EP0744246A1 - Positioning gauge for setting-up an ophthalimic lens grinding machine and corresponding setting-up method - Google Patents

Abstract

The template is mounted in the place of the ophthalmic lens on the grinder to be calibrated. It has the general shape of a disc being circular on a part of its periphery (22). There are locally two sharp points (23), circumscribed by the same circumference (C), which are angularly separated from each other by 90 degrees . In the smallest (A'1) of the two subtended angles at the centre (A'1,A'2) delimited by the sharp points the disc contour is concave. The circumference which circumscribes the two sharp points on its periphery then extends into its circular part (22A). The two sharp points result from the intersection of the disc circular part with a notch (22B) cut into its periphery.

Description

The present invention relates generally to the calibration to which it is necessary to start up an ophthalmic lens grinder 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 a grinding wheel.

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

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

According to the invention, and according to methods which will be described in more detail later, it takes advantage of these angular points, to determine the angular position of the axis of rotation of an ophthalmic lens in the rotation frame of the together, and thus be able to effectively mount this ophthalmic lens along the axis to be observed.

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

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

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

During calibration, advantage is taken of this smooth and cylindrical portion of the periphery of the calibration template according to the invention in order to know the overall diameter of a grinding wheel when it is a roughing grinding wheel or of a finishing wheel in ice mode, and thus be able later to satisfy the overcalibration value to be respected for the corresponding blank, however, by doing the same with the portion of this periphery forming a bevel, it is also possible to meet the dimensions to be observed for the finished ophthalmic lens.

The calibration template according to the invention is finally further characterized in that it comprises two hollow bosses, which, angularly offset from one another, each protrude respectively on its two faces while being in continuity l '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 the two hollow bosses, extends from one to the other of these.

When, in accordance with the provisions of the French patent which, filed under No 83 04637, on March 22, 1983, was published under No 2 543 039, the grinder comprises at least one probe which, by application to the one and / or the other of the faces of the ophthalmic lens, allows a statement of trajectories to the right of the end of the bevel to be assured, it is taken advantage, during calibration, of the hollow bosses of the calibration template according to invention to check the position of the probe (s) thus present on the grinder, and thus be able to subsequently determine suitably the position to be observed for the ophthalmic lens.

These hollow bosses also advantageously make it possible to check the linearity of this or these feelers.

• 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 lens grinder ophthalmic to which the invention may apply;
• 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 diagrammatically in FIG. 1, and in a manner known per se, the grinder 10 according to the invention comprises, on the whole, on the one hand, a rocker 11, which is mounted to pivot freely around a first axis A1, in practice a horizontal axis, on a frame not shown, and which, for supporting and maintaining an ophthalmic lens 12 to be machined, is equipped with two support pins 13 aligned with each other along a second parallel axis A2 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 locked in rotation on a third axis A3 parallel to the first axis A1, and which is also duly driven in rotation by a motor not shown.

For simplicity, the axes A1, A2 and A3 have only been shown diagrammatically in broken lines in FIG. 1.

In practice, several grinding wheels 14 are provided in parallel on the third axis A3, for roughing and 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 it is in practice a finishing grinding wheel having a groove 15 for machining a bevel on the ophthalmic lens 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 rocker 11 to l 'one of its ends, is articulated, at the other of its ends, along a fourth axis A4 parallel to the first axis A1, to a nut 17 mounted movably along a fifth axis A5, commonly called return axis, 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 diagrammatically in FIG. 1, the nut 17 is a threaded nut in screw connection with a threaded rod 38 which, aligned along the fifth axis A5, is driven in rotation by a motor 19.

For example, also, the contact sensor 18 is constituted by a Hall effect cell.

When, duly sandwiched between the two support pins 13, the ophthalmic lens 12 to be machined is brought into contact with the grinding wheel 14, it is the object of an effective removal of material until the rocker 11 comes to abut against the link 16 following a support which, being made at the level of the contact sensor 18, is duly detected by the latter.

