WO2006045965A1 - Method for finishing or correction of the profile of the periphery of an ophthalmic lens following an edge profile - Google Patents

Abstract

The invention relates to a method for finishing or correction of the profile of the periphery of an ophthalmic lens (L) following an edge profile, comprising at least one finishing or correction machining step of a part (B2) of the profile of the edge of the lens with a pass depth limited by abutting another part (P2) of the profile against a stop element (99).

Description

 METHOD OF FINISHING OR RETOUCHING DETOURING THE PERIPHERY OF AN OPHTHALMIC LENS ACCORDING TO A SONG

PROFILE

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to the mounting of ophthalmic lenses of a pair of corrective eyeglasses on a frame and more particularly to a method and a tool for working the periphery of an ophthalmic lens. a pair of spectacles, as well as a device for trimming an ophthalmic lens incorporating such a working tool.

The invention finds a particularly advantageous application for retouching edging of the edge of a lens after a first machining.

TECHNOLOGICAL BACKGROUND The trimming of a lens for mounting in a circular mount chosen by the future carrier is to change the contour of the lens to fit the shape and dimensions to this frame. The trimming includes the edging for shaping the periphery of the lens and, when the mounting is of the rim type, the beveling which is a finishing step of providing the formation of a rib, usually called bevel, on the slice of the lens. This bevel, which generally has a V-shaped section or profile, is intended to be engaged in a corresponding groove, commonly known as a bezel, formed in the circle or surround of the eyeglass frame in which the lens is to be mounted. The trimming must also take into account the morphology of the user, so that the lenses of the pair of glasses are, in use, properly positioned (ie centered and oriented) facing the eyes of the wearer to exercise accurately the optical function for which they were designed and manufactured. For this purpose, the optician must perform a number of measurement and / or registration operations on the lens itself, before trimming, to identify some of its characteristics such as the optical center in the case of a lens unifocal or mounting cross in the case of a progressive lens, or the direction of the axis of progression and the position of the centering point for a progressive lens. In practice, each lens is generally delivered by the manufacturer with marks on its convex front face, some of which are representations of a centering repository of the lens. If these marks are absent or are not sufficiently visible, the optician defers certain characteristic points with a sharp point on the ophthalmic lens itself. These marks are used to position and fix on the lens an adapter or acorn centering and drive to properly position the ophthalmic lens in the grinding machine to give it the desired contour, corresponding to the shape of the frame chosen. The operation of positioning and depositing the glans, can be performed manually or automatically, with a device called centering-blocker.

Anyway, this glans is most often stuck temporarily on the lens with a double-sided adhesive. This operation is usually called the centering of the lens, or by blocking extension of the lens since the glans can then block, that is to say immobilize, the lens on the means of its trimming in a known geometric configuration thanks to this acorn.

After placing the centering glue, the lens thus equipped is then placed in the clipping machine where it is given the shape corresponding to that of the chosen frame. The centering glide makes it possible to define and physically materialize on the lens a geometric reference frame in which the points and the characteristic directions of the lens, necessary for the coherence of this lens with the position of the pupil, and the values are identified. of clipping so that these points and characteristic directions are properly positioned in the frame.

retouche.When the trimming of the lens does not result in a first fitting in the mount, the operator resumes machining. To do this, it puts the lens in the machine and blocks it with the same tassel, which allows to recover the initial clipping repository. He then proceeds to a clipping of everything

retouching.

However, the use of a glued acorn is a disadvantage in that it must be removed after mounting the lens, which is time consuming and labor intensive. In addition, the lens is secured to the glans by bonding which can lead to intensive cleaning of the lens surface after treatment, leading to a risk of deterioration of the coating layer or scratch. Finally, these operations of laying and removal of the glans being relatively complex and delicate, they require a qualified and careful workmanship and are in practice time-consuming and therefore expensive; and for the same reasons, it is difficult to automate them.

Thus, in the context of this research work, the applicant wishes to overcome the centering by glans because of the aforementioned constraints. Moreover, it often happens that the optician does not itself proceed to the trimming of the lens, but orders the manufacturer of lenses already cut with their bevel to the shape and dimensions, given the data on the frame, the prescription and morphology of the wearer that it provides to the manufacturer. The latter then delivers to the optician cut-out lenses devoid of any acorn or analog materializing its optical reference.

Finally, in the current practice of selling glasses, the lenses are often detached from their machining glans before being installed on their mount for a fitting.

In all these hypotheses, one runs the risk that a clipping defect is found while the glans embodying the clipping frame has been detached from the lens. The optician must then resume trimming with a second machining. However, to resume the machining correctly, it would be necessary to replace the lens in the real center of reference of the first machining so that, on the one hand, the radial and axial geometrical configuration of the periphery of the lens is known in the reference frame of the the trimming machine and that, on the other hand, the trimming face of the grinding wheel is well parallel to the edge of the lens to resume.

