Abstract:
This invention relates to a shake-proof assembly for parts of spectacles and like applications, wherein there is engaged on the screw a bush provided with oblique jaws which, when the screw is placed in position, are pushed radially against the shank thereof by an inner shoulder formed with the bore of the parts of the spectacles.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the spectaclemaking industry and concerns more especially the mutual assembly of certain of the elements constituting the frames, such as in particular the eyewire clamps intended for retaining the lenses within the bezels of the face of metal glasses. 
     2. History of the Related Art 
     Such assembly is generally obtained with the aid of screws which allow dismantling, for example for replacing one of the lenses in the above-mentioned case of eyewire clamps. Practice has shown that these screws, of which the thread most often is steeply pitched, unscrew very easily, with the result that, in order to avoid any risk of untimely disconnection, angular blocking of each screw must be provided. 
     In practice, a certain number of angular blocking elements tending to render the screw shake-proof have been proposed. In particular, hammering or superficial gluing notched surfaces beneath the head, of the screws or the positioning of a longitudinal retaining pallet made of plastics material, similar to a key, have been proposed. However, these known techniques are not entirely satisfactory, for, if they are conducted so as to prove really efficient, they oppose the voluntary removal of the assembly screw, for example upon replacement of a lens in the case of an eyewire clamp, or are no longer efficient after several successive assemblies. 
     SUMMARY OF THE INVENTION 
     It is a principal object of the present invention to overcome the drawback of prior art fasteners for eye wear and the invention relates to this end to a shake-proof system of assembly which consists essentially in mounting axially on the screw a bush of which the outer conical wall is slit longitudinally so as to be deformable, while, inside the smooth part of the bore which is to receive the screw, there is provided an annular shoulder adapted to abut, upon screwing, against the conical wall of the bush in order to urge it by deformation against the shank of the screw which is thus immobilized or secured angularly. 
    
    
     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 an axial section assembly view showing the different elements of a shake-proof assembly according to the invention. 
     FIG. 2 is a view in perspective of the bush, of the present invention. 
     FIG. 3 reproduces FIG. 1 after assembly of the elements and tightening of the assembly screw. 
     FIGS. 4 and 5 are views corresponding to FIG. 2 and FIG. 3, respectively, but illustrating a variant embodiment of the invention. 
     FIG. 6 illustrates another variant embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, it has been assumed that the invention is applied to the assembly of one of the two eyewire clamps of a metal spectacle frame. The representation has, of course, been made to a large scale so as more readily to illustrate the invention. 
     References 1 and 2 designate the two ends of the eyewire of the face of the frame, which eyewire is hollowed out with the bezel adapted to receive the edge of a lens such as 3. The eyewire clamp associated with eyewire 1,2 comprises two transverse blocks 4, 5, respectively, which must be brought together and assembled to ensure retention of the lens 3. 
     The system of assembly according to the invention comprises a screw 6 associated with a bush 7. In the embodiment envisaged in FIGS. 1 to 3, and as clearly shown in FIG. 2, the bush 7 comprises a continuous ring 7a, longitudinally secured with a series of jaws 7b oriented obliquely, thus giving the bush a truncated profile whose large base corresponds to the ring 7a. 
     Screw 6 is intended to pass freely through a bore 5a made in the block 5, before being screwed in a corresponding tapping 4a made in the block 4. According to the invention, an annular shoulder 5b, determined by two parts of different diameters, has been provided inside the bore 5a. 
     Bush 7 is engaged on the screw 6, being turned so that its ring 7a is disposed against the projecting head 6a of the screw. Under these conditions, it will be readily appreciated that, when this screw 6 is rotated in order to screw in the tapping 4a (cf. FIG. 3), the jaws 7b, which are capable of deforming elastically due to their mutual independence, abut against the shoulder 5b which pushes them radially inwardly, thus causing the jaws to abut against the smooth part of the shank of the screw 6. It will be observed that the longitudinal edges 7c of the jaws 7b constitute edges which, by anchoring against the shoulder 5b, ensure angular immobilization of the bush 7, with the result that the screw 6 is thus tightly retained and cannot unscrew in untimely manner, while remaining capable of being dismantled for the purpose of replacing the lens 3. 
     Tests have shown that the shake-proof assembly according to the invention proved perfectly efficient. It will be observed that this efficiency is further reinforced due to the relatively malleable nature of the nickel silver which most often constitutes the eyewires of metal frames and which is hammered at the level of shoulder 5b. 
     In order to render the bush 7 captive prior to assembly thereof on the spectacle frame, the shank of the screw 6 may advantageously be provided with a groove 6b adapted to form stop for the ends 7d of the deformable jaws 7b, bent inwardly in the manner of grasping hooks. This bush 7 is thus retained on the screw 6, in the manner illustrated at 7&#39; in FIG. 1. 
     It will be understood that the number of jaws 7b of the bush may vary to a wide extent. FIGS. 4 and 5 illustrate a variant in which the bush, referenced 17, is cut out with a single longitudinal slot which, after removal of matter, defines two edges 17c. Operation is identical, in that the bush 17 deforms radially under the action of the shoulder 5b and is applied against screw 6. 
     In the case of FIGS. 1 to 3 as well as in that of FIGS. 4 and 5, it should be observed that withdrawal of the bush 7 or 17 upon manual unscrewing is ensured by abutment of the edge of groove 6b against the ends 7d, 17d. However, care should be taken that withdrawal of the bush and disappearance of the angular retention effect occur only against a noteworthy angular movement (one turn, for example), so as to allow adjustment of the screwing without causing release of the screw 6. Tests have shown, on this subject, that retention is maintained even if the head 6a of the screw 6 is no longer in abutment against the bush 7, 17. 
     When it is desired to render the system virtually disassemblable, the embodiment illustrated in FIG. 6 may be employed, in which the bush, referenced 27, presents an inner bearing surface 27e with conical profile adapted to apply against a corresponding bearing surface 26c likewise with conical profile made on the screw 26, level with the head 26a thereof, while the bore 25a of the block 25 comprises a part 25b with a conical profile opposite that of the bearing surface 26c. The part 25b performs the same role as the shoulder 5b to compress the bush 27 radially when the screw 26 is tightened, but the inversion of the conical sections has for its result that the unscrewing of the screw 26 still ensures radial compression of the bush and therefore increases the mechanical retention of the screw. 
     Furthermore, it will be readily appreciated that, although the invention is more especially concerned with the domain of spectacles, it may also find advantageous applications in other technical sectors where equivalent problems of angular retention arise.