of clothing tips that are formed from U-shaped small wire hooks that penetrate through the foundation and that are made of a wire having a cross-sectional width with two legs that form tips, and a back that has a back length and connects the two legs. The legs each have a tip axis. The small wire hooks are adjacently situated in rows with a distance between the oppositely situated tip axes, and the backs are situated with a back axis, connecting the tip axes, in the direction of the working width. A row offset in the direction of the working width, as the result of which small wire hooks in successive rows are not situated one behind the other, viewed in the fiber running direction, and a row spacing between two successive rows, are provided.
Various devices are known from the prior art that are used to separate dirt and short fibers in a carding machine. The problems that arise are described below, using cotton processing as an example. In cotton processing, after the cotton fibers are cleaned and opened to form fiber flocks in a carding machine, they are processed, cleaned, and parallelized. The fiber flocks are supplied via a feed chute to a licker-in, which transfers the fibers to the card cylinder. Over several revolutions of the card cylinder, the fibers are carded; i.e., the fibers are parallelized, oriented, and freed of dirt residues and trash particles. The function of the carding machine, among others, is to separate tiny knots (neps) and shell parts having fibers (seed coats), which can no longer be opened to form individual fibers in the subsequent processes. The shell parts and neps result in thick and thin locations in the yarn, which may lead to reduced quality of the yarn, and thus, a decrease in the sale price. In addition, the carding machine must remove dust, which is contained in the fiber material in the form of dust particles made up of rocks, sand, dirt, and tiny fibers. For this operation, so-called flats in the form of fixed or revolving flats are mounted opposite the card cylinder. Clothings which cooperate with the clothings present on the card cylinder are provided on the flats. This cooperation results in cleaning and longitudinal orientation of the fibers.
The relationships within a carding operation according to the prior art are now briefly explained, with reference to
The revolving flats basically fulfill four functions: opening the fiber flocks to form individual fibers, separating interfering particles, loosening fiber neps, and parallelizing and orienting the fibers. Since, as described above, separation of dirt particles does not take place until after individual fibers are picked up, a reduced pickup of individual fibers is also necessary for raw material with little soiling. In turn, the pickup of individual fibers depends on the position of the clothings relative to one another and the design of the flat clothing. In addition, the longitudinal orientation of the fibers is significantly influenced by the distance between the clothings of the card cylinder and the revolving flat, the so-called carding gap.
Numerous flat clothings that are used in revolving flats of carding machines are known from the prior art. For example, EP 0 041 076 A1 discloses an arrangement of clothing tips which, viewed in a fiber running direction, are slightly offset with respect to one another in such a way that a narrow passage for the fibers remains open. One disadvantage of such an arrangement is that, although a high carding effect can be achieved, a fiber jam results at the inlet of the flat due to the narrow passages. The teaching of EP 0 143 174 A2 recognizes this disadvantage, and attempts to address it by a progressive reduction in the spacing. One disadvantage of the proposed approach is that, although this gradual narrowing of the passage eliminated the known jams, it impaired the carding effect. In addition, CN 208 235 044 U, for example, discloses flat clothings having various types of arrangements of the small wire hooks, partially in differently spaced rows. However, the cited documents both state that the aim of the flat clothings is to parallelize the fibers, and at the same time, to separate trash particles and open up flocks. The requirements imposed on the flat clothing for optimal parallelization of the fibers are not compatible with the requirements for optimal separation of trash particles and the additional task of opening flocks. Therefore, the known flat clothings, which share the common feature of a uniform pattern in the arrangement, represent a compromise between at least two ideals.
WO 2018/104836 A1 attempts to eliminate this disadvantage by using different flat clothings in neighboring revolving flats. However, in the proposed approach it is disadvantageous that, according to the disclosure of WO 2018/104836 A1, the flat clothings result in a high degree of deflection of the fibers led past the clothings. Such a strong deflection results in damage to the fibers, so that the proportion of short fibers in the card sliver increases, or increased separation of short fibers must take place in the spinning preparation process for high-quality applications.