A first solution consists of retouching judged by the optician, the lens being re-locked according to any axis and the optician manually carrying out an approximate measurement of all or part of the lens. of the lens. In addition to the know-how that this method requires, it has the major disadvantage of requiring great attention to detail, costly in working time, otherwise the lens incurs inaccurate assembly or even scrapping. Another solution is to recalculate by optical measurements, before the second machining, the theoretical centering reference of the lens. But the inaccuracies of these optical measurements have the consequence that the centering reference obtained in this second machining step differs slightly from the first theoretical reference used during the first machining step. Moreover, in addition to these optical measurement inaccuracies, inaccuracies of locking of the lens by the locking noses of the clamping shafts. The second centering reference obtained is therefore different from the first one in which it is desirable to go back for retouching. This results in a radial and axial positioning error of the lens relative to the grinding wheel during this second machining. In addition, the lens being off-center with respect to its centering position of the first machining, and taking into account the curvature of the lens, the edge of the lens is inclined with respect to the edging face of the grinding wheel. Thus machining in this configuration, can not achieve the desired shape and radius values for the edge of the lens and in particular its bevel. In addition, this locking repository re-acquisition solution is time consuming for a skilled workforce and / or sophisticated devices.

In addition, for a lens having a bevel, the positioning error and inclination of the lens relative to the grinding wheel has the consequence that, during retouching, the edging face of the wheel grinds the bevel erratically .

OBJECT OF THE INVENTION

An object of the present invention is to provide a finishing method of clipping, including retouching, a lens, which is precise and respectful of the shape of the edge of the lens without it being necessary to perform time consuming measurements to know the precise geometrical configuration of the edge of the lens in the repository of the trimming machine.

For this purpose, it is proposed according to the invention a finishing process or re_touche_de _. _DétQLurage_d_a_a_a_peripheral_de_a ophthalmic lens according to_a_cant_bant_ profiled, comprising at least a step of machining finishing or retouching of a portion of the profile of the edge of the lens with a depth of pass limited by an abutment of another part of said profile against a stop element. According to advantageous features of the invention:

the song to be made of the lens has a bevel;

said other part which is abutted corresponds to at least a part of the bevel; - said other part which is abutted corresponds to at least a portion of the bevel foot;

the finishing or retouching machining step of a portion of the profile of the edge of the lens is repeated several times with a depth of pass limited by an abutment in order to achieve a reduction in the radius values of the edge of the the lens of a predefined multiple of the depth of pass;

- Finishing machining or retouching being performed by means of a profiled tool rotatably mounted about an axis of rotation, said stop member is constituted by an inactive smooth portion of the tool;

- Finishing or retouching machining is performed by means of a tool which is rotatably mounted about an axis of rotation and which has during machining finishing or retouching at least, in addition to its rotation about said axis rotation, a free translational mobility having at least one component parallel to its axis of rotation;

- Finishing or retouching machining is performed by means of a tool which is rotatably mounted about an axis of rotation and which has during machining finishing or retouching at least, in addition to its rotation about said axis rotation, a tilting mobility with two degrees of freedom around two distinct pivotal directions substantially transverse to its axis of rotation;

- The tool is recalled, in its pivoting about its pivoting directions, in a return position;

the method is applied to a retouching of the trimming of the edge of the lens after a prior trimming.

premier référentiel de centrage,In an advantageous embodiment, the method comprises the following preliminary steps:

first reference centering,

- after the preliminary machining, the lens is unlocked with loss of the centering reference, - Before finishing machining or retouching, the lens is locked again without necessarily being centered by reacquisition of a centering repository.

In an advantageous embodiment, the method comprises:

a first step of machining finishing or retouching of a first portion of the profile of the edge of the lens with a depth of pass limited by an abutment of a second portion of said profile against a stop element,

a second step of machining finishing or retouching of the second part of the profile of the edge of the lens with a depth of pass limited by an abutment of the first part of said profile against a stop element. Advantageously then the first part and the second part of the profile of the edge of the lens are complementary to form the whole of said profile.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings of the various embodiments, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be achieved. In the accompanying drawings: FIG. 1 is a general perspective view of a trimming device for carrying out the method according to the invention; FIG. 2 shows, from another angle and on a larger scale, the detail of FIG. 1 indicated by an inset II in this FIG. 1, showing the finishing tool according to a first embodiment of the invention; Figure 3 is a block diagram illustrating the tilting property of the tool during machining; Figure 4 is an axial sectional view of the finishing tool or retouching; FIGS. 6 to 9 are fragmentary diagrammatic sectional views of the lens and, for the views 6 and 9, of the finishing or retouching tool, illustrating the successive steps of the shaping of the lens, with FIGS. 6 and 7 a preliminary cut-out of the lens and in FIGS. 8 and 9, the retouching or finishing of the bevel of the lens in a single step is performed at a first stage _. odβ-realization of the method according to the invention; Figures 10 to 12 are partial schematic sectional views of the lens and, for the views 10 and 11, of the finishing tool or retouching, illustrating the successive steps of a finishing or retouching of the clipping lens, with machining in two steps on two separate grinding wheels according to a second embodiment of the method according to the invention.

In Figure 1 there is shown a device 10 for trimming for the implementation of a working method of the periphery of a lens L ophthalmic lens in accordance with the invention.

This is just an example. The trimming device 10 according to the invention can be made, as regards its general architecture, in the form of any cutting or material removal machine adapted to modify the contour of the ophthalmic lens L to adapt it to that of the frame or "circle" of a selected mount. Such a machine may consist for example of a grinder, as in the example described below, but also in a milling machine, turning or cutting laser or jet water, etc. For example, it is possible to use a grinder of the type of those marketed by the applicant under the trademark Kappa or described in document FR2784919. It is also possible to use a trimming machine having a "knife" type work tool such as those marketed by National Optronics, Charlottesville United States of America, and described in US5158422.

