EP0603074A1 - Process for checking the fitting of a lens to be grinded to a spectacle frame on a grinding machine - Google Patents

Abstract

This involves checking the fitting of a lens (10) to be ground, to a spectacles frame. According to the invention, this fit check is done on the grinding machine (11) itself, by mounting the lens (10) to be ground on its support spindle (15), bringing this lens (10) into contact with the grinding wheel (12) without this grinding wheel rotating at all, causing the support spindle (15) to rotate step by step until the lens (10) to be ground makes a complete revolution on itself and checking whether, during this revolution, the contact detector (17) associated with the template (jig) (16), is actuated by this lens. Application to grinding machines used for trimming the edges of a lens for spectacles. <IMAGE>

Description

The present invention relates generally to the control of the adequacy of the outline of the circles or of the surroundings of a spectacle frame of the glasses intended to equip it.

As is known, spectacle lenses are initially presented in the form of pucks of circular, elliptical or other contour, and of different sizes, which should be overflowed by grinding to adjust them to the contour of the circles or surrounds of the spectacle frames to be fitted.

Usually, they are overflowed on a grinder generally comprising at least one grinding wheel, which is rotatably mounted on a frame, a rocker, which is pivotally mounted on this frame around an axis parallel to the axis of rotation. of the grinding wheel, a support spindle, which is rotatably mounted on the rocker around an axis parallel to the axis of rotation of the grinding wheel, and which is adapted to receive axially, on the one hand, the glass to be ground, and, on the other hand, a jig, and, positioned directly above the jig, a contact detector, which, in practice, is mounted movably on the frame transversely to the pivot axis of the rocker.

For example, the template is a shaped template, that is to say a template whose outline corresponds exactly to that of the circles or surroundings of spectacle frame to be fitted, and, when it comes into contact with the contact detector , thus forming a stop, which is associated with it, it interrupts the movement of engagement of the glass with respect to the grinding wheel due to the gravity of the rocker alone or to the combined effect of this gravity and of means such as springs or counterweight and thus limits to the desired contour the overflowing of this glass at the corresponding place.

As a variant, the template is a round template, and the contact detector which is associated with it is then subjected to control means which, in conjunction with the outline of the circles or surrounds of spectacle frame to be fitted, control a movement thereof causing a pivoting in one direction or the other of the rocker so as to adjust accordingly to places where the glass overflows.

In all cases, it is up to the practitioner to choose at the outset a glass of sufficient size, that is to say a glass whose contour envelopes with certainty that of the circle or entourage to be fitted with regard to the centering according to which this glass must be mounted in this circle or circle.

Various ancillary devices specifically provided for this purpose have already been proposed for the necessary control on this subject.

They are most often simple centering devices, which, when slipping, and prior to this, that is to say prior to the installation on the glass of the gripping block with the aid of which it will then be put in place on the support pin of the grinder, allow superimposing, according to the centering, to respect an image of the outline of the lens to be mounted and an image of the outline of the circle or surrounding frame of glasses to be fitted, and which therefore allow thus to check on sight that there is indeed a good adequacy of this glass to this circle or entourage.

As a variant, in European patent application No. 0 379 427, two sensors are walked on the glass on either side of it according to the outline of the circle or surrounding of spectacle frame to be fitted, with the emission of 'a warning signal if the thickness detected by these sensors along this contour becomes zero or less than a determined limit thickness, thus indicating that the glass chosen is of insufficient size or that it is poorly centered.

These devices come in addition to the instrumentation strictly necessary for the sole overflowing of the glasses, at the expense of costs.

In the absence of such devices, it is also possible to proceed by calculation to the adequacy check to be carried out.

But, except for glasses of circular contour, this calculation is relatively complicated.

The subject of the present invention is a method making it possible to economically take advantage of the only grinder for this adequacy check, without the need to use any additional devices or without the need to carry out any calculation.

This process is generally characterized in that the glass to be ground is mounted on the support spindle of the grinder, this glass is brought into contact with the wheel of this grinder in the absence of any rotation of this wheel, the support spindle is rotated step by step until the glass to be ground turns on itself a full turn, and it is checked whether, during this turn, the contact detector associated with the template also fitted to the grinder is operated by it.

If this is the case, and assuming correct centering, the size of the glass is not suitable.

The method according to the invention, the various operations of which can easily be integrated into a special work cycle, or auscultation cycle, of the grinder, to be carried out prior to any grinding cycle thereof, thus makes it very possible quickly, without excessive handling, or intervention of any other device, to ensure, using the only grinder, taking advantage of the only components thereof, the adequacy check to be performed.

