ES1228249U - SUPPORT FOR OPHTHALMIC PREFORMS (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Support (1) for ophthalmic preforms (P) comprising a part (11) for fixing the preform (P) provided with a surface (S11) complementary to the surface (SI) of the preform (P), and a anchoring part (12) to an external structure of a treatment station, characterized in that it comprises a deformable envelope (13) attached on one side to the fixing part (11) of the preform (P) and on the other hand to the part (12) anchoring to an external structure, defining between the attachment part (11) of the preform (P), the anchoring part (12) to an external structure and the deformable envelope (13) a volume filled with a material (14) whose melting temperature is lower than the melting temperatures of the fixing part (11) of the preform (P), the anchoring part (12) to an external structure and the deformable casing (13). (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

SUPPORT FOR OPHTHALMIC PREFORMS

TECHNICAL SECTOR

The present invention relates to support for ophthalmic preforms intended to constitute a rigid anchoring of the preforms for their machining. Specifically, it refers to a support that minimizes the management needs of the thermofusible filling commonly used as a component for positioning the preform in the machining station.

BACKGROUND

The supports for ophthalmic preforms are already known in the state of the art. These supports have two functions, a first function of fixing the preform for its machining and a second function of variable positioning of the preform, to optimize the machining process.

For this the known supports, such as those illustrated in figures 1 to 3, are provided with a part A1 for fixing the preform P and an anchoring part 12 to an external structure of a treatment station, such as a station for example. of machining or a polishing station.

The classic solution for the support consists of molding, by means of a hot-melt metal alloy at low temperature, a connection between the anchoring part and the preform.

For this, an installation provided with at least one cavity is used, in whose bottom the anchoring part is arranged (for its later anchoring in the machining station), and whose area adjacent to the entrance opening is provided with several flanges for the colocation (with minimum play) of the preform that will be joined to the anchoring part. Once this placement or positioning, which will depend on how the preform was treated later, the molten alloy is poured into the volume delimited by the cavity, the anchoring part and the preform, being joined with the desired positioning with the part of anchorage.

The preform is not directly in contact with the alloy, since between both the placement of a film F is foreseen, as shown in figure 1.

This solution based on the use of a hot melt alloy at low temperature offers very good performance in regard to the fixation, it is effective to resist the high forces that occur during machining, and also has a high rigidity, which avoids unwanted vibrations and guarantees the precision of the machining with precisions of the micrometer order.

It should be noted that this rigidity is crucial for obtaining a lens with the desired curvature, because if this phase is not done well, the obtained lens must be discarded and start again from scratch. It should also be noted that this is a sector in which obtaining the first product is essential, because it is a product of first necessity for end customers, and it is also a fundamental claim for optical stores .

Now, a disadvantage of the use of malleable alloys is the need to manage the flow of the alloy material, since it circulates from a feed tank, it is molded together with the preform, to be cooled, to be carried along with the preform and anchoring by different stations, the last being the de-anchoring station, in which the alloy is melted again to release the lens. This alloy must be adequately treated in safety conditions to be taken back after some stages of recovery, until the blocking station.

Another solution known in the market is based on the use of supports made of plastic material such as those shown in figures 2 and 3.

This solution consists in that the support is a single piece provided with three sections, as shown in figure 2. A lower section S2 of anchor, whose shape is standard in a similar way to the solution based on alloys, a section S3 of fixation to the preform P, and a transition section between both.

The effective fixation between preform P and support is achieved by a plastic adhesive disposed between the preform and the support.

This solution has the advantage that the cycle of utilization of the alloy is avoided, this being its main virtue.

However, this entails drawbacks that far exceed its virtues. In the first place, supports of different formats must be provided, adapted to each curvature of the preform.

In addition, a very strong adhesive must be used, which, although it allows to achieve the effective fixation, then it must be removed, which is a complicated and delicate operation that also leaves in many cases remains of adhesive, which implies in turn a stage additional verification and eventual additional polishing. During this phase it can also happen that the lens breaks, because it is a stage that involves high forces.

Another drawback is that, unlike the alloy, the plastic support can not be reused, as its diameter coincides with that of the preform and is often also machined together with the preform. Therefore, this solution involves the management of plastic waste.

