EP3463751A1

EP3463751A1 - Tool, device, and method for polishing lenses

Info

Publication number: EP3463751A1
Application number: EP17729015.2A
Authority: EP
Inventors: Gunter Schneider; Stephan Huttenhuis; Andreas Fedoseew; Nadine Geist
Original assignee: Schneider GmbH and Co KG
Current assignee: Schneider GmbH and Co KG
Priority date: 2016-06-06
Filing date: 2017-06-02
Publication date: 2019-04-10
Also published as: DE102016006741A1; US11890712B2; US20190126425A1; WO2017211467A1; CN109414795A

Abstract

The invention relates to a tool, to a device, to a method, and to a use for the zonal polishing of optical workpieces, wherein the tool has a preformed cap for forming a polishing surface and the tool is placed against the workpiece to be polished in such a way that the tilt angle of the axis of rotation of the tool to the normal of the contact surface on the workpiece and/or the size of the contact surface remains at least substantially constant.

Description

Tool, apparatus and method for polishing lenses

The present invention relates to a tool according to the preamble of claim 1, a device according to the preamble of claim 8 and a method according to the preamble of claim 15 and a use of the tool, in particular for only zonal polishing of optical workpieces, in particular lenses ,

The present invention is particularly concerned with the zonal polishing of optical workpieces. The tool (polishing tool) has a polishing surface, which is applied only partially in the region of a contact surface on the workpiece to be polished or can be applied. This contact surface is substantially smaller in comparison to the surface of the workpiece to be polished, in particular with respect to the radial extent of the workpiece. For the purposes of the present invention, "zonal" is to be understood in particular as meaning only polishing with such a "small" contact surface. In contrast, so-called pot tools with their contact surface or their abutment edge extend over the entire radius of a workpiece surface to be polished. With the proposed zonal polishing in particular also a polishing of aspherical and / or free-formed surfaces or workpieces is possible.

For zonal polishing in particular mushroom-shaped polishing tools are used, wherein a curved head of the tool carries a flexible or elastic polishing element to form a curved polishing surface. For example, EP 1 798 872 B1 shows such a tool. During polishing, the polishing surface of the tool lies partially in the region of its abutment surface on the workpiece, in which case the tilt angle between the surface normal of the abutment surface and the axis of rotation of the tool is continuously changed so that the abutment surface on the tool moves along a longitude.

Zonal polishing is used in particular for precision optics or workpieces with aspherical surfaces, for example for mirrors or in particular lenses, and in particular for correcting manufacturing errors. Accordingly, it is important to allow the most accurate or defined processing possible. During polishing, there is always a certain removal of material on the workpiece. DE 10 2004 047 563 A1 discloses a method for polishing a rotating workpiece with a tool having a rubber membrane or a plunger with a glued-on polyurethane membrane. On the exact structure of the tool will not be discussed.

The present invention has for its object to provide a tool, a device and a method and a use for particular zonal polishing of optical workpieces, with a particularly accurate or defined polishing of the respective workpiece, in particular an aspherical surface, preferably simple design is possible.

The above object is achieved by a tool according to claim 1, a device according to claim 8, a method according to claim 15 or a use according to claim 21. Advantageous developments are the subject of the dependent claims.

According to a first aspect of the present invention, the tool has an elastic cap for forming a polishing pad, preferably the cap for preforming the curvature of a curved head of the tool preformed and / or stress-free on the head sits or is. Thus, a particularly defined spring behavior of the cap or the Poier surface formed therefrom can be achieved in a simple manner. In particular, by preforming or shaping prior to attaching or gluing the cap to the tool head, it is possible to avoid or at least minimize otherwise undefined deformations, stresses and the like occurring in the cap material during adaptation to the curvature. Preferably, the cap has a multilayer structure and in particular has an intermediate element and a polishing element. This is the achievement of the desired properties, in particular with regard to the spring behavior, the abrasion behavior and the polishing behavior, conducive. In particular, the polishing element forms a polishing pad or a polishing film or polishing layer. Preferably, in the present invention, generally, the polishing surface or polishing pad formed by the cap or polishing member forms a polishing agent carrier for a polishing agent. The proposed polishing refers to the polishing with a polishing agent, which is in particular in the form of a suspension with polishing particles, such as very fine granules, particles o. Dg.., Is present or used. In particular, the polishing surface also serves to transport the polishing agent into an effective gap between the contact surface of the tool and the surface to be polished and / or to disperse or move therein and / or to rub it with the polishing agent on the surface.

In particular, the polishing reduces the roughness of the surface and / or the cracks in the material which have arisen during previous shaping, for example by grinding, can be removed. In each case, material is removed. The removed material is also conveyed away from the working gap between the polishing surface and the surface to be polished by the tool or the polishing surface by means of the poying agent.

In general, therefore, the present invention relates in particular to the polishing of a workpiece with the aid of a tool and a polishing agent. However, the polishing can alternatively be done without separate or additional polish, but only with the tool.

