DE10360918A1 - Clamping device with at least one electromechanical actuator as a clamping element - Google Patents

Abstract

A clamping device, in particular a tool holder, comprises at least two clamping surface regions (118, 120) which are provided at a distance from each other at a distance (a) to form a clamping space and from which clamping surface regions (118, 120) for varying the distance dimension (a ) at least one clamping surface region (118, 120) with a displacement component (H) to the other and / or displaceable away from the other, wherein the clamping device (110) comprises an actuator (122, 124), through which one in the direction of Displacement component (H) acting force on the at least one displaceable clamping surface area (118, 120) is exercisable. DOLLAR A According to the invention, the actuator (122, 124) at least one actuator body (122, 124) made of electrostrictive material, which changes a length dimension in at least one spatial direction (h) changing an electric potential acting on it, wherein the electrostrictive actuator body (122 , 124) is provided such that the change in its length dimension causes a change in the application of force to at least the displaceable clamping surface area (118, 120).

Description

The The present invention relates to a clamping device with at least two clamping surface areas, which form a clamping space between them at a distance from each other are provided and of which at least to change the distance measure a clamping surface area with a displacement component on the other clamping surface area to and / or displaced away from the latter, wherein the tensioning device an actuator, through which one in the direction of the displacement component acting force on the at least one movable clamping surface area exercisable is.

jigs The type mentioned are generally as screw or vices, as the above tool holder or chuck known. Of particular interest are tool holders for machine tools for Machining with tools rotating about a rotation axis. In the known clamping devices become objects to be clamped held by frictional engagement between the clamping surface areas. By said displaceability of at least one clamping surface area can objects be removed from the clamping space or introduced into this. Furthermore can the clamping surface areas for generating the frictional Clamping force against the object to be clamped are pressed. The shift and the pressure needed Force is applied by the actuator.

At the actuators of the known tensioning devices come different Operating principles for applying the for a displacement and a clamping force Force to use. Some clamping devices, in particular tool holders have as an actuator, a union nut on, with clamping device and union nut are formed such that by screwing the nut on the Clamping device between existing clamping surface areas clamping space is reduced or the clamping surface areas be pressed against an object to be clamped. In other fixtures in turn, hydraulic pressure chambers are formed, with a change the distance measure between the clamping surface areas by change the pressure of the fluid present in the pressure chambers is effected. Finally are Also known clamping devices in which the clamping surface areas by heating the tensioning device and the resulting thermal expansion the clamping device for enlarging the existing clamping space are shifted away from each other. During the subsequent cooling the clamping surface areas through the with the cooling shifting shrinkage on each other, wherein they Reduce clamping space, so that they force on the object to be clamped come into contact and this frictionally clamped between them hold.

Though is a good clamping effect with these known clamping devices achievable, but requires technical progress and thus associated increasing demands for decreasing production costs and increasing machining accuracy a steady evolution the known clamping devices.

So is with the union nut an additional Component necessary, in which often by further constructive measures the risk of unintentional release of the nut by the clamped Object occurring vibrations or chatter occurring eliminated becomes. The above mentioned Pressure chambers, in turn, are awkward too finished and against leakage of pressurized fluid at the required high To press seal. Finally is the thermal restraint in the work preparation relatively geräte- and time-consuming, since the clamping device on the one hand heated and on the other hand accelerated by heat sink be cooled got to.

It is therefore an object of the present invention, a clamping device specify which with a simple structure a clamping and unclamping objects in a short time and with great Security possible.

These The object is achieved by a Clamping device of the type mentioned above, in which the actuator at least one actuator body made of electrostrictive material, which under change an electrical potential acting on it its length dimension in at least one spatial direction changes, wherein the electrostrictive actuators body is provided on the tensioning device that the change of his length dimension a change the exercise of power effected on at least the displaceable clamping surface area.

