EP1874987B1 - Jacquard machine comprising a bistable element which is used to lift and lower warp threads - Google Patents

Abstract

The jacquard machine for use in a weaving loom with lifters (2) of the lifting and lowering of warp threads (3) of the weaving loom, has a bi-stable element (1) connected to the drive for each lifter and which on both sides is rigidly clamped in a holder (5a,5b) by its end sections (1a,1b), wherein the deformation of the element is achieved by the bringing together of the two end sections. The bi-stable element is formed by an elastically deformable bar or an elastically deformable leaf spring.

Description

The present invention relates to a jacquard machine according to the preamble of claim 1, which does not require the use of urine cords and for this purpose has a bistable element which can be deformed for raising or lowering the warp threads of a loom.

A generic jacquard machine is for example from the DE 43 35 620 A1 the applicant known. In this case, a flat bar used as a bistable element is caused to oscillate by the action of external force, whereby a corresponding raising or lowering of a warp thread held by the board takes place via a board connected to the flat bar. This is a further development of classic jacquard machines, in which usually the boards by means of driven knives perform a shed-forming lifting and lowering movement. Via a board selection device, depending on the weave pattern to be woven, certain boards can be selected which are separated from the driven blades and thus do not participate in the lifting and lowering movement. Usually, the so-called. Rapportierung the weave pattern by means of a variety of Harnschnüren that allow a formschlüßige connection between the boards and the warp threads during the lowering. In this case, one warp thread of the weaving pattern is connected to one board each via a harness cord. To produce the frictional connection during the lowering movement, tension springs are generally provided on the ends of the harness cords opposite the sinkers.

By in the DE 43 35 620 A1 described further development of conventional Jacquard machines can be dispensed with the use of these tension springs and the urine cords, which brings a great advantage in terms of reliability of the entire system with it. Since the urine cords are subject to great wear, longer production downtime, which is often required to replace broken cords, can be avoided.

It has now been shown in practice that for the realization of in the DE 43 35 620 A1 described concept the bistable element in very special Fashion must be designed. The flat bar is subjected to specific physical and mechanical requirements during deformation, which must be taken into account in the design of the bar. In order to ensure a smooth flow during the subsequent operation, a particularly high cost in the design of the bistable element is required, which in turn leads to an increase in the manufacturing cost.

Accordingly, the present invention is based on the object, which in the DE 43 35 620 A1 described concept for designing a jacquard machine such that the raising and lowering of warp of a loom by means of the deformation of a bistable element can be achieved in a simple and reliable manner. It should also be taken into account in particular that the effort for the realization of a bistable element should be kept within a reasonable range.

The object is achieved by the invention specified in the independent claims. Advantageous developments of the invention are the subject of the dependent claims.

The DE 43 35 620 A1 describes a concept which relates primarily to the mounting of the bistable element during operation of the jacquard machine. Thus, it is provided in the prior art to rotatably connect the bistable element at two bearing points with corresponding brackets, wherein the deformation of the element is achieved by merging the bearing points. According to the present invention, on the other hand, it is proposed to modify the mounting of the bistable element in such a way that it is now firmly clamped on both sides with its end regions in a holder, the deformation of the element being achieved by merging the two end regions. As will be explained in detail later, resulting from this novel way of holding the bistable element in practice significant advantages, despite all the desired effect, namely the targeted deformation of the bistable element for raising or lowering a warp thread is reliably achieved.

According to the first aspect of the present invention, there is thus proposed a jacquard machine for use in a loom, which has boards for raising and lowering warp yarns of the loom, a board driving means for effecting a lifting or lowering movement of the boards, and a board selecting device which includes certain of Selects boards to hold the warp threads connected to the respective boards in an elevated or lowered state, the board drive means for each board having a bistable connected thereto, which alternately by an axially acting on the element or in the longitudinal direction outer deformation stress first stable position state, which corresponds to a raised state of the board, or a second stable state, which corresponds to a lowered state of the board occupies, and according to the invention, the bistable element is firmly clamped on both sides with its end portions in a holder and the deformation of the element by Merging the two end portions is achieved.