Finally, another drawback of this solution is that the resulting union between the preform and the machining station has a certain elasticity, which negatively affects the final result, specifically the precision of the machined surface.

DESCRIPTION OF THE INVENTION

To overcome the drawbacks of the state of the art, the present invention proposes a support for ophthalmic preforms comprising a fixation part of the preform provided with a surface complementary to the surface of the preform, and an anchoring portion to an external structure of the preform. a treatment station, comprising a deformable envelope attached on one side to the fixing part of the preform and on the other hand to the anchoring part to an external structure, defining between the fixing part of the preform, the anchoring part to an external structure and the deformable envelope a volume filled with a material whose melting temperature is lower than the melting temperatures of the fixing part of the preform, the anchoring part to a external structure and the deformable envelope.

This solution solves the drawbacks of the state of the art. As the alloy remains encapsulated, its utilization cycle is greatly simplified, since it is simply reused together with the anchoring part. In this way alloy management only occurs in the supply and when it ends its useful life, which also extends considerably, by not being exposed to the outside. The filling material can be an alloy, which is usually easily oxidizable, so that the increase in useful life when encapsulated is very important.

An appreciable advantage of the invention is that the alloy is used to perform the function of rigid positioning. Furthermore, its use as a rigid positioning component can be combined with a function of direct attachment to the preform, or it can be combined with the use of a fixation part of the preform provided with the curvature suitable for each type of preform. In this case, the advantages of the two known solutions are combined.

The aforementioned realization of direct fixation is that the upper encapsulation of the alloy is in contact with the preform, so that it performs the function of the protection film.

In some embodiments, the fixing part of the preform is a single metal, polymeric, ceramic or glassy part.

In this case it should be foreseen that the treatment stations have a set of fixation parts with the different standardized curvatures, as well as the standardized contours of positioning in the positioning station, that is to say the station in which the fusion is carried out and Freezing of the alloy, and replacing the previous alloy pouring station.

In some embodiments, the fixation part of the preform is composed of two mutually embedded components:

- a first of them provided with the surface complementary to the surface of the preform and intended to be in contact with the preform; Y

- the second intended to be attached to the deformable envelope.

In this embodiment, it can be foreseen that the first component is made of a thermoplastic material and that the second component is metal. In this way, the first component can have a diameter substantially equal to the lens, so that a fixation of the preform is achieved on practically all its rear surface (that which is not machined), which in turn provides a support resistant to the entire preform for its machining, especially reducing unwanted overhangs.

In some embodiments, the support comprises reversible joining means between the two components, the joining means preferably being threaded.

In some embodiments, the deformable shell is made of polymer or elastomer.

In some embodiments, the deformable envelope is a metal bellows.

In some embodiments the deformable casing is a ford, watertight bellows. On the one hand, the inventors have verified that this type of bellows satisfies the needs of the invention, since it provides an effective contention from the mechanical and sealing point of view, and on the other hand it is a commercially available component and of reduced cost .

In some embodiments the anchoring portion to an external structure is metallic and has a standard fastening profile.

In some embodiments the surface of the fixation part complementary to the convex surface of the preform is rough or is etched with a pattern, so that the fixation of the preform is improved.

In some embodiments, the anchoring portion comprises heating means for supplying heat to the alloy. Therefore, for the fusion of the alloy, it is sufficient to provide terminals in the fixation station of the preform to provide energy to the hot melt material.

In some embodiments, the anchoring portion comprises cooling means for supplying cold to the alloy.

In some embodiments the filling material is an alloy, a wax or a thermoplastic with low melting point, preferably between 40 and 60 ° C.

The invention also relates to a method of positioning and fixing an ophthalmic preform to a support, for the subsequent attachment thereof to an external structure of a machining station, comprising the steps consisting of:

a) providing a support for ophthalmic preforms comprising a fixation part of the preform provided with a surface complementary to the convex surface of the preform, and an anchoring portion to an external structure of a machining station, comprising a deformable enclosure attached on the one hand to the fixing part of the preform and on the other hand to the anchoring part to an external structure, defining between the fixing part of the preform, the anchoring part to an external structure and the deformable envelope a filled volume of an alloy whose melting temperature is lower than the melting temperatures of the fixing part of the preform, the anchoring part to an external structure and the deformable envelope;

b) fixing the ophthalmic preform to the convex surface;

c) anchoring the assembly obtained in stage b) to the external structure;

d) melting the alloy;

e) positioning the assembly constituted by the fixing part of the preform and the preform with respect to the external structure with a view to leaving it with the desired position for machining.