Depending on the polishing agent, the polishing surface is optionally porous or non-porous and / or provided with a favorable surface structure or texture in order to achieve the desired polishing effect, in particular with a specific polishing agent in the respective workpiece material.

Preferably, the intermediate element and also the polishing element are preformed or shaped to adapt to the curvature. The polishing element is then adapted to the shape of the intermediate element by previous shaping. Thus, tensions between the two elements can be avoided or at least minimized.

The preforming can be done, for example, by appropriate foaming or other prototyping with the desired shape. The molding is preferably carried out by material removal or mechanical processing of the cap or the cap-forming elements, in particular by milling and / or turning, for example, plate or solid material. The polishing element is preferably substantially thinner than the intermediate element.

Preferably, the cap or the intermediate element and the polishing element are glued. This allows a simple structure.

Particularly preferably, the tool in the region of the head on a collar or other stop for circumferential support and / or positioning of the cap. This is conducive to simple and defined production. According to a second, independently realizable aspect of the present invention, a proposed device and a proposed method are characterized in particular by the diameter of the contact surface of the tool on the workpiece and / or the tilt angle of the axis of rotation of the tool to the normal (surface normal) of the contact surface during the polishing of the workpiece, that is, during the respective polishing process, is kept at least substantially constant or become. This is conducive to defined polishing with in particular defined material removal.

According to a third, independently realizable aspect of the present invention, the proposed device and the proposed method are particularly characterized in that the tool is moved from an edge of a surface to be polished of the workpiece over the middle to the opposite side of the edge or is movable. This allows a particularly uniform polishing, especially in the area of the optically important and sensitive center of the workpiece. The usual stopping or ending of the polishing process in the region of the center usually leads to an uneven and / or undefined material removal.

According to a fourth, independently realizable aspect of the present invention, the indentation depth of the particular elastically deformable polishing surface on the tool is preferably varied, controlled or regulated by corresponding delivery of the tool relative to the workpiece during the polishing process, particularly preferably as a function of the radial position the contact surface the workpiece, the desired diameter of the contact surface, the (desired) contact pressure of the tool on the workpiece and / or the profile of the workpiece, in particular the curvature of the workpiece in the region of the respective contact surface. This contributes to a defined polishing and a defined material removal, whereby an optimization of the time required for the polishing is also made possible.

According to a fifth aspect of the present invention, which can also be implemented independently, the distance of adjacent tracks of the preferably spiral-shaped polishing path of the contact surface on the workpiece or the surface to be polished is optionally kept at least substantially constant. This is conducive to a defined polishing or a defined material removal.

According to a sixth aspect of the present invention, which can also be implemented independently, the rotation speed of the workpiece during one rotation is optionally dependent on the rotational position, a locally desired dwell time (polishing time), the diameter of the contact surface, the contact pressure of the tool on the workpiece and / or the profile of the workpiece, in particular in the region of the respective contact surface, varies or is controlled or regulated. In this way, taking into account the actual three-dimensional course of the surface to be polished, optimum polishing with defined material removal and / or influencing or controlling can be achieved.

According to a seventh, independently realizable aspect of the present invention, the tool is preferably provided with a polishing surface, which is formed from at least substantially closed pores, in particular wherein the polishing surface to more than 1 or 5% (based on the areal extent or number of pores) by Pores with a size of more than 0.5 mm and / or more than 25 or 50% (based on the areal extent or the number of pores) of pores with a size of less than 0.4 or 0.3 mm, more preferably less than 0.1 mm, and / or in particular wherein the size of the pores on the polishing surface is less than 1 mm, in particular less than 0.9 mm, and / or in particular wherein the polishing surface is not machined or not dressed. The size of the pores in particular the average or maximum diameter is considered. It has emerged from experiments that such a polishing surface exhibits particularly good polishing properties, in particular when polishing precision optics or glass. Particularly preferred is the polishing surface or the polishing pad or cap forming this polyurethane or other suitable foam or

Made of plastic. Preferably, the tool is used for zonal polishing or prepared and prepared for the apparatus for polishing, so is a (further) onsieren or dressing of the polishing tool when new in the polishing machine, as in particular in the precision machining usual, not (more) required. Particularly preferably, the workpiece to be polished is first measured and errors can then be corrected by correcting polishing with the proposed tool, the proposed device or the proposed method. The proposed tool, the proposed device and / or the proposed method can be used in particular for Vorpolteren and / or Korrekturpolieren.

The aforementioned and following aspects and features of the present invention can be combined with one another as desired, but can also be implemented independently of one another.

Further aspects, features, advantages and features of the present invention will become apparent from the claims and the following description of a preferred embodiment with reference to the drawing. It shows:

Fig. 1 is a schematic representation of a proposed device for polishing an optical workpiece, wherein different positions of a proposed tool with associated tool spindle are shown;

Fig. 2 is a schematic section of the proposed tool;

Fig. 3 is a schematic plan view of a surface to be polished of

Workpiece, wherein a contact surface of the tool and the distance traveled on the workpiece polishing path are schematically indicated; and 4 shows a partial enlargement of FIG. 1 for illustrating the tool head resting on the workpiece.

