EP0526390B1 - Gripper loom with an insert device which is adjustable according to the thread properties - Google Patents

Description

The invention relates to a method for operating a rapier weaving machine according to the preamble of claim 1 and a rapier weaving machine.

From the publications FR-A 2 381 850 and GB-A 2 085 039 rapier weaving machines are known in which the rapier and rapier grippers are driven by program-controlled servomotors. DE-A 3 224 708 discloses a rapier weaving machine with a clamp opener in the center. These clamp openers are operated via shafts and cams that are driven by the main drive of the weaving machine.

In certain rapier weaving machines, the rapier movement is generated by means of flexible belts and oscillating belt wheels, the belt wheel drive being coupled to the main shaft and using so-called space crank drives (see DE-PS 3029642 = MR 170). The hook heads have wedge clamps for the weft thread, with which the thread can be picked up automatically at the entrance to the compartment (by the rapier gripper) or in the middle (by the rapier gripper) without the clamps having to be actuated. The existing actuation levers for opening the thread clamps are used to open the clamps at the reversal points of the hook heads outside the compartment by means of overrun cams, in order to be able to remove stuck fibers, for example with blow nozzles (for the holster gripper also to release the weft thread).

The automatically acting thread clamps of the rapier heads mean an advantageous simplicity of the rapier weaving machines; however, there is a certain susceptibility to faults depending on the type of yarn. For example, if a heavy, stiff yarn is woven in, there is a risk that the thread transfer from the bringer to the hauler fails. When the thread is transferred, the grippers experience maximum acceleration in the extension direction due to the drive by the space crank mechanism, and thus maximum force of inertia acts on the weft gripper's weft yarn. After the reversal point when the rapier gripper retracts, this inertia force is opposite to the direction of movement and this can lead to the weft yarn sliding out of the thread clamp before being picked up by the rapier gripper and thus no longer being able to be transferred. If you want to remedy this problem by increasing the clamping force of the bringer thread clamp, you are dealing with a new problem. In this case, it can happen that the yarn is damaged - for example torn - when it is pulled out of the bringer by the puller with a force that is inevitably increased in accordance with the greater clamping force.

The problem described also applies to weaving machines with bar grippers. The invention therefore also relates to such weaving machines.

It is an object of the invention to improve the operating method for the rapier weaving machines defined above in such a way that the thread takeover by the holer rapier can be carried out with greater reliability in the center of the compartment, this working step being coordinated with the type of weft thread used and also with the clamping action of the rapier clamps got to. According to the invention, this object is achieved by the method defined in claim 1.

By replacing the space crank drive for the band wheel drive (or rod drive) with a servomotor, one gains new degrees of freedom that make it possible Gripper movements better to adapt the thread take-up or thread transfer conditions. In addition, the peculiarities of the different weft yarns can be individually taken into account by means of program-controlled servomotors by coordinating the movements of the grippers with the weft yarn to be entered. This makes it possible, for example, to reduce the inertial forces during thread transfer while the speed of the weaving machine remains unchanged. In addition, in the event of a change in the fabric width, the adaptation of the gripper strokes is very simplified, since this can be carried out by adapting the program of the control logic.

By providing the clamp openers according to the invention in the middle of the compartment at the thread transfer point, further degrees of freedom are gained. The clamping force of the thread clamp can thus be specified to a greater extent, since a forced loosening of the thread clamp by the clamp opener now prevents damage to the weft yarn during takeover. The use of terminal openers is known per se (see for example DE-OS 3224708). In contrast to the known ones, the clamp opener according to the invention is driven by a servomotor in a program-controlled manner. Among other things, this has the advantage that the terminal opener can be individually, i.e. can be adjusted to the individual type of thread or "weft color". Under certain circumstances, actuation of the clamp opener can only be provided for individual shot colors.

Both measures according to the invention, namely belt drive (or rod drive) by servomotors or clamp openers also with servomotors, when used individually mean a possible improvement in the weft insertion. The combination of both measures results in a particularly advantageous weft insertion device. For the servomotors of the gripper drives are preferably highly dynamic Servomotors used. Such servomotors are characterized by the fact that they can be used in a program-controlled manner similar to stepper motors, but that, in contrast to stepper motors, they have much higher torques (around 300 Nm) at the speeds typical for rapier weaving machines (around 500 min ^-1 ) and weaving widths (around 2 m ) can deliver.

