Cored yarn, and method and apparatus for producing the same

Abstract: Rovings 30A and 30B as drafted are, under a parallel condition, passed through a collector 16, twisted and wounded from front rollers 12-1 and 12-2. A core yarn 34 is, via a guide member 40 as a snail wire, introduced into rovings 30A and 30B from the rear side of the front rollers. Since the guide member 40 is fixedly connected to the collector 16, the guide member 40 can follow with the lateral displacement of the collector 16, so that a central feed of the core yarn 34 to the rovings 30A and 30B is maintained, thereby always keeping a condition that the core 34 is fully covered by the outer fibers.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cored yarn having, as inner fibers (core), stretchable filament yarns such as spandex (polyurethane elastic yarns) and, also, relates to a method and apparatus for producing such a cored yarn. 2. Description of Related Art Various types of cored yarns, having, as a core, stretchable filament yarns such as spandex and having, as an outer part, natural fibers such as wool or cotton (staple fibers), have here-to-fore been proposed. Such a type of core yarn is intended for imparting to the yarn a stretchability of the spandex as well as a soft touch of the natural fibers and is targeted to be used for a knit wear. In order to produce such cored yarn, a fine spinning of wool or cotton is carried out in such a manner that the core is mixed with a roving from a rear side of front rollers. The stretchable filaments mixed with the roving under drafting operation from the front rollers is subjected to a twisting operation together with the drafted outer fibers constructed by wool or cotton and is subjected to a winding operation, resulting in a formation of a cop. In the conventional cored yarn have, as a core, spandex, a use of wool as outer fibers may case a soft touch to be easily lost due to a shrinkage as occurred by a washing. Thus, a selling of the product must necessarily be made together with a warning for prohibition of a washing, which may likely cause the products not to be accepted in the market. Furthermore, in the prior art cored yarn, a condition, that a core (inner fibers) is completely covered by the outer fibers, is not always maintained. Namely, any control of the core is not done, resulting in an exposure of the core yarn to the outer layer at positions along the length of the yarn. In such a situation, the yarns provide locally differently sparkled portions, which makes a knitted fabric to be defective one and which also makes a dyed fabric to be defective one since the sparkled portions are colored differently. LU-A-48 578 describes an arrangement in which outer fibers are supplied to a drafting part of a fine spinning frame and filament fibers are supplied to front rollers of the drafting part so that the filament fibers are combined with the outer fibers. The filament fibers are fed through a fixed guide whilst the outer fibers can undergo lateral movement such that the filament fibers may not be located centrally between the outer fibers. SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned difficulties. According to a first aspect of the present invention there is provided a method for producing a cored yarn having filament fibers as a core which is covered by outer fibers, wherein rovings as the outer fibers are supplied to a drafting part of a fine spinning frame, while the filament fibers are supplied via a guide member to front rollers of the drafting part in such a manner that the filament fibers are combined with the rovings via a collector which is subjected to a reciprocating movement parallel to the front rollers characterised in that the supply of the rovings to the drafting part is such that a plurality of such rovings are fed under a parallel relationship, so that these rovings are substantially separately twisted when issuing from the drafting part, while a movement parallel to the front rollers is mechanically integrated between the guide member for the filament fibers as the core and the collector for the rovings whereby the filament fibers as the core are located intermediate between said separately twisted rovings constructing said outer fibers which are finally twisted about each other to form a cored yam. In the operation of the method, a plurality of rovings are fed, in parallel, to the draft part, and a guiding of the filament fibers as the core is done in such a manner that the filament fibers are always fed to the central position between the rovings which are fed in parallel. As a result, an advantage is obtained that a condition is always and steadily obtained that the filament fibers as the core is fully covered at the center of the outer fibers. As a result, the filament fibers as the core is prevented from being displaced to the outer layer and, in a subsequent process, an occurrence of defects at a knitting or weaving or dyeing speck is substantially completely prevented. According to a second aspect of the invention, a system is provided for producing a cored yarn, wherein it comprises a drafting part for executing a drafting operation of rovings as outer fibers, a collector arranged at an inlet of front rollers of the drafting part for collecting and guiding the rovings toward the front rollers, feeding means for feeding filament fibers from the front rollers of the drafting part so that the filament