EP0744246B1 - Positioning gauge for setting-up an ophthalimic lens grinding machine and corresponding setting-up method - Google Patents

Description

The present invention relates generally the calibration to be performed when starting up a ophthalmic lens grinder of the type described in FR-A-2 543 039 to have a precise reference for its various parameters, it being understood that this calibration can then be periodically renewed, especially when changing or brightening up a grinding wheel.

More specifically, it relates to a template of calibration specific to such a calibration and the calibration process involving the implementation of such a calibration template.

The calibration template according to the invention is of generally characterized in that, intended to be mounted instead of an ophthalmic lens on the grinder calibrate, it comes in the general form of a disc, and in that, circular over at least part of its perimeter, its outline locally forms two points angular, which, circumscribed by the same circumference, are angularly spaced from each other.

According to the invention, and according to methods which will be described in more detail later, it is drawn from these angular points, to determine the position angle of the axis of rotation of an ophthalmic lens in the rotation reference of the assembly, and thus power actually mount this ophthalmic lens along the axis to respect.

The calibration template according to the invention is still characterized in that, on at least a portion of the portion circular in outline, its periphery forms a bevel.

During calibration, it takes advantage of this bevel to know the position of the groove of the grinding wheel when is a finishing wheel, and thus be able to place later correctly on the edge of the ophthalmic lens the bevel to be formed thereon.

The calibration template according to the invention is still characterized in that, on at least a portion of the portion circular in outline, its periphery is smooth and cylindrical.

This calibration takes advantage of this portion smooth and cylindrical around the periphery of the calibration template according to the invention to know the overall diameter of a grinding wheel in the case of a roughing wheel or a grinding wheel finishing in ice mode, and thus power later satisfy the overcalibration value to be respected for the corresponding draft, however, that by doing the same with the portion of this periphery forming a bevel, it is also possible to satisfy the ratings to be respected for the finished ophthalmic lens.

Finally, the calibration template according to the invention is further characterized in that it comprises two hollow bosses, which, angularly offset from each other, make each protruding respectively on its two faces while being in continuity with each other, the bottom of each of these hollow bosses connecting continuously with the top of the other by a connecting wall, which, common to both hollow bosses, extends from one to the other of these.

When, in accordance with the provisions of French patent which, filed under No 83 04637, on March 22 1983, was published under No. 2,543,039, the grinder has at least one probe which, by application to one and / or the other of the faces of the ophthalmic lens, allows a reading of trajectories to the right of the end of the bevel to ensure, it takes advantage, during calibration, of the hollow bosses of the template according to the invention to check the position of the or probes thus present on the grinder, and power so later properly determine the position to be observed for the ophthalmic lens.

These hollow bosses also advantageously allow to check the linearity of this or these probes.

la figure 1 est, avec un arrachement local, une vue schématique, en perspective, d'une meuleuse pour lentille ophtalmique à laquelle est susceptible de s'appliquer l'invention ;

la figure 2 reprend, à échelle supérieure, le détail de la figure 1 repéré par un encart II sur cette figure 1 ;

la figure 3 est, à échelle supérieure, une vue en élévation, de face, du gabarit de calibrage mis en oeuvre suivant l'invention pour l'étalonnage de cette meuleuse ;

la figure 4 est une vue de dessus, suivant la flèche IV de la figure 3, de ce gabarit de calibrage ;

la figure 5 en est une vue en coupe axiale, suivant la ligne brisée V-V de la figure 3 ;

la figure 6 en est, supposée développée à plat, une vue partielle en coupe circonférentielle, suivant la ligne VI-VI de la figure 3 ;

les figures 7 et 8 en sont, à échelle supérieure, des vues partielles en coupe axiale, suivant, chacune respectivement, les lignes VII-VII et VIII-VIII de la figure 3 ;

les figures 9A, 9B, 9C sont des vues schématiques en élévation, qui, dérivées de celle de la figure 3, illustrent diverses phases de mise en oeuvre du gabarit de calibrage suivant l'invention ;

les figures 10A et 10B sont des vues de côté se rapportant à d'autres phases de cette mise en oeuvre ;

la figure 11 est une vue en coupe circonférentielle qui, dérivée de celle de la figure 6, se rapporte également à une autre phase de cette mise en oeuvre.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which:

