EP0916448B1 - Method and apparatus for polishing both sides of optical lenses - Google Patents

Description

The invention relates to a method according to the preamble of claim 1. Furthermore, the invention relates a device according to the preamble of claim 8.

DE 34 29 408 A1 describes a method and a Device for surface treatment of an optical Lens. The optical lens is on Polishing process in a bell-shaped chamber a hydraulic cushion between the chamber floor and the lens by a pressurized Hydraulic fluid with one contained therein Polishing suspension is formed. By a rotational movement of the driven tool Processing process on the lens instead.

DE 36 26 324 (D1) describes a double-spindle lathe with three tool turrets and two Chuck, with the tool turret fixed and are not driven and the chuck is rotatable stored and driven. The workpiece is in two machining positions with the tool turret attached tools processed. By that took place between the two processing phases Transfer of the workpiece from one chuck to an opposite one movable feed and deployment of tools on the corresponding sides of the device is a two-sided machining of the workpiece possible.

Optical lenses are made through multiple grinding processes or other exciting machining methods made of transparent materials. It can happen are mineral glass or suitable plastics. To the shaping processes mentioned in any case, at least one polishing process closes with which the surface roughness of the lens is reduced so far that the light scattering at the Surface becomes negligible.

In today's common processes, polishing is used of the lenses takes about twice as long as for the previous shaping processes. It is therefore a particularly important development goal Shorten polishing times. Because the actual polishing time where the polishing tool is engaged on the lens is not easily shortened due to the process reduction in non-productive times special meaning too.

According to the prior art, lenses are made with the following Technology polished:

The polishing machines have an overhead Swivel head that carries the tool spindle on its lower one End of the polishing tool - usually a molding tool - is attached. The swivel head in turn is pivotable around the so-called B axis on one X-carriage attached, the horizontal movements perpendicular to the B axis. In the lower part the polishing machine is a Z slide, the can move vertically and with the workpiece spindle vertical axis. The axes of the tool spindle and workpiece spindle lie in a common plane, that is vertical on the B axis. Both spindles have their own drive that keeps them rotating can move. Other axis divisions are natural just as possible as a swap from top to bottom below.

So that the relative speed between the mold and lens at any point on the lens surface if possible is optimal, one of the two spindle axes be tilted when polishing. With the usual today This is done by swiveling the polishing machine aforementioned, overhead swivel head with it attached tool spindle, which is at an angle stands. The mold has about twice that Diameter like the lens that is attached to the tool will ensure that its edge does not cross the center of rotation of the Forming tool extends. For geometrical reasons the intersection of the two spindle axes with the Center of curvature of the lens coincide what after the tilting of the swivel head by moving the X slide and the Z slide can be reached can.

The molding tools are on the side when polishing lies against the lens, covered with a soft material. By adding a polishing suspension, the fine Contains solid particles, the desired material removal reached. If essentially when polishing only the surface roughness is reduced, so there is still some correction in the fine area the lens shape instead. For this reason, the Polishing tools must be worked very precisely and because of the wear and tear that occurs during polishing again and again reworked with a so-called dressing tool become. Previously, the workpiece holder of the workpiece spindle are removed so that the dressing tool could be attached to this spindle. When changing the components, there were tolerance errors with regard to the axis position of the workpiece holder, Dressing tool and contour of the forming tool through the natural tolerances of those involved Components. This tolerance error in the axis position of the components involved led to a reduction the lens accuracy.

There have recently been dressing tools available with a Workpiece holder are combined, in the following combination tool called. A corresponding device was created described under the official file number 961 07 870.6 and patent pending. When using this Combination tools are the aforementioned tolerance problems avoided because the workpiece holder is exchanged for a dressing tool for dressing the mold is no longer necessary.

However, the main disadvantage remains with today's usual polishing processes (also when using the combination tools), that the lens to be processed after Polishing the first surface from the workpiece holder must be removed and rotated so that it into a second polishing machine with the corresponding mold for the second lens surface can. This process is time consuming and also involves the risk of damage to the already completed first lens surface.

