DE102007020633B4 - positioning - Google Patents

Abstract

Positioning device, in particular chuck for a machine tool, with
(a) a base body (12),
(b) a driven body (14) arranged in front of the main body (12) with respect to a longitudinal axis (1) for connection to a workpiece (56),
(C) one connected to the base body (12) and along the longitudinal axis (L) extending connecting element (16) and
(D) at least two on the base body (12) attached, transversely to the longitudinal axis (L) acting eccentric actuators (18) which are adapted to move the output body (14) perpendicular to the longitudinal axis (L) relative to the base body (12) by elastic Deforming the connecting element (16),
characterized in that
(E) the positioning device (10) has at least two tilting actuators (36) for tilting the output body (14) relative to the base body (12).

Description

The The invention relates to a positioning device, in particular a Chuck for a machine tool, with a base body, one with respect to a longitudinal axis in front of the main body arranged output body for connecting to a workpiece, one with the main body connected and extending along the longitudinal axis connecting element and at least two on the body fastened, transverse to the longitudinal axis acting eccentric actuators, in particular eccentric piezoelectric actuators, the are formed for displacing the output body perpendicular to the longitudinal axis relative to the main body by elastically deforming the connecting element. According to one In the second aspect, the invention relates to a method of alignment a workpiece.

From the DE 854 759 B a device for clamping workpieces for machine tools is known, in which an adjustable in two mutually perpendicular planes three-jaw chuck is used to allow an axially parallel adjustment the tensioned tool. A disadvantage of the known device that the axis-parallel alignment is only possible manually and requires a lot of time.

From the DE 103 60 917 A1 is a tool holder for a rotatable about a rotation axis tool known. The tool holder has a clamping shaft, on whose circumference electrostrictive material is arranged, which can be excited externally during rotation of the tool holder, so that Torkelschwingungen be avoided. A disadvantage of the tool holder is that larger geometrical deviations can not be corrected with this tool holder.

From the DE 41 27 770 A1 a mandrel for cutting tools is known in which adjusting elements are present to align a tensioned with the mandrel tool. A disadvantage of this mandrel is that the alignment of the tool piece with it is very labor-intensive and can only be done manually.

From the DE 38 24 462 C2 For example, a tool adjusting device is known which serves to set up an axis of a stationary tool on a spindle axis of a moving workpiece. A disadvantage of this device is that it is only complicated and manually adjustable.

Of Further are generic positioning devices known. These are for example in the preparation of forged raw gears for a subsequent Grinding used. After forging and a subsequent one hardening It can indeed happen that a central bore of the raw gear eccentric to its sprocket is arranged. Would be at the subsequent Schleifbe processing the raw gear on the Excentric central bore tense, one would depend on Abraded from the position on the sprocket varying amount of material be to the desired To obtain final contour, which is disadvantageous. Therefore, to avoid unnecessary oversize becomes before grinding in a hard turning process the central hole designed to be as possible low amount of material must be sanded.

To becomes the basic body the positioning device on a work spindle of a hard turning machine attached. Subsequently is the gear with a arranged on the output body tensioning device strained and geometrically measured. Then the clamping device so relative to the main body moved in parallel, that a rotation axis of the work spindle of the Hard turning machine through the center of the central hole to be introduced runs. Subsequently, the central hole is turned out, leaving the raw gear only minimally finished in the subsequent grinding process must become.

adversely on the known positioning device is that they only for narrow gears suitable is. It has become shown that the chuck for deeper components, such as pinion shafts or wide gears, unsuitable is.

Of the Invention is based on the object, a positioning device to propose that overcomes the disadvantages of the prior art.

The Invention solves the problem by a generic positioning device, the at least two tilting actuators, in particular tilting piezoelectric actuators, has, which is formed for tilting the drive body relative to the base body and are arranged. The invention also solves the problem a machine tool, in particular a grinding or lathe, a workpiece turning device for turning a workpiece has an axis of rotation and a positioning device according to the invention, the longitudinal axis the positioning device coincides with the axis of rotation. According to one second aspect triggers the invention solves the problem by a method for aligning a workpiece the step of a clamping of the workpiece on a machine tool according to the invention includes.

