Method and apparatus for manufacturing slalom false twisting on ring yarn

Abstract

In a process for manufacturing a singles ring yarn, a method and apparatus is invented which utilizes double belts as a false twist device and incorporates it in the conventional ring spinning machine for producing a singles ring yarn. In this invention, a double-belts is applied thus two twisting points, instead of one twisting point, are adopted for the yarn false twisting to improve the false twist efficiency. Accordingly, a ratio of the velocity of the belt to the delivery speed of the yarn is controlled and the wrapping angle of the yarn on the belts is adjusted in order to obtain the desired property of the final singles ring yarn. The said invention can enhance the strength of fiber strand at the spinning triangle and thus ensure the yarns spun in a normal condition at low twist multipliers, which is unable to be obtained by the conventional ring spinning machine. The method produces yarns with good strength, less hairiness and lower yarn residual torque at low twist level and endows the resultant fabric with softer handle, low spirality as well as clear and smooth surface appearance. The method and apparatus has the advantages of easy yarn piecing-up and doffing process, low spinning end-breakage when using ordinary raw materials and low cost of investment and maintenance, which not only is able to meet the commercial requirements of the large-scale production in the textile industry but also possesses a high false twist efficiency.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to spinning technology for the production of a singles ring yarn. The invention is particularly concerned with a method and apparatus that utilizes a false twist device with two false twisting points to nip yarns between double belts and incorporates it in the conventional ring spinning machine to improve yarn property and fabric performance as well as the efficiency of false twist and easiness of the operation. The false twist efficiency for yarn and thus the property of the final singles ring yarn can be controlled.

2. Background of the Invention

Twisting is an important step of short fiber spinning. In this process, the yarns, are elastically twisted and transformed to attain sufficient strength, wear resistance and smoothness. However, as a negative effect, a large amount of residual torque or twist liveliness is also brought about in the yarns simultaneously. Such twist liveliness of the yarns renders a significant influence on the possessing quality of the latter products. For example, if yarns with twist liveliness are used for knitting, loops of the fabric will lose their balance because of the residual torque in the yarns. In order to attain the natural structure with the minimum energy condition, the loops tend to rotate to release the internal torsion stress. As a result, one end of the loops will tilt and protrude from the fabric surface, while the other end will stay inside the fabric. Such deformation of the loops will increase the spirality of the fabric, i.e., a deformation similar to the rib effect, which should be prevented to the utmost in the spinning industry. Thus, the balancing of torque inside the yarns is particularly important.

Staple yarns are made from a large quantity of fibers bounded by their friction inbetween. Hence, the residual torque of the yarns or the spirality of the fabric is mainly affected by said characteristic of the fibers, such as the type and cross sectional shape of the fibers, the polymerizing manner of the fibers and the internal structure of the yarns, etc.

First of all, different types of fibers have a different modulus and cross sectional shape, thus lead to different degree of stress in the yarns. In the cotton/polyester blended yarns, increasing the ratio of polyester will enhance the twist liveliness of rotor and ring yarns, heat setting can improve the spirality of the resultant fabrics. This is because polyester has a higher modulus, and said two types of fiber have different cross sectional shapes.

Next, different yarn structures have a different distribution of stress. Experimental results, such as Barella and Manich in the Textile Research Journal, Vol. 59, No. 12, 1989, Lord and Mohamed in the Textile Research Journal, Vol. 44, No. 7, 1974 and Sengupta, and Sreenivasa in the Textile Research Journal, Vol. 64, No 10, 1994 showed that, friction yarns (DREF-II) have the largest residual torque and trend of deformation in the priority sequence followed by ring yarns, rotor yarns and air-jet yarns. It is generally agreed that single ring yarns are composed of a plurality of uniformly enveloped concentric helical threads, while fiber migration is a secondary feature. Hence, when the ring yarns are reverse-twisted, their strength will gradually decreases to zero, by then the yarns will be all dispersed. In relation to ring yarns, unconventional spinning systems produce yarns with core-sheath structures, such as rotor spinning yarn, air jet spinning yarn and friction spinning yarns. The packing density of said yarns is uneven and mainly characterized in the partial entanglement and entrapment of the fibers.