In the example illustrated in Figure 1, the device 10 of cutting comprises, in a manner known per se, an automatic grinder, commonly called digital. This grinder comprises, in this case, a rocker 11, which is freely pivotally mounted about a first axis A1, in practice a horizontal axis, on a frame 1.

For the immobilization and rotational drive of an ophthalmic lens such as L to be machined, the grinder is equipped with two clamping shafts 12, 13. These two shafts are aligned one with the other. another along a second axis A2, called the blocking axis, parallel to the first axis A1. The two shafts 12, 13 are rotated synchronously by a motor (not shown), via a common drive mechanism (not shown) on board Ja _. rocking _. This common synchronous rotation drive mechanism is of a conventional type, known in itself. Alternatively, it will also be possible to drive the two shafts by two separate motors synchronized mechanically or electronically. The rotation ROT of the shafts 12, 13 is controlled by a central electronic and computer system (not shown) such as an integrated microcomputer or a set of dedicated integrated circuits.

Each of the shafts 12, 13 has a free end which faces the other and which is equipped with a locking nose 62, 63. The two locking noses 62, 63 are generally of revolution about the axis A2 and each have an application face (not shown) generally transverse, arranged to bear against the corresponding face of the ophthalmic lens L.

In the example shown, the nose 62 is integral and is fixed without any degree of mobility, neither sliding nor rotating, on the free end of the shaft 12. The nose 63 comprises two parts: a pellet application 66 intended to cooperate with the lens L and carrying for this purpose a useful face (not shown) and a tail (not shown) arranged to cooperate with the free end of the shaft 13, as we shall see more in detail thereafter. The pellet 66 is attached to the tail 67 by a cardan link 68 transmitting rotation about the axis A2 but allowing the orientation of the pellet 66 about any axis perpendicular to the axis A2. The useful faces (not shown) of the noses are preferably covered with a thin plastic or elastomeric material gasket. The thickness of this lining is of the order of 1 to 2 mm. This is for example a flexible PV or a neoprene.

The shaft 13 is movable in translation along the blocking axis A2, facing the other shaft 12, to effect the compression in axial compression of the lens L between the two locking noses 62, 63. The shaft 13 is controlled for this axial translation by a drive motor via an actuating mechanism (not shown) controlled by the central electronic and computer system. The other shaft 12 is fixed in translation along the blocking axis A2.

The trimming device 10 comprises, on the other hand, a set of wheels 14, which is locked in rotation on a third axis A3 parallel to the first axis A1, and which is also properly driven in rotation by a motor 20. Eji_p / This is followed by coaxial mounting of the third axis A3 for roughing and finishing of the protrusion of the ophthalmic lens L to be machined. These different grinding wheels are each adapted to the material of the cut lens L and the type of operation performed (roughing, finishing, mineral or synthetic material, etc.). The train of main wheels 14 is attached to a common shaft axis A3 ensuring their rotation in the operation of edging. This common shaft, which is not visible in the figures, is controlled in rotation by the electric motor 20 controlled by the electronic and computer system. The train of main wheels 14 is also movable in translation along the axis A3 and is controlled in this translation by a drive motor. Specifically, the entire main wheel train 14, its shaft and its motor is carried by a carriage 21 which is itself mounted on slides 22 integral with the frame 1 to slide along the third axis A3. The translational movement of the grinding carriage 21 is called "transfer" and is denoted TRA. This transfer is controlled by a motorized drive mechanism (not shown), such as a screw and nut or rack system, controlled by the central electronic and computer system.

To allow a dynamic adjustment of the distance between the axis A3 of the grinding wheels 14 and the axis A2 of the lens L during the edging, the pivoting capacity of the rocker 11 is used around the axis A1. This pivoting causes in fact a displacement, here substantially vertical, of the lens L sandwiched between the shafts 12, 13 which brings the lens L closer to the grinding wheels 14. This mobility, which makes it possible to restore the shape of the desired and planned edging in the electronic and computer system, is called restitution and is noted RES in the figures. This RES restitution mobility is controlled by the central electronic and computer system.

As illustrated in Figure 1, the rocker 11 is directly articulated to the nut 17 mounted movably along the axis of restitution A5. A strain gauge is associated with the rocker to measure the machining advance force applied to the lens L. Thus, during the machining, the grinding force force applied to the lens L is constantly measured. and piloting the progression of the nut 17, and therefore of the rocker 11, so that this effort remains below a maximum setpoint value. This setpoint value is, for each lens L, adapted to the material and to the Jajforme de_cett_eJe_ntilie_L

For machining the ophthalmic lens L according to a given contour, it suffices, therefore, firstly to move the nut 17 accordingly along the fifth axis A5, under the control of the motor 19, to control the movement of restitution and, on the other hand, to jointly rotate the support shafts 12, 13 around the second axis A2, in practice under the control of the engine that controls them. The transverse restitution movement RES of the rocker 11 and the rotational movement ROT of the shafts 12, 13 of the lens L are controlled in coordination by an electronic and computer system (not shown), duly programmed for this purpose, so that all points of the contour of the ophthalmic lens are successively brought back to the correct diameter. At the same time, the transfer TRA is controlled by the electronic system for the axial tracking of the bevel, the groove or the chamfer by the grinding wheels.

The grinder further comprises a finishing module 25 which is movable according to a degree of mobility, in a direction substantially transverse to the axis

A2 of the trees 12, 13 for holding the lens L and the axis A5 of the restitution

RES. This degree of mobility is called retraction and is noted ESC in the figures.

