Abstract:
A three-position weaving mechanism for a weaving loom which includes a plurality of shed-forming devices having tackle assemblies disposed in side by side relationship and wherein the lower pulleys of adjacent tackle assemblies are joined by a cord which passes over such pulleys and an intermediate idler pulley which is secured to the frame of the weaving loom.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a device for guiding the warp yarns in three different positions via a plurality of vertically mobile griffe frames. 
     DESCRIPTION OF THE RELATED ART 
     Devices of this type are known to exist, which generally comprise one single griffe frame, as described in French Patent No. 1 513 410 of Dec. 9, 1966. 
     It is desired that two hooks, selectively controlled by two needles, cooperate with the same griffe frame. At each of the ends of the two hooks are fixed the ends of a cord which passes around a pulley, which is connected via a small rod to another pulley, thus forming a tackle assembly. Around this second pulley another cord, of which one of the ends is secured to the frame and the other end includes a collar associated with a heddle. In this device, the two hooks are selectively controlled by two needles, and the two knives with which they cooperate form part of the same griffe frame, thus allowing the collar provided with the warp yarn to arrive either in an upper position, in an intermediate position or in a lower position. The upper and lower positions are respectively reached when the two hooks are retained by the griffe frame and their vertical stroke is equal to that of the frame. The intermediate position is established when one of the two hooks is in mesh with the griffe frame, thereby making it possible to displace the collar by half the vertical stroke of the other positions. 
     Similarly, Swiss Patent No. 367 452 of Apr. 19, 1958 describes a double-lift weaving mechanism in the form of two hooks joined by a cord which passes, as in the French Patent, around one pulley of a tackle assembly, of which the other pulley cooperates with a cord having a fixed end. 
     To produce a three-position weaving mechanism, two systems with two hooks must be used, of which the second pulleys of the tackle assemblies are surrounded by a cord with fixed ends and which encircles the first pulley of a third tackle assembly of which the other pulley is encircled by a harness cord with a fixed end. 
     The three-position weaving mechanisms described in the prior art Patents present certain drawbacks as far as the vertical guiding of the different tackle assemblies is concerned. These assemblies tend to move horizontally during different strokes, and appropriate guiding elements must therefore be provided the cost of such guide element is high and the elements considerably complicate the structure of the mechanism. 
     It is a particular object of the present invention to overcome the drawbacks set forth hereinbefore. 
     SUMMARY OF THE INVENTION 
     The three-position weaving mechanism according to the invention is characterized in that it includes: 
     two adjacent shed-forming devices each including two hooks vertically movable under the effect of knives which move in opposition, in a reciprocating movement. These hooks are joined by a cord passing around one of the pulleys of a tackle assembly; 
     a pulley mounted idly on a shaft which is fixed in relationship with respect to the frame of the mechanism; 
     and a cord of which one of the ends is anchored to the frame of the mechanism and which successively passes over the second pulley of the tackle assembly of the first shed-forming device, the idle pulley, and the second shed-forming pulley of the tackle assembly of the second device. The second end of the cord is connected with a collar to which at least one heddle is fastened. 
    
    
     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: 
     FIGS. 1 to 3 are side elevational views illustrating the assembly of the elements of a weaving mechanism according to the invention, with the collar of the harness being respectively in lower, intermediate and upper position. 
     FIG. 4 is a view similar to that of FIG. 1, but illustrating a preferred embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, FIG. 1 shows two shed-forming devices A and B each comprising two movable hooks 1 and 2 adapted to cooperate with two griffe frames 3 and 4 having knives 3a and 4a. 
     Hooks 1 and 2 include a rectilinear principal arm 1a and 2a of which the upper end is provided with a barb 1b and 2b, while their lower ends are bent to form a second, vertical, arm 1c, 2c, provided with a hooks, 1d, 2d cooperating respectively with bars 5a and 5b of the comberboard grid 5. 
     Each of the arms 1a, 2a of hooks 1 and 2 passes in the ring of a press needle referenced 6a, 6b and 7a, 7b which, in known manner, makes it possible for the barbs 1b, 2b to be displaced from the knives 3a, 4a when it is not desired that the hooks be gripped by the knives. 
     Links 1e, 2e of arms 1a-2c or 1a-2c respectively of hooks 1 and 2 are joined by a cord 8 passing around a pulley 9a of a tackle assembly 9. 
     Between the two devices A and B, a pulley 10 has been provided, rotating freely about a spindle 11 secured to the frame 12 of the weaving mechanism. The second pulleys 9b of the two tackle assemblies 9 of the two devices A and B, and pulley 10 are engaged by another cord 13 of which one of the ends 13a is attached to a fixed point 12a of the frame 12, while its other end 13b carries a snap 14 which constitutes the collar to which at least one heddle 15 is fixed. 
     A double tackle assembly is thus produced, enabling the three desired positions of the collar 14 to be obtained, namely a low position corresponding to the lower position of the warp yarns (FIG. 1), a horizontal or intermediate position thereof (FIG. 2) and a high or upper position of these yarns (FIG. 3). 
     When the warp yarns are to be in low position (FIG. 1), the arms 1a of devices A and B are pressed so that knife 4a does not engage the corresponding barbs 1b when the griffe frame 4 rises. Similarly, the hooks 2 are pressed so that barbs 2b are engaged by the knife 3a corresponding to the griffe frame 3 when it rises. In this way, the collar 14 remains in the low position and all the hooks 1d, 2d of devices A and B rest on the bars 5a, 5b of the grid 5. 
     The intermediate position shown in FIG. 2 is produced by the fact that the arms 1a, 2a of the hooks 1 and 2 of device A are pressed alternately, so that the hooks 1d, 2d are in abutment against the bars 5a, 5b of the grid 5. On the contrary, barbs 1b, 2b of the hooks of device B remain in mesh with the knives 3a, 4a during the reciprocating movement of the griffe frames 3 and 4. 
     Finally, if collar 14 is in the high position (FIG. 3), the barbs 1b, 2b of the four hooks 1 and 2 of devices A and B are left in mesh with the knives 3a, 4a of the two griffe frames 3 and 4. 
     Of course, the preceding arrangement may also be applied to a weaving mechanism of the type described in Applicants&#39; U.S. Pat. No. 4,739,806. 
     FIG. 4 shows a module 16 comprising a plurality of vertical partitions 16a, 16b, etc . . . , between each of which are located the shed-forming devices A, B, C, D . . . , each constituted by two hooks 17, 18 joined by a cord 19 passing over the first pulley 20a of a tackle assembly 20 guided between the partitions. 
     These hooks 17, 18 move vertically via knives disposed on griffe frames (not shown) and exhibit a reciprocating movement. Retaining elements associated with electro-magnets are capable of retaining the mobile hooks 17, 18 in high position. Such a structure according to U.S. Pat. No. 4,739,806 will not be described in greater detail, however the teachings of the patent are incorporated herein by reference. 
     In accordance with the invention, an idle pulley 21 has been provided, of which the shaft for rotation 21a is secured on a horizontal wall or element 16c of the module 16. The second pulleys 20b of the tackle assemblies 20 of two devices A and B of the module 16 and the idle pulley 21 are engaged by a cord 22 of which one of the ends 22a is anchored to a fixed point 16d of the module. While its other end 22b carries a snap 23 which constitutes the collar to which at least one heddle 24 is fixed. 
     A double tackle assembly is thus obtained, making it possible to produce the three positions described hereinabove, but applied to a module described in Applicants&#39; aforementioned U.S. patent and which requires no additional guiding means with respect to those of a standard module, with the result that a mechanism thus produced is economical and highly simple to manufacture and maintain. 
     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.