Yarn supply

Abstract: Apparatus for dispensing a predetermined length of yarn (1) in which the yarn (1) is drawn from a yarn supply (2) by a transfer means (3). The transfer means (3) includes one, and preferably two, transfer members (4,5) around which the yarn (1) is wound. Rotation of the transfer member or members (4, 5) draws yarn (1) from the yarn supply (2). The surface speed of the rotating transfer member or members (4, 5) is greater than the speed at which yarn (1) is supplied from the transfer means (3), so the yarn (1) is supplied with substantially no tension. A measuring means (7) measures a predetermined length of the yarn (1) supplied from the transfer means (3).

Description: This invention relates to an apparatus for supplying a desired length of yarn. Yarn is used in a wide variety of production processes, for example knitting, embroidery, lace-making, and carpet making. For many of these processes, for example in a gripper Axminster carpet making process, it is necessary to provide the yarn in a yarn carrier. In our earlier European patent EP-B-0,058,478, we disclose the advantage of supplying predetermined lengths of yarn to a yarn carrier, the length corresponding to that which will be required for the particular process. It is therefore necessary to accurately measure lengths of yarn. In our earlier patent, we disclose a system in which yarn is supplied from a number of packages, and is measured into a separate tube. The yarn is fed into the tube by air jets. As the yarn is fed into the tube, the yarn passes through a pair of measuring rollers, and from the number of rotations of one roller, the length of yarn measured into the tube is determined. The packages of yarn are typically provided in a creel, and yarn is fed from the packages, around a series of guide rollers to the measuring rollers. Depending on the position of the packages on the creel, the yarn is fed around a different number of guide rollers. The tension in the yarn depends upon the number of guide rollers around which the yarn is fed, the length of the yarn to the measuring rollers and, especially where the packages are spools, with the variation in weight of the spools, the tension being lower for yarn drawn from a partially empty spool compared to what for yarn drawn from a full spool. The yarn tends to stretch as it is drawn to the measuring roller. The amount of stretch depends on the dampness of the yarn, and the tension of the yarn. As the amount of stretch varies for each yarn, it is not possible to compensate for this when measuring a length of yarn, and accordingly it is impossible to accurately measure a desired length of yarn. DE-A-817875 discloses a feeding apparatus for yarn or the like wherein the yarn is detensioned before being fed to a knitting machine to allow the knitting machine to produce a knitted product with improved uniformity. According to the present invention, an apparatus for dispensing a predetermined length of yarn comprises a transfer means for drawing yarn from a supply and supplying yarn to a measuring means, the transfer means including a rotatable transfer member around which, in use, yarn is wound so that yarn is drawn from the supply upon rotation of the transfer member, in which the surface of the transfer member is arranged to move at a speed greater than the speed at which yarn is supplied to the measuring means, and wherein said measuring means measures said predetermined length of said yarn while said yarn is under substantially no tension. As the speed of the surface of the rotating member is greater than the speed at which yarn is supplied to the measuring means, the rate at which yarn is drawn into the transfer member will exceed the rate at which it is supplied to the measuring means. Accordingly, the yarn is supplied to the measuring means at a very low tension. This results in constant stretching of the yarn, thereby improving the accuracy of the measurement of length. As the transfer member is a rotating member around which the yarn is wound, any excess yarn supplied to the transfer means causes the yarn to slip on the rotating transfer member and no further yarn is drawn into the transfer means. This prevents excessive yarn from becoming tangled in the transfer means. It is preferred that the speed of the surface of the transfer member is approximately 10% higher than the speed at which yarn is supplied to the measuring means. The measuring means may be in the form of opposed rollers, one of which is rotatably driven to draw yarn from the yarn supply and through the transfer means. Advantageously, the transfer member comprises two capstans, the yarn being wound around both of these. This is advantageous because the size of the rotating transfer member can be reduced, or elongated, without reducing the amount of yarn in the transfer means. It is preferred that two yarn brakes are provided, one before the transfer member and one after. These brakes stop the supply of yarn to the measuring means. Preferably the rotation of the transfer member is stopped after the application of the yarn brakes to reduce wear on the transfer member and on the yarn wound around the transfer member. The apparatus preferably includes a tensioner between the transfer means and the measuring means. This applies a predetermined tension to the yarn as this is supplied to the measuring means. This ensures that the tension of all yarn supplied to the measuring means is constant and accordingly that all yarns are stretched to the same extent. This can be compensated for by the measuring means. The apparatus of the present invention may advantageously be included in an air cell filling apparatus such as that disclosed in our earlier patent EP-B-0,058,478. Where several yarns are supplied to the measuring means, it is advantageous for the transfer means to include a plurality of transfer members, each transfer member arranged to have a single yarn wrapped around it. A particular example of the present invention will be described in accordance with the accompanying diagram. Yarn 1 is supplied from one of a number of yarn packages 2 to the transfer means 3. Some of the yarn packages 2 will be full, and some only partially full. The force required to pull yarn 1 from these packages 2 differs depending on the size and density of the packages, and the distance over which the yarn must be pulled. The yarn 1 is fed into the transfer medium 3, and around two capstan rollers 4, 5. The yarn 1 is fed from the transfer means 3, via a tensioning device such as a pair of opposed nip rollers 6 over a measuring roller 7 to an air cell filling machine. The capstan rollers 4, 5 are arranged to rotate so that the surface of the rollers 4, 5 move at a speed approximately 10% quicker than the speed at which yarn 1 is drawn into the filling machine. The rotation of the capstan rollers 4, 5 assists in drawing yarn from the yarn package 2 into the transfer means 3. When the yarn is tight on the capstans 4, 5, the rotation of the capstans 4, 5 draws yarn 1 from the package 2 into the transfer means 3. This yarn 1 is supplied to the measuring roller 7. As the rotation of the capstans 4, 5 is at a greater speed than that at which the yarn 1 is supplied to the measuring roller 7, the yarn 1 has substantially no tension as it is supplied. As yarn 1 is drawn into the transfer means 3, and yarn 1 is supplied from the transfer means 3 at a lower rate, excess yarn 1 will be contained in the transfer means 3 causing this to become loose on the rotating capstans 4, 5 and accordingly the yarn 1 will slip on the surface of the capstans 4, 5 and yarn 1 will not be drawn into the transfer means 3. This prevents an excessive build up of yarn 1 in the transfer means 3 which could become tangled. As yarn 1 is supplied from the transfer means 3, the yarn 1 again tightens on the capstans 4, 5 and accordingly more yarn 1 is drawn into the transfer means 3 from the package 2. In this way, the tension in the yarn 1 supplied from the transfer means 3 to the measuring roller 7 is always constant. It is desirable to have a known low tension on the yarn 1 being fed to the measuring roller 7, and accordingly a pair of opposed rollers 6 are provided to pinch the yarn 1 with a predetermined force, thereby generating the required tension. The yarn 1 is fed over a measuring roller 7 which is rotated by the flow of the yarn 1 over its surface. As the tension in the yarn 1 is known, the amount of stretch of the yarn 1 is also known, and therefore the rotation of the roller 7 corresponds to the amount of yarn 1 dispensed. Alternatively, a pair of opposed measuring rollers may be included. In this case, one of the measuring rollers is a driven roller which draws yarn 1 from a package 2, through the transfer means 3 and the tensioning device 6. The length of yarn is calculated by the rotation of the other measuring roller.

