Rollers for guiding elastic filaments in spinning machines

Abstract: The rollers have conical regions (8,9), extending from the edges of the yarn-guide groove (3) and inclined so as to converge towards the said groove (3) one of these conical surfaces (9) extending as far as an end edge (10) of the roller and the other (8) being connected to the base of the radially-projecting region (4), for establishing contact with the rollers of the drafting train. The conical regions (8,9) have the effect of automatically centring the yarn in the guide groove (3).

Description: The present invention relates to the technology of spinning with elastic filaments and, in particular, to rollers for guiding elastic filaments towards the delivery cylinders of a spinning machine. At the moment, various devices are known for guiding elastic filaments in spinning machines and the Applicant's own Spanish utility model 9201019, which discloses a head for carrying elastic-yarn guide-rollers having resilient O-rings fitted on their peripheries for establishing contact with the rollers of the drawing train, may be cited in particular. In the devices mentioned, and in other currently-known devices, there are various problems, particularly in guiding extremely fine yarns which may reach 22 decitex (that is to say, 10,000 metres of filament have a weight of 22 grammes). There are certain problems in spinning with the very fine yarns mentioned, owing to the ease with which the yarns can be displaced and come out of the guide. In fact, in currently-known rollers, when the operators handle the various elements of the machine, for example, to take out empty roving bobbins, to put in place full roving bobbins, etc., they may in many cases inadvertently touch the filament, removing it from the guide, so that the filament may be caught in an incorrect position, giving rise to a faulty yarn which will have to be discarded or which, if a fabric is to be manufactured on the basis thereof, may cause the manufactured fabric to be rejected with consequent economic losses. The present invention is intended to solve the above-mentioned problem, achieving good guiding of the yarns on the rollers with self-centering characteristics, that is to say that, if the yarn is deflected to a certain extent owing to inadvertent mechanical action thereon, the roller has means for the self-centering of the yarn, leading it back to the guide groove. To achieve its objects, the present invention provides for the formation of a guide roller in which the yarn-guide groove is connected by its edges, on one side, by means of a respective conical region, to the radially-projecting region or ridge carrying the O-ring for friction against the rollers of the drafting train and, on the other side, to a respective conical region extending along the entire useful length of the roller. If the yarn undergoes a certain displacement towards one side or the other, the respective conical regions, which converge towards the edges of the groove, thus lead the yarn back towards the latter, since the very tension of the yarn, acting transverse the axis of the roller, creates a force component which is directed in the direction of the taper and which will displace the deflected yarn back towards the guide groove. The roller characteristics mentioned are complemented by the elimination of steps or regions of any kind in which the yarn may become caught. In this respect, the present invention provides for the ridge for contact with the rollers of the drafting train to be formed integrally with the roller itself, that is, with the omission of the O-ring of elastomeric material which is normally used for contact with the drafting train, considerably increasing the efficiency of the roller in the sense of preventing deflection of the yarn. For a better understanding, some drawings illustrating a preferred embodiment of the present invention are appended by way of non-limiting example. Figure 1 shows schematically a longitudinal section through a roller formed in accordance with the present invention, showing schematically the self-centering effect. Figure 2 is an elevational view of a roller according to the present invention in its position of contact with a roller of the drafting train. Figure 3 is a partially-sectioned elevational view of an assembly of two rollers mounted on the same shaft and working in combination with the drafting train. Figures 4, 5 and 6 are sections taken in the planes indicated through a roller formed in accordance with the present invention. Figures 7 and 8 are side and front elevational views of the roller, respectively. As shown in the drawings, the present invention provides for the formation of rollers for guiding elastic filaments during the spinning operation, the rollers having characteristics for self-centering the yarn and preferably comprising a unitary body 1 provided with a central mounting hole 2 and having a yarn-guide groove 3 defined by sides 5 and 6 which define the base 7 which is to receive the yarn. In accordance with the present invention, the groove is extended at the edges of its sides by respective conical regions having different tapers and indicated 8 and 9, the said cones converging towards the groove 7 which is the region corresponding to the narrowest portions of both cones. The conical region 9 extends practically for the entire length between the groove 3 and an end edge 10 of the roller, whereas the conical region 8 extends as far as the ridge 4 which is intended to establish contact with the corresponding roller of the drafting train which is indicated 11 in Figure 2. The ridge or radially projecting region 4 has at least one lateral face 24 which is inclined towards the groove 3 and a cylindrical outer region 25 concentric with the axis of symmetry of the roller. The other face 26 which delimits the projecting region 4 may also have a certain inclination towards the end of the roller. This arrangement eliminates intermediate steps or regions of any kind in which the yarn may be caught. In fact, as shown in Figure 1, if a yarn 12 is deflected sideways from the base 7 of the groove by a transverse force, the very tension of the yarn produces a force F1 which, when it acts on the inclined surface 8, is resolved into a force F2 perpendicular to the said surface and a force F3 acting parallel to the surface itself and in a direction such as to compel the yarn 12 to go back to the base 7 of the groove in a self-centering action which prevents the yarn from coming out. Thus, as shown in Figure 2, to whatever position the yarn may be deflected sideways, for example, the positions indicated by the broken lines 13 and 14, the forces according to the vectors 15 and 16 will tend to return the yarn 12 to the base of the groove so that it is well centered again. In a variant, the roller in accordance with the present invention may be formed as shown in Figures 4 to 8 in which the roller 17 has conical regions 18 and 19 adjacent the guide groove 20 and the ridge for contact with the rollers of the drafting train is formed by an elastomer O-ring 21. In this version, apart from the conical surface 18 linking the edge of the groove and the seat of the O-ring 21, the roller will have a second outer inclined plane 22 joining the front face 23 to the seat of the O-ring 21. In any case, it is advisable for the planes 18 and 22 to be inclined at a small angle to the surface of the O-ring 21 to avoid regions in which the yarns may be caught.

Claims: Rollers for guiding elastic filaments in spinning machines, of the type comprising a unitary body (1) which can be fitted on a carrying shaft and which has a peripheral yarn-guide groove (3) as well as a radially-projecting lateral region for establishing tangential contact with the rollers of the drafting train, characterized by respective conical regions (8, 9) extending from the edges of the yarn-guide groove, and inclined so as to converge towards the groove (7), one of these conical surfaces extending as far as an end edge of the roller and the other being connected to the base of the radially-projecting region (4) for establishing contact with the rollers of the drafting train. Rollers for guiding elastic filaments in spinning machines according to Claim 1, characterized in that the radially-projecting region (4) for contact with the rollers of the drafting train forms a single piece with the roller itself and at least one of its lateral faces is inclined towards the yarn-guide groove. Rollers for guiding elastic filaments in spinning machines according to Claim 2, characterized in that the radially-projecting region (4) for establishing contact with a roller of the drafting train has an externally cylindrical shape concentric with the axis of symmetry of the roller. Rollers for guiding elastic filaments in spinning machines according to Claim 1, characterized in that the radially-projecting region (4) for contact with the rollers of the drafting train has a contact 0-ring delimited by respective faces, of which one is inclined towards the yarn-guide groove and the other is inclined towards the corresponding end of the roller. Rollers for guiding elastic filaments in spinning machines according to Claim 4, characterized in that the lateral faces delimiting the region in which the O-ring is fitted are inclined at small angle to the outer surface of the latter.

Inventors: PRAT JOSEP FIGULS, PRAT, JOSEP FIGULS
Applicants: PINTER S A, PINTER, S.A.
Application year: 1997
Main classification: D01H13
IPC codes: B65H57, D01H13