1 shows, in a schematic representation, a proposed device 1 for, in particular, zonal polishing of an optical workpiece 2, in particular a lens, a mirror or the like, particularly preferably of glass.

The device 1 is designed for polishing the workpiece 2 by means of a particular proposed tool 3 or other tool. The preferred structure of the proposed polishing tool 3 will be explained in more detail in particular with reference to FIG. 2.

In the illustration according to FIG. 1, the tool 3 is shown together with an associated tool spindle 13 of the device 1 in three different positions, in particular for illustrating the movability of the tool 3 or a preferred method sequence.

The proposed tool 3 is shown in a schematic section in Fig. 2. It preferably has a carrier 4 with a curved head 5 and a particular hemispherical or conical cap 6.

The cap 8 is preferably of multilayer construction and, in the illustrated embodiment, preferably has an intermediate element 7 and a polishing element 8.

The tool 3, the cap 8 or its intermediate element 7 is attached to the head 5 of the tool 3, in particular adhesively bonded thereto.

The cap 8 or its polishing element 8 forms a polishing surface 9.

The polishing surface 9 of the tool 3 or the cap 8 or of the element 8 is preferably curved convexly, in particular geometrically similar to the head 5 or curved to suit and / or preferably spherical or hemispherical and / or conical.

The polishing element 8 is mounted on the intermediate element 7, in particular glued to this. Alternatively, however, the cap 6 may also be formed in one piece and / or produced in a multilayered manner by bi-injection or the like.

The cap 6 or the intermediate element 7 and / or the polishing element 8 is or are preferably made of plastic or foam and / or of an elastic and / or flexible material.

Particularly preferably, the intermediate element 7 is made of a preferably closed-cell foam, in particular of polyurethane.

The cap 6 or the intermediate element 7 preferably has a static modulus of elasticity with a static permanent load of more than 0.5 N / mm ² , preferably more than 1 N / mm ² , in particular more than 1.5 N / mm ² , and / or less than 30 N / mm ² , preferably less than 15 N / mm ² , in particular less than 7.0 N / mm ² , and / or a dynamic elastic modulus at a dynamic continuous load of 10 Hz of more than 0.5 N / mm ² , preferably more than 1 N / mm ² , in particular more than 1.3 N / mm ² , and / or less than 20 N / mm ² , preferably less than 10 N / mm ² , in particular less than 8.0 N / mm ² , and / or a compression hardness at 10% deformation of more than 0.05 N / mm ² , preferably more than 0.1 N / mm ² , in particular more than 0.2 N / mm ² , and / or less as 3 N / mm ² , preferably less than 2 N / mm ² , in particular less than 1 N / mm ² , in each case in particular measured according to DIN 53513: 1990-03.

The polishing element 8 is preferably made of a harder and / or stiffer material than the intermediate element 7.

The polishing element 8 is preferably formed thin-walled and / or foil-like.

The density, preferably in accordance with DIN EN ISO 845: 2009-10, of the polishing element 8 is preferably more than 300 kg / m ³ , in particular more than 500 kg / m ³ , particularly preferably more than 700 kg / m ³ , and / or preferably less than 4000 kg / m ³ , in particular less than 3000 kg / m ³ , particularly preferably less than 2000 kg / m ³ . The polishing element 8 or the cap 6 or polishing surface 9 preferably has a Shore A hardness of more than 5, in particular more than 10, more preferably more than 20, and / or preferably less than 90, in particular less than 80, more preferably less than 70, in particular according to DIN ISO EN 868: 2003-10 or DIN ISO 7619-1: 2012-02, on.

The polishing element 8 preferably has a thickness of more than 0.1 mm, in particular more than 0.3 mm, more preferably more than 0.4 mm, and / or preferably less than 3 mm, in particular less than 2 mm, more preferably less than 1 mm, on.

The thickness of the intermediate element 7 is preferably more than 2 mm and / or less than 10 mm, in particular about 3 to 7 mm.

The thickness of the intermediate element 7 is preferably at least 5 times, in particular approximately 10 times, the thickness of the polishing element 8 or more. The cap 6, the intermediate element 7 and / or the polishing element 8 preferably has or each have an at least substantially constant thickness.

The polishing element 8 or the polishing surface 9 is preferably formed or produced from an open-cell or closed-cell plastic or composite material or the like.

In the illustrated example, the polishing element 8 is preferably made of a plastic film or of polyurethane. The cap 6 or the intermediate element 7 and / or polishing element 8 is or are preformed or shaped to conform to the curvature of the head 5 and / or to achieve a desired curvature or other shape, such as a ball, preferably inside and / or outside, So adjusted before attaching to the tool 3 and head 5 in their shape of the head 5, in particular provided with a complementary curvature to the head 5 and intermediate element 7.

The tool 3 or the head 5 preferably forms a solid or non-compliant surface made of metal or other suitable material for the support and in particular also attachment of the cap 6 or elements 7, 8 arranged thereon. The shaping or shaping of the cap 6 or of the intermediate element

7 and / or polishing element 8 is particularly preferably mechanically, in particular by turning and / or milling. Particularly preferred Voilmaterial is machined to the desired shape mechanically.

