FR2619580A1 - Device for varying the length of reference reserve yarn, intended to be used in association with a device for measuring and storing the weft yarn - Google Patents

Abstract

Device 1 for varying the length of reference reserve yarn, intended to be used in association with a device 2 for measuring and storing weft yarn for a loom. This device 1 varies a length of reference reserve yarn, that is to say a length of a weft yarn 4 necessary for one insertion cycle, to be stored on the storage drum of the device 2 for measuring and storing weft yarn, depending on the variation in the unwinding tension of a weft yarn 4 unwound from a package 3. The unwinding tension of the weft yarn 4 is measured directly or indirectly by a tension sensor during the unwinding of the weft yarn 4 from the package 3. A control member 7 produces a control signal corresponding to the unwinding tension on the basis of a measurement signal produced by the tension sensor 6, and a unit 8 for varying the length of reference reserve yarn increases or reduces automatically the length of reference reserve yarn for the device 2 for measuring and storing weft yarn on the basis of the control signal produced by the control member 7.

Description

 The present invention relates to a jet loom, more particularly to a device intended to vary a length of reference reserve thread, that is to say a length of thread necessary for a weft insertion cycle. , according to the variation of the unwinding tension of a weft thread unwound from a winding.

 The unwinding tension of a weft thread unwound from a winding varies according to the outside diameter of the winding. As the tension of the weft thread measured varies according to the variation of the unwinding tension, the length of the weft thread inserted in a weft insertion cycle varies due to the variation of the tension of the weft thread during the measurement of the length, that is to say of the variation of the unwinding voltage, even if the weft yarn measurement and storage device operates stably.

 An invention presented for example in Japanese patent 60-28550 provides a device which marks the actual position of arrival of the free end of a weft thread inserted during an insertion cycle and adjusts the length of reserve thread on the basis of the tracking result for controlling the measurement operation so that weft thread of fixed length is inserted at each insertion cycle. When this known device is used, the length of the weft thread inserted is always constant despite the variation of the launching conditions as well as the variation of the unwinding tension. However, as this known device has a series of locating heads aligned in the insertion direction to mark the position of arrival of the free end of the inserted weft thread, the lost length of the inserted weft thread, i.e. the length of the removed selvedge, inevitably increases , and if the locating heads are moved so as to reduce the length lost, it is possible that the ends of the lathe threads do not block the free end of the inserted weft thread, that the stubborn locating locates by mistake the turn ends for the inserted weft thread, or that excess length weft threads are thrown to temporarily increase the weft thread loss because a series of control actions are triggered after the length of the thread of inserted frame increased excessively.

 Consequently, an object of the present invention is to provide a device for varying the length of reference reserve thread capable of suitably varying the length of reference reserve thread according to the variation of the tension of the weft thread during the unwinding. of it from a winding based on the degree of variation of this voltage.

 For this purpose, according to the present invention, the unwinding tension of the weft thread is captured directly or indirectly by a tension sensor during the unwinding of the weft thread from a winding, a control member produces a control signal corresponding to the variation of the unwinding voltage on the basis of the output signal from the voltage sensor, then appropriate means automatically vary the length of reference reserve wire according to the control output signal produced by the control member.

 In such a control mode, the variation of the unwinding voltage is transformed into a control signal, so that the control is carried out with satisfactory response characteristics and a simple and effective control operation is possible.

 According to the present invention, the unwinding tension, which increases progressively as the outside diameter of the wire winding decreases, is grasped directly or indirectly and said means rapidly vary the length of reference reserve wire on the basis of the result of the entry. Therefore, pieces of weft yarn of fixed length are stably inserted despite the variation of the weft yarn when measuring and storing it on a measuring and storing device, and thus a ideal length of the inserted weft thread is fixed to reduce the weft thread waste.

