Device for polishing an optical lens or an optical mirror and method for polishing an optical lens or an optical mirror

Abstract

The invention relates to a device and a method for polishing an optical lens or an optical mirror with a polishing tool and with a workpiece holder ring for receiving the optical lens or optical mirror, wherein the workpiece holder ring is arranged in a vertical direction above the tool, wherein the device has three axes (X1, Z1, Bl) movable during the polishing process for moving the workpiece holder ring and the polishing tool. (Fig. 1).

Description

[0001] The invention relates to a device for polishing an optical lens or an optical mirror and a method for polishing an optical lens or an optical mirror.

[0002] For the sake of linguistic simplicity, the following text refers to lenses. However, this also always refers to optical mirrors with an imaging function.

[0003] Optical lenses are manufactured in practice from transparent materials through several grinding processes or other machining methods. These materials can be mineral glass or suitable plastics.

[0004] In practice, optical lenses are manufactured from blanks in several work steps. Grinding is followed by polishing, in which the surface is smoothed.

[0005] It is known in practice to manufacture the base body of the polishing tool from a solid material. The working area of ​​the base body has a shape that roughly corresponds to the negative impression of the surface of the lens to be polished. This area of ​​the polishing tool is coated with the aforementioned polishing foil or with polishing pitch, and this is then precisely dressed using a dressing tool. After the dressing process, the surface of the polishing coating corresponds very closely to the negative impression of the optical lens. Such polishing tools are called forming tools. However, polishing tools are also known whose surface in the working area consists of a material that possesses the properties of a polishing foil, thus eliminating the need for an additional polishing foil.

[0006] As is common practice, the polishing tool is attached to a tool spindle of a polishing machine, which sets it in rotation. The lens to be polished is located in a workpiece carrier, also called a lens holder, which is itself connected to a workpiece spindle and also rotates. The necessary drive for this is located in the workpiece spindle. The tool spindle and the workpiece spindle of the polishing machine can usually be moved along several axes. Furthermore, one of the two spindles can be tilted so that the geometric axes of the tool and lens form an angle with each other and intersect at the center of the radius of the spherical lens surface to be machined. The tool spindle and the workpiece spindle rotate synchronously. They rotate at different speeds. This method is also known as the synchrospeed method.

[0007] The state of the art (DE 100 44 872 A1) includes a method for polishing optical lenses or mirrors with imaging properties using a polishing machine.

[0008] According to this state of the art, the optical lens is mounted in a lens holder, which in turn is spring-mounted and therefore has axial movement. The polishing pressure between the polishing tool and the lens is applied by springs, after these have been pre-tensioned by feed movements of at least one of the machine spindles. The lens is held firmly in the lens holder by applying a vacuum to its rear surface against the lens support. The lens support is first adapted to the rear surface of the lens by dressing in the polishing machine.

[0009] Polishing involves the use of specialized polishing tools, either made of a plastic suitable for polishing, such as Novotex or Pertinax, or metal tools coated with a polishing material. This polishing material can be, for example, a foamed polyurethane film with a thickness of 0.5 to 1.3 mm, depending on the tool size, or a polishing pitch several millimeters thick. The polishing suspension typically consists of a rare-earth polishing compound dissolved in water, such as Opaline or Cerox (cerium oxides). The particle size of the polishing compound is typically between 0.5 µm and 3.5 µm. However, other polishing compounds can also be used, such as aluminum oxide (Al₂O₃) or iron oxides.However, very fine diamond liquids with a grain size in the range of 0.5 to 3.0 µm can also be used.

[0010] The polishing process has both a mechanical removal function and chemical and thermal effects.

[0011] For precise imaging with a ground lens, the glass surface must be treated by polishing. This further reduces the surface roughness and eliminates any remaining deviations from the required sphere radius or the desired sphere shape.

[0012] Polishing is achieved through a sliding relative movement between the surface of the workpiece and a polishing tool, which is designed to hold a polishing compound carrier. This carrier, in conjunction with a polishing compound, enables the removal of material, thus smoothing or refining the workpiece surface.

[0013] Very high demands are placed on the polishing compound carrier and the polishing compound itself. For example, the polishing compound carrier must be malleable to accommodate the required workpiece radius. Furthermore, it must bond well to the tool holder and must be free of impurities that could damage the glass surface. As already mentioned, elastomeric films made of foamed polyurethane are well-suited, as their good mechanical and chemical properties largely meet these requirements. Polishing pitches and other wax-like coatings are also suitable.

[0014] The requirements for a polishing compound are not directly attributable to measurable quantities, so the selection and mixture of the polishing compound are essentially based on empirical data. Suspensions of finely ground oxides of trivalent and tetravalent metals are predominantly used, although these depend heavily on the material being processed. Often, a tool determines the shape of a workpiece during machining. However, this is not as true when polishing glass materials as it is, for example, in machining metals. Particularly when polishing glass lenses, the polishing compound carrier adapts to the surface of the workpiece due to wear, so that even after processing only a few areas, the tool radius has changed. The desired correction of the lens surface quickly falls outside the specified tolerances.This makes it necessary to adjust the polishing medium carrier to the required ball radius at regular intervals during the polishing process, i.e., to adapt it so that the shape accuracy and grip of the polishing tool are maintained.

