EP1564320B1 - Shedding mechanism for a loom - Google Patents

Description

The invention relates to a shed forming device for a weaving machine.

Weaving machines have a so-called shedding device, which serves to guide warp threads according to a weave pattern out of the warp thread level up or down, so that by the spread warp threads a so-called compartment arises. In this a weft is entered (weft insertion). Shedding can for example be done by means of so-called healds, through the eye each running a warp thread. The healds are held on a frame called hedge. The heald must be moved up and down in rapid succession according to the working cycle of the weaving machine. Modern weaving machines generally have several healds, which are arranged closely adjacent one behind the other. The different shafts are assigned to different warp threads. Depending on which shafts are guided up or down, different compartments can be formed to produce the desired bond (cartridge) between warp and weft yarns. So-called dobby machines are usually used to drive the shafts, which derive the shaft movement of the main drive of the loom by appropriate gear means.

It has already been proposed several times to move the shafts individually by suitable servo drives. For example, the disclosed DE 198 21 094 A1 an electromagnetic drive. The shaft is connected according to an embodiment with two electromagnetic drive devices serving as linear drives. Pull and push rods connect the movable member of the electromagnetic drive with the shaft. The electromagnetic linear drives are arranged below the shaft.

It is known from the same document to arrange the electromagnetic linear drive next to the shaft and the horizontal working direction of the drive via a suitable transmission in the vertical implement suitable gear in the vertical working movement of the shaft.

This principle encounters limits when several shafts are to be arranged closely adjacent to one another and to be driven accordingly. Usually, the shafts are in a pitch of 12 mm. The space available for the electromagnetic linear drives space is thus extremely limited, so that hardly any practical solutions can be achieved.

From the JP 2003-89940 A It is known to drive Webschäfte a loom by servomotors. For this purpose, each weaving shank is assigned a servomotor. The servomotors are arranged one above the other in a corresponding drive box arranged laterally next to the weaving machine in two planes. Each servomotor actuates a connecting rod via an eccentric. Angle levers below the heald frames deflect the roughly horizontally oscillating connecting rod movement into vertical oscillation. The two angle levers are interconnected by a pull and push rod.

A similar arrangement is from the EP 1 215 317 A2 known. However, this publication additionally discloses the arrangement of servomotors in more than two levels one above the other, wherein the servomotors offset from each other or vertically aligned with each other can be arranged.

In the drive means according to the last two mentioned documents, difficulties and limitations with respect to the operating speed may result as a result of the transmission elements inherent inert masses and by bearing clearances.

The EP 0 879 909 A1 proposes to move the heald frames by means of linear direct drives or electric linear motors. Because of the narrow pitch of the heald frames, that is, because of the small spacing thereof, this again encounters problems with regard to the accommodation of the linear drives.
The DE 101 11 017 A1 tries to overcome the disadvantages mentioned with special disk-like constructed electric motors whose rotor forms a long lever. The latter is connected via a connecting rod with the hive. The special motors can be arranged in pairs opposite each other and arranged in several levels. As a result, twice or four times the axial shaft thickness is available for the axial length of the motors. Nevertheless, the axial length of the motors is limited in this concept. In addition, at least when the motors are arranged in different planes, different connecting lengths occur, which in turn can lead to difficulties.

On this basis, it is an object of the invention to provide a shedding device, which is improved in terms of the formation of their drive device.

The shed forming device according to the invention has a plurality of heald frames, to which individual drive devices are assigned. The drive devices each form a cluster, which is arranged below the group of heald frames. For each drive means includes at least one servo motor with a lever attached to its output shaft, which is connected via a connecting rod with the heald is. It is envisaged that the levers of the servomotors are oriented in different spatial directions, when the heald frames are in rest position. This measure makes it possible to arrange the servomotors side by side and one above the other in several planes, without the need for complicated intermediate gears in order to convert the rotational movement of the servomotor into a linear movement of the heald. Servomotors of almost any length can be used, even with a large number of heald frames, such as 12 or 16. This, in turn, opens the way to relatively slender servomotors whose outer diameter is less than the length of the lever operated by them. Lean servo motors usually have a very low moment of inertia, which allows the achievement of high shaft accelerations. In addition, as a result of the lack of length limitation, the servomotors can have a suitable length for achieving the required drive torque.

