Device for mounting an adapter on a lens blank

Device for mounting an adapter (18) on a lens blank (12), in particular for a lens centering machine (10). The device is of the type comprising a housing (22) in which is slidably mounted a mounting shaft (24) having an end (26) which is adapted to receive the adapter (18). The housing (22) is mounted to be movable between a position for loading the adapter (18) at the end (26) of the slidable shaft (24) and a position for mounting the adapter (18) in which the slidable shaft (24) extends in a direction (X--X) perpendicular to a support surface (P) for the lens blank (12). The device further comprises a frame (11) on which the housing (22) is mounted to be pivotable about a first pivot pin (34,Z--Z) parallel to the support surface (P) between the adapter-loading position and the adapter-mounting position, and an arrangement (50,64,72) for consecutively actuating the pivoting of the housing (22) and the sliding of the slidable shaft (24).

FIELD OF THE INVENTION 
The present invention relates to a device for mounting an adapter on a lens 
blank. 
The invention more particularly relates to a device for mounting such an 
adapter intended for a machine for centering lenses. 
BACKGROUND OF THE INVENTION 
An example of such a machine for centering lenses is described and shown in 
the document EP-A-0 206 860. This machine mainly comprises a horizontal 
planar surface, such as for example a flat screen, on which rests a lens 
blank, and a device for mounting an adapter on the blank, the device being 
mounted to be movable between an adapter-loading position and an 
adapter-mounting position. 
The device for mounting the adapter is for example constructed in 
accordance with the teaching of the patent application FR-A-2,613,268 and 
comprises a housing in which is slidably mounted a shaft whose end is 
arranged to receive an adapter. 
When the mounting device is in position for mounting the adapter, the axis 
of the slidable shaft is coincident with a reference axis of the centering 
machine which is perpendicular to the blank support. 
The user of such a machine first of all effects a precise geometrical 
positioning of the lens blank with respect to the reference axis, then, in 
a second step, brings the adapter-mounting device to the mounting 
position, and lastly effects the mounting proper by causing a vertical 
downward sliding of the slidable shaft the end of which had been loaded 
with an adapter. 
It has been found that the mounting device which equips such a machine is 
not very aesthetic and is particularly large. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a device for mounting an 
adapter on a lens blank which overcomes the aforementioned drawbacks. 
To this end, the invention provides a device for mounting an adapter on a 
lens blank, of the type comprising a housing in which is slidably mounted 
a mounting shaft whose end is arranged to receive an adapter, the housing 
being mounted to be movable between a position for loading the adapter at 
the end of the slidable shaft and a position for mounting the adapter in 
which the slidable shaft extends in a direction perpendicular to a support 
surface for the lens blank, characterized in that the device comprises a 
frame on which the housing is mounted to be pivotable about a first pivot 
pin parallel to the support surface between the adapter-loading position 
and the adapter-mounting position, and means for consecutively actuating 
the pivoting of the housing and the sliding of the slidable mounting 
shaft. 
According to other features of the invention: 
the actuating means comprise a control arm having a first end mounted on 
the housing to be pivotable about a second pivot pin parallel to the first 
pivot pin and a second end articulated to a portion of the slidable shaft, 
an elastic return spring biasing the slidable shaft to a position in which 
it is retracted into the housing, means for driving in rotation the 
control arm about the second pivot pin to cause the pivoting of the 
housing, in which housing the slidable shaft is in the retracted position, 
and consecutively cause the sliding of the slidable shaft, in opposition 
to the return biasing force applied thereto by the return spring, between 
its retracted position and an extended position for mounting the adapter, 
and a fixed stop for the housing against which the housing comes to bear 
thereby defines the adapter-mounting position; 
the means for articulating the second end of the control arm to the 
slidable shaft comprise a cylindrical articulation pin which extends in a 
direction parallel to the second pivot pin and is received between two 
parallel guiding and driving surfaces which are formed on the slidable 
shaft and extend in a plane perpendicular to the slidable shaft; 
the driving means comprise a motor which is connected to the control arm by 
the connecting rod of a connecting rodcrank system, the connecting rod 
having a free end which is articulated to the control arm; 
the line passing through the axis of the articulation of the free end of 
the connecting rod to the control arm and the second pivot pin of the 
control arm is substantially perpendicular to the line passing through the 
second pivot pin and the axis of the cylindrical guide pin; 
the device comprises means for varying the torque of the driving motor; 
the driving motor is a reversible electric motor whose current supply is 
controlled in such manner as to vary the adapter-mounting force; 
the motor is controlled by means of a "fugitive" push-button switch, and 
the housing is pivotally mounted on the frame by means of a pivotal arm 
having a first end mounted to be pivotable about the first pivot pin and a 
second end fixed to the housing. 