[0015] The dressing of a polishing tool is often performed outside the polishing machine on specialized dressing machines. These are, for example, lever-operated machines with diamond pellet-coated flat tools, the settings of which can only be determined empirically. Furthermore, the polishing correction tool must be ground in using a specially manufactured tool before the actual correction of the polishing tool can take place. Often, several adjustments to the polishing tool and, if necessary, the grinding tool are required, making this process extremely laborious and very expensive. When dressing with flat tools, a separate polishing correction tool must be manufactured for each radius.

[0016] The prior art (EP 0 727 280 A1) includes a device and a method for polishing spherical lens surfaces. This prior art device is designed as a three-spindle machine. It is a CNC machine tool with a swiveling unit on one axis and a rotating tool spindle for holding a polishing tool. A second feed drive, mounted at a fixed distance, supports a rotatably mounted workpiece spindle for holding a lens and a tool spindle, rotatably mounted parallel to it, for holding a dressing tool, such as a cup tool. Relative swiveling between the polishing tool and the lens is possible. This prior art is known as the "Synchrospeed method."

[0017] In this process, the lenses are held by a workpiece chuck. This chuck consists of a guide ring, a base body, and a diaphragm that is pressurized with compressed air via the workpiece spindle to force the lens into place. Opposite the workpiece chuck with the inserted lens, on the tool spindle side, is a tool that, according to the prior art, is approximately twice the diameter of the lens. This tool has a coating of polishing foil or is made of a material suitable for performing optical polishing.

[0018] The polishing tool is also firmly connected to the machine's tool spindle via a mechanical clamping system. To ensure the polishing tool has the exact radius of the lens being machined, a second spindle, equipped with a dressing tool, is located parallel to the workpiece spindle on the three-axis CNC machine. This dressing tool, as is common practice, is a ring-shaped cup tool, which is also firmly connected to the dressing spindle via a mechanical system.

[0019] This state-of-the-art CNC machine has the disadvantage of being very expensive. Furthermore, the lens mount must be machined on a separate CNC-controlled grinding machine.

[0020] Particularly fine surfaces of optical materials, such as optical glass or crystalline materials, can be achieved by using polishing pitch as a tool coating. However, polishing pitch is thermoplastic, and the polishing time is significantly longer than when using polyurethane (thermoset) film as a tool coating. Polishing with pitch produces a lower surface roughness. A shorter processing time is achieved when using polyurethane film as a polishing coating.

[0021] Since the production of spherical components must be particularly economical, PU film is currently predominantly used in practice for polishing optical materials.

[0022] However, if a very fine surface quality is required, a second process stage involves polishing with a tool coated with polishing pitch.

[0023] In practice, tools with polishing foils are used whose surface coating is calculated in such a way that no change in the tool's shape occurs during processing, even if the foil wears down. This so-called Synchrospeed method is currently state of the art in polishing with polishing foils.

[0024] Another component of this Synchrospeed process is the constant relative speed between the tool and the workpiece.

[0025] However, to date these methods could only be implemented when polishing with polishing pads made of polishing film.

[0026] The major advantage of using polishing pitch lies in the fact that optical surfaces with the highest form qualities (up to λ / 100 and better) but also with the lowest surface roughness (1 to 2 angstroms) can be produced. Polishing with polishing foil is about ten times worse.

[0027] Since qualities in the range of λ / 50 to λ / 100 are now required in the spherical area as well as in the roughness range of 2 to 3 Angstroms and better, very expensive and lengthy correction processes usually have to be used after spherical pre-polishing with foil.

[0028] This is a huge problem, especially with large lenses, for example from 100 mm diameter up to 2 m diameter, because the correction techniques are extremely expensive and also extremely slow.

[0029] For industrial sectors that require large quantities of large spherical optics, very high investments are necessary.

[0030] As the demand for large optics with very high accuracy and very low roughness grows, for example in laser and space optics, the state-of-the-art methods and equipment for manufacturing these large lenses and mirrors are becoming uneconomical. This is especially true for new optical materials such as silicon carbide (SiC) components, where state-of-the-art methods are too expensive.

[0031] The technical problem underlying the invention is to provide a device and a method for polishing an optical lens or an optical mirror, with which a polishing process can be carried out economically and with which polishing foils or polishing pitch can be used equally.

[0032] This technical problem is solved by a device having the features according to claim 1 and by a method having the features according to claim 11.

[0033] The device according to the invention for polishing an optical lens or an optical mirror with a polishing tool and with a workpiece holder ring for receiving the optical lens or optical mirror, wherein the workpiece holder ring is arranged in a vertical direction above the tool, is characterized in that the device has three axes movable during the polishing process for moving the workpiece holder ring and the polishing tool.

[0034] In the device according to the invention, a three-axis polishing process is carried out.

[0035] It is advantageous to perform a three-axis interpolating machining process around an axis center point of the polishing tool.

