Method for parallelising fibres in a drawing system and apparatus for its implementation

Abstract

 The method comprises exerting a transverse pressing action on one or more successive points of the sliver (7) between the line of entry rollers (1) and the line of intermediate rollers (2) or rollers carrying "bags", obliging the sliver (7) to follow a path in the shape of an open "V" or similar which vary from the rectilinear path customarily followed.

Description

[0001] The present invention relates to a method for improving the parallelising of fibres in the drawing systems of spinning machines, and likewise relates to an apparatus for the implementation of said method.

[0002] As is known, one of the problems that must be solved in spinning is that of parallelising of the fibres, so that the yarn has the fibres correctly aligned, along the axis of the yarn itself, avoiding fibres that protrude and reduce the quality of the yarn.

[0003] Conventionally, the operation of drawing the yarns, starting from the slivers fed to the continuous spinning machines, is carried out by means of so-called drawing systems, which have adopted the universal form of dividing the total drawing into a first zone or preliminary zone and another, main zone, the total drawing being the product of the drawing ratios of one and the other of said zones.

[0004] Preliminary drawing is carried out between the feed roller or third line roller, and the "bag" roller or second line roller, with very reduced values, customarily defined by drawing ratios between the respective linear velocities ranging between 1.05 and 2.5. The main drawing is carried out between the rollers of the second line or "bag" rollers and the delivery rollers or first line rollers, with a very high drawing ratio, which may have a value of 50 or more. In conventional drawing, the sliver is drawn from the feed roller to the second roller or "bag" line, along a line tangential to both rollers.

[0005] In spite of the customary practice of this drawing method and of the improvements introduced into it over the years, the quality of the yarns still leaves quite enough to be desired, having multiple effects in a greater or lesser proportion according to the types, which define the quality of the yarn obtained and which in practice are evaluated by determination of values of standardised parameters with apparatus and devices well known in this industry.

[0006] The present inventor has carried out extensive investigations in order to obtain improvements in the quality of the yarns after drawing, having arrived at the present invention.

[0007] The present invention is characterised by the simultaneous application to the sliver, between the third line of rollers and the second line of rollers of a conventional drawing system, of a transverse tension which causes the rectilinear path customarily followed to be varied by a new path, in the shape of an open V or similar, with the application of a simultaneous action of parallelising of the fibres which form the sliver.

[0008] In a preferred version, the action of transverse pressing and deformation of the rectilinear path of the sliver will be carried out so that the path assumes a single open V-shape, that is to say, in the form of an obtuse angle, but it will be understood that a similar effect could be obtained by the application of deformation at various successive obtuse angles, right angles or acute angles, depending on the spinning characteristics.

[0009] The device for the implementation of the present method basically comprises one or more deflectors or bars arranged transversely with respect to the sliver between the third and second lines of rollers of the drawing system, said bar or bars having areas of contact with the sliver that are formed by a curved surface, having in the area of contact with the sliver a very smooth finish capable of producing a reduced effect of friction on the fibres of the sliver and, at the same time, parallelising the fibres, preferably obtained by means of the arrangement of fine grooving in the area of contact with the sliver, according to parallel grooves extending in the direction of movement of said sliver.

[0010] The device will have means for micrometric variation of the height of the bar or pressure members over the sliver.

[0011] The pressure members over the sliver will preferably consist of bars arranged transversely with respect to the sliver, preferably consisting of tubular members of substantially oval shape, provided with very controlled finish characteristics and/or grooves parallel to one another in the areas of contact with the sliver.

[0012] The area of contact of the bar with the sliver should be very polished and of a material which does not produce static electricity. As has been indicated, for some materials the parallelising results are improved if in the area of contact some very fine, small grooves are provided which apparently act like a comb, and which will preferably be rounded, for example, with a width of the order of 0.5 mm.

[0013] The device carrying the bars indicated will have means for varying the height of the bar with respect to the sliver which, after the V-shaped deformation produced on the sliver, will determine the effective height separation between the tangent to the rollers of the third and second lines and the vertex or point of major deformation at which the sliver will have arrived, after being subjected to the deforming action of the bar. Equally, the distance between the tangent point between the sliver and the third line of rollers and the tangent point of the deflecting bar will likewise be important, both values indicated needing to be adjusted in order to obtain the optimum efficiency, according to the variable characteristics of the slivers to be processed.