An advantage of the invention is that wobble errors of a workpiece, such as a raw gear or a raw pinion shaft, are compensated. This also makes longer components le exactly aligned to a rotation axis of a machine tool. As a result, less material removal is needed so that oversizes can be reduced, grinding wheel wear is reduced, and faster and less expensive manufacturing can be achieved.

Thereby, that with the positioning device according to the invention Eccentric and tumbling error can be corrected, manufacturing errors in leading Processes are corrected. Committee is thus diminished. It has surprisingly pointed out that such a positioning device interpretable is that occurring when machining a tensioned workpiece machining forces can be safely intercepted, so that with the positioning device according to the invention essentially the same manufacturing tolerances can be maintained as with a conventional one Positioning chuck without actuators.

Advantageous is also that two components to be joined very precise can be aligned with each other. So it is possible an optical component, such as a lens or a lens assembly in an oversized To fix pipe. Around an optical axis of the optical component to a longitudinal axis to align the pipe, this must only with a positioning device according to the invention be clamped on a lathe. Subsequently, a possible deviation the optical axis from the longitudinal axis of the tube compensated by means of the positioning device and the Pipe will be afterwards in an external turning process finished. In this way, the optical axis of the optical Component in a simple manner to the longitudinal axis of the so finished Aligned pipe.

in the In the context of the present description, the term of the longitudinal axis in particular on an axis about which the positioning device is rotatable is formed by, for example, a corresponding recording for connection to a workpiece spindle a machine tool is provided. It is thereby on the rest position the actuators turned off, allowing an actuation of the eccentric actuators or tilt actuators the longitudinal axis not changed.

When Eccentric actuators or tilt actuators come next to piezo actuators, for example magnetostrictive actuators or electric motors using a threaded spindle are considered.

In a preferred embodiment the connecting element comprises a core in which the at least two tilt piezo actuators run parallel to the longitudinal axis. To this Way is the correction of the eccentric error of the correction of the tumble error separated. By controlling the eccentric actuators of the eccentric error be corrected without causing the wobble deviation of the workpiece from the longitudinal axis affected. Conversely, you can operated the tilt actuators without this being the eccentricity of the workpiece relative changes to the longitudinal axis.

Prefers The connecting element comprises a clamping element which is in a foot point with the output body connected and disposed between the tilting piezoelectric actuators, wherein the clamping element and the tilting piezoelectric actuators are arranged so that a lengths one of the tilting piezo actuators and shortening all other tilting piezo actuators for Tilting the output body relative to the main body leads. The clamping element may be for example a clamping screw, the passing through a bore in the core and engages the body and in this way, in particular those required for the actuators Preload applies.

It It is advantageous that the tilting piezoelectric actuators via conical ball and socket joints with the output body and / or the main body keep in touch. It becomes a particularly simple arrangement receive.

Prefers four tilt piezo actuators are provided, each in a force application point the output body attack, wherein the force application points a rhombus, in particular to form a square. By a symmetrical arrangement like this, the control of the tilting piezo actuators is facilitated. simultaneously is the influence of thermal expansion of the components of Positioning device relative to the position of the drive body to the basic body minimized, so that a corresponding compensation is unnecessary.

Especially Therefore, the base in the is preferred geometric center of the diamond or the square arranged. If more than four tilt piezoactuators are present, they are preferred in pairs opposite each other arranged and attack in respective force introduction points, the same distances from the bottom own, that is, with respect to one Direction of action of the tilting piezoelectric actuators lie in one plane. Cheap is In addition, if the force application points on the vertices of a regular polygon lie.