In this case, this retraction consists of a pivoting of the finishing module 25 around the axis A3. Concretely, the module 25 is carried by a lever 26 secured to a tubular sleeve 27 mounted on the carriage 21 to pivot about the axis A3. For the control of its pivoting, the sleeve 27 is provided, at its end opposite the lever 26, a toothed wheel 28 which meshes with a pinion (not visible in the figures) fitted to the shaft of an electric motor 29 integral with the trolley 21. In summary, it can be observed that the degrees of mobility available on such a trimming grinder are: the rotation of the lens L making it possible to rotate the lens around its holding axis, which is generally normal to the general plane of the lens, the restitution, consisting of a transverse relative mobility of the lens L (that is to say in the general plane of the lens) with respect to the grinding wheels, making it possible to reproduce the different rays describing the contour of the desired shape of the lens L, the transfer, consisting of an axial relative mobility of the lens L (that is to say, perpendicular to the general plane of the lens) with respect to the grindstones 14, making it possible to position in yis ^ -yisja _^ lens J- andJa. grinding wheel chosen, and, during machining to follow the path of the bevel, groove or chamfer. the retraction, consisting of a transverse relative mobility, in a direction distinct from that of the restitution, of the finishing module 25 relative to the lens L, making it possible to put the finishing module 25 in the position of use and to store it.

In this context, the general object of the invention is to integrate in this grinder a finishing function and in particular retouching the work of the periphery of an ophthalmic lens L previously cut away.

After the first machining, the lens L is unlocked with loss of the centering reference. Then, before the second machining, the lens L is centered and locked again. However, because of the loss of the centering reference of the first machining there is always a centering gap between the first and the second machining. This gap generates a shift and a tilting of the lens L at the origin of a positioning error of the edge C of the lens L with respect to the retouching wheel 31.

As schematized in FIG. 1, the finishing module 25 of the grinder 10 comprises a tool 30 for working around the periphery of the ophthalmic lens L. This tool is mounted on the finishing module 25 of the device 10 for trimming the ophthalmic lens L. In addition, the finishing module 25 accommodating the working tool 30 is retractable in a plane substantially transverse to the axis A2 of the clamping shafts 12, 13 and for rotating the ophthalmic lens L. Thus, the work tool 30 also has a degree of ESC retraction mobility. The working tool 30 is rotated about its axis of rotation A4 by a motor (not shown).

The axis A4 of the work tool 30, mounted on the finisher 25, is inclined with respect to the axis A3.

For retouching the edging after a first machining, the working tool 30 comprises a retouching grinding wheel 31, a second grinding wheel known per se known as a creasing wheel 35, and a third grinding wheel referred to as a finishing grinding wheel 34.

As shown in FIG. 2, the retouching wheel 31 comprises a plurality of conical faces of revolution about the axis A4, with a bearing face 99 and two chamfering faces 33, 98. A bevelling groove 32 is formed by recessing the bearing face 31.

The bearing face 99 is smooth and therefore inactive in machining in that it has no abrasive power, but is instead designed to slide on the edge of the lens in work without affecting the surface with which she is in contact. It can also be provided for this purpose that the bearing surface 99 of the retouching wheel 31 is coated with a coating with a low coefficient of friction appropriate to the synthetic or mineral material of the lens. To be substantially parallel to the edge C of the lens L _1, the bearing face 99 of the retouching wheel 31 is conical. More specifically, the cone angle of the bearing face 99 substantially corresponds to the angle of inclination of the axis A4 of the tool 30.

The bevelling groove 32 has a generally V-shaped profile. This groove is intended for retouching the bevel B of the lens and is therefore active in machining in that it has an abrasive power.

The chamfering faces are also abrasive and therefore active in machining and are intended for chamfering the two sharp edges E1.E2 of the edge of the ophthalmic lens L overflowed. Their generatrices form an angle with the bearing face 99.

In FIG. 1 presenting the trimming device 10 and the tool 30, the

Comparison of the retouching wheel 31 mounted on the tool 30 with the main wheels mounted on the wheel set 14, shows that the diameter of the retouching wheel 31 is smaller than that of the main wheels of the wheel set 14 The use of the retouching wheel 31 characterized by a smaller diameter than that of the main wheels of the wheel set 14 makes it possible to

20 decrease the shearing of the bevel of the lens L occurring during working of the periphery of a lens L with one of the main mill wheels, especially for highly curved lenses.

As shown in the block diagram of FIG. 3, the retouching grinding wheel 31 is mounted on a support 38 for driving in rotation by means of

25 of a tilting spherical mechanical connection allowing free rotation M1 of the retouching wheel 31 relative to the support 38 around two distinct pivotal directions substantially transverse to the axis of revolution of the edging face 99 of the grinding wheel. retouching.

The retouching wheel 31 comprises a spherical connection, rigid _30_ _χadiajement. When it has left its edging face 99, the rigid spherical connection radially prevents the retouching wheel 31 from translating radially with respect to the carrier 38. . In addition, the working tool 30 comprises means for returning the retouching wheel 31 in a return position around its pivoting directions. This restoring position of the retouching wheel 31 is such that the axis of revolution of its edging face 99 coincides with the axis of rotation A4 5 of the retouching wheel. The support 38 constitutes a drive shaft of the retouching wheel 31 having an axis of rotation substantially coinciding with the axis of revolution of the edging face 99 of the retouching wheel 31.