This carding procedure according to the prior art has the disadvantage that simultaneous cleaning and longitudinal orientation of the fibers represent a compromise for the requirements imposed on both processes. Due to the improvement in cleaning of cotton in the blowroom as well as the improved performance in the overall area of cotton processing in recent years, the demands on quality of the carding have continually increased. As a result of the use of currently available high-performance carding machines and the improvements in blowroom facilities, current processes accept excessive damage to fibers in relation to the dirt separation that is achieved, and the stress on the revolving flats and specifically on the individual clothing tips likewise increases. For example, a high dirt separation rate in revolving flats has the disadvantage that this must take place at the cost of equalizing the fiber direction; i.e., a large number of good fibers are picked up in the clothing and removed from the carding process, and therefore a lesser degree of parallelization of the individual fibers is accepted in order to achieve a high dirt separation rate.
An object of the invention is to provide a device that allows separation of dirt residues, trash particles, and neps, as well as a high volume of short fibers from a fiber material with simultaneous high equalization of the fiber direction, without resulting in damage to the fiber material or loss of good fibers. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
To achieve the objects, a novel flat clothing for a revolving flat of carding machine is proposed, having a working width for processing fibers in a fiber running direction transverse to the working width. The flat clothing has a foundation with a length that corresponds to the working width, and a width that is viewed in the fiber running direction, and a plurality of clothing tips. The clothing tips are formed from U-shaped small wire hooks that penetrate through the foundation and that are made of a wire having a cross-sectional width with two legs that form tips, and a back that has a back length and connects the two legs, the legs each having a tip axis. The cross-sectional width of the wire of the small wire hooks is measured transverse to the fiber running direction. Various wire cross sections are used in the prior art, the most common cross sections being listed in the DIN ISO 4105 standard (April 1984, card wires). For the various wire shapes, apart from the round wires, the cross-sectional height (h), which in the inserted state is situated in a flat clothing in the fiber running direction, is stated for biconvex, ovoid, sectoral, or flat wires, and the cross-sectional width (b) is also stated. Accordingly, the cross-sectional width (b) is situated transverse to the fiber running direction, corresponding to the direction of the working width, in the inserted state in a flat clothing. The biconvex wire, in which the tip axis extends in the geometric center of gravity of the wire cross section, is most commonly used nowadays.
The small wire hooks are adjacently situated in rows with a distance between the oppositely situated tip axes, and the backs are situated with a back axis, connecting the tip axes, in the direction of the working width, wherein a row offset in the direction of the working width, as the result of which the clothing tips in successive rows are not situated one behind the other, viewed in the fiber running direction, and a row spacing between two successive rows, are provided. At least two successive zones, viewed in the fiber running direction, are provided, wherein each zone has at least three rows, and the row offset of the first zone differs from the row offset of the second zone.
The different arrangement of the clothing tips in at least two zones allows a resolution of the compromise that has been made until now. The clothing tips are arranged differently in the two zones, so that it is possible to provide a flat clothing that is adapted to the requirements for parallelization as well as separation of dirt and short fibers. In addition, consideration is made for the fiber packet opening process, with good cleanability of the flat clothing via cleaning rollers. As a result of the row offset, i.e., the distance between two clothing tips in successive rows in the direction of the working width, being different, it is possible to provide a wider or narrower passage for the fibers in the fiber running direction.
Further, the row spacing between each row in the second zone and a following further row in the second zone, viewed in the fiber running direction, in each case is different from the row spacing between the row in the second zone and the preceding row in the second zone. As a result of the change in the row spacing from one row to the next, in combination with the small row offset, the number of clothing tips per unit distance in the fiber running direction is nonuniform, thus achieving increased parallelization. Due to the division of the flat clothing into different zones, with a more uniform density of clothing tips provided in a first zone, an overall nonuniform distribution of the clothing tips results over the working width, viewed in the fiber running direction. This results in the effect that the individual fibers on their way through the main carding zone are highly likely to pass by close to a clothing tip, so that parallelization of the fibers is achieved due to the friction.