The measure, which has attached to the servomotors and moving from these levers in rest position in different spatial directions, opens the way to a total of compact design. The free pivoting ends of the levers are all located at the center of the cluster defined by the servomotors, ie, the servomotor group concerned. Thus, the heald frames can be connected to the levers with essentially uniform connecting rods. The distance between the heddles and the servomotor group can be relatively low and yet sufficiently large connecting rod lengths are achieved. The levers of the upper servomotors of a servomotor group point down to the lower connecting rod ends while the levers of the lower servomotors of a servomotor group up to the connecting rods point. The ends of the driven levers are all approximately in the same central area surrounded by the servomotor group. Here also ends the lower connecting rods. The servomotors of the servomotor group thus use both the space area above the lower connecting rod end and the space area below it for arranging the servomotors. This leads to a compact space-saving design and a short power transmission path. The existing between the servomotors and the heald frames can be made easily and low backlash, which accommodates both the increase in the operating speed and the increase in life.

The axes of the servomotors are preferably arranged on a circle or an ellipse. This results in a clear arrangement and reasonably symmetrical drive ratios for different servomotors on a servomotor group.

The servomotors are preferably connected to a control device which guides the heald frames according to a control signal. In a simplest case, the control signal is a switching signal. It instructs the servomotor in question to transfer the heald shaft assigned to it into its upper or lower end position. In this mode, the non-linear gear ratio, which form the connecting rod and the lever plays a minor role. But it is also possible to guide the shaft in proportion to a control signal. In this case, the control device preferably has a characteristic block, which is the non-linear Transfer characteristic of the lever mechanism compensated. The different servomotors can each be assigned individual characteristic blocks. From the perspective of the control device thus results in a linear drive, in which each shaft follows its control signal proportional.

Further details of advantageous embodiments of the invention are the subject of the drawing, the description or claims.

Figur 1

eine erfindungsgemäße Fachbildeeinrichtung in schematisierter, perspektivischer Darstellung,

Figur 2

die Fachbildeeinrichtung nach Figur 1 in ausschnittsweiser, schematisierter Vorderansicht,

Figur 3

die Fachbildeeinrichtung nach Figur 1 und 2 in einer ausschnittsweisen, schematisierten Draufsicht,

Figur 4

die Fachbildeeinrichtung und ihre Steuereinrichtung in einer schematisierten Funktionsdarstellung,

Figur 5

eine abgewandelte Ausführungsform der erfindungsgemäßen Fachbildeeinrichtung in einer ausschnittsweisen, schematisierten Vorderansicht,

Figur 6

die Fachbildeeinrichtung nach Figur 5 in Draufsicht,

Figur 7

eine weitere abgewandelte Ausführungsform einer Fachbildeeinrichtung in ausschnittsweiser Vorderansicht,

Figur 8

die Fachbildeeinrichtung nach Figur 7 in Draufsicht und

Figur 9

eine abgewandelte Ausführungsform einer Fachbildeeinrichtung in Funktionsdarstellung.

In the drawings, embodiments of the invention are illustrated. Show it:

FIG. 1

a shed forming device according to the invention in a schematic, perspective view,

FIG. 2

the shedding device according to FIG. 1 in a fragmentary, schematized front view,

FIG. 3

the shedding device according to FIG. 1 and 2 in a fragmentary, schematized plan view,

FIG. 4

the shedding device and its control device in a schematic functional representation,

FIG. 5

4 shows a modified embodiment of the shed forming device according to the invention in a fragmentary, schematized front view;

FIG. 6

the shedding device according to FIG. 5 in plan view,

FIG. 7

a further modified embodiment of a shedding device in a sectional front view,

FIG. 8

the shedding device according to FIG. 7 in plan view and

FIG. 9

a modified embodiment of a shedding device in functional representation.