The mechanical processing has the advantage that a very uniform material layer, without material compression, deformation or other Materialunre- irregularities with the desired shape, in particular a cap-like or spherical, possibly also other shape can be produced.

Alternatively, the said shaping can also take place, for example, by appropriate foaming or other prototyping.

The preformed or machined cap 6 or correspondingly preformed or machined elements 7 and 8 is or are attached to the tool 3 or head 5, in particular by gluing. Particularly preferably, the polishing element 8 is attached to the intermediate element 7 by gluing. However, another connection can be made with it.

Particularly preferred is or sits the cap 6 and the intermediate element 7 on the head 5 without tension.

According to the invention, "stress-free" means, in particular, that in the applied state no local material deformations or stresses in the material of the cap 6 or elements 7, 8 occur due to adaptation to the curvature, which is caused by deformation during adaptation to the arched shape - He would and a uniform and in particular defined spring and damping behavior of the cap 6 or elements 7, 8 adversely affect (can).

Preferably, accordingly, the polishing element 8 should be mounted stress-free in this sense, in particular to avoid any wrinkling. Particularly preferably, the polishing element 8 is adapted to the curvature of the outside of the intermediate element 7 by appropriate preforming, in particular shaping, prior to attachment to or connection to the intermediate element 7,

The tool 3 or the cap 6 or the polishing element 8 or the polishing surface

9 is in particular designed such that an unillustrated polishing agent transported over the polishing surface 9 and thereby the workpiece 2 processed in a mechanical-chemical removal process and thereby can be polished, as already described above.

To facilitate the attachment and / or positioning of the cap 6 or elements 7, 8, the tool 3 or its carrier 4 preferably has a collar

10 or other stop, which in particular projects laterally from the head 5 and / or forms a preferably circumferential shoulder or the like.

The tool 3 or the carrier 4 preferably has a connection section

1 1 and / or a stop 12 for the defined attachment or mounting of the tool 3 to the associated tool spindle 13 or the tool chuck 14 o. The like.

Particularly preferably, the tool 3 is clamped or fastened to the tool spindle 13 by means of the tool chuck 14. The stop 12 in this case serves in particular a defined axial position of the tool 3 on the tool spindle 13 or on the tool chuck 14. However, other design solutions are also possible.

Preferably, tools 3 with different curvature radii of the head 5 or the cap 6 or the polishing surface 9 are used depending on the shape of the surface 2A to be polished.

The radius of curvature of the polishing surface 9 is preferably more than 2 mm, in particular more than 3 mm or 5 mm, and / or preferably less than 1000 mm, in particular less than 500 mm, particularly preferably less than 100 mm, preferably as a function of the (maximum ) Curvature of the surface to be polished 2A and / or the desired use. When correcting polishing namely tools 3 are used with smaller radii of curvature of preferably below 00 mm. The distance of the polishing surface 9, in particular at the intersection with the axis of rotation R, to the stop 12 is preferably the same for all tools 3 even with different curvature or curvature.

The device according to the preamble 1 has the tool spindle 13 for rotating the associated or clamped tool 3 about an axis of rotation R, as indicated in FIG. 1. The rotational speed is preferably about 1000 to 5000 revolutions per minute.

The rotational speed is preferably controlled or regulated. Preferably, the rotational speed is kept constant during the polishing process. However, in principle also a change in the rotational speed during a polishing operation or an adaptation of the rotational speed to a respective tool 3 and / or workpiece 2 or for each polishing operation is possible.

The rotation of the tool 3 is preferably carried out without detection of the angle of rotation. It is therefore not a controlled axis of rotation in the sense of a CNC control. The tool spindle 13 and thus the tool 3 are pivotable about a pivot axis B. In particular, it is a controlled or controlled pivot axis or C C-axis, also called rotary axis. In particular, the pivotal position is detected. Thus, a defined pivoting is enabled, as exemplified by the three different positions shown in FIG.

The pivot axis B runs in the representation example transverse and in particular perpendicular to the axis of rotation R or drawing plane.

The pivot axis B is preferably arranged as close as possible to the tool 3 or to the polishing surface 9 and / or to the tool chuck 14. The device 1 has a workpiece drive 15, in particular a workpiece spindle, for the workpiece 2, so that the workpiece 2 to be polished is rotatable about the rotation axis C with a defined angular position. Preferably, the workpiece 2 is held by a holder 18, such as a block piece, and / or held by means of a chuck on the workpiece drive 1 5 with a defined angular position or coupled with this.

The rotation axis C is in particular a controlled or controlled axis or a CNC axis, also called a rotary axis. Preferably, therefore, the rotational angle position is detected here. Particularly preferably, an angle-dependent variation of the rotational speed is made possible even within one revolution. The rotational speed of the workpiece drive 15 or of the workpiece 2 is generally variable, in particular, for example, from about 10 or 20 revolutions per minute (for polishing at the edge 2C of the side 2A of the workpiece 2 to be polished) up to about 2000 to 3000 revolutions per minute (FIG. for polishing in the area of the center 2B of the workpiece 2).

