Abstract:
A mechanism for a gripper Axminster loom is disclosed which includes a plurality of yarn carriers each of which is movable to any one of a plurality of predetermined positions. Each carrier guides a plurality of tuft yarn and is arranged to present one of the yarns to a gripper when the carrier is located at a corresponding one of the predetermined positions. The mechanism includes a plurality of independently controllable rotary drive motors, each of which is connected to drive an associated carrier for selectively moving the associated carrier to a selected one of the predetermined positions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a tuft yarn selection mechanism and in particular, but not exclusively, an axminster loom incorporating such a selection mechanism. 
     2. Related Art 
     When weaving on a typical gripper axminster loom the carpet normally has three weft yarns per tuft loop (three shot carpet) whereas carpet woven on other types of loom usually have two weft yarns per tuft loop (two shot carpet). 
     The weft yarns are inserted in succession and so a 50% increase in carpet production can be achieved on an axminster loom if two weft yarns could be inserted without loss of insertion speed. 
     With a conventional axminster loom the speed of operation of the tuft yarn selection mechanism is too slow to enable correct selection of tuft yarns to be achieved for a two shot operation. 
     A general aim of the present invention is to provide a tuft yarn selection mechanism which operates at a sufficiently high speed to enable a twoshot carpet to be produced on gripper axminster loom without loss of insertion speed. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention there is provided a tuft yarn selection mechanism for a gripper axminster loom, the mechanism including a plurality of yarn carriers each of which is movable to any one of a plurality of predetermined positions, each carrier guiding a plurality of tuft yarns and being arranged to present one of said yarns to a gripper when the carrier is located at a corresponding one of said predetermined positions, and a plurality of independently controllable rotary drive motors, each drive motor being drivingly connected to an associated carrier for selectively moving the associated carrier to a selected one of said predetermined positions. 
     Preferably, each motor is an electric motor and is electrically controlled to move the associated carrier to said selected one of said predetermined positions. 
     Preferably the electric motor is a stepper motor. 
     Preferably each carrier has associated therewith sensing means for determining the position of the carrier and providing a signal indicative of the carrier being located at a selected one of said predetermined positions. 
     The sensing means may be used to determine arrival of the carrier at a selected one of said positions and thereby provide a signal to control stopping of the motor. Alternatively, electronic control means may be provided which transmit to the stepper motor a sufficient number of pulses to move the carrier from one position to the selected position, the sensor being arranged to confirm correct positioning of the carrier. In the event that the carrier is not correctly positioned (eg. it has overshot slightly), the sensor is used to provide a signal which is utilised by the electronic control means to correctively re-adjust the position of the carrier. 
     Preferably the yarn carriers are elongate and arranged to move longitudinally between said predetermined positions. 
     According to another aspect of the present invention there is provided a mechanism for a gripper axminster loom, the mechanism including a plurality of yarn carriers each of which is movable to any one of a plurality of predetermined positions, each carrier guiding a plurality of tuft yarn and being arranged to present one of said yarns to a gripper when the carrier is located at a corresponding one of said predetermined positions, and a plurality of independently controllable drive motors, each drive motor being drivingly connected to an associated carrier for selectively moving the associated carrier to a selected one of said predetermined positions, each drive motor being removably mounted to enable the drive motor to be disconnected from said associated carrier. 
     According to another aspect of the present invention there is provided a mechanism for a gripper axminster loom, the mechanism including a plurality of yarn carriers each of which is movable to any one of a plurality of predetermined positions, each carrier guiding a plurality of tuft yarn and being arranged to present one of said yarns to a gripper when the carrier is located at a corresponding one of said predetermined positions, and a plurality of independently controllable drive motors, each drive motor being drivingly connected to an associated carrier for selectively moving the associated carrier to a selected one of said predetermined positions, monitoring means for each carrier arranged to provide a signal indicative of the position of the associated carrier, and control means responsive to said signal in order to independently control the motor associated with each carrier. 
     Preferably the electric motors are arranged in groups, the motors of each group being mounted upon a common support. 
     According to another aspect of the present invention there is provided a gripper axminster loom adapted to weave a two-shot carpet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: 
     FIG. 1 is a side view of a first embodiment according to the present invention; 
     FIG. 2 is an end view of the first embodiment shown in FIG. 1; 
     FIG. 3 is a side view of a second embodiment according to the present invention; 
     FIG. 4 is an end view of the second embodiment; and 
     FIG. 5 is an enlarged view of a motor and pinion gear shown in FIG.  3   
    
    
     DETAILED DESCRIPTION 
     A tuft yarn selection mechanism  10  according to a first embodiment shown in FIGS. 1 and 2 and includes a plurality of elongate tuft yarn carriers  12 . Each carrier  12  is provided with a plurality of yarn guides  14  to which tuft forming yarns  15  are fed. 
     The yarn guides  14  are spaced from one another along the length of the carrier  12  and the carrier  12  is slidably mounted in guide blocks  13  for longitudinal movement such that any one of the yarn guides  14  can be moved into registry with a gripper  16 . 
     The gripper  16  draws yarn  15  from a guide  14  which has been presented thereto in order to form a tuft in a known manner. 
     As is conventional, there is a gripper  16  for each tuft site in the loom and a yarn carrier  12  for each gripper  16 . 
     Accordingly across the width of the loom, there is provided a large number of yarn carriers  12  which are arranged side by side and are closely spaced. This is illustrated, in a representative manner, in FIG.  2 . 