In addition, many factors can affect the degree of movement freedom of the loops of the fabric and also the final spirality of the fabric. Said factors include fabric structure, parameters of the knitting machine, and the fabric relaxation and fabric setting due to finishing. All the aforesaid factors affecting the spirality of fabric were reported in detail by Lau and Tao in the Textile Asia, Vol. XXVI, No. 8, 1995.

Same as other materials, the residual torque of the yarns can be reduced or eliminated with different methods. In the past several decades, a variety of torque balancing methods have been developed. According to the basic theory, they can generally be split into two categories: permanently processing methods and physical torque balancing methods.

Permanently setting methods mainly accomplish the purpose of releasing residual torque by transforming the elastic torsional deformation into plastic deformation. The method mainly relates to a variety of setting techniques for material, such as thermal setting, chemical processing and wet setting etc. In the Textile Research Journal, Vol. 59, No. 6, 1989, Araujo and Smith have proved that for air-jet and rotor yarns, the heat setting of single cotton/polyester blended yarns can effectively reduce the residual torque of the yarn. However, in relation to natural fibers such as cotton or wool, permanent setting is too complicated. It may involve steaming, hot water and chemical processing (such as mercerization in the case of cotton yarns and treatment with sodium bisulphite in the case of the wool yarns). In addition, in relation to natural yarns, setting cannot completely eliminate the residual torque of the single yarns, and it may also cause damage to the yarns.

Compared with permanent processing, physical torque balancing is a pure mechanical processing technique. The main point of the method is to fully utilize the structure of yarns to balance the residual torque generated in different yarns while maintaining the elastic deformation characteristic of the yarns. Currently in the industry, separate machines are required to enforce torque balancing of the yarns hence the cost is higher. The method comprises plying two identical singles yarns with a twist equal in number but in the opposite direction to that in the singles yarns; or feeding two singles yarns with twist of the same magnitude but in opposite direction onto the same feeder.

Recently, some new torque balancing methods for yarns also emerged in the Textile Research Journal, Vol. 65, No. 9, 1995, Sawhney and Kimmel described a series spinning system for processing torque-free yarns. The inner core of said yarns is formed by processing with an airjet system while outside the core is enwrapped with crust fibers similar to DREF-III yarns. In the Textile Research Journal, Vol. 62, No. 1, 1992, Sawhey etc. have suggested a method of processing ring cotton crust/polyester inner core yarns. Said yarns accomplish balancing condition by utilizing core yarns with opposite twisting direction from synthetic yarns, or applying heat processing on the polyester portion of said yarns. However, it is readily seen that the machines and processing techniques related to the aforesaid method are generally more complicated. In the Textile Research Journal, Vol, 57, No. 10, 1997, Tao has processed the layer structure of the inner core-crust of rotor yarns to generate torque-free single yarns, yet said technique is not suitable for ring yarns.

In addition, U.S. Pat. No. 6,860,095 B2, filed by Tao et al. discloses a method of producing torque-free singles ring yarns. According to this patent application, a draft fiber is divided into a plurality of sub-assemblies of fibers. Each sub-assembly of fibers firstly attains an individual twist value during a false twisting, and then are twisted together to form the final yarns. The false twisting is controlled such that balance of the internal torque of the final yarns is achieved. Furthermore, U.S. Pat. No. 7,096,655 B2 filed by Tao et al. discloses a method and apparatus for producing a singles ring yarn. In this method, a false twist device rotates at a first speed for twisting the fibers. Immediately after the first twisting step, a joint twist of the second twist in the same direction as the first twist and a third twist in a reversed direction is supplied to the preliminary yarn for producing final singles ring yarn. Moreover, a ratio of first speed to the second speed is controlled for controlling the residual torque in the final singles ring yarn.

The aforementioned patents present the method and apparatus for singles ring yarn. However, the abovementioned patent application is more appropriate for torque-free singles ring yarn production in the laboratory scale. The yarn piecing-up and doffing process can not completely be able to meet the practical requirements of the largescale production in the textile industry. Furthermore, the spinning end-breakage when using ordinary cotton and the cost of investment and maintenance need to be further reduced for the widely commercial application. In order to overcome the above shortcomings, two twisting points, instead of one twisting point, are adopted for the yarn false twisting to obtain the high false twist efficiency in this invention. In addition, a ratio of the velocity of the belt to the delivery speed of the yarn is controlled and the wrapping angle of the yarn on the belts is adjusted in order to obtain the desired property of the final singles ring yarn.

