FR2884163A1 - OPTICAL GLASS GRINDING MACHINE WITH INCLINED FINISHING WHEEL AND CORRESPONDING OPTICAL GLASS - Google Patents

Abstract

This machine (11) comprises a lens holder (19) provided with means (31) for rotating a lens (15) about a first axis (A-A ') and a finishing wheel ( 49) having a peripheral groove (55) for forming a bevel (16) on a peripheral surface (13) of the lens (15). The finishing wheel (49) is rotatably mounted about a second axis (C-C '). The machine (11) comprises means (23) for relative movement of the finishing wheel (49) relative to the lens holder (19) to bring the finishing wheel (49) into an active beveling position. relative displacement (23) comprise tilting means (43) adapted to incline the second axis (C-C ') with respect to the first axis (A-A').

Description

The present invention relates to a machine for grinding optical glasses,

of the type comprising:

  an optical glass support provided with means for rotating a lens around a first axis; - A finishing wheel having a peripheral groove for forming a bevel on a peripheral surface of the glass, the finishing wheel being rotatably mounted about a second axis; and means for relative movement of the finishing wheel with respect to the glass support to bring the finishing wheel into an active beveling position.

  EP-A-1 310 326 discloses a grinding machine of the aforementioned type, comprising a grinding wheel having a grinding wheel and a grinding wheel provided with a circular groove. This machine makes it possible to produce lenses or optical glasses comprising a bevel on a peripheral surface. This bevel is received in a corresponding groove, said bezel, provided in the spectacle frame.

  To grind such a lens, a blank is machined along its periphery on the roughing wheel to give it the shape of the frame. Then, the roughed lens is fed to the finishing wheel to make the bevel.

  Such a machine does not give complete satisfaction, especially for grinding high curvature lenses and having angular shapes, for example square or rectangular.

  Indeed, because of the strong curvature of the lens in these angular parts, the lens comes into contact with distinct regions of the finishing wheel during the passage thereof in the angular portions. The shape and profile of the bevel in these angular parts is thus altered.

  An object of the invention is to obtain a bevelling machine which, even with an ophthalmic lens of strong curvature and angular shape, allows to obtain a peripheral bevel of satisfactory aesthetic appearance, with a sectional profile suitable for received precisely in a corresponding groove provided in the frame, this bevel does not weaken the mechanical strength of the glass.

  For this purpose, the invention relates to a machine of the aforementioned type, characterized in that the relative displacement means comprise inclination means adapted to incline the second axis relative to the first axis.

  The machine according to the invention may comprise one or more of the following characteristics, taken individually or in any technically possible combination: the relative displacement means comprise means for adjusting the angle of inclination of the second axis relative to the first axis; the adjustment means comprise means for calculating the angle of inclination as a function of the curvature and / or the radius of the glass along its periphery; - The finishing wheel has a substantially cylindrical peripheral finish surface into which the groove opens, the width of the peripheral surface being greater than the maximum width of the peripheral surface of the glass; - The finishing wheel comprises at least one chamfered end 20 for making a bevelling of the glass; - The machine comprises a wheel set rotatably mounted about a wheel axis substantially parallel to the first axis, and an additional tool assembly, the finishing wheel being rotatably mounted on the additional toolholder assembly; and the additional tool-holder assembly comprises a creasing disk.

  The invention also relates to an optical lens made by means of the machine above. This optical glass, provided with a bevel on its periphery, is characterized in that, in at least one meridian half-section of the glass, the peripheral surface, on either side of the bevel, is inclined relative to the optical axis of the glass.

  In one embodiment, said peripheral surface is inclined with respect to the optical axis over substantially the entire periphery of the glass.

  The invention will be better understood on reading the description which will follow, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a partial schematic view in elevation of parts of a first grinding machine according to the invention; - Figure 2 is an enlarged view of a marked detail II in Figure 1; - Figure 3 is a perspective view of an angular lens to be ground in the first machine according to the invention; and Figure 4 is a partial perspective view of a second grinding machine according to the invention comprising a wheel set.

  The first grinding machine 11 according to the invention, shown in FIGS. 1 and 2, is intended to carry out a finishing of the peripheral surface 13 of an ophthalmic lens or lens 15 by polishing and beveling operations, this lens 15 having been previously roughed by peripheral grinding.

  The lens 15 has, after treatment, a bevel 16 radially projecting extending in a median region of the peripheral surface 13. The profile of the bevel 16 is for example V. The machine 11 comprises a frame 17, a lens holder 19, a toolholder assembly 21, means 23 for axial and radial relative positioning of the assembly 21 relative to the support 19, and a control unit 25.

  The lens holder 19 comprises a carriage 27 pivotally mounted on the frame 17, provided with two half-shafts 29A, 29B adapted to grip the lens 15, and a motor 31 for rotating the lens 15.

  The carriage 27 is hinged relative to the frame 17, by a rear longitudinal edge 28, about an axis X-X 'of substantially horizontal tilting.