The C-axis preferably extends in a plane with the axis of rotation R (independent of the pivotal position of the tool spindle 13) and / or transversely or perpendicular to the pivot axis B. The workpiece drive 15 and thus the workpiece 2 are preferably linearly movable in the Z direction or adjustable, as indicated in Fig. 1. The adjustment is carried out in particular by means of a carriage and adjusting drive, not shown, or the like. The Z axis preferably runs parallel to the C axis and / or transversely or perpendicular to the pivot axis B.

The tool spindle 13 and thus the tool 3 is preferably adjustable transversely in the X direction, in particular by means of a carriage, not shown, and one associated drive. This carriage then preferably also carries the B axis and the corresponding pivot drive for pivoting the tool spindle 13. The X-axis and Z-axis are preferably each formed as a controlled or controlled axis or as a CNC axis or linear axis, so that an accurate positioning in the X and Z directions is made possible. The X-axis preferably runs transversely or perpendicular to the C-axis, B-axis and / or Z-axis.

The X-axis preferably runs in or parallel to the common plane of the C-axis and R-axis.

The axes can also be stacked or distributed differently. For example, the Z-axis of the tool spindle 13 may be assigned instead of the workpiece drive 15. Alternatively or additionally, it is also possible that the B-axis and / or X-axis are not realized on the tool side, but on the workpiece side.

However, it is desirable to distribute the axes on the tool side and workpiece side to allow greater machining accuracy.

The device 1 is, in particular, a polishing machine or CNC machine with X, Z, B and C axes.

Preferably, the X-axis and / or the B-axis is horizontal.

Particularly preferably, the C-axis and / or the Z-axis is vertical.

Particularly preferably, the polishing tools 3 are each with their polishing surfaces 9 in height or in the vicinity of the B axis, so that the contact surface A can be pivoted as possible with a minimum radius. The B-axis is preferably less than 100 or 50 mm, in particular less than 30 or 1 5 mm, more preferably less than 10 mm from the polishing surface 9 or contact surface A, in particular from the intersection of the axis of rotation R with the polishing surface 9, spaced , In particular, this distance is preferably at least substantially the same for tools 3 with other radii of curvature of the polishing surface 9.

The B-axis preferably intersects the axis of rotation R within the cap 6 or polishing surface 9. By appropriate relative adjustment, ie in particular by moving in X- and Z- direction and by pivoting about the B-axis, the tool 3 in particular as indicated by arrow W in Fig. 1 and in Fig. 3 schematically on the workpiece 2 and the surface to be polished 2A are moved.

The tool 3 is particularly preferably moved starting from an edge 2C of the workpiece 2 or the surface 2A toward the center 2B and beyond it to the opposite side of the edge 2C, as illustrated in FIGS. 1 and 3. By interrupting or terminating the polishing process in the region of the center 2B, as is customary in the prior art, this avoids and thereby enables or ensures a more optimal processing or a defined removal of material. During polishing, the polishing surface 9 of the tool 3 lies only in regions with a contact surface A on the workpiece 2 to be polished or its surface 2A, as shown schematically in particular in FIG. 4, which represents a fragmentary enlargement of the dash-dotted circular region of FIG. The contact surface A is preferably at least substantially circular, depending on the three-dimensional shape of the surface 2A. In the schematic plan view of FIG. 3, the contact surface A, with which the polishing surface 9 rests against the workpiece 2 or the surface 2A, is also indicated. Preferably, the plane normal N intersects the axis of rotation R of the tool 3 at a (relative) tilt angle K, as indicated in FIGS. 1 and 4. In particular, polishing with the tool 3 takes place in such a way that the contact surface A lies off-center with respect to the axis of rotation R on the polishing surface 9. In other words, (preferably always) with a tilt angle K of more than 0 °, in particular more than 2 °, particularly preferably more than 5 ° or 10 °, and / or preferably less than 50 °, in particular less than 30 °, more preferably less than 25 °, worked or polished.

Particularly preferably, the tilt angle K is kept constant during the polishing process. This is achieved by corresponding pivoting of the tool spindle 13 and the tool 3. The swivel angle S (angle of the rotation axis R to the C axis) then varies accordingly along the tool path W, as indicated schematically in FIG. 1, for example, by a small swivel angle. Angle S in the left position over a mean swivel angle S in the middle position to a large swivel angle S in the right position.