For the purposes of this application, "electrostrictive" means any material which changes a length dimension in at least one spatial direction when a change in an electric potential is applied to the material an electrical voltage applied thereto, length dimensions in two or in all Raumrichtun changes. As such materials, for example, piezoelectric materials and so-called carbon nanotubes (CNT) are known. The carbon nanotubes in particular are of interest for the present application since carbon nanotubes already undergo a change in length at very low voltages in the single-digit volts range, which exceeds that of piezoelectric materials by a multiple. In addition, carbon nanotubes have very high mechanical strength and thermal resistance. However, it is also conceivable to use other electrostrictive materials.

The change of acting on the actuator body electric potential is changed by changing an acting on the actuator body electrical Potential from a first potential value to a second potential value reached. In this case, one of the two potential values can be advantageous be a potential, which is the at least one actuator body without Applying to an external voltage has as potential source.

in the Case of an actuator with an actuator body of electrostrictive Material may be the available Clamping space between the clamping surface areas or more precisely the distance between clamping surface areas as well as the pressing force, with which the clamping surface areas be pressed against an object to be clamped by applying electrical voltage to the actuator body to be changed. The change in length of the actuator body and the change associated with it the distance measure between the chip areas or the pressing force takes place in extremely short time Time, allowing a clamping and unclamping of objects in The clamping device can be completed quickly. Thinking on to a use of the clamping device as a tool holder for tools for machining, so usually occur in their use no electrical voltages which are applied by the tensioning device clamping forces can influence.

When Clamping surface region in this application is a surface area denotes, which for abutment against a subject to be clamped is designed and provided. It can be inventively provided be that the spaced clamping surface areas in theirs from the outside uninfluenced basic position have only a very small distance measure and these clamping surface areas by applying an electrical voltage to the at least one displaceable electrostrictive actuator body with one another away displaced shifting component, i. the clamping space is enlarged. Furthermore The clamping device can also be designed for reverse operation be, i. the clamping surface areas wise in their externally uninfluenced Ground state a very large distance on, with the clamping surface areas then by applying an electrical potential to the at least an electrostrictive actuator body for reducing the clamping space and for clamping an object be moved towards each other. Finally, can the tensioning device be designed such that the clamping surface areas by applying different electrical potentials to the at least an electrostrictive actuator body both towards and away from each other can. The for the Shifting applies to the direction of a force exerted on the at least one clamping surface area actuating force corresponding.

From is the above-described embodiments of the clamping device those preferred in which by the movement of the at least one displaceable Clamping surface area the tensioning device between a clamping state and a release state is adjustable, wherein the clamping state of the clamping device an undeformed ground state of the actuator body is assigned, and wherein the release state of the clamping device is a deformation state of the actuator body with one opposite changed the ground state in at least one spatial direction Longitudinal dimension assigned is.

When undeformed ground state is the state of at least one actuators body drawn, in which no external electrical potential on the electrostictive actuator body acts. This is about a state in which no electrical Potential of a separate potential source applied to the actuator body is. The advantage of the embodiment just mentioned is that the tensioning device is in the clamping state without external influence, so that an object clamped in it is safe even in the event of a power failure is held by the tensioning device. In addition, then the clamping forces do not have from the actuator body be permanently applied, but it is sufficient that this the clamping forces only for a short time to remove or change the einzuspannenden Item overcomes.

Preferably, the clamping device of the present invention is a tool holder which is provided on machine tools for machining with rotating geometrically determined or indefinite cutting. This means that the clamping device and tool rotate together, so that the clamping device is rotationally symmetrical with respect to a rotational symmetry axis for the best possible concentricity, wherein the rotational symmetry axis extends between the clamping surface regions and ideally together with the axis of rotation of the tool holder rotation menfällt. If in this application of a radial and axial coordinate direction and a circumferential direction is mentioned, these directions are always related to the rotational axis of symmetry.

