Title of Invention

"AN IMPROVED CRADLE ROLLER"

Abstract

An improved cradle roller for use in a drafting apparatus at the ring spinning frame comprising: - a shaft with a top end and a bottom end, said top end having a bearing mounted within a housing characterized in that the bottom end of the shaft being surrounded by a bearing having a steel casing mounted thereon, - said steel casing having a layer of rubber of predetermined diameter on its outer surface said rubber layer being provided with a groove at both ends so as to maintain the contact pressure in the contact region, thereby providing a better control of the short fibers in the yarn.

Full Text

The present invention relates to an improved cradle roller for use in a drafting apparatus of a ring spinning frame. Background: The invention relates to the field of spinning cotton as a fiber into final yarn capable of being used for making fabric. Cotton is a natural fiber and is available from various sources across the globe. However, the fiber as available contains a lot of trash, such as, dust, leaves, husk etc. Such fiber cannot be used for making yarn. Fibers less than 12.5mm in length or ½ inch are referred to as short fibers. Short fibers result in unevenness, reduction in strength of the yarn and also adversely affect the yarn spinning process. Fiber control deteriorates as the short fiber content in the input material goes up. This results in imperfections and faults in the yarn, which significantly affects the fabric appearance. In addition, cotton fiber, even from the same source may be different in texture. The yarn spinning process thus aims at overcoming these drawbacks and producing strong and even yarn. Spinning of yarn may be broadly classified into the following stages: blowing, carding, combing, drawing, roving and production of final yarn at the ring frame. Blowing of the fiber takes place in the blow room where trash from the fiber is removed. Bales of fiber are separated and close to 50 - 70 % of the trash is removed at this stage. The bale of fiber is then converted into strands of fiber over the next couple of stages. Fiber from the blow room is then sent to the carding stage wherein separation and straightening of fibers is carried out. The fiber is passed through a series of rollers that also remove most of the remaining trash in the fiber. The carding stage also removes short lumps of cotton formed in the fiber known as neps. The carding stage also aims at reducing the short fibers in the yarn. The output of the carding stage is referred to as the carded sliver. The carding stage thus converts lumps of cotton into strands or slivers. Some short fibers and neps remain in the carded sliver. The carded sliver may be sent straight to the drawing stage or a combing stage may be introduced depending on the quality of yarn requirement. For economic quality yarn the combing stage may be skipped. Yarn leaving the combing stage is referred to as combed sliver. However, if the quality of fiber used is not top grade then the carded sliver contains a significant amount of short fibers that are detrimental to the final yarn, thus necessitating the combing stage. The combing stage involves removal of short fibers and neps. Short fibers removed from the combing stage are referred to as process waste and ranges from 16% to 25% depending on yarn quality. The lesser the number of short fibers in the yarn the higher the strength of the yarn. The combed yarn is thus more even and stronger than the carded yarn. The combing operation however, results in a considerable waste of raw material. Drafting is the process of attenuating a strand of fibers, with the intention of orienting the fibers in the direction of the strand and reducing its linear density. In a roller drafting system, the strand is passed through a series of sets of rollers, each successive set rotating at a surface speed greater than that of the previous set. During drafting, the fibers must be moved relative to each other as uniformly as possible by overcoming the cohesive friction. Uniformity implies in this context that all fibers are controllably rearranged with a shift relative to each other equal to the degree of draft. Attenuating a fiber refers to making the final yarn thinner and finer. For example, fiber weighing 4.5gm/meter after carding is attenuated to 0.5gm/meter in roving, and further attenuated to 0d^gm/meter on the ring frame. Drafting is carried out at the draw frame during drawing, at the roving frame during roving and at the final stage of yarn production at the ring spinning stage. Combed sliver from the combing stage is sent to the draw frame for the drawing operation. The draw frame is where blending and evening out of fibers is carried out. As many as 8 slivers are used and these are blended to increase the evenness. Evening out the fibers involves further attenuating the fiber by a factor proportional to the number of slivers used and then blending the slivers to attain the final drawing sliver of the same linear density. For example, if six slivers are drawn then these slivers are attenuated by a factor of 6 making each sliver 1/6 of its initial density and then blending of the six attenuated slivers is carried out to attain the drawing sliver of the original density. The drawing sliver is more homogenous and has