Title of Invention

CYLINDRICAL CHEESE AND METHOD FOR FORMING THE WOUND PACKAGE OF A CYLINDRICAL CHEESE

Abstract

Cylindrical Cheese and Method for Forming the Wound Package of a Cylindrical Cheese The method is used for forming the wound package of cylindrical cheeses on rotor spinning machines, wherein the crossing angle a is designed to be less than 28° in a central zone of the bobbin traverse, and a crossing angle aR, which is increased in respect to the central zone, is created in the zones located toward the ends of the wound package. The cylindrical cheeses produced in accordance with the invention are distinguished by great running lengths, solid structure, good density distribution, as well as excellent draw-off properties. (Fig. 2)

Full Text

THE PATENTS ACT, .1970 (39 of 1970) CYLINDRICAL CHEESE AND METHOD FOR FORMING THE WOUND PACKAGE OF A CYLINDRICAL CHEESE W. SCHLAFHORST AG & CO 4106.1, MONCHENGLADBACH of BLUMENBERGER STRASSE 143-145, D-GERMANY, GERMAN Company The following specification particularly describes the nature of the invention and the manner in which it is to he performed : - Specification Cylindrical Cheese and Method for Forming the Wound Package of a Cylindrical Cheese The invention relates to a cylindrical cheese and a method for forming the wound package of a cylindrical cheese with a yarn guide device in accordance with the preamble of claims 1 and 7. Yarn produced on rotor spinning frames differs in its bobbin building and pull-off behavior from ring-spun yarn. The rotor yarn is less napped than the ring-spun yarn and therefore in easier to unwind (greater ease of lift-off), but has a greater curling tendency than the ring-spun yarn, so that in the edge areas of the cheese the wound-up yarn is pushed away outward by the yarn layers located on top. Because of this, a cheese can be formed which exceeds the normal bobbin traverse of, for example, 150 mm and grows up to a width of 170 to 180 mm. In such a case the desired bobbin buildup with level front faces is no longer possible. Such appearances occur in connection with yarns made of natural fibers, such as cotton, in particular with coarse yarns, and are all the more marked the coarser the yarn is. Problems at the front faces of wound packages can already appear in the pre-stage of yarn production with wound-up fiber slubbing or roving yarn. USP 954,344 describes that in connection with slubbings or rovings, which are not twisted at all or only slightly, bulges occur in the its build-up at the front faces. This disadvantageous effect occurs there if the winding angle is greater than 32°, which is customary in the prior art. This is assisted by the soft and loose structure of the fiber strands. Such bulges can considerably impair the further processing of the wound packages. In accordance with USP 954,344 it is intended to prevent the bulging by increasing the winding angle in the edge areas of the wound package, while it remains the same in the rest. 2 If cheese winding is performed at high yarn speeds, it is possible in connection with medium and coarse yarns that, because of the mass inertia of the yarn, the yarn moves past the bobbin edge at the reversing points of the traverse and a so-called skipped yarn error is created. This fault leads to yarn breaks and hampers the further processing of the yarn. The possibility of the occurrence of such errors is considerably'affected by the crossing angle a. Therefore the selection of the appropriate crossing angle is of great importance when producing cheeses. While in the course of producing a cheese with "random cross winding" the yarn crossing angle remains constant over the entire bobbin travel, the yarn crossing angle changes in a cheese with "precision winding" in that it is reduced when the cheese diameter increases. The advantages of precision winding rest, inter alia, in that, at the same bobbin volume, a cheese with precision winding has a greater running length in comparison with a cheese with random cross winding. However, the crossing angle, which is reduced with increasing cheese diameter, limits the permissible maximum diameter when producing precision bobbins made of .staple fiber yarns since, in particular'in connection with staple fiber yarns, it is not possible to perform winding at arbitrarily narrow crossing angles in order to avoid the defects occurring at the edges. For this reason, and as described, for example, in DE 100 15 933 Al, which defines the species, crossing angles of less than 28° should be avoided in rotor spinning. Therefore the precision winding can only be used to a limited extent, in particular when winding staple fiber yanna In a third type of winding, the "step precision winding", a crossing angle which remains approximately the same is the goal. In actual use, the above described density problems, or problems 3 with the stability of the bobbin edge, are merely somewhat reduced by means of the step precision winding, but not solved. With conical cheeses which are driven by circumferential friction by a roller, it is necessary to let the drive be effective only within a predetermined'area of a narrow friction zone, or of the friction zone of the cheese. Since the length of the bobbin circumference, viewed via the bobbin axis, differs, the number of revolutions of the cheese begins to fluctuate and becomes uncontrollable if the conical cheese to be wound comes into contact with, the portions of the roller-shaped drive mechanism located to the left and right of the predetermined friction zone as the bobbin diameter grows. To prevent this, the yarn crossing angle is reduced in comparison with the yarn crossing angle outside of the friction zone in an area limited to the friction zone of a conical cheese represented in DE-AS 26 32 014, or in the parallel US Letters Patent 4,266,734. By means of this the compressive strength .of the wound package is slightly increased in the winding zone. However, the reason for forming a drive zone with increased specific pressure of the bobbin resting on the drive roller by changing the yarn crossing angle is only provided by the different circumferential bobbin length in case of conical cheeses. New machine technology,, in particular in weaving, such as air nozzle power looms, for example, make greater demands on the pull-off properties of the yarn. These requirements cannot be met, or only insufficiently met, by means of the known bobbin embodiments. The object oi. the invention 1;; based on dealing a cylindrical cheese which is improved in comparison with known cylindrical cheeses, and a method for producing it on rotor spinning frames, in particular when producing coarse yarns. 