DEVICE FOR POLISHING AN OPTICAL LENS OR AN OPTICAL MIRROR AND METHOD FOR POLISHING AN OPTICAL LENS OR AN OPTICAL MIRROR

Abstract

A device and a method for polishing an optical lens or an optical mirror use a polishing tool and a workpiece holding ring for accommodating the optical lens or the optical mirror. The workpiece holding ring is arranged above the tool in a vertical direction, and the device has three axes, which are movable during the polishing process, for moving the workpiece holding ring and the polishing tool.

Claims

1. A device for polishing an optical lens or an optical mirror using a polishing tool and using a workpiece holding ring for accommodating the optical lens or the optical mirror, wherein the workpiece holding ring is arranged above the tool in a vertical direction, wherein the device (30) comprises three axes (X.sub.1, Z.sub.1, B.sub.1), which are movable during the polishing process, for moving the workpiece holding ring (11) and the polishing tool (23).

2. The device of claim 1, wherein the workpiece holding ring (11) having the two movable axes (X.sub.1, Z.sub.1) and the polishing tool (23) having the one movable axis (B.sub.1) are designed to be movable in an interpolating manner during the polishing process, and wherein a center point of the workpiece holding ring (11) is arranged vertically above a center point of the polishing tool (24) during the polishing process.

3. The device of claim 1, wherein the workpiece holding ring (11) is arranged so as to rest on the polishing tool (23) by gravity.

4. The device of claim 1, wherein the optical lens (19) or the optical mirror is arranged so as to rest on the polishing tool (23) by gravity.

5. The device of claim 1, wherein the workpiece holding ring (11) is mounted for rotation about a longitudinal axis (L.sub.W).

6. The device of claim 1, wherein at least one smoothing device (20) for a polishing pad (24) of the polishing tool (23) is arranged on a support surface (34) of the workpiece holding ring (11) arranged in the direction of the polishing tool (23).

7. The device of claim 1, wherein the workpiece holding ring (11) is designed to be drivable at a first rotational speed (n.sub.2) and the polishing tool (23) is designed to be drivable at a second rotational speed (n.sub.1), and wherein the polishing process is executable at two rotational speeds (n.sub.1, n.sub.2) deviating from one another, wherein a direction of rotation of the workpiece holding ring (11) and a direction of rotation of the polishing tool (23) are synchronous.

8. The device of claim 1, wherein workpiece holding ring (11) is exchangeable for a second holding ring (29) comprising a driveable tool spindle (29) for machining a surface of the polishing tool (23).

9. The device of claim 8, wherein four movable axes (X.sub.1, Z.sub.1, B.sub.1, C.sub.1) are designed to be movable during the process of machining the surface of the polishing tool (23).

10. The device of claim 1, wherein, using the device (30), spherical optical lenses (19) or spherical optical mirrors or planar optical lenses or planar optical mirrors are polishable.

11. A method for polishing an optical lens or an optical mirror using a polishing tool for polishing the optical lens or the optical mirror, in which the optical lens or the optical mirror is arranged in a workpiece holding ring, wherein the workpiece holding ring is arranged above the polishing tool in a vertical direction, wherein the polishing process is carried out using three movable axes (X.sub.1, Z.sub.1, B.sub.1) for moving the workpiece holding ring (11) and the polishing tool (23).

12. The method of claim 11, wherein the workpiece holding ring (11) having the two movable axes (X.sub.1, Z.sub.1) and the polishing tool (23) having the one movable axis (B.sub.1) are moved in an interpolating manner during the polishing process such that a center point of the workpiece holding ring (11) is arranged vertically above a center point of the polishing tool (23) during the polishing process.

13. The method of claim 11, wherein the optical lens (19) or the optical mirror rests on the polishing tool (23) by gravity.

14. The method of claim 11, wherein the workpiece holding ring (11) rests on the polishing tool (23) by gravity.

15. The method of claim 11, wherein the workpiece holding ring (11) is driven so as to be rotatable about a longitudinal axis (L.sub.W) during the polishing process, and wherein the optical lens (19) arranged in the workpiece holding ring (11) or the optical mirror arranged in the workpiece holding ring (11) rotates due to friction with the workpiece holding ring (11) about a longitudinal axis (L.sub.L) of the optical lens (19) or of the optical mirror.

16. The method of claim 11, wherein at least one smoothing device (20), which is arranged on a support surface (34) of the workpiece holding ring (11) arranged in the direction of the polishing tool (23), smooths the polishing pad (24) during the polishing process.