The objects, characteristics and advantages above as well as others of the present invention will appear better on reading the following description illustrated by the accompanying drawings, in which
fig. 1 is a functional diagram showing the basic constitution of a device for varying the length of reference reserve wire in a preferred embodiment according to the present invention,
fig. 2 is a graph showing the variation of the unwinding tension with the decrease in the outside diameter of the wire winding,
fig. 3 is a graph showing the variation in the length of the reserve wire with the decrease in the outside diameter of the wire winding,
fig. 4 schematically shows a device for varying the length of the reference reserve wire in a first embodiment according to the present invention,
fig. 5 schematically shows a device for varying the length of reference reserve wire in a second embodiment according to the present invention,
fig. 6 schematically shows a device for varying the length of reference reserve wire in a third embodiment according to the present invention,
fig. 7 is a longitudinal section of a drum used in the third embodiment,
fig. 8 is a front view of the drum of FIG. 7,
fig. 9 schematically shows a device for varying the length of reference reserve wire in a fourth embodiment according to the present invention, and
fig. 10 is a front view of a retaining finger used in the fourth embodiment.

 Fig. 1 shows the basic construction of a device for varying the length of reference reserve wire 1 according to the present invention.

 The reference reserve wire length variation device 1 is intended to be used in combination with a weft wire measurement and storage device 2 of a type with measuring rollers and rotating storage drum, a type with measuring rollers and air bath or a type with measuring and storage drum.

The weft yarn measurement and storage device 2 unwinds a weft yarn 4 from a winding 3, measures the length of the weft yarn 4 and sets aside a length of weft yarn 4 necessary for insertion. During the insertion of the weft thread 4, an insertion nozzle 5 pulls the reserve weft thread 4 from the measurement and storage device 2 and passes it through a crowd.

 The reference reserve wire length variation device 1 of the present invention comprises as essential elements a voltage sensor 6, a control block 7 and a reference reserve wire length variation block 8. tension 6 is placed between the wire winding 3 and the weft yarn measurement and storage device g to measure the unwinding tension of the weft yarn 4 unwound from the winding 3 and send to the control unit 7 a signal representing a measured wire feed voltage. Then, the control block 7 produces a control signal corresponding to the variation of the unwinding voltage on the basis of the voltage signal sent to it by the tension sensor 6 to actuate the variation block of the reserve wire length. reference 8. Consequently, this block 8 varies a length of reference reserve wire for the weft wire measurement and storage device 2 according to the control signal to cope with the variation of the unwinding voltage due to the variation of the outside diameter of the wire winding 3.

 As mentioned above, the weft yarn measurement and storage device 2 unwinds the weft yarn 4 from the winding 3, measures the length of the weft yarn 4 unwound and stores a measured length thereof for the cycle of 'insertion which follows. At an instant determined for insertion, an insertion nozzle 5 draws a necessary length of weft thread 4 from the measurement and storage device 2 and passes it through the crowd.

 As the insertion operation advances, the unwinding tension of the weft thread 4 increases progressively with the progressive decrease of the outside diameter of the winding 3 due to the variation of the physical properties of the weft thread 4, on which the crimping of wire 4, and the variation of the ball of wire 4 unwound. The tension sensor 6 picks up the unwinding tension of the weft thread 4 and sends to the control block 7 a signal representing this tension. The control block 7 processes the tension signal on the basis of a fixed correlation function to produce an appropriate control signal corresponding to the variation of the unwinding voltage for actuating the reference reserve wire length variation block 8. This block 8 then increases the reference reserve wire length for the measuring and measuring device. weft yarn storage 2 according to the decrease in the outside diameter of the yarn winding 3 as shown in fig. 3. Consequently, the length of the inserted weft thread is always constant despite the variation of the unwinding tension of the weft thread 4 during the measurement operation of the thread measurement and storage device 2.

 Thus, the wire feed voltage during the measurement and storage operation is increased as the wire feed voltage increases. When the weft thread measured in the aforementioned state is inserted a force to be applied in the direction of elongation of the weft thread, that is to say a tensile force, does not act on the inserted weft thread. Consequently, the inserted weft yarn 4 shrinks in the crowd of the warp yarn and is liable to shorten relative to a fixed length.

In particular, this tendency appears clearly when a hard twist thread or a textured thread is inserted. However, according to the present invention, the unwinding tension of the weft thread 4 is measured before the thread measuring and storing device 2 and the length of reference reserve thread for this device 2 is modified on the basis of the tension. of measured wire feed. Consequently, the length of the weft thread 4 passed through the shed and released from the winding tension coincides with the fixed length.

