FRICTION OPEN-END SPINNING APPARATUS

Abstract: A friction spinning apparatus comprises two rollers (1, 2) in closely spaced parallel arrangement which define between them a yarn formation zone at an elon­ gate gap along the rollers and a feed duct (41) which extends into the gap so as to feed fibres directly into the gap in such a manner that they can fall directly onto the yarn. The feed duct (41′) is biassed slightly toward the roller (1) which turns into the gap so as to increase the proportion of fibres joining the yarn (419) at the junction with that roller.

Description: This invention relates to apparatus for open-end spinning yarn and particularly to apparatus of the type known as friction spinning. Apparatus of this type has been proposed previously in many publications. One specific example is shown in British Published Application GB-A-2 042 599 (Platt Saco Lowell) and comprises two rotatable bodies each providing a surface and arranged such that the surfaces define between them an elongate gap which narrows towards a line of closest approach of the surfaces, means for rotating one of the bodies in a direction such that its surface moves into the gap and the other body such that its surface moves out of the gap to twist the fibres in the gap to form a yarn, means for withdrawing the yarn along the gap, and fibre feed duct arranged to feed fibres substantially directly into the gap such that some fibres can fall directly on to the yarn. Apparatus of this type has also be disclosed in a number of patent specifications by Dr. Ernst Fehrer for example published British Application GB-A-2 022 152 and have achieved some commercial success. However improvement in yarn quality in an ongoing and fundamental requirement to ensure the widest commercial acceptability of the yarns from the apparatus. In these prior apparatus, the fibres are fed substantially symmetrically on to the two bodies or rollers and this has always been an accepted principle in apparatus of this type to maintain the symmetry of the system. In an alternative line of development arising from British Patent GB-A-1 231 198 (TMM) and followed up in Fig. 2 of U.S. patent US-A-4 130 983 (Barmag) and for example British Published Application GB-A-2 011 956 (VUB) the fibres are fed directly on to the one of the surfaces which turns into the gap in a manner which prevents fibres falling directly onto the yarn and such that the fibres are deposited on the surface first and carried into the gap on the surface. For example, Figures 2 and 2a of U.S. Patent US-A-4,130,983 (Barmag) show the fibres being deflected laterally at the discharge end of the feed duct so as to impinge on the surface of the associated foraminous drum substantially radially of the drum. "Figure 6a of U.S. Patent US-A-4,130,983 shows a perspective view of a feed duct which directs fibres between the suction drums, but feed the fibres against one of the two drums, as mentioned at column 9 lines 52 to 55. The fibres, will then be carried, on the surface of that drum, into the nip to contact the yarn." This arrangement has been considered unsatisfatory because it does not allow the proper orientation of the fibres achieved in the feed duct to be communicated directly into the yarn structure and hence workers have turned away from this arrangement to the symmetrical arrangement outlined above and it has effectively been abandoned. The objective of the present invention is therefore, arising from the presently accepted symmetrical feed arrangement outlined above, in which the fibres are directed substantially parallel to the direction of movement which the surface moving into the nip has at the line of closest approach, to obtain an improvement in yarn quality by a modification to that arrangement. Accordingly the invention is characterized in that the fibre feed duct extends to within 10 mm of the yarn formation portion and is biased to one side of the central plane of the nip so as to tend to direct more of the fibres towards the perforated surface of the first body which moves into the gap than towards the external surface of said second body. One embodiment of the invention will now be described in more detail in the following description when taken together with the accompanying drawing in which:- Figure 1 is taken from our Published British Application GB-A-20 42 599 and shows schematically a friction spinning apparatus of this type; Figure 2 is an enlarged section on the lines II-II of Figure 1 showing the modified apparatus according to this invention. Referring firstly to Figure 1, the structure and operation of this apparatus is fully disclosed and described in Published British Application GB-A-2 042 599 and those unfamiliar with this apparatus should refer to that specification for a detailed description of the apparatus. The apparatus described therein has been modified according to the present invention by the provision of a feed duct 41′ as shown in Figure 2. The reference numerals used in the following description where possible are the same as used in the above specification. The duct extends to an elongate mouth 45′ positioned closely adjacent and parallel to the line of closest approach of the rollers 1 and 2, that is it extends into the narrowing gap between the rollers to a position closer to the line of closest approach than the radius of curvature of the rollers. As can be seen from Figure 2, the airborne fibres will be discharged from the duct along a direction substantially parallel to the central plane of the nip. In practice the mouth 45′ is spaced less than 10 mms from the yarn formation position which in turn is spaced from the line of closest approach by 2 or 3 mms. The duct 41′ is formed in two parts, that is one plane flat wall 415 which extends vertically and one wall 416 which is complex in shape as including a taper toward the mouth 45′ and all structural parts necessary to co-operate with the flat wall 415 to form the complete feed duct 41′. As described in the above published application, the roller 1 is perforated and includes a suction duct 13 inside including a narrow slot 14 along the length of the rollers to define a narrow elongate area on the roller 1 through which air is drawn. The roller 2 is imperforate. The roller 1 rotates in a direction such that observed from the side of the feed duct 41′ it moves into the gap and the roller 2 moves in the same rotational sense such that it moves out of the gap. The duct 41′ thus, as disclosed in Published Applications GB-A-2 042 599 and in our copending Applications No. 80.32417 GB-A-2 094 843, is arranged to feed the fibres substantially directly into the gap such that some can fall directly onto the yarn. It will be appreciated that it is very difficult if not impossible to determine exactly where the fibres are disposited, but it is clear that this arrangement is different from one wherein the fibres are clearly aimed and directed at the wall of one of the rollers, and are prevented from directly failing onto the yarn. The duct of the present invention is however modified such that the mouth is biassed to the side adjacent the perforated roller 1. More specifically the mouth 45′ opens such that one side lies substantially immediately adjacent the roller 1 while a spacer surface 417 lies between the other side and the roller 2. Of the total mouth width of the order of 75% lies on the side of the central plane (shown at 418) adjacent the roller 1. The inner surface of the wall 416 includes all the taper of the feed duct and is directed such that an extension would intersect the yarn (shown at 419) or the junction of the yarn 419 and the roller 1. The duct may be more biassed than as shown in Fig. 2, but not so far that fibres are prevented from falling directly onto the yarn. The side of the mouth adjacent the roller 2 lies on the same side of the central plane 418 as the roller 2. In this way the duct 41′ tends to direct more of the fibres, than would be the case with the prior arrangements, toward the roller 1. As explained above it is not possible to determine exactly how many fibres are disposited on a particular area but it is clear that the duct has a tendency to direct more fibres toward the roller 1 than toward the roller 2. In addition it should be noted that because the whole of the taper lies in the wall 416, more of the fibres will be travelling on that side of the duct. An explanation for the improved performance cannot be given with certainty because of the difficulty of determining the exact path of fibres but it is believed that the following occurs. A larger proportion of fibres thus is aimed to join the yarn at or adjacent its junction with the roller 1 and a smaller proportion of fibres joins the yarn at the junction between the yarn 419 and the roller 2. Some fibres may first encounter the surface of the roller 1, but they do so at a very shallow angle and for a very short distance and hence their orientation is very little affected by their contact with the roller before they encounter and join the yarn. Fibres which join at the roller 1 are it is believed rolled between the yarn and the roller 1 and hence join the yarn smoothly. Fibres which join at the roller 2 firstly are flung around the upper surface of the yarn by the rotation of the yarn and hence do not join into the yarn as smoothly as those at the roller 1.

