EP2509744B1 - Optical-grade surfacing tool - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to optical quality surfacing for surfaces such as a face of an ophthalmic lens or a camera lens or an instrument for observing distant objects or a face a semiconductor substrate.

Surfacing means any operation to modify the state of a previously shaped surface. These include polishing, grinding or etching operations to modify (decrease or increase) the roughness of the surface and / or to reduce the undulation.

BACKGROUND

We already know, especially by the French patent application 2,834,662 to which corresponds the US patent application 2005/0101235 , by the French patent application 2,857,610 to which corresponds the US patent application 2006/0154581 and by the French patent application 2,900,356 to which corresponds the US patent application 2008/0171502 , a tool for surfacing an optical surface, comprising: a rigid support having a transverse end surface; an elastically compressible interface secured to the rigid support, comprising a so-called central portion which is in line with said end surface of the rigid support and a so-called peripheral portion which is transversely beyond said end surface of the rigid support; a flexible pad adapted to be applied against a surface to be worked, subjected to the interface opposite the rigid support, comprising a so-called central portion which is located at the right of said end surface of the rigid support and a so-called peripheral portion which is transversely beyond said end surface of the rigid support; as well as elastic return means arranged between said rigid support and the peripheral portion of said interface, the combination of said peripheral portion of the buffer, said peripheral portion of the interface and resilient return means forming a stabilizing means of the tool during surfacing, said tool being adapted to perform a surfacing essentially at said central portion of the buffer.

In order to reduce the roughness of the optical surface, the tool is brought into contact with the latter while maintaining sufficient tool pressure on it so that, by deformation of the interface, the pad conforms to the shape of the optical surface. .

While watering the optical surface with a fluid, it is rotated relative to the tool (or reciprocally) and is scanned by means of the latter.

Generally, the optical surface is rotated, its friction against the tool being sufficient to jointly drive it in rotation.

The surfacing operation requires an abrasive that can be contained in the buffer or in the fluid.

During surfacing, the elastically compressible interface compensates for the difference in curvature between the end surface of the tool support and the optical surface.

• la figure 1 est une vue en perspective éclatée de cet outil et d'une lentille ophtalmique présentant une surface optique à surfacer ;
• la figure 2 est une vue en coupe de cet outil représenté assemblé, au cours du surfaçage de la surface optique de la lentille de la figure 1 ; et
• la figure 3 est une vue schématique de dessus représentant cette lentille ophtalmique en cours de surfaçage au moyen de cet outil, lequel est représenté au cours du balayage de la surface optique dans deux positions dont l'une est illustrée en trait interrompu.

An exemplary embodiment of the tool proposed by the French patent application 2,834,662 , to which corresponds the US patent application 2005/0101235 , is described below in support of Figures 1 to 3 annexed drawings, in which:

• the figure 1 is an exploded perspective view of this tool and an ophthalmic lens having an optical surface to be surfaced;
• the figure 2 is a sectional view of this tool shown assembled, during the surfacing of the optical surface of the lens of the figure 1 ; and
• the figure 3 is a schematic top view showing this ophthalmic lens being surfaced by means of this tool, which is represented during scanning of the optical surface in two positions, one of which is illustrated in broken lines.

On the figure 1 is shown a tool 1 for surfacing an optical surface 2, in this case one of the faces of an ophthalmic lens 3. On the figure 1 , as well as on the figure 2 , the optical surface 2 concerned is represented concave, but it could just as well be convex.

The tool 1 is formed of a stack of at least three parts, namely a rigid portion 4, an elastically compressible portion 5, and a flexible portion 6, which, in what follows, will be called respectively support, interface and buffer.

As it appears in particular on the figure 1 the support 4 comprises two jaws, namely a lower jaw 7 and an upper jaw 8 adapted to be superimposed by being nested one inside the other by means of a pin 9 projecting from one of the faces the upper jaw 8, fit to be housed in a complementary hole 11 arranged, facing, in a face 12 of the lower jaw 7.

As can be seen on the figure 1 , the support 4 is generally cylindrical symmetry of revolution and has an axis of symmetry noted X, which defines a so-called longitudinal direction.

We denote the n normal to the optical surface 2 at the point of intersection of the axis of symmetry X of the tool 1 with the latter.

Opposite its face 12 in which the hole 11 is made, the lower jaw 7 has an end surface 13 extended substantially transversely, against which is applied, covering the interface 5.

The buffer 6 is applied against the interface 5 on the other side of the latter with respect to the support 4.

More specifically, the pad 6 covers at least part of the interface 5 opposite and to the right of the end surface 13.

The friction of the pad 6 against the optical surface 2 will, by means of an abrasive contained in the watering fluid or incorporated in the pad 6 itself, to ensure a superficial removal of material on the optical surface 2 in order to to modify the surface state, as we will see later.

