FR3086194A1 - OPTICAL GLASS MACHINE HAVING AT LEAST ONE CUTTING WIRE, AND METHOD FOR MACHINING AN OPTICAL GLASS THEREOF - Google Patents

Abstract

The machine for machining (10) optical glass (12), comprising: - a system (15) for machining optical glass (12), - a support (14) for optical glass (12), and - a positioning mechanism (16) of the support (14) relative to the machining system (15). The machining system (15) includes a cutting system (47) having at least one cutting wire (55) configured to cut the optical glass (12).

Description

DESCRIPTION

Optical glass machining machine comprising at least one cutting wire, and method for machining an associated optical glass

The present invention relates to a machining machine, of the type comprising:

- an optical glass machining system,

- a support for optical glass, and

- a mechanism for positioning the support relative to the machining system.

Such machines are known and commonly used to machine blanks for optical glass, generally having circular shapes with a diameter of the order of 60 mm to 80 mm, in final shapes, similar to the shape of the circles of the frame. glasses in which the machined lenses will be assembled. On these known machines, the machining system generally consists of grinding wheels and / or cutters.

However, these known machines are not entirely satisfactory. In fact, during the machining of the optical glass blank by a process using grinding wheels, the machining is done by removing successive material around the periphery of the blank until the final shape is obtained. desired. The same is true for certain machines using cutters. This machining process generates many drawbacks:

- this type of machining process generates a large volume of dust and shavings which are difficult to channel with a view to their evacuation and clog the machine;

- the removal around the optical blank of all this material takes time and lengthens the machining process;

- the volume of material to be machined decreases the life of the cutting tools.

In order to solve these problems, machines have been developed using small diameter cutters, configured so that the cutter enters the blank of the optical glass up to a tangent position of the desired final shape, before following the outline of the desired final shape. The volume of machined material is reduced, since it only corresponds to the path of the cutter around the desired final shape.

However, these machines only allow the processing of plastics and other resins. In no case does it allow the processing of mineral glass. Finally, the cutting process with a cutter generates a significant noise due to the cutting of the materials and the necessarily high speed of rotation of the cutters. This noise level is not acceptable in the environment of an optical store.

Objects of the invention are therefore:

- to allow with a single tool to machine the roughing of lenses of all types of materials, including plastic, resin but also mineral glass;

- to reduce the volume of shavings and dust generated by the machining process, in order to facilitate the evacuation and treatment, a posteriori, of this waste;

- reduce the power of the motorization of the cutting tools;

- to reduce the machining time of the lenses;

- extend the life of the cutting tools; and

- reduce the noise level during machining.

To this end, the subject of the invention is a machining machine of the aforementioned type, in which the machining system comprises a cutting system comprising at least one cutting wire configured to cut optical glass.

According to particular embodiments of the invention, the machining machine also comprises one or more of the following characteristics, taken alone or according to any technically possible combination (s):

- The cutting wire is elongated in a direction of elongation, and the machining system comprises a drive device for moving the cutting wire relative to the optical glass in said direction of elongation;

- The support comprises a motor for rotating the optical glass around a longitudinal axis;

- the direction of elongation is parallel to the longitudinal axis;

- The drive device comprises two flywheels arranged apart from one another, the cutting wire being wound around each of said flywheels;

- the speed of movement of the cutting wire according to its direction of elongation is between 10 m / s and 100 m / s;

- the cutting system comprises a tensioner capable of regulating the tension of the cutting wire;

- the tensioner is able to measure the tension of the cutting wire, and the machining machine comprises a control unit able to control the positioning mechanism as a function of the tension of the cutting wire;

- the cutting system comprises a cooling system for the cutting wire, capable of ejecting an air jet on the cutting wire;

- The cutting system comprises a liquid distributor capable of applying a liquid to the cutting wire;

- The machining system comprises at least one grinding wheel and / or at least one milling cutter capable of removing material from the optical glass;

- The positioning mechanism comprises a first mechanism for moving the optical glass relative to the cutting wire in a plane orthogonal to the direction of elongation of the cutting wire to bring the optical glass closer to and away from the cutting wire;

- The first movement mechanism is able to move the optical glass in the orthogonal plane at a forward speed which is a function of the tension of the cutting wire.

