EP0009840B1

EP0009840B1 - Weft selection system for looms

Info

Publication number: EP0009840B1
Application number: EP19790200536
Authority: EP
Inventors: Roger R. Lampaert
Original assignee: Weefautomaten Picanol NV
Current assignee: Weefautomaten Picanol NV
Priority date: 1978-10-03
Filing date: 1979-09-25
Publication date: 1984-01-18
Also published as: EP0009840A1; NL174376C; NL174376B; DE2966557D1; NL7809969A; YU223179A; DE9840T1; DE7926892U1; JPS5551849A; ES484648A1

Description

The present invention relates to a weft selection system for looms. The looms therein contemplated are shuttleless multi-colour looms equipped with Jacquard or dobby mechanisms.
It is known that the said mechanisms are actuating a series of pulling hooks and levers, whereby as well the weaving pattern as the various colours may be determined in the fabric. Numerous systems are known for selecting weft threads having different colours and for presenting them to the grippers for example, from US-A-2 814 315; however, a large number of said systems have important drawbacks resulting from the difficult synchronization between the Jacquard or dobby mechanism, the weft insertion motion and the loom, especially at the presently used high weaving speeds.
The object of the present invention is to prevent such drawbacks by providing a new weft selection system which has not the above- mentioned shortcomings.
This object is met according to the invention by a weft selection system comprising the combination of:

- a weft selector comprising a series of levers pivotably mounted on a common shaft, each said lever consisting of two separate lever arms frictionally interconnected on said shaft by means of a friction device, one of said arms being connected to the Jacquard or dobby device, the amplitude of pivoting of the other arm being limited by two stops so that the maximum angular displacement is constant, independently of that of the first arm, each said other arm actuating a respective switch to generate signals corresponding to a selected weft;
- a timing device including a contactless switch S which is energised by rotation of the main shaft of the loom to generate timing signals in phase therewith;
- a synchronisation device receiving said signals corresponding to a selected weft and said timing signals, whereby the signals corresponding to a selected weft are stored until the timing signals are received and then transmitted to
- a weft presented which presents the corresponding weft to the picking means.

The scope of this invention will be more clearly apparent from the following description of a non limitative embodiment given by way of example, reference being made to the enclosed drawings in which:

Figure 1 is a block diagram of the whole device according to an embodiment of the invention;
Figure 2 is a cross-section of the device through which the colour is selected;
Figure 3 is a top view of the double lever according to the arrow F3 in Figure 2;
Figure 4 is a diagrammatic view of a damping disc and the corresponding contactless switch;
Figure 5 is a cross-section of the device presenting the thread; and
Figure 6 is an operating diagram showing the relation between the opening of the shed and the rotation of the main (or driving) shaft of the loom.

