Screw device for clamping components of spectacles and method of manufacturing same Technical field

The present invention concerns a screw device for clamping components of spectacles, having the characteristics mentioned in the preamble of main claim 1. The invention also relates to a method of manufacturing the screw device. Technological background

The invention applies particularly to the specific technical field of spectacle manufacture, wherein screw devices of the aforesaid type, including a threaded shank which may or may not be provided with an operating head, are used for clamping a wide variety of components. Cited solely by way of example are the screw clamping of frame members, such as the lugs or the central nasal support bridges, to the corresponding "rimless" type of spectacle lenses, or the clamping of the threaded pins constituting the hinge pins in conventional spectacle frames, or also the clamping of "tube" appendages provided in the parts of lens-holding rims intended to be clamped to one another in order to hold the lens on the frame. In such applications it is required that the screw connection should have characteristics such as to guarantee efficient locking and should prove to be reliable in maintaining the clamping action in order to oppose any unscrewing which might compromise the functioning of the spectacles. Description of the invention

The principal aim of the invention is that of providing a screw device for clamping components of spectacles which is capable of offering an

improved and more reliable clamping action and which at the same time is of simple construction to produce, a further aim therefore being also that of providing a manufacturing method which fulfils that requirement.

These and still other aims which will appear hereinafter are achieved by the invention by means of a screw device and a method of manufacturing same which are provided according to the attached claims. Brief description of the drawings

The characteristics and advantages of the invention will become clearer from the following detailed description of some preferred exemplary embodiments thereof, illustrated by way of non-limiting example with reference to the appended drawings, in which:

Figures 1 and 2 are views respectively in front elevation and in plan from above of a first example of a screw device produced according to the invention, - Figure 2A is a view in partial section of a clamping system between a lens and a spectacle frame member in which the screw device of the preceding figures is used,

Figures 3 and 4 are views respectively in front elevation and in plan from above of a second example of a screw device produced according to the invention,

Figures 5 and 6 are views respectively in front elevation and in plan from above of a third example of a screw device produced according to the invention,

Figures 7 and 8 are views respectively in front elevation and in plan from above of a fourth example of a screw device produced according to the invention,

Figures 9 and 10 are views respectively in front elevation and in plan from above of a fifth example of a screw device produced according to the invention,

Figures 11 and 12 are views respectively in front elevation and in plan from above of a sixth example of a screw device produced according to the invention, Figures 13 and 14 are views respectively in front elevation and in plan from above of a seventh example of a screw device produced according to the invention,

Figures 15, 16 and 17 are views respectively in front and side elevation and in plan from above of an eighth example of a screw device produced according to the invention,

Figures 18, 19 and 20 are views respectively in front and side elevation and in plan from above of a ninth example of a screw device produced according to the invention,

Figures 21, 22 and 23 are views respectively in front and side elevation and in plan from above of a tenth example of a screw device produced according to the invention,

Figures 24 and 25 are views respectively in front elevation and in plan from above of a further exemplary embodiment of the invention,

Figures 26 and 27 are views respectively in front elevation and in plan from above of a further alternative embodiment of the invention illustrated in Figures 24 and 25. Preferred ways of implementing the invention With initial reference to Figures 1 and 2, the reference 1 indicates as a whole a first example of a screw device for clamping components of spectacles, produced according to the invention. The device, also referred to hereinafter simply by the term "screw", is designed to be used in the most varied systems for clamping between spectacle components. A first example of application is the screw locking of frame members (for example the lugs or central nasal support connecting bridges) to lenses or for the clamping of arms of spectacles to the corresponding articulation lugs in which the screw or the threaded pin may also function as a hinge pin. Another example of application is that of clamping of the "tube" appendages provided on the lens-holding rims for clamping same in order to hold the lens on the frame. Yet another example is that of the coupling of the screws with threaded bushes for fixing metal components onto parts made of plastics. It is to be understood that the screw according to the invention may obviously find application in all those screw fixing systems provided in frames for spectacles, in which the clamping of any desired component of the spectacles to another part or component of the frame is required.

Figure 2A illustrates a typical application in which the screw of the invention is used for clamping a spectacle lens 2 to a lug 3 for the articulation of an arm 4, by means of screwing engagement in a locking nut 5, the screw passing through a through hole provided at the front in the

lens. As already specified above, it is to be understood that the clamping system shown in Figure 2A represents one of the possible applications in which the screw according to the invention may be used, it being possible in principle for the screw to be used whenever a screw/nut locking between components of spectacles is required.