The invention also relates to a method of machining an optical glass, comprising a step of cutting the optical glass by a cutting wire.

According to a particular embodiment of the invention, the machining process also includes the following characteristic:

- cutting the optical glass comprises moving the cutting wire in a direction of elongation of said cutting wire.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the appended drawing, which represents a front view of a machining machine according to the invention .

Figure 1 illustrates a machining machine 10 intended to machine an optical glass 12, in particular to modify the shape of its periphery.

The machining machine 10 comprises a frame 13, a support 14 for the optical glass 12, a machining system 15 for the optical glass 12, and a mechanism 16 for positioning the support 14 relative to the machining system 15.

The support 14 comprises a carriage 17 pivotally mounted on the frame 13, provided with two half-shafts 19A, 19B adapted to grip the optical glass 12, and a motor 21 for rotating the optical glass 12.

The carriage 17 is articulated relative to the frame 13, by a rear longitudinal edge 24, around an axis B-B ’of substantially horizontal tilting.

The two half-shafts 19A and 19B are mounted along a front longitudinal edge 26 of the carriage 17. These half-shafts 19A and 19B extend along a longitudinal axis A-A 'substantially horizontal parallel to the axis B-B '.

The half-shafts 19A and 19B are provided with respective free ends 27A, 27B arranged facing one another, adapted to grip the optical glass 12.

The drive motor 21 is capable of rotating the half-shafts 19A and 19B in rotation around the longitudinal axis A-A ’. This rotation of the half-shafts 19A, 19B causes the optical glass 12 to rotate about the longitudinal axis A-A ’.

The machining system 15 comprises a cutting system 47 and a drive device 49.

Here, the machining system 15 also comprises grinding wheels 51 and a milling cutter 53. As a variant, the machining system 15 comprises a single grinding wheel 51 and / or a plurality of milling cutters 53, or neither grinding wheel nor milling cutter.

The cutting system 47 comprises a cutting wire 55 and a tensioner 57. Here, the cutting system 47 also includes a system 59 for cooling the cutting wire 55 and a liquid distributor 61.

The cutting wire 55 is configured to cut the optical glass 12.

To this end, the cutting wire 55 comprises a rectilinear segment 62 adapted to come into contact with the optical glass 12. This rectilinear segment 62 is elongated in a direction of elongation which will be designated hereinafter “direction of elongation of the cutting wire 55 ", although some portions of cutting wire 55 do not necessarily extend in said direction of elongation.

In the embodiment shown, the direction of elongation is parallel to the longitudinal axis A-A ’.

The cutting wire 55 has a diameter of between 0.2 mm and 3 mm. Thus, the friction between the cutting wire 55 and the optical glass 12 is relatively low, which makes it possible to reduce the power of the drive motor and to reduce the noise caused by cutting.

Advantageously, the cutting wire 55 is coated with an abrasive coating. The abrasive coating is for example made of diamond.

The tensioner 57 is able to regulate the tension of the cutting wire 55. More specifically, the tensioner 57 is able to bear against the cutting wire 55 and to tension the cutting wire 55 so that the rectilinear segment 62 of the wire cutting 55 remains rectilinear despite the force exerted on the latter by the optical glass 12 during the cutting of the optical glass 12.

Preferably, the tensioner 57 is also able to measure the tension of the cutting wire 55.

The cooling system 59 is capable of ejecting an air jet on the cutting wire 55 in order to cool it. Advantageously, the air jet is also able to blow the machining waste away from the optical glass 12 and / or the cutting wire 55.

The liquid distributor 61 is able to apply a liquid to the cutting wire 55. This liquid is able to cool and lubricate the cutting wire 55.

The drive device 49 is configured to move the cutting wire 55 relative to the optical glass 12 in the direction of elongation of the cutting wire 55.

According to the embodiment shown in the Figures, the drive device 49 comprises two flywheels 63 arranged apart from one another. It also includes at least one flywheel drive motor 63 (not shown). The cutting wire 55 is wound around each of the flywheels 63 and is driven in translation along its direction of elongation.

The rectilinear segment 62 is interposed between the flywheels 63.

The flywheels 63 are advantageously covered with a friction layer where the cutting wire 55 comes into contact with the flywheels 63 to increase the friction between the cutting wire 55 and the flywheels 63. The friction layer is for example made of polyurethane .