The pad has, on the one hand, a central portion 6a which is at the right of the end surface 13, and a peripheral portion 14 which is, transversely, beyond the end surface 13.

This peripheral portion 14 is connected to the support 4 by means 15 of elastic return.

The peripheral portion 14 extends in the extension of the central portion 6a while being, at rest, substantially coplanar with it.

In the example shown on the figures 1 and 2 , the pad 6 is integral, the peripheral portion 14 being connected to the central portion 6a, so that they form in fact a single piece.

According to an embodiment shown in strong lines on the figure 1 , the tampon 6 is in the form of a flower, and thus comprises a plurality of petals 14b which protruding transversely from the central portion 6a, form the peripheral portion 14 of the pad 6 and each extend transversely beyond the end surface 13.

According to a variant shown in phantom on the figure 1 , the peripheral portion 14 is in the form of a ring 14a which surrounds the central portion 6a.

In this case, in the absence of stress, the buffer 6 is, when it is monobloc, in the form of a disk of material whose thickness is small in front of its diameter, as shown in FIG. figure 1 , the peripheral portion 14, 14a thus forming a flange with respect to the end surface 13.

The return means 15, which will be described later, can be interposed directly between the support 4 and the peripheral portion 14 of the buffer 6, that is to say, in practice, the flange 14a or the petals 14b.

The interface 5 comprises not only a central portion 5a which is at the right of the end surface 13, but also a peripheral portion 16 which is transversely beyond the end surface 13.

This peripheral portion 16 is in the extension of the central portion 5a, and is, for example, in the absence of stress, under the shape of a crown which surrounds the central portion 5a, and which is in fact interposed between the peripheral portion 14 of the buffer 6 and the return means 15.

As it appears on the figures 1 and 2 , the interface 5 is in one piece, its central parts 5a and peripheral 16 being in fact connected to form together a single piece, the peripheral portion 16 forming a flange with respect to the end surface 13.

Thus, in the absence of stress, the monoblock interface 5 is for example in the form of a disc of material whose thickness is small in front of its transverse dimension (that is to say, its diameter).

When the interface 5 and the buffer 6 are both monobloc, they have comparable transverse dimensions. In particular, when they are each in the form of a disc of material, they will preferably be chosen, for constructive convenience, of the same diameter. However, it will also be possible to use a pad of a diameter different from that of the interface, in particular of greater diameter in order to mitigate the edge effects of the tool on the worked surface.

In addition, for reasons which will appear subsequently, there is provided a deformable ring 17 interposed between the peripheral portion 16 of the interface 5 and the return means 15.

In practice, this ring 17 is fixed on the peripheral portion 16 on the other side thereof relative to the pad 6, that is to say on the same side as the support 4, and so that it it is surrounded by ring 17.

Preferably, this ring 17 is of circular longitudinal section, but it could also be of more complex section, in particular oblong, polygonal, rectangular or square. Moreover, it is arranged on the peripheral part 16 concentrically with the support 4.

The return means 15 are now described.

These comprise at least one elastically flexible strip 18 which projects transversely from the support 4 and which is connected, on the one hand, rigidly to the support 4 by a first end 18a and, on the other hand, to the peripheral portion 14 of the buffer 6 by a second end 18b, said free end, opposite the first 18a.

In this way, under the effect of a force exerted longitudinally on the peripheral portion 14 to the right of the plate 18, the latter is deformed by exerting on the peripheral portion 14 a reaction opposite to said force.

In practice, the return means 15 comprise a plurality of such strips 18 distributed uniformly around the periphery of the support 4, to act on the entire peripheral portion 14 of the buffer 6.

The return means 15 are in fact in the form of a starry part 19 rigidly fixed to the support 4.

This star piece 19 comprises a central portion 20 from which a plurality of branches 18 project each forming an elastically flexible strip extending radially in a transverse plane.

For fixing the star piece 19 to the support 4, its central portion 20 is, in practice, pinched between the jaws 7, 8 of the support 4, its centering being provided by means of a through hole 21 made in its center, crossed by the pin 9 of the upper jaw 8, the assembly being held by means of fastening means such as screws which, passing through the upper jaw 8 and the central portion 20 of the star piece 19, are caught in the jaw lower 7.

When, in accordance with an embodiment previously described, the one-piece stamp 6 comprises a plurality of petals 14b, there are provided on the star piece 19 as many branches 18 as petals 14b, the star piece 19 being oriented so that each branch 18 extends to the right of a petal 14b. Thus, when the pad 6 has seven petals 14b, the starry part 19 comprises, in turn, seven branches 18 each to ensure the elastic return of a petal 14b.

