Patent Application
20130042437
The present invention concerns a wire profile for card clothing comprising a rib portion and plurality of teeth over the length of said rib portion.
Carding is one of the fundamental operations in manufacturing of yarn and in the production of carded nonwoven products. Carding is a process that transforms the raw material, such as cotton, wool or polyester fibres, into a coherent web by disentangling and straightening the fibres and eliminating undesired materials. At the output side of the card, the web is combined into a so-called “sliver”, a one dimensional ribbon of fibres; or transferred as a web to the next process. The control of fibres during the carding process is carried out through metallic and/or flexible card clothing and by control of the air flows. Although the basic principles underlying the carding process have not changed for over 100 years, there has been a constant improvement in the manufacturing technology thus resulting in an improved speed and efficiency.
U.S. Pat. Nos. 4,233,711, 4,964,195, 464,389, 5,755,012 and 6,408,487 relate to different metallic card clothing. WO00/26450 describes card clothing comprising a strip of profile wire having a plurality of longitudinally aligned teeth with respective overhanging tips. The edge-face of each tooth under the overhanging tip includes at least one undercut edge-segment spaced along the edge-face from the tip. This undercut edge-segment increases the retention of fibres by the edge-face during carding by means of a preferably substantially horizontal step in the undercut. WO00/26450 describes that for performance and lifetime related reasons, the undercut edge segments can be optimized by careful design, this statement, however, leaves the drawback unsolved that the wires cannot be made via state of the art rotary punching technology.
The prior art fails to address a desirable card clothing that has the following characteristics (i) a perfect control of the fibre, this is an extremely critical step during carding because the card clothing must not only be capable of penetrating into the fibre material, but also retain the fibre without resulting in damage to the fibres; (ii) desirable card clothing should be able to transfer the fibre between rollers clothed with wires, e.g. from the main cylinder to the removal cylinder known as doffer. An issue noted with the wire profile known in the art is that strong fibre taking capacity leads to fibre loading at the stop-start of the cards. It should be noted that the type of fibre also plays a major part in transfer for instance the card profile being used for woven or non-woven units. (iii) desirable card clothing should minimize the various macroscopic deformations to the fibres such as transverse compression, stretching and twisting; (iv) Certain wire profiles known in the art such as in WO 00/26450 cannot be produced by rotary punching technique and it is thus desirable that the card clothing be mass producible using rotary punching technique for specific geometries and; (v) must be wear resistant so that replacements of card clothing on the rollers and plates of the carding machines are less common thus saving time and maintenance costs. The wire profile known in the art have problems with decreased tooth strength due to stress concentration at the edges thus occurrence of breakage of part of tooth is common and the fibre retention capacity is lost.
In order to obtain desirable card clothing, major amount of research has been focussed on the geometry of the card clothing, these hook shaped card clothing act directly on the fibres to break down and tease the tufts into individual fibres; and to orient the fibres.
To manufacture card clothing, wire forms the basic starting material which is subjected to one or more drawing and rolling operations followed by punching a series of consecutive slots to form the teeth using a suitable mechanical stamping device as described in GB 2 257 164 A.
GB 2 257 164 A elaborates on two punching techniques, vertical and rotary, both these techniques are known for producing teeth in a blade. The vertical punching technique involves a vertically reciprocating cutter tool passing in and out of a shaped die over which the blade is temporarily held. Thus, in accordance with this known technique, the blade must be moved intermittently and periodically held stationary in order to perform the punching operation. One of the disadvantages with this technique is that it is a very slow process to manufacture saw toothed wire and it drastically impacts the efficiency of manufacturing rollers or replacing rollers, cylinders, doffers with saw toothed wires because the low volume output. The rotary punching technique on the other hand involves the use of a rotating cutting tool which is set to pass through a shaped die, over which the blade passes continuously. The advantage of this technique is the high speed and ability to manufacture saw toothed wires in kilometres of stretch in short span of time. U.S. Pat. No. 6,195,843 describes one rotating cutting tool which has a rotary milling spindle with a blanking tool attached to it, the angular position of the milling spindle can be continuously registered by means of an angular decoder, and the feed mechanism can be controlled on the basis of the angular position that has been determined in this manner. There is however a disadvantage with the rotary punching technique which is the limitation to manufacture any geometry and shapes of saw toothed wire. Furthermore GB 2 439 638 mentions the disadvantages of manufacturing card clothing using mechanical tool means (referring to vertical and rotary punching) and in particular mentions the problems of oxide residues during thermal treatment, production accuracy deteriorates with wear and tear on the tool and suggests to use laser for producing card clothing. Precision may be better since the laser beam doesn't wear during the process. A disadvantage of laser cutting is the high energy required. With part geometries, lasers also face the problem with a part absorbing more heat, and consequently the probability of thermal runaways or violent reactions like blowouts increases.