greater evenness. This has been illustrated in figure 5 of the accompanying drawings. Drawing sliver is then sent to the roving frame where further attenuation of the sliver is carried out to form Roving and is then sent to the ring spinning frame from where the final yarn is produced. The ring spinning frame is the most critical stage in that the final yarn is produced here. The invention in particular relates to the drafting carried out at the ring spinning frame, and more specifically to the Reiter R2P drafting system with P 3-1 guide arm. Improvements and modifications in the said ring spinning frame and in particular the cradle roller are described, which allow the same machine to provide better yarn without having to replace the entire machine. Summary and Objectives of Invention: In order to overcome the above limitations the invention provides tor an improved drafting apparatus. It is an object of the invention to improve the spinning process and in particular the cotton spinning process. It is an object of the invention to control the movement of short fiber during ring frame drafting operation. It is an object of the invention to reduce process waste and thereby save costs. It is an object of the invention to reduce yarn imperfections and provide better quality yarn. It is an object of the invention to provide for an apparatus that does not necessitate the replacement of the entire spinning machine. To meet the aforementioned objectives the invention provides for An improved cradle roller for use in a drafting apparatus at the ring spinning frame comprising: - a shaft with a top end and a bottom end, said top end having a bearing mounted within a housing characterized in that the bottom end of the shaft being surrounded by a bearing having a steel casing mounted thereon, - said steel casing having a layer of rubber of predetermined diameter on its outer surface said rubber layer being provided with a groove at both ends so as to maintain the contact pressure in the contact region, thereby providing a better control of the short fibers in the yarn. Brief Description of the Accompanying Drawings: The accompanying drawings illustrate preferred embodiments of the invention and together with the following detailed description, serve to explain the principles of the invention. Figure 1 illustrates the drafting apparatus as employed by the Reiter Machine Figure 2 illustrates the side view of the cradle roller of the drafting apparatus as illustrated by figure 1. Figure 3 illustrates the drafting apparatus in accordance with this invention. Figure 4 illustrates the side view of the cradle roller in accordance with this invention. Figure 5 illustrates a schematic of the drawing process. Figure 6 depicts the construction of the cradle roller in accordance with the invention. Detailed description of Invention: It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof. Through out the patent specification, a convention employed is that in the appended drawings, like numerals denote like components. Figure 1 illustrates the Reiter drafting apparatus at the ring spinning frame. The drafting apparatus comprises of a series of rollers and aprons. The aprons are belts, made preferably of rubber, that control the fiber movement and serve as guides to the fibers as it passes through the rollers. As shown the drafting apparatus comprises of the following rollers: a front top roller (20) and a front bottom roller (18), a middle top roller also known as the 'cradle roller' (14) and a middle bottom roller (16), and lastly a rear top roller(l0) and a rear bottom roller(12). A top apron (13) and a bottom apron (15) are wound around the cradle roller and the middle bottom roller as shown. To support the aprons in their path around the rollers there is provided a cradle (11) and an apron bridge (17) as shown. The distance between the cradle roller and the rear top roller is 62 mm. Dimensions and distances are as shown in figure 1. Figure 2 illustrates the cradle roller of the Reiter drafting apparatus in detail. The diameter of the cradle roller is 27mm and is 28.5 mm in length. The other dimensions and distances are as shown in figure 2. The invention will now be described with reference to figure 3. In order to achieve better control and reduction of short fibers, the cradle roller diameter has been reduced from 27 mm to 25 mm. The reduction in diameter will lead to a reduction in contact pressure between the roller and the apron, which may result in apron slippage and inadequate holding power of the cradle roller. To offset this, a groove of 5mm has been provided on both ends of the cradle roller, thereby reducing area of contact between the cradle roller and the middle bottom roller to 18.5mm and maintaining pressure at the area of contact the same. The cradle roller in accordance with the invention and comprising of the aforementioned modifications is illustrated in figure 4. The cradle roller comprises of a shaft that is mounted in a housing through bearings at one end, also referred to as the top end. At the other end or bottom end, the shaft (24) is also mounted with bearings (26) that in turn are covered with a steel shell (28). A layer of rubber (30) with grooves (32) that forms the outer surface of the cradle roller surrounds the steel shell. A cross section of the