The invention also provides a machine for centering lenses, characterized 
in that it comprises a support surface on which a lens blank is placed 
with a precise geometrical positioning with respect to a reference axis 
perpendicular to the support surface for the lens, and a device for 
mounting an adapter which is constructed in accordance with the teaching 
of the present invention and is arranged on the machine in such manner 
that the axis of the slidable mounting shaft coincides with the reference 
axis when the housing is in the adapter-mounting position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The Figures illustrate a machine 10 for centering lenses or optical 
glasses, such as for example a blank 12 of a lens which is to be 
subsequently ground on a grinding machine so as to adapt it to the shape 
of a rim of the frame of a pair of eyeglasses in which the cut lens must 
be mounted with precision. 
Such a machine 10 comprises a centering station 14 which mainly comprises a 
flat horizontal screen, whose upper side constitutes a support plane P on 
which rests the lens blank 12 to be centering. 
The blank centering operation has essentially for purpose to achieve a 
precise positioning of the blank 12 with respect to a reference axis X--X 
which is perpendicular to the support plane P, and whose trace on the 
screen 16 is for example illustrated by two intersecting lines as shown in 
FIG. 2. 
After having precisely centred the blank 12, an adapter 18 must be mounted 
on the lens blank 12 in order to subsequently shape the blank in a 
grinding machine (not shown). 
The operation for its mounting the adapter or sucker 18, also termed 
"sucker mounting operation", has for purpose to apply the adapter or 
sucker 18 in a precise manner and with a controlled force on the top side 
of the glass lens blank 12. 
To this end, the adapter 18 is mounted in a mounting device 20 mainly 
comprising a housing 22 and a slidable shaft 24 whose free end 26 is 
arranged to receive the adapter 18. 
As to the operation of these components of the device for mounting the 
adapter 18, reference may be made to the document FR-A-2,613,268 the 
disclosure of which is included in specification by this reference. 
To summarize, the shaft 24 is mounted in the housing 22 to be slidable in 
the direction Y--Y between a retracted position of the shaft 24 relative 
to the housing 22, as shown in FIGS. 1 and 2, and an adapter-mounting 
position in which the mounting shaft 24 is partly extended out of the 
housing 22 in the direction Y--Y, as shown in FIG. 3. 
The slidable shaft 24 is elastically biased to its retracted position 
illustrated in FIGS. 1 and 2 by a helical tension spring 28, whose ends 
are respectively hooked to a lug 30 on the housing 22 and to a lug 32 
fixed to the shaft 24. 
In order to make it easy to use the lens centering machine 10, the whole of 
the mounting device 20 must be movable relative to the centering station 
14 between a position for loading an adapter 18 illustrated in FIGS. 1 and 
2, and an active adapter-mounting second position illustrated in FIG. 3. 
Indeed, in the adapter-loading position, apart from the fact that it must 
be possible to have ready access to the free end 26 of the slidable 
mounting shaft 24 for loading an adapter 18, the space above the support 
surface P must be unobstructed so that the user can easily carry out the 
geometrical centering of the lens blank 12, for example by means of a 
sighting device (not shown in the drawings). 