In other words, it advantageously makes it possible to charge the grinder, in addition to the specific functions thereof, an additional function, which is that of ensuring the desired adequacy control.

• la figure 1 est une vue en perspective d'une meuleuse permettant la mise en oeuvre du procédé suivant l'invention ;
• la figure 2 en est, à échelle supérieure, une vue partielle en coupe transversale, suivant la ligne II-II de la figure 1 ;
• la figure 3 est une vue simplifiée de bout de cette meuleuse, suivant la flèche II de la figure 1, pour un premier type de gabarit ;
• la figure 4 est une vue simplifiée de bout analogue à celle de la figure 2 pour un autre type de gabarit.

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 a perspective view of a grinder allowing the implementation of the method according to the invention;
• Figure 2 is, on a larger scale, a partial view in cross section, along line II-II of the figure 1 ;
• Figure 3 is a simplified end view of this grinder, along arrow II of Figure 1, for a first type of jig;
• Figure 4 is a simplified end view similar to that of Figure 2 for another type of template.

As illustrated in FIG. 1, it is generally a question of ensuring the overflowing of a spectacle lens 10 on a grinder 11 to allow mounting thereof in one of the circles or surrounds of a determined spectacle frame not shown.

In a manner known per se, the grinder 11 usually comprises at least one grinding wheel 12 which, under the control of a motor 13, is rotatably mounted on a frame not shown, along an axis of rotation A1 shown diagrammatically in broken lines on Figure 1, a rocker 14, which, according to the double arrow F1 of Figure 1, is pivotally mounted on the frame, around an axis A2 shown schematically in broken lines in Figure 1 and parallel to the axis of rotation A1 of the grinding wheel 12, a support spindle 15, which is rotatably mounted on the rocker 14 around an axis A3 also shown schematically in broken lines in Figure 1 and also parallel to the axis of rotation A1 of the grinding wheel 12 , and which is adapted to receive axially, on the one hand, the glass 10 to be ground, being for example, and as shown, formed by two half-spindles 15 ', 15' 'suitable for enclosing between them the glass 10 duly glued beforehand, and, on the other hand, and according to the provisions described more in detail later, a template 16, and, placed directly above this template 16, a contact detector 17.

This grinder 11 is for example of the type described in the French patent which, filed on March 22, 1983 under No 83 04637, was published under No 2 543 039.

This grinder 11 is thus well known in itself, it will not be described in more detail here.

It will suffice to indicate that the template 16 is disposed at the end of the support pin 15, and that the contact detector 17 which is associated with it is itself disposed at the end of a rod. support 18, which is mounted axially movable, and which, as shown diagrammatically in FIGS. 2 and 3, meshes with a rack 19 with a pinion 20 wedged on the output shaft of a motor 21.

In practice, this motor 21 is under the control of a control unit, not shown.

In practice, also, in the embodiment shown, and in a manner known per se, the contact detector 17 comprises, on the one hand, a key 22, on which the template 16 is capable of bearing by its edge and whose upper surface is a coaxial cylindrical surface of the grinding wheel 12 and of the same diameter as the latter so as to have a convex profile so as to allow it to cooperate as well as possible with the template 16, and, on the other hand, a plate 23 , which is carried by the support rod 18 and on which the key 22 is pivotally mounted around an axis A4 parallel to the pivot axis A2 of the rocker 14, with, acting between this key 22 and this plate 23, a displacement detector 24 and a spring 25.

The assembly constitutes what, for a grinder 11 of the kind concerned, is usually called a vernier head.

In the embodiment shown, the displacement detector 24 is constituted by an optoelectronic cell, which is carried by the plate 23, and between the transmitter 26 and the receiver 27 from which is likely to be inserted, when the key 22 is pressed in, a cut-off pallet 28 carried by the latter.

The depressing capacity of the key 22 with respect to the plate 23, deliberately exaggerated in FIG. 2, is in practice very reduced.

Two modes of implementation are possible.

According to a first of these modes, FIG. 3, the template 16 has an outline which, point by point, is strictly identical to that of the circle or surrounding of the spectacle frame to be fitted.

The contact detector 17 is in this case stationary, to then form a stop for the template 16, being for do this duly locked in position by the motor 21.

When, the glass 10 bearing on the grinding wheel 12 under the effect of gravity due to the rocker 14, the template 16 comes to bear on the key 22 of this contact detector 17, it limits point by point the corresponding engagement movement glass 10 relative to the grinding wheel 12, which ensures that the latter overflows at its contour.