Figure 1 is, with a local cutaway, a schematic perspective view of a grinder for ophthalmic lens to which is likely to apply the invention;

Figure 2 shows, on a larger scale, the detail of Figure 1 identified by an insert II in this Figure 1;

Figure 3 is, on a larger scale, an elevational front view of the calibration jig used according to the invention for the calibration of this grinder;

Figure 4 is a top view, along arrow IV of Figure 3, of this calibration template;

Figure 5 is an axial sectional view along the broken line VV of Figure 3;

Figure 6 is, assumed to be developed flat, a partial view in circumferential section, along line VI-VI of Figure 3;

Figures 7 and 8 are, on a larger scale, partial views in axial section, along, each respectively, the lines VII-VII and VIII-VIII of Figure 3;

Figures 9A, 9B, 9C are schematic elevational views, which, derived from that of Figure 3, illustrate various phases of implementation of the calibration template according to the invention;

FIGS. 10A and 10B are side views relating to other phases of this implementation;

Figure 11 is a circumferential sectional view which, derived from that of Figure 6, also relates to another phase of this implementation.

As shown schematically in Figure 1, and so known per se, the grinder 10 according to the invention comprises, overall, on the one hand, a scale 11, which is mounted freely pivoting around a first axis A1, in practice a horizontal axis, on a chassis not shown, and which, for the support and maintenance of an ophthalmic lens 12 to be machined, is equipped with two support pins 13 aligned one with the other along a second axis A2 parallel to the first axis A1 and duly driven in rotation by a motor also not shown, and, on the other hand, at least one grinding wheel 14, which is stalled in rotation on a third axis A3 parallel to the first axis A1, and which is also duly rotated by an engine not shown.

For simplicity, axes A1, A2 and A3 have were only shown schematically in broken lines in Figure 1.

In practice, several grinding wheels 14 are provided in parallel on the third axis A3, for a roughing and a finishing of the ophthalmic lens 12 to be machined, and the assembly is carried by a carriage, also not shown, mounted movable parallel to the first axis A1.

In FIG. 1, only a grinding wheel 14 has been provided, and in practice it is a finishing wheel having a groove 15 for machining a bevel on the lens ophthalmic 12.

Being, in practice, an automatic grinder, commonly known as digital, the grinder 10 according to the invention further comprises a link 16, which, articulated to the chassis around the same first axis A1 as the flip-flop 11 at one of its ends, is articulated, at the other of its ends, following a fourth axis A4 parallel to the first axis A1, with a nut 17 movable climb along a fifth axis A5, commonly known as the axis restitution, perpendicular to the first axis A1, with, intervening between this link 16 and the rocker 11, a contact sensor 18.

For example, and as shown schematically in Figure 1, the nut 17 is a tapped nut in screwed engagement with a rod threaded 38 which, aligned along the fifth axis A5, is driven in rotation by a motor 19.

For example, also, the contact sensor 18 is consisting of a Hall effect cell.

When, duly clamped between the two pins of support 13, the ophthalmic lens 12 to be machined is brought to the contact with grinding wheel 14, it is being removed number of materials until flip-flop 11 abuts against the link 16 following a support which, being level of the contact sensor 18, is duly detected by this one.

For machining the following ophthalmic lens 12 a given contour, it is enough, therefore, on the one hand, to move in consequently the nut 17 along the fifth axis A5, under the motor control 19, and, on the other hand, to rotate together the support pins 13 around the second axis A2, in practice under the control of the motor which controls them, so that all the points of the contour of the ophthalmic lens 12 were successively concerned.

In practice, a control unit, duly programmed for this purpose, and not shown, coordinates this double surgery.

The foregoing provisions are moreover well known by themselves, and, not falling under their own present invention, they will not be described in more detail here.

It goes without saying that, for a good execution of this double operation, the different axes involved are well identified with each other.

More precisely, the first axis A1 and the third axis A3 being fixed axes on the chassis of the assembly, it agrees that, in the overall rotation frame, the angular position of the second axis A2 relative to the third axis A3, defined by the angle T made by the flip-flop 11 by relation to the plane containing the first axis A1 and the third axis A3, can be duly identified.