fibers are combined with the rovings subjected to the drafting operation, and means for twisting and winding fibers from the front rollers, characterized in that said collector has a groove of a width which allows the plurality of rovings to be fed to the front roller while keeping said parallel condition and that a guide member is mounted to the collector for guiding the filament fibers from the feeding means so that the filament fibers are fed to the front rollers at an intermediate position between the rovings. In the operation of the system, a plurality of rovings during the drafting is maintained in their paralleled condition at the collector and are twisted and taken up from the front rollers. The guide member for guiding the filament fibers is mounted to the collector. As a result, even in a movement (displacement in the direction parallel to the front rollers of the collector, the guide member is always integrally moved with respect to the collector, so that a positional relationship of the filament fibers between intermediate between the rovings is always maintained. As a result, a condition is constantly and steadily obtained that the filament yams as the core are completely and centrally covered by the outer layer fibers. In the fifth invention, a very simplified construction, that the guide member is fixedly connected to the collector, can solve the problem and, therefore, is advantage since the aim can be realized at a reduced cost. BRIEF DESCRIPTION OF ATTACHED DRAWINGS Fig. 1 is a schematic view illustrating a side view of a device for fine spinning according to an embodiment of the present invention. Fig. 2 is a schematic view illustrating a plan view of the device for fine spinning. Fig. 3 is a schematic perspective view of a fine spinning frame viewed from the rear side of front rollers in a drafting part. Fig. 4 is a schematic perspective view of a fine spinning frame viewed from the front side of the front rollers in the drafting part. Fig. 5A is a schematic cross sectional view of a cored yarn. Fig. 5B is a schematic cross sectional view of a cored yarn in the prior art. Fig. 6 is a view illustrating an outer appearance of the cored yam produced in accordance with the present invention. Fig. 7 schematicallv illustrates a construction of the core used in the cored yarn produced in accordance with the present invention. DETAILED EXPLANATION OF PREFERRED EMBODIMENT Now, an embodiment of the present invention will be explained, wherein, in a cored yarn a core (inner fibers) can be a spandex (polyurethane elastic yam) subjected to a heat setting, and outer fibers can be wool fibers such as merino wool, cashmere, camel, alpaca or angora. Preferably, the spandex is of a type which is subjected to a heat set treatment for reducing a stretchability. The heat set treatment is desirably of a so-called high heat set type, where a heat treatment in a liquid is done in a temperature range of 100 to 130 °C for a duration of 60 minutes, so that a value of a set ratio in a range between 60 to 80 % is obtained, resulting in an increased dimensional stability as to fabric width as well fabric density as obtained after execution of a knitting operation. In this specification, the set ratio implies a ratio, to a the sample length of a spandex yarn, of an elongation under a relaxed condition after a heat treatment for a predetermined time under 100 % stretching of the yam (twice length stretching of the sample). A value of set ratio of 50 %, for example, implies that, when by an elongation of a spandex yam of a length of 10 cm to a length 20 cm of under a loading under a heat treated condition for a predetermined time, a sample length is 15 cm after the loading is cancelled. As for the spandex, the one is desirable, that has an outer layer which is constructed by lapped nylon filaments. The nylon has an increased dyeability, which causes an occurrence in the dying defects to be less likely, resulting in an increased acceptability in the market of a fabric which is obtained by knitting the core yarn. As for the wool fibers, the ones subjected to the non-shrink treatment is desirable. As well known, in such a non-shrinkage treatment, the wool is subjected to an alkaline treatment for removing scales. In accordance with production sites of wool, conditions for the non-shrink treatment are respectively determined. Non-shrink treatment wool from the various production sites can be used. The use of the wool as the outer layers allows a soft touch to be obtained and the non-shrink treatment of the wool allows the washability to be enhanced and the soft touch to be, advantageously, maintained. As for the outer fibers, in place of the wool as explained above, synthetic cut fibers (staple fibers) such as acrylic, rayon, nylon, polyester or acetate fibers can be used and natural fibers such as jute (linen, ramie or hemp) or cotton or silk can be used. The cored yarn is constructed by inner fibers constructed by the stretchable filament yarns, preferably high set type spandex and outer fibers constructed by short fibers, preferably non-shrink treated wool and the stretchable filament yarns are twisted centrally between the rovings as the outer fibers fed separately. In this case, during the manufacture of the cored yarn, the short fibers (staple fibers) as the outer fibers are constructed by two rovings which are simultaneously fed to the drafting part, where the rovings are subjected