[0036] "Movable" means, firstly, movement in one direction of a Cartesian coordinate system. Secondly, it means that a pivoting movement around an axis can be performed.

[0037] The polishing tool is advantageously designed in a semi-spherical shape and has a center point.

[0038] Advantageously, the workpiece holder ring is moved in the X and Z directions, where X and Z are coordinates of a Cartesian coordinate system and Z represents the vertical direction.

[0039] Furthermore, the polishing tool is advantageously pivoted about a swivel axis. This swiveling movement is combined with the movement of the movable X-axis and the movable Z-axis. This three-axis interpolating movement is performed in such a way that the workpiece, i.e., the optical lens or optical mirror, always rests vertically on the tool surface, i.e., on the polishing tool with the polishing coating.

[0040] The polishing tool advantageously pivots beneath the workpiece surface of the optical mirror or optical lens.

[0041] The pivoting movement is part of the calculation for the surface of the polishing pad applied to the polishing tool.

[0042] The device according to the invention makes it possible to process particularly large lenses or large mirrors, for example with a diameter of more than 100 mm and up to, for example, 2 m, economically and cost-effectively.

[0043] According to an advantageous embodiment of the invention, it is provided that the workpiece holding ring with the two movable axes and the polishing tool with the one movable axis are designed to be movable interpolatingly during the polishing process, and that a center point of the workpiece holding ring is arranged vertically above a center point of the polishing tool during the polishing process.

[0044] The workpiece holder ring runs advantageously in a cardan-like alignment on the polishing tool.

[0045] The workpiece holder ring is advantageously moved in the X and Z directions. The polishing tool is advantageously pivoted about an axis. The three movable axes of the polishing tool and the workpiece holder ring are designed to move interpolatingly, so that a center point of the workpiece holder ring is positioned vertically above a center point of the polishing tool during the polishing process.

[0046] With the device according to the invention, the workpiece holding ring is positioned on the center point of the tool.

[0047] The movable axis of the polishing tool should be understood in the sense that the polishing tool is pivoted around the axis. In this case, the movement is a pivoting motion.

[0048] According to a further advantageous embodiment of the invention, the workpiece holding ring is arranged to be in contact with the polishing tool by means of gravity.

[0049] This embodiment has the advantage that the workpiece holder ring is positioned on the center point of the tool when the workpiece holder ring rests on the polishing tool with its underside bearing its own weight.

[0050] According to a further advantageous embodiment of the invention, the optical lens or optical mirror is arranged to be in contact with the polishing tool by means of gravity.

[0051] This design ensures that the optical lens or mirror rests gimbal-like on the polishing tool under its own weight. The workpiece rests gimbal-like on the polishing surface.

[0052] According to a further advantageous embodiment of the invention, the workpiece holding ring is rotatably mounted about a longitudinal axis.

[0053] The workpiece holder ring is driven by a motor. The workpiece holder ring rotates around its longitudinal axis.

[0054] A frictional drive is generated at the edge between the optical lens or mirror and the workpiece holder ring.

[0055] This friction drive allows the optical lens or optical mirror to rotate at a predetermined rotational speed and yet only come into contact with the polishing tool due to gravity.

[0056] Another advantageous embodiment of the device according to the invention provides that at least one smoothing device for a polishing coating of the polishing tool is arranged on a support surface of the workpiece holder ring arranged in the direction of the workpiece.

[0057] This embodiment has the advantage that this contact surface, which is provided by the support surface and the smoothing device arranged on the support surface, allows the workpiece holder ring to be positioned relative to the polishing tool.

[0058] This contact surface serves to continuously smooth the polishing layer. This creates the function of the continuous polishing process.

[0059] The at least one smoothing device advantageously consists of glass parts arranged on the contact surface of the workpiece holder ring. These glass parts can, for example, be in the form of lenses. Before the actual polishing operation, these glass lenses can be provided with the radius of the workpiece to be processed, i.e., the optical lens or optical mirror, on an external device.

[0060] The smoothing device, for example of the glass parts, advantageously results in a continuous smoothing of the polishing coating.

[0061] The contact surface of the workpiece holder ring is advantageously designed in the form of a ring. This ring serves to position the workpiece holder ring relative to the polishing tool.

[0062] The glass lenses of the smoothing device are advantageously arranged with their spherical surface facing the polishing tool. With a flat surface, the glass lenses can be arranged on the contact surface of the workpiece holder ring.

[0063] According to a further advantageous embodiment of the invention, it is provided that the workpiece holding ring is designed to be driven at a first rotational speed and the polishing tool at a second rotational speed, and that the polishing process can be carried out at two different rotational speeds, wherein one direction of rotation of the workpiece holding ring and one direction of rotation of the polishing tool are synchronous.

[0064] This means that the workpiece holder ring, and therefore also the optical lens or mirror, which also rotates around its longitudinal axis due to the friction drive, has a first rotational speed, and that the polishing tool has a second rotational speed, which differs from the first. The direction of rotation of the workpiece holder ring, and therefore of the optical lens or mirror, and the direction of rotation of the polishing tool are synchronous.