For driving in rotation of the retouching wheel 31, drive means are provided to ensure a torque transmission of the support

10 38 to the retouching wheel 31. These drive means are merged with the mechanical tilting connection means and are arranged to make a spherical mechanical finger connection, blocking the rotation of the retouching wheel 31 around its axis. A4 revolution with respect to the support 38.

FIG. 4 represents a first embodiment according to the invention of a

15 tool 3OA. In particular, the mechanical spherical finger connection comprises, on the one hand, a grooved ball 40 secured to the support 38 by means of a locking pin 50 in rotation, having a plurality of curved sections, and, on the other hand, on the other hand, a grooved housing 70 associated with the retouching grinding wheel 31A, having a plurality of panels, and arranged to cooperate with said splined ball 40.

More specifically, the ball 40 and the housing comprise flanges oriented in the direction of the axis of rotation A4 of the retouching wheel 31A. These sections block the retouching wheel 31A in rotation about the axis A4 relative to the support 38 on which it is mounted. This blocking rotation of the retouching wheel relative to the support then makes it possible to transmit the torque of the support

25 38 to the retouching wheel 31A. The transmission of torque causes the rotation of the retouching wheel around the axis of rotation A4. Advantageously, the curved sections of the ball 40 leaves the retouching wheel 31A free following the other two degrees of freedom in rotation which allows it to always adapt well to the edge C of the ophthalmic lens L to resume.

"3.0. In-_particuJier __ d_ans_c_e_mo_de..de_réaJisati-θn _I Ja. grinding .. of xetojjeche. MA comprises a ring 45 having an outer face constituting the edging face 99A. The ring 45 of the retouching wheel 31A is mounted on another ring in two parts 41, 42 whose inner face comprises grooves for cooperating with the fluted ball 40. The two parts of the ring are interconnected by two screws 43,44.

In order to axially stop the retouching wheel 31A with respect to the ball 40, the corrugated housing 70 of the retouching wheel 31A is narrowed at its ends to form shoulders 71, 72 for stopping the retouching wheel 31A. relative to the ball 40. The shoulders 71, 72 of the housing have a plurality of curved sections whose shapes match those of the curved sections of the ball 40 allowing the pivoting of the retouching wheel 31A around its pivot axes until at a certain pivot angle. In this embodiment, the retouching wheel 31A has a free angular displacement around its two pivoting directions. Accordingly, the angular reminder of the retouching wheel 31A in its return position is exclusively generated by the rotation of the retouching wheel around its axis of rotation A4, under the effect of its inertial centripetal force. For mounting considerations, there is disposed between the retouching grinding wheel 31A and the shaft 37 for rotating a spacer 51 to the right of the ball 40 in the drawing of Figure 7, to stop the various elements that could oppose the tilting of the retouching wheel 31A around its pivot axes. Indeed, after having arranged all the components of the tool 3OA working on the drive shaft 37, it is tighten all the various elements arranged on the work tool 30A with a screw 36 and a washer 23. This screw cooperates with a tapped hole arranged at the end of the shaft 37 of the working tool 30A. It is interesting to note that since the restoring force is solely due to the inertial force of rotation, it is preferable to have a retouching wheel 31A suitably balanced accordingly.

identiques ou similaires des différents modes de réalisation de l'invention sont référencés par les mêmes signes de référence. On retrouve ainsi la meule de rainage 35 montée sur le support 38 à la faveur de la rotule 40 et de la goupille d'arrêt en rotation 50, l'arbre d'entraînement en rotation 37, la vis 36 et sa rondelle 23.Figure 5 shows a second embodiment of a work tool 3OC. This embodiment is a variant of the previous embodiment. __ In one

identical or similar of the various embodiments of the invention are referenced by the same reference signs. We thus find the creasing wheel 35 mounted on the support 38 in favor of the ball 40 and the pin rotation stop 50, the rotational drive shaft 37, the screw 36 and its washer 23.

This tool 3OC comprises a retouching wheel 31 C made differently from the previous embodiment. For mounting considerations, there is provided between each seal 47,48 elastic and drive shaft 37 a spacer 55,56. The spacers 55,56 then serve as shoulder to the various elements distributed on either side of the retouching wheel 31 C on the tool 3OC.

The return means of the retouching wheel are elastic. More precisely, these return means comprise two axially and / or radially compressible elastic joints 47, 48 mounted on the axis of rotation A4.

The seals each have an edge bearing against the corresponding side of the retouching wheel 31 C and an opposite edge bearing against a stop associated with the spacers 55,56. The two seals 47.48 elastic are for example elastomer. The return force due to these elastic return means is then added to the restoring force due to the centripetal inertial force resulting from the rotation of the retouching wheel around its axis of rotation.

Here, unlike the first embodiment of Figure 4, the corrugated housing 75 of the retouching wheel 31 C has no parts closing around the ball 40. Indeed in the first embodiment the closed parts of the housing serve as shoulder for the axial stops of the grinding wheel relative to the patella. Here, the retouching wheel 31 C is stopped in axial translation by the seals 47,48.

The trimming device 10 and its working tool 30 (or one of its variants 30A; 30C) are advantageously used for carrying out a method of trimming the periphery of the ophthalmic lens L.