to the drafting operation. The two rovings from the front rollers are, first, twisted separately and, finally, formed to a single yarn, which is wound to a shape of a cop shape. In this case, the rovings coming out from the front rollers, which although are located very close with each other, subjected to a twisting operation under individually separated condition, which causes the fibers to be mutually engaged, thereby obtaining a taken-up yarn of a reduced fuzz as well as of an increased smoothness. Furthermore, the guiding operation of the stretchable filament yarns as the core from the rear side of the front rollers is such that the stretchable filament yarns are always fed to the two rovings at the central position. In order to cause the stretchable filaments to be guided, a guide of the shape of the so-called snail wire are fixedly connected to the collector. As a result, the feed of the stretchable filaments as the core are always done at the position intermediate between two drafted rovings. As a result, at the outlet of the front rollers, the stretchable filaments (core) are, at location where the separately twisted rovings are combined, twisted between the parts constructed by the separately twisted rovings. As a result, the core is always located centrally of the short fibers (staple fibers) as the outer fibers. In other words, the core can always maintain a condition that it is fully covered by the outer fibers, which prevents the core fibers from being emerged to the outer layer, which otherwise causes a defect to be generated at a knitting process, since the outwardly emerged core fibers are sparkled differently and which otherwise causes a defect to be generated at a dying process since the outwardly emerged core fibers are dyed differently from the wool fibers. Advantageously, the core is a spandex, about which synthetic fibers of an increased dyeability such as nylon are rapped, which makes an occurrence of an defect to be less likely during the execution of the dying process. Now, a construction of a worsted fine spinning frame which is used for an execution of the present invention will be explained. In Fig. 1, the fine spinning frame includes a drafting part which is provided with a back roller pair 10, a front roller pair 12, and an apron pair 14. The back roller pair 10 is constructed by a bottom roller 10-1 and a top roller 10-2, the front roller pair 12 is constructed by a bottom roller 12-1 and a top roller 12-2, and the apron pair 14 is constructed by a bottom apron 14-1 and a top apron 14-2. Arranged adjacent to the front bottom roller 12-1 is a collector 16, which collector 16 is adapted to function with a guide for directing the roving under the drafting operation toward the front roller pair 12. In a well known manner, the collector 16 is mounted to a wire shaped holder 18 (see Fig. 3) which is extended toward the front roller pair 12 from an end of a cradle (not shown) which functions as a supporting frame of the bottom apron 14-1. The ratio (draft ratio) of rotational speed of the front roller pair 12 with respect to the rotational speed of the back roller pair 10 is a predetermined value, which causes a drafting to be imparted to the roving directed to the front roller pair 12, which causes the roving to be thinner, which is issued from the front roller pair 12 and is, via the snail wire 20 and the traveler 22, wound to the paper tube 22 on the spindle while being subjected to the twisting, thereby obtaining a shape of the cop 26. A not shown creel is provided, on which bobbins are provided. As shown in Fig. 2, for each of the spindles, two roving bobbins 28A and 28B are provided. The rovings 30A and 30B twisted slightly and taken out of the bobbins 28A and 28B at each spindle are fed, under a parallel condition, to the drafting apparatus. As a result, between the back roller pair 10 and the front roller pair 12, the rovings, which are kept in parallel, are subjected to a drafting operation under a predetermined drafting ratio. During the drafting operation, the rovings 30A and 30B are nipped vertically by the apron pair 14, which allows floating fibers to be controlled, thereby obtaining an even drafting operation. As a result, the rovings 30A and 30B are basically maintained under a parallel condition on the guiding groove 16-1 of the collector (Fig. 3) and are fed to the front roller pair 12. In other words, the collector 16 (Fig. 3) must necessarily be provided with a width which is large enough to cause the rovings 30A and 30B to be fed in parallel under separated condition. The rovings 30A and 30B issued from the front roller pair 12 are, first, subjected to a separate twisting due to the rotating movement of the spindle, are, then, gradually converged and are, finally, composed to a single yam. Such a system, wherein, for each spindle, two rovings are fed under a parallel condition, which are, after execution of drafting followed by twisting, combined to a single yarn, is based on the patent owned by the commonwealth Scientific Industrial Research Organization (CSIRO) in Australia and is called as a CSIROSPUN. This system is advantageous over a conventional system where a single yarn is subjected to a drafting in that, under the same yarn count as well as a twisting number, an increased anti-abrading performance as well as a reduced occurrence of fluff are obtained. The CSIROSPUN system is improved in that the introduction of the