EP0189919A1

EP0189919A1 - Device for the automatic control of the weft yarn feed in air looms

Info

Publication number: EP0189919A1
Application number: EP86101177A
Authority: EP
Inventors: Luigi Pezzoli
Original assignee: VILMINORE OFFICINE MECCANICHE SpA; OMV Officine Meccaniche Vilminore SpA
Current assignee: VILMINORE OFFICINE MECCANICHE SpA
Priority date: 1985-01-30
Filing date: 1986-01-29
Publication date: 1986-08-06
Also published as: JPS61207642A; ES8700704A1; IT8519294A0; ES551417A0; BR8600330A; IT1215235B

Abstract

A device for the automatic control of the weft yarn feed in air looms comprises at least one sensor (13), which measures the time taken for each yarn turn leaving the feeder (A) to unwind, and an analyzing and monitoring circuit (14), to which are fed the motion analysis signals from the sensor (13) and which continuously monitors the operating times of the solenoid valves (7, 8, 9)-supplying air to the loom nozzles (1, 2, 3) from compressed air receivers (4, 5, 6)-and the air pressure level in said receivers (4, 5, 6).

Description

This invention relates to a device for the automatic control of the weft yarn feed in air looms.
It is known that the proper working of air Looms - in which the weft yarns are inserted into the shed and conveyed therethrough by means of air bLasts, bLowing from nozzles suitably arranged upstream, along and downstream of the shed - greatly depends on the constancy of the physical parameters of the yarn. In fact, any fluctuations in said parameters tend, above all, to easily produce a variation in the "flight" time of the weft yarn. Assuming that the setting is initially optimized for a short "flight", any variations in said physical parameters of the yarn determine a Lengthening of the cycle time, with consequent possibilities of machine stoppage. If the time is set so that, also in these conditions, it may be possible to avoid stoppage (in practice, one should increase the feed pressure of the main nozzle and/or the auxiliary nozzles), the result will be greater consumption - should the yarn conditions subsequently allow shorter flight times - as well as the possibility of defects appearing in the fabric.
On the other hand, constancy of the physical parameters of a yarn is a purely theoretical characteristic, as the said fluctuations practically occur in all yarns, to an obviously greater or lesser extent according to the type and quality of the yarn. It seems therefore extremely important that the working of air Looms should not depend on these fluctuations, and this can be achieved by operating each time according to the characteristics of the yarn being woven, so that the drawbacks deriving from the Lack of constancy of the yarn physical parameters may be eliminated or at Least greatly reduced.
This is the object of the present invention, which concerns a device for the automatic control of the weft yarn feed in air Looms, of the type in which the yarn - fed at one end of the Loom by a known type feeder which draws it from a reel - is inserted into the loom by a drawing-in nozzle upstream of the shed, is conveyed along the shed by a group of feeding nozzles within the shed, and is put under tension by a tensioning nozzle downstream of the shed, said nozzles being supplied from compressed air receivers through suitably controlled solenoid valves. Such a device is characterized by comprising at least one sensor, which measures the time taken for each yarn turn leaving the feeder to unwind - before its rotary-translational motion is turned into a purely transLational motion - and an analyzing and monitoring circuit, to which are fed the motion analysis signals from the sensor and which continuously monitors the operating times of said solenoid valves and the pressure LeveL in said air receivers. If, instead of a single sensor, a number of them are used, distributed in cascade at the periphery of the feeder drum, the time measured by each sensor is not the unwinding time of one turn, but that of the corresponding turn portion.
This device can be realized in various embodiments. For instance, it can comprise a single air receiver for each nozzle or group of nozzles, said analyzer circuit monitoring, on one hand, said solenoid valves and, on the other hand, servo controls associated to said air receivers in order to vary the pressure therein.
The invention is described hereinafter in greater detail, with reference to the accompanying drawings, which represent schematic diagrams corresponding to three different possible embodiments of the device according to the invention.
The drawings show this device applied to an air Loom T, of which the reed and sley P, the nozzle 1 drawing in the yarn f, the group of feeding nozzles 2 and the tensioning nozzle 3, are shown diagrammatically. These nozzles are supplied from compressed air receivers 4, 5 and 6 respectively, by way of solenoid valves 7, 8 and 9, the pressure in the receivers being adjustable by means of servo controls 10, 11 and 12. The yarn f is fed to the nozzle 1 by a conventional weft feeder A which draws it from a reel R.
The device according to the invention, represented by. the diagram of figure 1, simply comprises an optical or piezoetectris censor 13, apt to measure tne time taken for each yarn turn Leaving the feeder A to unwind (before the rotary-translational motion of the yarn, as it emerges from the feeder A, is turned into a purely translational motion, as said yarn is drawn into the Loom T), and an analyzing and monitoring circuit 14, to which the sensor 13 transmits its motion analysis signals. Output signals from the circuit 14 can be sent both to the solenoid valves 7, 8 and 9, and to the servo controls 10, 11 and 12. In this manner, it is possible to continuously vary - throughout Loom operation-both the blowing times of the nozzles 1, 2 and 3, and the air pressure levels in the receivers 4, 5 and 6, according to the times taken for the turns of yarn f to unwind, as measured by the sensor 13; this will allow to obtain the yarn feed conditions which are most suited to the characteristic parameters of the yarn itself. In fact, such parameters directly influence the yarn unwinding speed, as it Leaves the feeder A, said speed corresponding to the times measured by the sensor 13.
It is thereby possible to fulfil the conditions allowing to prevent the yarn feed drawbacks deriving from fluctuations in the physical parameters of the yarn, with considerable advantages both for the progress of weaving operations (which take place more regularly and with Less energy and yarn consumption) and for the quality of the product obtained.
The automatic control device according to the invention can also be realized in other embodiments, differing from that illustrated in figure 1. First of all, instead of a single sensor 13, more sensors (not shown) can be used, evenly or unevenly distributed in cascade at the periphery of the drum of the feeder A. In this case, each sensor monitors only one portion of each turn unwinding from the feeder and thus measures the unwinding time of said turn portion. In addition, as can be seen in the embodiment of figure 2, the nozzles 1, 2 and 3 can be supplied from pairs of compressed air receivers 4A, 48, 5A, 5B and 6A, 68, having different pressure levels, each with its own solenoid valve and servo control. In the embodiment of figure 3, to the ordinary nozzles 1 and 2, supplied from the air receivers 4 and 5, there are furthermore associated supplementary nozzles 21 and 22, supplied from additional air receivers 24 and 25, these also comprising their own solenoid valve and servo control, and a supplementary air receiver 26 is added for the nozzle 3.
If the loom is fed with several yarns of different colours, which require the nozzles to have different blowing times or to be supplied with air at different pressure LeveLs, the automatic control device according to the present invention is equally applicable by simply supplying the analyzing and monitoring circuit 14 - suitably adapted - with the data relative to the colour sequence involved. The circuit will accordingly adapt the air pressures and nozzle blowing times to each type of yarn, by correspondingly setting them - for each colour- to those values which had been set in the previous cycle for the same colour (and type of yarn), such values being then adjusted - as already seen in the case of feeding a single yarn - according to the motion analysis signals transmitted by the sensor 13.
Luminous signals or panels can be associated to the described device, to allow immediate action by the operators if the analysis signals should reveal that the physical degradation of the yarn being weaved is Leading to intolerable consumption by the Loom.
It is understood that the invention could also be carried out differently than in the heretofore described and illustrated embodiments. For instance, the sensor 13 of the device according to the invention - which, in the accompanying drawings, is shown separate from the feeder A - could obviously form part thereof, by being incorporated in said component or associated thereto. This arrangement could also be adopted in the already considered case of using several sensors.

