DESCRIPTION

FIELD OF THE INVENTION

The present invention concerns a method and system for the manufacturing and assembling of a frame for glasses, and in particular a wooden frame.

STATE OF THE PRIOR ART

In the glasses frames made of rigid, inextensible materials, intended for the use with ophthalmic lenses, it is customary, in order to facilitate the introduction/removal of the lens, to open and close each frame circle according to known methods, by now state of the art.

More precisely, in frames made of high-resistance metal or plastic materials, such operation consists in providing a sub- stantially radial cut or interruption on each circle, in particular at the level of the connection area of the temple bars, and in providing a joining element which then allows to close back clamp-like the open ends of the circle, after having mounted the lens. Typically, said clamp-like mounting is achieved by using a screw, which couples with a female screw obtained directly in one of the two ends of the frame circle.

However, inextensible, rigid materials exist which do not have mechanical features such as to allow a threaded hole to be made with sufficient guarantee of integrity during the screw tightening step. As a matter of fact, the tightening screw is by its very nature tiny and hence the threading has a very small pitch and size, which require a corresponding female screw with good precision.

One of these inadequate materials, for example, is wood, which is not suitable for the manufacture of small threaded holes and with fine threading pitch.

This disadvantage is one of the elements which in actual fact has so far prevented the industrial manufacture of glasses with a wooden frame.

PROBLEM AND SOLUTION

The problem at the core of the invention is overcoming the above-cited disadvantage, supplying a technical solution of a tightening clamp which, on the one hand, improves the operating conditions of the screw, during the tightening operation and, on the other hand, guarantees a sufficient integrity of the threaded hole for the entire life span of the frame, even when it is made of a yielding material such as wood.

SUMMARY OF THE INVENTION

This object is achieved through the features mentioned in the independent claims herewith attached. The dependent claims describe preferred features of the invention.

In particular, according to a first aspect of the invention, a manufacturing method of a wooden frame for glasses is provided, comprising the steps of

carving a wooden frontpiece comprising two lens-housing circles, providing opening/closing portions of the frontpiece whereon to arrange joining means comprising at least one screw, separate said opening/closing portions into two opposite half-portions to at least partly open said lens-housing circles, apply said joining means, wherein furthermore

at least one housing hole is practised which affects both said opposite half-portions of said opening/closing portions, and at least the hole of one of said opposite half-portions is equipped with an internally-threaded bush, which is part of said joining means, having a female screw for the engagement with said screw.

According to a further aspect of the invention, the internally-threaded bush is made of a strong material and is applied by cold joint or gluing. Preferably the internally-threaded bush has a knurled or furrowed outer surface.

According to a different aspect, said internally-threaded bush is obtained by in situ casting of plastic material or of a material made of hardening resin and subsequently processed to obtain a female screw for the engagement of said screw.

According to a further aspect of the method, the step of providing the hole of one of said opposite half-portions with a threaded bush, is performed after said step of separating said opening/closing portions of the frontpiece into two opposite half-portions .

Alternatively, said step of equipping said hole with a threaded bush is performed before the step of separating said frontpiece opening/closing portions into two opposite half- portions, said separating action providing also the separation of said bush in a more internal portion provided with female thread and engaged with a one of said opposite half-portions and a more external portion with a through-hole and engaged with the other one of said opposite half-portions.

According to an aspect of the invention, the frontpiece opening/closing portions consist of end pieces at the two outer sides of the two frontpiece circles, on said end pieces the temple bars of the frame being coupled.

According to an alternative or additional aspect to the one here above, the frontpiece opening/closing portions consist of a bridge connecting the two frontpiece circles, which is longitudinally separated from side to side.

According to another aspect of the invention, a wooden frame for glasses is provided, manufactured with a method as described above. Preferably the wooden material consists of a poplar or birch tree.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention are in any case more evident from the following detailed description of some preferred embodiments, given purely by way of a non- limiting example and illustrated in the attached drawings, wherein :

fig. 1 is a cross-section, according to a lying plane of a lens, of a frame shape according to the prior art, which may be used with rigid materials having suitable features of mechanical resistance;

fig. 2 is a cross-section fully similar to the one of fig. 1, concerning a first embodiment of a frame according to the in- vention; and

figs. 3 to 5 are cross-sections fully similar to the one of fig. 1, concerning a second embodiment of a frame according to the invention, in subsequent processing steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 shows schematically a prior-art frame, for example a metal or strong, rigid, synthetic-material frame, of which only a circle 1 is shown, provided at an outer end with a stalk or endpiece 2 for the attachment of a temple bar (not shown) and, on the inner side, with an extension 3 forming a bridge for attaching a nose pad arrangement .

According to the prior art, in correspondence of stalk 2 or of another area of suitable thickness, the frame circle is open along two abutment planes 4. This opening determines two opposite ends 2a, 2b of the circle, which are mutually spaced apart and which can, with a slight bending of the circle, be spread apart to allow the introduction of the lens (not shown) into the housing groove (also not shown) in the circle, or be brought mutually closer and tightened one on the other in order to lock the lens in position.

In order to allow the locking, in end 2a there is formed a threaded hole 5 and in end 2b there is formed a hole 6, wide enough to allow the introduction, with slight play, of a tightening screw 7. Preferably, hole 6 widens into a counter-hole at the upper end thereof, suited to form a housing 6a for the head 7a of screw 7. By screwing screw 7 in threaded hole 5 one ob- tains, upon resting head 7a in housing 6a, the desired tightening of the two ends 2a and 2b one against the other, which abut along the planes defined by opening 4.