synthetic stretchable filament yarns (polyurethane elastic fibers (so-called spandex yarn)) as the core is done at the center between the rovings 30A and 30B which are in parallel condition and a control of the feed of the core is done in such a manner that the feed of the core to the central position between the rovings 30A and 30B is maintained, thereby always keeping the central position of the core within the outer fibers. Now, a feed of the core yarn will be explained. The bobbin 32 (Fig. 1) is for winding thereon the synthetic stretchable filament yarns such as the spandex as the core. The core yarn 34 taken out from the bobbin 32 is, via a feed roller 36, a guide roller 38 and a guide member 40 as a shape of a snail wire, is mixed with the rovings at the front roller pair 12. The core yarn 34 is under a stretched condition by a drafting of a ratio of a value such as 1.5, so that the core yarn 34 of a predetermined tension is combined to the rovings 30A and 30B. As shown in Fig. 3, the guide member 40 is mounted to the collector. As to the guide member 40 refer also to Fig. 1. Namely, the guide member 40 is, as shown, of a shape of a snail wire, which has a bottom end inserted to a bore formed in the collector and is fixed by a measure such as adhesive. During the fine spinning operation, the rovings 30A and 30B are subjected to a drafting operation at the drafting zone, which is located between the back roller pair 10 and front roller pair 12, while being guided by the groove 16-1 of the collector 16, are issued out of the front roller pair as shown by 30A-1 and 30B-1 in Fig. 4, and are wound to a paper bobbin while being subjected to a twisting. The rovings 30A-1 and 30B-1 issued from the front rollers are, first, twisted separately, are, then, gradually laterally displaced and are, finally, mutually twisted, thereby combined integrally, while the core yarn 34 introduced from the rear side of the front rollers are twisted between the rovings. As shown in Fig. 3, the collector 16 is merely freely inserted to the end of the wire shaped holder 18 which extends from the cradle (not shown) for the lower side apron 14-1 (Fig. 1). As a result, during the execution of the yarn production, the collector 16 is constantly subjected to the oscillation caused by a vibration of the machine as well as a vibration of the yarn, so that the lateral position of the collector 16 is not fixed and is constantly displaced laterally. Such a lateral displacement of the collector 16 is illustrated by an arrow F in Fig. 3. In view of this, if the core yarn 34 from the guide roller mounted to the machine frame are merely combined with the rovings 30A and 30B without use of the guide 40, the position of the rovings 30A and 30B where the core 34 is combined will be constantly laterally displaced due to the fact that the lateral position of the guide roller 38 is fixed, on one hand and, on the other hand, the collector 16 is constantly, delicately laterally displaced. In other words, the core yarn 34 can not always supplied to the central position between the rovings 30A and 30B, so that the position of the feed of the core yarn 34 to the rovings 30A and 30B is displaced from the central position, which causes a situation to be frequently arisen that the core yarn is located at the end position in the cross section of the yarn after the twisting and winding. Fig. 5B illustrates, in the prior art, the distribution of the core fibers in the yarn after execution of the twisting and winding, wherein the core fibers are moved to the outermost layer. At the location where the core is moved to the outer layer, the yam produce a sparkled appearance, which causes surface defects to be generated after the execution of the weaving or dyeing. Contrary to this, according to the present embodiment, the guide member 40 as the snail wire which effects the final guiding of the core 34 is directly fixed to the collector 16. Thus, even in a situation that the collector 16 is moved parallel to the front rollers as shown by an arrow F (Fig. 3), a movement of the guide member 40, which is in synchronous with the movement of the collector 16 as shown by the arrow F, is obtained. As a result, the core 34 is always combined with the rovings 30A and 30B guided by the collector at a central position between the rovings 30A and 30B irrespective of the lateral movement of the collector 16. As a result, in Fig. 5A, the core always occupies the central position in the cross section of the yarn. Thus, at the outlet side, the core is always located at the center of the roving issued from the front rollers, and the core is combined at the location where the rovings are integrally combined. Fig. 6 illustrates the completed state of the cored yarn. Namely, the rovings 30A-1 and 30B-1 issued from the front roller pair 12 are, first, subjected to the separate twisting, and, finally, in the state of the completed yam, the portions 30A-2 and 30B-2 from the portions 30A-1 and 30B-1, respectively are mutually twisted as shown in Fig. 6. Furthermore, the core yarn 34 is located always at the central position between the yarn portions 30A-2 and 30B-2 which are twisted. As a result, the core 34 is located at the core (center) of the outer fibers (worsted wool yam), and is prevented from being outwardly exposed, thereby preventing defect from being generated in a weaving or knitting process. As a result, a production of a cored yam which is