[0014] It has been found in practice that, on implementing the method of the present invention, in the slivers in the drawing phase in the conditions indicated, there is a systematic and repeatable improvement in the quality of the yarn obtained, which exhibits better characteristics in any of the parameters which define in a standard manner the quality of the yarn, and which refer especially to the defects of finish of the yarn and to its strength.

[0015] For better understanding, some drawings of a preferred embodiment of the present invention are appended by way of non-limiting example.

Figure 1 shows diagrammatically in section a drawing system in which the present invention is incorporated.

Figure 2 shows a diagrammatic plan view of the drawing system of Figure 1.

Figure 3 shows a perspective view of the members of the drawing system modified according to the present invention.

Figures 4 to 8 show details of a variant of the support and adjustment device of the bars for the implementation of the present invention.

Figure 9 shows a view in section according to the section plane indicated.

Figure 10 shows a view in front elevation of one of the deflecting bars according to the present invention.

Figure 11 shows a detail of grooving of the deflecting bars.

Figure 12 shows a perspective view of the device of the invention.

[0016] As will be observed in the figures, a conventional type of drawing system comprises three successive lines of pairs of rollers which have been indicated in the figures by the numbers 1, 2, and 3, the first of these being the feed rollers or third line rollers, the second are those termed second line or "bag" rollers owing to the "bags" 4 and 5 associated with said second line of rollers, and a third line of rollers 3 which is that which achieves the final drawing.

[0017] As will be observed in Figure 2, the incoming sliver 6 is reduced between the lines of rollers 1 and 2, giving rise to a sliver of lesser width 7 which is reduced once more between the second and first lines, giving rise, together with the twisting action, to the yarn 8.

[0018] As has been indicated, the drawing ratio between the rollers 1 and 2 varies customarily between 1.05 and 2.5, and the drawing ratio between the rollers 2 and 3 reaches very high values, of the order of 50.

[0019] The method of the present invention is based on causing the sliver 7, in an intermediate position between the third and second lines of rollers, to form a path substantially in the shape of one or more open Vs, that is to say, with an obtuse angle, by means of the application of a transverse pressure adapted to the characteristics of the sliver, said transverse deflecting action being optionally simultaneous with a parallelising action by means of grooving of the area of contact.

[0020] Although the drawings show a single V-shaped area for the transverse deformation of the sliver, it would also be possible to arrange more than one angular deformation area, so that instead of one obtuse angle, two or more could be provided in succession, in which case the direction of the vertices 9 would naturally be inverted along the path of the sliver.

[0021] The apparatus intended to carry out the method of the invention will comprise a pressure area over the sliver 7 having a curved shape, for example the curved shape of an arc of a circle, preferably incorporated in a bar 10 of the type shown by way of example in the figures.

[0022] However, it should be understood that the precise shape of the pressure piece which acts on the sliver may vary within wide limits, taking into account above all the different characteristics of the slivers to be processed.

[0023] The area of contact with the sliver 7 will customarily be very polished and, optionally, may be provided with a plurality of grooves 11, parallel to one another, which occupy the area tangent to the sliver and areas immediate thereto, preferably having a curved shape, for example, as shown in Figure 11, in which will be observed the grooves 11 with a curved base separated by crests 12 of the same shape. Also, at this point, it should be pointed out that the existence or otherwise of said grooves and the precise shape thereof will be variable according to the spinning characteristics.

[0024] The apparatus of the present invention will have means for supporting the bar 10 or similar member carrying the curved area of contact with the sliver, and will preferably be associated with an arm 13 of variable characteristics, single or multiple, and provided with means 14 for its micrometric adjustment on a graduated scale 15 to permit precise determination of the position of the bar 10, determining the values h and x which determine the position of the tangent point of the deflector member or bar on the sliver 7 with respect to the tangent plane between the rollers of the third and second lines of the drawing system, and its height with respect to said line.

[0025] The specific structure of the support of the deflectors or bars will vary within wide limits to permit the production of concrete embodiments adaptable to the different types of spinning machine existing on the market so that these can be adapted so as to be able to work with the method of the present invention.

[0026] Figures 3 to 8 show a variant in which two arms 16 and 17 carry a bar 18 which passes through them, giving rise to two work areas 19 and 20, moving on guides of the type 21 and 22 fixed to the support 23 that can be fixedly coupled to the drawing system, making it possible to obtain easy height adjustment of the bars 10 with respect to a graduated scale 24 provided on the guides mentioned. As may be observed in Figure 10, the work areas 19 and 20 may include respective grooves of the type which has been explained.