According to one first alternative to a development of the clamping device according to the invention the clamping surface areas at clamping surface carrier sections provided a clamping surface carrier, which in turn is connected or connectable to a device main body is. Of at least two existing clamping surface support sections is at least one with a displacement component on the other clamping surface carrier section trained to and / or displaced from this. Besides that is the at least one electrostrictive actuator body provided such that by him at least one force acting in the direction of the displacement component on the displaceable clamping surface carrier section exercisable is. This can ensure that the distance between the at least two clamping surface areas variable is, so that an object held clamped between the clamping surface areas can be. In the development of the invention discussed here is the at least one actuator body in other words with the at least one displaceable clamping surface carrier section in power transmission connection, that the dimensional change of the actuator body in a distance measure between the clamping surface areas changing shift of the at least one displaceable clamping surface carrier section, that is to say in one in this direction of displacement on the at least one Spannflächenträgerabschnit translated acting force becomes.

at This development of the present invention, the clamping surface carrier one for tightening objects particularly suitable material, such as steel, be selected. The clamping surface carrier can continue according to the requirements for a secure clamping be formed, such as by roughening the clamping surface areas or by forming the clamping surface areas with one supporting the clamping Contour, etc. It can thus be optimally adapted to the intended clamping task trained clamping surface carrier used become.

Of the Clamping surface can for example, tubular, be designed as a tubular sleeve. Thereby can the clamping surface carrier and can do that connected the clamping surface areas surrounded by an object to be clamped and thus of several Sides exert a clamping force on this.

at The aforementioned tool holders are the geometries to be clamped usually cylindrical or circular cylindrical shafts of rotating tools, such as drills, milling cutters, reamers etc. A circular-cylindrical clamping surface carrier, which surrounds the shanks to be clamped, offers here the largest possible contact surface given space and thus the maximum achievable clamping force. In this case, an entire inner peripheral surface of the circular cylindrical tubular clamping surface carrier with a clamping surface infinitely many freely definable clamping surface areas. At this are accordingly also clamping surface carrier sections freely definable.

It can basically however, it is also intended to use elliptical-cylindrical tubular surface carriers, in which in the clamping state of the clamping device predetermined peripheral portions abut the object to be clamped and other peripheral sections Distance from this are located. Such an elliptical-cylindrical tubular Clamping surface is with less power deformable as a circular cylindrical, since the deformation in the elliptical-cylindrical Clamping surface essentially is based on the bend while the circular cylindrical clamping surface carrier against the modulus of elasticity of his material must be stretched or compressed.

The for the displacement of the at least one clamping surface area required Power can be reduced by the fact that the clamping surface carrier a Comprises a plurality of clamping surface support sections. An advantageous tensioning device, which objects arbitrary Geometry can clamp, resulting in training by that each clamping surface carrier section at least one actuator body assigned. Here, each clamping surface carrier section by its own actuator body regardless of the other respective clamping surface carrier sections be designed to be movable.

It is particularly advantageous if the at least one clamping surface carrier is formed integrally with the device main body, since on the one hand a very small number of components is required and on the other hand a clamping force can be obtained simply from an elastic deformation of the clamping surface carrier relative to the device main body. This is particularly possible if the at least one clamping surface carrier is resiliently formed integrally with the device main body, approximately projecting therefrom. Due to the small number of components and the simple manufacture, it is preferable to provide the elastic spring force by bending clamping surface carrier sections. For this purpose, a tubular slotted Spannflächenenträger be used, which is more precisely distributed in the circumferential direction provided with in the radial direction of the clamping surface carrier passing through and extending in the axial direction slots.

Of the at least one clamping surface carrier can however, even without integrally formed with the device main body to be resiliently provided on this, for example by suitable Connecting means. The elastic spring force with which the clamping surface area with a displacement component on another clamping surface area to or / and away from this, can from the at least a clamping surface carrier itself, about be obtained by the bending, or it may be a spring element be provided, which is supported on the one hand on the clamping surface carrier and on the other hand on the device main body.