OBJECT OF THE INVENTION

Therefore, it is an objective of the present invention to provide an improved method and apparatus for producing singles ring yarns. The method and apparatus has the actual advantages of easy yarn piecing-up and doffing process, low spinning endbreakage when using ordinary raw materials and low cost of investment and maintenance, which not only is able to meet the commercial requirements of the large-scale production in the textile industry but also possess high false twist efficiency, wherein instead of one twisting point, two twisting points are adopted for the yarn false twisting to improve the false twist efficiency, and wherein the false twist efficiency is controlled such that the desirable lower residual torque as well as other yarn properties can be achieved. Accordingly, a ratio of the velocity of the belt to the delivery speed of the yarn is controlled and the wrapping angle of the yarn on the belts is adjusted in order to obtain the desired property of the final singles ring yarn.

SUMMARY OF THE INVENTION

According to an aspect of present invention, a method for producing singles ring yarns is as follows.

A first high twist is imparted to a strand of traveling drafted fibers emerged from the front-drafting-roller nip with the upper belt of a false twist device for producing a preliminary singles yarn, wherein the belt travels at the velocity of the belt for twisting the fibers and thus the strength of fiber strand is enhanced at the spinning triangle when a low twist level is adopted in the final singles yarn. Immediately after the false twist step by the upper belt severed as the first twisting point, a joint twist of a second twist in the same direction as the first twist and a third twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the second twist is produced by a running of the lower belt on the yarn, wherein the third twist results in correspondence to the first twist by a running of the upper belt on the yarn. Immediately after the false twist step by the lower belt severed as the second twisting point, a joint twist of a forth twist in the same direction as the second twist, and a fifth twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the forth twist is produced by a rotatable take-up package of the ring spinning machine onto which the final singles yarn is drawn, wherein the fifth twist results in correspondence to the second twist by a running of the lower belt on the yarn. Then the final singles yarn was drawn onto the take-up package. The upper and lower belts run in the same velocity.

Controlling a ratio of the velocity of the belts to the delivery speed of the yarn and the wrapping angle of the yarn on the belts can control the false twist efficiency for yarn and thus the yarn property.

According to another aspect of present invention, an apparatus for producing singles ring yarns is as follows.

The upper belt of a false twist device travelling at the velocity of the belt imparts a first high twist to a strand of travelling drafted fibers emerged from the front-drafting roller nip such that a preliminary singles yarn is produced. The lower belt of a false twist device travelling at the same velocity as the upper belt imparts a second twist in the same direction as the first twist to a preliminary singles yarn emerged from the upper belt such that a further preliminary singles yarn is produced. A rotatable take-up package onto which the final singles yarn is drawn imparts a fourth twist in the same direction as the first twist and second twist to a preliminary singles yarn emerged from the lower belt such that final singles yarn is produced, wherein the double belt travels at the velocity of the belt for twisting the fibers and thus the strength of fiber strand is enhanced at the spinning triangle when a low twist level is adopted in the final singles yarn, wherein a joint twist of a second twist in the same direction as the first twist and a third twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the second twist is produced by a running of the lower belt on the yarn, wherein the third twist results in correspondence to the first twist by a running of the upper belt on the yarn, wherein the yarn was drawn onto the take-up package at the delivery speed of the yarn, wherein a joint twist of a forth twist in the same direction as the second twist and a fifth twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the forth twist is produced by a rotatable take-up package onto which the final singles yarn is drawn, and wherein the fifth twist results in correspondence to the second twist by a running of the lower belt on the yarn.

A ratio of the velocity of the belts to the delivery speed of the yarn can be controllable and the wrapping angle of the yarn on the belts is adjustable such that the false twist efficiency and the yarn property can be adjusted.

Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which description illustrates by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side diagrammatic plan view of a spinning apparatus in accordance with an exemplary embodiment of the present invention;

FIG. 2 is a schematic representative in perspective, of a spinning apparatus in accordance with an exemplary embodiment of the present invention;

FIG. 3 is a side enlargement of part of FIG. 1 showing the geometry interrelations of the yarn, the upper belt and lower belt;

FIG. 4 is alternative of a side diagrammatic plan view of a spinning apparatus in accordance with an exemplary embodiment of the present invention with a nip false twister consisting of the two belts;

FIGS. 5A and 5B are two alternatives of a side diagrammatic plan view of a spinning apparatus of an exemplary embodiment of the present invention shown in FIG. 1 with core spandex/filament;

FIGS. 6A and 6B are two alternatives of a side diagrammatic plan view of a spinning apparatus of an exemplary embodiment of the present invention shown in FIG. 4 with core spandex/filament;

FIG. 7 is an alternative of a side diagrammatic plan view of a spinning apparatus of an exemplary embodiment of the present invention with two belts running in cross direction and regulation block;

FIG. 8 is another alternative of a side diagrammatic plan view of a spinning apparatus of an exemplary embodiment of the present invention with two belts driving individually and running in cross direction;

FIG. 9 is another alternative of a top diagrammatic plan view of a spinning apparatus in accordance with an exemplary embodiment of the present invention with a nip false twister consisting of the two belts arranged in concentric circle;

FIG. 10 illustrates ten alternatives of a cross-sectional profile of the false twist belt shown in FIGS. 1-9;

FIG. 11 is a diagrammatic view of the modified curves of vertical positions relative to time of a ring for yarn doffing.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate a side diagrammatic plan view and a schematic representative in perspective of a spinning apparatus in accordance with an exemplary embodiment of the present invention, respectively. As shown in FIGS. 1 and 2, a roving 101 is delivered through the drafting system 103, 105 and 107, including a pair of back drafting rollers 103, a pair of aprons 105, and a pair of front drafting rollers 107. The drafted roving is twisted by the upper belt 111 of a false twist device 102 to form a preliminary singles yarn wherein the false twist for a yarn is provided by the running action of the upper belt 111. Immediately after the false twist step by the upper belt 111 severing as the first twisting point, a joint twist of a second twist in the same direction as the first twist and a third twist in the reversed direction are imparted to the preliminary singles yarn 106 for the production of a final singles ring yarn, wherein the second twist is produced by a running of the lower belt 113 on the yarn, wherein the third twist results in correspondence to the first twist by a running of the upper belt 111 on the yarn.

Immediately after the false twist step by the lower belt 113 severing as the second twisting point, a joint twist of a forth twist in the same direction as the first twist and second twist, and a fifth twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn 104, wherein the forth twist is produced by a rotatable take-up package 121 onto which the final singles yarn is drawn, wherein the fifth twist results in correspondence to the second twist by a running of the lower belt 113 on the yarn. Then the yarn 104 proceeds to a yarn guide 115, and then further to a bobbin 121. The yarn 104 becomes wound on the bobbin 121 via a traveler 117 moving on a ring rail 119.

As shown in FIGS. 1 and 2, the double-belts twisting device 102 includes, in addition to other components, primarily an upper belt 111 and a lower belt 113. In the false twisting device 102, the upper belt 111 and the lower belt 113 are travelling in opposite directions with the same velocity. The yarn 109 interacts with the false twisting device 102 in a slalom-like arrangement with two false twisting points, i.e., the yarn 109 interacts with the outer surface on one belt which severs as the first twisting point, then interacts on the inner surface of the other belt which severs as the second twisting point. In this case, the yarn 109 interacts with the outer surface of the upper belt 111 first then diverges to the inner surface of the lower belt 113, before exiting the false twister. In fact, the yarn is false twisted by the torque generated by running the double belts in opposite travelling directions.

Furthermore, in the exemplary embodiment, there are two false twisting points of a false twist device by the travelling upper belt and lower belt for the yarn. The false twist efficiency for the yarn depends on the friction between the yarn and the surface of the upper belt and lower belt, and the ratio of the velocity of the belts to the delivery speed of the yarn. The residual torque and other yarn properties of the final singles ring yarn are controlled by controlling the friction between the yarn and the surface of the upper belt and lower belt, and the ratio of the velocity of the belts to the delivery speed of the yarn.

