Abstract:
Heddle frames in which each upright includes an opening and a pair of spaced bearing surfaces and wherein each horizontal crosspiece includes a fixed and a movable jaw which extend outwardly therefrom and which jaws are engageable with the bearing surfaces upon adjustment of the movable jaws to thereby secure the horizontal crosspieces to the uprights.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to heddle frames which are mounted on weaving looms and which are connected to a dobby or other mechanism for forming the shed, in order to produce a fabric in accordance with the desired weave. 
     2. History of the Related Art 
     As is known, heddle frames are constituted by the assembly of four separate elements, namely two superposed horizontal crosspieces and two lateral uprights. The edge of the crosspieces faces the inside and are fitted with a rail for fixing the hooks provided at the ends of the yarn-guide heddles. In order to facilitate positioning of these heddles, the upright-crosspiece assembly arranged in each of the corners of the frame is in easily dismountable form. The present invention is precisely based on the observation that the choice of the mode of assembly is more delicate than it might appear at first sight. 
     Certain constructions have adopted a system of assembly allowing a perfect rigidity of the frame to be obtained, but such a system often employs a relatively high number of separate pieces and fixing members, thus rendering the dismounting and reassembly manoeuvres fastidious. On the contrary, other solutions proposed have rendered operation easy, but this advantage is generally acquired to the detriment of solidity. 
     European Pat. No. 0189216 describes a system of dismountable assembly in which each upright comprises a nose element projecting laterally on the wall of the upright facing the inside of the frame and of which the horizontal edges form bearing surfaces adapted to cooperate with a fixed piece and a spring leaf. These two pieces are connected to each other by a locking screw in order to act as jaws for immobilizing the above-mentioned nose element. 
     It will be noted that, although such an arrangement ensures simplicity of manoeuvre due to the uniqueness of the screw for closing the jaws, it has the drawback of applying to the uprights of the frame bending moments due to the lateral offset of the projecting nose element with respect to the vertical axis of the uprights. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome these aforementioned drawbacks by providing a heddle frame for weaving looms, of the type constituted by the dismountable assembly of four elements comprising two superposed horizontal crosspieces and two lateral uprights, wherein at least one of the ends of each crosspiece is provided with a mobile jaw connected by a locking screw to a fixed jaw. With this construction, by manoeuvring the screw, the two jaws are applied against combined bearing surfaces provided on the adjacent end of the upright being assembled. The bearing surfaces are defined by at least one opening made in the wall of the upright which faces the jaws, so that the bearing surfaces lie in the axis of the upright in order to avoid any bending moment at the level thereof. 
    
    
     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 view in perspective, with parts broken away, illustrating the arrangement of the pieces employed for assembly, located in one of the two upper corners of a heddle frame according to the invention. 
     FIG. 2 is the corresponding side view, likewise with parts broken away. 
     FIG. 3 reproduces FIG. 2 after assembly of the upright and of the crosspiece shown. 
     FIG. 4 illustrates a variant embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, reference 1 designates one of the two ends of the upper horizontal crosspiece of the frame in question. The crosspiece is formed, in manner known per se, by a hollow section reinforced by inner horizontal partitions. In the end 1a of this crosspiece is engaged a fixed jaw 2 provided with a horizontal heel 2a which is in position by means of the two screws 3 which secure a conventional lug 4 (as shown in FIG. 2) which lug is intended for anchoring the drawing member associated with the dobby. 
     Opposite the heel 2a, the jaw 2 includes a projecting nose element 2b adapted to form a clamping jaw, as will be more readily understood hereinbelow. Opposite this nose element or fixed jaw 2b lies a nose element or mobile jaw 5a provided at the end of an appropriately sectioned rocking jaw 5 connected to the fixed jaw 2 by a screw 6, as illustrated in FIGS. 2 and 3. It should be observed that jaws 2b and 5a define therebetween an opening 2c of substantially trapezoidal cross section, of which the small base faces the outside of the end 1 of the crosspiece in question. 
     This opening 2c is adapted to receive an assembly member 7a having the same trapezoidal section, which member is secured with the upper end of the corresponding upright 7 of the heddle frame. To that end, this upright 7, having a U-shaped cross section, has an opening 7b cut out at the level of its central web, which opening thus defines the member 7a mentioned above. Member 7a includes two opposite bearing surfaces 7c oriented obliquely to cooperate with the jaws 2b and 5a. 
     Under these conditions, it will be understood that, when the mobile jaw 5 has been brought, after screw 6 has been unscrewed, to the low position illustrated in FIGS. 1 and 2, in which it rests against a partition 1a of the crosspiece 1, the member 7a is capable of being introduced inside the opening 2c by inserting the top of the upright 7 therein. It then suffices to screw the screw 6 in order to effect displacement of the mobile jaw 5 upwardly. The jaw 5a will to some extent close the open lower part of the trapezoidal opening 2c of the fixed jaw 2. 
     As illustrated in FIG. 3, after the screw 6 has been manipulated to close jaw 5a, the member 7a is captive inside the opening 2c. The connection thus ensures a perfect rigidity due to the substantially trapezoidal section of the joint. It will be observed that mutual assembly is effected in the axis of the upright 7, without any overhang and without creation of bending moment. 
     Of course, this mode of assembly is advantageously adopted in the four corners of the heddle frame which, despite its resistance to deformation, is capable of being easily disassembled in order to replace the conventional yarn-guide heddles engaged on a horizontal rail 8 provided immediately below or above the inner horizontal edge of each crosspiece 1. The operations of assembly and of disassembly are simplified since they require only the manoeuvre of one screw 6 in each of the corners of the heddle frame, it being observed that this screw may be easily rendered captive. 
     It goes without saying that the uprights 7 may present any desired cross-section, the U-shaped construction shown hereinabove having been indicated only by way of example. 
     In the embodiment illustrated in FIG. 4, the fixed jaw, here referenced 12, comprises an upwardly facing nose element or jaw 12b, whilst the nose element or jaw 15a of the mobile jaw 15 faces downwardly. The two jaws 12 and 15 are connected to each other by a spring 19 which tends to apply the mobile jaw 15 against the inner partition 1a of the crosspiece. It will be readily understood that the nose elements or jaws 12b and 15a are adapted to be introduced into an opening 17b of the adjacent upright 17. The subsequent screwing of the screw 16 ensures spaced apart relationship of the two jaws which thus abut against the bearing surfaces 17a formed by the two opposite edges of the opening 17b, consequently ensuring the rigid assembly of the two elements 1 and 17 of the heddle frame.