It is an object of the present invention to provide for a wire profile for card clothing which overcomes the drawbacks of known carding wires by a specific well-defined geometry of the teeth of wire profile for card clothing which can be easily and consistently produced using the rotary punching technique.
It is another object of the present invention to provide for a wire profile which efficiently penetrates, captures and controls the synthetic and natural fibres during the carding process.
It is another object of the present invention to provide for a wire profile to create fibre space so that increased volume of fibres can be retained in the card wire. Using the present invention on a doffer of a card, fibre recycling on the cylinder is reduced.
It is another object of the present invention to provide for a wire profile which imparts frictional resistance to the fibre during the carding process.
Thus, one aspect of the invention is a wire profile for card clothing comprising a rib portion and plurality of teeth over the length of said rib portion, wherein said teeth are sloped with a back slope representing the backbone of said teeth and a front slope representing the side in direct contact with fibre, said back slope having a tangent forming a back angle with the rib portion, said front slope being divided into at least two segments, a tip segment and a undercut segment, wherein said tip segment converges with the said back slope to form a tip of said teeth and said tip segment serves to penetrate between fibres, said tip segment having a tangent forming a tip angle with the rib portion, said undercut segment is capable of retaining the fibre, said undercut having a tangent forming an undercut angle with the rib portion, said undercut angle being at each point in the undercut segment greater than the maximum of the back angle and being smaller than the smallest value of the tip angle. In another aspect of the present invention, the wire profile further comprises a base segment originating below the said undercut segment and said base segment converges towards the said rib portion, and wherein said base segment having a tangent forming a base angle with the rib portion and maximum of said base angle is greater than the said undercut angle.
The wire profile of the present invention allows the possibility to be manufactured by rotary punching technique.
Thus, another aspect of the invention is a method of manufacturing wire profile of the present invention by a process comprising the steps of: (i) feeding wire by means of continuous feeding mechanism; and (ii) performing a slicing procedure using a rotary blade, wherein said rotary blade is set to pass through a shaped die.
Difference between α and β ranges from 0.1-20°, preferably 0.5-10°, more preferably 0.5°-5°. In one preferred embodiment of the present invention, the angle α is 39°, the angle β equals 35°, the angle λ is 57° and the angle μ is 52°.
In one preferred embodiment of the present invention, the wire profile for card clothing comprises a rib portion and plurality of teeth over the length of said rib portion, wherein said teeth are sloped with back slope representing the backbone of said teeth and front slope representing the side in direct contact with fibre, said back slope having a tangent forming a back angle with the rib portion, said front slope being divided into three segments, a tip segment, a undercut segment and a base segment, wherein said tip segment converges with the said back slope to form a tip of said teeth and said tip segment serves to penetrate between fibres, said tip segment having a tangent forming a tip angle with the rib portion, said undercut segment is capable of retaining the fibres, said undercut having a tangent forming an undercut angle with the rib portion, said undercut angle being at each point in the undercut segment greater than the maximum of the back angle and being smaller than the smallest value of the tip angle and, wherein said front slope comprises a further base segment originating below the said undercut segment and said base segment converges towards the said rib portion, and wherein said base segment having a tangent forming a base angle with the rib portion and maximum of said base angle is greater than the said undercut angle, in order to allow rotary punching.
In one preferred embodiment of the present invention, the said base angle λ is smaller than the smallest value of the tip angle μ.
In one preferred embodiment of the present invention, the said tip angle ranges between 40° and 135°, preferably between 45° and 90°, more preferably between 45° and 70°, most preferably between 50° and 65°.
In one preferred embodiment of the present invention, the said back angle ranges between 10° and 80° preferably between 20° and 50°, more preferably between 30° and 45°.
The term “striations” 124, 224 refers to a number of tiny parallel grooves/veins along the longitudinal direction of the wire profile. Such a profile is preferably manufactured in the undercut segment of the teeth wherein the fibres are retained. In one embodiment of the present invention the teeth of the wire profile comprises striations along the longitudinal direction of the said wire profile. In another embodiment of the present invention the striations are positioned along the said undercut segment. In yet another embodiment of the present invention the striations are in form of grooves and veins occurring in alternative forms along the either side of the wire profile to increase fibre retention capabilities.