cradle roller in accordance with the invention and having the groove has been shown in figure 5. The top apron diameter has also been reduced from 39.2 mm to 38 mm, again resulting in better control of fibers. As the area of contact between the cradle roller and the middle bottom roller has been reduced the width of the apron has been reduced from 30 mm to 24mm. In accordance with another aspect of the invention the aprons for the drafting system have been modified. Presently used aprons have a normal surface finish on the top surface, a plain surface on the inside surface and coarse inside chord. The aprons in accordance with this invention have been provided with a rough surface finish on the top surface, a grooved surface on the inside surface and a fine inside chord. The apron is made of synthetic rubber. The apron in accordance with this invention provides low torque during bending and flexing movement, good grip on holding elements such as the cradle roller, bottom roller and the apron bridge bar. The better surface characteristics aid the improved drafting as set forth by this invention. In accordance with another aspect of the invention the cradle roller has been shifted by 1mm forward thus reducing the front nip gauge from 50 mm to 49 mm. This in turn results in better control of the floating fibers. The drafting system in accordance with this invention provides for a better control of the short fibers in the drafting process, providing a better yarn quality. The invention also results in reduction of process waste by approximately 3%. In applications such as carded yarn, yarn imperfections may be reduced to about 30%. Thus the invention provides for better quality yarn with reduced process waste which in turn leads to significant financial savings, improving the competitiveness of a spinning mill. The invention also allows for the improvements in yarn and reduction in process waste with no significant additional cost. Thus, conventionally if short fiber content was high, combing of the carded sliver was a must, as the short fiber content resulted in a loss of control. However, the invention allows for better control of the short fibers and therefore the combed waste may be reduced or altogether eliminated depending on the quality required. The following experimental results support the aforementioned claims made by the applicant. The applicant's improvements and modifications have been referred to as the NIA drafting apparatus and the NIA apron. As can be seen from table 1 that the combing waste has been reduced by 3%. Yarn imperfections have also been reduced by approximately 30 % COMPARATIVE YARN DATA VIS A VIS KNITTED FABRIC DATA (COMBED YARN)_ (Table Removed) COMPARATIVE YARN DATA 60 COMBED (FOR GAS MERCERISING) (Table Removed) COMPARATIVE YARN DATA VIS A VIS KNITTED FABRIC DATA (COMBED YARN) (Table Removed) COMPARATIVE YARN DATA 60 COMBED (FOR GAS MERCERISING) (Table Removed) COMPARATIVE YARN DATA VIS A VIS KNITTED FABRIC DATA (CARDED YARN) (Table Removed) It will be readily appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention. We claim: 1.An improved cradle roller (14) for use in a drafting apparatus at the ring spinning frame employing aprons comprising: - a shaft(24) with a top end and a bottom end, said top end having a bearing mounted within a housing characterized in that the bottom end of the shaft being surrounded by a bearing (26) having a steel casing (28) mounted thereon, - said steel casing having a layer of rubber (30) on its outer surface said rubber layer being provided with a groove (32) at both ends to maintain contact pressure in the contact region, and provide a better control of the short fibers in the yarn. 2. An improved cradle roller as claimed in claim 1 wherein the diameter of the cradle roller is 25mm. 3. An improved cradle roller as claimed in claim 1 wherein the length of the groove is 5mm from both ends of the rubber layer. 4. An improved cradle roller as claimed in claim 1 wherein the depth of groove is 2mm. 5. An improved cradle roller as claimed in claim 1 wherein the effective contact width between the cradle roller and a middle bottom roller is 18.5mm. 6. An improved cradle roller(14) for use in a drafting apparatus at the ring spinning frame employing aprons as claimed in claim 1 wherein the apron is made of synthetic rubber comprising an outer surface having a rough surface finish and an inner surface, said inner surface being provided with grooves and a fine chord disposed within said apron. 7. An improved cradle roller(14) for use in a drafting apparatus at the ring spinning frame employing aprons as claimed in claim 6 wherein the diameter of the apron is 38mm. 8. An improved cradle roller(14) for use in a drafting apparatus at the ring spinning frame employing aprons as claimed in claim 6 wherein the width of the apron is 24mm 9. A cradle roller substantially as herein described with reference to and as illustrated by the accompanying drawings.

Documents:

1712-del-2004-abstract.pdf

1712-del-2004-claims.pdf

1712-del-2004-correspondence-others.pdf

1712-del-2004-correspondence-po.pdf

1712-del-2004-description (complete).pdf

1712-del-2004-drawings.pdf

1712-del-2004-form-1.pdf

1712-del-2004-form-19.pdf

1712-del-2004-form-2.pdf

1712-del-2004-form-3.pdf

1712-del-2004-form-5.pdf

1712-del-2004-gpa.pdf