Claims

1) Device for the automatic control of the weft yarn feed in air Looms, of the type in which the yarn - fed at one end of the loom by a known type feeder which draws it from a reel - is inserted into the loom by a drawing-in nozzle upstream of the shed, is conveyed along the shed by a group of feeding nozzles within the shed, and is put under tension by a tensioning nozzle downstream of the shed, said nozzles being supplied from compressed air receivers through suitably controlled solenoid valves, characterized by comprising at Least one sensor (13), which measures the time taken for each yarn turn Leaving the feeder (A) to unwind, before its rotary-translational motion is turned into a purely translational motion, and an analyzing and monitoring circuit (14), to which are fed the motion analysis signals from the sensor (13) and which continuously monitors the operating times of said solenoid valves (7, 8, 9) and the pressure level in said air receivers (4, 5, 6).

2) Automatic control device as in claim 1), comprising a plurality of sensors (13), distributed at the periphery of the feeder drum, each sensor (13) measuring the unwinding time of a corresponding turn portion.

3) Automatic control device as in claim 1), wherein a single air receiver (4, 5, 6) is provided for each nozzle or group of nozzles (1, 2, 3), and wherein said analyzing and monitoring circuit (14) monitors, on one hand, said solenoid valves (7, 8, 9) and, on the other hand, servo controls (10, 11, 12) associated to said air receivers (4, 5, 6), in order to vary the pressure therein.

4) Automatic control device as in claim 1), wherein a pair of air receivers (4, 5, 6), having different pressure LeveLs, are provided for each nozzle or group of nozzles (1, 2, 3), a solenoid valve (7, 8, 9) and a servo control (10, 11, 12) being associated to each air receiver (4, 5,

6), and wherein said analyzing and monitoring circuit (14) monitors, on one hand, said solenoid valves (7, 8, 9) and, on the other hand, said servo controls (10, 11, 12).

5) Automatic control device as in claim 1) wherein, for each nozzle or group of nozzles (1 and 2), there are provided supplementary nozzles or groups of nozzles (21 and 22), supplied from air receivers (24 and 25) being separate from those supplying the main nozzles or groups of nozzles (1 and 2) and having their own solenoid valves and servo controls, and wherein said analyzing and monitoring circuit (14) monitors said solenoid valves and servo controls.

6) Automatic control device as in claim 1), wherein said analyzing and monitoring circuit (14) is furthermore provided to store and process data relative to a sequence of yarns of different colours.

7) Automatic control device as in claim 6), further comprising Luminous signals or panels, indicating the variations in the working parameters of the nozzles (1, 2, 3), as they are produced by the device itself.