The flywheels 63 drive the cutting wire 55 in displacement in its direction of elongation at a displacement speed of between 10 m / s and 100 m / s.

Preferably, the drive device 49 comprises a single motor which drives the two flywheels 63 in rotation.

Alternatively, the drive device 49 includes two drive motors each driving a respective flywheel 63. These drive motors are then independent or speed controlled relative to each other.

The grinding wheels 51 and the cutters 53 are capable of removing material from the optical glass 12. The cutters 53 are further able to mill holes in the optical glass 12. They are used in a conventional manner known to those skilled in the art.

The positioning mechanism 16 is configured to position the support 14 (and, through this, the optical glass 12) relative to the machining system 15.

The positioning mechanism 16 comprises a first displacement mechanism 66, making it possible to pivot the carriage 17 around the axis B-B ’.

The positioning mechanism 16 also includes a second longitudinal translation mechanism 68, able to move the support 14, and consequently the optical glass 12, relative to the frame 13 along the longitudinal axis AA ’.

The first movement mechanism 66 allows the optical glass 12 to be brought closer and / or further away from the machining system 15. It is able to move the optical glass 12 in an orthogonal plane l-l 'at a forward speed which is a function of the tension of the cutting wire 55. This makes it possible to avoid deformation of the rectilinear segment 62 of the cutting wire 55 under the effect of the pressure applied to it by the optical glass 12 during the cutting of said glass 12.

The plane l-l 'is substantially perpendicular to the axis B-B'.

The second longitudinal translation mechanism 68 makes it possible to position the optical glass 12 at a location of the rectilinear segment 62 of the cutting wire 55.

Advantageously, the second longitudinal translation mechanism 68 is able to bring the point of contact between the optical glass 12 and the cutting wire 55 as close as possible to a flywheel 63 to limit the deformation of the cutting wire 55 under the effect of the pressure applied to it by the optical glass 12 during the cutting of said glass 12.

The second longitudinal translation mechanism 68 also makes it possible to position the optical glass 12 on one of the grinding wheels 51 of the machining system 15.

The second longitudinal translation mechanism 68 also makes it possible to move the optical glass 12 relative to one of the cutters 53 in order to drill a hole in the optical glass 12.

Here, the machining machine 10 further comprises a control unit 80. In the example shown, this control unit 80 is configured to control the flywheels 63, the motor 21 for rotating, the first movement mechanism 66 , and the longitudinal translation mechanism 68. As a variant, the control unit 80 is configured to control only part of the flywheels 63, motor 21 for rotating, first movement mechanism 66, and longitudinal translation mechanism 68 .

A method of cutting the optical glass 12 with the machining machine 10 will now be described.

First, the optical glass 12 is disposed between the free ends 27A, 27B and is held in the carriage 17.

The control unit 80 controls the first movement mechanism 66 so that it pivots the carriage 17 around the axis B-B 'so as to lower the carriage 17 and, thus, the optical glass 12 relative to the wire. cutting 55 until the periphery of the optical glass 12 comes into contact with the cutting wire 55.

Optionally, the longitudinal translation mechanism 68 simultaneously moves the carriage 17 so as to adjust the position of the optical glass 12 along the longitudinal axis A-A ’.

Then, the control unit 80 controls the start of the flywheels 63. The flywheels 63 drive the cutting wire 55 in its direction of elongation so that it rubs against the optical glass 12. This friction causes abrasion optical glass 12.

The motor 21 for rotating and the first movement mechanism 66 are then controlled by the control unit 80 so that they cooperate to allow the cutting wire 55 to move around the optical glass 12 along the desired contour, this relative displacement, associated with the abrasion of the optical glass 12, causing the cutting of the optical glass 12 to the desired shape. More precisely :

- The motor 21 for rotating causes the optical glass 12 to rotate about the longitudinal axis A-A ’;

- The first movement mechanism 66 raises and / or lowers the carriage 17 so as to modify the height of the optical glass 12. This gives a speed of advance to the optical glass 12 in the orthogonal plane l-l ’.

In particular, the control unit 80 controls the first movement mechanism 66 and the motor 21 so that the speed of advance of the optical glass 12 relative to the cutting wire 55 in the longitudinal plane l-l 'is a function of the tension of the cutting wire 55.