4 This object is attained by a method in accordance with claim 1, and a cylindrical cheese in accordance with claim 7. The dependent claim: are directed to advantageous embodiments of the invention. The invention proceeds from the knowledge that it is possible by means of crossing angles in the edge area of the cheese, which are larger then the crossing angles in the central part, to clearly reduce the crossing angle in the remaining wider central portion in comparison with customary crossing angles, without having to accept the known disadvantages occurring when the crossing angle is reduced over the entire winding width. In this case the reduction of the crossing angle can be pushed substantially far without resulting in an impermissible hardening of the cheese. The invention leads to an improved pull-off of the yarn from the cylindrical cheese. The yarn pull-off is quieter, counteracts the formation of loops, as well as yarn entanglements, and thus permits higher yarn pull-off speeds. The bobbin buildup, in particular at the front faces of the cylindrical cheese, is improved. With the same bobbin diameter, the running length of the yarn is shown to be clearly increased in comparison with a conventional cylindrical cheese. The embodiment of the crossing angle a in accordance with one of claims 2, 3 and 4, as well as 8, 9 and 10, leads to an increase of the wound-on yarn length, while an excellent stability of the cylindrical wound package can be maintained, along with high density. The crossing angle a of the central zone advantageously, continuously increases from the crossing angle aM of the central zone to the crossing angle aR of the edge zone. The edge zones can be of such size that they occupy no more than respectively 15% of the entire winding width BWG. 5 A reduction'of the bobbin contact pressure with increasing bobbin diameter respectively performed in accordance with claim 5, as well as a reduction of the yarn tension in accordance with claim 6, assures the suppression of an undesired high yarn tension in connection with crossing angles a in accordance with the invention which are less than 28°. The bobbin contact pressure is known to be composed of the weight of the bobbin and the weight of the bobbin.frame, as well as the force resulting from a torque provided, for example, by a torque sensor. In this case the bobbin compact pressure can be reduced in such a way that not only is the bobbin weight compensated, but a relief beyond that occurs. If a yarn guide, for example a belt yarn guide, already exists at a winding head for generating the traversing movement, whose speed can be controlled separately from the number of bobbin revolutions, the method of the invention for producing a cylindrical cheese in accordance with the invention can be executed in a simple way without any additional structural outlay and without exchanging yarn guide elements in a simple way by the appropriate arrangement, or programming of the control. The inventi.on permits the winding-up of even coarse yarns with relatively narrow crossing angles. For example, processing of cotton yarn of a metric count of 2 0 at a crossing angle a of 25° is still possible, along with the good pull-off properties and large running lengths. Improved pull-off properties lead to the reduction of down times because of the lowering of the number of yarns breaks in the course of the further processing of the yarn bobbins, By means of the running length, which increases along with the reduction of the crossing angle, it is possible to achieve the winding of an amount of yarn increased by approximately 15% to 25% on a cylindrical cheese in accordance with the invention when compared with a conventional cylindrical cheese of the same bobbin diameter. This leads to a clear 6 reduction in the number of cheeses of a batch. Not only are the down times for bobbin changes reduced at the spinning head because of this, but also the conveying outlay and the conveying volume for conveying the bobbins are reduced. It is possible to reduce the layout for handling the cheeses in the course of the subsequent yarn treatment processes. The invention improves productivity and makes it possible to lower costs, and in this way to increase efficiency of yarn production and yarn processing. Further details of the invention will be explained by means of the drawings. Shown are in: Fig. 1, a lateral view of a spinning head for executing the method in accordance with the invention in a simplified schematic representation, Fig. 2, the basic representation of a cylindrical cheese in accordance with the invention, Fig. 3, the course of the crossing angle a over a traverse. represented simplified in the form of a curve. A winding device 1 at a spinning head of a rotor spinning frame producing cylindrical cheeses is represented in Fig. 1. The winding device 1 has a roller 2, which drives the cylindrical cheese 3 by means of friction. The roller 2 rotates in the direction of the arrow 4. The cheese 3 is held in a pivotable creel 5 and rests on the roller 2. In the course of this the roller 2 is changed with a contact pressure. The yarn 6 is pulled off at a constant yarn speed by the spinning box 10 of the spinning head in the direction of the arrow 7 by means of pull-off rollers 8, 9, which work together as a pair of rollers, and is wound up as the wound package 12 of the cheese 3 by means of a back-and-forth moving yarn guide 11. The yarn guide 11 is a part of the traversing device 13, which is connected by means of an 7 operative connection 14 with the motor 15 and is driven by the latter. The roller 2 is driven via the shaft 16 by a motor 17. The motor 15, as well as the motor 17, are controlled by a microprocessor 18, wherein the crossing angle a of the cylindrical cheese 3 can be controlled during the respective bobbin traverse as a function of the position of