Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B9/00—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor
  • B24B9/02—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground
  • B24B9/06—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain
  • B24B9/08—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass
  • B24B9/14—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass of optical work, e.g. lenses, prisms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B27/00—Other grinding machines or devices
  • B24B27/0076—Other grinding machines or devices grinding machines comprising two or more grinding tools

Definitions

• the present invention relates to a machine for grinding optical glasses of the type described in the preamble of claim 1.
• the main object of the invention is to remedy these drawbacks, that is to say to have a machine which makes it possible to simply perform the counter-beveling, the creasing and / or the drilling of optical glasses with a quality of 'constant operation regardless of the curvature of the lens, and which is compact.
• the invention relates to a grinding machine of the aforementioned type, characterized in that the control means are adapted to retract the tool holder shaft by controlling said angle of inclination.
• Another object of the invention is to obtain a grinding machine of the aforementioned type, the structure of which is simplified.
• the machine of the aforementioned type comprises means for relative displacement of the tool-holder shaft relative to the lens support in translation along the third axis when the tool is in position active, and said relative displacement means comprise means of relative translation of the tool-holder shaft relative to the second axis in a first direction, parallel to the second axis, means of pseudo-translation of the lens support relative to the second axis in a second direction perpendicular to the second axis, and means for synchronizing said means of translation and pseudo-translation.
• FIG. 1 is a partial perspective view of three-quarters upper of the relevant parts of a grinding machine according to the invention
• FIG. 2 is a partial sectional view along the line II-II in Figure 1;
• - Figure 3 is a perspective view taken along arrow III of Figure 1 of a detail of the grinding machine according to the invention, with the tool holder assembly in the retracted position;
• FIG. 4 is a partial sectional view along line IV-IV of Figure 1 of the grinding machine according to the invention during a drilling operation;
• FIG. 5 is a view of a detail of Figure 4.
• the grinding machine shown in Figures 1 to 5 is intended to produce a beveled and counter-beveled optical glass, as well as creasing and drilling operations from a generally circular lens blank.
• This grinding machine comprises a frame 11, a grinding assembly 13, a lens support 15, a tool holder assembly 17 and a control unit 19.
• the grinding assembly 13 comprises a train of grinding wheels 21 rotatably mounted about a first horizontal axis AA in a grinding wheel support 22 and driven in rotation by a grinding motor (not shown).
• the train of grinding wheels 21 is composed of several grinding wheels 21 A to 21 D juxtaposed.
• the grinding wheels are associated with a type of glass for grinding and at different stages of the grinding process: a grinding wheel 21A for roughing mineral glasses, a grinding wheel 21 B for roughing synthetic glasses, a finishing grinding wheel with beveling 21 C provided a circular groove 23, and a polishing wheel 21 D with beveling.
• This train of grinding wheels 21 can optionally be equipped with finishing or polishing grinding wheels without bevelling.
• This train of grinding wheels 21 is mounted integrally on a grinding wheel shaft 25, itself mounted free in rotation in the support 22 around the first axis A-A '.
• the lower part 27 of the grinding wheel support 22 is slidably mounted in an axial direction parallel to the first axis AA ′ on a sliding bar 29. Means (not shown) enable the grinding assembly 13 to move in translation in this axial direction by sliding the grinding wheel support 22 along the sliding bar 29.
• the lens support 15 comprises a carriage 31 pivotally mounted on the frame 11 and provided with two half-shafts 33A and 33B suitable for gripping the lens blank 35, a motor 37 for driving the lens blank 35 in rotation. , and means 39 for radial positioning of the carriage 31 relative to the first axis AA ′.
• the carriage is articulated by a longitudinal edge 41 around a tilting shaft 43 arranged parallel to the first axis AA ′.
• the two half-shafts 33A and 33B are mounted along the other longitudinal edge 45 of the carriage 31. These half-shafts 33A and 33B are arranged along a second horizontal axis BB 'which, during grinding, is parallel to the first axis A-A '. Furthermore, these half-shafts 33A and 33B are provided with free ends 47A and 47B facing each other, adapted to grip the lens blank 35.