Similarly, the position of the nut 17 along the fourth axis A4, shown schematically by a double arrow R in Figure 1, because it can be assimilated to a radius in the polar coordinates that it constitutes with the angle T, can be duly identified.

Finally, the position of the grinding wheel 14 along the third axis A3, shown schematically by a double arrow Z in FIG. 1, because it can be assimilated to an "altitude", itself can be duly identified.

The same is true, of course, of the diameter itself of this grinding wheel 14, whether its overall diameter or whether it is its diameter at the bottom of its groove 15.

For these various locations, it is necessary to calibrate the grinder 10 when it is started, and it is necessary to periodically renew this calibration, in particular at each change or brightening of the grinding wheel 14.

The calibration template 20 shown in the figures 3 to 8 in particular aims to facilitate this calibration.

This calibration template 20, which is intended to be mounted on the grinder 10 to be calibrated, instead of a ophthalmic lens 12, comes in the general form of a disc, of general thickness E, with, projecting in its central zone, a hollow boss 21 suitable for allowing its mounting on the support pins 13 of this grinder 10.

The outline 22 of this calibration template 20 is circular over at least part of its perimeter, specified later, but locally forms two points angular 23, which, circumscribed by the same circumference C, are angularly separated from each other.

With respect to the center O of the calibration template 20, these angular points 23 delimit two angles at the center.

Let A'1 be the weakest of these two central angles, and A'2 the most developed.

In practice, the outline 22 of the calibration template 20 is generally concave in the angle at the center A'1 the most low.

In the embodiment shown, the circumference C which circumscribes the two angular points 23 is the one along which the circular part 22A of the outline 22.

In practice, in this embodiment, the two angular points 23 generally result from the intersection of this circular part 22A with a notch 22B notching the periphery of the calibration template 20.

In other words, in this embodiment, the contour 22 of the calibration template 20 according to the invention has, overall, two parts, namely, a part circular 22A, which extends at the angle at the center A'2 the more developed, and a concave part which is formed by the notch 22B notching its periphery, and which extends along the lowest center angle A'1.

The notch 22B itself has in practice a profile globally circular.

In the embodiment shown, the two angular points 23 of the contour 22 are separated one of the other 90 °.

In other words, the angle at the center A'1 which underlies them is equal to 90 °.

On a 24 'portion, at least 24' 'of the portion circular 22A of its outline 22, the periphery of the template calibration 20 according to the invention forms a bevel 25 ', 25' '.

In practice, in the embodiment shown, the periphery of the calibration template 20 according to the invention forms a 25 ', 25' 'bevel on two separate 24', 24 '' portions, at least, of the circular part 22A of its contour 22, and the 25 ', 25' 'corresponding bevels are different.

For example, the dihedral D 'formed by the bevel 25' is equal to 90 °, figure 7, while that D '' that forms the bevel 25 '' is equal to 120 °, figure 8.

In the embodiment shown, the two corresponding 24 ', 24' 'portions of the periphery of the template 20 are adjacent, and, generally arranged at distance from one and from the other of the angular points 23, they each extend at an angle to the center substantially equal to 60 °.

In addition, in this embodiment, the bevels 25 ', 25' 'each have their edges truncated by a flat cylindrical.

On a 26 'portion, at least 26' 'of the portion circular 22A of its outline 22, the periphery of the template calibration 20 according to the invention is smooth and cylindrical.

In practice, in the embodiment shown, two smooth, cylindrical 26 ', 26' 'portions are provided, count, each respectively, of the two angular points 23.

One of them, the portion 26 ', extends along a angle at the center substantially equal to 60 °, while the other, the portion 26 '', extends at a substantially central angle equal to 90 °.

The calibration template 20 according to the invention also comprises two hollow bosses 27A, 27B, which angularly offset from each other, each make respectively protruding on its two faces 28A, 28B while being in continuity with each other, the bottom 29 of each of these hollow bosses 27A, 27B connecting continuously with the top 30 of the other by a connecting wall 31, which, common to the two hollow bosses 27A, 27B, extends from one to the other of these, crossing right through the general thickness E even of the calibration template 20.

