Abstract:
This invention relates to a device for forming the shed in a weaving loom, wherein the elements which constitute the system for lifting the warp yarns are, from top to bottom, an electro-magnet, two blades, two mobile hooks and a lifting beam. These elements are disposed one below the other between two vertical separating partitions constituting an assembly. A certain number of assemblies are assembled in a row so as to form a module which may be selectively inserted within the loom frame.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device for forming the shed of a weaving loom. 
     2. History of the Art 
     It is known that, in order to open the shed of the layer of warp yarns of a weaving loom, a mechanism is used which is adapted to lift a certain number of these yarns while leaving the others at their lower level so as to allow the passage of a pick. 
     Shed forming devices are generally composed of hooks coupled to a heddle and which are lifted and lowered by griffe boxes, a selection being made from a card to determine whether or not the hooks are gripped by the griffe boxes. 
     Systems also exist wherein each harness cord is associated with the first pulley of a lifting beam which comprises a second pulley surrounded by a funicular member of which the ends are fast secured with two hooks which are continually displaced vertically in reciprocal manner in opposite directions by means of appropriate devices such as knives. When it is desired to lift a harness cord, one of the mobile hooks is gripped when, at its top dead centre, by a retaining hook generally actuated by an electro-magnet. Such a device is described in German Patent Application No. 2 204 815 withdrawn since June 1974. The different elements of the shed forming devices of the type described in that Patent Application are free in space, this leading to a large number of drawbacks. The mobile hooks associated with the ends of the funicular element are firstly in the isolated state, with the result that, if a harness cord breaks, it is very difficult to replace, all the more so as it is remote from the edge of the device in question. 
     It is also observed that the lifting beam, i.e. the system with two pulleys of which one is partially surrounded by the funicular element ensuring connection between the two mobile hooks, while the other cooperates with the harness cord, is subjected to parasitic movements. A pendulum movement is very often observed of the lifting beam, as well as its tendency to rotate. These different drawbacks have led to a limitation of the number of harness cords used on the known high-speed machines. 
     There again, a break of the funicular element brings about a drop of the lifting beam and its harness cord. 
     OBJECT OF THE INVENTION 
     The object of the improvements forming the subject matter of the present invention is to overcome the drawbacks set forth hereinabove and to produce a shed forming device in a weaving loom which can include a large number of systems for lifting the warp yarns. 
     To this end, the device according to the invention is essentially characterized in that the elements of each system, i.e. the retaining hooks with their selection device, the mobile hooks and the lifting beam, are disposed between two vertical partitions connected to each other so as to form a compact, independent assembly. 
     According to a particularly advantageous embodiment, a certain number of assemblies are assembled side by side so as to constitute a module which may easily be removed or returned into position in the event of mishap in place of any other, since it is pre-adjusted so as to be readily replaceable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic view illustrating a shed forming device in a weaving loom in the form of a module made according to the invention and intended to control two heddles only. 
     FIGS. 2 to 5 illustrate the conventional operation of a shed forming device of which each harness cord is associated with a funicular element provided with two hooks moving vertically in reciprocal movement. 
     FIG. 6 is a transverse section showing the arrangement of the elements of each system for controlling the harness cords between two separating partitions. 
     FIG. 7 shows in perspective a module made in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, FIG. 1 schematically illustrates a layer of warp yarns 1 disposed in a weaving loom and which comes from a beam 2. Each warp yarn passes in the mail 3a of a heddle 3 adapted to open the shed to allow the passage of a pick with a view to forming a fabric which is wound on a reel 4. In the example shown, it is assumed that there are only two heddles 3, or only two groups of heddles, some being in high position and the others in low position. Reference 3&#39; designates the heddle in low position and reference 3 the one in high position. The lower ends of each heddle are connected to the frame by traction springs 5, while their upper ends are each secured with harness cords 6. The harness cords are lifted and lowered by means of a shed forming device referenced 7. 