So that the first, already finished lens surface when polishing the second surface not from the Workpiece holder is damaged, it must with a Protective varnish. Applying this lacquer is time consuming, as is later removal of the protective lacquer. There are also undesirable drying times and environmental problems when using solvent-based Paints. Furthermore, the application of layers of paint with a very homogeneous thickness with regard to lens accuracy is desirable, but in practice difficult to realize.

In today's methods for polishing lenses workpiece holders are used, which are essentially consist of a hollow cylinder made of plastic, which is adapted in its inner diameter to the lens is so that it can be inserted into it. Internally the hollow cylinder usually has a rubber membrane that can be pressurized and then lies flat against the lens. This will these pressed against the mold. Because of the special Properties and inaccuracies of the membrane this contact pressure between the lens and the mold seen above the surface with small irregularities afflicted. This is a disadvantage with the known devices for lens polishing that unfavorably on affects the lens accuracy.

Devices have also become known in which this membrane is dispensed with. Instead, lies the lens in the tool holder with her first Edge on a small bunch. When the The back of the lens with compressed air lifts it from it Bund off and is pressed against the mold. The Pressure distribution is now more even than this is the case when using a membrane but there are other disadvantages. Because air is compressible is the pressure of the lens on the mold not as stable as would be desirable. Moreover it comes through the air passing through the gap between The lens and workpiece holder flows to dry Polishing suspension on the edge of the lens, which is because of the required Cleaning effort is very disadvantageous. It is also unfavorable that the polishing result Insufficient frictional heat when working with compressed air can be dissipated so that the lens is uneven warmed, causing warpage due to thermal expansion and so that it can lead to inaccuracies.

The invention has for its object optical lenses less expensive and more precise to manufacture than this according to the prior art is possible so far.

This task is carried out in a method of the type mentioned at the beginning Kind solved in that the first workpiece holder is driven a second workpiece holder for polishing on both sides with drive opposite the first workpiece holder is positioned and the lens without turning into the second Pass the workpiece holder and from the side of the first Workpiece holder on the other side with one driven tool is polished.

In the method and the device according to the invention (Machine) to carry out the method at least avoided some of the aforementioned drawbacks.

So both sides of the lens are in one Machine polished. After the first polishing process the lens from the first workpiece holder without turning can be transported into the second workpiece holder. Here, the alignment of the lens to the machine be maintained with high accuracy. It is no tool change required because for the first Polishing a tool on one side of the lens can be kept ready while for polishing the second side a tool on the other side the lens is available. Since the two tools in the corresponding device can be present already positioned them there with high accuracy and be moved so that errors that occur in a Tool changes usually occur can be avoided can.

In a first embodiment, four spindles can be used be present, namely with two tool spindles Polishing tools and two combination spindles with combination tools, the workpiece holders and dressing tools included, or - in a second variant - there must be at least six spindles, namely two tool spindles with polishing tools, two workpiece spindles with workpiece holders and two dressing spindles with dressing tools.

Further advantageous configurations result from the subclaims.

The task is accomplished by a device of the beginning mentioned type solved in that for the bilateral Polishing an optical lens a second driven Tool spindle on which a second mold is arranged and a second driven workpiece spindle with a second workpiece acceptance, the first mold in a working position relative to the first workpiece holder, the first workpiece holder in a transfer position relative to second workpiece holder in which the two workpiece holders are aligned with each other, and the second Workpiece holder in a working position relative to second mold can be positioned and the two Molding tools on different sides of the lens Act.

This configuration ensures that the first Mold on which one side of the lens can act, to polish them while the second mold is on the other side of the lens can act to polish it. The change between the two machining processes takes place in that the lens from the first Transfer the workpiece holder into the second workpiece holder becomes. Because the two workpiece holders here are aligned to each other, the transfer can take place without turning or turning the lens got to. The molding tools can be done with high accuracy are positioned opposite the workpiece holders, because no tool changes are required.

Further advantages result from the subclaims.

The four-spindle version in the top and also a tool in the lower part of the polishing machine and a combination spindle arranged. The two combination spindles are in this case with the aforementioned Combination tool equipped that both a dressing tool, and also has a workpiece holder.