  The two half-shafts 29A, 29B are mounted along the front longitudinal edge 32 of the carriage 27. These half-shafts 29A, 29B extend along a substantially horizontal first axis AA 'parallel to the X axis. X '.

  The half-shafts 29A, 29B are provided with respective free ends 33A, 33B disposed opposite one another, adapted to grip the lens 15.

  The drive motor 31 of the lens 15 slowly rotates the half-shafts 29A, 29B around the first axis A-A 'by a transmission mechanism (not shown).

  As illustrated in FIG. 1, the tool-holder assembly 21 comprises a support 35, a linkage arm 37 projecting from the support 35, a tool-carrying shaft 39, a motor 41 for rapid rotation of the drive. 39, and means 43 for tilting the tool-holder shaft 39 relative to the support 35.

  The link arm 37 is articulated by a first end 45 on the support 21, about a horizontal pivot axis B-B 'substantially orthogonal to the first axis A-A'.

  The tool shaft 39 is rotatably mounted at the free end 47 of the link arm about a second axis C-C 'substantially orthogonal to the link arm 37.

  The shaft 39 carries a finishing wheel 49 and a creasing disc 51. It also carries at its free end a drilling tool 53. The members 49, 51 and 53 have as their common axis the axis C-C '.

  As illustrated in FIG. 2, the finishing grinding wheel 49 comprises a cylindrical finishing or polishing peripheral surface 54 in which a circular groove 55 is formed. The groove 55 has a shape profile complementary to the profile of the bevel 16 to be produced on the lens 15 The width el of the cylindrical part of the grinding wheel 49, taken parallel to the axis C-C ', is greater than the maximum width e2 of the peripheral surface 13 of the lens 15, taken along its edge.

  In the example illustrated in Figure 1, the width el is substantially constant and between 4 and 18 mm.

  The creasing disc 51 is thin. In the example 30 illustrated in FIG. 1, the thickness of this disc 51 is substantially constant and between 0.5 and 1.6 mm.

  The presence of the creasing disk 51 and the finishing wheel 49 on the tool-holder assembly 21 makes it possible, with the same machine 11, to produce a lens 15 having a bevel 16 or having a groove in its surface. device 13.

  Alternatively, as shown in phantom in Figure 2, each end of the grinding wheel 49 can be chamfered, so that it can also perform counter-beveling operations of the front and rear edges of the lens.

  With reference to FIG. 1, the arm 37, and consequently the toolholder shaft 39, is rotatable about the axis BB 'over an angular displacement of at least 30 and preferably 180, with the possibility of in particular take an upper vertical position in which the second axis CC 'is substantially parallel to the first axis A-A', and a plurality of inclination positions in which the second axis CC 'is inclined relative to the first axis A-A' .

  In the example illustrated in FIG. 1, the tool-holding shaft 39 remains substantially in the vertical plane passing through the first axis A-A ', whatever its position about the axis B-B'.

  The motor 41 for rotating the tool shaft 39 is fixed on the link arm 37. It is connected to the shaft 39 by transmission means 59 arranged in the arm 37.

  The adjustment means 43 of the inclination angle of the tool-holding shaft 39 comprise a motor 61 for actuating a worm 63, and a toothed wheel 65 tangent, mounted integral with the linkage arm 37. The worm 63 extends in a direction substantially parallel to the first axis A-A '.

  The toothed wheel 65 is fixed on the arm 37 at its free end 45. It extends in a plane substantially parallel to the plane defined by the first axis A-A 'and the second axis C-C'.

  The means 23 for axial and radial relative positioning of the tool-holder assembly 21 with respect to the lens support 19 comprise, for example, means 71 for tilting the carriage 27 about its tilting axis X-X ', and means 73 axial translation of the tool holder assembly 21 along an axis DD 'parallel to the first axis A-A'.

  The control unit 25 controls firstly the movement of the tool-holder assembly 21 along the axis D-D ', and secondly the displacement of the carriage 19 around the axis X-X . This last movement is comparable to a pseudo-translation movement along an axis perpendicular to the first axis A-A '.

  The control unit 25 also slaved the axial and radial positioning means 23 to selectively position the grinding wheels 49 and 51, and the drilling tool 53 in contact with the periphery 13 of the lens 15.

  The control unit 25 is connected to the actuating motor 61 of the tilting means 43 for controlling the rotation of the worm 63 in a first direction or in the opposite direction to the first direction, so as to adjust the inclination of the second axis CC 'relative to the first axis A-A'.

  The control unit 25 is connected to a computer 77 which makes it possible to calculate one or each inclination angle of the finishing wheel 49, as described below.

  An example of beveling method according to the invention will now be described with reference to Figures 2 and 3.

  This method comprises a step of choosing the bevel contour, a step of calculating one or each treatment angle corresponding to this bevel contour, a step of adjusting the angle of inclination of the finishing wheel 49 by compared to the rough lens 15, and a step of grinding the bevel 16.

  Initially (Figure 1), the rough lens 15, which has its final contour, is wedged between the two ends 33A, 33B of the half-shafts 29A, 29B by an adapter suitably positioned on the lens 15. The axis AA 'coincides with example with the optical axis of the lens.