Fig. 1a

zwei Greiferköpfe kurz vor dem Zusammentreffen in der Fachmitte, wobei für den Bringergreifer die Unterseite anhand eines Spiegelbildes sichtbar gemacht ist und beim Holergreifer lediglich die Kopfspitze dargestellt ist,

Fig. 1b

den Holergreifer der Fig.1a nach der Fadenübernahme,

Fig. 2

einen bekannten Antrieb eines Bandrades unter Verwendung eines Raumkurbeltriebs,

Fig. 3

den erfindungsgemässen Antrieb eines Bandrades unter Verwendung eines Stellmotors,

Fig. 4

ein Diagramm der Greiferbewegung bei Verwendung eines Raumkurbeltriebs, wobei die Bewegungen der beiden Greifer "phasengleich" sind,

Fig. 5

einen vergrösserten Ausschnitt aus dem Diagramm der Fig.4,

Fig. 6

einen entsprechenden Ausschnitt wie in Fig.5 für eine "phasenverschobene" Greiferbewegung,

Fig. 7

eine perspektivische Darstellung einer erfindungsgemässen Klemmenöffnervorrichtung,

Fig. 8

einen Diagrammausschnitt, entsprechend Fig.5, für ein erstes Ausführungsbeispiel der Erfindung,

Fig. 9

eine entsprechende Darstellung für ein zweites Ausführungsbeispiel und

Fig.10

ein Diagramm mit asymmetrischer Greiferbewegung.

The invention is explained in more detail below with reference to drawings and diagrams. Show it:

Fig. 1a

two gripper heads shortly before they meet in the center of the compartment, the underside being made visible to the bring gripper by means of a mirror image and only the tip of the head being shown for the grab gripper,

Fig. 1b

the Holergripper of Fig.1a after thread takeover,

Fig. 2

a known drive of a belt wheel using a space crank drive,

Fig. 3

the drive according to the invention of a belt wheel using a servomotor,

Fig. 4

2 shows a diagram of the gripper movement when using a space crank drive, the movements of the two grippers being "in phase",

Fig. 5

3 shows an enlarged section from the diagram in FIG. 4,

Fig. 6

a corresponding section as in FIG. 5 for a "phase-shifted" gripper movement,

Fig. 7

2 shows a perspective illustration of a clamp opening device according to the invention,

Fig. 8

5 shows a diagram section, corresponding to FIG. 5, for a first exemplary embodiment of the invention,

Fig. 9

a corresponding representation for a second embodiment and

Fig. 10

a diagram with asymmetrical gripper movement.

The two rapiers, namely the rapier rapier 1 with the weft thread 3 and the rapier rapier 2, move towards one another in accordance with the arrows B and H in FIG. Based on the mirror image 1 'of the bringer gripper 1 you can see how the mirrored weft 3' is held by the wedge clamp, which is formed by the two legs 11 'and 12', at the clamping point 31 '(or 31). The clamp leg 11 'is resilient, so that by pressing the actuating lever 13' (or 13), which is connected to the clamp leg 11 ', the thread clamp can be opened. The mirror 9 is, of course, arranged below the carrier gripper 1 for illustration purposes only.

The gripper 1 is moved by the flexible belt 4 (mirror image 4 '). When the thread is picked up, the picker 2 is inserted into the picker so far that the hook-shaped tip 22 of the picker 2 can grip the weft thread 3 when it is pulled back (arrow G).

As shown in FIG. 1b, the weft thread 3 is held at the clamping point 32 by the wedge clamp formed from the hook 22 and the movable clamping part 21. The wedge clamp is opened outside the shed and by pressing the actuating lever 23 and by means of the indicated mechanism 24, by means of which the clamping part 21 is withdrawn.

In FIG. 2, the drive of the oscillating movement (double arrow A), which is generated by means of the belt 4, the belt wheel 41 and the space crank drive 50, is shown for the gripper 1. The drive shaft 501 rotates at a constant angular velocity, which is transmitted by the space crank drive 50 into an oscillating pivoting movement of the toothed segment 502 and of the belt wheel 41 - via the toothed wheel 42. 3 shows the servomotor 5, which according to the invention replaces the space crank mechanism 50, the pinion 52 taking the place of the toothed segment 502. The drive energy and the control signals for the servomotor 5 are supplied via the cable 51. The servomotor 5 can of course also be connected directly to the belt wheel without an intermediate gear.