These joint movements allow the cutting wire 55 to cut the optical glass 12 to any desired shape.

Advantageously, the flywheels 63 are fixed in translation relative to the frame 13 so that, during the machining process, the cutting wire 55 only moves in its direction of elongation. This makes it possible in particular to simplify the design of the machining system 15, in particular by eliminating the need to have a system for moving the flywheels 63 relative to the frame 13.

When the cutting of the optical glass 12 is finished, the flywheels 63 are stopped.

The optical glass 12 is then machined, in a known manner, by means of the grinding wheels 51 and the cutter 53, so as to produce the finishes of the optical glass 12.

Finally, the first movement mechanism 66 moves the optical glass 12 away from the machining system 15, and the first and second half-shafts 19A,

19B move apart to allow the machined optical glass 12 to be extracted from the machine 10.

Thanks to the invention described above, it is now possible to machine an optical glass to any final shape, with a simple machining process. In addition, the quantity of chips produced by machining is considerably reduced compared to machining by the grinding wheel and / or the cutter. Finally, the machining time is considerably reduced.

In addition, thanks to the relatively narrow diameter of the cutting wire 55 compared to the diameter of a milling cutter, the machining process of the invention significantly reduces noise.

Claims (15)

1. Machining machine (10) for optical glass (12), comprising: - a machining system (15) for the optical glass (12), a support (14) for the optical glass (12), and - a positioning mechanism (16) of the support (14) relative to the machining system (15), characterized in that the machining system (15) comprises a cutting system (47) comprising at least one cutting wire (55) configured to cut the optical glass (12). 2. Machining machine (10) according to claim 1, wherein the cutting wire (55) is elongated in an elongation direction, and the machining system (15) comprises a drive device (49) for moving the cutting wire (55) relative to the optical glass (12) in said direction of elongation. 3. Machining machine (10) according to any one of the preceding claims, in which the support (14) comprises a motor (21) for rotating the optical glass (12) around a longitudinal axis (A- AT'). 4. Machining machine (10) according to claims 2 and 3 taken together, in which the direction of elongation is parallel to the longitudinal axis (A-A ’). 5. Machining machine (10) according to any one of the preceding claims, in which the drive device (49) comprises two flywheels (63) arranged away from one another, the wire of cutout (55) being wrapped around each of said flywheels (63). 6. Machining machine (10) according to any one of claims 2 to 5, wherein the speed of movement of the cutting wire (55) in its direction of elongation is between 10 m / s and 100 m / s. 7. Machining machine (10) according to any one of the preceding claims, in which the cutting system (47) comprises a tensioner (57) capable of regulating the tension of the cutting wire (55). 8. Machining machine (10) according to claim 7, in which the tensioner (57) is able to measure the tension of the cutting wire (55), and the machining machine (10) comprises a control unit ( 80) capable of controlling the positioning mechanism (16) as a function of the tension of the cutting wire (55). 9. Machining machine (10) according to any one of the preceding claims, in which the cutting system (47) comprises a system of 10 cooling (59) of the cutting wire (55), capable of ejecting an air jet on the cutting wire (55). 10. Machining machine (10) according to any one of the preceding claims, in which the cutting system (47) comprises a liquid distributor (61) capable of applying a liquid to the cutting wire (55). 11. Machining machine (10) according to any one of the preceding claims, in which the machining system (15) comprises at least one grinding wheel (51) and / or at least one milling cutter (53) capable of removing from the material to the optical glass (12). 12. Machining machine (10) according to any one of the preceding claims, in which the positioning mechanism (16) comprises a first movement mechanism (66) of the optical glass (12) relative to the cutting wire (55) in a plane orthogonal (l-l ') to the direction of elongation of the cutting wire (55) to bring the optical glass (12) and the distance away from the cutting wire (55). 13. Machining machine (10) according to claim 12, wherein the first movement mechanism (66) is adapted to move the optical glass (12) in the orthogonal plane (l-l ') at a forward speed which is a function of the tension of the cutting wire (55). 14. Method of machining an optical glass (12), comprising a step of cutting the optical glass (12) by a cutting wire (55). 15. The machining method according to claim 14, wherein the cutting of the optical glass (12) comprises moving the cutting wire (55) in a direction of elongation of said cutting wire (55).