Preferably, the base body has a base ring and a base member membrane attached to the base ring, which has a relative to the base ring reduced flexural rigidity and on which the connecting element is arranged. The eccentric piezoelectric actuators favorably attack the base ring in this case. The bending stiffness of the main body membrane is preferably substantially smaller than the bending strength the connecting element, whereby a positioning device which is particularly easy to control is obtained.

Prefers has the output body an eccentric ring and includes a fixed to the eccentric ring Output body membrane, which has a relative to the eccentric ring reduced bending stiffness and where the connecting element is arranged. In this way, the Base ring and the eccentric ring to each other in parallel displaceable be stored so that a press the eccentric actuators to a parallel shift between base ring and eccentric ring leads and so the eccentric error independently is compensated by the wobble error. Such a positioning device is very easy to control.

According to one another embodiment Is it possible, that the connecting element is connected to the eccentric body, the Base body stored and by means of the eccentric piezo actuators in parallel displaceable relative to the main body ver is slidable, wherein the driven body mounted pivotally mounted on the eccentric body is.

Prefers while the output body has a foot section and a head portion for connecting to the workpiece, wherein the at least two tilt piezoactuators on the eccentric body are arranged, transverse to the longitudinal axis run and so to the foot part are arranged that a lengths one of the tilting piezoelectric actuators and shortening the other tilting piezo actuators to a tendency of the output body relative to the eccentric body leads. It is possible in this way that the eccentric piezo actuators are parallel to the tilt piezo actuators run, resulting in a particularly compact design for the positioning results. It is also advantageous that all piezoelectric actuators arranged so can be that they always have a perfectly stretched arrangement and no bending forces to act on them. This increases their service life.

In a preferred embodiment the tilt piezo actuators are arranged in antagonist arrangement and are substantially perpendicular to the longitudinal axis. Under an opponent arrangement is to be understood in particular that two actuators each other have exactly opposite acting directions of action, which also in a common plane. Become both actors of the opponent pair pressed simultaneously, so it comes only to a pressure, but no shear stress on acted upon component. The advantage of this is the special easy controllability of the actuators.

Especially Cheap is when the output body adjacent to its head portion from the driven body diaphragm is held. In this case, the output body with the help of tilt actuators to pivoted a pivot point which is close to a workpiece facing face the output body lies. On the front surface can For example, arranged a clamping device for clamping the workpiece be such as a jaw or diaphragm chuck. If the tensioner is air actuatable, the positioning device has prefers one the longitudinal axis surrounding compressed air channel, which runs from the main body to the clamping means. Thereby compressed air can be directed from a machine tool to the clamping device become.

Around personnel to minimize within the positioning, is in accordance with a preferred embodiment provided an electrical control, which is designed to each to control two piezoactuators arranged in opposing arrangement, that one of the piezo actuators lengthens by a predetermined amount and the other piezoelectric actuator shortens by the same amount. So The forces exerted by the piezo actuators forces are reduced to the minimum.

A inventive machine tool according to the invention preferably has a measuring device for detecting a position of a with the positioning device tensioned workpiece. This situation can be, for example indicated relative to a coordinate system of the machine tool be. With the help of this measuring device, the position of the workpiece is detected and it may be the optimal location of, for example, a central well of the workpiece be determined. The necessary change in position of the workpiece is then over the eccentric actuators and the tilt actuators compensated. Under the Position of the workpiece In addition to its position in the x-, y- and z-direction, its orientation with respect to two becomes or three spatial direction angles understood.

One inventive method preferably comprises the steps of detecting a position of the positioning device relative to the machine tool, detecting a machining force on the workpiece and a driving of the eccentric and / or tilt piezoelectric actuators so that she a deflection of the workpiece due to the processing power reduce or compensate. The Processing power can be read from a table, for example become. Alternatively, the machining force may be from a force sensor can be detected, which is arranged on a tool holder of the machine tool is. It is also possible the machining power, for example, from a grinding wheel on the workpiece is applied to determine from the power of an engine that the grinding wheel drives.

in the Below are embodiments of the Invention with reference to the attached Drawings closer explained. It shows

1 a perspective view of a positioning device according to the invention according to a first embodiment,

2 a longitudinal section through the positioning device according to 1 .