  With reference to FIG. 3, in the step of choosing the contour, the optician chooses a contour 109 of bevel determined by selecting the position of the bevel on the periphery 13, for a number of points 111 chosen around the axis AA Each point 111 corresponds to an angular position of the lens 15 about the first axis A-A '.

  This number of points 111 is for example between 128 and 1024 and in particular equal to 512.

  The outline 109 of the bevel depends in particular on the shape of the glass and the frame chosen for this glass.

  In the calculation step, the computer 77 calculates a treatment angle as a function of the curvature and / or the radius of the glass along the contour 109.

  This processing angle may vary for each point 111 corresponding to an angular position of the lens 15 about the first axis A-A ', or can be maintained at a constant value, as described in French Application No. 04 05427.

  Then, in the adjustment step, the actuating motor 61 is actuated to drive the worm 63 and thereby the support arm 37 in rotation until the angle formed by the first axis AA and the second axis CC 'corresponds to the processing angle corresponding to the first point 111 of beveling.

  In the grinding step, the finishing grinding wheel 49 is brought into contact with the periphery 13 of the lens 15 by the displacement means 23.

  The motor 31 driving rotation of the lens 15 is then actuated, and the bevel 16 is formed on the periphery 13 of the lens 15, along the contour 109, by varying or not the inclination of the second axis CC relative to the first axis AA 'for each angular position of the lens 15 about the first axis A-A'.

  The machine 11 according to the invention makes it possible to obtain, for each lens 15 considered, a bevel 16 which has an aesthetic appearance and a profile in satisfactory section to be received accurately in a groove of corresponding shape provided in a corresponding spectacle frame .

  The bevel 16 made has a substantially constant transverse profile, even in the angular parts of the lens 13. Moreover, being in the extension of the edge of the glass, it does not affect the mechanical strength of the latter.

  The peripheral surface of the lens 13 is inclined relative to the axis A-A ', which allows a good maintenance of the glass in a wide variety of frame shapes including strong curvature.

  In a variant shown in FIG. 4, the grinding machine 11 further comprises a wheel set 201 comprising, for example, a roughing wheel 203, a finishing wheel 205 and a polishing wheel 207. The wheel set 201 is mounted in translation of the support 35 and the tool holder assembly 21 is retractable under the mill set 201 by rotation about the axis B-B '.

  The grinding wheels 203, 205 and 207 are rotatably mounted relative to the support 35 around a wheel axis E-E 'parallel to the first axis A-A'. The axis E-E 'extends in a vertical plane passing substantially through the first axis A-A'.

  The method then comprises a step of roughing the lens 13, before the step of grinding the bevel 16.

Claims (9)

  1. Machine (11) for grinding optical glasses, of the type comprising: - an optical glass support (19) provided with means (31) for rotating a lens (15) around a first axis (A-A '); - a finishing wheel (49) having a peripheral groove (55) for forming a bevel (16) on a peripheral surface (13) of the glass (15), the finishing wheel (49) being rotatably mounted around a second axis (C-C '); and means (23) for relative movement of the finishing wheel (49) relative to the glass carrier (19) to bring the finishing wheel (49) into an active beveling position; characterized in that the relative displacement means (23) comprise tilting means (43) adapted to incline the second axis (C-C ') with respect to the first axis (A-A').   2. Machine (11) according to claim 1, characterized in that the relative displacement means (23) comprise means (43) for adjusting the angle of inclination of the second axis (C-C ') relative to the first axis (A-A ').   3. Machine (11) according to claim 2, characterized in that the adjusting means (43) comprise means (77) for calculating the angle of inclination as a function of the curvature and / or the radius of the glass ( 15) along its periphery.   4. Machine (11) according to any one of the preceding claims, characterized in that the finishing wheel (49) has a substantially cylindrical peripheral surface (54) in which the groove (55) opens, the width (el ) of this peripheral surface (54) being greater than the maximum width (e2) of the peripheral surface (13) of the glass (15).   5. Machine (11) according to any one of claims 1 to 4, characterized in that the finishing wheel (49) comprises at least one chamfered end 30 for making a bevelling of the glass.   6. Machine (11) according to any one of the preceding claims, characterized in that it comprises a wheel set (201) rotatably mounted about a wheel axis (E-E ') substantially parallel to the first axis ( A-A '), and an additional tool-holder assembly (21), the finishing wheel (49) being rotatably mounted on the additional tool-holder assembly (21).   7. Machine (11) according to claim 6, characterized in that the additional toolholder assembly (21) comprises a creasing disc (51).   Optical glass (15) provided with a bevel (16) on its periphery, characterized in that, in at least one meridian half-section of the glass, the peripheral surface (13), on either side of the bevel , is inclined with respect to the optical axis (A-A ') of the glass.   io 9. An optical glass according to claim 8, characterized in that said peripheral surface (13) is inclined with respect to the optical axis over substantially the entire periphery of the glass.