The diagram of FIG. 4 shows the working phase of the weaving machine on the downward ordinate. As usual, this work phase is related to the angular position of the main shaft and expressed by machine degree (MGR). The 0 ° position, ie the start of the machine cycle, is the gripper reversal point outside the compartment in the present example. The abscissa of the diagram indicates the positions of the gripper heads, more precisely of the clamping points 31 and 32 (see FIGS. 1a, b). The weave or compartment width is indicated by the double arrow W. The two cosine-shaped curves 10 and 20 represent the gripper movements over a machine cycle, as are generated by means of space crank drives. The transfer of the weft thread from the rapier gripper 1 (curve 10) to the holder gripper 2 (curve 20) takes place within the dash-dot circle 91 at 180 MGR, the weft thread starting at point 30 with the Holger gripper is carried. The tracks 10 and 20 of the clamping points 31 and 32 in the inner region of the circle 91 are shown enlarged in FIG. There the horizontal bar (10 mm) and the vertical bar (10 ° = 10 MGR) give an impression of the scale in the magnification.

While FIGS. 4 and 5 represent "in-phase" gripper movements, FIG. 6 shows the conditions for a "phase-shifted" gripper movement, in which the point of reversal of the gripper gripper follows approximately 10 MGR after that of the Holger gripper. The shot transfer is "flying" as in a relay race: Before the "change of hand" at point 30, the two gripper heads move briefly in the same direction, the holer gripper (curve 20) with increasing and the bringer gripper (curve 10) with decreasing speed, wherein the point gripper reaches its turning point at point 30 and is therefore currently stationary (although at the same time a maximum acceleration force is exerted on the ring gripper in the extension direction). This transfer method is preferred for yarns with low tensile strength.

In a first exemplary embodiment of the invention, in which the belt wheel of the carrier gripper is driven by a program-controlled servomotor and a clamp opener 6 according to FIG. 7 is assigned to the carrier gripper at the transfer point in the center, the conditions shown in FIG. 8 can be brought about. There is a similarity to the "phase-shifted" gripper movement in FIG. 6, with the difference that when the thread is transferred the carrier gripper is at rest over an interval of, for example, 20 MGR and that during this standstill phase the carrier thread clamp is actuated by the clamp opener 6. The interval within which the opening and subsequent closing of the Bringer thread clamp take place, is symbolized in Figure 8 by the lenticular mark 601. The advantage of forcing the thread clamp to open has already been explained.

7 shows an example of a clamp opener 6 according to the invention. It is arranged in the weaving machine under the fabric web in the area of the center of the compartment at the transfer point of the weft thread. The control lever 61 is moved by the servomotor 62 via the gear arranged in the housing 63, which consists of the two gear wheels 64a and 64b, and the coupling 65. Some bearings, which are arranged in or on the wall of the housing 63, are indicated by cylinders 66a, 66b and 66c. The gooseneck-shaped control lever 61, which is in the rest position in FIG. 7, must be short and stiff so that it can open the thread clamp of the associated hook as free of vibrations as possible so as not to cause any damaging effect on the weft thread. The control lever 61 is aligned parallel to the warp threads of the shed (not shown). Its head part with the push part 610 must be narrow so that it can be gently pivoted into the shed between the warp threads (double arrow S). The working position 61 'of the control lever 61 is indicated by dash-dotted lines in Figure 7. With a small, downward swiveling movement, the control lever in the working position 61 'can press the operating lever of the hook thread clamp.

In contrast to the known clamp openers (DE-OS 3224708), the clamp opener 6 according to the invention can be made more space-saving. This is very important, since the spatial conditions in a weaving machine below the fabric web are mostly unfavorable and do not allow the known devices to be realized. By using an intermediate gearbox similar to that of the No servomotor for the belt wheel drive, an even more compact clamp opener can be constructed.

For a second exemplary embodiment of the invention, in which the belt wheels of both grippers are driven by program-controlled servomotors and both grippers are assigned clamp openers 6 according to the invention, the relationships shown in FIG. 9 can be realized. Before the thread transfer, both hook heads reach their reversed positions practically simultaneously, where they each briefly remain in a standstill phase (curve sections 10a and 20a). First the holer thread clamp is opened (interval 602) and the bring gripper makes a small retraction movement, whereby the weft thread slides into the open thread clamp of the holer gripper. In a second standstill phase of the bring gripper (curve piece 10b), the bring thread clamp is opened (interval 601), so that the still standing grab gripper, whose thread clamp is now closed, can pull the weft thread out of the bring thread clamp and then take it with it during its retraction movement. After closing the bringer thread clamp, the retractor movement can also be carried out for the bringer gripper.