The block diagram of Figure 1 gives a general view of the device according to an embodiment of the invention. As known, for each weft, the nature of the weaving pattern and the sequence of the various colours in the fabric are ordered by a Jacquard or a dobby mechanism M. These data are sent to a device consisting of a series of pulling hooks or levers, each lever relating either to the weaving pattern proper or to the colour of the weft thread being presented. However, in the present case, the levers relating to the selection of the colour of the weft thread only are considered. The device in which said levers are disposed in called a colour selector A which additionally comprises also the same number of contactless switches cooperating with the said levers. The signals emitted by said switches are synchronized in a device C with periodical signals produced by a damping disc D mounted on the driving shaft of the loom or of the dobby or Jacquard mechanism, and a contactless switch S, whereby the synchronization device C transmits signals to a device B which then presents the thread to the gripper and which is called for brevity the "weft presenter".
Figure 2 shows a cross-section of a colour selector A in rest position, that is to say in a position in which the concerned colour is not selected. This colour selector A comprises substantially a casing 1 in which are mounted a series of levers 2 and the same number of contactless switches 3. Each lever 2 is actuated by the previously mentioned Jacquard or dobby mechanism M according to the colour selected by the said mechanism for the next following weft. Each lever 2 comprises substantially two individual arms 4 and 5 which are so mounted on a common axis or spindle 6 that a small friction plate 9 made of metal or synthetic material is mounted between their ends 7 and 8 receiving the common axis 6, the said ends 7 and 8 clamping the said small friction plate 9 with a defined force under the influence of a spring 10 mounted on the axis 6. The arm 5 of the lever 2 has a transverse plate-shaped end 11, whereas the end 12 of the arm 4 is provided to cooperate with the Jacquard or dobby mechanism M. The casing 1 has a groove- shaped opening 13 in which the arm 4 of the lever 2 may be freely shifted upwardly and downwardly according to the control of the mechanism M. In the casing 1 is provided a stop 14 preventing the small plate 11 of the arm 5 from being spaced too far from the contactless switch 3 when the arm 4 is moved upwardly. Thus, during the upwards movement of the arm 4, the arm 5 is firstly subjected to a corresponding downwards movement through an angle a until the small plate 11 is retained by the stop 14. When the arm 4 is then still moved further upwardly under the influence of the mechanism M, the ends 7 and 8 of the arms 4 and 5 will be displaced relative to each other on the small friction plate 9. However, as soon as the arm 4 is again shifted downwardly, the arm 5 will be immediately subjected to an upwards movement resulting from the constant friction between the ends 7 and 8 of the arms 4 and 5, namely the friction caused by the small friction plate 9 and the pressure of the spring 10. Thus, already after a minimum downwards movement of the arm 4, the contactless switch 3 will be energized by the small plate 11, which provides a substantial saving of time since it is not necessary to wait until the arm 4 is situated in its lowest position for energizing the switch 3. The maximum distance on which the small plate 11 may be moved, corresponds to the angle a and is determined by the localization of the stop 14, on one hand, and of a stationary stop 15 on the other hand. The contactless switch 3 must be so adjusted that, in the highest position of the small plate 11, a free space is always kept between the said plate 11 and the lowermost portion of the contactless switch 3. The distance which the small plate 11 must be shifted in order to re-energize the switch 3, corresponds to the angle f3 and is characteristic for the used contactless switch.
When the arm 4 is in its highest position as shown with dotted lines in Figure 2, or, in the same manner, when the small plate 11 is in its lowest position, the contactless switch 3 is undamped, thereby producing the signal indicating that the concerned colour has been selected.
According to the invention, the signal for a colour selection may be produced in two ways.
The first way relies on the application of a simple system whereby for each individual colour, there is provided only one double lever and, accordingly, also only one contactless switch. Owing to the fact that this method requires only one lever per colour, some difficulties may be experienced, more particularly when manufacturing multicoloured fabrics which have also an intricate structure pattern since the total number of available levers is anyhow limited.
Nevertheless, this system is advantageous in that, in case of rupture of a lever, no colour is presented and, consequently, after the weft control, the loom is immediately stopped since no weft is presented.
The second way of producing a signal for colour selection comprises using a binary system, whereby n switches are sufficient for selecting 2" different colours. This method relies on the undamping of the contactless switches according to the binary system, in other words the selection of a colour is, in the present case, depending on the fact that a small number of various switches are energized or not. An example of a binary colour selection is given in the following table, wherein 1 = damped and 0 = undamped.
It is apparent that this system may be readily extended for more than 8 colours. For instance, it is already sufficient to introduce a fourth switch for selecting 16 different colours. This method has a great advantage in that a very small number (n) of levers is only required in order to allow the application of a large number (2") colours.
Whatever the used method will be, the colour selector will continuously produce signals corresponding with the colour selected at any moment by the mechanism M. As a consequence of the presently used high weaving speeds, it is necessary to bring these signals for the colour selection in a perfect synchronization with the rotating speed of the loom, in other words, care must be taken so that the pulses produced in the colour selector are introduced perfectly at the exact moment in the weft presenter B. It is the reason why each of the said pulses is firstly stored in a synchronization device C until the said synchronization device receives a pulse coming from the contactless switch S which is periodically damped and de-energized by a damping disc D mounted on a shaft 16 of the loom or the dobby or Jacquard mechanism. The damping disc D passes periodically before the contactless switch S, thereby producing every time a pulse. The localization of the disc D relative to the zero position of the rotating axis of the loom is very critical with respect to the obtaining of a perfect synchronization for presenting the thread to the gripper.
Figure 6 shows a diagram representing the shed opening, in ordinate, as a function of the rotation, in abscissa, of the axis of the loom. This diagram shows the second half portion of a period P_o, a full period P and the first half portion of the following period P₂. The points 18-19 show respectively the beginning and the end point of the full period P l'
At the point 20 of the period P_l, the shed begins to close again and the arm 4 of the lever 2 is in its lowest position when the colour corresponding to said lever 2 has not been selected for the weft corresponding to the preceding period P_o. However, if said colour is now selected for the following period P₂, from the moment corresponding to the point 20, the arm 4 of the lever 2 will be shifted upwardly and the arm 5 will follow this movement in the opposite direction. As soon as the arm 5 is rotated downwardly through an angle [3, the contactless switch 3 is de-energized, thereby producing the signal for the colour selection. This occurs when the axis of the loom is rotated in the period P_o through an angle corresponding with the point 21 in the diagram of Figure 6. When the arm 4 moves further upwardly, the arm 5 will be further shifted downwardly until this movement is blocked by the stop 14. The maximum distance which the arm 5 may be moved downwardly, is determined by the angle α.
The arm 4 may then continue moving upwardly, but the arm 5 is kept in rest position against the stop 14. This is possible owing to the already described double construction of the lever 2.
It is thus apparent that the signal for the colour selection of a weft corresponding to a period P₂ is already produced during the second half portion of the preceding period P_l. In order to provide the synchronization with the movement of the weft presenter B, a pulse must be also produced by means of the already mentioned damping disc D and the contactless switch S which are situated outside the colour selector A, whereby the frequency with which the switch S is energized and de-energized, is directly influenced by the angular speed of the axis of the loom. The damping disc D is preferably displaced by about 270° relative to the zero point of the rotating axis of the loom. The so produced pulse is periodically repeated and it coincides at the soonest with the pulse of the colour selector (indicated at the point 21), and essentially a long time before the moment at which the gripper penetrates the shed of the following period P_Z. The moment at which this pulse is generally produced is indicated by way of example in the diagram by the point 22. Simultaneously, the signals coming from the colour selector are then also transmitted to the weft presenter B (Figure 5).
The weft presenter B comprises substantially a casing 23 in which an electromagnet 24, a hinged armature 25, a cam 26, an intermediate lever 27 and a lever 28 are mounted for each individual colour. When a colour is selected by the mechanism M and via the colour selector A, the pulse produced therein is transmitted at the suitable time, through the synchronisation device C, to the weft presenter B, thereby energizing the electromagnet 24 and pulling downwardly the hinged armature 25.
Through a small wheel 29, a cam 26 imparts a swinging movement to the intermediate lever 27. When no signal is produced for the colour selection, in other words when the hinged armature 25 is in its highest position, the intermediate lever 27 will be able to move freely round the axis 30 since it is not retained by the hinged armature 26 and the thread of the concerned colour will not be presented to the gripper.
However, if the colour is properly selected, the hinged armature 25 is then attracted by the electromagnet 24 and its end 31 will prevent the swinging movement of the intermediate lever 27 round the axis 30. As a consequence of the constant movement of cam 26, in the present case, the intermediate lever 27 will be periodically tilted against the end 31 of the hinged armature 25 so that the axis 30 is laterally reciprocated through the small wheel 29 and the guide 32, thereby also driving an intermediate bar 34 connecting the end 35 of the intermediate lever 27 with the lever 28 which is rotatably mounted relative to an axis 36. As a consequence of this movement, the arm 37 fixedly secured on the lever 28 will present periodically the thread of the desired colour to the gripper. It is apparent that a similar device must be provided for each different colour.