     The shed forming device 7, in the case of the present invention, includes a funicular member 8 (see FIGS. 2-7) with each of the ends of which a hook 9 is associated. These hooks include a lateral nose element cooperating with a knife 10 which is vertically and reciprocally moved in a manner which is well known. The funicular element 8 passes partially around the first pulley 11 of a lifting beam 12 of which the second pulley 13 supports a harness cord 6. The end of the harness cord opposite that which is connected to the heddle 3 is anchored to a fixed point 14 relative to the frame of the machine. The upper part of device 7 is provided with retaining hooks made in the form of flexible blades 15 associated in manner known per se with a single electro-magnet 16. The electro-magnet is adapted to vary the position of the blades so that the blades are displaced towards the centre of the device when the electro-magnet is energized in order that the curved ends 15a thereof may grip one or the other of, or both hooks 9. 
     In FIG. 2, the electro-magnet 16 is not energized, with the result that hooks 9 are lifted and lowered without being gripped by the curved blades 15 so that the corresponding warp yarn remains in its low position. FIG. 3 illustrates the reverse position of the mobile hooks which changes nothing in the positioning of the heddle and corresponding warp yarn since the lifting beam remains in stable position. 
     If, in the position of the mobile hook of FIG. 3, the electro-magnet 16 is energized, the two blades are attracted so that, when the corresponding knife descends, the hook in question remains in high position, so that blade 10 redescends without the corresponding hook. When the other blade rises, the lifting beam 12, as well as the harness cord and heddle in question will rise, arriving in the position of FIG. 4 in which the two mobile hooks remain in high position with the result that the corresponding warp yarn remains lifted in open shed position. 
     In order to lower the warp yarn from its high position, the energy to the electro-magnet is cut off, with the result that the two blades move away from its core. One of the hooks is gripped by the first knife which arrives at its level and provokes its descent while the other remains hooked to the curved blade 15. When the other knife arrives at the level of the hook which remained in a high position, it unhooks it from the curved end 15a of the blade 15 so that the position illustrated in FIG. 2 is resumed, wherein the nose element of the hook engages with knife 10. 
     It is unnecessary to describe the operation of such a shed forming device further, as it is well known in the art. 
     To facilitate understanding, the assembly of the elements controlling a harness cord, i.e. the electro-magnet 16, the two curved elastic blades 15, the two mobile hooks 9 with their funicular element 8 as well as the lifting beam 12, will be referred to in the present specification as a &#34;system&#34;. 
     According to the invention, each system described hereinabove is placed between two separating partitions 17 (see FIGS. 6 and 7), connected together at the level of their head 17a and their lower part 17b. Moreover, spacers 17c ensure the spaced apart relationship of two adjacent separating partitions, allowing passage of the mobile hooks 9. A compact and independent assembly is thus formed. 
     It will be noted that each separating partition 17 is provided with an oblong opening 17d constituting a guide for the lifting beam 12 which comprises two side elements 12a each engaging in an opening 17d. 
     The head 17a of each separating partition 17 is provided with two shoulders 17e adapted to rest on two crosspieces 18 of the device 7. 
     It is observed that the lower part 17b of the separating partitions 17 comprises a notch 17f enabling it to overlap a third retaining crosspiece 19 or vice versa. 
     As illustrated in FIG. 7, a certain number of independent assemblies such as the one illustrated in FIG. 6 are assembled together so as to form a module 20 comprising for example six to ten assemblies, this figure not being limiting. The module supports a board 21 incorporating the circuit for energizing the corresponding electro-magnets. The board is plugged into complementary plugs borne by devices 7 and which have not been shown in the drawings. 
     By the manner in which it is designed, each module 20 may be removed for maintenance or repair purposes in simple manner and in a very short time. It is obvious that a module is returned into position under the same conditions by the cooperation of its retaining means 17e, 17f with crosspieces 18, 19. 
     It is observed that, in FIGS. 6 and 7, that end of the harness cord 6 opposite the one associated with the heddle is engaged in a notch 17g made in the base of each separating partition in order to be wedged therein, for example by means of an endpiece overmoulded on the corresponding end of the heddle. 
     It must, moreover, be understood that the foregoing description has been given only by way of example and that it in no way limits the domain of the invention which would not be exceeded by replacing the details of execution described by any other equivalents. It goes without saying that the modules may be disposed in any orientation, the knives having a corresponding direction of displacement.