Prior to the first machining, the lens L is centered and locked according to a first centering reference by means of the two locking noses 62, 63. Optical measurements provide a theoretical reference for centering the ophthalmic lens L in the clamping shafts 12, 13. The inaccuracies of blocking the

compared to the clamping shafts 12,13 slightly different from the theoretical calculated by optical measurement. It is in this first real reference that the first machining is performed. The lens L is then cut off by machining by means of the main roughing and finishing grinding wheels of the grinding wheel set 14. the edge faces of these main grinding wheels are parallel to the axis A2 of rotation of the clamping shafts 12, 13 of the L lens.

In the example illustrated in FIG. 6, the lens L, which initially has an edge P1 of initially straight profile, is cut off by a grinding wheel 101 of axis A3 belonging to the set of wheels 14. This grinding wheel 101 has a face cylindrical abrasive edging 102 in recess which is formed a beveling groove 103 whose surface is also abrasive. The restitution mobility 10 RES of the shafts 12, 13 support of the lens is used for this work.

After the trimming, the edge of the lens has a bevel B2 and a bevel foot P2 as shown in FIG.

After this first machining, the lens L is unlocked and thus is disengaged from the locking faces of the clamping shafts 12, 13. It results from this release a loss of the first real centering repository.

In the case where the trimming of the lens L previously performed by means of the first machining is not in accordance with the desired result but leads to a singing locally or overall too large in radius the optician proceeds to a

20 retouch retouching the edge C of the lens L by means of a second machining.

This premium can be involuntary or voluntary.

It is involuntary when the optician has sought directly at the first trimming the desired radius dimension and inaccuracies or machining drifts 25 have resulted in a higher rating.

But the premium after the first machining can also be sought. We can indeed predict that the bevel B2 is deliberately machined to a radius of slightly greater than that ultimately desired, to avoid any risk of birth of a game in the interlocking of the bevel of the lens in the bezel

In view of the machining inaccuracies, it is sufficiently low to allow satisfactory assembly without play or excess of stresses or, on the contrary, being too high. In the latter case, a clipping editing according to the invention is necessary. Before the second retouching machining, the lens is again locked between the shafts 12, 13. This new locking of the lens can be performed approximately, at the estimate or at an arbitrary predefined position. Such an approximate blocking, authorized by the invention, saves time and resources, saving money and reducing cycle times.

It is also possible, although it is longer, to recalculate, by optical measurement or by an acquisition of the geometry of the periphery of the lens followed by a matching of shape with the desired geometry, the theoretical center of reference However, even in this second hypothesis, the inaccuracies of these optical measurements mean that the centering reference obtained in this second machining step may differ slightly from the first theoretical reference used during the first machining step. . In addition, in addition to these optical measurement inaccuracies, the locking inaccuracies of the lens L. Whatever, therefore, the mode of reblocking of the lens, the second centering reference obtained is therefore different from the first. This results in a positioning offset of the lens L relative to the grinding wheel during this second machining. In particular, the lens L being off-center with respect to its centering position of the first machining, the edge C of the lens L is inclined with respect to the edging face 99 (or one of its variants 99A; grinding wheel. Thus, the machining in this configuration could not allow without the implementation of the invention to obtain the desired radii of curvature at the edge of the lens.

Before retouching the ophthalmic lens L, the lens is probed at a point on one of its faces close to its periphery. This feeling of the lens L then makes it possible to position the groove of the grinding wheel vis-à-vis the bevel of the lens to be retouched in the vicinity of the point previously palpated, then to insert the bevel of the lens into the groove. The free translation mobility M2 and / or tilting mobility M1 then make it possible to obtain a natural follow-up of the trajectory of the bevel by the grinding wheel.

The second retouching machining is then performed with the retouching wheel 31 (or one of its variants 31A; 31C) of edging. The retouching wheel is approaching the edge C of the lens L to overflow thanks to the degree of retraction mobility ESC of the finishing module 25, in a plane transverse to the tightening shafts 12, 13 of the lens L. The transfer mobility TRA, which also affects the module 25, makes it possible to position the beveling groove 32 of the retouching wheel 31 facing the bevel B previously formed during the first machining of clipping. The grinding wheel 31 is then in the configuration of FIG.

The grinding wheel 31 is rotated about its axis A4 and is moved towards the lens L by means of ESC retraction mobility to be applied against the edge of the lens to be retouched, with a predetermined constant force.

The groove 32 of the grinding wheel 31 is shallower than the groove 103 of the grinding wheel 101. The difference in depth is, for example, approximately 0.025 mm.

The abrasive groove 32 thus makes the bevel B2 to reduce the radial dimension until the bearing surface 99 of the grinding wheel 31 reaches abutment against the bevel foot P2. From this abutment, the grinding wheel 31 slides on the edge of the lens without machining it. The electronic processing unit or the operator detects the end of the advance of the wheel and then stops machining.

The edge of the lens then has the configuration shown in Figure 9, with an unchanged bevel foot P2 and a bevel B3 radial dimension or, in other words, reduced height.

During this resumption of the edging, the free mobility of M2 translation and tilting M1 (Figure 3) of the retouching grinding wheel 31 (or one of its variants 31A, 31C) are used. By free tilting M1 in effect, when the bevel B2 of the lens L is brought into contact with the groove 32 (or one of its variants 32A, 32C) of the retouching wheel 31 (or one of its variants

31A, 31C), the grinding wheel 32 inclines itself to dynamically adapt to the local orientation of the bevel foot P2 of the edge of the lens L. In addition, the freedom of translation M2 of the support 38 and hence, the retouching wheel 31 can axially accompany the trajectory of the bevel of the lens. The retouching thus carries, as desired by the optician, exclusively on the radius values of the edge of the lens and in particular of its bevel. The shape of the song (bevel and foot of bevel) is preserved.