Claims: Apparatus for dispensing a predetermined length of yarn comprising: a transfer means (3) for drawing yarn (1) from a supply (2) and supplying yarn (1) to a measuring means (7), the transfer means (3) including a rotatable transfer member (4, 5) around which, in use, yarn (1) is wound so that yarn (1) is drawn from the supply (2) upon rotation of the transfer member (4, 5), in which the surface of the transfer member (4, 5) is arranged to move at a speed greater than the speed at which yarn (1) is supplied to the measuring means, and wherein said measuring means measures said predetermined length of said yarn (1) while said yarn (1) is under substantially no tension. Apparatus according to claim 1, in which the speed of the surface of the transfer member (4, 5) is approximately ten percent higher than the speed at which yarn (1) is supplied to the measuring means (7). Apparatus according to claim 1 or 2, in which the measuring means (7) comprises a pair of opposed rollers, one of which is rotatably driven to draw yarn (1) from the yarn supply (2) and through the transfer means (3). Apparatus according to any one of the preceding claims, in which the transfer means (3) comprises two capstans (4, 5), in use the yarn (1) being wound around both capstans (4, 5). Apparatus according to any one of the preceding claims, further comprising two yarn brakes, one before the transfer means (3) and one after, arranged to stop the supply of yarn (1) to the measuring means (7). Apparatus according to claim 5, further comprising a means to stop the rotation of the transfer means (3) after the application of the yarn brakes. Apparatus according to any one of the preceding claims, further including a tensioner (6) between the transfer means (3) and the measuring means (7), the tensioner (6) being arranged to apply a predetermined tension to the yarn (1) as this is supplied to the measuring means (7). Apparatus according to any one of the preceding claims, in which the transfer means (3) includes a plurality of transfer members (4, 5), each transfer member (4, 5) arranged to have a single yarn (1) wrapped around it. An air cell filling apparatus including the apparatus according to any one of the preceding claims.

Inventors: PILLING JOHN REGINALD, WESTON PAUL ANTHONY RICHARD, PILLING, JOHN REGINALD, WESTON, PAUL ANTHONY RICHARD
Applicants: BRINTONS LTD, BRINTONS LIMITED
Application year: 1996
Main classification: D03D47
IPC codes: B65H61, B65H51, D03D47, B65H59, D03D39