In a first embodiment, the row offset of the first zone and the row offset of the second zone are greater than the cross-sectional width of the wire. In this first embodiment, the flat clothing is oriented toward high production output of the machine, using cotton, mixed wool with man-made fibers (MMF), or even just MMF, having little soiling. Due to the larger gaps between the clothing tips, large pieces of foreign matter are still picked up, and simple cleaning is achieved with a good separation and parallelization effect. In relation to a certain working width, the clothing tips are far apart, so that a passage that is larger in comparison to a fiber diameter results between the individual clothing tips. Thus, only a portion of the fibers to be processed come into contact with a clothing tip, resulting in only a portion of the fibers in the fiber material having the same direction. However, individual fibers are captured by the clothing tips and utilized for dirt separation. In the second zone, the row offset is changed with respect to the first zone, as the result of which a passage width between the individual clothing tips, viewed in the fiber running direction, is at least different in the second zone compared to the first zone, which, viewed across both zones in the fiber running direction, results in a shift of the passages, and thus, parallelization of the fibers.
In a second embodiment, the row offset of the first zone and the row offset of the second zone are less than or equal to the cross-sectional width of the wire. In this second alternative embodiment, the flat clothing, in contrast to the first embodiment, tends to be more strongly oriented toward the parallelization of fibers. In relation to a certain working width, the clothing tips are close to one another, so that a passage that is small in comparison to a fiber diameter results between the individual clothing tips. Thus, a greater portion of the fibers to be processed come into contact with one of the clothing tips, resulting in a large portion of the fibers contained in the fiber material having the same direction on account of the more closely spaced clothing tips.
In another embodiment, the row offset of the first zone is greater than the cross-sectional width of the wire, and the row offset of the second zone is less than or equal to the cross-sectional width of the wire. The arrangement of the clothing tips in the first zone is identical to the arrangement according to the first embodiment. However, in the second zone the row offset is smaller in comparison to the cross-sectional width of the wire that is used. This intensifies cleaning and parallelization of the fibers in the fiber running direction due to a narrowing of the passages between the clothing tips. Staggered dirt separation with maximum carding performance and optimum cleanability of the flat clothing are achieved. In addition, the fiber flocks may be better opened up in the first zone, and the coarse dirt particles may be better extracted in the first zone during cleaning of the flat clothing with a cleaning roller, since the distances are greater, and therefore there is more room for penetrating cleaning bristles of the cleaning roller down to the base of the flat clothing. The improved cleaning characteristic results in consistent performance over the service life of the revolving flat.
In the first zone, the row offset of each row with respect to a following row is preferably the same. It is also advantageous when in the second zone, the row offset of each row with respect to a following row is preferably the same. The flat clothing is thus separated into two zones in the fiber running direction, with no smooth transition resulting between the zones.
The row spacing between each row in the second zone and a following further row in the second zone, viewed in the fiber running direction, in each case is preferably smaller than the row spacing between the row in the second zone and the preceding row in the second zone. Due to the reduction in the row spacing, the number of clothing tips per unit distance in the fiber running direction increases, resulting in increased processing of the fibers. The division of the flat clothing into different zones, with a lower density of clothing tips provided in a first zone, results in a reduction in the good fibers picked up by the flat clothings for dirt separation. This also results in the effect that the individual fibers on their way through the main carding zone do not clog as quickly, which also results in better efficiency. The effect of the flat clothing is maintained over a fairly long distance along the card cylinder surface.
An extension of the first zone in the fiber running direction is advantageously 30% to 70% of an extension of the second zone. It has been shown to be advantageous for the second zone to have at least seven rows. With a smaller number of rows, a division into subgroups within the second zones is not possible. It has also been shown that the effect of the rows may be intensified by increasing the number of rows in the second zone.
In the second zone, two to four rows arranged in succession in each case advantageously form a subgroup, and the row spacing between successive rows within a subgroup, viewed in the fiber running direction, respectively increases or decreases, wherein a subgroup with increasing row spacing is followed in each case by a subgroup with decreasing row spacing, or a subgroup with decreasing row spacing is followed in each case by a subgroup with increasing row spacing. This wave-like arrangement configuration of the clothing tips results in further improvement in the effects described above.
An advantage in manufacturing results when, as an alternative to forming subgroups in the second zone, two to four rows arranged in succession in each case form a group of rows, the row spacing within a group of rows being the same.