widely received in a market becomes possible. Furthermore, due to a provision of the yarn structure of the respective yarn portions 30A-2 and 30B-2 twisted with each other while interposing the core yarn 34 therebetween, advantages are obtained that a fluffing is reduced and a brightness of the yarn is increased. Example 1 As the outer fibers anti-shrink treated wool was used. As the anti-shrink treated wool, anti-shrink treated tops which were produced by GH MICHAEL Co. in Australia were used. These tops were the ones which have an average fiber length of 65 mm. These anti-shrink treated tops were passed 6 times by an intersecting gill box, thereby producing rovings. Spandex yarns as the core were the high set type produced by Tory Du-Pont Co. in Japan (type T178C), which has a set ratio of a value in a range between 60 to 80 % under a liquid state heat treatment of a temperature in a range between 100 to 120 °C. Furthermore, the spandex yarn was the one which has total filament number of 36 and of a thickness of 18 denier and is of a covered spandex yarn having an outer surface covered by nylon filaments (30 denier thickness). Namely, as shown in Fig. 7. the core 34 has spandex filaments 34-1 which are, at their outer surface, rapped by nylon filaments 34-2. These type of the rapping yarns are available from Tory Du-Pont Co. in Japan in the trade name of a Single Covered Yarn (S.Y.C.). The two rovings as obtained above were, under a parallel condition, by using the device as shown in Figs. 1 to 4, subjected to a drafting operation and the two rovings were guided by the collector 16 while, between the two roving, the core yarn (high set type spandex yarn covered by the nylon filaments) was introduced from the rear side of the front rollers 12, thereby producing a cored yarn. In this case, the drafting ratio of the roving was 16, and the drafting ratio of the core yarn 34 was 1.3. Furthermore, the twist number per meter at the spindle was 350. As a result, a cored yarn was produced, where the high set spandex yarn as the core was twisted between anti-shrink treated wool as the outer fibers. The yarn count was 20. Furthermore, in the cored yarn, the weight ratio was 3 % of the polyurethane, 7 % of the nylon (cover yarn of the core) and 90 % of the anti-shrink treated wool. By using knitting machines of value of gauges of 5, 7, 10, 12 and 14, a knitting is done under rib stitching or plain and rib stitching, which allows to obtain clothes of a neatly knitted loops. Irrespective of the values of the gages, a stable value of the knitting density was obtained. Furthermore, the touch of the produced fabric was soft and an its outer appearance was excellent since the core yarns were prevented from being emerged outwardly. It was found that a dyeing of the fabrics by using reactive dye can produce a desired finishing and any defect can not be found since the core is prevented from being exposed outwardly. Finally, for the fabrics, a wash durability test was done under the stipulation of the Japanese Industry Standard (JIS) and any shrinkage was not generated.

Claims: A method for producing a cored yam having filament fibers (34) as a core which is covered by outer fibers, wherein rovings (30A, 30B) as the outer fibers are supplied to a drafting part of a fine spinning frame, while the filament fibers (34) are supplied via a guide member (40) to front rollers (12-1, 12-2) of the drafting part in such a manner that the filament fibers are combined with the rovings via a collector (16) which is subjected to a reciprocating movement parallel to the front rollers, characterised in that the supply of the rovings (30A, 30B) to the drafting part is such that a plurality of such rovings are fed under a parallel relationship, so that these rovings are substantially separately twisted when issuing from the drafting part, while movement parallel to the front rollers is mechanically integrated between the guide member (40) for the filament fibers (34) as the core and the collector (16) for the rovings (30A, 30B) whereby the filament fibers (34) as the core are located intermediate between said separately twisted rovings (30A-1, 30B-1) constructing said outer fibers which are finally twisted about each other to form a cored yarn. A system for producing a cored yarn, wherein it comprises a drafting part for executing a drafting operation of rovings (30A, 30B) as outer fibers, a collector (16) arranged at an inlet of front rollers (12-1, 12-2) of the drafting part for collecting and guiding the rovings (30A, 30B) toward the front rollers, feeding means for feeding filament fibers (34) to the front rollers of the drafting part so that the filament fibers (34) are combined with the rovings (30A, 30B) subjected to the drafting operation, and means for twisting and winding fibers from the front rollers, characterised in that said collector (16) has a groove (16-1) of a width which allows the plurality of rovings (30A, 30B) to be fed to the front roller while keeping said parallel condition and that a guide member (40) is mounted to the collector (16) for guiding the filament fibers (34) from the feeding means so that the filament fibers are fed to the front rollers at an intermediate position between the rovings (30A, 30B).

Inventors: SATO KOICHI, TAI MAMORU, SATO, KOICHI, TAI, MAMORU
Applicants: HIRASHIO CO LTD, HIRASHIO CO., LTD.
Application year: 2000
Main classification: D02G3
IPC codes: D02G3