The tilting mobility of the retouching wheel 31 (or one of its variants 31A; 31C) is of spherical type, rigid radially. When a pressing force is exerted from the lens L on the retouching wheel, this radial rigidity allows the retouching wheel to not move radially relative to the support 38. A radial displacement of the grinding wheel relative to the support 38 would modify the machining dimension of the lens. Or ₁ the machining dimension must be respected as precisely as possible to obtain the desired radius at the C song considered that we take again.

During this second machining of the edge C of the lens L, the retouching wheel 31 (or one of its variants 31A; 31C) is recalled, in its pivoting about its pivoting directions, in its return position. so that the edging face 99 (or one of its variants 99A; 99C) of the retouching wheel is always parallel to the edge C of the lens L to overflow. This

The booster may result from the inertial force driving the retouching wheel in rotation. Thanks to this inertial force, the retouching wheel naturally tends to recover in a plane perpendicular to its axis of rotation A4 while following the song C of the lens by using its two degrees of freedom of tilting around the axis of rotation. A4 rotation.

This reminder of the retouching wheel 31 (or one of its variants 31A; 31C) in its return position can also be achieved by means of elastic means. In the latter case, the inertial force of rotation drive is added to the elastic restoring force.

In addition, chamfering face 33.98 (or one of its variants

33A, 98A; 33C, 98C) of the retouching wheel 31 (or one of its variants 31A; 31C) enables a step of chamfering the sharp edges E1, e2 of the edges of the lens L by means of said grinding wheel. The freedom of tilting M1 and the freedom of translation M2 of the retouching wheel 31 (or one of its variants 31A, 31C) optimize this step of finishing or resumption chamfering.

To make a correct chamfering it must be taken into account that the width of the chamfer is proportional to the machining force and thus to avoid variations in machining force. The rotational mounting of the retouching wheel 31 (or one of its variants 31A; 31C) makes it flexible. Now it is known that the flexibility of the grinding wheel helps absorb the contact pressure changes during this ^^^^ _ Q_ d ™ bâθl ^ -?!? 9®ϋ _{r 3.} Sigh of Ma jrieuje _{. allows.} therefore I exercise one _. regular support of the lens on the wheel and to have a regular chamfer width.

FIGS. 10 to 12 illustrate an alternative embodiment of the invention in which the trimming of a lens L is carried out in two stages. The lens L here has a pre-formed ring having a bevel B4 and a bevel foot P4 which both has an excess or overhang of radial dimension. It is then a question of reducing uniformly the radial dimension of the bevel and the foot of bevel of the song without modifying the shape. In particular, contrary to the embodiment previously described with reference to FIGS. 6 to 9, it is desired not to modify the height of the bevel or, otherwise formulated, not to modify the relative radial dimensions of the bevel and the bevel root.

In a first step, the edge of the lens L to be retouched is machined by a first grinding wheel 110. rotatably mounted on the axis A4. This first grinding wheel 110 has a cylindrical edging face 111 which is abrasive and at the recess of which is formed a bevelling groove 114. This groove 114 has on the one hand two abrasive flanks 112 having a V profile and on the other hand a bottom recess 113 and profile V which is smooth and hence non-abrasive. The bevel B4 of the lens and the bevel foot P4 are respectively machined by the flanks 112 of the groove 114 and the cylindrical flange face 111. Only the top of the bevel B4 is not affected by the machining and engages in the depression of the bottom 113 of the groove 114. The retraction advance ESC continues and the lens is machined and narrowed radially until the top of the bevel B4 reaches the abutment against the bottom 113 of the groove 114 which, being smooth, slides on the bevel top without machining it. The depth of pass is thus limited by the recess height or recess d of the bottom 113 of the groove 114.

At the end of this first operation, the edge of the lens has the configuration of FIG. 11, with a P5 bevel foot of smaller radii than the initial bevel foot P4 and with a B5 bevel whose B5.1 flanks. also have reduced radii compared to the initial bevel B4. Reducing foot ray bevel P5 and B5.1 flanks B5 bevel is uniform and equal to the recess or height of the recess bottom 113 of the groove 114 of the wheel 110. B5 bevel present _a i _^ top B5. ^ Elevated by height.

In a second step, the top B5.2 of the bevel B5 is leveled. For this purpose, using a second grinding wheel 120 rotatably mounted on the axis A4. This second grinding wheel 120 has a cylindrical flange face 121 which is abrasive and recess of which is formed a bevelling groove 124. This groove 124 has, on the one hand, two flanks 122 which are smooth and therefore non-abrasive, and which have a V-shaped profile and on the other hand , a bottom 123 which is in continuity with the flanks 122 and which is instead abrasive. The apex B5.2 of the bevel B5 of the lens is machined by the bottom 123 of the groove 124. The retraction advance ESC continues and the top B5.2 of the bevel B5 is machined and radially narrowed until the flanks B5.1 of the bevel B5 abut against the flanks 122 of the groove 124 which, being smooth, slide on the flanks B5.1 of the bevel B5 without machining it. The top B5.1 of the bevel B5 is thus reduced to reduced radius values of the height d, in continuity with the flanks B5.1 of the bevel.