[0065] This ensures that the polishing process is carried out effectively and reliably.

[0066] According to a further advantageous embodiment of the invention, the workpiece holding ring is interchangeable with a holding ring with a driveable tool spindle for machining a surface of the polishing tool.

[0067] In order to produce the polishing coating of the polishing tool in such a way that no changes in the radius of the polishing tool occur during the polishing process, the surface of the polishing coating is processed by means of a separate method with the same device according to the invention in such a way that a mathematically predetermined surface is created.

[0068] For machining the polishing tool, it is advantageous to replace the workpiece holder ring with a holder ring that has a driven tool spindle. A surface finishing tool, for example a finger cutter, is mounted on the tool spindle. The finger cutter can, for example, have a spherical cutting edge.

[0069] The milling process of the polishing tool surface can then be carried out in the polishing coating.

[0070] According to a particularly preferred embodiment of the invention, four movable axes are provided during the machining process of the surface of the polishing tool. This means that, in addition to the two axes in the X and Z directions and the movable, i.e., pivotable, axis B1 for the polishing tool, a fourth axis C1 is added.

[0071] This is a rotary axis mounted on a tool spindle. The rotary axis is positionable and adjustable.

[0072] With the device according to the invention, it is advantageously possible to polish spherical optical lenses or spherical optical mirrors or planar optical lenses or planar optical mirrors.

[0073] The device according to the invention thus has the advantage that it is universally applicable and can therefore save costs.

[0074] The inventive method for polishing an optical lens or an optical mirror with 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 holder ring, wherein the workpiece holder ring is arranged in a vertical direction above the polishing tool, is characterized in that the polishing process is carried out with three movable axes for moving the workpiece holder ring and the polishing tool.

[0075] The workpiece holder ring is moved along two axes, namely the X-axis and the Z-axis. The X-axis and the Z-axis are axes of a Cartesian coordinate system. The Z-axis is the vertical axis.

[0076] The polishing tool is moved by means of a further axis. The polishing tool does not perform a linear movement, but rather a pivoting movement around the third axis.

[0077] This three-axis method of the workpiece holder ring and the polishing tool ensures that the polishing process is carried out in such a way that the optical lens or mirror is always vertically oriented. The optical lens or mirror always rests vertically on the polishing tool, i.e., on the tool's surface. The polishing tool pivots beneath the surface of the optical lens or mirror.

[0078] According to a further advantageous embodiment of the method according to the invention, it is provided that the workpiece holder ring with two movable axes and the polishing tool with one movable axis are moved interpolatingly during the polishing process, such that a center point of the workpiece holder ring is arranged vertically above a center point of the polishing tool during the polishing process.

[0079] This embodiment allows for high-precision machining of the surface of the optical lens or optical mirror.

[0080] This three-axis interpolating movement is carried out in such a way that the optical lens or optical mirror always rests vertically on the polishing tool, i.e., on the polishing surface.

[0081] According to a further advantageous embodiment of the invention, the optical lens or optical mirror rests on the polishing tool by means of gravity. This means that the optical lens or optical mirror does not need to be pressed down separately or held in a separate holding device.

[0082] This allows the optical lens or optical mirror to rest gimbal-like on the polishing tool.

[0083] Furthermore, no separate, technically complex holding device is required for the optical lens or optical mirror.

[0084] According to a further advantageous embodiment, the workpiece holding ring rests on the polishing tool by means of gravity.

[0085] This embodiment has the advantage that the workpiece holder ring is positioned at the center of the polishing tool. The workpiece holder ring advantageously rests on the polishing tool with its underside, i.e., with its bearing surface, bearing its own weight.

[0086] According to a further advantageous embodiment of the invention, it is provided that the workpiece holding ring is rotatably driven about a longitudinal axis during the polishing process and that the optical lens or optical mirror arranged in the workpiece holding ring rotates about a longitudinal axis of the optical lens or optical mirror by friction with the workpiece holding ring.

[0087] To perform a polishing process, the optical lens or mirror must rotate around its longitudinal axis. Since the optical lens or mirror rests favorably on the polishing tool due to gravity and rotates at a different speed—that is, the speed of the polishing tool differs from the speed of the optical lens or mirror—friction between the lens edge and the workpiece holder ring sets the optical lens or mirror into rotation.

[0088] According to a further advantageous embodiment of the invention, it is provided that at least one smoothing device, which is arranged on a support surface of the workpiece holder ring arranged in the direction of the workpiece, smooths the polishing coating during the polishing process.

[0089] The workpiece holder ring advantageously rests against the polishing tool due to gravity. At least one smoothing device is advantageously arranged on the contact surface of the workpiece holder ring. This smoothing device rests against the polishing surface of the polishing tool during the polishing process.

[0090] Advantageously, the smoothing device is constructed from glass parts, preferably lens-shaped glass parts. These glass parts are advantageously positioned on an external device with the radius of the workpiece to be processed prior to the actual polishing operation. This ensures continuous smoothing of the polishing surface during the polishing process.