In the six-spindle version are in the upper and also in lower part of the polishing machine one tool, Workpiece and dressing spindle arranged. In this Case can be worked without the combination tool, i.e. the workpiece spindle is with a workpiece holder equipped while on the dressing spindle usual dressing tool is attached.

The text below takes on the four-spindle version Regarding, the same applies analogously to the Six spindle version.

In one of the variants of the device according to the invention there is a so-called in the upper part of the machine Swivel head that swiveled around the B axis can be arranged with the B axis horizontally is. On the swivel head are the combination spindles on the top and attached the tool spindle, both of which Axes are parallel, stand vertically in the rest position and lie in a plane that is perpendicular to the B axis is arranged. By swiveling the swivel head around the B axis can share the two spindles mentioned be tilted. You have one Drive with which they can be set in rotation.

There are also in the lower part of the machine a driven combination and a tool spindle, whose both axes are parallel, are vertical and are in the same plane as the two above lying spindles. The two spindles below are opposite the two top spindles swapped right-left, i.e. in pairs is always one Tool spindle of a combination spindle in the vertical direction seen, assigned.

The two spindles below are on one Z-slide attached, which allows vertical movements, which also causes the spindles in this direction can be adjusted. The Z slide in turn is attached to an X-slide, which allows horizontal movements perpendicular to the B axis perform. This makes it possible to see the two below traversing spindles in the X and Z directions.

In the six-spindle version, the two overhead spindles and the two spindles below A dressing spindle is assigned as the third spindle. From the feed carriage or the swivel head then the attached three spindles in the moved the same way as before with the four-spindle Machine described.

There are also further refinements of the invention Device provided. For example, B. the two overhead spindles (tool and combination spindles) be attached to its own swivel head, so that they are independent of each other from the vertical position can be swung out. Accordingly, would also the two spindles below (tool and Combi spindle) each attached to its own Z slide. Each of these two Z-slides would be on one separate X-slide attached. The one described here Arrangement of a total of two swivel heads and each would result in two X and two Z slides Possibility to polish two lenses at the same time, from which a significant cost saving, both at the labor and investment costs.

The directions "X", "Z" and "B" are for abbreviation purposes used. For the explanation here it should be assumed that the "X" direction is a Plane in the horizontal direction and the "Z" direction the plane spans in the vertical direction, while the "B" direction is perpendicular to this plane. Under Maintaining these directions relative to each other it is possible to change the absolute directions in space.

In the method according to the invention and in the device to carry out the procedure is further provided that the workpiece holder from a cup-shaped There is a hollow cylinder in its opening the edge of the lens is placed on a small collar becomes. So that the lens against the polishing tool (Mold) can be pressed, the interior the workpiece holder filled with polishing suspension and these are subjected to a selectable pressure. This hydrostatic Storage has a number of advantages which will be discussed later.

From the pressurized polishing suspension, the Then pressed lens against the mold and so the required polishing pressure is generated. The polishing slurry also emerges from the very fine gap between the lens and workpiece holder and arrives as desired, between the polishing surfaces of the mold and the surface of the lens to be polished.

The process sequence with the method according to the invention and the corresponding CNC-controlled device then including the various alternatives as follows:

First, the two molds are made one after the other dressed for what the swivel head from its zero position is swung out and by procedures in X - and Z axis either the combination tool (four spindle Version) or the dressing tool of conventional design (six-spindle version) with the molding tool in Is brought in contact after both spindle drives were started. The dressing process then runs, whereby very fine infeed movements in the Z direction become.

After finishing the dressing process on both molds the spindles are moved apart again and the first lens in the workpiece holder of the first workpiece spindle inserted. If with the combination tool has been trained, this will now either changed manually or automatically so that not now the ring edge with the grinding tools is more but the workpiece holder, a plastic ring with the aforementioned collar for holding the lens.

The polishing process then runs with an inclined Swivel head (with tool spindle and molding tool), after the lens and molding tool through process were brought into contact in the X and Z directions. The from the annular gap between the workpiece holder and the lens emerging polishing suspension is distributed in ideally between the polishing surfaces of the mold and the lens surface.

