阅读说明：本技术 用于气动地封阻半成品光学元件的装置 (device for pneumatically blocking semi-finished optical elements ) 是由 S·皮诺特 L·马丁 J·莫伊内 X·比尔泰 于 2018-06-12 设计创作，主要内容包括：封阻装置包括：支撑构件,所述支撑构件被配置用于向所述半成品光学元件(11)提供刚性支撑,所述支撑构件具有接触面,所述光学元件(11)的第一面(14)要施加到所述接触面上；以及气动封阻构件,所述气动封阻构件限定空腔(30),所述空腔被配置成由所述光学元件的所述第一面(14)封闭,所述气动封阻构件被配置用于维持所述空腔(30)内部的真空,使得所述光学元件被贴附到所述封阻装置上；所述支撑构件包括由形状记忆材料制成的支撑元件(23),所述形状记忆材料在低于预定温度时具有刚性状态并且在高于所述预定温度时具有塑性状态、并且在被加热到高于所述预定温度时在没有外力的情况下呈现预定记忆形状,所述支撑构件的所述接触面是所述支撑元件的表面(25)。(The blocking device comprises: -a support member configured for providing a rigid support to the semi-finished optical element (11), the support member having a contact face onto which a first face (14) of the optical element (11) is to be applied; and a pneumatic blocking member defining a cavity (30) configured to be closed by the first face (14) of the optical element, the pneumatic blocking member being configured for maintaining a vacuum inside the cavity (30) such that the optical element is affixed to the blocking device; the support member comprises a support element (23) made of a shape memory material having a rigid state below a predetermined temperature and a plastic state above the predetermined temperature and assuming a predetermined memory shape without external forces when heated above the predetermined temperature, the contact surface of the support member being a surface (25) of the support element.)

1. a blocking device for pneumatically blocking a semi-finished optical element (11) having a first face (14) and having a second face (15) opposite to the first face (14), to which the blocking device (13) is to be affixed, the second face being surface-treated by a surface treatment machine (10) configured for holding the semi-finished optical element (11) via the blocking device (13), the blocking device (13) comprising:

-a mounting portion (20) provided for mounting the blocking device (13) on a respective mounting member (17) of the surface treating machine (10); and

-a blocking portion (21) configured for blocking the semi-finished optical element (11);

the blocking portion (21) includes:

-a support member configured for providing a rigid support to the semi-finished optical element (11), the support member having a contact face onto which the first face (14) of the semi-finished optical element (11) is to be applied; and

-a pneumatic blocking member defining a cavity (30) configured to be closed by the first face (14) of the semi-finished optical element (11), the pneumatic blocking member being configured for maintaining a vacuum inside the cavity (30) when the cavity is closed by the first face (14) of the semi-finished optical element (11), so that the semi-finished optical element (11) is affixed to the blocking portion (21);

Characterized in that it comprises a support element (23) made of a shape memory material having a rigid state below a predetermined temperature and a plastic state above said predetermined temperature, said support element (23) assuming a predetermined memory shape in the absence of external forces when heated above said predetermined temperature, said contact surface of said support member being a surface (25) of said support element (23).

2. Blocking device according to claim 1, characterized in that it is configured for bringing the first face (14) of the semi-finished optical element (11) into direct contact with the contact face (25) of the support element (23) when the first face (14) of the semi-finished optical element (11) closes the cavity (30) of the pneumatic blocking means.

3. Blocking device according to any one of claims 1 and 2, characterized in that the cavity (30) is annular and extends around the support element (23).

4. A blocking device according to any one of claims 1 to 3, characterized in that it comprises a body (22) forming said mounting portion (20), said support element (23) projecting from said body (22); the pneumatic blocking means comprises an elastically deformable tubular wall (24) for defining the cavity (30), the wall (24) being attached to the body (22) and extending around the support element (23).

5. Blocking device according to claim 4, characterized in that said wall (24) comprises a bellows gasket having a rear edge (28) fixed to said body (22), and a front edge (29) configured to be in sealing contact with said semi-finished optical element (11) when said first face (14) of said semi-finished optical element (11) closes said cavity (30).

6. Blocking device according to any one of claims 4 and 5, characterized in that the pneumatic blocking member comprises a duct (32) in the body (22), which duct opens into the cavity (30), the duct (32) being configured to belong to a fluid communication between the cavity (30) and a vacuum pump (46) configured for pulling a vacuum into the cavity (30), and the pneumatic blocking member further comprises a valve (33) configured for controlling the pressure inside the duct (32).

7. Blocking device according to any one of claims 1 to 6, characterized in that said predetermined temperature is between 10 ℃ and 50 ℃.