17. The method of claim 11, wherein the workpiece holding ring (11) is driven at a first rotational speed (n.sub.2) and the polishing tool (23) is driven at a second rotational speed (n.sub.1), and wherein the polishing process (23) is carried out at two rotational speeds (n.sub.1, n.sub.2) deviating from one another, wherein a direction of rotation of the workpiece holding ring (11) and a direction of rotation of the polishing tool (23) are synchronous.

18. A method for machining a polishing pad of a polishing tool comprising a device (30) having the features according to claim 8, wherein the machining process for machining the surface of the polishing tool (23) is carried out using an interpolating movement with four movable axes (X.sub.1, Z.sub.1, B.sub.1, C.sub.1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0115] In the drawings,

[0116] FIG. 1 shows a device according to the invention in the sectional view;

[0117] FIG. 2 shows the mounting of the workpiece holding ring in the longitudinal sectional view;

[0118] FIG. 3 shows a representation of the movement of the tool; and

[0119] FIG. 4 shows the device according to the invention used to machine the tool, in the longitudinal sectional view.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0120] FIG. 1 shows the device 30 with a base unit 1. The base unit 1 consists preferably of granite plates, which are joined. The base unit 1 can also consist of other materials.

[0121] A tool spindle 5 is arranged in the base unit 1 so as to be swivelable about an axis B.sub.1. The tool spindle 5 is swivelable and controllable by 90 about the axis B.sub.1.

[0122] The tool spindle 5 is a rotation axis C.sub.1, which has an entrainment device 31 on the upper end, the rotation axis C.sub.1 is positionable and controllable.

[0123] A polishing tool 23 is arranged on the upper end of the tool spindle 5. A polishing pad 24 is applied on the polishing tool 23. An optical lens 19 is arranged perpendicularly on the polishing tool 23. An optical mirror can also be arranged.

[0124] The optical lens 19 is pressed against the polishing pad 24 by its own weight.

[0125] In order to ensure the vertical position of the optical lens 19 at any point in time, the position of the optical lens is supported by a workpiece holding ring 11 and a holding arm 12.

[0126] The workpiece holding ring 11 is in turn positioned by catching rollers 22, 32 (see FIG. 2) precisely centrally relative to the workpiece holding ring 11.

[0127] Advantageously, the workpiece holding ring 11 is supported by three rollers. Two rollers are designed as catching rollers 22, 32, the third roller is designed as a drive roller 21.

[0128] The workpiece holding ring 11 rotates about a longitudinal axis L.sub.W. The optical lens 19 rotates about a longitudinal axis L.sub.L.

[0129] The workpiece holding ring 11 can rotate in the holding arm 12 without friction. The workpiece holding ring 11 has no contact with the holding arm 12. The workpiece holding ring 11 has contact only with the rollers 21, 32, 23.

[0130] As is apparent in FIG. 3, a gap 33 is provided between the workpiece holding ring 11 and the holding arm 12, such that the workpiece holding ring 11 and the holding arm 12 are arranged contactlessly with respect to one another.

[0131] The drive of the workpiece holding ring 11 is shown in FIG. 2. In order to generate, or to control, the rotational movement and, as a result, a relative speed between the polishing tool 23 and the workpiece holding ring 11, a drive roller 21 is provided, which is driven by a drive motor 25 (FIG. 1).

[0132] Displacement axes X.sub.1, Z.sub.1, B.sub.1 and C.sub.1 are shown in FIGS. 1 through 4.

[0133] X.sub.1 and Z.sub.1 are axes of a Cartesian coordinate system.

[0134] The polishing tool 23 is swiveled about the axis B.sub.1.

[0135] C.sub.1 is a vertical axis parallel to the Z.sub.1 axis. The polishing tool 23 rotates about the axis C.sub.1, as is shown in FIG. 4, when the polishing tool 23 is machined.

[0136] As is shown in FIG. 1, the polishing tool 23 rotates at a rotational speed n.sub.1. The optical lens 19 rotates at a rotational speed n.sub.2.

[0137] The rotational speeds n.sub.1, n.sub.2 are different rotational speeds. The direction of rotation of the optical lens 19 and of the tool 23 is synchronous.

[0138] The workpiece holding ring 11 is set into a rotational movement, as is shown in FIG. 2. The rotational movement of the optical lens 19 is generated by an entrainment effect at an edge between the optical lens 19 and the workpiece holding ring 11. This arrangement is a friction drive.

[0139] In order to position the workpiece holding ring 11 on the center point of the tool 23, the workpiece holding ring 11 lies with its underside on the polishing tool 23 under its own weight.