[0027] The angular arrangement of the bars with respect to the sliver may likewise be variable, a version having been shown in the figures in which the plane of symmetry of the bar forms an acute angle with the axis of displacement of the support (Figure 1). However, said angle may also be variable within wide limits.

[0028] The results of tests carried out with the application of the method and apparatus of the present invention will be indicated hereinafter.

[0029] The laboratory tests were carried out with a USTER apparatus and the USTER standardised characteristic values of quality of the yarn CV and U, customarily used in this field, were determined, and also the fine points, coarse points, local defects or neps and ratio of appearance DR.

[0030] Table 1 shows the result of the tests with metric No. 100 combed cotton and with total drawing of 30.

[0031] As may be seen, the reduction of defects is very significant in all the divisions relating to the quality of the yarn which depend typically on the drawing and twisting process, especially CV (coefficient of variation), U (USTER standardisation), fine points, coarse points and ratio of appearance DR. The slightly higher value for neps is interpreted as an effect due basically to defects of the sliver or very short fibres on which the drawing operation logically has a very reduced influence.

[0032] Table 2 shows the results of the laboratory tests for fluffiness, carried out on metric No. 100 combed cotton yarns with total drawing of 30. N1 to N10 show, in order, the number of strands of 1, 2, 3..10 mm length per 400 metres of yarn, and at S3 the total quantity of strands having a length of 3 mm or more in the same length of 400 metres.

Table 1.

CV values (%), U (%), fine points, coarse points, neps and DR (%) for conventional yarn and for yarn manufactured according to the invention (Preliminary drawing): 1.21. Total drawing: 30. 100 Nm (metric No.) combed cotton
REFERENCE	CV (%)	U (%)	Fine points (-50%)	Coarse points (+50%)	Neps (+200%)	DR (%) (1.37 m, ± 5%)
Conventional yarn	19.1	15.1	283	270	80	25.3
Yarn according invention	15.1	11.7	14	139	87	13.3

Table 2.

Fluffiness of conventional yarn and of yarn manufactured according to the invention (Preliminary drawing: 1.21. Total drawing: 30. 100 Nm combed cotton)
	REFERENCE
	Conventional yarn	Yarn according invention
N1	38230	25313
N2	4473	2494
N3	2136	1099
N4	1139	926
N6	184	112
N8	20	16
N10	2	3
S3	3481	2156

[0033] The excellent results obtained will be observed, especially in the more significant values N2-N6.

[0034] It will be clearly observed, therefore, that the application of the present invention in drawing systems makes it possible to obtain significant improvements in the quality of yarn obtained.

[0035] As will be understood, the invention has been described with reference to concrete embodiments which are solely exemplary in nature. It should be understood, however, that the invention will include all those variants which may be applied by experts in the field, taking advantage of the material which is disclosed in the present patent application, and that said variations will be included within the scope of the patent provided that they do not depart from the scope of protection of the appended claims.

Claims

1. A method for parallelising the fibres in a drawing system of the type which has three lines of pairs of rollers, that is, a pair of feed rollers, an intermediate pair of drawing rollers and a pair of discharge rollers, characterised in that a transverse pressure action is exerted on one or more successive points of the sliver between the line of entry rollers and the line of intermediate rollers or rollers bearing "bags", obliging the sliver to follow a path with one or more areas in the form of an angle with sides adjacent to the points of transverse pressing on the sliver.

2. A method according to claim 1, characterised in that the threads follow a curved path in the area in which transverse pressure is exerted thereon.

3. A method according to claim 1, characterised in that a longitudinal parallelising action is exerted on the sliver simultaneously with the transverse pressing action.

4. An apparatus for the implementation of the method, according to claims 1 to 3, characterised in that it comprises a support that can be coupled to the frame of a conventional drawing system, provided with means for adjustable fixing of the pressure medium over the sliver, provided with means for micrometric variation of the tangent point of the pressure means with respect to the sliver.

5. An apparatus according to claim 4, characterised in that the pressure means consists of one or more bars provided with curved and polished areas for contact with the sliver in the area of transverse pressure.

6. An apparatus according to claims 4 and 5, characterised by the arrangement on the deflector bars of a plurality of parallel grooves in the area of contact with the slivers, in order to improve the parallelising of the fibres.

7. An apparatus according to claims 4 and 5, characterised in that the bars are coupled on the support forming an adjustable angle with respect to the axis of longitudinal displacement of the support.

Drawing