In practice, in the embodiment shown, the connecting wall 31 extends generally at an angle with respect to the faces 28A, 28B, making for example with each of these an angle of the order of 45 °, and it is a flat wall whose thickness e , which is that of all the walls of the hollow bosses 27A, 27B, is much less than the general thickness E of the calibration template 20.

In the embodiment shown, the bosses hollows 27A, 27B extend generally circularly, to distance from the circular part 22A of the contour 22, in the most developed center angle A'2.

Measured from the radial end wall of one to the end wall of the other, the angle at the center which overall underpins is around 90 °.

In practice, the bottom 29 of these hollow bosses 27A, 27B is flat, and it extends substantially parallel to the faces 28A, 28B of the calibration template 20.

As for the other walls of these hollow bosses 27A, 27B, they extend substantially perpendicular to these faces 28A, 28B.

Finally, in the embodiment shown, the calibration template 20 according to the invention has a lug 32A, 32B projecting from each of its faces 28A, 28B.

In practice, from one of these faces 28A, 28B to the other, these pins 32A, 32B are at the right of each other.

In the embodiment shown, they are generally perpendicular to the faces 28A, 28B, and their end 33 is slightly blunt.

For the implementation of the calibration template 20 according to the invention, there are a number of of operations, which, preferably, are executed in the following order.

First of all, after the implementation of this template calibration 20 on the support pins 13 of the rocker 11, this rocker 11 is lowered, under the control of the nut 17, until the calibration template 20 comes to bear on the grinding wheel 14 by one of its angular points 23, such as shown in Figure 9A.

The corresponding contact is detected by the contact 18, as soon as continuing its movement under the nut 17, the link 16 moves away from the toggle 11.

There is then an incrementation of the angular position of the calibration template 20 around the second axis A2, until it comes to carry by its other angular point 23 on the grinding wheel 14, as shown in the Figure 9B.

As before, the contact sensor 18 detects the corresponding contact.

Each time, the position of the nut 17 on the fifth axis A5 is raised, and operations are repeated until the value of the corresponding R statement is minimal.

The calibration template 20 then rests on the grinding wheel 14 by its two angular points 23, as shown in Figure 9C.

The angular value corresponding to the minimum reading R obtained is put in memory, and it will be used as a reference for establishing deposit tables for the second axis A2 to be respected during the machining of an ophthalmic lens 12.

Following operations of the same type, the template calibration 20 is then applied to the grinding wheel 14 by that of its bevels 25 ', 25 "which corresponds to the groove 15 of this one.

In practice, it is initially placed away from this groove 15, as shown in FIG. 10A, then, after it has been raised slightly so as not to rub on this wheel 14, we move this wheel 14 slightly along of the second axis A2, the gauge is again brought into contact with it of calibration 20, each time the positions are identified of the second and third axes A2, A3, and we reiterate operations until the value of the distance between these is minimal.

The calibration template 20 is then in the position shown in Figure 10B, for which it is engaged by its bevel 25 ', or 25' ', in the groove 15 of the grinding wheel 14.

The value of the Z position of the grinding wheel 14 on the third axis A3 is then stored, and it is she who will be taken into account for the establishment of the return instructions.

These operations also determine the diameter of the grinding wheel 14 at the bottom of its groove 15, if, as in the present case, it is a finishing wheel, and, by operations analogues then bringing into play a portion 26 ', 26' 'smooth and cylindrical of the calibration template 20, the overall diameter of this grinding wheel 14, if it is a grinding wheel roughing.

In both cases, the corresponding value is memory, and it will be used for establishment of refund deposit tables.

Finally, when, as described in the French patent No 83 04637 mentioned above, the grinder 10 has at minus one probe 35, and, for example, two probes 35, as shown, the linearity of these, after the pins 32A, 32B have allowed visually check the position.

To do this, the feelers 35 are first brought into back gauge, so that the origin of their local benchmarks are well defined.

They are then moved so as to come by example wear, one on the bottom 29 of the hollow boss 27A, the other on the top 30 of this same hollow boss 27A, such as shown in solid lines in Figure 11, and their respective movements are duly noted.