The grippers and in particular their thread clamps can be modified in such a way that the clamp openers according to the invention can act on them while the grippers are moving. In such a modification, the actuating levers of the thread clamps have rollers or sliding surfaces, for example. In this case, it is no longer necessary for the grippers to come to a standstill when the thread clamps are forced to operate by the clamp openers.

When using clamp openers according to the invention, the automatic operation of the wedge clamps can be dispensed with in the thread clamps. But if, like the first embodiment, only the clamp gripper is assigned a clamp opener, the holer gripper should continue to have a wedge clamp.

The belt wheel drive by servomotors can also be used in an advantageous manner during phases other than the thread transfer between the two grippers: When the weft thread is taken over by the rapier gripper at the entrance to the compartment, there is a particular susceptibility to faults, since "carry-along errors" can occur there. The frequency of carry-on errors can be reduced by a programmed slowdown or even a brief standstill of the handler at the entrance to the compartment.

As illustrated by FIG. 10, an asymmetrical course of the gripper movement can also be generated by means of the band wheel drive by servomotors. The dot-dash line in Fig. 10 shows the symmetrical course for the phase-shifted gripper movement (see Fig. 6). The solid curves represent the example of an asymmetrical gripper movement: The thread transfer is "off-center" at line 96, which is shifted towards the bringer side with respect to the center line 95, where the thread transfer takes place in the symmetrical case. (The center area of the diagram is not drawn to scale in order to be able to show the thread transfer, in particular the thread take-over by the picker, more clearly.) As can be seen from a comparison with the dash-dotted curves, the retracting movement (curve piece 101) is slower for the carrier gripper than the extension movement (curve piece 102). The reverse is the case with the Holer gripper (curve sections 201 or 202). This is an advantage because during the slower movement the two bringers each carry the weft thread and the forces exerted on the weft thread are lower.

Rapier weaving machines with the belt wheel drives according to the invention and the clamp openers according to the invention, with highly dynamic servomotors in particular being used for the servomotors, are particularly suitable if the weaving machines are used by means of control technology, i.e. central computer control.

Claims (8)

1. A method of operating a gripper loom in which a giver gripper and a taker gripper oscillate synchronously and to opposite hands, wherein the giver gripper is driven by a programmed adjusting motor, characterised in that the giver gripper is changed over into a stationary phase at yarn transfer in the centre of the shed, in that during this stationary phase the clamp of the giver gripper is actuated by a programmed clamp opener and in that the taker gripper removes the weft yarn from the actuated clamp of the giver gripper, the programming parameters of the clamp opener being devised in dependence upon the properties of the weft yarns (3) used and of the gripper clamp.
2. A method according to claim 1, characterised in that at least the taker gripper (2) has a wedge clamp and in that the same takes over the weft yarn automatically.
3. A method according to claim 1, characterised in that the taker gripper is also driven by a programmed adjusting motor, in that at yarn transfer and before the stationary phase of the giver gripper the taker gripper is changed over into a stationary phase and its clamp is opened by a clamp opener, in that the giver gripper moves the weft yarn into the opened clamp of the taker gripper, and in that the clamp of the taker gripper then closes during the stationary phase of the giver gripper and the taker gripper removes the weft yarn from the actuated clamp of the giver gripper.
4. A method according to claim 3, characterised in that both the grippers (1, 2) are stopped during the opening of the giver gripper (1) at yarn transfer.
5. A method according to claim 3 or 4, characterised in that the giver gripper starts to open during the closing of the taker gripper.
6. A method according to any of claims 1 to 4, characterised in that the or each clamp opener is driven by a programmed adjusting motor.
7. A loom for performing the method according to claim 6 comprising a giver gripper (1), a taker gripper (2) and at least one programmed clamp opener (6) drivable by an adjusting motor and disposed near the central zone of the shed and associated with the giver gripper, the gripper heads having actuating levers (13, 21 respectively) for opening yarn clamps, at least the giver gripper being drivable by a programmed adjusting motor (5), wherein the or each clamp opener (6) is a device comprising gearing consisting of two gearwheels (64a, 64b) of different sizes, the small gearwheel (64b) being drivable by the associated adjusting motor and the large gearwheel (64a) being connected by way of a link (65) to a control lever (61) for actuating the gripper associated with the clamp opener.
8. A loom according to claim 7, characterised in that the adjusting motor (5) for at least one of the gripper drives is a highly dynamic servomotor.

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