[0140] As is shown in FIGS. 2 and 3, glass parts 20 are arranged on a support surface 34 of the workpiece holding ring 11, which glass parts have the function of a smoothing device for the polishing pad 23. The glass parts 20 are provided, prior to the actual polishing operation, on an external device having the radius of the workpiece to be machined, i.e., of the optical lens 19 or of an optical mirror. A contact surface of the support surface 34 is designed in the shape of a ring. This contact surface is used to position the workpiece holding ring 11 in relation to the polishing tool 23. The contact surface is used to continuously smooth the polishing pad 24. As a result, the function of a continuous polishing process is created.

[0141] The holding arm 11 is fixed to a carriage 18 and can be controlled and positioned over the axis Z.sub.1 using a motor drive 17. The carriage 18, which is displaceable in the Z.sub.1 direction, is connected via a linear bearing system (not shown) to a carriage 16, which is displaceable in the X.sub.1 direction. The carriage 16, which is displaceable in the X.sub.1 direction, is connected to the base unit via a linear bearing system 14. The carriage 16, which is displaceable in the X.sub.1 direction, is positioned and controlled in the X direction in a motor-driven manner using a drive 15.

[0142] The swivel axis B.sub.1 is positioned and controlled via a motor drive 10. A holding arm 9, which accommodates the tool spindle 5, is fastened on the opposite side of the motor drive 10 by means of a cardanically compensating counter bearing 2, 3, 4. As a result, a high rigidity of the B.sub.1 axis position is ensured.

[0143] The base unit is fixedly arranged on a base stand 7. As a result, a desired operating height of the device 30 is achieved. In order to cover the work space, a cover 26 is arranged over the work region of the tool 23. The cover 26 can be moved up and down in the direction of a Z.sub.2 axis.

[0144] A rotation action 8 is represented in FIG. 1. If the tool spindle 5 needs to be lubricated from below, because lubrication from the outside is no longer sufficient, lubrication is carried out by the rotation action 8.

[0145] The base stand 7 has a bore 6. Excess polishing agent can drain through this bore 6.

[0146] The carriage 16, which is displaceable in the X.sub.1 direction, is arranged on a transverse carriage 13.

[0147] FIG. 2 shows, as described above, the mounting of the holding ring 11. The holding ring 11 is held by two catching rollers 22, 32 and is driven by the drive roller 21, which rotates at a rotational speed n.sub.3. The glass parts 20 are arranged on a support surface 34 of the workpiece holding ring 11.

[0148] The glass parts 20 can be designed, for example, as lenses having a spherical surface formed in the direction of the polishing tool 23.

[0149] The catching rollers 22, 32 are mounted with ball bearings and have rubber tires.

[0150] The optical lens 19, which rotates at a rotational speed n.sub.2, is also shown in FIG. 2. The optical lens 19 rotates since it intermittently rests with its edge on the workpiece holding ring 11 and, due to friction, an entrainment effect arises.

[0151] FIG. 3 shows the optical lens 19, which rests on the polishing pad 24. The workpiece holding ring 11 is driven by the drive roller 21, which is set into rotation by a drive motor 25. The drive roller 21 rotates at the rotational speed n.sub.3.

[0152] The method according to the invention is carried out, as is shown in FIG. 3. The workpiece holding ring 11 is placed in the holding arm 12. The workpiece holding ring 11 moves cardanically aligned on the polishing tool 23, which is fastened to the tool spindle 5.

[0153] The optical lens 19 is placed into the workpiece holding ring 11 and rests, under its own weight, cardanically on the polishing tool 23 with the polishing pad 24.

[0154] After the polishing process starts, the tool spindle 5 begins to rotate at a rotational speed n.sub.1. At the same time, the workpiece holding ring 11 is driven at the rotational speed n.sub.2 by the drive 25 and the roller 21 synchronously with the rotational movement of the polishing tool 23 at the rotational speed n.sub.1. The rotational speed ratio n.sub.1 to n.sub.2 is mathematically ascertained using the formula:

[00002]$n_2=n_1.Math.\cos {}_1$ [0155] with n.sub.1 first rotational speed, [0156] n.sub.2=second rotational speed, [0157] .sub.1=swivel angle.

[0158] The rotational speed ratio is set by a CNC controller.

[0159] Once the rotational movement of the tool spindle 5 and the workpiece holding ring 11 begins, a swiveling about the axis B.sub.1 at the angle is started. This swiveling movement is combined with the movement of the X.sub.1 carriage 16 and of the Z.sub.1 carriage 18. This triaxial, interpolating movement is carried out such that the optical lens 19 rests exclusively vertically on the polishing pad 24 during the polishing process. The polishing tool 23 swivels through under the workpiece surface of the optical lens 19.