[0091] Another advantageous embodiment of the method according to the invention provides that the workpiece holder ring is driven with a first rotational speed and the polishing tool with a second rotational speed, and that the polishing process is carried out with two different rotational speeds, wherein one direction of rotation of the workpiece holder ring and one direction of rotation of the polishing tool are synchronous.

[0092] After the polishing process according to the invention has started, the polishing tool begins to rotate at a first speed. n 1. To rotate. At the same time, the workpiece holding ring is driven synchronously with the direction of rotation. n 1 with the rotational speed n 2 driven. The speed ratio n 1 to n 2 is determined mathematically and advantageously set by a CNC control.

[0093] Advantageously, the ratio of the rotational speeds is determined as follows: n 2 = n 1 ⋅ cos α 1 with n 1. First rotational speed, n 2 = second rotational speed, α l = swivel angle.

[0094] According to a further advantageous embodiment, a method for machining a polishing coating of a polishing tool is specified with a device which has a driveable tool spindle instead of the workpiece holder ring, which is characterized in that the machining process for machining the surface of the polishing tool is carried out with an interpolating movement with four movable axes.

[0095] These are the axes X1, Z1, B1, and C1. X1 and Z1 are the axes of the Cartesian coordinate system, and the Z1 axis is a vertical axis. The B1 axis runs parallel to the X-axis. The polishing tool can be pivoted about the B1 axis.

[0096] The C1 axis runs parallel to the Z1 axis.

[0097] With the device and method according to the invention, the contact force of the optical lens or optical mirror against the polishing tool is advantageously generated by gravity.

[0098] The device and method according to the invention are suitable for both planar machining and spherical machining of optical lenses or mirrors.

[0099] Furthermore, the device according to the invention can be modified by replacing the workpiece holder ring with a machining tool so that the surface of the polishing tool can be machined on the device according to the invention, resulting in a polishing tool that retains its shape without an additional polishing correction plate. The device can also be used with tools coated with polishing pitch.

[0100] In the method according to the invention, after the rotary movement of a tool spindle and the workpiece holder ring has begun, a pivoting of axis B1 at an angle Δα is advantageously initiated. This pivoting movement is combined with a movement of the slide that is movable in the X-direction and the slide that is movable in the Z-direction. This three-axis interpolating movement is carried out such that the optical lens or optical mirror always rests vertically on the polishing surface. The polishing tool pivots under a workpiece surface of the optical lens or optical mirror. This pivoting movement is part of the calculation for the surface of the polishing surface applied to the polishing tool.

[0101] In order to produce the polishing coating in such a way that the polishing process does not cause any change in the radius of the tool, the surface of the polishing coating is treated using a separate process to create a mathematically predetermined surface.

[0102] According to an advantageous embodiment of the invention, this surface treatment of the polishing layer, which is related to the so-called Synchrospeed process, is produced by means of a milling tool.

[0103] To perform this operation on the device according to the invention, the workpiece holder ring is removed and replaced with another holder ring. A high-speed tool spindle is advantageously arranged in the second holder ring. A milling cutter, for example a finger cutter, is advantageously arranged at the lower end of this tool spindle. The finger cutter can have a spherical cutting edge.

[0104] The milling process of the polishing tool surface is now carried out in the polishing coating. This machining process is four-axis. The axes C1, X1, Z1, and B1 interpolate during this machining operation.

[0105] The machining process has the task of producing a surface precisely aligned with the first axis of rotation. n 1 running polishing tool surface.

[0106] The machining process aims to produce a polishing tool surface suitable for the

[0107] To keep the radius of the polishing tool stable during the actual polishing process.

[0108] Polishing pitch can be used in the inventive method and device. It is also possible to use a polishing foil.

[0109] For example, a pitch can be used which is mixed with plastic or wood particles, or with a polishing agent or copper particles or the like.

[0110] After the tool manufacturing process is complete, the second retaining ring is removed along with the tool spindle. The workpiece retaining ring is then reinstalled, and the optical lens or mirror can be positioned within it.

[0111] Further features and advantages of the invention will become apparent from the accompanying drawings, in which a device according to the invention is shown only by way of example, without limiting the invention to these embodiments. The drawings show: Fig. 1 a device according to the invention in section; Fig. 2 the bearing of the workpiece holder ring in longitudinal section; Fig. 3 a representation of the movement of the tool; Fig. 4 the device according to the invention for use in machining the tool in longitudinal section.

[0112] Fig. 1 Figure 30 shows the device with a base unit 1. The base unit 1 preferably consists of granite slabs that are joined together. The base unit 1 can also be made of other materials.

[0113] In the base unit 1, a tool spindle 5 is arranged so as to be pivotable about an axis B 1. The tool spindle 5 can be pivoted and adjusted about the axis B 1 by ± 90°.

[0114] The tool spindle 5 is a rotary axis C 1 which has a drive device 31 at its upper end; the rotary axis C 1 is positionable and controllable.

[0115] A polishing tool 23 is arranged at the upper end of the tool spindle 5. A polishing coating 24 is applied to the polishing tool 23. An optical lens is arranged perpendicular to the polishing tool 23. An optical mirror may also be arranged.