 As mentioned above, the weft yarn measurement and storage device 2 is of a type with measuring rollers and rotating storage drum, of a type with measuring rollers and air bath or of a drum type for measuring and storing, and the block for varying the length of reference reserve thread 8 is produced in different forms described below according to the type of device for measuring and storing weft thread 2.

First realization (fig. 4)
A device for varying the length of reference reserve wire, in a first embodiment according to the present invention, is designed to be used in combination with a device for measuring and storing weft yarn 2 of a type with measuring rollers. and rotary drum for storage and has, as a block for varying the length of reference reserve wire 8, a rotating mechanism with variable speed, for example a speed variator of the trapezoidal belt type 80.

 Two windings of wire 3 are provided, the rear end of the wire 4 of one and the front end of the wire 4 of the other being joined. The weft thread 4 unwound from the first winding 3 passes, guided by thread guides 9, by a tension sensor 6 then goes, guided by a thread guide 10, with two measuring rollers 20 and is then wound up on a rotating drum 21 The free end of the weft thread 4 laid on the rotating drum 21 goes, passing through a thread guide 11 and a clamp 12, to an insertion nozzle 5. On the other hand, a shaft on which is mounted the rotating drum 21 is driven by the main loom of the loom through the speed variator 80.

A shaft on which one of the measuring rollers 20 is mounted is driven by the shaft of the rotating drum 21 by means of a transmission mechanism having an appropriate gear ratio and comprising two friction wheels 22 in engagement, l one fixed to the shaft of the rotating drum 21 and the other fixed to the shaft of the measuring roller 20. The speed ratio of the variator 80 can be modified progressively by actuation of a speed regulator 81.

 The tension sensor 6 senses the unwinding tension of the weft thread 4 unwound from the winding 3 and sends a signal representing this tension to the control member 70 of a control block 7. When one of the windings 3 supplying the weft thread 4 is exhausted, this is supplied by the other winding 3. The replacement of the winding 3 exhausted by the full winding 3, that is to say say the winding change, is detected by a sensor 14.

When the winding change is detected, this sensor 14 sends a signal to the control unit 70 of the control unit 7. A control signal produced by the control unit 70 is transmitted by an actuation unit 71 to the pulse motor 82 of the reference reserve wire length variation block 8.

 The wire feed voltage gradually increases with the decrease in the outside diameter of the wire winding 3. The controller 70 produces a control signal corresponding to a wire feed voltage increment to actuate the pulse motor 82 in corresponding angular steps to the control signal so as to increase the speed ratio of the variator 80, so that the respective rotational speeds of the rotating storage drum 21 and the measuring rollers 20 are increased. Thus, the length of the reference reserve thread is gradually increased as the outside diameter of the thread winding 3 decreases, that is to say that the unwinding tension of the weft thread 4 increases. of weft 4 is temporarily stored on the rotating drum 21, then the weft thread 4 is unwound from the drum 21 and launched into the crowd by the action of the clamp 12 and of the launching nozzle 5.

 When replacing the exhausted winding 3 by the full winding 3, the winding change sensor 14 sends a signal to the control member 70. This is reset to an initial control mode, so that the variable speed drive 80 is quickly set to an initial gear ratio to quickly process the winding change.

Second realization (fig. 5)
A device for varying the length of reference reserve wire, in a second embodiment according to the present invention, is designed to be used in combination with a device for measuring and storing weft yarn 2 of a type with measuring roller. and air bath.

This reference reserve wire length variation device directly controls the respective amounts of rotational movement of a measuring roller 23 and a measuring drum 24. In this embodiment, the unwinding tension of the weft wire 4 is determined indirectly by measuring the weight of the wire winding 3.

 The weft thread 4 is pinched between the measuring roller 23 and the measuring drum 24. The length of the weft thread unwound from the winding 3 is determined by measuring the respective amounts of rotational movement of the measuring roller 23 and the drum. measure 24. The weft yarn 4 measured is sent to a distribution case 26 by a stream of air produced by a nozzle 25 and is stored there. On the other hand, the wire winding 3 is supported by a support 60, for example in L supported by a pin 63.