The ring 17 is attached to the interface 5, this attachment can be provided by any means, gluing being however preferred, especially for its simplicity.

In the embodiment shown, the diameters of the interface 5, the buffer 6, the star part 19, have a value at least twice that of the diameter of the support 4.

Moreover, when it comes to surfacing an ophthalmic lens, the diameters of the interface 5 and the buffer 6 are chosen substantially equal to the diameter of the lens 3, so that the diameter of the support 4 is much smaller than the diameter. of the lens 3.

The use of tool 1 is illustrated on the Figures 2 and 3 .

This is in the case of surfacing or smoothing of a convex face 2 aspheric of an ophthalmic lens.

The lens 3 is mounted on a rotary support (not shown) by means of which it is driven in rotation about a fixed axis Y.

The tool 1 is applied against this face 2 with sufficient force so that the buffer 6 matches its shape. The tool 1 is here, meanwhile, free in rotation yet being off-center with respect to the optical surface 2. A drive forced rotation of the tool, by own means, however, can be provided.

The relative friction of the optical surface 2 and the buffer 6 is sufficient to rotate the tool 1 in the same direction as that of the lens 3, about an axis substantially coincident with the axis X of symmetry of the support 4.

The optical surface 2 is sprayed with a non-abrasive or abrasive watering fluid, depending on whether or not the pad performs this function.

In order to scan the entire optical surface 2, the tool 1 is moved during the surfacing along a radial trajectory, the point of intersection of the axis of rotation X of the tool 1 with the optical surface 2 effecting a plane. movement back and forth between two cusp points, namely an external cusp A and an internal cusp B both located at a distance from the axis of rotation Y of the lens 3.

The central portion 6a of the tampon 6 is deformed by conforming to the shape of the optical surface 2 thanks to the compressibility of the central portion 5a of the interface 5.

As for the peripheral portion 14 of the tampon 6, it deforms by conforming to the shape of the optical surface 2 thanks to the deformation of the flexible strips 18.

Given the rigidity of the support 4, the removal of material takes place in majority right of the end surface 13, that is to say that this removal of material is carried out essentially by the central portion 6a of the buffer 6.

As for the peripheral portions 14 of the buffer 6 and 16 of the interface 5, they essentially have a stabilizing role, on the one hand thanks to the increase in the lift or seating of the tool 1 compared to a conventional tool whose buffer and the interface would be limited to the central portions 5a, 6a and, secondly, thanks to the return means 15 which maintain a permanent contact between the peripheral portion 14 of the buffer 6 and the optical surface 2.

The deformable ring 17 allows a smoothing of the stress distribution exerted on the peripheral periphery of the interface 5 and hence on the pad 6 by the strips 18.

As a result, regardless of the location of the tool 1 on the optical surface 2 and irrespective of its rotational speed, its axis of rotation X is permanently collinear or substantially collinear with the normal n at the optical surface 2 , the orientation of the tool 1 is thus optimal at all times.

In the embodiment illustrated on the figures 1 and 2 , the end surface 13 of the support 4 is flat.

The tool 1 is thus adapted to surface a certain range of optical surfaces 2 of different curvatures.

In order to modify the adaptability of the tool 1, it is possible to prestress the biasing means 15 by twisting the flexible strips 18 so that they are already bent at rest, in one direction or the other.

When, at rest, the lamellae 18 are straight or bent opposite the end surface 13, the tool 1 is intended for the concave optical surfaces 2, whereas when the slats 18 are bent on the side of the end surface 13, the tool 1 is intended for 2 convex optical surfaces.

In a first variant not shown, the end surface 13 of the support 4 is convex, the tool 1 thus being intended for optical surfaces 2 having a more pronounced concavity.

In a second variant not shown, the end surface 13 of the support 4 is concave, the tool 1 thus being intended for optical surfaces 2 to more pronounced convexity.

Of course, it is possible to combine the concave or convex embodiment of the end surface 13 with the preload of the return means 15, as described above.

The French patent application 2,857,610 , to which corresponds the US patent application 2006/0154581 , proposes that the elastic return means, rather than being in the form of a star-shaped piece such as the piece 19 illustrated on the figures 1 and 2 , has a continuous peripheral part cooperating in support with the peripheral part of the buffer such as the buffer 6, directly or via the only interface such as the interface 5 (no deformable ring such as 17 is provided), the elastic return means comprising, in addition to the continuous peripheral portion, a flat or curved collar rigidly fixed on the inner side to the support such as the support 4, this collar being formed by a perforated or solid wall.

The continuous character of the peripheral part of this return means makes it possible to increase the regularity of the surfacing carried out by the tool.