8. the blocking device according to any one of claims 1 to 7, characterized in that said material has a Young's modulus in tension of between 5 and 100MPa below said predetermined temperature and between 0.3 and 3MPa above said predetermined temperature.

9. The blocking device according to any one of claims 1 to 8, characterized in that the material comprises a ferromagnetic element (27) such that the support element (23) is configured to be inductively heated above the predetermined temperature.

10. A blocking device according to any one of claims 1 to 9, characterized in that the blocking device (13) comprises a peltier effect unit (36) located on the opposite side of the support element (23) to the contact surface (25); the Peltier effect unit (36) is configured for cooling the support element (23) below the predetermined temperature and/or heating the support element (23) above the predetermined temperature.

11. Apparatus for affixing a blocking device (13) according to any one of claims 1 to 10 in a predetermined relative position to a semi-finished optical element (11) having a first face (14) to which the blocking device (13) is to be affixed and having a second face (15) opposite to the first face (14) to be surface-treated by a surface-treating machine (10) configured for holding the semi-finished optical element (11) via the blocking device (13), the apparatus comprising:

-a positioning system (45) configured for determining a current position of the semi-finished optical element (11) with respect to a reference frame (41) of the apparatus (38) and for positioning the semi-finished optical element (11) to the predetermined relative position with respect to the reference frame (41); and

-vacuum pulling means (46) configured for pulling a vacuum into the cavity (30) of the pneumatic blocking member of the blocking means (13) when the first face (14) of the semi-finished optical element (11) closes the cavity (30).

12. apparatus according to claim 11, characterized in that said blocking device (13) comprises a body (22) forming said mounting portion (20), said supporting element (23) projecting from said body (22), said pneumatic blocking member of said blocking device (13) comprising an elastically deformable tubular wall (24) for defining said cavity (30), said wall (24) being attached to said body (22) and extending around said supporting element (23), said pneumatic blocking member comprising a duct (32) in said body (22) opening into said cavity (30), said vacuum pulling device comprising a vacuum pump (46) configured to be connected to said duct (32) so as to pull a vacuum into said cavity (30) through said duct (32).

13. the apparatus according to any one of claims 11 and 12, characterized in that it comprises heating means configured for heating the supporting element (23) of the blocking device (13) above the predetermined temperature, said heating means comprising an electromagnetic coil (37), and the shape memory material of the supporting element (23) of the blocking device (13) comprising a ferromagnetic element (27), so that the supporting element (23) is configured to be inductively heated above the predetermined temperature by the electromagnetic coil (37).

14. Method for affixing a blocking device (13) according to any one of claims 1 to 10 in a predetermined relative position to a semi-finished optical element (11) having a first face (14) to which the blocking device (13) is to be affixed and having a second face (15) opposite to the first face (14) to be surface-treated by a surface-treating machine (10) configured for holding the semi-finished optical element (11) via the blocking device (13), the method comprising the steps of:

-providing said blocking device (13) in an initial state in which said material of said support element (23) is in said rigid state and said support element (23) assumes said memorized shape;

-subsequently heating the support element (23) above said predetermined temperature so that the material reaches said plastic state;

-then bringing said first face (14) of said semi-finished optical element (11) into contact with said contact face (25) of said support element (23) and pushing said semi-finished optical element (11) against said contact face (25) to conform said support element (23) until said contact face (25) reproduces the shape of the portion (47) of said first face (14) in contact with said contact face (25) and said semi-finished optical element (11) is in a predetermined relative position with respect to said blocking means (13);

-subsequently cooling the support element (23) below said predetermined temperature so that the material reaches said rigid state;

-subsequently drawing a vacuum into the cavity (30) of the pneumatic blocking means, said cavity being closed by the first face (14) of the semi-finished optical element (11).

15. Method according to claim 14, characterized by the step of pulling a vacuum by connecting a vacuum pump (46) to the duct (32) of the blocking device (13) so as to pull a vacuum into the cavity (30) through the duct (32).

Technical Field

The invention relates to blocking of semi-finished optical elements.

Background

semi-finished optical elements, such as semi-finished ophthalmic lenses, are known to have a finished face and an unfinished face opposite the finished face, to be surface-treated to obtain an optical element having desired optical properties.

It is also known to surface treat the unfinished face with a machine (sometimes called a generator) configured for holding the semi-finished optical element via a blocking device previously affixed to the finished face of the semi-finished optical element.