3 a cross section perpendicular to the longitudinal direction by the positioning device according to 1 .

4 a perspective view of the positioning according to 1 .

5 a schematic representation of the operation of the positioning device according to the preceding figures,

6 an alternative embodiment of a positioning device according to the invention in a section along the longitudinal axis,

7 a perspective partial view of the positioning device according to 6 .

8th a perspective view of a detail of the positioning device according to the 6 and 7 .

9 a second view of the detail after 9 .

10 a longitudinal section through the detail according to the 8th and 9 and

11 a detailed view of the output body of a positioning device according to the invention.

1 shows a partial exploded view of a positioning device 10 that have a basic body 12 , one with respect to a longitudinal axis L in front of the main body 12 arranged output body 14 , one with the main body 12 connected and extending along the longitudinal axis L connecting element 16 and four at the base 12 fixed, extending transversely to the longitudinal axis L eccentric piezoelectric actuators 18.1 . 18.2 . 18.3 and 18.4 includes, which are arranged in antagonist arrangement. This means that they face each other in pairs, their directions of action run in one plane and on opposite sides of the connecting element 16 attack.

The main body 12 includes, as the longitudinal section H through the longitudinal axis L according to 2 shows a base ring 20 whose longitudinal axis coincides with the longitudinal axis L of the positioning device, and one on the base ring 20 attached main body membrane 22 , which is also substantially circular in shape and whose center lies on the longitudinal axis L. The main body membrane 22 shows in comparison to the base ring 20 a significantly reduced flexural rigidity, which is smaller by a factor of 100, for example. The connecting element 16 is at the body membrane 22 attached, for example screwed or welded.

The eccentric piezoelectric actuators 18.1 to 18.4 are at the base ring 20 attached and act as exemplified in 2 for the eccentric piezoelectric actuators 18.2 and 18.4 shown on the connecting element 16 one. For example, the eccentric piezoelectric actuator lasts 18.2 and shortens the eccentric piezoelectric actuator 18.4 , so deforms the connecting element 16 as in 2 indicated and the output body 14 shifts parallel to the base ring 20 , He is on schematically drawn elastokinematic grid guides 26 at the base ring 20 attached.

3 shows a cross section through the positioning device 10 that by the eccentric piezoelectric actuators 18.1 to 18.4 is drawn. The eccentric piezoelectric actuators are in respective receiving sleeves 28.1 to 28.4 arranged and act on a core 30 of the connecting element 16 , All eccentric piezoelectric actuators are accommodated in the same way in the respective receiving envelope. For example, the Exzen ter piezoelectric actuator 18.1 via a first conical cup-ball joint 32a on the receiving sleeve 28.1 and an identical conical cup-spherical disc joint 32b at the core 30 stored. At the core 30 are four longitudinal holes 34.1 , ..., 34.4 introduced, in each of which a tilting piezoelectric actuator 36.1 . 36.2 , 36.3 respectively. 36.4 fitted with little play.

Between two receiving sleeves each a fixing plate is mounted, for example, is located between the receiving sleeves 28.1 and 28.2 the fixing plate 38.1 which has a screw not shown with a clamping ring 40 connected to the core 30 surrounds without play. About the fixing plates 38.1 to 38.4 , the respective screws and the clamping ring 40 can the receptacles 28.1 to 28.4 to the core 30 pretensioned and the drive body are pre-adjusted. After adjustment, the receiving sleeves 28.1 to 28.4 , via screws with the base ring connected conclusively. The tilting piezo actuators 36.1 ., ..., 36.4 are provided in a square arrangement in the middle of a longitudinal bore 34.5 through the core 30 runs, in which a in 2 invisible preload screw 42 runs.