The belt can be driven by a conveyor belt 209 having two or more pulleys 207, whereby at least one of the pulleys 207 is attached to a motor 211. The motor 211 is controlled by suitable electronics such as inverters 213. The motor 211 has the capability to drive the conveyor belt and further drive the double belts with a controllable ratio of the velocity of the belts to the delivery speed of the yarn predetermined by the desired impartation of false twist and thus the resultant amount of a residual torque as well as other yarn performance in the final singles ring yarn.

An additional yarn guide 110 installed above the upper belt 111 for each spindle is used to control the yarn movement during the spinning. The positioning of the yarn guide 110 should be aware in the installation. Exceed amount of friction between yarn guide and yarn results in the yarn breakage where insufficient amount of false twist results in the poor yarn strength. Several belt guides 203, installed on the both sides of the double belts 111 and 113, and several pressuring discs 201, installed on upper and below sides of the belts 111 and 113, are used to control the belts movement, as well as adjust the geometry interrelations of the yarn and the upper belt and lower belt and the tension of the belts. Through the belt guides 203, pressuring discs 201 and the wheels 205, the belts are maintained in a stable condition with predetermined tension. FIG. 3 is a side enlargement of part of FIG. 1 showing the geometry interrelations of the yarn, the upper belt 111 and lower belt 113; As shown in FIG. 3, “_—1”, “_—2” and “_—3” represent the crossing angles of the straight line (O₁O₂) with respect to the travelling path of the yarn portions 109, 106 and 104 respectively, wherein “O₁” is the center of the upper belt and “O₂” is the center of the lower belt. “_—1” and “_—2” represent the wrapping angles of yarn portions on the upper belt and lower belt, respectively. “L” represents the length of the straight line which connects the center (O₁) of the upper belt and the center (O₂) of the lower belt. The geometry interrelation of the yarn, the upper belt and lower belt which is described by the crossing angles (_—1, _—2 and _—3), wrapping angles (_—1 and _—2) and the length of the straight line (O₁O₂) is important in determining the optimal adaptation of the double-belts false twist device to the desired impartation of false twist, and in optimizing the yarn tension conditions. FIG. 4 is alternative of a side diagrammatic plan view of a spinning apparatus in accordance with an exemplary embodiment of the present invention with a nip false twister 102 consisting of the two belts. As shown in FIG. 4, the drafted roving is twisted by being contacted from opposite sides by the travelling upper belt 111 and lower belt 113 of a false twist device 102 to form a preliminary singles yarn wherein the false twist for a yarn is provided by the running action of the upper belt and lower belt 113 travelling in opposite direction. FIG. 4 provides the false twist device with one twisting point instead of two twist points shown in FIG. 1. Compared to the one belt false twisting device, the nip false twister can increase the pressure between the yarn and the belts.

FIGS. 5A and 5B are two further embodiments of apparatus of the present invention as well as method shown in FIG. 1 for the core spandex/filament yarn. FIG. 5A provides an apparatus of the present invention for the core spandex/filament singles ring yarn. The spandex/filament 501 is delivered by feed rollers 503 and turning rollers 505 and then fed into the front rollers 107. The draft ratio is controlled by the surface speed ratio of the front rollers 107 to the feed rollers 503. FIG. 5B provides another apparatus of the present invention for the core spandex/filament singles ring yarn. The spandex/filament 501 is also delivered by feed rollers 503 and turning rollers 505 and then fed into the drafting system including a pair of back drafting rollers 103, a pair of aprons 105, and a pair of front drafting rollers 107. The draft ratio is controlled by the draft ratio of the drafting system and the surface speed ratio of the back rollers 103 to the feed rollers 503. Emerging from the front roller nip, the core spandex/filament and fibers twisted together by running the belts of the false twist device 102 and then rotating the take-up package 121 to form the final core spandex/filament singles ring yarn 104.