In particular, a polishing process in the sense of the present invention designates the complete polishing of the surface 2A of the workpiece 2 to be polished with a tool 3. In such a process, as already explained, the tool path W is traversed or traversed by the tool 3, while on the one hand the tool 3 and on the other hand, the workpiece 2 rotates. During the polishing process, the contact surface A or its center AM then passes over the surface 2A to be polished into a particularly spiral polishing path P, as indicated in FIG. 3, however, only schematically. Namely, the spiral polishing path P is passed through once when the tool 3 or the abutment surface A moves from the edge region 2C to the center 2B or to the rotational axis C, respectively. However, the same or a corresponding spiral polishing path P is then run through again when the tool 3 or the contact surface A moves further away from the tool path W from the center 2B to the outside towards the edge region 2B. The device 1 is particularly preferably designed or controlled such that a uniform spiral or an at least substantially constant distance PA between adjacent polishing tracks PS of the polishing path P is reached or passed through, as indicated in FIG. 3. The distance PA is therefore particularly preferably kept at least substantially constant. However, the distance PA may alternatively vary, in particular depending on the workpiece radius at which the center of the contact surface (even) is located.

The diameter AD of the contact surface A is particularly preferably at least by a factor of 10 or 20 greater than the spiral spacing or spacing PA of adjacent polishing tracks PS.

Preferably, the tool 3 rotates opposite to the workpiece 2. However, a rectified rotation is possible.

Preferably, the tool 3 rotates (much) faster than the workpiece 2. In order to achieve a similar or, if possible, identical retention time of the tool 3 or the contact surface A over a surface area of the surface 2A, the rotational speed of the workpiece 2 and, consequently, the speed of movement of the workpiece 2 along the tool path W are constant increased from the edge 2C towards the center 2B and then reduced again towards the edge.

Alternatively or additionally, the rotational speed of the workpiece 2 during one revolution, in particular depending on the rotational position, the diameter AD of the contact surface A, the contact pressure of the tool 3 on the workpiece 2, the Eindiefeiefe E of the polishing surface 9 and / or the profile of the workpiece. 2 be varied in order to achieve a particularly uniform material removal or a desired polishing result. This allows in particular a highly accurate polishing processing.

Particularly preferably, the device 1 is embodied or the proposed method is implemented such that the size or the diameter AD of the abutment surface A is at least substantially kept constant during the polishing process. This is conducive to a uniform or defined material removal.

The size or the diameter AD of the contact surface A is determined in particular by the in Fig. 4 schematically indicated Eindiefeiefe E of the polishing surface 9 by appropriate delivery of the tool 3 during the polishing process, but also depends on the surface shape of the workpiece 2, in particular the respective Curvature ratios and from the curvature of the polishing surface 9 from. By varying the infeed of the tool 3 during the polishing process, the indentation depth E of the polishing surface 9 and thus also the size or diameter AD of the abutment surface A are correspondingly varied.

Particularly preferably, the indentation depth E of the polishing surface 9 is varied by appropriate infeed of the tool 3 during a polishing operation such that an at least substantially constant diameter AD is obtained, even with different curvatures of the surface 2A to be polished, particularly preferably with an aspherical surface 2A the contact surface A is enough. This is conducive to uniform or defined material removal over the entire polishing process.

Alternatively, it can also be provided that the diameter AD of the contact surface A decreases from the edge 2C to the center 2B and increases in the reverse direction.

The speed of the C-axis, that is, the rotational speed of the workpiece 2, is preferably derived from calculated residence times of the contact surface A over certain partial surfaces of the surface 2A to be polished.

Preferably, in order to correct local rotationally asymmetrical errors of the surface 2A to be polished, the web speed or rotational speed of the workpiece 2 is changed within one revolution. In this way, in particular within one revolution, different polishing or residence times, depending on the required error correction, can be realized.

In particular, the speed of the X-axis is adjusted so that the desired constant spiral spacing or spacing PA of adjacent polishing tracks PS remains constant per revolution. Accordingly, then the feed in the X direction is directly coupled to the speed or number of revolutions of the C axis or vice versa.

Preferably, the optimum dwell time of the tool 3 or of the contact surface A is determined in advance by means of local areas on the surface 2A of a simulation to be polished. Subsequently, the corresponding web positions and web speeds are determined from the calculated local residence times. The optimum indentation depth E of the polishing surface 9 or delivery of the tool 3 on the workpiece 2 is optimally determined depending on the tool 3 and geometry of the surface 2 to be polished, in particular by means of appropriate calculations, estimates and / or measurements, the indentation depth E during the polishing process in particular is adjusted so that the diameter AD of the contact surface A remains as constant as possible.

The proposed polishing tool 3 is characterized in particular by a cap 6 or a cap structure with defined spring and damping properties. shadow out. Thus, by the Eindrückiefe E very accurately the size of the contact surface A can be influenced.

The indentation depth E is preferably more than 0.1 mm and / or less than 0.8 mm.

The size or the diameter AD of the contact surface A is preferably more than 1 mm, in particular more than 3 mm, and / or less than 25 mm, in particular less than 15 or 10 mm.

A zonal polishing of the workpiece 2 is particularly preferred. "Zonal" means that the contact surface A is substantially smaller than the surface 2A of the workpiece 2 to be polished, in particular with respect to the radial extent of the workpiece 2 average or largest diameter AD of Aniageflache A much smaller than the mean or largest radius of the workpiece 2. Particularly preferably, the mean or largest radius of the workpiece 2 at least by a factor of 2, 3 or 5 is greater than the mean or largest diameter AD of the contact surface A. During polishing, additional parameters can additionally be taken into account, as explained in particular in DE 10 2009 004 787 A1, which is hereby referred to in this regard as a supplementary disclosure.