International patent application WO 2015/079134 discloses a holder for pneumatically blocking an optical lens on a surface treatment machine. The holder comprises a grip portion for fixing it to a respective member of the surface treatment machine, and a blocking portion for blocking the optical lens. The blocking portion comprises a body from which a buttress projects, said buttress being designed to provide a rigid seat for an optical lens which can abut against said seal so as to define, with said body, a vacuum chamber. The rest abutment comprises first bars mounted so as to be movable in translation with respect to the body so as to bear on the optical lens by their free ends, and return means are provided for returning the first bars against the optical lens.

The present invention relates to a blocking device for pneumatically blocking semi-finished optical elements, which is improved and optimized and is more convenient, simple, economical and easy to manufacture.

Disclosure of Invention

Accordingly, the present invention provides a blocking device for pneumatically blocking a semi-finished optical element having a first face and having a second face opposite to the first face, the blocking device being to be affixed to the first face, the second face having a surface treatment to be performed by a surface treatment machine configured for holding the semi-finished optical element via the blocking device, the blocking device comprising:

-a mounting portion arranged for mounting the blocking device on a respective mounting member of the surface treating machine; and

-a blocking portion configured for blocking the semi-finished optical element;

The blocking portion includes:

-a support member configured for providing a rigid support to the semi-finished optical element, the support member having a contact face onto which the first face of the semi-finished optical element is to be applied; and

-a pneumatic blocking member defining a cavity configured to be closed by the first face of the semi-finished optical element, the pneumatic blocking member being configured for maintaining a vacuum inside the cavity when the cavity is closed by the first face of the semi-finished optical element such that the semi-finished optical element is affixed to the blocking portion;

characterized in that said support member comprises a support element made of a shape memory material having a rigid state below a predetermined temperature and a plastic state above said predetermined temperature, said support element assuming a predetermined memory shape without external forces when heated above said predetermined temperature, said contact surface of said support member being a surface of said support element.

The blocking device according to the invention can be adapted to various semi-finished optical lens shapes, in particular by means of the variability properties of the support element, when the shape memory material is in the plastic state.

Due to the deformable nature of the shape memory material, the support element may be made of a single piece of material that is easily integrated into the blocking device. The manufacture of the blocking device is therefore very simple. In particular, there is no need to integrate complex mechanisms into the blocking device to make it adaptable.

Further, if the support element has been deformed so as to conform to the first optical element, the support element may automatically return to its predetermined memory shape by heating above a predetermined temperature due to the shape memory properties of the material. According to this predetermined memory shape, the support element may be adapted to the shape of the further semi-finished optical element. Thus, the blocking device is reusable.

The blocking device according to the invention is therefore convenient, simple, economical and easy to manufacture.

According to preferred features which are very simple, convenient and economical for embodying the blocking device according to the invention:

-the blocking device is configured for bringing the first face of the semi-finished optical element into direct contact with the contact face of the support element when the first face of the semi-finished optical element closes the cavity of the pneumatic blocking member;

-the cavity is annular and extends around the support element;

-the blocking device comprises a body forming the mounting portion, from which the support element protrudes; the pneumatic blocking member comprises an elastically deformable tubular wall for defining the cavity, the wall being attached to the body and extending around the support element;

-the wall comprises a bellows gasket having a rear edge fixed to the body, and a front edge configured to be in sealing contact with the semi-finished optical element when the first face of the semi-finished optical element closes the cavity;

-the pneumatic blocking member comprises in the body a duct opening into the cavity, the duct being configured to belong to a fluid communication between the cavity and a vacuum pump configured for pulling a vacuum into the cavity, and the pneumatic blocking member further comprises a valve configured for controlling a pressure within the duct;

-said predetermined temperature is between 10 ℃ and 50 ℃;

-said material has a young's modulus in tension below said predetermined temperature of between 5 and 100MPa and above said predetermined temperature of between 0.3 and 3 MPa;

-the material comprises a ferromagnetic element such that the support element is configured to be inductively heated above the predetermined temperature; and/or

-the blocking means comprise a peltier effect unit located on the opposite side of the support element to the contact surface; the Peltier effect unit is configured for cooling the support element below the predetermined temperature and/or heating the support element above the predetermined temperature.