[0116] The optical lens 19 is pressed against the polishing pad 24 by its own weight.

[0117] To ensure the vertical position of the optical lens 19 at all times, the position of the optical lens is supported by a workpiece holding ring 11 and a holding arm 12.

[0118] The workpiece holding ring 11 is in turn positioned exactly in the middle of the workpiece holding ring 11 by means of catch rollers 22, 32.

[0119] Advantageously, the workpiece holding ring 11 is supported by three rollers. Two rollers are designed as catch rollers 22, 23, the third roller is designed as a drive roller 21.

[0120] The workpiece holder ring 11 rotates about a longitudinal axis LW. The optical lens 19 rotates about a longitudinal axis LL.

[0121] The workpiece holding ring 11 can rotate freely within the holding arm 12. The workpiece holding ring 11 has no contact with the holding arm 12. The workpiece holding ring 11 only has contact with the rollers 21, 22, 23.

[0122] As in Fig. 3 As can be seen, a gap 33 is provided between the workpiece holding ring 11 and the holding arm 12, so that the workpiece holding ring 11 and the holding arm 12 are arranged without contact with each other.

[0123] In Fig. 2 The drive of the workpiece holder ring 11 is shown. To generate or control the rotary motion and thus a relative speed between the polishing tool 23 and the workpiece holder ring 11, a drive roller 21 is provided, which is driven by a drive motor 25 ( Fig. 1 ) is powered.

[0124] In the Fig. 1 bis 4 The traverse axes X l , Z l , B l and C 1 < are shown.

[0125] X1 and Z1 are axes of a Cartesian coordinate system.

[0126] The polishing tool 23 is pivoted around axis B 1.

[0127] C1 is a perpendicular axis parallel to the Z1 axis. It rotates around the axis C1, as shown in Fig. 4 The polishing tool 23 is shown when the polishing tool 23 is being processed.

[0128] As in Fig. 1 As shown, the polishing tool 23 rotates at a rotational speed n1. The optical lens 19 rotates at a rotational speed n2.

[0129] The rotational speeds n1 and n2 are different. The direction of rotation of the optical lens 19 and the tool 23 is synchronous.

[0130] The workpiece holding ring 11 is, as in Fig. 2 The optical lens 19 is set into a rotational movement. This rotational movement is generated by a drive effect at an edge between the optical lens 19 and the workpiece holder ring 11. This is a friction drive.

[0131] To position the workpiece holder ring 11 on the center point of the tool 23, the workpiece holder ring 11 rests on the polishing tool 23 with its underside under its own weight.

[0132] As in Fig. 3 As shown, glass parts 20 are arranged on a support surface 34 of the workpiece holder ring 11. These glass parts function as a smoothing device for the polishing coating 23. Before the actual polishing operation, the glass parts 20 are mounted on an external device with the radius of the workpiece to be processed, i.e., the optical lens 19 or an optical mirror. A contact surface of the support surface 34 is designed in the form of a ring. This contact surface serves to position the workpiece holder ring 11 relative to the polishing tool 23. The contact surface serves to continuously smooth the polishing coating 24. This creates the function of a continuous polishing process.

[0133] The holding arm 11 is rigidly connected to a carriage 18 and can be controlled and positioned via the Z1 axis by a motor drive 17. The carriage 18, which is movable in the Z1 direction, is connected via a linear bearing system (not shown) to a carriage 16, which is movable in the X1 direction. The carriage 16, which is movable in the X1 direction, is connected to the base unit via a linear bearing system 14. The carriage 16, which is movable in the X1 direction, is positioned and controlled in the X direction by a motor via a drive 15.

[0134] The swivel axis B1 is positioned and controlled by a motor drive 10. On the opposite side of the motor drive 10, a holding arm 9, which accommodates the workpiece spindle 5, is attached by a cardanically compensating counter bearing 2, 3, 4. This ensures high rigidity of the B1 axis position.

[0135] The base unit is fixedly mounted on a base frame 7. This creates the desired operating height of the device 30. To cover a work area, a cover 26 is positioned over the working area of ​​the tool 23. The cover 26 can be moved up and down in the direction of a Z 2 axis.

[0136] In Fig. 1 A rotary feedthrough 8 is shown. If lubrication of the tool spindle 5 from below is necessary because external lubrication is no longer sufficient, lubrication is provided by the rotary feedthrough 8.

[0137] The base frame 7 has a bore 6. Excess polishing compound can drain away through this bore 6.

[0138] The carriage 16, which can be moved in the X 1 direction, is arranged on a transverse carriage 13.

[0139] Fig. 2 Figure 1 shows, as already explained, the bearing arrangement of the retaining ring 11. The retaining ring 11 is held by two catch rollers 22, 32 and driven by the drive roller 21, which rotates at a speed n 3. The glass parts 20 are arranged on a support surface 34 of the workpiece retaining ring 11.

[0140] The glass parts 20 can, for example, be designed as lenses with a spherical surface formed in the direction of the polishing tool 23.