4 shows the preload screw 40 , which are located at a foot F on the output body 14 attack and do it with the core 40 combines. As 2 shows is a driven body membrane 44 concentric with an eccentric ring 46 arranged, both part of the output body 14 are. The output body diaphragm 44 provides a connection between the output body 14 and the eccentric ring 46 her and is between the output body 14 and the core 40 arranged. The tilting piezo actuators 36.1 . 26.2 . 36.3 . 36.4 engage in respective force introduction points K1, K2, K3 and K4, which form a square whose center of gravity coincides with the base point F.

5 shows the principal effect of the tilt piezo sensors on the output body membrane 44 , For example, is the tilting piezoelectric actuator elongated? 36.2 and shortens the tilting piezoelectric actuator 36.4 by the amount δI, the output body diaphragm tilts 44 relative to the main body 12 , Because the two tilt piezo actuators 36.2 . 36.4 be controlled so that they extend or shorten by the same amounts, the length of the preload screw remains 42 constant.

6 shows an alternative embodiment of a positioning device according to the invention 10 with the main body 12 , the output body 14 , the connecting element 16 and the receiving sleeves 28.3 and 28.4 ., In which not concealable the corresponding eccentric piezoelectric actuators are arranged.

6 also shows an eccentric body 48 using elastokinematic grid guides 26 at the base body 12 is mounted parallel displaceable. The output body 14 has a head section 50 , which has an end face for mounting a tensioning device 52 owns, and a foot section 54 , to attack the four tilt piezo actuators, of which in 6 the two tilt piezo actuators 36.1 and 36.3 are drawn. The output body 14 becomes adjacent to his headboard 50 from the output body diaphragm 44 supported. A length of the tilting piezoelectric actuator 36.1 and shortening the tilt piezoactuator 36.3 leads to a tilting of the output body 14 about a pivot D.

In 6 is also an adapter flange 58 to be recognized, which is adapted to work with a workpiece spindle 60 a machine tool, such as a lathe to be connected. The adapter flange 58 includes part of an interface 62 , with whose help electrical energy for the eccentric and tilt piezo actuators 18 respectively. 36 is transmitted. Control signals for the eccentric and tilt piezo actuators 18 respectively. 36 are transmitted over a radio link that is established according to the Bluetooth standard.

7 shows a perspective view of the positioning device according to 6 in which the output body 14 has been omitted for clarity.

8th shows a perspective view from below of the output body 14 with his foot section 54 on which the tilt piezo actuators 36.1 to 36.4 act, which are included in corresponding receptacles. The receiving sleeves are on the eccentric ring 46 attached. The in 8th invisible head portion of the output body is on the output body membrane 44 attached, allowing an actuation of the tilting piezo actuators 36 to a pivoting of the output body 14 leads.

9 time the attachment of the output body 14 on the output body membrane 44 in a perspective view

10 shows a cross section through the eccentric body 48 , the two in antagonist arrangement against the foot section 54 the output body 14 acting tilt piezo actuators 36.1 and 36.3 lets recognize. If, for example, the tilting piezoelectric actuator 36.1 lengthens and the tilting piezoelectric actuator 36.3 shortened, then the head section 50 the output body 14 against the driven body membrane 44 pressed and pivots about the pivot point D by a pivot angle φ relative to the longitudinal axis L. In this case, the output body diaphragm deforms 44 , but does not move relative to the eccentric ring 46 ,

In 11 is a workpiece 56 shown with the help of the tensioning device 52 on the output body 14 is curious.

The Positioning device according to the invention can for example be used to an optical component as a lens or lens assembly in a tube is precisely aligned to arrange. This will be first a raw tube made with an oversize, this means, it has a diameter larger than that for the finished one Tube target diameter. The following is the optical component arranged in an interior of the raw tube, to a longitudinal axis aligned and fixed there.