The above-mentioned disadvantages that arise when working result with air-loaded workpiece holders in the hydrostatic bearing proposed here avoided. Because the water-containing suspension is practical the lens becomes stable and incompressible pressed evenly against the mold. Through the good heat conduction and high specific heat of the water the lens on the front and back is very well chilled and thus the aforementioned undesirable Avoid heating the lens. Also cares the one constantly emerging from the said annular gap Suspension for the lens to get wet on the edges remains and there are no dried residues in this Can form area. Even when working with The disadvantages of a rubber membrane are avoided. Since no membrane is used, but the Presses liquid directly onto the back of the lens Inaccuracies due to inaccurate membrane pressure do not occur. The advantages of the invention mentioned here Procedures lead to an initial increase in quality and cost reduction in lens polishing.

If we speak of the workpiece holder in the following, it is always part of the combination tool in question.
A very significant advantage in the method according to the invention and the device for carrying out the method is that after the polishing of the first side, the lens can be transferred from the first workpiece holder to the second workpiece holder without manual intervention, where the polishing of the second side then takes place , For this purpose, the suspension in the first combination tool with workpiece holder is first depressurized and the tool and combination spindle are then moved apart in the Z direction. Then the swivel head is pivoted back to the zero position and the X and Z slide are moved so that the first combination spindle is arranged coaxially with the second, that is, that the axis of the first workpiece holder coincides with the axis of the second workpiece holder and the almost touch the two workpiece holders, ie stand as close to each other as possible. By pressurizing the polishing suspension in the first workpiece holder, the lens is hydraulically pressed out of this and pushed into the second workpiece holder.

The advantages are obvious and as follows:

It is particularly advantageous that the lenses on their polished on both sides on a single machine can be. The investment costs are corresponding lower, since a second machine can be omitted. Also the labor costs are significantly lower than for the State-of-the-art method since the Lens is polished on both sides without manual intervention and the shortest way from the first to the second workpiece holder arrives. Of particular note is that the lens when changing from the first Workpiece holder in the second can not be rotated must and no separate devices for this change required are. The lens comes from the first in the second workpiece holder exclusively with the help of machine parts, devices and control elements, which anyway for lens polishing and regardless of this change are required. The costs for the invention are correspondingly low Buffing machine which is a second buffing machine superfluous and also intermediate storage and Handling devices for changing the lenses saves.

Because the lenses after polishing the first side are not more manually from the workpiece holder of a first polishing machine in the workpiece holder of a second polishing machine must be placed so that the second Side can be polished and also no workpiece holders are used with rubber membranes Another major advantage is that there is no risk of damage on the first finished lens surface given is. For this reason, the application of the aforementioned protective varnish are eliminated. It there is no labor and investment for this step "apply protective lacquer". The same naturally applies to the "Remove protective lacquer" operation.

Further details on the method and the device for performing the method explained with reference to Figs. 1 to 3. It is assumed, that all machine functions are CNC controlled are. Only the basic principle is shown in the illustrations of the four machine spindles and their position in relation to each other shown. As with the four-spindle machine two combination tools are provided in the illustrations shown (dressing tool with integrated workpiece holder). In the case shown, the two are top spindles attached to a swivel head, which can be swiveled around the B axis while the two lower spindles with a feed system are connected, the movements in the X and Z direction allowed. The various are not shown Drive systems and other details.

In principle, however, other arrangements are also possible, in particular provision is also made to move the four spindles independently of one another in order to be able to polish two lens sides at the same time , again using combination tools.

The six-spindle polishing machine works in the same way and construction of the four-spindle shown here Machine. When running as a six-spindle Each machine would have the spindle for the dressing tool with the spindle for the workpiece holder on one common movement system.

In Fig. 1 the machine is - highly schematic - as Overview shown.

Fig. 2 shows the transfer of the lens from the bottom Workpiece holder to the upper one.

Fig. 3 shows the main processing steps in eight phases are shown.

To Fig. 1:

On a machine frame (1) is in the upper area Swivel head (2) pivoted about the B axis (3). The tool spindle I (4) is on the swivel head (2) attached to the die at its lower end I (5) for a convex lens surface. Also connected to the swivel head (2) Combined spindle II (6), at the lower end of which is the combination tool II (7) is attached.