[0141] The catch rollers 22, 32 are mounted with ball bearings and have rubber tires.

[0142] In Fig. 2 Furthermore, the optical lens 19 is shown, which rotates at a speed n 2. The optical lens 19 rotates because its edge temporarily rests against the workpiece holder ring 11, and friction creates a driving effect.

[0143] Fig. 3 Figure 1 shows the optical lens 19, which rests on the polishing surface 24. The workpiece holding ring 11 is driven by the drive roller 21, which is set in rotation by a drive motor 25. The drive roller 21 rotates at speed n3.

[0144] The inventive method is carried out as described in Fig. 3 The workpiece holder ring 11 is inserted into the holding arm 12. The workpiece holder ring 11 runs in a cardan-aligned manner on the polishing tool 23, which is attached to the tool spindle 5.

[0145] The optical lens 19 is inserted into the workpiece holder ring 11 and rests gimbal-mounted on the polishing tool 23 with the polishing pad 24 by its own weight.

[0146] After the polishing process starts, the workpiece spindle 5 begins to rotate at a speed nl. Simultaneously, the workpiece holder ring 11 is driven by the drive 25 and the roller 21 synchronously with the rotational movement of the polishing tool 23 at speed nl and speed n2. The speed ratio nl to n2 is mathematically determined using the formula: n 2 = n 1 ⋅ cos α 1 with n 1. First rotational speed, n 2 = second rotational speed, α 1 = swivel angle.

[0147] The speed ratio is set by a CNC control.

[0148] After the rotary motion of the tool spindle 5 and the workpiece holder ring 11 begins, a pivoting motion about axis B1 at angle Δα is initiated. This pivoting motion is combined with the movement of the X1 slide 16 and the Z1 slide 18. This three-axis interpolating motion is performed such that the optical lens 19 rests exclusively vertically on the polishing surface 24 during the polishing process. The polishing tool 23 pivots beneath the workpiece surface of the optical lens 19.

[0149] The pivoting movement is part of the calculation for the surface of the polishing pad 24, which is arranged on the polishing tool 23.

[0150] The angle Δα is the difference between α1 and α2. α1 and α2 are swivel angles, also called adjustment angles.

[0151] The polishing pad has a radius R l.

[0152] In Fig. 3 OWw denotes the opening angle of the tool and OWL denotes the opening angle of the optical lens 19. These opening angles represent the total aperture of the tool or the total aperture of the optical lens 19.

[0153] In Fig. 4 The production of the polishing layer 24 is shown.

[0154] The polishing coating can also be produced with the device 30.

[0155] Identical parts are assigned the same reference numbers.

[0156] In order to produce the polishing coating 24 in such a way that the polishing process does not cause any change in the radius of the polishing tool 23, the surface of the polishing coating 24 is processed by means of a separate process so that a mathematically predetermined surface is created.

[0157] This surface of the polishing layer 24, which is related to the so-called Synchrospeed process, is produced by means of a milling tool 35.

[0158] To perform the machining operation of the polishing surface 24 on the device 30, the workpiece holder ring 11 is removed from the holding arm 12 and replaced with a second holder ring 27. A high-speed tool spindle 29 is arranged in the second holder ring 27. At the lower end of this tool spindle 29, the milling tool 35, for example in the form of a finger cutter, is arranged. The milling tool 35 can have a spherical cutting edge. The second holder ring 27 is firmly attached to the holding arm 12 by means of retaining pieces 28.

[0159] The milling process of the surface of the polishing tool 23 in the polishing pad 24 now begins. The machining is a four-axis process. The axes C1 / X1 / Z1 / B1 interpolate during this machining operation.

[0160] The processing process has two tasks: a) the production of a polishing pad 24 that runs exactly to the axis of rotation of the polishing tool 23 b) the production of a surface of the polishing pad 24 that is suitable to keep the radius of the polishing tool 23 stable during the actual polishing process.

[0161] After completion of the tool manufacturing process, the second retaining ring 27 is removed again with the tool spindle 29.

[0162] The workpiece holding ring 11 with the optical lens 19 or the optical mirror is then reinstalled in the holding arm 12.

[0163] The polishing process can then begin.

[0164] The milling tool 30 rotates at a speed n 4 . Reference figures

[0165] 1 Base unit 2 Cardan-assisted counter bearing 3 Cardan-assisted counter bearing 4 Cardan-assisted counter bearing 5 Tool spindle 6 Bore as drain for polishing compound 7 Base frame 8 Rotary feedthrough 9 Holding arm 10 Motor drive 11 Workpiece holder ring 12 Holding arm 13 Cross slide 14 Linear bearing system 15 Drive for X-direction 16 Slide movable in X1 direction 17 Motor drive 18 Slide movable in Z1 direction 19 Optical lens 20 Glass parts 21 Drive roller 22 Catch roller 23 Polishing tool 24 Polishing pad 25 Drive motor 26 Cover 27 Second retaining ring 28 Holding pieces 29 Tool spindle 30 Device 31 Drive device 32 Catch roller 33 Gap 34 Support surface 35 Milling tool Z1 axis Z2 axis X1 axis B1 axis C1 axis Lw Longitudinal axis Workpiece holder ring LL Longitudinal axis Optical lens or optical mirror nl Rotational speed n2 Rotational speed n3 Rotational speed n4 Rotational speed R1 Radius R2 Radius α1 Angle α2 Angle OWw Aperture angle Polishing tool OWL Aperture angle Lens Δα Angle difference