In FIG. 1 is a shedding device 1 illustrated, to which twelve heald 2 belong. Of these are in FIG. 1 six healds 3 to 8 illustrated. The heald frames 2 are each formed by a rectangular frame with upper and lower, usually horizontally arranged shaft rod. The ends of the shaft rods are interconnected by so-called side supports. The heald frames 2 are used for the storage and management of strands 9, the ends of which sit on non-illustrated heddle rails. The strands 9 are flat flexible metal elements, each with at least one thread eyelet 11 for guiding the warp thread. The strands 9 preferably sit with some longitudinal play (vertical play) on the corresponding heddle rails. If a heald 3 to 8 up or down out (ie adjusted in the longitudinal direction of the strand) while the other heald remain in place, creates a subject in which a weft can be entered (weft insertion).

The heald frames 2 are relatively flat with respect to the warp threading direction. Usually they each claim little more than 12 mm, so that a correspondingly close arrangement of the heald frames 3 to 8 is recorded. Nevertheless, they must be able to be moved individually or independently of each other as quickly as possible up or down. The purpose of this is in FIG. 1 schematically illustrated drive means 12, to which two or more servomotor groups 13, 14 belong. The servomotor groups 13, 14 are mirror images of each other in this embodiment. The following description of the servomotor group 14 thus applies correspondingly to the servomotor group 13. The reference numerals introduced in the description of the servomotor group 14 are therefore in FIG FIG. 1 repeated at the servomotor group 13. The description of the servomotor group 14 applies correspondingly to the servomotor group 13, taking into account the mirror-image arrangement.

To the servomotor group 14 includes six servomotors 15 to 20, each carrying a lever 21 to 26. The lever is rotatably connected to an output shaft of the respective servomotor 15 to 20, which defines a rotation axis 27 to 32. The servomotors are how particular off FIG. 2 the example of the servomotor group 13, so arranged that their axes of rotation 27 to 32 are arranged on an imaginary circle 33. The levers 21 to 26 point with their free ends to the center of this circle 33. With respect to the circle 33, the levers 21 to 26 are thus oriented substantially radially. At least they are oriented so that the end of the respective lever 21 to 26 can reach the center of the circle 33 in the context of his working movement.

The servomotors 15 to 20 are as out FIG. 1 and 3 shows axially offset from one another, so that the ends of the levers 21 to 26, relative to the longitudinal direction of the axes 27 to 32 staggered in the longitudinal direction one behind the other. The longitudinal offset of the servomotors 15 to 20 corresponds to the division defined by the heddle shafts 3 to 8. The servo motor 15 is arranged so that its lever 21 is below the heald 3. The servo motor 16 is arranged so that its lever 22 is below the heald 4. Accordingly, the other servomotors 17 to 20 are offset so that the lever 26 of the servomotor 20 is finally below the heald 8.

The free ends of the levers 21 to 26 are each hingedly connected to one end of a connecting rod 34 to 39, whose respective upper end is hingedly connected to the associated weaving shank 3 to 8. The connecting rods 34 to 39 are preferably substantially the same length and arranged parallel to each other. The connection between the servo motor 15 to 20 and the respective associated weaving shank 3 to 8 is thus achieved only by two hinge points, namely in each case a hinge point between the weaving shank and the connecting rod and a second pivot point between the connecting rod and the associated lever. Such a compound is low backlash and also fraught with low inertial masses. The axes 27 to 32 of the servo motors are preferably distributed on the circle 33 as in FIG. 2 illustrated. The axes 28, 31 are in mirror image with respect to a defined by the connecting rod 34 vertical 41. In the least possible angular distance above the servomotors 16, 19, the servomotors 15, 20 (up to the axial offset) are mirror images of each other. The same applies to their axes of rotation 27, 32. The axes of rotation 28, 31 define a horizontal 42. With respect to these horizontal lines, the servomotors 17, 18 and their axes 29, 30 are arranged in mirror image to the servomotors 15, 20 or their axes 27, 32. In this arrangement, close the levers 21, 26 with the associated connecting rods 34, 39 each have an acute angle, for example, about 45 °. The levers 22, 25 close with the associated connecting rods 35, 38 in the rest position in each case a right angle. The levers 23, 24 close with the associated connecting rods 36, 37 in each case an obtuse angle of for example 135 °. The levers 21 to 26 are preferably approximately the same length. They aspire star-shaped from away from the center of circle 33. The axes of rotation 30, 31, 32 define an isosceles triangle. The same applies to the mirrored axes of rotation 27, 28, 29.