Claims: 1. Apparatus for open-end spinning yarn comprising first and second rotatable bodies (1, 2) arranged such that the external surfaces of the bodies define an elongate gap which narrows toward a line of closest approach of the surfaces; means for rotating said first body (1) in a direction so that its external surface, which is perforated moves into the gap and means for moving the second body (2) in a direction so that its external surface which is imperforate moves out of the gap to twist fibres in the gap to form a yarn (419); means for withdrawing the yarn along the gap; and a fibre feed duct (41′) having an elongate mouth (45′) within the gap and arranged to direct a confined flow of fibres substantially directly into the gap along a direction substantially parallel to the direction of movement of the surface of said first body (1) at said line of closest approach such that some fibres can directly join the yarn, characterized in that the fibre feed duct extends to within 10 mm of the yarn formation position and is biased to one side of the central plane (418) of the nip so as to tend to direct more of the fibres toward the external perforated surface of said first body (1) as it moves into the gap than towards the external surface of said second body (2). 2. Apparatus according to claim 1, characterized in that, when viewed in a plane of section perpendicular to the axes of rotation of the rotatable bodies (1, 2), one side wall (415) of the feed duct (41′) is flat and the feed duct has a portion near said elongate mouth which tapers toward the elongate mouth (45′), and in that all the taper of said portion is formed by a part of the opposite side wall (416) being inclined with respect to the flat side wall (415). 3. Apparatus according to claim 2, characterized in that the flat side wall (415) ends adjacent the surface of said first body (1) which moves into the gap. 4. Apparatus according to claim 3, characterized in that the flat wall (415) is substantially at right angles to the plane containing the axes of rotation of the bodies (1, 2). 5. Apparatus according to any preceding claim, characterized in that part of the elongate mouth lies on either side of a plane passing through the yarn (419) and perpendicular to the plane containing the axes of rotation of the bodies. 6. Apparatus according to any preceding claim, characterized in that one side of the elongate mouth lies substantially immediately adjacent the surface of the first body (1) which moves into the gap.

Inventors: CLOUGH, DOUGLAS OWEN, PARKER, ALAN
Applicants: HOLLINGSWORTH (U.K.) LIMITED
Application year: 1982
Main classification: D01H4
IPC codes: D01H4