The French patent application 2,900,356 , to which corresponds the US patent application 2008/0171502 proposes that the rigid support belong to a base comprising a flexible collar surrounding the rigid support with the elastically compressible interface which covers an end surface of the flange located on the same side as the end surface of the rigid support.

Thanks to the flange, the contact surface between the interface and the rest of the tool is particularly important, which ensures a uniform distribution of the pressure exerted on the surface to be worked and thus makes it possible to perform surfacing with great aspect quality.

OBJECT OF THE INVENTION

The aim of the invention is to provide a surfacing tool which is particularly efficient in terms of minimizing appearance defects.

The invention proposes for this purpose an optical quality surfacing tool, comprising: a base comprising a flexible collar and a rigid support surrounded by said collar, which is subdivided into petals, said rigid support having a transverse end surface; an elastically compressible interface secured to the base, comprising a so-called central portion which is in line with said end surface of the rigid support and a so-called peripheral portion which is transversely beyond said end surface of the rigid support said elastically compressible interface being applied against and covering an end surface of said flange located on the same side as the end surface of the rigid support; a flexible pad adapted to be applied against a surface to be worked, subjected to the interface opposite the rigid support, comprising a so-called central portion which is located at the right of said end surface of the rigid support and a so-called peripheral portion which is transversely beyond said end surface of the rigid support; as well as elastic return means disposed between said rigid support and the peripheral portion of said interface, the combination of said peripheral portion of the buffer, said peripheral portion of the interface and elastic return means forming a means for stabilizing the tool during surfacing, said tool being adapted to perform a surfacing essentially at said central portion of the buffer; characterized in that said elastic return means comprise a plurality of resiliently flexible lamellae projecting transversely from the rigid support, with each lamella having a distal portion cooperating directly with a said petal; said distal portion being curved in a rounded loop such that the end of each said leaf is turned towards said rigid support.

The lamellae and the petals thus cooperate in such a way as to exert a stress on the interface in a way that is particularly favorable both to the general conformation of the tool and to its deformation capacity to follow the variations in altitude of the surface to be worked, including when there are strong variations in altitude, as is the case when one of the faces of a Eyeglass lens intended to correct the vision of a presbyopic, myopic and astigmatic wearer.

In particular, the conformation of the distal portions of the lamellae provides flexible, progressive and continuous deformation support (damping).

According to preferred features, each elastic lamella is an individual lamella attached to said rigid support.

The assembly of the lamellae with the rigid support is certainly more complex than if the lamellae were part of a starry part, but considering the existence of the curved distal portion of each lamella, the individual or distinct nature of the lamellae is particularly interesting, because of the convenience and simplicity of realization of the slats it offers.

According to other preferred features, each elastic lamella is permanently attached to said rigid support.

Alternatively, according to other preferred features, said rigid support and each elastic strip are arranged so that each elastic strip is attached to said rigid support removably and removably.

Preferably, said rigid support comprises for each lamella a cavity having a retaining recess while each lamella comprises a U-shaped portion adapted to be housed in a said cavity of the support, with a branch of said U-shaped portion having a suitable nose to enter said recess.

Preferably, for each blade, the tool comprises a wedge of elastically compressible material which is inserted forcefully between the branches of the U-shaped portion.

Preferably, each said wedge has a rounded distal portion as the base of the U-shaped portion and a proximal portion which has a tongue protruding between two shoulders.

Preferably, the tool comprises at the opening of each cavity a rib on the opposite side to that is formed said recess.

Preferably, said rib has a central passage for a tab for extracting said lamella from said cavity.

According to other preferred characteristics, there are more said petals than said lamellae.

Preferably, there are twice as many petals as lamellae.

According to other preferred features, said end surface of the flange is flush with said end surface of said support.

According to other preferred features, said rigid support comprises a cavity for receiving the head of a surfacing machine spindle.

According to other preferred features, said base is made of plastic material molded in one piece.

According to other preferred features, each slat is made of spring steel.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 4 est une vue de dessus d'une partie de l'outil conforme à l'invention, et plus précisément de l'embase et des lamelles ;
• la figure 5 est la vue en élévation-section repérée par V-V sur la figure 4 ;
• la figure 6 est une vue schématique en coupe d'une autre portion de l'outil selon l'invention, comportant l'interface élastiquement compressible et le tampon souple ;
• les figures 7 et 8 sont des vues semblables aux figures 4 et 5 montrant une variante de l'embase et des lamelles ;
• la figure 9 est, en agrandissement par rapport à la figure 8, une vue en élévation de l'une des lamelles que comporte l'outil, dans la position qu'elle prend au repos, c'est-à-dire en l'absence de contraintes externes ;
• la figure 10 est la vue repérée par X-X sur la figure 9 ; et
• les figures 11 et 12 sont, en agrandissement par rapport à la figure 8, des vues respectivement en élévation et en plan de la cale de maintien prévue pour chaque lamelle.