The invention further provides an apparatus for affixing a blocking device as described above to a semi-finished optical element in a predetermined relative position, the semi-finished optical element having a first face and having a second face opposite to the first face, the blocking device being to be affixed to the first face, the second face being surface-treated with a surface-treating machine configured for holding the semi-finished optical element via the blocking device, the apparatus comprising:

-a positioning system configured for determining a current position of the semi-finished optical element relative to a reference frame of the apparatus and for positioning the semi-finished optical element to the predetermined relative position relative to the reference frame; and

-a vacuum pulling device configured for pulling a vacuum into the cavity of the pneumatic blocking member of the blocking device when the first face of the semi-finished optical element closes the cavity.

according to preferred features which are very simple, convenient and economical for embodying the device according to the invention:

-the blocking device comprises a body forming the mounting portion, the support element projecting from the body, the pneumatic blocking member of the blocking device comprising an elastically deformable tubular wall for defining the cavity, the wall being attached to the body and extending around the support element, the pneumatic blocking member comprising a duct in the body, the duct opening into the cavity, the vacuum pulling device comprising a vacuum pump configured to be connected to the duct so as to pull a vacuum into the cavity through the duct; and/or

-the blocking device comprises a heating device configured for heating the support element of the blocking device above the predetermined temperature, the heating device comprising an electromagnetic coil, and the shape memory material of the support element of the blocking device comprises a ferromagnetic element, such that the support element is configured to be inductively heated above the predetermined temperature by the electromagnetic coil.

The invention further relates to a method for affixing a blocking device as described above to a semi-finished optical element in a predetermined relative position, the semi-finished optical element having a first face and having a second face opposite to the first face, the blocking device being to be affixed to the first face, the second face being surface-treated with a surface-treating machine configured for holding the semi-finished optical element via the blocking device, the method comprising the steps of:

-providing the blocking device in an initial state in which the material of the support element is in the rigid state and the support element assumes the memorized shape;

-subsequently heating the support element above the predetermined temperature so that the material reaches the plastic state;

-subsequently bringing the first face of the semi-finished optical element into contact with the contact face of the support element and pushing the semi-finished optical element against the contact face to conform the support element until the contact face reproduces the shape of the portion of the first face in contact with the contact face and the semi-finished optical element is in a predetermined relative position with respect to the blocking device;

-subsequently, cooling the support element below the predetermined temperature such that the material reaches the rigid state.

-subsequently pulling a vacuum into the cavity of the pneumatic blocking member, the cavity being closed by the first face of the semi-finished optical element.

According to a further feature of the method according to the present invention, the step of pulling the vacuum is performed by connecting a vacuum pump to a conduit of the blocking device so as to pull the vacuum into the cavity through the conduit.

Drawings

The invention will now be described further with a detailed description of preferred embodiments, given below by way of non-limiting example and with reference to the accompanying drawings. In these figures:

Figure 1 is a schematic cross-sectional view of a surface treatment machine provided with a blocking device according to the invention and with a surface treatment tool, a semi-finished optical element having a first face affixed to the blocking device and a second face cooperating with the surface treatment tool;

Figure 2 illustrates a section of the blocking device cooperating with heating means configured for heating a supporting element of the blocking device, the blocking device being in an initial state in which the supporting element assumes a predetermined memory shape;

Fig. 3 schematically shows a cross section of the semi-finished optical element and the blocking device, both mounted in an affixing apparatus configured for bringing the semi-finished optical element up to a predetermined relative position with respect to the blocking device;

fig. 4 is a partial view similar to fig. 3, with the semi-finished optical element in a predetermined relative position with respect to the blocking device; and

Fig. 5 is a view similar to fig. 4, but with the blocking means connected to the vacuum pulling means of the attachment device.

Detailed Description

Fig. 1 shows a surface treatment machine 10, a blocking device 13 fitted to the surface treatment machine 10, and a semi-finished optical element 11 coupled to the blocking device 13 and processed with the surface treatment machine 10.

The surface treatment machine 10 is configured for holding the semi-finished optical element 11 via a blocking device 13.

here, the semi-finished optical element 11 is a semi-finished ophthalmic lens and has a first optical surface 14, a second optical surface 15 opposite the first optical surface 14, and a side surface 16 extending from one of the first optical surface 14 and the second optical surface 15 to the other.

the semifinished optical element is made here from polycarbonate.

The semi-finished optical element 11 is substantially circular in shape, the first face 14 being convex and the second face 15 being concave.

The blocking device 13 is here directly attached to the first optical face 14 of the semi-finished optical element 11.

The second side 15 is to be surface treated by the surface treating machine 10.

The semi-finished optical element 11 is provided with at least one reference mark 19, which is printed in ink or engraved on the optical face of the optical element 11 (here the first face 14) and is configured to be detected by a positioning system of the apparatus configured for determining the current position of the optical element 11 with respect to a reference frame of the apparatus. This is described in more detail below.

The surface treatment machine 10 comprises a holder 17 configured for holding the blocking device 13 in a predetermined position, and a displaceable surface treatment tool 18 configured for surface treating the second face 15.

The holder 17 is configured for driving the blocking device 13 into a spinning motion when the surface treatment tool 18 travels on the second face 15.