According to a second possible embodiment, FIG. 4, the template 16 is a round template, and it is the contact detector 17 taken as a whole which, controlled accordingly by the motor 21 under the control of the unit associated piloting, then limit point by point the movement of engagement of the glass 10 relative to the grinding wheel 12.

For example, the control unit restores for this the shape data which are transmitted to it by a contour reading device to which the circle or entourage of spectacle frame to be fitted is corollary, and, at each of its swings in a direction or in the other, the key 22 of the contact detector 17 intervenes consequently on the direction of rotation of the motor 21 by means of the displacement detector 24 which is underlying it.

In all cases, the practitioner should check that the glass 10 to be ground, duly centered with respect to the axis of rotation A3 of the support pin 15 by the gripping block which has been applied to it accordingly, and therefore duly centered with respect to the template 16, is of adequate size.

For this adequacy check, the procedure according to the invention is as follows.

It will first be assumed, for convenience, that the template 16 is a shaped template.

After having mounted the glass 10 to be ground on the support spindle 15, this glass 10 is brought into contact with the grinding wheel 12 in the absence of any rotation thereof, and, as shown diagrammatically in FIG. 2 by lines P1, P2, P3 etc ... linked to the corresponding positions of the template 16, the support pin 15 is rotated step by step until the glass 10 grinding makes a complete turn on itself.

If, as has been assumed to be the case in FIG. 3, the size of the glass 10 is adequate, the template 16 remains permanently at a distance from the contact detector 17 during this turn.

In other words, the maximum circle C which it scans during it does not overlap with the key 22 that this contact detector 17 includes, which, as a result, is spared from any contact with the template 16, and therefore remains motionless, without ever being depressed.

According to the invention, it is therefore checked whether, during the turn of the glass 10 on itself, the contact detector 17 is or is not actuated by the template 16.

In other words, it is checked whether the key 22 of this contact detector 17 is pressed by the template 16.

If it is not the subject of such a depression, the size of the glass 10 is sufficient.

If on the contrary it is the object of a depression, this size is insufficient, and the glass 10 must be changed for another of larger size.

In practice, the control of a possible actuation of the contact detector 17 is ensured by the displacement detector 24 which it comprises.

Preferably, to save the glass 10, that is to say to avoid any unnecessary deterioration thereof, it ensures a lifting of the rocker 14 between each pitch of the support pin 15, so that the joint rotation of the glass 10 is not made in contact with the grinding wheel 12.

When the template 16 is a round template, the procedure is the same as above.

If desired, the various operations of the method according to the invention can advantageously be integrated into a special working cycle of the grinder 11, or auscultation cycle, to be carried out prior to any grinding cycle thereof.

The present invention is moreover not limited to the mode of implementation described but encompasses any variant of execution.

In particular, it would not depart from the scope of the invention if, for the formation of a bevel, the grinding wheel was replaced by a milling cutter.

So therefore, by "grinder", we mean here any "overflow machine", whether it is really a grinder or whether it is a beveler, and by "grinding wheel", it must be understood any cutting or machining tool, whether it is really a grinding wheel or whether it is for example a milling cutter.

Claims (4)

Method for checking the suitability of a lens for a spectacle frame on a grinder, characterized in that the grinder (11) comprising at least one grinding wheel (12) which is rotatably mounted on a frame, a rocker (14), which is pivotally mounted on said frame about an axis (A2) parallel to the axis of rotation (Al) of the grinding wheel (12), a support pin (15), which is rotatably mounted on the rocker (14) around an axis (A3) parallel to the axis of rotation (A1) of the grinding wheel (12), and which is adapted to receive axially, on the one hand, the glass (10) to grind, and, on the other hand, a template (16), and, placed directly above the template (16), a contact detector (17), the glass (10) to be ground is mounted on the support spindle (15), it is brought into contact with the grinding wheel (12) in the absence of any rotation thereof, the support spindle (15) is rotated step by step until the glass (10 ) to grind make a full turn on itself, and check whether, during this turn, the contact detector (17) associated with the template (16) is actuated by the latter. Method according to claim 1, characterized in that, between each pitch of the support spindle (15), a lifting of the rocker (14) is ensured. Method according to any one of Claims 1, 2, characterized in that, the contact detector (17) comprising a key (22) pivotally mounted on a plate (23) around an axis (A4) parallel to the pivot axis (A2) of the rocker (14), with, intervening between this key (22) and this plate (23), a displacement detector (24), a possible actuation of the contact detector (17) is detected at using the displacement detector (24) which it comprises. Method according to any one of Claims 1 to 3, characterized in that the various operations are integrated into a special working cycle of the grinder (11), or auscultation cycle, to be carried out prior to any grinding cycle of it.

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