The description of the invention will now be continued by the detailed description of exemplary embodiments, given below by way of illustration and without limitation, with reference to figures 4 and following of the accompanying drawings. On these:

• the figure 4 is a top view of a portion of the tool according to the invention, and more specifically of the base and the lamellae;
• the figure 5 is the elevation-section view marked by VV on the figure 4 ;
• the figure 6 is a schematic sectional view of another portion of the tool according to the invention, comprising the elastically compressible interface and the flexible pad;
• the figures 7 and 8 are views similar to Figures 4 and 5 showing a variant of the base and slats;
• the figure 9 is, in enlargement compared to the figure 8 , an elevational view of one of the slats that the tool comprises, in the position it takes at rest, that is to say in the absence of external constraints;
• the figure 10 is the view spotted by XX on the figure 9 ; and
• the Figures 11 and 12 are, in enlargement compared to the figure 8 , views respectively in elevation and in plan of the holding wedge provided for each lamella.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In what follows, the same numerical references as for tool 1 were used for the tool according to the invention, but increased by 100.

• un support rigide 104 présentant une surface transversale d'extrémité 113 ;
• une interface élastiquement compressible 105 (figure 6) qui est appliquée contre et recouvre la surface d'extrémité 113 ;
• un tampon souple 106 (figure 6) apte à être appliqué contre la surface optique telle que 2 d'une lentille telle que 3 et qui est appliqué contre et recouvre au moins en partie l'interface 105 à l'opposé et au droit de la surface d'extrémité 113, le tampon 106 comportant une partie centrale qui se trouve au droit de la surface d'extrémité 113 et une partie périphérique qui se trouve transversalement au-delà de la surface d'extrémité 113 ; et
• des moyens de rappel élastique 115, formés ici par un ensemble de lamelles élastiquement flexibles 118, raccordant la partie périphérique du tampon 106 au support 104, la combinaison de la partie périphérique du tampon 106 et des moyens de rappel formant un moyen de stabilisation de l'outil 101 lors du surfaçage, l'outil 101 étant adapté à réaliser un surfaçage pour l'essentiel au niveau de la partie centrale du tampon 106.

In general, the tool 101 is arranged as the tool 1, with:

• a rigid support 104 having a transverse end surface 113;
• an elastically compressible interface 105 ( figure 6 ) which is applied against and covers the end surface 113;
• a flexible pad 106 ( figure 6 ) adapted to be applied against the optical surface such as 2 of a lens such as 3 and which is applied against and covers at least part of the interface 105 opposite and to the right of the end surface 113, the buffer 106 having a central portion which is right of the end surface 113 and a peripheral portion which is transversely beyond the end surface 113; and
• elastic return means 115, formed here by a set of elastically flexible strips 118, connecting the peripheral portion of the buffer 106 to the support 104, the combination of the peripheral portion of the buffer 106 and return means forming a means of stabilizing the 101 during the surfacing, the tool 101 being adapted to perform a surfacing essentially at the central portion of the buffer 106.

The support 104 belongs to a base 130 which has a flexible peripheral portion 131 located transversely beyond the rigid support 104, which is centrally disposed.

The peripheral portion 131 generally forms a flexible collar having an outer diameter (large diameter) similar to the outer diameter of the interface 105 and the buffer 106.

The inner diameter (small diameter) of the flexible collar 131 corresponds to the external diameter of the support 104, the flange 131 projecting from the lateral wall of the support 104.

In the example shown on the Figures 4 to 6 , the support 104 and the flexible peripheral collar 131 are made of one-piece molded plastic, the support 104 being solid at least in the vicinity of the surface 113 in order to have the required rigidity while the collar 131 is of small thickness. wall to be flexible.

In the preferred example illustrated on Figures 4 to 6 , the flange 131 has fourteen slots 133 oriented radially and distributed equi-angularly, so that the flange 131 is subdivided into fourteen petals 134 each generally formed as an angular sector trunk.

The subdivision of the collar 131 into petals allows this collar to be flexible in order to conform to different curvatures of surfaces to be polished.

The end surface 113 of the support 104 is flush with the surface 132 of the flange 131 on the same side.

The fact that the support 104 and the flange 131 are made in one piece makes it possible to reduce the effects of marking the edge of the end surface 113 on the surface to be worked, so that the tool 101 makes it possible to perform surfacing with a high quality of appearance.

Because of the difference in thickness between the flange 131 and the support 104, there is, on the opposite side to the surfaces 132 and 113, a shoulder 135 at the junction between the flange 131 and the support 104.