The term “spaced segment” refers to the spacing between a pair of teeth and in particular the segment refers to the base portion of said teeth wherein the front slope of one teeth and back slope of adjacent teeth converges towards the rib portion.
The term “carding machine” refers to machine consisting out of rotating cylinders clothed with card wire and (if present) quasi-stationary or stationary flat plates. For instance the term “carding machine” refers to workers, doffers, strippers, condensers, transfer rollers may be even on lickerin or cylinders (nonwoven/long staple carding); and for short staple for the doffer wire and possibly also for metallic tops. The carding machine comprises the wire profile of the present invention. In one embodiment of the present invention the carding machine is a doffer for short staple.
In another embodiment of the present invention the carding machine is a worker on a roller card for nonwovens or long staple carding.
In another embodiment of the present invention the carding machine is a doffer on a roller card for nonwovens or long staple carding.
In another embodiment of the present invention the carding machine is a transfer roller on a roller card for nonwovens or long staple carding.
In another embodiment of the present invention the carding machine is a stripper on a roller card for nonwovens or long staple carding.
A wire profile of the present invention can be made as follows. Starting product is a wire rod (usual diameters 1.20 mm or 7.0 mm) with a steel composition along the following lines: carbon content ranging from 0.30% to 2.0%, e.g. from 0.5 to 1.2%; e.g. from 0.6 to 1.1%; silicon content ranging from 0.10% to 2.5%, e.g. from 0.15 to 1.60%; manganese content ranging from 0.10% to 2.0%, e.g. from 0.50 to 0.90%; chromium content ranging from 0.0% to 2.0%, e.g. from 0.10% to 1.50%; e.g. from 0.10% to 0.90%; vanadium content ranging from 0.0% to 2.0%, e.g. from 0.05% to 0.60%, e.g. from 0.10% to 0.50%; tungsten content ranging from 0.0% to 1.5%, e.g. from 0.1% to 0.70%.
In one embodiment of the present invention, the composition of wire profile may contain either chromium or vanadium. In some other compositions both chromium and vanadium are present. The amounts of sulfur and phosphorous are preferably kept as low as possible, e.g. both below 0.05%, e.g. below 0.025%.
The wire rod is cold and dry drawn until the desired non-round profile is reached. Rolling can be carried out by means of Turks heads or by means of rolls. Drawing can be done by means of profile drawing dies. The profile depends upon the application can be square, rectangular, or take an L-form. The basis leg of the L forms the rib portion and the top leg of the L will house the eventual teeth. After this profiling, the teeth are formed in the profile wire by means of a cutting operation preferably a punching operation. The forming of the teeth may be followed by a deburring operation.
Thereafter the formed saw toothed wire profile is subjected to some heat treatments, which aim at stress-relieving the rib portion of the saw-toothed wire and at hardening the teeth. Therefore, the entire saw toothed wire is heated until a temperature in the neighborhood of 600° C. and the teeth get an additional heating until they reach a temperature of about 900° C. Thereafter the entire wire is quenched so that the foot is stress relieved and the teeth are hardened since the teeth are subjected to a much greater jump in temperature. The global heating until 600° C. can be done by means of induction heating or by means of a gas burner. The heating of the teeth until 900° C. can be done by means of an additional gas burner, or by passing the teeth through a plasma arc or torch. The quenching operation can be done in an oil bath or in a bath of polymers.
The performance of the card wire can be verified via the visual observation of the web regularity and of the number of neps present in the web. In the case that slivers or slubbing is formed at the exit of the card (that will be further processed in short staple or long staple yarn spinning), the sliver or slubbing can be tested on the number of neps and the distribution of the fibre length. In the case of cotton slivers, the AFIS (Uster's Advanced Fibre Information System) test device is a well known device used for testing sliver parameters such as number of neps, trash particles and fibre length and fibre length distribution. In the case of spun yarns, the yarn can be tested on a regularity tester and the number of neps, number of thin places and the number of thick places can be determined to assess quality of the yarn.
Using card wires according to the present invention on doffer rollers or on worker rollers more fibres will be present on these rollers than when using conventional wires. When taking a piece of card wire according to the present invention, putting fibres on the teeth and keeping the wire piece with the teeth down, more fibres are held on the teeth, less fibres drop compared to the same experiments with conventional wires.
Any reference signs do not limit the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10161813.0 | May 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/057047 | 5/3/2011 | WO | 00 | 11/1/2012 |
