Device for producing microstructures

1. A device for producing microstructures, comprising:

a spindle which can be rotated about a longitudinal axis thereof;

a fixture provided on said spindle for clamping a workpiece;

a linear drive adapted to produce a linear feed motion in a first direction;

an actuator arranged on said linear drive;

wherein said actuator comprises:

a fast drive for driving a tool in an axial direction substantially perpendicular to a workpiece surface by generating a fast advancing motion of said tool in the axial direction;

a guide mechanism coupled at a first axial end to said fast drive and at a second axial end to said tool and configured to allow feeding of the tool in the axial direction of said fast drive, and to substantially resist movement of said tool in a plane perpendicular to the axial direction; and

an attenuator coupled to said guide mechanism for damping axial movement of said fast drive;

wherein said guide mechanism further includes biasing means for generating a restoring force acting against said advancing motion and said guide mechanism comprises a ram disposed in a sealed cavity and movably supported within a housing against said restoring force, and further wherein said ram is biased against said fast drive by a fluid pressure.

2. The device of claim 1 , wherein said fast drive is configured as a piezo drive.

3. The device of claim 1 , wherein said guide mechanism has a static rigidity of at least 100 N/μm, in a plane perpendicular to an axial direction of said guide.

4. The device of claim 1 , wherein said ram is supported by first and second spring elements, said spring elements being substantially unyielding in a radial direction of said ram, while allowing deflection in an axial direction of said ram against a spring force of said spring elements.

5. The device of claim 4 , wherein said spring elements are configured as leaf springs that have lengthwise ends clamped in holders and that can be moved substantially transversely to a plane wherein said leaf springs extend.

6. The device of claim 5 , wherein said spring elements are configured as feeler gauge strips that are clamped in radial direction in crossed arrangement between said holders and said ram.

7. The device of claim 4 , wherein said spring elements are configured as disk springs.

8. The device of claim 1 , wherein said fast drive further comprises:

a housing,

a pressure-tight space formed within said housing and being sealed in said axial direction by a first diaphragm connected with said ram at said first axial end, and by a second diaphragm connected with said ram at said second axial end;

wherein a fluid pressure can be applied to said pressure-tight space; and

wherein said first diaphragm has a larger surface exposed to said fluid pressure than has said second diaphragm.

9. The device of claim 8 , wherein said attenuator is disposed in said pressure-tight space within said housing and comprises a sintered material comprising an open porosity; and

wherein a gap being filled with a damping medium is formed between said attenuator and said first diaphragm.

10. The device of claim 1 , wherein a first end of said fast drive opposite said ram is clamped on a holding fixture, and wherein a second end of said fast drive, opposite the first end, is coupled with said ram via a compensating element configured for compensating alignment errors between a longitudinal axis of said ram and a longitudinal axis of said fast drive.

11. The device of claim 1 , further comprising a controller for controlling a movement of said actuator, said controller being configured for controlling movement of said actuator relative to a workpiece in response to an angular position of said workpiece and a position of said actuator along a feed direction of said linear drive.

12. The device of claim 11 , wherein said controller comprises means for transforming a specified microstructure to be produced on the workpiece into a coordinate-transformed structure defined by polar coordinates, which contains actuation values for said actuator as a function of an angle of rotation of said workpiece and a linear feed of said linear drive in a direction along a workpiece surface.

13. The device of claim 12 , wherein said controller comprises means for transforming a specified microstructure to be produced on the workpiece, defined by Cartesian coordinates, to a coordinate-transformed structure defined by polar coordinates, where said actuation values for said actuator are stored as a function of polar coordinates which contain an angle of rotation of said workpiece and a radial distance of said fast tool from an origin of the polar coordinate system.

14. The device of claim 12 , wherein the coordinate-transformed structure is stored in a look-up table LUT, from which said electronic controller derives an actuation signal that is supplied to an amplifier for driving the actuator.

15. The device of claim 14 , wherein said controller comprises means for interpolating the actuation signal supplied to the amplifier as a function of position increments of the linear feed motion of said linear drive.

16. A device for producing microstructures, comprising:

a spindle which can be rotated about a longitudinal axis thereof;

a fixture provided on said spindle for clamping a workpiece;

an linear drive adapted to produce a linear feed motion in a first direction;

an actuator arranged on said linear drive;

wherein said actuator comprises:

a fast drive for driving a tool in an axial direction substantially perpendicular to a workpiece surface by generating a fast advancing motion of said tool in the axial direction;

a guide mechanism coupled with said fast drive and said tool and configured to allow feeding of the tool in the axial direction of said fast drive, and to substantially resist movement of said tool in a plane perpendicular to the axial direction;

wherein said guide mechanism further includes biasing means for generating a restoring force acting against said advancing motion; and

a controller for controlling a movement of said actuator, said controller being configured for controlling movement of said actuator relative to a workpiece in response to an angular position of said workpiece and a position of said actuator along a feed direction of said linear drive;

wherein said actuator has a first resonant frequency of at least 1500 Hz; and wherein said controller is configured for generating a filtered signal for driving said actuator, said filtered signal being selected from the group formed by a low-pass filtered and a band-pass filtered signal, said filtered signal having an upper cut-off frequency being lower than a resonant frequency of said actuator.

17. An actuator for driving a tool relative to a workpiece that is rotatably mounted on a turning machine for the purpose of producing a microstructured surface, said actuator comprising:

a housing;

a fast drive arranged in said housing for generating a fast advancing motion in an axial direction to drive the tool in said axial direction, said fast drive being coupled to said tool via a ram that is connected at a first axial end to said fast drive and at a second axial end to said tool, said ram being supported within said housing by a guide mechanism that is coupled to said ram and configured to allow movement of the ram in the axial direction and resist movement of the ram in a plane perpendicular to the axial direction, wherein said ram is disposed in a sealed cavity within said housing, said sealed cavity being provided with pressurized fluid for biasing said ram against said advancing motion of said fast drive.

18. The actuator of claim 17 , wherein said sealed cavity is defined by a first diaphragm disposed at said first axial end of said ram and a second diaphragm disposed at said second axial end of said ram.

19. The actuator of claim 18 , wherein the first diaphragm has a larger surface area exposed to said fluid pressure than said second diaphragm.

20. The actuator of claim 17 , further including an attenuator for damping axial movement of said fast drive.

21. The actuator of claim 20 , wherein said attenuator is disposed within said sealed cavity for damping axial movement of said ram to thereby dampen axial movement of said fast drive.

22. The actuator of claim 17 , wherein said guide mechanism includes biasing means for generating a restoring force against said advancing motion.

23. The actuator of claim 22 , wherein said biasing means comprises first and second spring elements that are coupled to said first and second axial ends, respectively, of said ram, said spring elements being substantially unyielding in the plane perpendicular to said axial direction while allowing deflection thereof, and movement of the ram, in the axial direction against the spring force of said spring elements.