However, this alignment inevitably involves an error. To correct this error, the green tube is clamped with a positioning device as described above attached to a work spindle of a lathe. In this case, the raw tube is clamped so that its longitudinal axis is aligned as well as possible with a rotation axis of the work spindle. Subsequently, with a suitable measuring device, a deviation of the optical axis of the optical component relative to the rotation Determined axis of the work spindle and the positioning device is actuated so that both match as closely as possible. Subsequently, the raw tube is finished by external longitudinal turning. It is thus obtained a tube whose longitudinal axis coincides with high accuracy with the optical axis of the optical component. Said method, like all methods according to the invention, can also be carried out with two positioning devices according to the invention, which engage at opposite ends of the workpiece.

10

positioning

12

body

14

wear body

16

connecting element

18

Eccentric piezo actuator

20

base ring

22

Base membrane

24

shell

26

elasto channeling

28

receiving sleeve

30

core

32a, b

Conical seats Ball disc hinge

34

longitudinal bore

36

Tilt piezo actuator

38

fixing

40

tension

42

preloading screw

44

Output body membrane

46

eccentric

48

eccentric

50

header

52

jig

54

foot section

56

workpiece

58

adapter flange

60

Workpiece spindle

62

Radio interface

L

longitudinal axis

F

nadir

K

Force application point

D

pivot point

Claims (26)