• the drive motor 37 of the lens blank 35 rotates around the second axis BB 'the half-shaft 33B and the half-shaft 33A by a transmission mechanism (not shown).
• the radial positioning means 39 of the carriage 31 relative to the first axis A-A ' comprise a drive mechanism 51 and a guide rod or button 53.
• the drive mechanism 51 comprises an endless screw 55 for driving in cooperation with a nut 57.
• the screw 55 is rotatably mounted on the frame 11 and arranged in a radial direction perpendicular to the axial direction. In the example illustrated in Figure 2, the drive screw 55 is vertical.
• This drive screw 55 is rotated by a motor 59 secured to the frame 11.
• the carriage 31 is provided with feelers 61 of the lens blank 35, connected to the control unit 19.
• the tool holder assembly 17 comprises a support 71 provided with a projecting link arm 73, a tool holder shaft 75, a motor 77 for driving the rotation of the tool holder shaft 75, and means 79 for actuating the tool holder shaft 75.
• the support 71 is of generally cylindrical shape. It is rotatably mounted on the grinding wheel support 22 around a horizontal pivot axis DD ', perpendicular to the first axis A-A'.
• the tool-holder shaft 75 is rotatably mounted around a third axis CC at the free end of the link arm 73.
• the tool-holder shaft 75 remains in the vertical plane passing through the first axis A-A '.
• This shaft 75 carries a grinding wheel 81 for bevelling, a grinding wheel 83, and a drill bit 85 for drilling.
• the counter-beveling grinding wheel 81 has a diameter much smaller than that of the grinding wheels 21 A to 21 D of the wheel train. As illustrated in FIG. 5, this counter-beveling grinding wheel has on the outside a cylindrical median surface 87, framed by two frustoconical surfaces 89 and 91 which converge away from this surface. As illustrated in FIG. 5, it is a surface 89 having a relatively small apex half-angle, for example of the order of 35 °, and an opposite surface 91 having a apex half-angle relatively large, for example 55 °.
• the creasing wheel 83 comprises a single cylindrical central surface 92 of small width. In the example illustrated in Figure 5, the width of the cylindrical median surface is between 0.5 and 1.6 mm.
• the drilling forest 85 is mounted at the free end of the tool-holder shaft 75 and is aligned along the third axis C-C.
• the rotary drive motor 77 of the tool-holder shaft 75 is connected to this shaft 75 by transmission means comprising in particular a pulley 93 and a belt 95 ( Figure 1).
• the actuation means 79 of the tool-holder shaft 75 comprise (FIG. 1) an actuation motor 101, the output shaft 103 of which is provided at its end with a worm screw 105. This worm screw 105 cooperates with a tangent toothed wheel secured to the support 71.
• These actuating means 79 rotate the support 71 around the pivot axis on an angular displacement of at least 30 °, and preferably 180 °. Consequently, during this rotational movement, the angle formed between the third axis CC and the first axis AA 'or the second axis BB' varies at least between 0 and 30 ° and preferably between 0 and 180 °.
• the control unit 19 makes it possible to control, on the one hand, the movement of the grinding wheel support 22 in the axial direction and, on the other hand, the movement of the carriage 31 around the articulation shaft 43. Thus, this unit control 19 coordinates the relative movement of the lens support relative to the train of grinding wheels.
• this control unit is provided with synchronization means (not shown) making it possible to simultaneously control the axial movement of the grinding wheel support 22 and the movement of the carriage 31 around the articulation shaft, according to a predefined control law .
• synchronization means (not shown) making it possible to simultaneously control the axial movement of the grinding wheel support 22 and the movement of the carriage 31 around the articulation shaft, according to a predefined control law .
• the support 71 is oriented so that the arm 73 and the tool-holder shaft 75 are in a retracted position under the wheel train 21.
• the space situated above grinding wheels 21 A to 21 D is completely free.
• the blank 35 is wedged between the two ends 47A and 47B of the half-shafts 33A and 33B by an adapter suitably positioned on the blank.