In general, the support 104 has the outer contour of a cap with a proximal portion 137 which has an outer diameter smaller than the distal portion 136 to which the end surface 113 and the shoulder 135 belong.

The proximal portion 137 serves to connect the support 104, and more generally the base 130, to the spindle of the surfacing machine allowing the tool 101 to cooperate with an optical surface such as 2 in the manner explained above at support from Figures 2 and 3 .

The proximal portion 137 has a cavity 140 for receiving the spindle head. The cavity 140 is generally shaped like three-quarters of a sphere.

The spindle head adapted to be accommodated in the cavity 140 has a spherical portion end shaped similarly.

The assembly between the proximal portion 137 and the spindle of the machine is by simple snapping, the thickness of the portion 137 is sufficiently small.

When the spindle head is engaged in the cavity 140, the tool 101 co-operates in a ball joint relation to the spindle.

It should be noted that the center of the cavity 140 is particularly close to the end surface 113, which allows the tool 101 to orient itself optimally with respect to the surface such as 2 with which the tool 101 must cooperate.

The elastic return means 115 will now be described in detail.

These comprise a plurality of elastically flexible strips 118, here seven in number, distributed equi-angularly, which project transversely from the support 104 to rest on the flexible collar 131, on the same side as the portion 137.

In practice, each lamella 118 is rigidly attached to the support 104 by screws 141 which plate its proximal portion 142, which is flat, on an annular surface 143 of the support 104 situated between the portion 137 and the shoulder 135.

The lamellae 118 are arranged angularly so that each is centered with respect to the associated petal 134.

It will be observed that the slats 118 have a length such that they extend each transversely beyond the flange 131.

The lamellae 118 each have a distal portion 144 curved towards the petal 134 associated in a rounded loop so that the end 145 of the lamella 118 is turned towards the support 104, the zone contact between the lamella 118 and petal 134 being located below the end 145.

Thanks to this conformation, each lamella 118 can slide freely on the associated petal 134 when they deform, since it is by a relatively flat area that each lamella 118 is in contact with the associated petal 134, on a terminal portion of that it is relatively flat.

It will be observed that if the end portion 144 had been shaped so that the end 145 is turned towards the lamella 118, and therefore if it was through the end 145 that the lamella 118 bore on the petal 134, the sliding would occur in poorer conditions because of the weak contact zone offered by the end 145.

In practice, here, each lamella 118 is first inclined towards the opposite of the associated petal 134 and then bends towards the associated petal 134 for about half a turn.

We will observe, as we see on the figure 5 , that here the contact zone is in the vicinity of the periphery of the flange 134.

The conformation of lamellae 118 and petals 134 is such that in the absence of external constraint (situation illustrated in FIG. figure 5 ) the assembly formed by the surfaces 113 and 132 is concave.

As indicated above, the diameter of the interface 105 and the buffer 106 corresponds to the external diameter of the flange 131.

The securing between the interface 105 and the base 130 is performed by a double-sided adhesive 150 disposed between the interface 105 and the surfaces 113 and 132 of the base 130.

In the example illustrated, the elastically compressible interface 105 is a foam having a thickness of the order of 9 mm with a glossy skin which is located on the side of the pad 106.

On the side opposite the skin, that is to say on the side of the double-sided adhesive 150, is heat-welded a film 151 of polyester (PET), having for example a thickness of 23 microns.

The connection between the elastically compressible interface 105 and the flexible pad 106 is done through a layer 152 of sizing putty, here a layer of 0.5 mm thick.

Still in the example shown on the figure 6 , the flexible pad 106 has a thickness of the order of 1 mm and the double-sided adhesive 150 has a thickness of the order of 0.32 mm.

The diameter of the interface 105 and the buffer 106 is of the order of 55 mm.

The base 130 is made of plastic molded in one piece by injection.

In the example shown, the base 130, which must both be rigid in the vicinity of the end surface 113 and flexible at the collar 131 and the proximal portion 137 to allow the snaps, while providing a good wear resistance for cooperation with the spindle head, is made of polypropylene (PP) or high density polyethylene (eg HDPE 1000).

The base thus has good wear resistance for cooperation with the spindle head and allows easy bonding with the interface 105.

The end surface 113 of the support 104 is shaped like a sphere portion having a radius of curvature of the order of 70 mm.

When the base 130 is at rest, that is to say in the absence of external stresses, the surface 132 of the flange 131 which, as indicated above, is flush with the surface 113, is shaped with the same curvature.

Thanks to the flange 131, the contact surface between the interface 105 and the rest of the tool, in this case the base 130, is particularly important since it is formed both by the surface 113 and by the surface 132.

This ensures a uniform distribution of the pressure exerted on the surface to be worked, such as the surface 2 of the lens 3.