Positioning device, in particular chuck for a machine tool, with (a) a basic body ( 12 ), (b) one with respect to a longitudinal axis ( 1 ) in front of the main body ( 12 ) arranged output body ( 14 ) for connecting to a workpiece ( 56 ), (c) one with the main body ( 12 ) and extending along the longitudinal axis (L) connecting element ( 16 ) and (d) at least two on the main body ( 12 ), transversely to the longitudinal axis (L) acting eccentric actuators ( 18 ), which are designed to move the output body ( 14 ) perpendicular to the longitudinal axis (L) relative to the main body ( 12 ) by elastically deforming the connecting element ( 16 ), characterized in that (e) the positioning device ( 10 ) at least two tilting actuators ( 36 ) for tilting the output body ( 14 ) relative to the main body ( 12 ) owns. Positioning device according to claim 1, characterized in that the tilting actuators Neige piezo actuators ( 36 ) are. Positioning device according to claim 2, characterized in that the connecting element ( 16 ) a core ( 30 ), in which the at least two tilting piezoelectric actuators ( 36 ) parallel to the longitudinal axis (L). Positioning device according to claim 3, characterized in that the connecting element ( 16 ) a tensioning element ( 42 ), which in a base point (F) with the output body ( 14 ) and between the tilting piezoelectric actuators ( 36 ) is arranged, wherein the clamping element ( 42 ) and the tilting piezoelectric actuators ( 36 ) are arranged so that a length of one of the tilting piezoelectric actuators ( 36 ) and a shortening of all other tilting piezo actuators ( 36 ) for tilting the output body ( 14 ) to the main body ( 12 ) leads. Positioning device according to one of claims 2 to 4, characterized by four tilting piezoelectric actuators ( 36 ), each in a force application point (K) on the output body ( 14 ), wherein the force introduction points (K) form a rhombus, in particular a square. Positioning device according to claim 5, characterized in that that the foot point (F) is arranged in the geometric center of the rhombus. Positioning device according to one of the preceding claims, characterized in that the basic body ( 12 ) a base ring ( 20 ) and one at the base ring ( 20 ) attached main body membrane ( 22 ), which is a relative to the base ring ( 20 ) has reduced flexural rigidity and at which the connecting element ( 16 ) is arranged. Positioning device according to one of the preceding claims, characterized in that the driven body ( 14 ) an eccentric ring ( 46 ) and one on the eccentric ring ( 46 ) attached output body membrane ( 44 ), which has a relative to the eccentric ring ( 46 ) has reduced flexural rigidity and at which the connecting element ( 16 ) is arranged. Positioning device according to one of claims 7 or 8, characterized in that the Ex Center Piezo Actuators ( 18 ) are arranged between the main body membrane ( 22 ) and the driven body membrane ( 44 ) on the connecting element ( 16 ) to act. Positioning device according to one of claims 8 or 9, characterized in that the eccentric ring ( 46 ) parallel displaceable on the base body ( 12 ) is stored. Positioning device according to claim 2, characterized in that the connecting element ( 16 ) with an eccentric body ( 48 ) connected to the main body ( 12 ) and by means of the eccentric piezoelectric actuators ( 18 ) parallel relative to the main body ( 12 ) is displaceable, and that the output body ( 14 ) pivotally mounted on the eccentric body ( 48 ) is stored. Positioning device according to claim 11, characterized in that the driven body ( 14 ) a foot section ( 54 ) and a head section ( 50 ) for connecting to a workpiece ( 56 ), wherein the at least two tilting piezoelectric actuators ( 36 ) on the eccentric body ( 48 ), transverse to the longitudinal axis (L) and so to the foot section ( 54 ) are arranged such that a length of one of the tilting piezoelectric actuators ( 36 ) and a shortening of the other tilting piezoelectric actuators ( 36 ) to a tilting of the output body ( 14 ) relative to the eccentric body ( 48 ) leads. Positioning device according to claim 12, characterized in that the eccentric body ( 48 ) four counter-rotating Neige piezo actuators ( 36 ), which are arranged substantially perpendicular to the longitudinal axis (L). Positioning device according to one of claims 11 to 13, characterized in that the output body ( 14 ) adjacent to its head section ( 50 ) from the driven body membrane ( 44 ) is held. Positioning device according to one of the preceding claims, characterized in that the basic body ( 12 ) is adapted to be connected to a work spindle of a machine tool, in particular a grinding or lathe. Positioning device according to one of the preceding claims, characterized by four eccentric piezoelectric actuators ( 18 ) arranged in antagonist arrangement. Positioning device according to one of the preceding claims, characterized in that on the driven body ( 14 ) a tensioning device ( 52 ), in particular a jaw or diaphragm chuck, for clamping the workpiece ( 56 ) is attached. Positioning device according to one of claims 10 to 16, characterized by an electrical control, which is designed in each case to have two piezoactuators (FIG. 18 . 36 ) so that one of the piezo actuators ( 18 . 36 ) lengthens by a predetermined amount and shortens the other piezoelectric actuator by the same amount. Machine tool, in particular a grinding machine or lathe, with (a) a workpiece turning device for rotating a workpiece ( 56 ) about an axis of rotation and (b) a positioning device according to any one of the preceding claims, wherein (c) the longitudinal axis (L) of the positioning device ( 10 ) coincides with the axis of rotation. Machine tool according to claim 19, characterized by a measuring device for detecting a position of a tensioned with the positioning workpiece ( 56 ). Machine tool according to one of claims 19 or 20, characterized by an electrical control for actuating the positioning device ( 10 ) arranged to perform a method according to any one of claims 22 to 23. Method for aligning a workpiece, comprising the step of clamping the workpiece ( 56 ) on a machine tool according to one of claims 20 or 21. A method according to claim 22, characterized by the steps of: (a) detecting a contour of the workpiece ( 56 ) with a measuring device, (b) determining an eccentricity and a wobbling deviation of the workpiece and (c) driving the positioning device ( 10 ) such that the eccentricity and the wobble deviation are reduced. A method according to claim 22 or 23, wherein the workpiece an optical component having an optical axis is characterized through the steps: (a) detecting the optical axis of the component, (B) Determining a deviation of the optical axis from the axis of rotation the machine tool and (c) driving the positioning device so that the deviation is reduced. Method according to one of claims 23 or 24, characterized by the step of machining the workpiece ( 56 ), in particular by Grinding, turning, milling and / or hard turning. Method according to one of claims 23 to 25, characterized through the step: - To capture a position of the positioning device relative to the machine tool, - To capture a machining force on the workpiece and - Drive the eccentric and / or the tilt piezo actuators so that the one Deflection of the workpiece due to the processing power reduce or compensate.