In the lower area of the machine frame (1) is a X-slide (8) mounted so that it has horizontal movements can run perpendicular to the B axis (3). With a Z-slide (9) is connected to the X-slide (8), which enables vertical movements and the combination spindle I (10) and the tool spindle II (11). The combination tool is at the upper end of the combination spindle I (10) I (12) attached while at the top of the Tool spindle II (11) arranged the molding tool II (13) is. The combination tool I (12) consists of a inner part, the dressing tool I (16), with the combination spindle I (10) is connected and an external one Part, the workpiece holder I (14). Analogously to this the combination tool II (7) consists of an internal one Dressing tool II (17) with the combination spindle II (6) is connected and one outside Workpiece holder II (15).

To Fig. 2:

Fig. 2 shows how the lens to be machined (18) from the combination tool I (12) into the combination tool II (7) is transported. For this purpose, the combination spindle I (10) first by the method in the X axis exactly vertical under the combination spindle II (6) driven and then by moving the combination spindle I (10) in the Z axis reaches the workpiece holder I (14) and the workpiece holder II (15) almost touch. The dressing tool I (16) and the dressing tool II (17) are on the one hand with the combination spindle I (10) and on the other connected to the combination spindle II (6) and carry the the workpiece receptacles I (14) and Workpiece holder II (15).

The lens (18) is initially in the workpiece holder I (14) of the combination tool I (12). she will by pressurizing the filled with polishing suspension inner cavity (19) of the combination spindle I (10) and the interior (20) of the combination tool I (12) by means of hydraulic force in the workpiece holder II (15) of the combination tool II (7) pressed. In this process, the inner Cavity (21) of the combination spindle II (6) and thus also the interior (22) of the combination tool II (7) depressurized.

The lens (18) is thus in the polishing position for the second page.

A major advantage in the method according to the invention and the device for performing the method consists in the fact that the Leaking polishing suspension (18) is not harmful is because the polishing process with plenty of addition anyway expires from polishing slurry. The use of the same medium for the transport of the lens (18) from the workpiece holder I (14) in the workpiece holder II (15), pressing the lens (18) against the Molding tool I (5) or molding tool II (13) and this is an essential part of the polishing process itself Part of the present invention.

To Fig. 3:

This illustration shows the polishing of a lens (18) including dressing the mold I (5) and of the mold II (13) shown in eight phase images. For the sake of clarity, only those four spindles with the attached tools and the lens (18) drawn. Not shown in particular became the swivel head (2). When dressing the Forming tools (5) and (13) as well as during polishing the lens (18) becomes the axis of the spindles involved placed at an angle to each other, with the axis intersection at the center of curvature of the lens (18) or the molds (5) or (13) must lie.

Since the pictorial representations for space reasons were aligned with the frame (right u. left = equal distance to the boundary lines) the shift of the spindles from phase image to phase image as a relative distance to the drawn Axis cross.

Phase diagram 1 = basic position

Here is the basic position of the four spindles of the polishing machine shown.

Phase diagram 2 = dressing of forming tool I (5)

The workpiece holder was on the combination tool I (12) I (14) removed (manually or automatically) and thus the dressing tool I (16) is exposed. The Swivel head (2) was placed at an angle and thus also the tool spindle I (4) with the molding tool I (5). The dressing tool was made by moving in the X and Z directions I (16) in contact with the molding tool I (5) brought after the drives of the combination spindle I (10) and the tool spindle I (4) started in opposite directions were. By feeding the dressing tool I (16) in the Z direction becomes the desired material removal generated in the fine range.

Phase diagram 3 = dressing mold II (13)

The workpiece holder was on the combination tool II (7) II (15) removed (manually or automatically) and thus the dressing tool II (17) is exposed. The swivel head (2) was tilted in the other direction and thus also the combination spindle II (6). By procedure The molding tool was in the X and Z directions II (13) in contact with the dressing tool II (17) brought after previously the drives for the combination spindle II (6) and the tool spindle II (11) in opposite directions were started. By advancing the mold II (13) in the Z direction becomes the desired material removal generated in the fine range.