An erfmdungsgemäßer aspect relates to the design of the bistable element itself. While it is provided in the prior art to use a single flat bar or a single leaf spring, it is proposed according to the invention to design the bistable element multi-layered and this to arrange a plurality of elastically deformable rods or leaf springs on top of each other ,

Accordingly, in accordance with this aspect of the present invention, there is provided a jacquard machine for use in a loom, comprising boards for raising and lowering warp yarns of the loom, board driving means for effecting a raising or lowering movement of the boards, and a board selecting device which selects particular ones of the boards; in order to hold the warp threads connected to the boards concerned in an elevated or lowered state, wherein the board drive device for each board has a bistable element connected thereto, which alternately a first stable position state by an axially or longitudinally acting on the element outer deformation stress , which corresponds to a raised state of the board, or a second stable state, which corresponds to a lowered state of the board, occupies, and according to the invention, the bistable element by a multilayer ela is formed deformable rod or a multi-layer elastically deformable leaf spring with a plurality of superposed rods or springs. Due to the multilayer design of the bistable element, the physical and mechanical requirements of this can be realized much better and in particular also easier. In this case, it is also possible, in particular, to suitably adjust its properties by selecting the material for the various layers. In the same way it would be also possible to form all layers of the same material, which then has to be selected accordingly.

Both addressed aspects of the invention can be advantageously combined to arrive at a particularly effective Jacquard machine. However, it would also be possible to use the individual ideas of the invention individually. Every thought taken alone contributes to a significant improvement in the effectiveness and reliability of a jacquard machine.

The storage of the bistable element can be chosen such that when the mechanical deformation stress is exerted, one of the two of the stable position states is reached and the bistable element assumes a neutral state without the action of the mechanical deformation stress. In this case, an initial device can then be provided which, in response to a control signal, effects a directed initial deflection of the bistable element from its neutral position state, such that the element assumes a specific one of the two stable position states after the deformation stress has been applied. This initial device can be formed, for example, by a pair of electromagnets or a hydraulic or pneumatic piston coupled to the bistable element. Furthermore, the jacquard machine according to the invention may have, in the vicinity of the bistable element, sensor elements with the aid of which the current positional state of the element is detected. In this way, a safe control of the bistable element in the desired position is possible.

• Fig. 1 ein erstes Ausführungsbeispiel der Lagerung und Ansteuerung eines bistabilen Elements bei einer Jacquardmaschine gemäß der vorliegenden Erfindung;
• Fig. 2 ein zweites Ausführungsbeispiel für die Lagerung und Ansteuerung eines bistabilen Elements;
• Fig. 3 eine vergrößerte Darstellung der Anordnung des bistabilen Elements gemäß der vorliegenden Erfindung;
• Fig. 3a einen vergrößerten Ausschnitt der Fig. 3;
• Fig. 4 eine Darstellung der Lagerung eines bistabilen Elements entsprechend dem Stand der Technik und
• Fig. 4a eine vergrößerte Darstellung von Fig. 4.

The invention will be explained in more detail with reference to the accompanying drawings. Show it:

• Fig. 1 a first embodiment of the storage and control of a bistable element in a jacquard machine according to the present invention;
• Fig. 2 a second embodiment for the storage and control of a bistable element;
• Fig. 3 an enlarged view of the arrangement of the bistable element according to the present invention;
• Fig. 3a an enlarged section of the Fig. 3 ;
• Fig. 4 a representation of the storage of a bistable element according to the prior art and
• Fig. 4a an enlarged view of Fig. 4 ,

As already mentioned, the present invention represents a further development of a jacquard machine which comprises the DE 43 35 620 A1 is known. For additional explanation with regard to the basic mode of operation of this machine, reference is again expressly made to this publication at this point. Fig. 1 shows a first embodiment of the board drive in the jacquard machine according to the present invention, wherein only the arrangement for a single board is shown. According to the number of boards used in a complete jacquard machine, this arrangement accordingly exists multiple times, the board drive devices are then arranged to operate a plurality of offset in the direction of the warp threads arranged boards cascade.

