EP0081502B1

EP0081502B1 - Woof preparation device for pneumatic looms

Info

Publication number: EP0081502B1
Application number: EP19820901581
Authority: EP
Inventors: Johan T. Peeters; Filip N. Deconinck; Hugo A. Markey
Original assignee: Weefautomaten Picanol NV
Current assignee: Picanol NV
Priority date: 1981-06-17
Filing date: 1982-05-26
Publication date: 1985-04-17
Also published as: JPS619423B2; EP0081502A1; WO1982004446A1; JPS58500952A; DE3263098D1

Abstract

Woof preparation device for pneumatic looms, of the type consisting of a stationary stock-drum (4), on which a stock of woof thread (10) is being wound before it becomes pneumatically transported through the shed, whilst at this delivery end there is provided a blocking component (14) which is shifted from a position of rest to an active position in order to prevent the unwinding of the thread (10) during a part of the weaving cycle, characterized in that at the aforesaid delivery end there is provided a winding counter (16), whereby the shift from rest to the active position of the aforesaid blocking component (14) is being controlled.

Description

The present invention relates to a woof preparation device for pneumatic looms.
Woof preparation devices are already known, which mainly consist of a stationary stoεkdrum on which the woof thread is wound and of mechanical means which, for every shot, separate the necessary number of windings from the following ones and release same for delivery to the main blower of the loom (FR-A-1478294). It is also known to provide a movable thrust piece or blocking component at the delivery end of the aforesaid drum, whereby the delivery of woof thread is prevented during a part of the weaving cycle.
Under normal circumstances such arrangements work in a satisfactory way. They have, however, the drawback of a possible inaccuracy concerning the number of windings effectively delivered each time. This inaccuracy may result from one or more of the following facts:

- the aforesaid mechanical separating means work in a rather static manner;
- these separating means cannot be adjusted according to the thickness of the thread, when one shifts from a thinner to a thicker woof thread or inversely;
- the aforesaid blocking component is, directly or indirectly exclusively controlled as depending from the angular position of the main shaft of the loom. On the other hand, the introduction speed of the woof on a pneumatic loom is subject to variations from shot to shot and from one kind of thread to another.

The object of the invention is now to eliminate the problems mentioned hereinabove.
For, this there is proposed a woof preparation device of the type described hereinabove, wherein, according to the invention, at this delivery end of the stock-drum there is provided a winding counter, whereby the shifting of the aforesaid blocking component, from the retracted position to the blocking position is controlled.
The invention is more clearly explained hereinafter with the help of an example of execution illustrated by means of the attached schematic drawings. In these drawings,

Figure 1 shows a schematic side view of a device according to claim 1,
Figure 2 shows a block diagram of the circuit of the sender-receiver located adjacent to the winding end,
Figure 3 shows a block diagram of the circuit of the other sender-receiver.