The final configuration obtained is shown in Figure 12 where it can be seen that the edge of the lens has a foot P6 identical to the foot P5 obtained at the end of the first step and a bevel B6. This bevel foot P6 and the bevel P6 have radius values decreased by the height d accurate with respect to the bevel foot P4 and the bevel B4 of the initial predetched lens.

It is possible to repeat several times these two machining steps with a depth of pass d limited by the abutment of the lens against the smooth portions 113, 121, 122 of the wheels 110, 120 to achieve a reduction of values of rays of the singing of the lens of a predefined multiple of the depth of pass d. For example, if it is desired to effect a retouch at 0.05 mm radius, the two-step retouching process described above is carried out twice.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

The work tool comprising the retouching wheel can also be used for resuming the trimming of a lens on which a tassel is applied. Indeed, the grinding wheel editing retrieves the trimming of the l§θti] lejηιalgréjes dispersions glans repositioning _^ solidajre of] a lens on the clamping and drive shafts in rotation.

On the other hand, although in the previously described embodiments, the grinding wheels 31, 110, 120 have a bearing portion 99; 113; 121, 122 smooth without abrasive power, it is also possible to provide that said bearing portion has a some abrasive power lower than that of the machining portion 32; 111, 112; 123 with a roughness substantially lower than that of the machining portion so as to form the desired abutment element. The arrival in abutment of the lens against the support portion of the grinding wheel is then detected by means of detecting a strong slowdown in the speed of advance of the grinding wheel relative to the lens or an increase in the machining effort on ESC retraction mobility or its equivalent. It is also possible not to detect the abutment as such, but to provide a maintenance of the machining advance force of each retouching or finishing machining step during a predefined cycle time that is on the one hand, long enough for the lens to abut in all cases and, on the other hand, short enough not to degrade the part or parts of the edge of the lens which are abutted (if the stop element is not perfectly smooth, but slightly rough).

The bearing portion 99; 113; 121, 122 may in particular be roughness able to polish the lens, so as to perfectly preserve the aesthetics of the edge of the lens.

Claims

1. Process for finishing or retouching the periphery of an ophthalmic lens (L) according to a profiled edge (C), comprising at least one step of machining finishing or retouching of a part of the profile of the edge (C) the lens with a depth of pass limited by an abutment of another part of said profile against a stop element. 2. Method according to the preceding claim, wherein the edge to be made of the lens has a bevel. 3. Method according to the preceding claim, wherein said other portion which is abutted corresponds to at least a portion of the bevel. The method of claim 2, wherein said other abutting portion corresponds to at least a portion of the bevel root. 5. Method according to one of the preceding claims, wherein is repeated several times the machining step of finishing or retouching a portion of the profile of the edge (C) of the lens with a depth of pass limited by a abutting to achieve a reduction of radius values of the edge of the lens of a predefined multiple of the depth of pass. 6. Method according to one of the preceding claims, wherein the finishing machining or retouching being performed by means of a profiled tool (31; 31A; 31C) which is rotatably mounted about an axis of rotation ( A4) and having a machining portion (32; 111; 112; 123) and a bearing portion (99; 113; 121,122), said bearing portion having a roughness substantially less than that of the said machining part so as to form said abutment element. 7. Method according to the preceding claim, wherein the bearing portion (99; 113; 121, 122) is smooth without abrasiveness or roughness able to polish the lens. 8. Method according to one of the preceding claims, wherein the finishing machining or retouching is performed by means of a tool (31; 31A; 31C) which is rotatably mounted about an axis of rotation (A4). and which has at ^{~ "Tϋsinagë} ϋèlmifiôή δCTclë editing ¥ ^{u" ~} moins7bϋtrê sâΥotatiôrr around dϋdifâxë ^"" rotation (A4), a mobility free translation (M2) having at least one component parallel to its axis of rotation (A4) 9. Method according to one of the preceding claims, wherein the finishing machining or retouching is performed by means of a tool (31; 31A; 31C) which is rotatably mounted about an axis of rotation (A4). and which possesses during the finishing machining or retouching at least, in addition to its rotation about said axis of rotation (A4), a tilting mobility (M1) with two degrees of freedom around two distinct pivotal directions substantially transverse to its axis of rotation (A4). 10. Method according to the preceding claim, wherein the tool (31; 31A; 31C) is recalled, in its pivoting about its pivoting directions, in a return position. 11. Method according to one of the preceding claims, applied to a retouch of the trimming of the edge (C) of the lens (L) after prior trimming. 12. Method according to the preceding claim, characterized in that it comprises the following preliminary steps: - before the preliminary machining, the lens (L) is centered and blocked according to a first centering reference, after the preliminary machining, the lens (L) is released with loss of the centering reference, - before finishing or retouching machining, the lens (L) is locked again. 13. Method according to the preceding claim, wherein, before finishing machining or retouching, the lens (L) is locked again without being centered by reacquisition of a centering reference. 14. Method according to one of the preceding claims, comprising: a first step of finishing machining or retouching of a first part of the profile of the edge of the lens with a depth of pass limited by an abutment of a second part of said profile against a stop element, a second step of machining finishing or retouching of the second portion of the profile of the edge of the lens with a depth of pass limited by abutting already the first part of said profile against urjment. 15. Method according to the preceding claim, wherein the first portion and the second portion of the edge profile of the lens are complementary to form the whole of said profile.