In particular, risk is avoided, as with the previous tool illustrated on the Figures 1 to 3 , to mark the surface to be worked by the rim-shaped edge of the end surface 13.

This more generally allows the tool 101 to perform surfacing having particularly high aspect qualities.

Moreover, the fact of having both surface 113 and surface 132 facilitates the gluing of interface 105 with rigid support 104.

When the tool 101 is applied against a convex work surface such as the surface 2 shown on the Figures 1 to 3 , the elastically compressible interface 105 is strongly compressed at the central portion and the force exerted by the slats 118 is useful for forcing the peripheral portion of the pad 106 to remain in contact with the surface such that 2.

During surfacing, the fact that the lamellae 118 exert on the petals 134 a force directed towards the interface 105 at the periphery of the latter, allows the tool 101 to be particularly efficient in terms of maintaining the contact with the working surface such as 2, even when the latter has large variations in altitude, for example if it is a face of a spectacle lens to correct the vision of a wearer presbyopic, myopic and astigmatic.

The conformation of the end portion 144 offers the advantage, thanks to its rounded nature, to provide a smooth, progressive and continuous damping, favorable to the performance of the tool 101.

It will be noted that it would have been possible to conform the distal portion 144 not in a rounded manner but with a fold which would act as a hinge between two flat portions. Such a conformation would be less efficient because with such a hinge, one would lose the progressive and continuous character of depreciation.

We will now describe in support of figures 7 and 8 a variant 130 'of the base 130. The same reference numerals have been used for the similar elements, but with an exponent'.

The base 130 'is arranged as the base 130 but while each elastic strip 118 is permanently attached to the support 104 (here, the screws 141 can not be removed), the rigid support 104 'and each elastic strip 118' are arranged so that each elastic strip 118 'is attached to said rigid support 104' removably and removably.

The interchangeable nature that the slats then have is particularly interesting for maintenance issues and / or fine adjustments of the behavior of the tool.

In practice, the support 104 'comprises for each lamella 118' a cavity 146 having a retaining recess 147 while each lamella has a U-shaped portion 148 adapted to be housed in a cavity 146 of the support 104 ', with a branch of the U-shaped portion 148 which has a nose 149 adapted to penetrate the recess 147.

In addition to the recess 147, to retain each lamella 118 ', there is provided a rib 160 at the opening of each cavity 146, the rib 160 being on the opposite side to that which is formed the recess 147.

The rib 160 has at its center a passage in which takes place a tongue 155 (see more particularly the Figures 9 and 10 ) protruding at the end of the branch 156 of the U-shaped portion 148 opposite the branch having the nose 149.

As we see on the figure 10 , the tongue 155 protrudes between two shoulders 157 of the portion 156. It is the shoulders 157 which bear on the rib 160. The tongue 155 serves to extract the lamella 118 'of the housing 146.

We will observe, as the figure 9 at rest (in the absence of external stresses) the U-shaped portion 148 has an apex angle A which is larger than when the portion 148 is in place in the housing 146.

Still to retain each lamella 118 'in a cavity 146, there is also provided here a wedge 161 of elastically compressible material, which is inserted by force between the branches of the U-shaped portion 148.

The wedge 161 has a distal portion 162 which is rounded as the base of the U-shaped portion 148 and a proximal portion 163 which has a tongue 164 projecting between two shoulders 165.

The shoulders 165 serve as a stop against the rib 160. The tongue 164 takes place in the passage of the center of the rib 160. The tongue 164 serves to extract the shim 161.

In the illustrated examples, there are twice as many petals 134 or 134 'as lamellae 118 or 118' because this provides an excellent deformation capacity to follow a surface such as surface 2. In non-illustrated variants, following the circumstances, there are also more petals than slats but with a different ratio for example two lamellae for three petals, or there are as many petals as lamellae.

In non-illustrated variants of the embodiment with strips that can not be dismantled or permanently attached to the rigid support (embodiment shown in FIGS. Figures 4 and 5 ), the slats are fixed otherwise than by screws, for example by gluing, riveting, overmoulding or even thanks to the presence of an overmoulded clamping insert.

In non-illustrated variants of the embodiment with removable and reassemblable lamellae (embodiment illustrated in FIGS. Figures 7 to 11 ), the fixing is done by removable screws, the slots of the slats are formed by molded inserts (composite base), the support is in two parts latched, for example with a metal part (part which cooperates with the pin).

In yet another variant not illustrated, the elastic return means formed by individual slats are replaced by one or more starred parts.

In non-illustrated variants, the base of the tool according to the invention comprises a number of petals different from fourteen, for example six or sixteen and the slots defining the petals have different shapes, for example with corrugations.