Phase image 4 = insert the lens (18) in the workpiece holder I (14)

The workpiece holder was on the combination tool I (12) I (14) and on the combination tool II (7) the workpiece holder II (15) reattached (manually or automatically). The swivel head was used for better handling (2) pivoted back to the zero position so that the axes of the tool spindle I (4) and the combination spindle II (6) stand vertically. Through procedures in X and The combination spindle I (10) with the Workpiece holder I (14) moved into one position, which allows the lens (18) to be inserted (by hand or automatically).

Phase image 5 = polishing the first, convex side from lens (18)

The swivel head (2) was tilted and thus also the tool spindle I (4) with the molding tool I (5). By moving in the X and Z directions the lens (18) in the workpiece holder I (14) Combi spindle I (10) in pressure-free contact with the Forming tool I (5) brought after previously the drives for the tool spindle I (4) and the combination spindle I (10) were started. Then the polishing suspension via the inner cavity (19) of the combination spindle I (10) in the interior (20) of the combination tool I (12) headed and pressurized. there puts the lens (18) on the mold I (5) and from the annular gap between the lens (18) and the polishing suspension emerging from the workpiece holder I (14) ensures the desired material removal during polishing. A feed movement of the machine spindle is not necessary because the lens (18) is from the polishing slurry steadily pressed towards mold I (5) becomes.

Phase image 6 = transport of the lens (18) from the Workpiece holder I (14) in the workpiece holder II (15)

The swivel head (2) was again placed vertically and thus also the tool spindle I (4) with the molding tool I (5) and the combination spindle II (6) with the combination tool II (7). The X-slide and the Z-slide were operated so that the combination spindle I (10) for Combined spindle II (6) is coaxially aligned, i.e. that the axis of the workpiece holder I (14) with the Axis of the workpiece holder II (15) coincides and the two workpiece holders (14) and (15) almost touch, i.e. at the smallest possible distance from each other stand. By pressurizing the inner cavity (19) the combination spindle I (10) and thus also the Interior (20) of the combination tool I (12) Hydraulic lens (18) from the workpiece holder I (14) out and into the workpiece holder II (15) pushed in.

Phase image 7 = polishing the second, concave side the lens (18)

The swivel head (2) was tilted and thus also the combination spindle II (6) with the combination tool II (7) and the workpiece holder II (15), the the lens (18) carries. Through procedures in X and The molding tool II (13) became unpressurized in the Z direction Bring contact with the lens (18) after previously the drives for the tool spindle II (11) and the combination spindle II (6) was started. Subsequently the polishing slurry over the inner cavity (21) the combination spindle II (6) into the interior (22) of the dressing tool II (17) and put under pressure. The lens (18) comes on the mold II (13) on and out of the annular gap between the lens (18) and the workpiece holder II (15) emerging polishing suspension ensures the desired material removal during polishing.

Phase image 8 = removal of the finished polished lens (18)

For better handling, the swivel head (2) was in the zero position is pivoted back so that the axes the tool spindle I (4) and the combination spindle II (6) stand vertically. By moving in the X and Z directions became the combination spindle I (10) and the tool spindle II (11) moved into a position in which the combination tool I (12) and the molding tool II (13) at removing (by hand or automatically) the lens (18) do not bother.

It is also envisioned that this is transported by the workpiece-receiving II (15) in the workpiece holder I (14) before the removal of the lens (18), so that the lens be removed (18) from the underlying workpiece holder I (14) can. This variant was not shown here.

Claims (19)