In particular, the device 1 also has a feed, not shown, for polishing agents, as usual in polishing machines, so that the polishing agent can be supplied in the desired manner during polishing.

The proposed tool 3, the proposed device 1 and / or the proposed method can or can be used in particular for polishing precision optics or aspherical surfaces or other optical workpieces, preferably measuring the surface shape before polishing and thus by polishing a desired Surface shape can be achieved. This is also called correction polishing. The polishing can be carried out in particular with an accuracy of 10 to 100 nm. Tools 3 with smaller radii of curvature of the polishing surface 9, in particular with radii of curvature of less than 100 mm, more preferably less than 50 mm, are preferably used for correction purposes. Tools 3 with larger radii of curvature of the polishing surface 9, in particular of up to 1000 mm, are preferably used for pre-polishing.

After the optimal pre-polishing, it is preferable to measure the surface 2A to be processed and then to correct the polishing.

The proposed device 1 and the proposed method can basically be used both for pre-polishing and for corrective polishing. Individual aspects and features of the present invention can be implemented independently of one another, but also in any desired combination.

LIST OF REFERENCE NUMBERS

1 device

2 workpiece

2A surface of the workpiece

2B Center of the workpiece

2C edge of the workpiece

3 tool

4 carriers

5 head

8 cap

7 intermediate element

8 polishing element

9 polishing surface

10 frets

1 1 connection section

12 stop

13 tool spindle

14 tool chuck

15 workpiece drive

16 holders

A contact surface

AD Diameter of the contact surface

AM center of the contact surface

B pivot axis

C axis of rotation of the workpiece

E indentation depth

K tilt angle

N normal

P polishing path

PA Distance of polishing marks

PS polishing track

R axis of rotation of the tool

S swivel angle

W tool path

X linear axis

Z linear axis

Claims

Patent claims:

1 . Tool (3) for preferably zonal polishing of optical workpieces (2), in particular lenses,

with a curved head (5) and an elastic cap (6) arranged thereon to form a polishing surface (9),

characterized,

that the cap (6) is preformed or shaped to adapt to the curvature of the head (5) and/or is tension-free on the head (5).

2. Tool according to claim 1, characterized in that the cap (6) is constructed in multiple layers.

3. Tool according to claim 1 or 2, characterized in that the cap (6) has an intermediate element (7) and a polishing element (8).

4. Tool according to claim 3, characterized in that the intermediate element (7) and / or the polishing element (8) is or are preformed or shaped to adapt to the curvature.

5. Tool according to claim 3 or 4, characterized in that the polishing element (8) is adapted to the shape of the intermediate element (7) by prior shaping.

6. Tool according to one of the preceding claims, characterized in that the cap (6) has an at least substantially constant thickness.

7. Tool according to one of the preceding claims, characterized in that the tool (3) in the area of the head (5) has a collar (10) or other stop for circumferential support and / or positioning of the cap (6).

8. Device (1) for preferably zonal polishing of optical workpieces (2), in particular lenses,

with a tool spindle (13) for rotating a tool (3) and with a workpiece lifter (1 5) for rotating a workpiece (2) to be polished, where the tool lockers! (13) and the workpiece drive (15) can be pivoted and/or adjusted relative to one another, so that a polishing surface (9) of the tool (3) can be placed partially in the area of a contact surface (A) on the workpiece (2) to be polished, in particular wherein the center point (AM) of the contact surface (A) covers a spiral polishing path (P) on the workpiece (2),

characterized,

that the device (1) is designed such that the tool (3) is moved from an edge (2C) of a surface (2A) of the workpiece (2) to be polished across the center (2B) to the opposite side of the edge (2C). , and/or that the device (1) is designed such that the diameter (AD) of the contact surface (A) and/or the tilt angle (K) of the axis of rotation (R) of the tool (3) is relative to the normal (N) of the Support surface (A) is or will be kept at least substantially constant during polishing.

9. Device according to claim 8, characterized in that the device (1) is designed such that the tool (3) is relative to the workpiece

(2) is delivered and/or moved so that the diameter (AD) of the contact surface (A) is at least a factor of 10 or 20 larger than the distance (PA) of adjacent tracks (PS) of the polishing path (P) of the contact surface (A) on a surface (2A) of the workpiece (2) to be polished.

10. Device according to claim 8 or 9, characterized in that the workpiece drive (15) forms a controlled axis of rotation (C) for the workpiece (2).

1 1 . Device according to one of claims 8 to 10, characterized in that the rotation speed of the workpiece (2) during one revolution depends on the rotational position, the profile of the workpiece (2), the diameter (AD) of the contact surface (A), the indentation depth (E) the polishing surface (9), the contact pressure of the tool (3) on the workpiece (2) and / or the locally desired dwell time or polishing time can be varied or controlled or regulated.