The weight of the wire winding 3 supported by the support 60 is sensed by a weight sensor 61 associated with the support 60. This sensor 61 sends a signal representing the weight of the corresponding wire winding 3 to a control unit 70 at the weft wire feed tension 4.

The controller 70 then adjusts a wire storage control circuit 72 at a fixed division ratio. This circuit 72 divides a fixed number of pulses. produced by a rotation detector 73 for detecting the rotation of the main shaft 13 of the loom to send a set speed of rotation to a motor 83 serving as a variable rotary mechanism. An encoder 84 detects the speed of rotation of the motor 83 and sends a reduction signal to the wire storage control circuit 72.

That is to say, this circuit 72 is a digital servomechanism for correspondence regulation which regulates the speed of rotation of the motor 83 according to that of the main shaft 13 on the basis of the given division ratio.

Thus, the respective speeds of rotation of the measuring roller 23 and the measuring drum 24 are gradually increased with the increase in the unwinding tension of the weft thread 4, that is to say the reduction in the weight of the wire winding 3, to progressively increase the length of the weft wire 4 stored in the distribution box 26 according to the decrease in the weight of the wire winding 3.

Third realization (fig. 6, 7 and 8)
A device for varying the length of reference reserve wire, in a third embodiment according to the present invention, is designed to be used in combination with a device for measuring and storing weft yarn 2 of a measuring drum type. and storage and employs as a reference reserve wire length variation block 8 a drum diameter variation mechanism.

 As shown in fig. 6, the weft yarn measurement and storage device 2 of a measurement and storage drum type comprises a fixed storage drum 28, a rotating yarn guide 27 which rotates to empty the weft yarn 4 on this drum 28, and a retaining finger 29 intended to retain the thread 4 laid on the drum 28. At the time of insertion, the retaining finger 29 is separated from the surface of the fixed storage drum 28 by an operating block 30 to allow an insertion nozzle 5 to draw the weft thread 4 from the drum 28 and pass it through the crowd. A motor 39 rotates the wire guide 27. The operating speed of this motor 39 is controlled according to the speed of rotation of the main shaft 13 of the loom by a digital servomechanism comprising a control circuit 74 and encoders 40 , 73.

 As shown in fig. 7 and 8, the storage drum 28 has a fixed wall part 31 which is located opposite the retaining finger 29. The rest of the circumference of the storage drum 28 is formed by several movable wall parts 34 each supported by parallel bars 32 and each drawn radially inwards by a spring 33. A roller 35 mounted to rotate on the leg of the movable wall part 34 is in contact with the circumference of an axially movable conical cam 36 whose axis coincides with the axis of the storage drum 28.

This conical cam 36 is screwed onto a threaded rod 37, and a guide rod 38 ltemp8che to rotate. A pulse motor 85 rotates the threaded rod 37.

 While the weft wire feed tension 4 gradually increases during the weft wire measurement and storage operation, a control member 70 controls an actuator 71 to actuate the pulse motor 85 so that the tapered cam 36 is moved towards this motor 85 (to the left in FIG. 7), so that the movable wall parts 34 are moved radially outwards to increase the outside diameter of the storage drum 28. Consequently, the length of the reference reserve thread, that is to say the length of the weft thread necessary for an insertion cycle, is gradually increased according to the increase in the unwinding tension of the weft thread 4.

Alternatively, a cam-bar mechanism such as that presented in Japanese Patent 60-28550 can be used for varying the outside diameter of the storage drum. r '
Fourth realization (fig. 9 and 10)
A reference reserve wire length variation device, in a fourth embodiment according to the present invention, is designed to be used in combination with a weft measurement and storage device 2 similar to that used in the third embodiment , the variation in the length of the reference reserve thread being this time produced by selective actuation, by means of maneuvering thereof, of retaining fingers 29 intended to retain the weft thread 4 on a storage drum .