Preferably, step b) is carried out with interposition of a film and an adhesive, the adhesive preferably being a wax, an adhesive or a thermoplastic.

BRIEF DESCRIPTION OF THE DRAWINGS

To complement the description and in order to help a better understanding of the characteristics of the invention, according to examples of practical realization of the structure, a set of figures is included as an integral part of the description, in which illustrative and not limiting, the following has been represented:

Figure 1 shows a support of the state of the art constituted by a part of anchoring and an alloy molding that fixes the preform with interposition of a protection film.

Figure 2 shows in perspective a set of preform and preform support, where the latter is made of plastic.

Figure 3 shows the support of figure 3 but seen from the bottom.

Figure 4 is a section of a support according to a realization of the invention.

Figure 5 shows a preform and support assembly according to an embodiment of the invention in which the support is implemented with a forging metal bellows.

Figure 6 is a perspective view of the support of Figure 5 but from another point of view.

Figure 7 is a perspective view of another embodiment in which the encapsulation of the alloy is carried out with a polymeric or elastomeric material.

Figure 8 shows a section through a meridian plane of an embodiment in which the support part is in turn composed of two parts, a part of attachment to the alloy, of metal, and a part of plastic, which can be a part of sacrifice.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Figure 4 shows a section of a support 1 for ophthalmic preforms P according to the invention.

The support comprises a part 11 for fixing the preform P provided with a surface S11 complementary to the surface SI of the preform P, in this case concave, although in other embodiments it could be convex, or even flat.

The support also comprises an anchoring part 12 to an external structure of a treatment station, typically a machining or polishing station.

According to the invention, the support comprises a deformable envelope 13 joined on one side to the fixing part 11 of the preform P and on the other hand to the anchoring part 12 to an external structure.

Between the fixing part 11 of the preform P, the anchoring part 12 to an external structure and the deformable envelope 13 is defined a filled volume of an alloy 14 whose melting temperature is lower than the melting temperatures of part 11 of fixing the preform P, the anchoring part 12 to an external structure and the deformable envelope 13.

In this way a compact assembly is obtained which avoids the transfer and degradation of the alloy 14, which is encapsulated.

The fixing part 11 of the preform P can be a single metallic, polymeric, ceramic or glassy part.

Although, as shown in Fig. 8, it is preferred that the fastening portion 11 of the preform P is composed of two mutually-engaged components 111, 112:

- a first one of them provided with the surface S11 complementary to the surface SI of the preform P and intended to be in contact with the preform P; Y

- the second 112 intended to be attached to the deformable envelope 13.

In this way, the first component 111 can be a sacrificial part, preferably of thermoplastic material, which can be machined if necessary to cut out lens parts inscribed on the support surface of the fixing part.

Reversible joining means are also provided between the two components, the joining means being preferably by threading, as shown in FIG. 8.

As regards the deformable envelope 13, this can be constituted by a metal bellows or else be made of polymer or elastomer.

The first of the options can be implemented by means of a forged, sealed bellows, of the type commercially available in the market at a low cost. This option has been represented in figures 5 and 6, which show a practical and operational realization of the invention A h can be seen metal bellows 13, which is deformable when the alloy that has encapsulated is at a temperature greater than its melting temperature. In contrast, the fastening parts 11 and 12 are not deformable and have functions of attachment to the preform and anchoring to the treatment station respectively.

In some embodiments, the surface S11 of the fixing part 11 complementary to the convex surface SI of the preform P is rough or is engraved with a pattern. In this way, when filling the spaces (preferably mm) existing between the preform P and the surface S11 by means of a wax, a thermoplastic or an adhesive, an anchoring with the necessary resistance for the machining can be achieved.

In Figure 4 a realization is shown whose anchoring part 12 may comprise heating means 15 for supplying heat to the alloy 14. This part may also constitute a cooling means 15 for supplying cold to the alloy 14.

In this way, the support can be provided with the thermal means necessary to further reduce the time of fusion and solidification of the alloy for the process of positioning and fixing the preform with respect to the anchoring part 12.