The semi-finished optical element 11 and the blocking means 13 are attached in a predetermined relative position.

in particular, the position of the optical element 11 with respect to the blocking means 13 is such that the optical element 11 and the blocking means 13 rotate coaxially.

as is known, the second face 15 is surface-treated with a surface treatment machine 10 in order to adjust the optical characteristics of the element 11, here the ophthalmic characteristics of the ophthalmic lens, according to the prescription of the user.

It will be noted that the material ablation resulting from the surface treatment operation is schematically visible in fig. 1, where the thickness of the semi-finished optical element 11 is reduced compared to the thickness in fig. 3 to 5 (in which the optical element 11 has not yet been treated).

The blocking device 13 is configured here for pneumatically blocking the semifinished optical element 11, and more particularly a vacuum blocking device.

The blocking device 13 comprises a mounting portion 20 and a blocking portion 21 opposite to the mounting portion 20.

The mounting portion 20 is provided for mounting the blocking device 13 onto a respective mounting means of the surface treating machine 10, here formed by the holder 17.

The mounting portion 20 is here configured such that the blocking device 13 is removable from the mounting member of the surface treating machine 10.

In a variant not shown, the blocking device is integrated into the surface treatment machine.

The blocking portion 21 is configured for blocking the semi-finished optical element 11 and comprises a support member configured for providing a rigid support for the semi-finished optical element 11 during the surface treatment operation.

The support is sufficiently strong to perform surface treatment operations. In particular, the support is sufficiently strong to prevent excessive vibrations of the semi-finished optical element 11 during the surface treatment operation.

The blocking device 13 will now be described in more detail with reference to fig. 2, in which it is shown in an initial state before it is coupled to the semi-finished optical element 11.

The blocking device 13 is substantially cylindrical in shape.

The blocking device 13 comprises a body 22, a support element 23 protruding from the body 22, and an elastically deformable tubular wall 24 attached to the body 22 and extending around the support element 23.

The support element 23 and the body 22 are both substantially cylindrical in shape and are coaxially arranged with respect to each other.

The body 22 is made of a rigid material and at least partially forms the mounting portion 20 of the blocking device 13.

The support element 23 forms a support member for the blocking portion 21.

The support element 23 is here distinct from the body 22 and is fastened thereto.

The support element 23 is made here of one piece.

The support element 23 has a lateral surface 25 opposite the body 22 and a lateral surface 26 extending from the lateral surface 25 to the body 22.

The transverse surface 25 is configured to be in contact with the first optical face 14 of the optical element 11.

The lateral surface 25 thus forms a contact surface of the support member on which the first optical face 14 is to be applied during the process of affixing the blocking device 13 to the optical element 11.

The side surface 26 is here at a distance from the tubular wall 24. More generally, the side surface 26 is free.

The support element 23 is made of a shape memory material, here comprising a shape memory polymer.

Such shape memory materials have a rigid state below a predetermined temperature and a plastic state above the predetermined temperature.

due to the shape memory properties of the material, the support element 23 assumes a predetermined memory shape in the absence of external forces when heated above a predetermined temperature.

In other words, when the material is in a plastic state, the support element 23 has a natural tendency to resume its predetermined memorized shape after deformation.

The predetermined temperature is here the glass transition temperature of the material, which is approximately 35 ℃.

more generally, the predetermined temperature is between 10 ℃ and 50 ℃.

Below a predetermined temperature (in the rigid state), the material here has a tensile young's modulus of approximately 50 MPa. Above a predetermined temperature (in the plastic state), the material here has a tensile young's modulus of approximately 1.5 MPa.

More generally, the material has a young's modulus in tension below a predetermined temperature of between 5 and 100MPa and above a predetermined temperature of between 0.3 and 3 MPa.

In order to reach the initial state of the blocking device 13 illustrated in fig. 2, the supporting element 23 has been heated above a predetermined temperature while not being subjected to any external force, and then cooled below the predetermined temperature. Thus, the support element 23 is rigid and assumes its predetermined memory shape.

it will be noted that the transverse surface 25 is here substantially planar, that is to say not curved, when the support element 23 assumes the predetermined memory shape.

The material of the support element 23 here comprises a ferromagnetic element 27, such that the support element 23 is configured to be inductively heated above a predetermined temperature.

The ferromagnetic elements 27 are represented on the drawing by dots filling the support element 23.

The ferromagnetic element 27 is here in the form of a powder dispersed in the material. The ferromagnetic element 27 is made of stainless steel here.

The ferromagnetic element 27 here represents approximately 30% by volume of the shape memory material. More typically, the volume ratio is between 10% and 40%.