The calibration template 20 is then pivoted around the second axis A2, so that, as shown schematically in broken lines in FIG. 11, the probes 35 arrive in contact with the bottom 29 and the top 30 of the hollow boss 27B.

The new movements noted allow, with the previous, to solve the equations with two unknowns determining the parameters of the linearity relationship of feelers 35.

These parameters must be close to the values corresponding theoretical.

Otherwise, the probes would not be in conformity.

If the probes are compliant, the The values read are, as before, stored in memory.

Of course, the various previous operations can be done automatically, during a cycle calibration, under the control of the control unit, duly programmed for this purpose, from the grinder 10.

Of course, also, the present invention is not not limited to the embodiment described and shown, but includes any variant of execution and / or implementation work, in particular with regard to the order of operations to during the implementation of the calibration template according to the invention.

Claims (17)

1. A gauging template for the calibration of a grinder for an ophthalmic lens, characterised in that, intended to be mounted in place of an ophthalmic lens (12) on the grinder (10) to be calibrated, it is in the general form of a disc and that, being circular over a part at least of its perimeter, its contour (22) locally forms two angular points (23) which, circumscribed by the same circumference (C), are angularly spaced from each other.
2. A gauging template according to claim 1 characterised in that, in the smaller (A' 1) of the two angles (A'1, A'2) at the centre, which are delimited by the angular points (23), its contour (22) is overall concave.
3. A gauging template according to either one of claims 1 and 2 characterised in that the circumference (C) which circumscribes the two angular points (23) of its contour (22) is that along which the circular part (22A) thereof extends.
4. A gauging template according to claim 3 characterised in that the two angular points (23) of its contour (22) result from the intersection of the circular part (22A) thereof with a recess (22B) which cuts away its periphery.
5. A gauging template according to any one of claims 1 to 4 characterised in that the two angular points (23) of its contour (22) are spaced at 90° from each other.
6. A gauging template according to any one of claims 1 to 5 characterised in that over a portion (24', 24'') at least of the circular part (22A) of its contour (22) its periphery forms a bevel (25', 25'').
7. A gauging template according to claim 6 characterised in that its periphery forms a bevel (25', 25'') over two separate portions (24', 24'') at least of the circular part (22A) of its contour (22) and the corresponding bevels (25', 25'') are different.
8. A gauging template according to any one of claims 1 to 7 characterised in that over a portion (26', 26'') at least of the circular part (22A) of its contour (22) its periphery is smooth and cylindrical.
9. A gauging template according to any one of claims 1 to 8 characterised in that it comprises two hollow bosses (27A, 27B) which, being angularly displaced with respect to each other, each respectively project from its two faces (28A, 28B), while being in a condition of continuity with each other, the bottom (29) of each of said hollow bosses (27A, 27B) being continuously connected to the top (30) of the other by a connecting wall (23) which, being common to the two hollow bosses (27A, 27B), extends from one thereof to the other.
10. A gauging template according to claim 9 characterised in that the connecting wall (31) which is common to the two hollow bosses (27A, 27B) extends generally inclinedly with respect to its faces (28A, 28B).
11. A gauging template according to either one of claims 9 and 10 characterised in that the connecting wall (31) which is common to the two hollow bosses (27A, 27B) is planar.
12. A gauging template according to any one of claims 9 to 11 characterised in that the bottom (29) of the two hollow bosses (27A, 27B) is flat.
13. A gauging template according to claim 12 characterised in that the bottom (29) of the two hollow bosses (27A, 27B) extends parallel to its faces (28A, 28B).
14. A gauging template according to any one of claims 9 to 13 characterised in that the two hollow bosses (27A, 27B) extend generally circularly.
15. A gauging template according to any one of claims 1 to 14 characterised in that it has a lug (32A, 32B) in projecting relationship on each of its faces (28A, 28B).
16. A gauging template according to claim 14 characterised in that the lugs (32A, 32B) are in line with each other from one of its faces (28A, 28B) to the other.
17. A process for the calibration of a grinder (10) for an ophthalmic lens (12) characterised in that it involves the use of a gauging template (20) according to any one of claims 1 to 16.

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