1. Method of polishing an optical lens (18), in which the lens (18) is arranged in a first workpiece holder (14) and is polished on a first side by a driven tool (5), characterised in that the first workpiece holder (14) is driven, a second driven workpiece holder (15) is positioned opposite the first workpiece holder (14) for polishing on both sides and the lens (18) is transferred to the second workpiece holder (15) without turning and polished on its other side by a driven tool (13) from the side of the first workpiece holder (14).
2. Method according to claim 1, characterised in that the lens (18) in the workpiece holder (14, 15) is pressed against a form tool (5, 13) by a pressurised polishing suspension.
3. Method according to claim 2, characterised in that the lens (18) is pressed out of the first workpiece holder (14) and into the second workpiece holder (15) by the pressurised polishing suspension.
4. Method according to one of claims 1 to 3, characterised in that the form tools (5, 13) used for polishing are dressed by dressing tools (16, 17), the means used to position the form tools (5, 13) relative to the workpiece holders (14, 15) also being used to position the dressing tools (16, 17) relative to the form tools (5, 13).
5. Method according to one of claims 1 to 4, characterised in that one workpiece holder (14, 15) is used as a support for a dressing tool (16, 17).
6. Method according to one of claims 1 to 5, characterised in that one workpiece holder (14, 15) and one form tool (5, 13) arranged on one side of the lens are moved together and one workpiece holder (15, 14) and one form tool (13, 15) arranged on the other side of the lens (18) are also moved together.
7. Method according to one of claims 1 to 5, characterised in that the two workpiece holders (14, 15) and the two form tools (5, 13) are moved independently of one another.
8. Device for polishing optical lenses (18) comprising a first driven tool spindle (4) on which a first form tool (5) is arranged and a first workpiece spindle (10) with a first workpiece holder (14), the first form tool (5) and the first workpiece holder (14) cooperating in a first working position, characterised in that a second driven tool spindle (11) on which a second form tool (13) is arranged and a second driven workpiece spindle (6) with a second workpiece holder (15) are provided fpr polishing an optical lens on both sides, wherein the first form tool (5) can be positioned in a working position relative to the first workpiece holder (14), the first workpiece holder (14) can be positioned in a transfer position relative to the second workpiece holder (15), in which the two workpiece holders (14, 15) are aligned relative to one another, and the second workpiece holder (15) can be positioned in a working position relative to the second form tool (13) and the two form tools (5, 13) act on different sides of the lens.
9. Device according to claim 8, characterised in that the first form tool (5) and the second workpiece holder (15) are arranged in one part of a machine (1) and the second form tool (13) and the first workpiece holder (14) are arranged in another part of the machine (1), the two parts being situated on different sides of one plane.
10. Device according to claim 8 or claim 9, characterised in that at least one of the workpiece spindles is in the form of a combination spindle (6, 10), in which the workpiece holder (14, 15) is placed on a dressing tool (16, 17).
11. Device according to one of claims 8 to 10, characterised in that the combination tool (12, 7) can be switched from dressing operation to polishing operation, a cutting edge of the corresponding dressing tool (16, 17) projecting towards the front during the dressing operation, while the workpiece holder (14, 15) is arranged in the front part during the polishing operation.
12. Device according to one of claims 8 to 10, characterised in that, in addition to the first and second tool spindles and workpiece spindles (4, 11, 6, 10), a first dressing spindle is provided in one part of the machine (1) for dressing the second form tool (13) and a second dressing spindle is provided in the other part of the machine (1) for dressing the second form tool (13).
13. Device according to one of claims 8 to 12, characterised in that the spindles (4, 6) of one part can swivel relative to the spindles (10, 11) of the other part and can be displaced along a first axis (X) and along a second axis (Z).
14. Device according to one of claims 8 to 13, characterised in that the spindles (4, 6; 10, 11) arranged in one part of the machine frame (1) are each arranged on a common moving device (2, 9).
15. Device according to claim 14, characterised in that one moving device (2) is in the form of a swivel head which can swivel about an axis (3) and the other is in the form of a slide (9).
16. Device according to one of claims 10 to 13, characterised in that the tool spindle and the combination spindle or the workpiece spindle and the dressing spindle are each arranged on their own moving device.
17. Device according to one of claims 10 to 16, characterised in that the combination spindles (10, 6) are each provided with an inner hollow space (19, 21) connected to an inner space (20, 22) of the respective combination tool (12, 7) and that these hollow spaces and inner spaces (19-22) can be filled with possibly pressurised polishing suspension.
18. Device according to claim 17, characterised in that the pressure of the polishing suspension at opposing workpiece holders (14, 15) can be brought to a pressure sufficient to transfer the lens (18) from one workpiece holder (14, 15) to the other.
19. Device according to one of claims 8 to 18, characterised in that the dressing tools (16, 17) are in the form of pot-type tools (cup shape).

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