The tubular wall 24 comprises a bellows gasket having a rear edge 28 fixed to the body 22 and a front edge 29 opposite the rear edge 28.

the tubular wall 24 is here substantially cylindrical in shape and is axially oriented so that axial deformation of the tubular wall 24 will bring the front edge 29 closer or further from the body 22.

The front edge 29 is configured to be in sealing contact with the first optical surface 14 of the optical element 11 when said first optical surface is attached to the blocking device 13.

it will be noted here that in the initial state of the blocking device 13, the front edge 29 slightly axially exceeds the transverse surface 25 of the support element 23 on the opposite side of the body 22.

The tubular wall 24 delimits an inner space 31 in which the support element 23 is at least partially received.

A portion of the inner space 31 extending between the lateral surface 26 of the support element 23 and the tubular wall 24 forms a cavity 30, which extends around the support element 23.

In other words, the tubular wall 24 defines the cavity 30. More specifically, the tubular wall 24 defines an exterior side of the cavity 30, while the side surface 26 defines an interior side of the cavity 30 opposite the exterior side.

The cavity 30 is here annular.

The blocking device 13 further comprises a duct 32 formed in the body 22 and a valve 33 connected to the duct 32. The conduit 32 is connected to the valve 33 by a first end 34, while said conduit opens into the cavity 30 by an opposite end 35 of the first end 34.

The valve 33 is configured to control the pressure within the conduit 32. The valve 33 is in particular configured for preventing fluid circulation in both directions through the duct 32.

The blocking device 13 further comprises first cooling means and/or heating means for the support element 23.

The first cooling means and/or heating means comprise a peltier effect element 36, here located on the opposite side of the support element 23 to its lateral surface 25.

the unit 36 is located in the blocking device 13 and is here more specifically housed in the body 22 of the blocking device 13.

The unit 36 is therefore integrated into the blocking device 13 and more particularly into the portion of the body 22 situated on the opposite side of the support element 23 to the transverse surface 25.

The unit 36 may be powered by electrical terminals (not shown) that are accessible at the side of the body 22.

the unit 36 is configured for cooling the support element 23 below a predetermined temperature and/or heating the support element 23 above a predetermined temperature. As is well known, the heating or cooling effect provided by the peltier effect element 36 is dependent on the direction of current flow within the element 36.

It should be noted here that the ferromagnetic element 27, in addition to the ability to inductively heat, also increases the thermal conductivity of the shape memory material, so that the support element 23 can be effectively heated or cooled by the peltier element 36.

in fig. 2 to 5, the blocking device 13 is shown cooperating with a second heating device, which is part of an apparatus 38 configured for affixing the blocking device 13 to the optical element 11.

The second heating means comprises an annular electromagnetic coil 37. The electromagnetic coil 37 is configured to be positioned with respect to the blocking device 13 around the portion of the blocking device 13 comprising the support element 23. In other words, the electromagnetic coil 37 and the support member 23 are arranged coaxially and at substantially the same height.

The diameter of the coil 37 is here sufficient for the coil 37 to surround both the support element 23 and the tubular wall 24.

The electromagnetic coil 37 is configured for generating an electric current in the ferromagnetic element 27 dispersed within the shape memory material so as to induce a heating effect within the support element 23.

the electromagnetic coil 37 is configured for heating the support element 23 above a predetermined temperature.

the electromagnetic coil 37 integrated into the blocking device 13 and the ferromagnetic element 27 together form a heating system which is partially integrated into the blocking device 13.

At the beginning of the process of attaching the blocking means 13 to the optical element 11, the blocking means 13 is provided in an initial state in which the support element 23 is at a temperature of about 20 ℃ lower than the predetermined temperature, so that the material of the support element 23 is in a rigid state.

During the heating step of the attaching process, the support element 23 is heated so as to reach a temperature of about 55 ℃ exceeding a predetermined temperature (the glass transition temperature of the material is here about 35 ℃), so that the material of the support element 23 reaches a plastic state.

The support element is here heated to approximately 20 c above the predetermined temperature.

More generally, the support element should be heated to about 20 ℃ to 30 ℃ above a predetermined temperature in order for the material to exhibit an optimal plastic state.

Thus, since the predetermined temperature is typically between 10 ℃ and 50 ℃, the support element should be heated to reach a temperature between 30 ℃ and 80 ℃.

The apparatus 38 configured for attaching the blocking device 13 to the optical element 11 will be further described with reference to fig. 3 to 5.

The apparatus 38 is configured for affixing the blocking device 13 and the semi-finished optical element 11 in a predetermined relative position.

Thus, the apparatus 38 comprises a holder 39 configured for holding the optical element 11, and a holder 40 configured for holding the blocking device 13.