the yarn guide 11. The cylindrical cheese 3 represented in Fig. 2 shows a wound package 12, which was wound in accordance with the invention on the bobbin case 19. In the respective edge zones 20, 21, the wound package 12 has a cross winding with a crossing angle and in the central zone 2 2 a cross winding with a crossing angle In the exemplary embodiment of Fig. 2, is 35°, and is 25°. The width of the zone 22, as well as that of the edge zones 20, 21, are each marked by a dashed line. The cylindrical wound package 12 is shown in a simplified basic representation, wherein the respective course of the wound-on yarn 6 is only partially indicated, but makes it possible to detect crossing angles of different size. In the exemplary embodiment, the width of the cheese 3 from the left bobbin edge 23 to the right bobbin edge 24 is 150 mm. .The width corresponds to one traverse of the yarn guide 11. Because of the inertial forces, which can become effective at the high speeds of the traversing movement even with the relatively low mass of the yarn 6, in particular with coarse yarn, and which'occur because of the movement reversal of the back-and-forth moving yarn guide 11, the change of a value of the crossing angle a to a different value does not take place abruptly, as Thus, the representation in Fig. 3 comes closer to the actual embodiment of the crossing angles of the cheese 3, or the course of the yarn on the surfaces, than the representation in Fig. 2. Fig. 3 shows the course of the size of the crossing angle a, represented in the form of a curve 31, over the winding width cheese 3, wherein the values represent the traverse of the yarn guide 11 in Fig. 2 from left to right {traverse of the yarn guide 11 during the forth portion of the back-and-forth movement) . At the left reversing point of the yarn guide 11, or at the left bobbin edge 23, the crossing angle a passes through the zero point, and in the left edge zone 2 0 it reaches the value of . From = 35°, the value decreases after a transition area down to . The value of maintained constant in the central zone 2 2. At the right side of the cheese 3, the value of rises again to in the right edge zone 21, and thereafter again passes through the zero point at the right reversing point of the yarn guide 11, or at the right bobbin edge 24. The width of the central zone 22, in which the crossing angle a has the value = 25°, takes up the preponderant portion of the winding width The course of the crossing angle a in the course of the traverse of the yarn guide 11. in the return movement toward the left is indicated by dashed lines in Fig. 3. The setting of the crossing angle a is performed in a manner known per se, and therefore not explained here, by controlling the rotational speed of the cheese 3 and the speed of the traversing movement of the yarn guide 11 in the course of the traverse . The.cylindrical cheese 3, which has been produced with a crossing angle in the edge.zones 20, 21, has stable bobbin edges 23, 24 without an impermissibly high contact pressure being exerted. Bulges at the front face of the cheese 3 angle a. = 25° in the zone 22 located between the edge zones 22 makes possible an increased running length with a stable wound package and with the same production diameter of the cheese 3, for example 300 mm, which therefore contains 15% to 25% more yarn than conventional bobbins of the same diameter. The pull-off behavior of the cylindrical cheese 3 has been improved by quiet yarn running and the suppression of the formation of loops and yarn entanglements. The invention is not limited to the exemplary embodiments represented. For example, the yarn guide can be alternatively embodied as a belt yarn guide or as a grooved roller. The crossing angle & of the cylindrical cheese of the invention can advantageously assume alternative values in the range of 30° to 40° in the edge zones 20, 21, and in the central zone 22 in the range of 15° to 28°. -10 - 1. A. method for forming the wound package of a cylindrical cheese, wherein the crossing angle a is changed in the course of the bobbin travel, characterized in that the yarn guide is provided in such a way that in a central zone of the bobbin traverse a crossing angle aM of less than 28°, as well as .greater than 15°, is executed, and that in the edge zones located toward the ends of the wound package a crossing angle aM is generated, which is increased in respect to the central zone (22). 2. The method in accordance with claim 1, characterized in that the crossing angle aM in the central zone (22) is generated with a value between 20° and 26°. 3. The method in accordance with claim 1 or 2, characterxzed in that in the central zone (22) the crossing angle aM is made at least 8° smaller than the maximum crossing angle aR in the edge zone (20, 21) . 4. The method in accordance with one of the preceding claims, characterized in that the central zone (22) takes up more than 50% of the entire winding width BWG Li. The method in accordance with one oJ. the preceding claims, characterized in that the bobbin contact pressure is reduced with an increasing bobbin diameter. 6. • The method in accordance with one of the preceding claims, characterized in that the yarn tension is.reduced with an increasing bobbin diameter. 7.. A cheese with a cylindrical wound package made of rotor yarn, characterized in that within each yarn layer the crossing angle a in a central zone (22) of the bobbin traverse is designed to be less than 28°, as well as greater than 15°, and a crossing angle aR, which is increased in respect to the central zone (22), is only provided in the edge zone located toward the ends of the wound package. 8. The cheese in accordance with claim 7, characterized in that in the central zone (22) the crossing angle aM has a value of between 20° and 26°. 9. The cheese in accordance with one of claims 7 or 8, characterized in that in the central zone (22) the crossing angle o-M is at least 8° smaller than the maximum crossing angle a^ in the edge zones (20, 21). 10. The cheese in accordance with one of claims 7 to 9, characterized in that the at least one zone (22) with a reduced crossing angle aM constitutes more than 50% of the entire winding width BWG Dated this i61h day of December, 2O02.