In the Fig. 1 illustrated board drive has as a central element to a bistable element 1 in the form of an elastically deformable rod or an elastically deformable leaf spring. By means of a suitable storage and control arrangement, whose configuration will be explained in detail later, the bistable element 1 can be placed in two different position states. In this case, a first positional state is illustrated by a solid line, whereas a second positional state is illustrated by the dotted line. With the bistable element 1, a circuit board 2 is mounted, which is non-positively and positively connected in its upper end portion 2a with the bistable element 1. In the lower part of the board 2 is an eyelet 2b for carrying a warp thread 3 of a loom. Depending on the deformation of the bistable element 1 in one of the two states, the circuit board 2 and hence the warp thread 3 are thus in a raised or lowered position. Alternatively to the illustrated embodiment, it would also be conceivable to provide on the underside of the board 2 a fastening device for a strand or the same, via which the connection between the warp thread 3 and the board 2 takes place.

The deformation of the bistable element 1 in one of the two illustrated states of the state takes place in a known manner in that the bistable element 1 is loaded with a deformation stress acting axially or in the longitudinal direction on the bistable element 1. This is done by a hydraulic device, which two holders 5a and 5b for supporting the end portions 1a and 1b of having bistable element 1, wherein the position of the two holders 5a and 5b by means of two hydraulic cylinders 6a and 6b can be changed. So as to load the bistable element 1 with a deformation stress, the two brackets 5a and 5b are moved towards each other, to relieve the bistable element 1, the brackets 5a and 5b are removed from each other. The principle of deformation of the bistable element 1 is the same as in the DE 43 35 620 A1 , After loading the element 1 with the deformation stress, this therefore assumes one of the two position states, wherein the decision as to which position is taken depends on the initial conditions before the axial load is exerted. For targeted modification of these initial conditions can be provided an Intialvorrichtung whose operation will be explained later.

If the warp thread connected to the board 2 is now to change from the raised to the lowered position or vice versa owing to the weaving pattern to be woven, then the bistable element 1 is first relieved of load, this being then due to the elastic deformation together with the board 2 in the direction of the other stable situation is accelerated. As a result of the kinetic energy present in the neutral position, that is to say in the extended state of the bistable element 1, the dead point located there is overcome and the element 1 is deformed at least slightly in the direction of the respective other stable positional state. In this movement phase, the load of the bistable element 1 caused by the hydraulic cylinders 6a and 6b sets in again, so that it finally becomes deformed in such a way that it assumes the desired other stable positional state.

As a result of this movement, the board 2 and the warp thread 3 connected thereto are transferred from the raised to the lowered state or vice versa. By means of a suitable control of the hydraulic cylinders 6a and 6b, the warp thread 3 can be brought into a position corresponding to the pattern to be woven in this manner.

Before discussing the operation of the already mentioned initial device, the inventive feature of the illustrated device will first be explained. This consists on the one hand in the embodiment of the bistable element 1 and the other in the same storage. Initially, the inventive storage of the bistable element 1 is characterized by the fact that this is now clamped with its end portions 1a and 1b firmly in the corresponding brackets 5a and 5b. The resulting special features will be described below with reference to Figures 3, 3a, 4 and 4a be explained. The FIGS. 3 and 3a show the arrangement or deformation of the bistable element 1 in a storage according to the present invention, while the FIGS. 4 and 4a Comparable representations in a holder, as in the DE 43 35 620 A1 is intended to show.

The difference in the two types of storage leads, as can be seen from the illustrations, to a completely different deformation of the bistable element 1. While in the prior art FIG. 4 was provided that the element to be deformed 1 was connected at its two ends via joints with corresponding brackets, the end portions 1a and 1b in the in FIG. 3 clamped illustrated case of the invention. This results in two different types of deformation of the bistable element 1, which have already been studied by the mathematician and physicist Euler. According to its findings, a distinction is made between four so-called kinks, wherein the arrangement in FIG. 4 according to the prior art, the second Euler buckling case and the inventive arrangement according to FIG. 3 corresponds to the fourth Euler kink case. These lead to two completely different bending lines of the bistable element 1, which is readily apparent. An essential difference here is that according to the state of the art FIG. 4 gives a bending line corresponding to a half sinusoidal line, whereas in the arrangement according to the present invention, a bending line corresponding to a complete phase of a sine curve results. However, the deflection h of the bistable element with respect to a stretched arrangement is the same despite everything, so that the circuit board 2 connected to the bistable element 1 and thus the warp thread 3 can still be deflected in the desired manner.