In a support 1 mounted on the frame of a pneumatic loom a shaft 2 is rotatably mounted. This shaft is made so as to be partially hollow and carries a thread winder 3. On the shaft 2 a stock-drum 4 is rotatably mounted. The shaft 2 can be driven by means of an electric motor 5, the feeding of which is controlled by two optic detectors 6 and 7.
A magnet 8 carried by the support 1 cooperates with a little iron block 9 provided in the drum 4 to prevent any rotation of the drum.
The woof thread 10, coming from a spool 11 passes through shaft 2 and winder 3 in order to be wound by the latter around the drum 4 and reaches further, through a clamp 12, the main blower 13 of the loom.
At the delivery end of the drum 4, there is provided a blocking component 14, which can be shifted from the active to the passive position and inversely by means of an electro-magnet 15.
The motor 5 is fed with current as long as detector 6 does not detect thread and this feeding stops as soon as detector 7 detects thread.
Means not shown, known themselves in principle, may be provided to ensure the displacement of the windings from one end of the drum to the other.
The electro-magnet 15 is being controlled either through a determined angular position of the main shaft or by means of the programmation of the loom, whereby the component 14 of the drum 4 becomes retracted (passive position). The returning of this component of the active position is controlled, according to the invention, by means of a counter 16 which is provided at the delivery end of the drum 4. In this case this is an optic detector which cooperates with a little mirror 17 carried by the drum 4. The detection signals are counted in a counter 18 properly speaking. As soon as a desired number of signals is reached, the feeding of electro-magnet 15 becomes interrupted until it is put again on the programmation at the intervention of the main shaft.
The drum 4 is preferably of a known type with a continuously adjustable diameter, so that the number of windings that are required per shot may remain constant, whatever the selected weaving breadth. This, however, does not exclude the possibility for the counter 18 to be adjustable.
The controlling device according to the invention is described hereinafter.
An oscillator 19 (figure 2) controls an infrared diode of sender-receiver 6. The rays that are reflected on a reflecting plane 20 of the stock-drum 4 are received by a photo-transitor, which is amplified in 21 and further rectified in 22 to be sent to the switch 23. When the plane 20 is covered by thread, the reflected signal is weak and the rectified signal is non-existent. Switch 23 then remains open.
If the stock of thread disappears, the rectified signal becomes high, so that the switch 23 becomes closed. At this moment, a regulating circuit 24 controls a thyristo r 25 so that the motor r 5 sta rts rotating. A tachometer with impulse giver 26 delivers a signal which is compared by the regulation circuit 24 with a value set by means of 27. Via the thyristor 25, the circuit 24 regulates the speed of the motor 5 so that it becomes equal to the set value.
One may set 27, independently of the quantity of woof to be delivered, in such a way that the motor 5 must start and stop a minimum number of times.
The fixing of the length of woof that is unwound each time takes place through counting a determined number of windings of the drum 4 with a known circumference during the pulling off of the thread and, when this number is reached, controlling the magnet 15 of the blocking component 14. The change of the aforesaid number of windings may be seen as a rough adjustment, whilst the fine adjustment is preferably carried out through modifying the circumference of the drum.
The sender-receiver 16 (figure 3) is a part of a regulating circuit 28 which tries to adjust always in the same working area the signals received by 16, this in order to eliminate the influence of dust deposition on the thread, undesired light and aging.
From the control box 29 of the loom comes a signal which is produced by a time burst given by a clock.
This signal is used as a "set" for a flip-flop 30 which via a power stage 31 controls the little magnet 15 either to clamp or to release the thread.
In 32 there is formed a control area as well of the signals coming from the time control as of the ones of the receiver 16, this in order to avoid incorrect countings due for instance to dust, between two thread passages.
The detected signal is transmitted to the counter 33 only when both the signal of the control 32 and of the detection 16 are high.
This counter 33 is adjustable and will, for instance, send a reset signal to the flip-flop only at the third thread.
At that moment, the magnet 15 becomes energized and the thread is braked. The adjustment of the detector 16 and magnet 15 is such that the magnet, after a count of three, has just the time of a winding left to attract.
An additional blower 34 is also controlled via a valve 35 by the time burst 29 and is used for increasing the speed of the thread when unwinding; (this blower is in fact an auxiliary blower of the main blower).
A second valve 36 ensures that in the stopped position there still remains a slight pressure on the main blower 13, so that the thread remains taut. In the case of the net falling out, the valve will be ruled out, whereby an unnecessary unwinding of the woof will be prevented.
It is clear that the woof preparation device and circuits described hereinabove can be executed in various shapes.

Claims

1. Woof preparation device for pneumatic looms, of the type consisting of a stationary stock-drum (4), on which a stock of woof thread (10) is wound before it is pneumatically transported through the shed, whilst at this delivery end there is provided a blocking component (14) which is shifted from a position of rest to an active position in order to prevent the unwinding of the thread (10) during a part of the weaving cycle, characterized in that at the aforesaid delivery end there is provided a winding counter (16), whereby the shift from rest to the active position of the aforesaid blocking component (14) is controlled.

2. Woof preparation device according to claim 1, characterized in that the aforesaid blocking component (14) is controlled by an electro-magnet (15), the feeding of which is regulated, on the one hand, by means of a signal coming from the main shaft (2), respectively by means of the programmation of the loom, and, on the other hand, by means of a signal coming from the aforesaid winding counter (16).

3. Woof preparation device according to claim 1, characterized in that the winding counter (16) consists of the combination of an optic detector with a counter (18) properly speaking.

4. Woof preparation device according to one or more of the claims 1 through 3, characterized in that the sender-receiver (6) of the winding end is a part of a circuit whereby a driving motor (5) for a winding device is being controlled, whilst the other sender-receiver (7) is a part of a circuit that controls the aforesaid blocking component (14) in order to unwind each time the desired length of thread.

5. Woof preparation device according to claim 4, characterized in that the aforesaid driving motor (5) is equipped with a tachometer and an impluse giver (26), the output of which is being compared in a regulation circuit (24) with a value that can be set at will, whilst the output of this regulation circuit (24) regulates the feeding of the motor (5) via a thyristor (25) in such a manner that the speed of rotation corresponds to the set value.

6. Woof preparation device according to claim 5, characterized in that the regulation circuit (24) is controlled by means of a switch (23) which receives the amplified and detected signals of the sender-receiver (6) at the winding end.

7. Woof preparation device according to claim 4, characterized in that the blocking component (14) is controlled through a flip-flop (30), which becomes set by means of a signal coming from the control box (29) of the loom, this signal being compared each time with the signal coming from the sender-receiver (16) at the delivery end of the drum (4).

8. Woof preparation device according to claim 7, characterized in that the flip-flop (30) is being reset by means of a counter (33), which counts the controlled signals coming from the sender-receiver (16) at the delivery end.