Documents:

1127-mum-2002-absrtact(02-07-2004).doc

1127-mum-2002-abstract(02-07-2004).pdf

1127-mum-2002-abstract.doc

1127-mum-2002-abstract.pdf

1127-mum-2002-cancelled pages(02-07-2004).pdf

1127-mum-2002-claims(granted)-(02-07-2004).doc

1127-mum-2002-claims(granted)-(02-07-2004).pdf

1127-mum-2002-claims.doc

1127-mum-2002-clamis.pdf

1127-mum-2002-correspondence(05-07-2004).pdf

1127-MUM-2002-CORRESPONDENCE(12-12-2011).pdf

1127-mum-2002-correspondence(ipo)-(09-11-2004).pdf

1127-mum-2002-correspondence.pdf

1127-mum-2002-correspondence[ipo].pdf

1127-mum-2002-declaration.pdf

1127-mum-2002-description(granted).doc

1127-mum-2002-description[granted].pdf

1127-mum-2002-drawing.pdf

1127-mum-2002-form 1(02-07-2004).pdf

1127-mum-2002-form 1(17-12-2002).pdf

1127-mum-2002-form 1.pdf

1127-mum-2002-form 13(02-06-2004).pdf

1127-mum-2002-form 13[2-6-2004].pdf

1127-mum-2002-form 13[2-jul-2004].pdf

1127-mum-2002-form 19(15-12-2003).pdf

1127-mum-2002-form 19.pdf

1127-mum-2002-form 2(granted)-(02-07-2004).doc

1127-mum-2002-form 2(granted)-(02-07-2004).pdf

1127-mum-2002-form 2(granted).doc

1127-mum-2002-form 2[granted].pdf

1127-mum-2002-form 2[title page].pdf

1127-mum-2002-form 3(02-07-2004).pdf

1127-mum-2002-form 3(05-07-2004).pdf

1127-mum-2002-form 3.pdf

1127-mum-2002-form 5(05-07-2004).pdf

1127-mum-2002-form 5.pdf

1127-mum-2002-other documents(17-12-2002).pdf

1127-mum-2002-power of attorney(02-07-2004).pdf

1127-mum-2002-power of attorney(22-01-2003).pdf

1127-mum-2002-power of attorney.pdf

1127-mum-2002-power of attorney[2-jul-2004].pdf

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