FIGS. 6A and 6B are other two further embodiments of apparatus of the present invention as well as method shown in FIG. 4 for the core spandex/filament yarn. FIG. 6A provides an apparatus of the present invention for the core spandex/filament singles ring yarn. The spandex/filament 501 is delivered by feed rollers 503 and turning rollers 505 and then fed into the front rollers 107. The draft ratio is controlled by the surface speed ratio of the front rollers 107 to the feed rollers 503. FIG. 6B provides another apparatus of the present invention for the core spandex/filament singles ring yarn. The spandex/filament 501 is also delivered by feed rollers 503 and turning rollers 505 and then fed into the drafting system including a pair of back drafting rollers 103, a pair of aprons 105, and a pair of front drafting rollers 107. The draft ratio is controlled by the draft ratio of the drafting system and the surface speed ratio of the back rollers 103 to the feed rollers 503. Emerging from the front roller nip, the core spandex/filament and fibers twisted together by running the belts of the false twist device 102 and then rotating the take-up package 121 to form the final core spandex/filament singles ring yarn 104.

FIG. 7 is another embodiment of apparatus of the present invention as well as method with double belts running in cross direction and regulation block for the friction adjusting between the yarn and belts. As shown in FIG. 7, the outer face of the outer belt 701 is disposed in an opposing, substantially non-contacting relationship with the outer face of the inner belt 703, and defines a gap there between. A yarn 109 is advanced along the line which bisects the angle formed by the two crossing belts, and through the twisting zone composed of the opposing belts 701 and 703 overlapped. The belts are pressed against the yarn in the area of the twisting zone by the regulation block 705 which consists of spring and shim assembly. The regulation block can adjust the friction between the yarn and belts, improve the control of fiber movement during the false twisting of the yarn, provide an easier yarn piecing process as well as increase the false twist efficiency.

FIG. 8 is another alternative of a side diagrammatic plan view of a spinning apparatus of an exemplary embodiment of the present invention with two belts driven individually and running in cross direction; As shown in FIG. 8, the outer face of the outer belt 801 is disposed in an opposing, substantially non-contacting relationship with the outer face of the inner belt 803, and defines two gaps there between. A yarn 109 is advanced along the line which bisects the angle formed by the two crossing belts, and through the twisting zone composed of the opposing belts 801 and 803 overlapped. FIG. 8 provides the false twist device with two twisting point instead of one twist points shown in FIG. 7. Compared to the false twist device shown in FIG. 7, the false twist device shown in FIG. 8 can adjust the contact area between the yarn and belts to further improve the control of fiber movement during the false twisting of the yarn, increase the false twist efficiency as well as provide an much easier yarn piecing process.

FIG. 9 is another alternative of a top diagrammatic plan view of a spinning apparatus in accordance with an exemplary embodiment of the present invention with a nip false twister consisting of the two belts arranged in concentric circle. As shown in FIG. 9, the yarn 109 is false twisted by the running action of outer belt 901 and inner belt 903 travelling in opposite direction in a false twist device to form a preliminary singles yarn. The outer belt 901 and inner belt 903 can be driven individually in high velocity as well as in more stable running condition to increase the false twist efficiency. FIG. 10 illustrates ten alternatives of a cross-sectional profile of the false twist belt shown in FIGS. 1-9. The belt profile particularly the shape of the contacting section of the belt with the yarn, the hardness as well as the surface property of the belt are important for false twisting effects. The round shape and elliptical shape illustrated by the cross-sectional profiles 1001 and 1003 for the belt are two desirable contacting shapes with the yarn during the yarn false twisting. The cross-sectional profile 1001′ and 1003′ for the belt are another two alternatives with hollow inside the belt which results in the reduction of hardness of the belt and thus changes the friction between the yarn and the belt. All these four types of belt shapes can be used for the yarn false twisting process showed in FIGS. 1-6, and which one is to be used mainly depends on the required false twisting effects. The cross-sectional profiles 1005, 1007 and 1009 are the other three shapes for the belt and the cross-sectional profiles 1005′, 1007′ and 1009′ are their corresponding three alternatives with hollow inside the belt, wherein the top shape is for the contacting area of the belt with the yarn. All these six types of belt shapes can be used for the yarn false twisting process showed in FIGS. 7-9. FIG. 11 is a diagrammatic view of the modified curves of vertical positions relative to time of a ring for yarn doffing. The modifications have been proposed on the conventional doffing process to avoid yarn snap during doffing process. In FIG. 11, 1101 and 1103 are respectively the modified curves of the mean vertical position and the resultant vertical position of the ring rail. Two axes of the coordinates represent time 1105 and vertical position 1107, respectively. According to an exemplary embodiment of the present invention, the spinning apparatus is powered off at time 1109 which should be matched to the power off time of the motor 211 when the ring rail moves upwards to the up-most position. Thereafter, the ring rail is waited for a predetermined period of time 1111. Then it is finally pulled down the ring gradually at the winding time 1115 until the ring completely stops at the termination time 1117, wherein 1113 indicates the total stop period of time.