In the device 38, the holder 40 is mechanically connected to a reference frame 41, as schematically shown in fig. 3 with dashed lines. The holder 39 is also mechanically connected to a reference frame 41, as schematically shown in fig. 3 with dashed lines.

The mechanical connection between the holder 40 and the reference frame 41 makes the position of the holder 40 relative to the reference frame 41 determinable. Since the holder 40 and the blocking device 13 are configured such that the blocking device 13 is positioned in a predetermined manner relative to the holder 40 when the blocking device 13 is held by the holder 40, the position of the blocking device 13 relative to the reference frame 41 is determinable. In particular, the position of the transverse surface 25 relative to the reference frame 41 is determinable.

The mechanical connection between the holder 39 and the reference frame 41 makes the position of the holder 39 with respect to the reference frame 41 determinable.

The mechanical connection between the holder 39 and the reference frame 41 comprises a drive system 42 for driving the holder 39 relative to the reference frame 41.

In order to determine the current position of the optical element 11 held by the holder 39 relative to the reference frame 41, the apparatus 38 comprises a camera 43.

the drive system 42 and the camera 43 are both connected to a control unit 44.

The drive system 42, the camera 43, and the control unit 44 are comprised in a positioning system 45 configured for positioning the semi-finished optical element 11 with respect to the reference frame 41.

The camera 43 is configured for capturing an image of the first face 14 of the optical element 11.

the control unit 44 is configured for detecting the reference mark 19 on the captured image and for determining the current position of the reference mark 19 relative to the reference frame 41.

Since the position of the blocking device 13 relative to the reference frame 41 is determinable, the control unit 44 can determine the current position of the reference mark 19 relative to the blocking device 13.

The control unit 44 is configured for controlling the drive system 42 in order to position the optical element 11 and the blocking device 13 in a predetermined relative position.

it should be noted here that in this predetermined relative position, the transverse surface 25 of the blocking device 13 is aligned with the reference mark 19.

In the step of the attachment process shown in fig. 3, the optical element 11 is mounted onto the holder 39 and the blocking device 13 is mounted onto the holder 40.

here, when the blocking device 13 is mounted onto the holder 40, the above-described heating step of the support element 23 is then performed.

The control unit 44 determines the current position of the optical element 11, more precisely of the reference mark 19, and drives the optical element 11 towards a starting position of the optical element 11 relative to the blocking device 13, in which position the optical element 11 is at a distance from the moulding device 13 and the reference mark 19 is aligned with the transverse surface 25 of the blocking device 13.

The control unit 44 is further configured for controlling the drive system 42 for driving the optical element 11 from the start position towards a predetermined relative position with respect to the blocking device 13 by bringing the optical element 11 and the blocking device 13 closer to each other.

the control unit 44 is further configured for bringing the first face 14 of the semi-finished optical element 11 into contact with the lateral surface 25 of the support element 23 and for pushing the semi-finished optical element 11 against the lateral surface 25 to conform the support element 23 until the lateral surface 25 reproduces the shape of the portion of the first face 14 in contact with the lateral surface 25 and until the semi-finished optical element 11 is in a predetermined relative position with respect to the blocking device 13.

the blocking device 13 and the optical element 11 then reach a predetermined relative position, as shown in fig. 4.

It should be noted that during the movement of the optical element 11 towards the blocking device 13, the first optical face 14 is first in contact with the front edge 29 of the elastically deformable tubular wall 24, which is then axially compressed. The leading edge 29 is then biased towards the first face 14 and automatically maintains contact with this first face 14.

The first optical face 14 then comes into contact with and exerts a force against the lateral surface 25 of the support element 23.

Since the side surface 26 is free and at a distance from the tubular wall 24, the support element 23 can extend radially to accommodate axial deformations due to the force exerted by the optical element 11.

It should also be noted that the first optical face 14 is here in direct contact with the lateral surface 25 of the support element 23, but if desired the first face 14 may be lined with a functional element, for example a protective tape.

Here, the electromagnetic coil 37 is left in place and actuated during the conforming of the support element 23. When the blocking means 13 and the optical element 11 reach a predetermined relative position, the coil 37 is deactivated.

The peltier element 36 is then actuated in order to cool the support element 23 until the shape memory material reaches a temperature of about 20 ℃ lower than the predetermined temperature. Thus, the material of the support element 23 is in a rigid state.

During this cooling step, the blocking device 13 and the optical element 11 are maintained in a predetermined relative position by the drive system 42. Thus, the drive system 42 keeps applying pressure to the optical element 11 so as to counteract the natural tendency of the support element 23 to resume its predetermined memory shape.

in the predetermined relative position, the first optical face 14 of the optical element 11 is in contact with the front edge 29 of the tubular wall 24 and with the transverse surface 25 of the support element 23 so as to close the annular cavity 30.

