Carpet weaving

Details Carpet weaving Carpet weaving

2002-11-14

2004-03-09

Calvert, John J. (Department: 3765)

Textiles: weaving

Pile tufting

Portable supply

C139S00700A, C139S00700A, C139S00700A, C139S00100C

Reexamination Certificate

active

06701970

ABSTRACT:

BACKGROUND TO THE INVENTION
In making carpet, particularly patterned Axminster carpet, a yarn tuft forming unit is used to provide yarn of a particular colour to each weaving point of the carpet. In conventional Axminster weaving there are two principal ways which the yarn tuft formation is carried out. The first way is on a Jacquard Axminster loom, and the second is on a spool Axminster loom.
On a gripper Jacquard Axminster loom each weaving point includes a yarn carrier which is normally fed by eight yarns usually of different colour and the Jacquard mechanism moves the carrier to bring a selected yarn to the yarn selection position. A gripper moves towards the carrier, grips the yarn at the yarn selection position then relative movement apart of the gripper and the carrier pulls a predetermined length of yarn from the carrier. The yarn is then cut to form a tuft and moved by the gripper to the weaving point. The tuft carried by the gripper is of the appropriate colour for the tuft to be supplied to the next row of carpet to be woven. For a conventional 12 foot (4 m) loom there are over a 1000 weaving points across the loom and thus the creel supplying yarn to the loom has to have the potential of carrying over 8000 yarn packages. Typically, when the creel includes measured quantities of yarn in each yarn package, an allowance of an additional eighteen metres of yarn is provided in each yarn package. Accordingly, the greater the number of yarn packages the greater the wastage. In spite of such a large creel size a designer of such carpets is relatively limited since the number of colours available for each column of tufts extending in the warp direction of the finished carpet and corresponding to a single weaving point is limited to only eight throughout each pattern repeat. Jacquards are also known in which the yarn carrier can hold sixteen different yarns. These require an even larger creel.
Spool Axminster looms provide a designer with greater flexibility. In spool Axminster looms a separate spool is provided for each row of the pattern repeat and each spool has a separate yarn winding for each weaving point along each row. Therefore, at least theoretically, the designer has an infinite number of colour choices for each column and row of each pattern repeat. However, in practice, as the number of colour choices used for each column and row of the design increases, the number of yarn packages needed for the spool winding operation also increases. Further, the spool winder must be set up differently for the winding of each spool which is time consuming. When a large number of different colours are used in both the column and row or warp and weft direction of each pattern repeat the number of different coloured yarn packages supplying the spool winder can be even larger than those on a creel of a typical Jacquard Axminster loom. The pattern repeat on spool looms is limited by the number of spools available in the spool chain. Further, there is considerably greater yarn wastage from a spool Axminster loom than a gripper Axminster loom because, on completion of a run, waste is generated from each weaving point of each row of the pattern repeat.
DISCUSSION OF PRIOR ART
In both the Jacquard and spool Axminster looms a row of tufts for a complete row of the carpet is created simultaneously and transferred to the weaving point at which they are woven into a backing to produce the carpet. An entirely different approach to yarn selection for carpet production has recently been proposed in WO 95/31594. In this, it is proposed that tufts of yarn to form a row of the carpet are produced by first loading yarn tufts into a tuft carrier and then transferring the yarn tufts from the tuft carrier to the weaving points. To achieve this a large number of different tuft forming units, typically one per weaving point, are provided along the length of a path with typically each tuft forming unit being supplied with yarn of only a single colour. As the tuft carrier is moved along the path it receives tufts of appropriate colour in each of its tuft holding sites. The tuft carrier is subsequently moved so that all the tufts for each row can be gripped by grippers and transferred to the weaving point simultaneously. Thus, the tufts are not usually all formed simultaneously and hence the tuft formation is, at least to some extent, decoupled from the weaving operation. Therefore, tuft formation can take place at the same time as the weaving operation and thus tuft formation can take place substantially continuously throughout the operation of the loom. This is to be contrasted with conventional spool or gripper type looms where tuft formation takes place over only about half of each weaving cycle.
In examples given in WO 95/31594 it is suggested that partly as a result of forming the tufts throughout the entire weaving cycle it is possible to, for example, increase the speed of the tuft forming operation by four times. It is also explained that if this were possible and it was intended to operate the loom at the same speed as a conventional loom then it would be possible to reduce the size of its creel to a quarter since, in effect, each tuft forming unit would supply tufts for four weaving points. However, nowhere in this document does it exemplify an arrangement in which there are less yarn packages than the number of weaving points.
Whilst the above document specifically exemplifies only the supply of yarn of a single colour to each tuft forming unit it does disclose the theoretical possibility of providing yarn of a number of different colours to each tuft forming unit and somehow, in an unspecified way, selecting yarn of an appropriate colour for each weaving point. If this teaching is followed the creel size would not be reduced significantly. The document also discusses the theoretical possibility of holding the yarn carrier stationary whilst moving the tuft forming unit. However, neither of these theoretical possibilities are exemplified nor is it explained how they could be achieved nor what advantages would accrue.
SUMMARY OF THE INVENTION
According to this invention a carpet weaving loom includes at least one tuft forming unit for forming sequentially yarn tufts of a number of different colours, means to receive and hold at yarn tuft holding sites yarn tufts supplied sequentially by the tuft forming unit, and transfer means to transfer all of the tufts held by the yarn tuft holding sites simultaneously to their corresponding weaving points, the or each tuft forming unit supplying yarn tufts to at least twenty yarn tuft holding sites between successive operations of the transfer means.
The number of tuft forming units provided on the loom varies with the width of the loom and its required operating speed. For example, on a loom used to make carpet samples there will usually only be a single tuft forming unit and this tuft forming unit may supply tufts to, for example, three hundred, or more, tuft holding sites. On a typical twelve foot (4 m) loom there may be twelve tuft forming units each supplying tufts to less than one hundred and twenty holding sites and typically around eighty tuft holding sites. However, to be able to operate such a loom at the highest possible speed the number of tuft forming units may be increased to twenty four or even thirty with each supplying just over forty or about thirty five tuft holding sites. In the case of there being more than one tuft forming unit these are preferably subsequently equidistantly spaced across the loom.
Taking the typical case given above of a twelve toot (4 m) loom including twelve tuft forming units and assuming an equal choice of different yarns, eight, as used in a typical conventional gripper Axminster loom, the creel of such a loom only requires ninety six different yarn packages. This is nearly a hundred-fold decrease in the number of yarn packages from that required in the conventional loom. Taking the case of thirty tuft forming units this still leads to at least a thirty-fold decrease in the number of yarn packages. Reducing the

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