12. Device according to one of claims 8 to 1 1, characterized in that different tools (3) with different radii of curvature of the polishing surface (9) can be used.

13. Device according to one of claims 8 to 12, characterized in that the distance of a pivot axis (B) for pivoting the tool (3) relative to the workpiece (2) is from an intersection of the axis of rotation (R) of the tool spindle (13) with the Polishing surface (9) is less than 100 mm and/or is at least essentially the same size for all tools (3).

14. Device according to one of claims 8 to 13, characterized in that the distance of a pivot axis (B) for pivoting the tool (3) relative to the workpiece (2) is from an intersection of the axis of rotation (R) of the tool spindle (13) with the Polishing surface (9) is at least essentially the same size for all tools (3).

15. A method for preferably zonally polishing a particularly aspherical surface (2A) of an optical workpiece (2), in particular a lens, wherein a tool (3) with a curved polishing surface (9) can be pivoted and/or adjusted relative to the workpiece (2). is, so that the polishing surface (9) of the rotating tool (3) is partially pressed against the rotating workpiece (2) to be polished by pressing in the area of a contact surface (A),

characterized,

that the tool (3) is moved from an edge (2C) of the surface (2A) of the workpiece (2) to be polished across the center (2B) to the opposite side of the edge (2C), and/or

that the diameter (AD) of the contact surface (A) and/or the tilt angle (K) of the rotation axis (R) of the tool (3) to the normal (N) of the contact surface (A) during the polishing of the workpiece (2) is at least in Is or will be kept essentially constant, and/or

that the indentation depth (E) of the polishing surface (9) is varied by advancing the tool (3) during the polishing of the workpiece (2) - in particular depending on the radial position of the contact surface (A) on the workpiece (2), and /or that the distance (PA) between adjacent tracks (PS) of the polishing path (P) is kept at least substantially constant, and/or

that the rotation speed of the workpiece (2) is varied during one revolution, in particular depending on the rotational position, the locally desired dwell time and / or the profile of the workpiece (2).

16. The method according to claim 15, characterized in that the diameter (AD) of the contact surface (A) is kept at least substantially constant by varying the indentation depth (E).

17. The method according to claim 15, characterized in that the diameter (AD) of the contact surface (A) decreases starting from an edge (2C) towards the center (2B) of the surface (2A) to be polished and increases in the opposite direction.

18. The method according to any one of claims 15 to 17, characterized in that the rotation speed of the workpiece (2) increases from polishing at the edge (2C) towards the center (2B) of the surface (2A) and decreases in the opposite direction.

19. Device according to one of claims 15 to 18, characterized in that the center point (AM) of the contact surface (A) covers a spiral polishing path (P) on the workpiece (2).

20. Device according to one of claims 15 to 19, characterized in that the contact surface (A) is significantly smaller than the surface (2A) of the work piece (2).

21. Use of a tool (3) according to one of claims 1 to 7 for zonally polishing a surface (2A) of an optical workpiece (2), in particular a lens,

wherein the tool (3) with its curved polishing surface (9) is pivoted and/or advanced relative to the workpiece (2), so that the polishing surface (9) of the rotating tool (3) is partially pressed in in the area of a contact surface (A) is applied to the rotating workpiece (2) to be polished, with the contact surface (A) covering a polishing path (P) on the workpiece (2).

22. Use according to claim 21, characterized in that the tool (3) is moved from an edge (2C) of the surface (2A) over the center (2B) of the workpiece (2) to the opposite side of the edge (2C).

23. Use according to claim 21 or 22, characterized in that the indentation depth (E) of the polishing surface (9) is determined by advancing the tool (3) during the polishing of the workpiece (2) is varied depending on the radial position of the contact surface (A) on the workpiece (2).

24. Use according to claim 21 or 22, characterized in that the diameter (AD) of the contact surface (a) is kept at least substantially constant by varying the indentation depth (E).

25. Use according to one of claims 21 to 23, characterized in that the diameter (AD) of the contact surface (A) decreases starting from an edge (2C) towards the center (2B) of the surface (2A) and increases in the opposite direction.

26. Use according to one of claims 21 to 23, characterized in that the distance (PA) between adjacent tracks (PS) of the polishing path (P) is kept at least substantially constant.

27. Use according to one of claims 21 to 24, characterized in that the center point (AM) of the contact surface (A) covers a spiral polishing path (P) on the workpiece (2).

28. Use according to one of claims 21 to 25, characterized in that the rotation speed of the workpiece (2) is varied during a revolution depending on the rotational position, the locally desired dwell time and / or the profile of the workpiece (2).

29. Use according to one of claims 21 to 28, characterized in that the rotation speed of the workpiece (2) increases from polishing at the edge (2C) towards the center (2B) of the surface (2A) and decreases in the opposite direction.

30. Use according to one of claims 21 to 29, characterized in that the tilt angle (K) of the axis of rotation (R) of the tool (3) to the normal (N) of the contact surface (A) during the polishing of the workpiece (2) is at least is kept essentially constant.