For the machining of the ophthalmic lens 12 along a given contour, it suffices, therefore, on the one hand, to move the nut 17 accordingly along the fifth axis A5, under the control of the motor 19, and, on the other hand hand, to jointly rotate 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 are successively concerned.

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

The foregoing provisions are moreover well known in themselves, and, not belonging specifically to the present invention, they will not be described in more detail here.

It goes without saying that, for a good execution of this double operation, it is advisable that the various axes in question are well identified with respect to each other.

More specifically, the first axis A1 and the third axis A3 being fixed axes on the frame of the assembly, it is appropriate that, in the reference frame of rotation of the assembly, the angular position of the second axis A2 relative to the third axis A3, defined by the angle T that the flip-flop 11 makes with respect to the plane containing the first axis A1 and the third axis A3, can be duly identified.

Likewise, the position of the nut 17 along the fourth axis A4, shown schematically by a double arrow R in FIG. 1, should be likened to a radius in the polar coordinates which it constitutes with the angle T, can be duly identified.

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

It is the same, of course, with the very diameter of this grinding wheel 14, whether it is 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 up, and it is necessary to periodically renew this calibration, in particular at each change or brightening of the grinding wheel 14.

The purpose of the calibration template 20 shown in FIGS. 3 to 8 is in particular to facilitate this calibration.

This calibration template 20, which is intended to be mounted on the grinder 10 to be calibrated, instead of an ophthalmic lens 12, is in the general form of a disc, of general thickness E, with, in protruding in its central zone, a hollow boss 21 suitable for enabling it to be mounted 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 it forms, locally, two angular points 23, which, circumscribed by the same circumference C, are angularly separated from one the other.

Relative 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 angles at the center, and A'2 the most developed.

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

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

In practice, in this embodiment, the two angular points 23 generally result from the intersection of this circular part 22A with a notch 22B cutting 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 comprises, overall, two parts, namely, a circular part 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 at the lowest angle at the center A'1.

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

In the embodiment shown, the two angular points 23 of the contour 22 are spaced from each other by 90 °.

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

On a portion 24 ', 24 ", at least, of the circular part 22A of its contour 22, the periphery of the calibration template 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 bevel 25 ', 25 "on two portions 24', 24" distinct, at least, from the circular part 22A of its outline. 22, and the corresponding bevels 25 ', 25 "are different.

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

In the embodiment shown, the two corresponding portions 24 ′, 24 ″ of the periphery of the calibration template 20 are adjacent, and, disposed generally at a distance from each of the angular points 23, they are each extend at an angle at the center substantially equal to 60 °.

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

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

In practice, in the embodiment shown, two smooth and cylindrical portions 26 ′, 26 ″ are provided, each counting from the two angular points 23.

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

The calibration template 20 according to the invention further comprises two hollow bosses 27A, 27B, which, angularly offset from one another, each project respectively 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 hollow bosses 27A, 27B extend generally circularly, at a distance from the circular part 22A of the contour 22, in the most developed angle at the center A'2.

Measured from the radial end wall of one to the end wall of the other, the central angle which underpins them overall is of the order of 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 lugs 32A, 32B are in line with 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, a certain number of operations are carried out, which, preferably, are carried out in the following order.

First of all, after the setting up of this calibration jig 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 jig 20 comes to bear on the grinding wheel 14 by one of its angular points 23, as shown in FIG. 9A.

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

There is then an incrementation of the angular position of the calibration template 20 around the second axis A2, until it comes to bear by its other angular point 23 on the grinding wheel 14, as shown in FIG. 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 the operations are repeated until the value of the corresponding reading R is minimum.

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

The angular value corresponding to the minimum reading R obtained is stored, and it is this which will be used as a reference for the establishment of the restitution set point tables to be observed for the second axis A2 during the machining of an ophthalmic lens 12.

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

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

The calibration jig 20 is then in the position shown in FIG. 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 position Z of the grinding wheel 14 on the third axis A3 is then stored, and it is this which will be taken into account for the establishment of the return deposit tables.