The bending equations resulting for both storage cases and examined by Euler also show that the same parameters for the bistable element 1 give different sizes. For example, the buckling load for the bistable element 1 in the case according to the invention is four times as high as in the case of storage according to the prior art. By changing the corresponding parameters (eg the moment of inertia), however, the buckling load or any other arbitrary variable can be set in the same way in both cases. With regard to the possibilities for using the bistable element 1 for the suitable control of the warp thread, the same advantages are still obtained.

However, an advantage resulting from the storage according to the invention consists in that now improved possibilities for the realization of the bistable element 1 exist. It has been shown that the realization of the bistable Elements 1 with the help of single bars or individual leaf springs is difficult. According to the second aspect of the present invention, it is accordingly provided that the bistable element 1 is not formed by a single component but by a plurality of bars arranged on top of each other. Like the enlarged view of the end area in FIG. 3a can be removed, now results in the holder according to the invention the advantage that the end portions 100a of the individual layers 100 of the bistable element 1 are basically aligned parallel to each other, both in the stretched as well as in the deformed or kinked state. This is achieved by the deformation of the bistable element 1 in the form of a complete sine curve, since any relative displacement between the individual layers in one half of the bending line in the other half of the bending line is compensated again. This circumstance greatly facilitates the practical stacking of the bistable element 1 from the plurality of layers, since now the ends of each rod can be mechanically connected to one another in a simple manner, without the oscillation capability of each individual rod being impaired.

In contrast, a corresponding fixation of the end portions 100a to each other in the storage according to the prior art is not possible because - as the enlarged view of the end portion in FIG. 4a can be taken - in a deformation of the bistable element 1 and a relative displacement of the end portions 100a to each other takes place. This situation would require special measures for supporting the individual layers 100 in the storage according to the prior art, which in the inventive holder according to FIG. 3 are not required.

The constructive possibilities for the design of the bistable element 1 and for initiating the deformation in the storage according to the prior art are thus very diverse and offer significant advantages over the previously proposed embodiment. A first advantage consists in the fact that a connected bistable element 1 with the same cross-section over its entire length gives better possibilities for passing through a closed guide eye in the board strand. Furthermore, the bending force can be introduced into each individual spring of the stack by a simple and parallel moving pressure piece, whereas in the arrangement according to FIG. 4 a much higher effort would be required. A mass production of a bistable element of a plurality of parallel stratified springs, which are welded together at least at one end, is also possible in the inventive storage of the element without much effort. Furthermore, the edge fiber stress in a thinner material in the same bending stress much lower than a thicker material. The ratio of permissible and actual material load is thus cheaper by the multi-layer design, which has a positive effect on the life of the bistable element. Finally, due to the multi-layered design, the danger of buckling perpendicular to the actual direction of oscillation also decreases disproportionately, since the ratio between width and thickness becomes more extreme when using a cantilever made of many individual layers with the same width and lower thickness.

Finally, a final advantage of the multi-layered design is that the physical and fastening properties of the bistable element 1 as a whole can be influenced in a simple manner by selecting the material for the individual layers 100 differently. It could therefore be provided that in the center of the stack, a single layer of a different material than the surrounding layers is formed, thereby to influence certain properties of the bistable element in a desired manner.

The inventive design and storage of the bistable element 1 is thus ensured that this can be easily and reliably deformed over a longer period of operation in the desired position state. In this way, a reliable control of the warp threads 3 of the loom is achieved.

It must be ensured, however, that at the beginning of the weaving process, the board 2 is in the correct position, for which an initial device is provided, which in the embodiment according to FIG. 1 is realized by a further hydraulic cylinder 10. This initial device is used in the above-described operation of the jacquard machine as an open-jacquard machine only to safely reach the raised or lowered state at startup and could then be omitted if it is ensured by a suitable pre-deformation of the bistable element 1, that this principle at startup basically assumes one of the two stable states. Possibilities for this are also for example from the DE 43 35 620 A1 known. If, on the other hand, the jacquard machine is used as a closed jacquard machine, it is known that after each weft insertion, the bistable elements 1 first assume a neutral position, that is to say a stretched state. If the bistable element 1 is then intended to be deformed specifically into one of the two positional states, the use of the initial device 10 is essential in order to achieve the deflection of the bistable element 1 in the desired direction. Alternative to the embodiment according to FIG. 1 in which the deflection is achieved by means of a hydraulic cylinder 10 whose front end portion 10a is coupled to the bistable element 1, it would also be possible to achieve the initial deformation by means of electromagnetic fields. Thus, in the embodiment according to FIG. 2 provided that two electromagnets 11 and 12 are used, which generate an appropriate electromagnetic field actuation, which achieves the desired initial deflection of the bistable element 1. For this purpose, it may be provided that the bistable element 1 has magnetostrictive or electrostrictive properties at least in a partial region and is deflected in a corresponding manner by the field generated with the aid of the electromagnets 11, 12. To monitor the suitable deflection, two sensors 13 and 14 can also be provided, which detect the positional state of the bistable element 1 in a suitable manner. By this measure, which also in the example according to FIG. 1 can be provided, it is possible to detect malpositions of the bistable element 1 and - if necessary - to correct in a suitable manner.