The screw 1 comprises a shank 7 extending in an axial direction, indicated by X, and which is externally threaded for a predominant section 7a of the shank, with a thread designated by 7b in the drawings. At one of its axial ends, the threaded shank 7 is extended in a screw head 8 having an impression or slot 8a for the engagement of the point of a screwdriver or another implement for the operation of the screw in the screwing/unscrewing phases.

In the shank 7, preferably of cylindrical configuration, a cut interruption 9 is also provided, extending parallel to the main axis X, the interruption defining in the shank respectively a first and a second portion 11, 12, extending behind the interruption 9 and joined to each other by a region 13 of the shank not affected by the cut 9. The cut interruption 9 continues axially along the entire length of the shank 7 and of the head 8 and extends radially in the shank close to, or slightly beyond, the diametral median plane containing the main axis X and directed transversely to the cut 9, as clearly illustrated in Figure 2.

The thread diameter of the shank 7 is also selected to be greater than the corresponding thread diameter of a nut (not shown) in which the screw 1 is intended to engage by screwing. In this way, the resilient deformation induced in the screwing operation, as a result of the difference

in the aforesaid thread diameters between the screw and the nut, and tending to urge the shank portions 11, 12, by resilient return, against the corresponding nut, is such as to increase the clamping action between the threads of the screw and nut in reciprocal engagement, consequently hindering unscrewing thereof. Solely by way of example, it is indicated that with nominal screw diameters of 1.4 mm, the over-sizing of the screw thread diameter may conveniently be selected between 0.02 and 0.05 mm, such values providing an effective increase in the clamping action between the screw and the nut. This clamping action is increased by the effect of the greater stresses present between the engaged threads of the nut and the screw.

Therefore, by means of the over-sizing of the thread diameter of the screw, the aforesaid increased clamping effect is obtained, induced by the resilient return of the portions 11, 12 deformed during the screwing of the screw into the corresponding nut.

The cut interruption 9 is preferably obtained by means of longitudinal cutting of the entire screw 1.

The screw is furthermore conveniently produced from a metallic material with resilient properties, for example from steel or another alloy. Figures 3 and 4 show a second exemplary embodiment of the screw according to the invention, wherein details similar to those of the preceding example are designated by the same reference numbers.

The screw of this example differs from that of the preceding example, substantially in that a head 8 of different configuration is provided, as clearly illustrated in Figure 3.

Figures 5 and 6 show a third exemplary embodiment of the screw according to the invention, wherein details similar to those of the preceding examples are designated by the same reference numbers. In this case also, the screw of this example differs from the preceding ones, mainly in that a head 8 of different configuration is provided, as clearly illustrated in Figure 5.

Figures 7 and 8 show a fourth exemplary embodiment of the screw according to the invention, designated as a whole by Ia, wherein details similar to those of the preceding examples are designated by the same reference numbers. The screw Ia differs mainly from the exemplary embodiment of Figures 1 and 2 in that it is provided with a central through hole 15, coaxial with the main axis X and extending for the entire axial length of the shank and of the screw head. Furthermore, the cut interruption 9 extends radially in the screw until it intersects the hole 15. Preferably, the diameter of the hole 15 is selected to be greater than the distance between the shank portions 11, 12 defining the width of the interruption 9. The provision of the hole 15 makes it possible to obtain an effective resilient return action following the deformation of the threaded shank during the phase of screwing into the corresponding nut. Figures 9 and 10 show a fifth exemplary embodiment of the screw according to the invention, designated as a whole by Ib, wherein details similar to those of the preceding examples are designated by the same reference numbers. This represents a variant of the preceding example, and in which the main difference from the screw Ia lies in the different configuration of the screw head 8.

In this case also, a central through hole 15 is provided, which is intersected by the cut interruption 9.

Figures 11 and 12 show a sixth exemplary embodiment of the screw according to the invention, designated as a whole by Ic, wherein details similar to those of the preceding examples are designated by the same reference numbers. This represents a variant of the preceding example, and in which the main difference from the screw Ia lies in the different configuration of the screw head 8.

In this case also, a central through hole 15 is provided, which is intersected by the cut interruption 9.

Figures 13 and 14 show a seventh exemplary embodiment of the screw according to the invention, designated as a whole by Id, wherein details similar to those of the preceding examples are designated by the same reference numbers. In this example the screw is configured exclusively as a cylindrical threaded shank, without the provision of any screw head, as clearly illustrated in the corresponding drawings.

Figures 15 to 17 show an eighth exemplary embodiment of the screw according to the invention, designated as a whole by Ie, wherein details similar to those of the preceding examples are designated by the same reference numbers.