According to the invention, the adapter-mounting device 20 is completely 
withdrawn from the upper region of the centering station 14 to the first 
position for loading adapters, as illustrated in FIGS. 1 and 2 in which 
the main components of the device, in particular the housing 22, are 
substantially completely located on the left side as viewed in FIG. 1 
outside the station 14. 
Indeed, the housing 22 is mounted relative to the frame part 11 of the 
machine 10 to pivot about a first pivot means or pin 34. 
The housing 22 is fixed between two identical pivotal arms 36 which have 
first ends 38 mounted to be pivotable about the pin 34 and second ends 40 
fixed to the housing 22. 
The fork mounting of the housing 22 between its two pivotal arms 36 
therefore allows the housing to pivot about an axis Z--Z which is 
perpendicular to the reference axis X--X and to the axis Y--Y along which 
the mounting shaft 24 is slidable. 
The pivoting of the housing 22 about the pin 34 is defined by a first fixed 
stop 42 for the housing 22, which defines the adapter loading first 
position illustrated in FIG. 1, and a second fixed stop 46 which 
cooperates with a front edge 48 of one of the two pivotal, arms 36 so as 
to define the adapter-mounting second position illustrated in FIG. 3. 
In the embodiment illustrated in the Figures, the housing 22 pivots about 
90.degree. angle between its two positions defined by the stops 42 and 46. 
The arrangement illustrated in the Figures further comprises two parallel 
arms 50, which consecutively actuate or bring about the pivoting of the 
housing 22 and then the sliding of the mounting shaft 24. 
The two control arms 50 are mounted in the manner of a fork on each side of 
the pivotal arms 36. The first end 52 of each control arm 50 is mounted to 
be pivotable about a second pivot means or pin 54, whose axis S--S is 
parallel to the axis Z--Z of the first pivot pin 34. The second end 56 of 
each control arm 50 includes a cylindrical driving and guiding pin 58 
whose axis T--T is parallel to the axes Z--Z and S--S. 
The two cylindrical pins 58 are received between two guiding and driving 
plates 60 and 62 formed on the slidable mounting shaft 24. The two plates 
60 and 62 are parallel to each other and perpendicular to the axis Y--Y 
along which the slidable shaft 24 is slidable. 
The means for driving the control arms 50 in rotation about the pivot pin 
54 will now be described. These driving means comprise an electric motor 
64 provided with a speed reducer 66 the output shaft 68 of which is 
parallel to the pivot pin 54 and drives in rotation a member 70 in the 
shape of a circular sector. 
The member 70 is the crank of a connecting rod-crank system which is 
completed by a driving connecting rod 72, which has a first end 
articulated to the crank 70 by a first pivot pin 74 and a second end which 
is articulated to one of the control arms 50 by a second pivot pin 76, 
whose axis U--U is parallel to the axes S--S and T--T. 
The line L1 which passes through the axes S--S and U--U is substantially 
perpendicular to the line L2 which passes through the axes S--S and T--T. 
The member 70 constituting the driving crank has an incomplete circular 
sector shape as shown in FIGS. 1 and 2. For this purpose, it defines two 
radial surfaces 76 and 78 which define therebetween an empty angular 
sector capable of alternately cooperating with a fixed stop 80 constituted 
by a cylindrical stud fixed to the frame 11 of the machine 10. 
The operation of the mounting device 20 will now be described. 
Starting at the loading position illustrated in FIGS. 1 and 2, and after 
having loaded an adapter 18 on the end 26 of the slidable mounting shaft 
24, the user causes, by control means (not shown), the crank 70 to be 
driven in rotation by the motor 64 in the counterclockwise direction AH 
shown in the Figures. 
The rotation of the crank 70 drives the connecting rod 72 upwardly from its 
position shown in FIG. 1 to its position shown in FIG. 3. The motion of 
the connecting rod 72 first of all pivots the control arms 50 about the 
pin 54 in the clockwise direction H shown in FIGS. 1 and 2. 