Overall, therefore, by the present invention, a further improvement of the DE 43 35 620 A1 achieved known concept. Due to the special storage and design of the bistable element reliable and secure control of the boards and the associated warp threads is ensured, with a flawless operation is also possible over a longer period of use.

Claims (9)

1. Jacquard machine for use in a weaving machine, with plates (2) for the lifting and lowering of warp threads (3) of the weaving machine, a plate driving means for causing a lifting or lowering movement of the plates (2), and a plate selection means, which selects specific ones of the plates (2) in order to keep warp threads (3) that are connected with the respective plates (2) in a lifted or in a lowered state, wherein the plate driving means comprises, for each plate (2), a bi-stable element (1) that is connected therewith, which, through an outer deformation stress that acts upon the element (1) in axial respectively in longitudinal direction, alternately assumes a first stable position state, which corresponds to a lifted state of the plate (2), or a second stable position state, which corresponds to a lowered state of the plate (2),
   characterized in that the bi-stable element (1) is formed by a multi-layer elastic deformable rod respectively of a multi-layer elastic deformable plate spring with several rods or springs (100) arranged on top of each other,
   wherein the respective layers (100) of the rod or of the spring are connected at their end regions, and wherein the bi-stable element (1) is firmly clamped on both sides with its end regions (1a, 1b) in a retainer (5a, 5b), wherein the deformation of the element (1) is achieved by bringing together both end regions (1a, 1b) .
2. Jacquard machine according to claim 1,
   characterized in that,
   that each and all layers (100) of the rod or of the spring consist of the same material.
3. Jacquard machine according to claim 1,
   characterized in that
   at least a middle layer of the rod or of the spring consists of a different material than the other layers.
4. Jacquard machine according to one of the claims 1 to 3, characterized in that
   the bi-stable element (1) assumes one of the two stable position states upon impact of the mechanical deformation stress and it assumes a neutral position state without an impact of the mechanical deformation stress,
   wherein an initialization means (10, 11, 12) is provided which, depending on a control signal causes a directed initial deflection of the bi-stable element (1) from its neutral state, such that the bi-stable element (1) assumes one pre-determined position state of the two stable position states after impact of a mechanical deformation stress.
5. Jacquard machine according to claim 4,
   characterized in that,
   the initialization means is formed by a one electromagnet or by a pair of electromagnets (11, 12), in order to exert, after application of an electric command signal, a force component on the bi-stable element (1) such that a corresponding initial deflection is caused.
6. Jacquard machine according to claim 5,
   characterized in that,
   the bi-stable element (1) exhibits, at least in a sub-region, magnetostrictive or electrostrictive properties and in that the initial deflection is caused by the impact of a magnetic respectively of an electric field on the corresponding sub-region of the bistable element (1) .
7. Jacquard machine according to claim 4,
   characterized in that
   the initialization means comprises a hydraulic or pneumatic piston (10), which is coupled with the bi-stable element (1) and which, after charging with a working pressure or with a working under-pressure, causes the initial deflection of the bi-stable element (1) .
8. Jacquard machine according to one of the claims 1 to 7,
   characterized in that
   close to the bi-stable element (1) sensor elements (13, 14) are provided for capturing of a position state of the bi-stable element (1).
9. Jacquard machine according to one of the claims 1 to 8,
   characterized in that multiple plate drive means are provided, the multiple plate drive means being arranged in a cascading way, for operation of several plates (2), the several plates (2) being arranged in a staggered way along the direction of the warp threads.

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