By these operations, the diameter of the grinding wheel 14 at the bottom of its groove 15 is also determined, if, as in the present case, it is a finishing grinding wheel, and, by analogous operations then involving a portion 26 ', 26 "smooth and cylindrical of the calibration template 20, the overall diameter of this grinding wheel 14 is determined, if it is a roughing grinding wheel.

In both cases, the corresponding value is stored, and it is this which will be used for the establishment of the return deposit tables.

Finally, when, as described in French patent No 83 04637 mentioned above, the grinder 10 comprises at least one probe 35, and, for example, two probes 35, as shown, a linearity check is carried out of these, after the pins 32A, 32B have enabled visually check the position.

To do this, the probes 35 are first brought to the rear stop, so that the origin of their respective local references is well defined.

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

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

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

These parameters must be close to the corresponding theoretical values.

Otherwise, the probes would not be in conformity.

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

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

Of course, also, the present invention is not limited to the embodiment described and shown, but encompasses any variant of execution and / or implementation, in particular as regards the order of the operations to be carried out during the implementation of the calibration template according to the invention.

Claims (17)

Calibration template for calibrating an ophthalmic lens grinder, characterized in that, intended to be mounted in place of an ophthalmic lens (12) on the grinder (10) to be calibrated, it is provided under the general shape of a disc, and in that, circular on at least part of its perimeter, its outline (22) locally forms two angular points (23) which, circumscribed by the same circumference (C), are angularly separated from each other. Calibration template according to claim 1, characterized in that, in the lower (A'1) of the two central angles (A'1, A'2) delimited by the angular points (23), its outline (22) is generally concave. Calibration template according to any one of claims 1, 2, characterized in that the circumference (C) which circumscribes the two angular points (23) of its outline (22) is that along which the circular part (22A) extends ) of it. Calibration template according to claim 3, characterized in that the two angular points (23) of its outline (22) result from the intersection of the circular part (22A) of the latter with a notch (22B) cutting into its periphery . Calibration template according to any one of claims 1 to 4, characterized in that the two angular points (23) of its outline (22) are spaced from each other by 90 °. Calibration template according to any one of Claims 1 to 5, characterized in that, on at least one portion (24 ', 24 ") of the circular part (22A) of its outline (22), its periphery forms a bevel (25 ', 25 "). Calibration template according to claim 6, characterized in that its periphery forms a bevel (25 ', 25 ") on two portions (24', 24") distinct, at least, from the circular part (22A) of its outline ( 22), and the corresponding bevels (25 ', 25 ") are different. Calibration template according to any one of Claims 1 to 7, characterized in that, on at least one portion (26 ', 26 ") of the circular part (22A) of its contour (22), its periphery is smooth and cylindrical. Calibration template according to any one of Claims 1 to 8, characterized in that it comprises two hollow bosses (27A, 27B), which, angularly offset from one another, each protrude respectively 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. Calibration template according to claim 9, characterized in that the connecting wall (31) common to the two hollow bosses (27A, 27B) extends generally at an angle relative to its faces (28A, 28B). Calibration template according to any one of claims 9, 10, characterized in that the connecting wall (31) common to the two hollow bosses (27A, 27B) is planar. Calibration template according to any one of Claims 9 to 11, characterized in that the bottom (29) of the two hollow bosses (27A, 27B) is flat. Calibration template according to claim 12, characterized in that the bottom (29) of the two hollow bosses (27A, 27B) extends parallel to its faces (28A, 28B). Calibration template according to any one of Claims 9 to 13, characterized in that the two hollow bosses (27A, 27B) extend generally circularly. Calibration template according to any one of claims 1 to 14, characterized in that it has a lug (32A, 32B) projecting on each of its faces (28A, 28B). Calibration template according to claim 14, characterized in that, from one of its faces (28A, 28B) to the other, the pins (32A, 32B) are in line with each other. Method for calibrating a grinder (10) for ophthalmic lens (12), characterized in that it involves the use of a calibration template (20) according to any one of claims 1 to 16 .

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