Claims

1. A method for producing singles ring yarns, comprising:

imparting a first high twist to a strand of traveling drafted fibers emerged from the front-drafting-roller nip with the upper belt of a false twist device for producing a preliminary singles yarn, wherein the belt travels at the velocity of the belt for twisting the fibers and thus the strength of fiber strand is enhanced at the spinning triangle when a low twist level is adopted in the final singles yarn;

immediately after the false twist step by the upper belt severed as the first twisting point, imparting a joint twist of a second twist in the same direction as the first twist and a third twist in the reversed direction to the preliminary singles yarn for the production of a final singles ring yarn, wherein the second twist is produced by a running of the lower belt on the yarn, wherein the third twist results in correspondence to the first twist by a running of the upper belt on the yarn;

immediately after the false twist step by the lower belt severed as the second twisting point, imparting a joint twist of a forth twist in the same direction as the second twist, and a fifth twist in the reversed direction to the preliminary singles yarn for the production of a final singles ring yarn, wherein the forth twist is produced by a rotatable take-up package of the ring spinning machine onto which the final singles yarn is drawn, wherein the fifth twist results in correspondence to the second twist by a running of the lower belt on the yarn; then the final singles yarn was drawn onto the take-up package;

running the upper and lower belts in the opposite directions with the same velocity; and

controlling a ratio of the velocity of the belts to the delivery speed of the yarn and the wrapping angles of the yarn on the double-belts for controlling the false twist efficiency for yarn and thus the yarn property.

2. The method for producing singles ring yarns of claim 1, wherein the yarn interacts with the false twisting device in the form of two false twisting points and in fact the yarn is false twisted by the torque generated by running the double belts in opposite travelling directions with the same velocity.

3. The method for producing singles ring yarns of claim 1, wherein the geometry interrelation of the yarn, the upper belt and lower belt is important in determining the optimal adaptation of the double belts false twist device to the desired impartation of false twist, and in optimizing the yarn tension conditions and false twist efficiency.

4. The method for producing singles ring yarns of claim 1, wherein the residual torque and other yarn properties of the final singles ring yarn are controlled by controlling the friction between the yarn and the surface of the upper belt and lower belt, and the ratio of the velocity of the belts to the delivery speed of the yarn.

5. The method for producing singles ring yarns of claim 1, wherein the high false twist efficiency that utilizes double belts as a false twist device is provided during the yarn spinning process, and wherein the ordinary raw materials can be used to produce singles ring yarn due to the improved strength of fiber strand in the spinning triangle and the improved fiber inter-friction within the yarn at a low twist level.

6. An alternative method for producing singles ring yarns, comprising:

imparting a first high twist to a strand of traveling drafted fibers emerged from the front-drafting-roller nip with a nip false twister consisting of the two belts in close position for producing a preliminary singles yarn, wherein the false twist device provides one twisting point instead of two twist points for a yarn, wherein the false twist device provides more false twist efficiency than that of one belt false twist device, and wherein the yarn is false twisted by the torque generated by running the double belts in opposite travelling directions with the same velocity.

7. An another alternative method for producing singles ring yarns, comprising:

imparting a first high twist to a strand of traveling drafted fibers emerged from the front-drafting-roller nip with double belts running in cross direction and regulation block for the friction adjusting between the yarn and belts for producing a preliminary singles yarn, wherein a yarn is advanced along the line which bisects the angle formed by the two crossing belts, i.e., the false twisting zone.