As FIG. 3 illustrates, belongs to the complete shaft assembly, a second group of healds 3 'to 8', which in turn is driven by a servo motor group 13 '. the servomotor group 13 'and the heald frames 3' to 8 'are mirrored to the above-described group of heald frames 3 to 8 and the servomotor group 13 with respect to a vertical plane. The vertical plane is in FIG. 3 perpendicular to the plane of the drawing and runs parallel to the heddle shafts 3 to 8. Accordingly, the description of the servomotor group 13 applies accordingly to the servomotor group 13 '. The description of the heddle shafts 3 to 8 applies accordingly to the heddle shafts 3 'to 8'. There is also a mirrored servomotor group to the servomotor group 14, which is not further illustrated. Thus, the healds 3 to 8 and 3 'to 8' are arranged by a total of four servo motor groups comprising a total of 24 servomotors.

FIG. 4 illustrates the control of the servo motors 15, 16, 17 by a control device 43. This is exemplified only for the servomotors 15 to 17. It also has corresponding inputs and outputs for all other servomotors. The servomotors 15 to 17 are representative of these, the servomotor 15 is typical of all other servomotors, the lever with the connecting rod in the rest position forms an acute angle. The servomotor 16 is typical of all servomotors whose levers with the associated connecting rods in rest position approximately includes a right angle. The servomotor 17 is typical for all servomotors whose lever with the associated connecting rod in the rest position encloses an obtuse angle.

All servomotors 15 to 17 each have a control input which is supplied with control power via a corresponding line or a line bundle 45 to 47 from the control device 43. This can consist in control voltage, control currents and / or corresponding current pulses. Each servo motor 15 to 17 has a position detection device, such as a resolver or similar position sensor, which are connected via corresponding signal lines 48, 49, 50 with the control device 43. For each servomotor 15 to 17, this contains a position control loop 51, 52, 53, which ensures that the angle of rotation assumed by the respective lever 21 to 23 corresponds to a signal value pending at a nominal value input input 54, 55, 56.

During the rotation of the servomotor 15, 16, 17 or its lever 21, 22, 23, the angle between the lever 21 to 23 and the connected connecting rod 34 to 36 changes. In addition, the connecting rod 34 to 36 pivots out of its vertical orientation. Consequently, the stroke of the connected heald 3, 4, 5 is not proportional to the rotation angle of the lever 21 to 23. It also does not follow proportionally to the control signal at the setpoint input input 54 to 56. To compensate for these different nonlinearities obtained at least two of the position control loops 51st to 53, but preferably all three, a characteristic block 57, 58, 59 by a characteristic curve is stored, the individual transmission characteristic of the associated Servomotor 15 to 17 is adjusted. It is set so that it completely compensates for the transmission characteristic, ie linearizes or together with this gives a desired function. In this way it can be achieved that all three healds 3, 4, 5, which are connected to the servo motors 15, 16, 17, respond to control signals at the control inputs 61, 62, 63 the same. The different transmission kinematics are compensated.

The shed forming device 1 described so far operates as follows:

In rest position are the healds 3 to 8 (as well as the heald 3 'to 8'), as in FIG. 1 illustrated, in a position from which they can be deflected downwards, for example, both upwards and as needed. However, the rest position can also be set so that the heald frames can only be deflected in one direction, eg only upwards. The levers 21 to 26 are then in the rest position preferably below the center of the circle 33. The warp threads run substantially horizontally through the eyelets 11 and lie in a common plane. If now through the strands 9 of the heald 3 running warp threads are deflected out of the warp thread plane, the servomotors 15 of the servo motor groups 13, 14 are driven accordingly. You will get to the control input 61 ( FIG. 4 ) a signal that specifies the path-time course of the hive 3. This signal may be an analog signal or a digital signal. The characteristic block 57 converts this path signal into an angle signal for the servomotor 15. The control loop 51 then ensures that the servomotor 15 follows this angle signal. Accordingly, the lever 21st swiveled downwards or upwards (clockwise or counterclockwise) as desired. Accordingly, the hive 3 is raised or lowered. Thus, the desired shed is formed and the weft can be entered.