As explained above, the front edge 29 is further in sealing contact with the first optical face 14, so that the cavity 30 is closed in a sealing manner.

The apparatus 38 further comprises a vacuum pulling device, here comprising a vacuum pump 46 configured to be connected to the duct 32 via a conduit in which the valve 33 is disposed (fig. 5).

Thus, the conduit 32 forms a fluid communication between the cavity 30 and the vacuum pump 46, which can thus draw the air contained in the cavity 30 through the fluid communication.

the tubular wall 24, the duct 32, the valve 33 and the cavity 30 here form the pneumatic blocking member of the blocking portion 21 of the blocking device 13. As explained below, the pneumatic blocking means are configured for maintaining a vacuum inside the cavity 30 when said cavity is closed by the first face 14 of the semi-finished optical element 11, in order to adhere the semi-finished optical element 11 to the blocking portion 21 of the blocking device 13.

After the cooling step, the peltier unit 36 is deactivated and the vacuum pump 46 is connected to the tubing 32.

The vacuum is then pulled through the conduit 32 within the cavity 30 to create a vacuum-based retention effect on the first face 14 of the optical element 11 and to securely affix the blocking device 13 to the optical element 11.

Valve 33 is then actuated to prevent fluid communication through conduit 32 such that a vacuum within cavity 30 is maintained.

The vacuum pump 46 may then be disconnected from the conduit 32.

during the vacuum pull, the blocking device 13 and the optical element 11 are maintained in a predetermined relative position by the drive system 42 in order to avoid any undesired displacement of the optical element 11 with respect to the blocking device 13.

once the blocking device 13 holds the optical element 11, it can be released from the holder 39.

The solenoid 37 may then be removed. Accordingly, the diameter of the electromagnetic coil 37 is larger than the diameter of the optical element 11 so that the optical element can pass through.

The blocking device 13 coupled to the optical element 11 can then be released from the holder 40 and mounted onto the holder 17 of the surface treatment machine 10 in order to treat the semi-finished optical element 11 (fig. 1).

The support element 23 is here in contact with the optical element 11 through a central portion 47 of the first face 14 (fig. 5).

the lateral surfaces 25 of the support element 23 therefore follow the shape of this central portion 47.

further, the rigid support provided by the support element 23 is imparted to the optical element 11 by this central portion 47. The rigid supports are here distributed continuously over a central portion 47 of the first face 14.

The first face 14 further has a peripheral portion 48 extending radially from the central portion 47 to the side face 16 of the optical element 11.

The peripheral portion 48 at least partially conforms to the annular cavity 30. A vacuum-based retention effect is thus exerted on the peripheral portion 48.

To decouple the optical element 11 and the blocking device 13, the valve 33 is actuated to enable fluid communication through the conduit 32 to break the vacuum within the cavity 30 and disable the vacuum-based retention effect.

The blocking device 13 may then be returned to its initial state, as explained previously with reference to fig. 2, by heating the support element 23 again above the predetermined temperature so that the shape memory material reaches the plastic state and the support element 23 automatically assumes its predetermined memory shape.

In variants not shown:

The support element is not fastened to the body but is integral with the body, both the support element and the body being made of a shape memory material;

The support member comprises more than one support element made of shape memory material, for example two, three or more separate support elements, each forming part of the contact face;

the cavity further comprises a radial portion extending from the annular portion into the support element, said radial portion opening through a lateral surface of the support element;

Bellows gaskets replacing elastically deformable tubular walls, for example with silicon sealing rings;

In the initial state of the blocking device, the transverse surface is not flat but concave or convex;

the material of the optical element is different from polycarbonate and is for example an organic material or a mineral material;

the shape memory material is a mixture of polymers of different nature;

The predetermined temperature is different from the glass transition temperature of the material and is for example the melting temperature of the material;

The apparatus for attaching the blocking device to the optical element is integrated in a surface treatment machine comprising a single holder configured for holding the blocking device during the attachment process and the surface treatment operation;

The first cooling and/or heating means are distinct from the peltier effect unit and comprise, for example, a resistive heater and/or a circuit for the flow of a refrigerant fluid;

The first cooling and/or heating means comprise more than one peltier-effect element, for example a first element dedicated to cooling and a second element dedicated to heating; or comprises more than two units;

The second heating means, which are distinct from the electromagnetic coil and the shape memory material is free of ferromagnetic elements, comprise for example infrared radiation means;

-the heating step of the support element is performed by a peltier effect unit; and/or

The electromagnetic coil is removed before the support element is conformed.

more generally, it should be noted that the invention is not limited to the examples described and represented.