• an adapter suitably positioned on the blank.
• the control unit 19 controls the axial displacement means of the grinding wheel support 22 and the radial displacement means 39 of the carriage 31 to position the lens blank 35 in contact with the roughing grinding wheel 21A.
• the motor for rotating 37 of the lens blank 35 relative to the second axis B-B ' is then actuated to rotate this blank 35 around this second axis B-B'.
• the distance between the first axis AA 'and the second axis BB' is adjusted according to the angular position of the blank 35 around the second axis B-B ', depending on the shape of the mount. glasses on which the lens will be fitted after treatment. In the same way, the lens is then brought to the finishing wheel with beveling 21 C.
• the blank then has its final outline.
• a drilling operation is then carried out.
• the grinding wheel support 22 is positioned at the end of the axial stroke.
• This limit switch corresponds to a position of the grinding wheel support 22 at the extreme right of FIG. 1.
• the carriage 31 is moved away from the grinding wheel train 21 by displacement of the guide rod 53 upwards until a radial limit switch.
• the actuating motor 101 of the tool holder assembly 17 is then activated.
• the rotation of the output shaft 103 of this motor 101 rotates the worm 105 around an axis parallel to the first axis AA ′.
• This endless screw 105 cooperates with the toothed wheel provided on the support 71.
• the support 71 is then driven in rotation about its pivot axis D-D '.
• This rotational movement of the support 71 causes the pivoting of the tool-holder shaft 75 about the pivot axis DD 'in the vertical plane passing through the axis A-A', from the retracted position shown in Figure 3 , located under the wheel train, in an active position shown in Figure 4, located above the wheel train.
• the control unit 19 determines the angle formed by the tangent to the external or internal surface of the lens blank 35 at the point of drilling of this blank 35 and the direction perpendicular to the second axis BB 'which passes through this drilling point. This angle is designated by g in FIG. 5.
• the angle ⁇ depends on the curvature of the lens blank 35.
• the actuating motor 101 of the tool holder assembly 17 is deactivated when the angle formed by the third axis C-C and the second axis B- B 'is equal to this angle g.
• the means of axial displacement of the support 22 and the means of radial displacement 51 of the carriage 31 are then controlled to bring the end of the forest 85 into contact with the drilling point ( Figure 4).
• the forest 85 is then perpendicular to the external surface of the lens blank 35, whatever the curvature of this blank.
• the rotary drive motor 77 of the tool holder shaft 75 is then activated.
• the means of axial displacement of the support and the means of radial displacement 39 of the carriage 31 are then controlled by the synchronization means of the control unit 19 to move in translation the tool-holder shaft 75 along the third axis CC while maintaining the inclination of this third axis CC relative to the second axis BB 'constant and equal to ⁇ , during the entire drilling operation. More precisely, during drilling, the support 22 moves to the left and the carriage 31 moves downwards so that the drilling point moves exactly along the axis CC.
• the angle formed by the third axis CC and the second axis BB ' is controlled before a counter-bevel operation so that the angle of attack between the surface of the counter-bevel grinding wheel 81 and the edge quick to machine the lens blank 35 is equal to a predetermined value regardless of the curvature of this blank.
• the angle of inclination of the third axis CC relative to the second axis BB ' is controlled before a creasing operation so that the median plane P of the creasing wheel 85 is for example parallel to the tangent to the convex surface of the lens blank at the sharp edge, or parallel to a direction intermediate between the tangents of the convex and concave surfaces.

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• 2003
  • 2003-03-27 FR FR0303792A patent/FR2852878B1/fr not_active Expired - Fee Related
• 2004
  • 2004-03-25 WO PCT/FR2004/000754 patent/WO2004087374A1/fr active Application Filing
  • 2004-03-25 US US10/549,897 patent/US7281967B2/en active Active
  • 2004-03-25 CN CNB2004800081291A patent/CN100519070C/zh not_active Expired - Lifetime
  • 2004-03-25 EP EP04742359A patent/EP1606079B1/de not_active Expired - Lifetime

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