The described process can be carried out in a corresponding manner for all other servomotors 16 to 20 in order to raise or lower the respectively associated weaving shafts 4 to 8 and to form corresponding compartments. The control of the servomotors 15 to 20 is carried out according to a predetermined pattern, so that the desired binding of the fabric is achieved. The work of the servomotors 15 to 20 is also synchronized to the work of the other organs of a loom, which serve for weft insertion, for striking or for carrying out other operations.

The FIGS. 5 and 6 illustrate a modified embodiment of the shed forming device according to the invention 1. It differs from the embodiment described above by the number of movable heald 3 to 8, 8a, 8b, which is sixteen here. Further heddle shafts 8c (8c ') can be provided which are immovably mounted and to which no drive device is assigned. The heald frames 3 to 8b (3 'to 8b') are in turn associated with servo motor groups 13, 14, 13 ', 14' whose basic structure follows the servomotor group 13, 14 Figure 1 to 3 similar. However, each servomotor group 13, 14, 13 ', 14' here comprises in each case eight servomotors 15, 16, 17, 17a, 18a, 18, 19, 20 which are arranged on an imaginary circle. Their levers 21, 22, 23, 23a, 24a, 24, 25, 26 are directed towards the center of the circle. They are over connecting rods with the heald frames 2 connected and each individually assigned individually. The angular distances of the servomotors 15 to 20 are not uniform. Between the servomotors 17a, 18a and 15 and 20 each have a gap is provided which is substantially greater than the distances between the other, closer adjacent servomotors 15 to 17a and 18a to 20. The servomotors 15 to 20 are, as well as in the above embodiment, arranged so that in the rest position none of the levers 21 to 26 forms an angle with the associated connecting rod, which is smaller than 40 °. Preferably, the angle is not less than 45 °. In this way it is achieved that the different transmission characteristics formed by the lever-connecting rod connection do not deviate too much from each other and by the characteristic blocks 57 to 59, according to FIG FIG. 4 , are compensatable.

Another on the embodiment according to Figure 1 to 3 constructive embodiment of the invention is from the FIGS. 7 and 8 seen. It is based on the above description, in particular in connection with the FIGS. 1 to 3 which applies accordingly. Supplementary or deviating applies on the basis of the same reference numbers:

The servomotors 15 to 20 (six in number) are arranged to move the total of six healds 2 associated with the servomotor group 13, again below them, but they are not arranged in a circle but on an elliptical figure 33a. The inner ends of the levers 21 to 26, which are connected to the connecting rods 34 to 39, are located in the center of this ellipse. The ellipse 33 a is oriented so that its large semi-axis lies on the vertical 41. The ends of the levers 21 to 26 are preferably arranged in a region between the two focal points of the ellipse 33a. The connecting rods 34 to 39 have correspondingly different lengths. The Pleuellängenunterschiede are however small. Preferably, they are less than the focal distance of the ellipse 33a. Preferably, the levers 21 to 26 are equal to each other. The included with the connecting rods 34 to 39 angles are preferably not less than 45 °.

Accordingly, the remaining servo motor groups 14, 13 ', 14' are constructed. It can be a drive device according to FIG. 4 are used, the characteristic blocks 57 to 59 are adapted accordingly. The axes of rotation 27 to 32 of the servomotors can be arranged both on the ellipse 33a and on circular arcs with a correspondingly large diameter. In any case, they set an isosceles, relatively flat triangle on either side of the vertical 41.