However, one such arrangement cannot be used in the case of materials - as indeed wood - which do not have a sufficiently compact and strong structure to allow the carrying out of a fine thread, with a fine pitch, in hole 5, as necessary according to the prior art, taking into account the very small section size of frame 1 and of stalk 2. As a matter of fact, typically the screws which may be used in this sector are of a metric type Ml,2-Ml,4 with pitch 0,20-0,25 mm.

According to the invention, a frame 10 of wooden material (poplar and birch for example are particularly suited) is provided, equipped with two integral circles for the lenses, provided at the two outer ends with respective larger-thickness end pieces 20. According to a first embodiment of the invention, it is provided to open the circles of frame 1 in correspondence of the two end pieces 20, practising a cut which originates two opposite planes 24a and 24b. Subsequently it is provided to open the circle, typically mutually displacing axially offset the two ends 20a and 20b wherein end piece 20 remains separated. Thereby the two planes 20a and 20ba are exposed and it is possible to access them with a suited tool. Typically, on lower plane 20a (lower with reference to the attitude of the frame during use) , it is proceeded to practice a smooth hole with a diameter larger than the one of the female thread which it is intended to obtain for a fastening screw 27; the hole is preferably of a diameter larger by about 40%-50% with respect to the nominal diameter of the female thread, for example a hole ranging between about 1,8 mm and 2 , 2 mm.

Within the smooth hole a metal bush 28 is engaged. Metal bush 28 is fastened in the hole by cold forcing or with the help of glue means or hardening resins. In a variant it may be provided to introduce a bush having a knurled outer surface (in a radial or longitudinal direction) or more simply equipped with axial grooves, which simplifies all these fastening forms.

Alternatively, the fastening of bush 28 in the corresponding hole may be obtained by carrying out, on the outer surface thereof, a thread with a large pitch, such as "wood screw", for example ranging between 0,5 and 1 mm, the length of the bush permitting.

Bush 28 is in turn provided with a threaded inner hole, which defines the female thread which screw 27 is intended to engage with.

In a further variant, the bush is not separated and then applied, like metal bush 28, but is obtained by casting of a resin, or in general a high-resistance glue, directly in the hole of plane 20a. After the casting and hardening of this bush obtained in situ, it is provided to pierce the female thread directly with a threading tool (fine threading, suited to screw 27, which is borne well by the casting material), after having performed a hole of a suitable diameter.

All the above-mentioned solutions provide the introduction or the definition of a bush with a threaded hole, after the cut in the material of end piece 20 has been performed.

After the hole-making for the bush introduction, on the opposite side 20b of end piece 20 a through-hole is pierced for the in- troduction of a screw 27. In this case too, as in the prior art, the through-hole may provide an end counter-hole for the housing of the head of screw 27. Possibly also in this through-hole a smooth bush may be introduced for hole protection.

According to a different preferred embodiment of the inven- tion (figs. 3 -5 ) , it is provided instead to practise a single perforation 20', in the end pieces 20, on the wooden frame with the circles of the lenses still integral.

Once a blind, single-diameter perforation 20' has been carried out, it is provided to introduce a single integral bush 21, provided with an inner hole which has a more internal threaded part 11a and a more external smooth part lib, in the proximity of the mouth of bush 21, having a larger inner diameter.

This integral bush 21 is fastened in seat 20' with one of the three fastening techniques illustrated in the preceding sec- tion for bush 28, in particular by tight engagement and cold interference fit and/or with gluing means or screwed. At the end of the mounting thereof, it is arranged securely fastened, as shown in fig. 4.

At the end of this mounting, it is provided to perform a severing cut of end piece 20, so as to define the two opposite end portions 20a and 20b; in this cutting operation, also bush 21 is affected: thereby, bush 21 is divided into two distinct parts, i.e. a threaded part 21a, which remains in the lower end 20a of end piece 20 of frame 1, and an unthreaded part 21b, but with a through-hole, which remains in the upper end 20b of end piece 20. As in the previous embodiment, the two circle por- tions, thus separated, can be slightly spread apart to introduce the lens and then be mutually tightened with a screw 27.

This second embodiment is particularly advantageous because it simplifies mounting operations, it improves alignment preci- sion of the threaded hole for the introduction of screw 27 and it does not force to perform machining operations on the two portions of "open circle which are potentially risky for the integrity of the frame (especially if having a small thickness) .

The bush, also in this case, may be obtained by casting of plastic material or made of resin directly in hole 20'.

A further embodiment, not specifically illustrated, provides to practise a single cut or opening of the circles of the lenses (instead of two separate ones as in the preceding embodiments) , in correspondence of the bridge portion 3 of the nose area. In this case, a longitudinal cut is practised in the bridge portion, which cuts across it from side to side until it opens also the opposite circles. Since the cut or opening is only one on the frame frontpiece, it is sufficient to then mount a single threaded bush to introduce a single tightening screw; this does not prevent two bushes with corresponding tightening screws from also being provided, should other technical and/or aesthetic reasons exist which make it suitable.

However, it is understood that the invention must not be considered limited to the particular arrangements illustrated above, which represent only some exemplifying embodiments thereof, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of protection of the invention, as defined by the following claims .

In particular, although reference has been made to an adjoined metal bush, the use of other strong materials is not ruled out, such as plastic or composite materials.

Finally, it is not ruled out that the configuration of screw and bush may be turned upside down with respect to the one il- lustrated, i.e. with introduction of the screw from below (with reference to the attitude of the frame in use) .