     Each yarn carrier  12  is moved longitudinally by an individual rotary drive motor  6  to any one of a plurality of predetermined longitudinal positions each of which corresponds to a guide  14  being in registry with the associated gripper  16 . 
     Preferably each drive motor  6  is arranged to drive a pinion gear  30  which meshes with a rack  31  on the associated yarn carrier  12 . In FIG. 1, the motor  6  is preferably drivingly connected to its associated pinion gear  30  by a timing belt  33  and pulley  7 . 
     Preferably a sensor  40  is provided which senses the presence of individual markers  41  which correspond in number to the number of yarn guides  14 . The markers  41  are spaced along the length of the carrier  12  by the same spacing as guides  14  and so provide an indication as to the position of guides  14 . 
     Electronic control means (not shown) are provided which control each motor  6  in order to move its associated carrier  12  in the desired direction and by the desired distance in order to move a selected yarn guide  14  into registry with the gripper  16 . 
     Preferably the sensor  40  acts to provide a signal which is indicative of the carrier  12  arriving at a desired position, the signal being utilised by the control means to stop movement of the carrier  12  by arresting the motor  6 . The motor  6  then acts to temporarily hold the carrier  12  at its selected position. 
     The motor  6  may be a stepper motor. In such a case, the control means may act to supply a predetermined number of pulses to the stepper motor in order to move the carrier  12  from one position to another position. The sensor  40  may then be utilised to confirm that the carrier  12  is correctly positioned, and if not, enable the control means to correct positioning of the carrier. 
     Conveniently the markers  41  are defined by slots formed in the carrier  12  and preferably the sensor  40  comprises an optical sensor which is capable of sensing the presence of the slots. 
     Preferably the motors  6  and associated pinion gears  30  are arranged in groups with all motors  6  and pinion gears  30  of each group being mounted on a common support  50 , preferably in the form of a plate  51  which is removably mounted on the loom frame. 
     This has the advantage of enabling a faulty motor  6  to be quickly removed and replaced by removal of a plate  51  having the faulty motor  6  and replacement by a new plate  51 . With such an arrangement, the replacement of a motor  6  may be carried out without moving the carriers  12  and disturbing yarns  15 . 
     As seen in FIG. 1, the pinion gears  30  are spaced apart in the longitudinal direction of the carriers  12  and the plate  51  is preferably mounted so as to extend at an inclined angle laterally relative to the carriers  12  such that adjacent pinion gears  30  may engage with the racks of adjacent carriers  12 . 
     If the shafts  22  on which the pinion gears  30  are mounted project perpendicularly from the plate  51 , the gears  30  will have an axis of rotation which is not perpendicular to the longitudinal axis of the rack on associate carrier  12 . This misalignment can be accommodated by the provision of suitable gear teeth on the pinion gear and/or rack. 
     Alternatively, the shafts  22  of the pinion gears  30  may be mounted so as to project from the plate  51  at an acute angle so as to ensure that the axis of rotation of each pinion gear is perpendicular to the longitudinal axis of the rack. 
     The motors  6  are preferably arranged in two rows extending parallel to the longitudinal direction of the carriers. 
     With this arrangement, it is possible to accommodate relatively large motors  6  for driving closely spaced carriers  12 . It will be appreciated that, in each group of motors  6 , the motors  6  may be arranged in one row or in more than two rows. 
     A second embodiment  60  is illustrated in FIGS. 3 to  5 , wherein parts similar to those in the first embodiment are referenced by the same reference numerals 
     In embodiment  60 , each motor  6  is arranged to directly drive an associated pinion gear  30  via a drive gear  61 . Accordingly in the second embodiment, all motors  6  carried by the common support plate  51  are arranged in one row. The plate  51  is inclined across adjacent carriers  12  to enable individual pinion gears  30  to mesh with an associated carrier. 
     In embodiment  60 , sensor  40  for sensing the position of the associated carrier has been repositioned to co-operate with the teeth  37  of the associated pinion gear  30 . In this respect the sensor  40  is preferably an optical sensor which is arranged to detect the spaces between the pinion teeth  37  as the pinion gear rotates. 
     Accordingly, in embodiment  60 , markers  41  on each carrier  12  have been dispensed with. 
     Optionally, a further sensor  140  may be provided for co-operating with a marker  141  on each carrier  12 . The marker  141  is positioned along the carrier to indicate a desired reference position, preferably a mid-way position in the travel of the carrier  12 . This enables each carrier to be moved to the reference position and enables calibration of sensors  40  to be achieved. 
     In addition, if desired, the provision of sensor  140  in combination with marker  141  enables each carrier  12  to be moved to its mid-position prior to being moved to the next selected position of the carrier for delivering a desired yarn to the associated tuft gripper. 
     In the above embodiments, motors  6  are electrically powered. It will be appreciated that they may be fluid powered in which case the control means would be arranged to control flow of fluid to the motors in order to control movement of the carriers. 
     It will be appreciated that the carriers  12  are moved by motors which act independently of one another and independently of the main drive shaft of the loom. 
     It will be appreciated that by appropriate control from the control means, each carrier  12  can be individually controlled to move from one position to another selected position at any desired time within the weaving cycle and at any desired speed. It is therefore possible with the present invention to quickly and accurately position the carriers  12  in a gripper axminster loom to enable two-shot carpet to be produced.