This example of screw differs in particular from that of Figures 1 and

2, in that it further comprises, in the connecting region between the screw head and shank, a slot 16 which extends in the shank transversely to the axial direction X. The slot, more particularly, extends perpendicularly to the axial direction X and extends radially in the portion of shank affected by the

cut interruption 9, such that the slot 16 and the interruption 9 intersect one another, as clearly shown in Figure 15.

The slot 16 and the cut interruption 9 further extend radially in the shank to substantially the same depth, to behind the diametral median plane directed perpendicularly to the interruption.

The provision of the slot advantageously allows the possibility of resilient deformation of the shank portions 11 and 12 to be increased compared with that of the head portions 8 defined by the slot 9, consequently increasing the resilient return action and the consequent locking between the engaged threads of the screw and the nut.

Figures 18 to 20 show a further exemplary embodiment of the screw according to the invention, wherein details similar to those of the preceding example are designated by the same reference numbers. The screw of this example differs from the preceding one, mainly in that a head 8 of different configuration is provided, as clearly illustrated in the corresponding drawings.

Figures 21 to 23 show a further exemplary embodiment of the screw according to the invention, wherein details similar to those of the preceding example are designated by the same reference numbers. In this case also, the screw of this example differs from the preceding one, mainly in that a head 8 of different configuration is provided, as clearly illustrated in the corresponding drawings.

With regard to the method of manufacture of the screw according to the invention, provision may be made for the shank 7 to be produced starting from a solid cylindrical semi-manufactured product, with

subsequent external threading and longitudinal cutting, in order to obtain the interruption 9. When the central through hole 15 is provided, this latter may conveniently be obtained by means of through drilling of the shank and of the screw head, if provided. As an alternative, provision may be made to produce the shank 7 starting from a tubular semi-manufactured product, subjected to external threading, of preselected diameter, and subsequently cut longitudinally to produce the cut interruption 9. In this case, starting from a tubular profile, the through hole 15 is defined by the central cavity of the tubular member, not therefore requiring any drilling operation.

Figures 24 and 25 show a further exemplary embodiment of the screw according to the invention, wherein details similar to those of the preceding examples are designated by the same reference numbers. The screw of this example differs from the preceding ones, mainly in that the threaded section of the shank 7 comprises two parts, indicated by Tl, T2, extending in axial prolongation of each other, having respective different thread diameters Dl, D2. More particularly, the thread diameter of the part Tl, extending behind the head 8 is selected to be less than the diameter of the other part T2. The thread diameter of one or both the parts Tl, T2 is further selected to be greater than the corresponding diameter of a nut in which the corresponding part is intended to engage by screwing, so as to obtain the advantages of increased clamping already highlighted in the preceding examples. The screw of this example lends itself particularly to applications in which the threaded sections Tl, T2 each engage a corresponding hole of a respective item. Since the section Tl of lesser

diameter of the shank is less resistant (and therefore more flexible) than the section T2 of larger diameter, this characteristic may for example be exploited whenever differentiation of the resilience along the shank is necessary. Figures 26 and 27 show an alternative embodiment of the preceding example, wherein details similar to those of the preceding examples are designated by the same reference numbers. The screw of this example differs from the preceding one, in that the thread diameter of the part Tl, extending behind the head 8, is selected to be greater than the diameter of the other part T2. Similarly, the screw of this example also lends itself particularly to applications in which the threaded sections Tl, T2 each engage a corresponding hole of a respective item. In this case the section T2 of lesser diameter, extending at the free end of the screw, may permit easier centring of the screw in the phase of insertion and locking of the components, a problematic task which is encountered for example during the insertion of the screws into the lens-clamping tubes of the frames.

The invention thus achieves the proposed aims, obtaining numerous advantages with respect to the known solutions.

The principal advantage lies in the fact that the screw device according to the invention, which may or may not be provided with a head or configured as a simple threaded pin or shank, makes it possible to obtain an increased clamping capacity in the screw/nut coupling of the system for locking the frame components, consequently hindering unscrewing. Such a screw device may advantageously be used for locking any desired frame components, citing, solely by way of example, the screws for articulation

hinges for the arms, the screws for clamping the rim-closing "tubes" in metal frames, the screws coupled with bushes (provided with a threaded hole) for fixing metallic components on parts made of plastics (metal items fitted on lenses of plastics material, metal trims fixed on frames made of plastics), or the screws coupled to corresponding clamping nuts for fixing any desired component of the spectacles to other frame parts.