Claims

1. Device for polishing an optical lens or optical mirror, comprising a polishing tool and a workpiece holding ring for receiving the optical lens or optical mirror, wherein the workpiece holding ring is arranged in a vertical direction above the tool, characterized by the fact that the device (30) has three axes (X1, Z1, B1) that can be moved during the polishing process for moving the workpiece holder ring (11) and the polishing tool (23).

2. Device according to claim 1, characterized by the fact that the workpiece holder ring (11) with the two movable axes (X1, Z) l ) and the polishing tool (23) is designed to be movable interpolatingly with a movable axis (B1) during the polishing process, and that a center point of the workpiece holder ring (11) is arranged vertically above a center point of the polishing tool (24) during the polishing process.

3. Device according to claim 1 or 2, characterized by the fact thatThe workpiece holding ring (11) is arranged to be in contact with the polishing tool (23) by means of gravity.

4. Device according to one of the preceding claims, characterized by the fact that the optical lens (19) or the optical mirror is arranged against the polishing tool (23) by means of gravity.

5. Device according to one of the preceding claims, characterized by the fact that the workpiece holder ring (11) is rotatably mounted about a longitudinal axis (Lw).

6. Device according to one of the preceding claims, characterized by the fact that at least one smoothing device (20) for a polishing coating (24) of the polishing tool (23) is arranged on a support surface (34) of the workpiece holder ring (11) arranged in the direction of the polishing tool (23).

7. Device according to one of the preceding claims, characterized by the fact thatthe workpiece holder ring (11) is designed to be driven with a first rotational speed (n2) and the polishing tool (23) with a second rotational speed (n1) and that the polishing process can be carried out with two different rotational speeds (n1, n2), wherein one direction of rotation of the workpiece holder ring (11) and one direction of rotation of the polishing tool (23) are synchronous.

8. Device according to one of the preceding claims, characterized by the fact that The workpiece holding ring (11) can be exchanged for a second holding ring (27) with a driven tool spindle (29) for machining a surface of the polishing tool (23).

9. Device according to claim 8, characterized by the fact that during the machining process of the surface of the polishing tool (23) four movable axes (X1, Z1, B l , C l are designed to be movable.

10. Device according to one of the preceding claims, characterized by the fact thatspherical optical lenses (19) or spherical optical mirrors or plane optical lenses or plane optical mirrors can be polished with the device (30).

11. Method for polishing an optical lens or optical mirror with a polishing tool for polishing the optical lens or optical mirror, wherein the optical lens or optical mirror is arranged in a workpiece holding ring, the workpiece holding ring being arranged in a vertical direction above the polishing tool, characterized by the fact that The polishing process is carried out using three movable axes (X1, Z1, B1) for moving the workpiece holder ring (11) and the polishing tool (23).

12. Method according to claim 11, characterized by the fact thatThe workpiece holder ring (11) with the two movable axes (X1, Z1) and the polishing tool (23) with the one movable axis (B1) are moved interpolating during the polishing process, such that a center point of the workpiece holder ring (11) is arranged vertically above a center point of the polishing tool (23) during the polishing process.

13. Method according to claim 11 or 12, characterized by the fact that the optical lens (19) or the optical mirror rests on the polishing tool (23) by means of gravity.

14. Method according to claim 11, 12 or 13, characterized by the fact that The workpiece holder ring (11) rests on the polishing tool (23) by means of gravity.

15. Method according to any one of claims 11 to 14, characterized by the fact thatthe workpiece holder ring (11) is rotatably driven about a longitudinal axis (Lw) during the polishing process, and that the optical lens (19) or the optical mirror arranged in the workpiece holder ring (11) is rotated about a longitudinal axis (L) by friction with the workpiece holder ring (11). L ) of the optical lens (19) or of the optical mirror rotates.

16. Method according to any one of claims 11 to 15, characterized by the fact that at least one smoothing device (20) which is arranged on a support surface (34) of the workpiece holder ring (11) arranged in the direction of the polishing tool (23), smooths the polishing coating (24) during the polishing process.

17. Method according to any one of claims 11 to 16, characterized by the fact thatthe workpiece holder ring (11) is driven with a first rotational speed (n2) and the polishing tool (23) with a second rotational speed (n1), and the polishing process (23) is carried out with two different rotational speeds (n1, n2), wherein one direction of rotation of the workpiece holder ring (11) and one direction of rotation of the polishing tool (23) are synchronous.

18. Method for processing a polishing surface of a polishing tool with a device (30) having the features according to claim 8, characterized by the fact that the machining process for machining the surface of the polishing tool (23) with an interpolating movement with four movable axes (X1, Z) l , B l , C1).

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