A further modification of the above-described embodiments may relate to the control device 43:

FIG. 9 illustrates the modified controller 43 'which does not include characteristic blocks. Instead of the characteristic blocks 57 to 59, switch blocks 57 'to 59' are provided which obtain a switching signal from the instructions pending at the inputs 61, 62, 63. A first value of the respective input signal corresponds to a first rotation angle, for example for a lower position of the respective shaft 3, 4, 5. A second value of the input signal at the control inputs 61 to 63 corresponds to a second rotational position of the respective servomotor 15 to 17 for a second one Position of the connected shaft 3, 4, 5. The angle values are dimensioned so that, given the gear ratio formed by the levers 21 to 23 and the connected connecting rods 34 to 36, the respective desired working positions for the connected shaft 3, 4, 5 are achieved. When the input signals to the control inputs 61 to 63 are constant, the respective switch block 57 'to 59' outputs a constant angle command value which the servomotors 15 to 17 assume. If the control signals at the control inputs 61 to 63 change in such a way that the respective switch block 57 'to 59' specifies another angle preset value at its output, the position control loops 51 to 53 immediately determine a corresponding control deviation and execute the servomotors 15 to 17 as fast as possible possible after to eliminate the control deviation.

In a further modification of the control device 43 or 43 ', the characteristic blocks 57 to 59 or the switch blocks 57' to 59 'can also be used in the signal lines 48 to 50 in order to compensate for the transmission nonlinearity there. All the described control devices 43 can be realized both in terms of hardware technology and by corresponding program blocks in conjunction with a suitable computer, for example a microcontroller.

A shed forming device 1 for a weaving machine has a plurality of heald frames, to which a drive device with a plurality of servomotor groups 13, 14 is assigned. The servomotor groups are arranged below the healds 3 to 8 in each case as a cluster, wherein they are arranged with their axes of rotation 27 to 32 on a circle, an ellipse or a similar figure. In addition, they are axially offset from each other. Each servomotor is 15 to 20 added. Each servo motor 15 to 20 is provided with a driven lever 21 to 26. The free ends of all levers are approximately in the center of the circle or the ellipse or other circulating figure. They are connected by connecting rods 34 to 39 with the heddles 3 to 8, wherein they include different angles with the connecting rods 34 to 39. This results in a drive device with low inertia, low compliance and low clearance. It is the controlled achievement of very fast shaft movements possible.

LIST OF REFERENCE NUMBERS

1

Shedding arrangement

2, 3, 4, 5, 6, 7, 8 3 ', 4', 5 ', 6', 7 ', 8'

heald

9

strands

11

eyelet

12

driving means

13, 14, 13 ', 14'

Servo motor groups

15, 16, 17, 18, 19, 20

servomotors

21, 22, 23, 24, 25, 26

lever

27, 28, 29, 30, 31, 32

axis of rotation

33

circle

33a

ellipse

34, 35, 36, 37, 38, 39

pleuel

41

vertical

42

horizontal

43

control device

45, 46, 47

trunk group

48, 49, 50

signal lines

51, 52, 53

Position control loop

54, 55, 56

Setpoint programming input

57, 58, 59

Characteristic blocks

61, 62, 63

control inputs

Claims (22)