In current applications of the flat clothing, it has been shown that optimal carding may be achieved when the flat clothings for revolving flats have 30 to 48 rows, 3 to 45 rows of which belong to the first zone. For process engineering reasons, the number of rows introduced into the flat clothing is limited due to the width of customary flat clothings.
The distance of a tip axis of a first small wire hook from the oppositely situated tip axis of a subsequent small wire hook in the same row is preferably the same as the length of the backs of the small wire hooks. This results in a uniform setting pattern of the clothing tips. From a manufacturing standpoint, it is advantageous for the small wire hooks to have a back length of less than 3.5 mm between the tip axes.
Also within the scope of the invention is a revolving flat for a carding machine, having a flat clothing according to one of the described embodiments.
The invention is explained in greater detail below based on exemplary embodiments and with reference to the drawings, which show the following:
Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.
The small wire hooks 28 are formed from a wire having a cross-sectional width b. The U-shaped small wire hooks 28 have two legs 29 and a back 30 that connects the legs 29. The two legs 29 are each formed into a clothing tip 23 at their ends situated opposite from the back 30. The clothing tips 23 are generally formed by a grinding process after the small wire hooks 28 are inserted into the foundation 27. The legs 29 have a tip axis 31, and the backs 30 have a back axis 32. A back length E is provided as the distance between the tip axes 31 of a small wire hook 28 in the direction of the back axis 32.
Multiple rows 36 and 37 that follow one another in the fiber running direction C are situated in a first zone 34 having an extension M. The rows 36 and 37 have a row spacing L1. The small wire hooks 28 adjacently situated in the rows 36, 37 show a row offset K1, wherein the row offset K1 indicates the shift of the clothing tips that are formed by the small wire hooks 28. This is illustrated by the indication of the row offset K1 between the row 37 and the row that follows in the fiber running direction C.
Multiple rows 38, 39, 40 that follow one another in the fiber running direction C are situated in a second zone 35 having an extension N. The rows 38 and 39 as well as the rows 39 and 40 have a row spacing L2. The small wire hooks 28 adjacently situated in the rows 38, 39, 40 show a row offset K2, wherein the row offset K2 likewise indicates the shift of the clothing tips that are formed by the small wire hooks 28. The row offset K2 in the second zone N differs from the row offset K1 in the first zone M. In addition, in the exemplary embodiment shown, the row spacing L2 between successive rows 38, 39, 40 in the fiber running direction C decreases as viewed in the fiber running direction C.
Multiple rows 36 and 37 that follow one another in the fiber running direction C are situated in a first zone 34 having an extension M. The rows 36 and 37 have a row spacing L1. The small wire hooks 28 adjacently situated in the rows 36, 37 show a row offset K1, wherein the row offset K1 indicates the shift of the clothing tips that are formed by the small wire hooks 28. This is illustrated by the indication of the row offset K1 between the row 37 and the row that follows in the fiber running direction C.
Multiple rows 38, 39, 40 that follow one another in the fiber running direction C are situated in a second zone 35 having an extension N, the rows 38, 39, and 40 forming a subgroup 42. The rows 38 and 39 have a row spacing L2, and the rows 39 and 40 have a row spacing L3. The subsequent three rows form a second subgroup 43, wherein the row spacing L2 or L3, viewed in the fiber running direction C, in the second subgroup 43 is opposite the row spacing pattern in the first subgroup 42. As a result, a subgroup 43 having an increasing row spacing L2, L3 within the subgroup 43 follows a preceding subgroup 42 having a decreasing row spacing L2, L3. This pattern of the row spacings is in turn reversed in the subsequent subgroup. The small wire hooks 28 adjacently situated in the rows 38, 39, 40 show a row offset K2, wherein the row offset K2 likewise indicates the shift of the clothing tips that are formed by the small wire hooks 28. The row offset K2 in the second zone N differs from the row offset K1 in the first zone M.
The present invention is not limited to the exemplary embodiments that are illustrated and described. Modifications within the scope of the patent claims are also possible, as well as a combination of the features, even if these are illustrated and described in different exemplary embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 00155/19 | Feb 2019 | CH | national |