8. The method for producing singles ring yarns of claim 7, wherein the belts are pressed against the yarn in the area of the twisting zone by the regulation block which consists of spring and shim assembly, and wherein the regulation block can adjust the friction between the yarn and belts, improve the control of fiber movement during the false twisting of the yarn as well as provide a easier yarn piecing process.

9. An apparatus for producing singles ring yarns, comprising:

the upper belt of a false twist device travelling at the velocity of the belt imparting a first high twist to a strand of travelling drafted fibers emerged from the front drafting-roller nip such that a preliminary singles yarn is produced;

the lower belt of a false twist device travelling at the same velocity as the upper belt imparting a second twist in the same direction as the first twist to a preliminary singles yarn emerged from the upper belt such that a further preliminary singles yarn is produced;

a rotatable take-up package onto which the final singles yarn is drawn imparting a fourth twist in the same direction as the first twist and second twist to a preliminary singles yarn emerged from the lower belt such that final singles yarn is produced, wherein the double belt travels at the velocity of the belt for twisting the fibers and thus the strength of fiber strand is enhanced at the spinning triangle when a low twist level is adopted in the final singles yarn, wherein a joint twist of a second twist in the same direction as the first twist and a third twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the second twist is produced by a running of the lower belt on the yarn, wherein the third twist results in correspondence to the first twist by a running of the upper belt on the yarn, wherein the yarn was drawn onto the take-up package at the delivery speed of the yarn, wherein a joint twist of a forth twist in the same direction as the second twist and a fifth twist in the reversed direction are imparted to the preliminary singles yarn for the production of a final singles ring yarn, wherein the forth twist is produced by a rotatable take-up package onto which the final singles yarn is drawn, and wherein the fifth twist results in correspondence to the second twist by a running of the lower belt on the yarn, wherein the ratio of the velocity of the belts to the delivery speed of the yarn can be controllable and the wrapping angle of the yarn on the belts is adjustable such that the false twist efficiency and the yarn property can be adjusted.

10. The apparatus of claim 9, wherein the false twisting device mainly comprise the double belts severed as two false twisting points when the double belts travel in opposite travelling directions with the same velocity.

11. The apparatus of claim 9, wherein the belt guides and pressuring discs are used to control the belts movement, as well as adjust the geometry interrelations of the yarn and the upper belt and lower belt and the tension of the belts.

12. An alternative apparatus for producing singles ring yarns, comprising:

a nip false twister consisting of the two belts in close position imparting a first high twist to a strand of traveling drafted fibers emerged from the front-drafting-roller nip for producing a preliminary singles yarn, wherein the false twist device provides one twisting point instead of two twist points for a yarn, and wherein the yarn is false twisted by the torque generated by running the double belts in opposite travelling directions with the same velocity.

13. An another alternative apparatus for producing singles ring yarn, comprising:

a false twist device with double belts running in cross direction imparting a first high twist to a strand of traveling drafted fibers emerged from the front-drafting-roller for producing a preliminary singles yarn, wherein a yarn is advanced along the line which bisects the angle formed by the two crossing belts, i.e., the false twisting zone.

14. The apparatus of claim 13, wherein the belts are pressed against the yarn in the area of the twisting zone by the regulation block which consists of spring and shim assembly, and wherein the regulation block can adjust the friction between the yarn and belts, improve the control of fiber movement during the false twisting of the yarn as well as provide a easier yarn piecing process.

15. The apparatus of claim 9, wherein ten different types of belt shapes such as round shape, elliptical shape and with/without hollow inside the belt for the false twist device can be used for the yarn false twisting process and which one is to be used mainly depends on the required false twisting effects.

16. The apparatus of claim 12, wherein ten different types of belt shapes such as round shape, elliptical shape and with/without hollow inside the belt for the false twist device can be used for the yarn false twisting process and which one is to be used mainly depends on the required false twisting effects.

17. The apparatus of claim 13, wherein ten different types of belt shapes such as round shape, elliptical shape and with/without hollow inside the belt for the false twist device can be used for the yarn false twisting process and which one is to be used mainly depends on the required false twisting effects.