Claims

1. A weft selection system in a loom equipped with a Jacquard or a dobby mechanism and wherein one of a plurality of weft threads is selected by the Jacquard or dobby mechanism and is presented by a weft presenter to weft picking means, characterized by the combination of:

- a weft selector comprising a series of levers pivotably mounted on a common shaft (6), each said lever consisting of two separate lever arms (4, 5) frictionally interconnected on said shaft by means of a friction device, one of said arms (4) being connected to the Jacquard or dobby device, the amplitude of pivoting of the other arm (5) being limited by two stops (14, 15) so that the maximum angular displacement is constant, independently of that of the first arm, each said other arm (5) actuating a respective switch (3) to generate signals corresponding to a selected weft;

- a timing device (S, D) including a contactless switch S which is energised by rotation of the main shaft of the loom to generate timing signals in phase therewith;

- a synchronisation device (C) receiving said signals corresponding to a selected weft and said timing signals, whereby the signals corresponding to a selected weft are stored until the timing signals are received and then transmitted to

- a weft presenter (B) which presents the corresponding weft to the picking means.

2. Weft selection system according to claim 1, characterized in that said friction device comprises a small friction plate (9), e.g. made of metal or synthetic material, said plate being clamped between the said lever arms (4, 5) under the influence of a spring (10) adapted at the level of the said axis.

3. Weft selection system according to claim 1, characterized in that the colour selection is carried out according to a binary system, whereby n levers (4, 5) and the same number of contactless switches (3) allow to select 2n colours.

4. Weft selection system according to claim 1, characterized in that the said weft presenter (B) comprises substantially a casing (23) in which an electromagnet (24), a hinged armature (25), a cam (26), and intermediate lever (27) and a lever (28) are positioned for each colour so that, when a signal for colour selection is introduced into the said colour giver, the corresponding electromagnet (24) is energized, thereby pulling down the hinged armature (25), as a result of which and under the influence of the constant rotating movement of the cam (26), a swinging movement is imparted to the intermediate lever (29) round one end of the said hinged armature (25), whereby this movement is transmitted, through an intermediate bar (31), to a lever (28) provided with an arm (37) presenting the thread to a gripper.