 As shown in fig. 9 and 10, a series of retaining fingers 29a, 29b, ..., 29n are placed at regular circumferential intervals P around the circumference of a storage drum 28 of fixed outer diameter. These retaining fingers 29 are selectively actuated by associated operating blocks 30 which are themselves actuated by a retaining finger actuation circuit 86. Naturally, this circuit 86 operates in synchronism with the rotation of the shaft. main 13 of the trade on the basis of a control signal sent to it by a control member 70 and a pulsed signal sent to it by a rotation detector 73. The unwinding voltage of the weft thread 4 is determined indirectly by measurement diameters of wire windings 3 by diameter sensors 62 each associated with a wire winding 3.

 Suppose, when measuring and storing on the storage drum 28 a length of weft thread 4 necessary for an insertion cycle, that is to say a length of reference reserve thread, this length corresponds to four turns of weft yarn 4 which are formed when the retaining finger 29a is approached the circumference of the storage drum 28. Then, when the retaining finger 29a is moved back and the retaining finger 29c advanced, the length of reference reserve wire is brought to (four turns + 2 P). Thus, the length of reference reserve wire can be gradually increased by advancing and retreating the retaining fingers 29 sequentially one at a time. The circuit 86 actuates the operating blocks 30 sequentially one at a time to put the retaining fingers 29 in action sequentially so as to increase the length of the reference reserve thread progressively according to the increase in the unwinding tension of the weft thread 4.

Variants r
Although the first to fourth embodiments have been described in association with different elements to explain the different modes of practical application of the present invention, the preceding embodiments are susceptible of various variants. For example, the variable speed drive 80 of the first embodiment and the motor 83 are interchangeable. The voltage sensor 6 can be as it was originally designed for entering the voltage or can be replaced for the weight sensor 61 or by the diameter sensor 62.

 Although the invention has been described with some thoroughness in its preferred form, it goes without saying that many modifications and many changes are possible in the invention without departing from the scope thereof.

Claims (6)

 1 - Device for varying the length of reference reserve wire (1) intended to be used in association with a device for measuring and storing weft yarn (2) which measures the length of a weft yarn (4) and stores a length thereof necessary for a weft insertion cycle until the stored weft thread (4) is inserted, comprising a) a tension sensor (6) for measuring the tension  weft thread (4) during its unwinding from a winding  ment (3), b) a control block (7) which receives the output signal  of the voltage sensor (6) and produces a com signal  command corresponding to the unwinding tension, and c) a block for varying the length of the reserve wire.  reference (8) which increases or reduces a length of  reference reserve wire for the  measurement and storage of corresponding weft yarn (2)  to a length of wire required for an in cycle  setting on the basis of the control signal produced by  the control unit (7).  2 - device for varying the length of reference reserve wire (1) according to claim 1, with which the device for measuring and storing weft wire (2) is of a type with measuring rollers and the block of variation of reference reserve wire length (8) comprises a variable speed mechanism (80, 83) operatively placed between a source of rotational movement and the measuring rollers (20, 23).  3 - device for varying the length of reference reserve wire (1) according to claim 1, with which the device for measuring and storing weft yarn (2) is of a drum type for measuring and storing and the reference reserve wire length variation block (8) comprises a diameter variation mechanism (32, 34, 36, 37, 85) capable of varying the outside diameter of the measuring wire storage and storage drum weft (28) of the weft yarn measurement and storage device (2).  4 - device for varying the length of the reference reserve wire (1) according to claim 1, with which the weft wire measurement and storage device (2) is of a drum and measurement and storage drum type. the reference reserve wire length variation block (8) comprises a mechanism for selective actuation of retaining fingers (30, 86) capable of selectively actuating one of the retaining fingers (29) placed around it of the measuring and storage drum (28) of the weft yarn measuring and storage device (2).  5 - Device for varying the length of reference reserve wire (1) according to one of claims 1 to 4, in which the tension sensor (6) is a weight sensor (61) capable of measuring the weight of the wire winding (3).  6 - Device for varying the length of the reference reserve wire (1) according to one of claims 1 to 4, in which the tension sensor (6) is a diameter sensor (62) capable of measuring the outside diameter of the wire winding (3).