The invention also relates to a method of positioning and fixing an ophthalmic preform P to a support 1, for the subsequent attachment thereof to an external structure of a machining station, comprising the steps consisting of:

to provide a support 1 for ophthalmic preforms P comprising a fastening portion 11 of the preform P provided with a surface S11 complementary to the convex surface SI of the preform P, and an anchoring portion 12 to an external structure of a station machined, comprises a deformable envelope 13 attached on one side to the fixing part 11 of the preform P and on the other hand to the anchoring part 12 to an external structure, defining between the fixing part 11 of the preform P, the part 12 anchoring to an external structure and the deformable envelope 13 a volume filled with an alloy 14 whose melting temperature is lower than the melting temperatures of the fixing part 11 of the preform P, the anchoring part 12 to an external structure and the deformable envelope 13;

b fix the preform P ophthalmic to the convex surface SI;

c anchoring the set obtained in stage b to the external structure;

d melting alloy 14;

and positioning the assembly constituted by the fixing part 11 of the preform P and the preform P with respect to the external structure with a view to leaving it with the desired position for machining.

Step b is carried out with interposition of a film F and an adhesive, the adhesive preferably being a wax.

In a process in which it is necessary to be able to mechanise jointly the preform P and the sacrificial attachment part 11, it is provided that the latter is constituted by a component provided with the surface S11 complementary to the surface SI of the preform P and intended to be in contact with the preform P, and a second 112 intended to be attached to the deformable envelope 13.

Therefore, in this case, a previous stage of mutual fitting between these components 111, 112 must be provided.

In this text, the word "comprises" and its variants (such as "understanding", etc.) should not be interpreted in an exclusive manner, that is, they do not exclude the possibility that the description includes other elements, steps, etc.

On the other hand, the invention is not limited to the specific embodiments that have been described but also covers, for example, the variants that can be made by the average expert in the field, within what is clear from the claims.

Claims (13)

1. - Support (1) for ophthalmic preforms (P) comprising a part (11) for fixing the preform (P) provided with a surface (S11) complementary to the surface (SI) of the preform (P), and an anchoring part (12) to an external structure of a treatment station, characterized in that it comprises a deformable envelope (13) joined on one side to the fixing part (11) of the preform (P) and on the other hand to the anchoring part (12) to an external structure, defining between the fixing part (11) of the preform (P), the anchoring part (12) to an external structure and the deformable envelope (13) a volume filled with a material (14) whose melting temperature is lower than the melting temperatures of the fixing part (11) of the preform (P), the anchoring part (12) to an external structure and the deformable casing (13). 2. - Support (1) according to claim 1, wherein the part (11) of fastening the preform (P) is a single piece metal, polymeric, ceramic or glassy. 3. - Support (1) according to claim 1, wherein the part (11) of fixing the preform (P) is composed of two mutually embedded components (111, 112): - a first (111) of them provided with the surface (S11) complementary to the surface (SI) of the preform (P) and intended to be in contact with the preform (P); Y - the second (112) intended to be attached to the deformable envelope (13). 4. - Support (1) according to claim 3, wherein the first component (111) is a thermoplastic material and the second component (112) is metal. 5. - Support (1) according to claim 3 or claim 4, comprising reversible joining means between the two components, the joining means preferably being threaded. 6. - Support (1) according to any of the preceding claims, wherein the deformable casing (13) is made of polymer or elastomer. 7. - Support (1) according to any of claims 1 to 5, wherein the deformable casing (13) is a metal bellows. 8. - Support (1) according to claim 7, wherein the deformable casing (13) is a ford bellows, hermetic. Support (1) according to any of the preceding claims, wherein the part (12) anchoring to an external structure is metal and has a standard fastening profile. 10. - Support (1) according to any of the preceding claims, wherein the filling material (14) is an alloy, a wax or a thermoplastic with low melting point, preferably between 40 and 60 ° C. 11. - Support according to any of the preceding claims, wherein the surface (S11) of the fixing part (11) complementary to the convex surface (SI) of the preform (P) is rough or is engraved with a pattern . 12- Support according to any of the preceding claims, wherein the anchoring part (12) comprises heating means (15) to supply heat to the alloy (14). 13. Support according to any of the preceding claims, wherein the anchoring part (12) comprises cooling means (15) to supply cold to the alloy (14).