In yet other variants not illustrated, the support 104 is shaped differently, for example in two parts forming jaws as in the previous tool illustrated on the Figures 1 to 3 .

In still other variants of the tool according to the invention, the elements other than the base are arranged differently, for example as illustrated in FIGS. Figures 1 to 3 .

Many other variants are possible depending on the circumstances, and it is recalled in this regard that the invention is not limited to the examples described and shown.

Claims (15)

1. Optical quality surfacing tool comprising: a base (130 ; 130') comprising a flexible collar (131 ; 131') and a rigid support (104 ; 104') surrounded by said collar (131 ; 131'), which collar (131 ; 131') is subdivided into petals (134 ; 134'), said rigid support (104 ; 104') having a transverse end surface (113 ; 113') ; an elastically compressible interface (105) connected to the base (130 ; 130'), comprising a part referred to as central which is located in line with said end surface (113 ; 113') of the rigid support (104 ; 104') and a part referred to as peripheral which is located transversely beyond said end surface (113 ; 113') of the rigid support (104 ; 104'), said elastically compressible interface (105) being applied against and covering an end surface (132 ; 132') of said collar situated on the same side as the end surface (113 ; 113') of the rigid support (104 ; 104') ; a flexible buffer (106) adapted to be applied against a surface to be worked, connected to the interface (105) on the opposite side to the rigid support (104 ; 104'), comprising a part referred to as central which is located in line with said end surface (113 ; 113') of the rigid support (104 ; 104') and a part referred to as peripheral which is located transversely beyond said end surface (113 ; 113') of the rigid support (104 ; 104') ; as well as elastic return means (115 ; 115') disposed between said rigid support (104 ; 104') and the peripheral part of said interface (105), the combination of said peripheral part of the buffer (106), of said peripheral part of the interface (105) and of the elastic return means (115 ; 115') forming a means for stabilizing the tool (101 : 101') during the surfacing, said tool (101 ; 101') being adapted to perform surfacing for the most part at the central part of the buffer (106); characterized in that said elastic return means (115 ; 115') comprise a plurality of elastically flexible strips (118 ; 118') which project transversely from the rigid support (104 ; 104'), each strip (118 ; 118') having a distal portion (144 ; 144') in direct bearing cooperation with a said petal (134 ; 134'); said distal portion being curved in a rounded curl such that the end (145 ; 145') of each said strip (118 ; 118') is turned towards said rigid support (104 ; 104').
2. Tool according to Claim 1, characterized in that each elastic strip (118 ; 118') is an individual strip mounted onto said rigid support (104 ; 104').
3. Tool according to Claim 2, characterized in that each elastic strip (118) is permanently mounted onto said rigid support (104).
4. Tool according to Claim 2, characterized in that said rigid support (104') and each elastic strip (118') are arranged in order for each elastic strip (118') to be mounted onto said rigid support in demountable and remountable manner.
5. Tool according to Claim 4, characterized in that said rigid support (104') comprises for each strip (118') a cavity (146) having a retaining recess (147) while each strip (118') comprises a U-shaped portion (148) adapted to be accommodated in a said cavity (146) of the support (104'), with one branch of said U-shaped portion comprising a nose (149) adapted to enter said recess (147).
6. Tool according to Claim 5, characterized in that for each strip (118'), it comprises a wedge (161) of elastically compressible material which forcibly inserts between the branches of the U-shaped portion (148).
7. Tool according to Claim 6, characterized in that each said wedge (161) has a distal portion (162) which is rounded like the base of the U-shaped portion (148) and a proximal portion (163) which has a tab (164) projecting between two shoulders (165).
8. Tool according to any one of Claims 5 to 7, characterized in that at the location of the opening of each cavity it comprises a rib (160) on the opposite side to that at which said recess (147) is formed.
9. Tool according to Claim 8, characterized in that said rib (160) has a central passage for a tab (155) for extracting said strip (118') out of said cavity (146).
10. Tool according to any one of Claims 1 to 9, characterized in that there are more said petals (134 ; 134') than said strips (118 ; 118').
11. Tool according to Claim 10, characterized in that there are twice as many petals (134 ; 134') as strips (118 ; 118').
12. Tool according to any one of Claims 1 to 11, characterized in that said end surface (132 ; 132') of the collar (131 ; 131') is flush with said end surface (113 ; 113') of said support (104 ; 104').
13. Tool according to any one of Claims 1 to 12, characterized in that said rigid support (104 ; 104') comprises a cavity (140 ; 140') for receiving the head of a surfacing machine arbor.
14. Tool according to any one of Claims 1 to 13, characterized in that said base (130 ; 130') is a onepiece plastics molding.
15. Tool according to any one of Claims 1 to 14, characterized in that each said strip (118 ; 118') is of spring steel.

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