[0160] The swivel movement is a part of the calculation for the surface of the polishing pad 24, which is arranged on the polishing tool 23.

[0161] The angle is composed of the difference between .sub.1 and .sub.2. .sub.1 and .sub.2 are swivel angles. They are also referred to as pitch angles.

[0162] The polishing pad has a radius R.sub.1 and the polishing tool has a radius R.sub.2.

[0163] In FIG. 3, OW.sub.W designates the opening angle of the tool and OW.sub.L designates the opening angle of the optical lens 19. The opening angles are the overall aperture of the tool or the overall aperture of the optical lens 19.

[0164] The manufacture of the polishing pad 24 is shown in FIG. 4.

[0165] The device 30 can also be used to manufacture the polishing pad.

[0166] The same parts are labeled using the same reference numbers.

[0167] In order to manufacture the polishing pad 24 such that the polishing process does not result in a change to the radius of the polishing tool 23, the surface of the polishing pad 24 is machined, by means of a separate method, such that a mathematically predetermined surface arises.

[0168] This surface of the polishing pad 24, which is related to so-called synchro-speed method, is generated by means of a milling tool 35.

[0169] In order to be able to carry out the operation of machining the polishing pad 24 on the device 30, the workpiece holding ring 11 is removed from the holding arm 12 and replaced by a second holding ring 27. A high-speed tool spindle 29 is arranged in the second holding ring 27. The milling tool 35, for example, in the form of an end-milling cutter, is arranged on the lower end of this tool spindle 29. The milling tool 35 can have a spherical cutting edge. The second holding ring 27 is fixedly attached to the holding arm 12 using holding pieces 28.

[0170] Then, the process of milling the surface of the polishing tool 23 begins in the polishing pad 24. The machining is a four-axis process. The axes C.sub.1/X.sub.1/Z.sub.1/B.sub.1 interpolate during this machining.

[0171] The machining process has two tasks: [0172] a) manufacturing a polishing pad 24 extending precisely with respect to the axis of rotation of the polishing tool 23 [0173] b) manufacturing a surface of the polishing pad 24 that is suitable for holding the radius of the polishing tool 23 stable during the actual polishing process.

[0174] Once the tool manufacturing process has ended, the second holding ring 27 with the tool spindle 29 is removed again.

[0175] Then, the workpiece holding ring 11, with the optical lens 19 or the optical mirror, is re-installed into the holding arm 12.

[0176] Then, the polishing process can begin.

[0177] The milling tool 35 rotates at a rotational speed n.sub.4.

[0178] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

NUMBERED REFERENCES

[0179] 1 base unit [0180] 2 cardanically compensating counter bearing [0181] 3 cardanically compensating counter bearing [0182] 4 cardanically compensating counter bearing [0183] 5 tool spindle [0184] 6 bore as discharge for polishing agent [0185] 7 base stand [0186] 8 rotation action [0187] 9 holding arm [0188] 10 motor drive [0189] 11 workpiece holding ring [0190] 12 holding arm [0191] 13 transverse carriage [0192] 14 linear bearing system [0193] 15 drive for x-direction [0194] 16 carriage movable in X.sub.1 direction [0195] 17 motor drive [0196] 18 carriage movable in Z.sub.1 direction [0197] 19 optical lens [0198] 20 glass parts [0199] 21 drive roller [0200] 22 catching roller [0201] 23 polishing tool [0202] 24 polishing pad [0203] 25 drive motor [0204] 26 cover [0205] 27 second holding ring [0206] 28 holding pieces [0207] 29 tool spindle [0208] 30 device [0209] 31 entrainment device [0210] 32 catching roller [0211] 33 gap [0212] 34 support surface [0213] 35 milling tool [0214] Z.sub.1 axis [0215] Z.sub.2 axis [0216] X.sub.1 axis [0217] B.sub.1 axis [0218] C.sub.1 axis [0219] L.sub.W longitudinal axis of workpiece holding ring [0220] L.sub.L longitudinal axis of optical lens or optical mirror [0221] n.sub.1 rotational speed [0222] n.sub.2 rotational speed [0223] n.sub.3 rotational speed [0224] n.sub.4 rotational speed [0225] R.sub.1 radius [0226] R.sub.2 radius [0227] .sub.1 angle [0228] .sub.2 angle [0229] OW.sub.W opening angle of polishing tool [0230] OW.sub.L opening angle of lens [0231] angular difference