The pivoting of the control arms 50 results in a corresponding displacement 
in the clockwise direction of the driving pins 58, which describe an arc 
of a circle of about 90.degree. between the loading position illustrated 
in FIG. 1 and the adapter-mounting position illustrated in FIG. 3. 
Owing to the force exerted by the return spring 28, and in a first stage of 
the pivoting of the arms 50, the driving pins 58 simultaneously drive the 
slidable shaft 24 and the housing 22 in which the shaft remains in its 
retracted position. 
In the course of this first stage, this assembly therefore pivots in the 
clockwise direction about the pivot pin 34 until the front edge 48 of one 
of the pivotal arms 36 of the housing 22 abuts against the fixed stop 46, 
which defines the adapter-mounting position of the housing 22 illustrated 
in FIG. 3. 
The pivoting of the control arms 50 in the clockwise direction continues 
under the action of the force applied thereto by the connecting rod 72 and 
the driving pins 58, and this causes in this second stage the slidable 
mounting shaft 24 to extend out of the housing 22 in opposition to the 
elastic return force applied to the shaft 24 by the helical tension spring 
28. 
This second stage of the rotation of the control arms 50 therefore 
consecutively brings about the vertical movement of the slidable mounting 
shaft 24 relative to the housing 22, until the adapter 18 comes into 
contact with the top surface of the blank 12. 
For a description of the mechanism whereby it is possible to release the 
adapter 18 from the end 26 of the slidable mounting shaft 24, reference 
may be for example made to the aforementioned document FR-A-2,613,268. 
As illustrated in FIG. 3, the mounting device 20 is of course arranged in 
the machine 10 in such manner that, in the adapter-mounting position, the 
axis Y--Y along which the slidable mounting shaft 24 is slidable is 
coincident with the reference axis X--X of the centering station 14. 
The motor 64 is for example an electric motor which is controlled by means 
of its electric current so as to permit adjusting the force with which the 
adapter 18 is mounted on the blank 12. 
The motor 64 is for example controlled by a push-button switch which must 
be maintained in position, also termed a "fugitive" switch, which 
immediately causes the driving motor 64 to rotate in the opposite 
direction when it is released. This rearward motion will continue until 
the abutment surface 76 abuts against the stop pin 80. 
The fact that the user must maintain the push-button depressed for 
effecting a mounting operation is a safety measure against risk of 
pinching the hands in the mechanism and also avoids applying an 
excessively prolonged force on the glass blank which is fragile. 
The means for controlling the supply of electric current to the motor 64 
may also include means for timing the starting up of the motor 64. 
The device has been illustrated in FIG. 3 in the case where there is no 
lens blank 12 on the support surface P. 
In order to ensure that the end 26 of the slidable shaft 24 does not damage 
the upper surface of the screen 16, the abutment surface 78 is arranged to 
abut against the stop pin 80 and thereby stop an excessive pivoting of the 
control arms 50 in the clockwise direction H. 
The various movements of the components of the device, when the direction 
of rotation of the motor 64 is reversed after the adapter 18 has been 
mounted, occur in the direction opposed to those described for the 
adapter-mounting stage until the upper surface 44 of the housing 22 once 
again abuts against the fixed stop 42 on the frame 11. 
The teaching of the invention therefore provides an automatic 
adapter-mounting device which is particularly compact and may be 
substantially completely withdrawn into a frame 11 which may be provided 
with a cover (not shown) and which does not hinder the user in the initial 
blank-centering stage and results in a particularly aesthetic design of 
the centering machine 10. Notwithstanding this considerable compactness, 
the device according to the invention nonetheless ensures a rectilinear 
travel of the slidable mounting shaft 24 of the order of 25 to 30 mm, and 
mounts without any risk an adapter 18 on the lens blanks whose thicknesses 
may vary between 3 and 18 mm. 
In the adapter-loading position illustrated in FIGS. 1 and 2, it will be 
observed that the end 26 of the slidable mounting shaft 24 is in a 
position in which it is particularly easy for the user to load an adapter 
18.