1. Shedding device (1) for a loom,
   with a plurality of heald shafts (3, 4, 5, 6, 7, 8), which are arranged adjacent to one another according to a predetermined graduation and are disposed to be displaceable in one direction (41) in order to be moved out of a resting position for shedding,
   with a drive means (12), which has a plurality of servomotors (15, 16, 17, 18, 19, 20) individually associated with the heald shafts (3, 4, 5, 6, 7, 8), the drive shaft of said servomotors, which is rotatable around a rotational axis (27, 28, 29, 30, 31, 32), respectively bearing a lever (21, 22, 23, 24, 25, 26), which is connected to the heald shaft (3, 4, 5, 6, 7, 8) by means of a connecting rod (34, 35, 36, 37, 38, 39), wherein the levers (21, 22, 23, 24, 25, 26) are oriented in different spatial directions at least when the shafts (3, 4, 5, 6, 7, 8) are located in the resting position,
   characterised in that
   the levers (21, 22, 23, 24, 25, 26) enclose different angles with the connecting rods (34, 35, 36, 37, 38, 39) at least when the shafts (3, 4, 5, 6, 7, 8) are located in the resting position.
2. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) are arranged one above the other in at least three planes.
3. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) are offset axially relative to one another.
4. Shedding device according to claim 1, characterised in that the servomotors (12?, 16, 17, 18, 19, 20) form a servomotor group (13) and that the rotational axes (27, 28, 29, 30, 31, 32) of servomotors (15, 16, 17, 18, 19, 20) arranged one above the other define a triangle.
5. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) form a servomotor group (13, 14) and that the rotational axes (27, 28, 29, 30, 31, 32) of the servomotors (15, 16, 17, 18, 19, 20) are arranged on a common circle (33).
6. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) form a servomotor group (13, 14) and that the rotational axes (27, 28, 29, 30, 31, 32) of the servomotors (15, 16, 17, 18, 19, 20) are arranged on an upright ellipse (33a).
7. Shedding device according to claim 1, characterised in that the servomotors (15,16, 17, 18, 19, 20) form a servomotor group (13, 14) and that the levers (21, 22, 23, 24, 25, 26) of the servomotors (15, 16, 17, 18, 19, 20) stand in a common centre when the heald shafts (3, 4, 5, 6, 7, 8) are located in the resting position.
8. Shedding device according to claim 1, characterised in that all the connecting rods (34, 35, 36, 37, 38, 39) of the drive means (12) are of equal length.
9. Shedding device according to claim 1, characterised in that the connecting rods (34, 35, 36, 37, 38, 39) of the drive means (12) are of different lengths, wherein the differences in length are smaller than the vertical spacings between the servomotors (15, 16, 17, 18, 19, 20).
10. Shedding device according to claim 1, characterised in that the levers (21, 22, 23, 24, 25, 26) are of equal length.
11. Shedding device according to claim 1, characterised in that two servomotors (15, 16, 17, 18, 19, 20) are respectively associated with each heald shaft (3, 4, 5, 6, 7, 8).
12. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) form at least two servomotor groups (13, 14) and that a servomotor (15, 16, 17, 18, 19, 20) from each servomotor group (13, 14) is associated with each heald shaft (3, 4, 5, 6, 7, 8).
13. Shedding device according to claim 1, characterised in that the connecting rods (34, 35, 36, 37, 38, 39) are articulated directly to the heald shafts (3, 4, 5, 6, 7, 8).
14. Shedding device according to claim 1, characterised in that the heald shafts (3, 4, 5, 6, 7, 8) are rigidly connected to intermediate elements, on which articulations are provided for connection of the connecting rods (34, 35, 36, 37, 38, 39).
15. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) are connected to a control means (43), which is connected to a machine control system of the loom.
16. Shedding device according to claim 1, characterised in that the servomotors (15, 16, 17, 18, 19, 20) are connected to a control means (43), which is part of a machine control system of the loom.
17. Shedding device according to claim 15 or 16, characterised in that for each servomotor (15, 16, 17, 18, 19, 20) the control means (43) has a control input (61, 62, 63) for a control signal.
18. Shedding device according to claim 15, 16 or 17, characterised in that for each servomotor the control means (43) has a block of characteristics (57, 58, 59), which represents a correlation between the angle of rotation of the servomotor (15, 16, 17, 18, 19, 20) and the path covered by the heald shaft (3, 4, 5, 6, 7, 8).
19. Shedding device according to claim 17, characterised in that the control signal is a switching signal and when this is received the servomotor (15, 16, 17, 18, 19, 20) is actuated so that the heald shaft (3, 4, 5, 6, 7, 8) performs a stroke.
20. Shedding device according to claim 19, characterised in that the shaft acceleration, shaft speed and shaft braking are adjustable.
21. Shedding device according to claim 17, characterised in that the control signal is a guidance signal, which can assume different values, wherein each value of the control signal corresponds to a position of the heald shaft (3, 4, 5, 6, 7, 8).
22. Loom with shedding device according to one or more of claims 1 to 21.

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