Of the common Case of rotationally symmetrical clamping devices, in particular Tool holders of the type mentioned above, is a clamping of a Object between two clamping surface areas, so that the Clamping surface carrier radial outside the object to be clamped is located. In such a case can be used to displace the at least one displaceable clamping surface carrier section and to exercise power on this at least one actuator body with radially larger distance arranged by the rotational symmetry axis of the tensioning device be as the at least one Spannflächenenträger. In this arrangement can the at least one actuator body the clamping surface carrier sections of the clamping surface carrier in radial Direction very easy to the symmetry axis and / or from this move away.

constructive this can be done this way be that a plurality of actuator bodies is provided, which the rotational symmetry axis surrounding on a longitudinally closed, preferably substantially cylindrical, more preferably circular cylindrical area arranged such that a change of the acting on them electric potential a change the length dimension effected in the radial direction and / or in the circumferential direction. The actuator body can become doing so in the direction of the axis of rotational symmetry over a predetermined length in the Stretching device to sufficiently large displaceable clamping surface areas to be able to provide.

According to one Development of the invention can the actuator body be arranged so that when changing the electrical force acting on them Potentials their length dimension changes in the radial direction. additionally or alternatively the actuator body be arranged such that a change of the acting on them electric potential a change their length dimension effected in the circumferential direction. This allows the scope of a circular cylindrical area can be extended, on which the actuator body can be arranged so that it is a desired one Relocation of clamping surface areas and a desired one pressing force comes.

According to one further constructive configuration, the plurality of actuator bodies radially Outside in the circumferential direction at least in sections of at least one Zugwand be surrounded, which with the clamping surface support sections through in radial Direction between the actuator bodies running webs is connected. In such a training are the actuator body in the radial direction between clamping surface carrier and pulling wall, wherein the draft wall due to expansion or shrinkage of actuator bodies a change of the on the actuator body acting electrical potential shifted more than the radial internal clamping surface carrier sections. The movement of the pulling wall is transmitted through the webs to the clamping surface carrier sections, so they were taken off the train wall during their relocation become.

alternative to a plurality of actuator bodies The electrostrictive actuator body can also sleeve-like the clamping surface carrier sections be formed surrounding. For example, the actuator body in easy way around the clamping surface carrier around be wrapped. It can also for targeted control of the clamping surface carrier sections a plurality provided in the axial direction separate and individually controllable actuator bodies be.

According to one alternative development of the present invention, the at least a movable clamping surface area also be formed on the at least one actuator body itself. For targeted adjustment of clamping surface areas as well as for application one possible huge Tension can several actuator bodies provided or a plurality of clamping surface areas on the at least an actuator body be educated.

in the Contrary to the above embodiment, in which the actuator body designed to move a clamping surface carrier is, the actuator body the embodiment now discussed itself Clamping surface regions on. This allows the number of components of the clamping device be further reduced, however, the designer is in the election the material on which the clamping surface area are formed should, no longer free.

In principle, it can be thought of, the at least one actuator body on one side spans on a body of the tensioning device projecting from this. However, in order to transfer the greatest possible clamping force, it is advantageous if the actuator body is of sleeve-like design and the clamping device has a surrounding section which surrounds the sleeve-like actuator body at least in sections in a circumferential direction about the rotational symmetry axis. The enclosure section serves to support the sleeve-like actuator body. Due to the support of the actuator body on Umfassungsabschnitt the expansion of the actuator body is bounded radially outward, so that a change in length or volume of the actuator body in the radial direction or in the circumferential direction mainly leads to a displacement of the inner peripheral surface of the sleeve-like actuator body in the direction radially inward. The space surrounded by the sleeve-like actuator body is the clamping space.

In order to the sleeve-like actuators body both securely supported on Umfassungsabschnitt, as well as range of motion has at least in peripheral portions, the clamping device be formed such that an outer surface of the sleeve-like actuator body at least has two investment areas, with which the actuator body an inner surface of the enclosure section, and at least two clearance areas having, with respect the rotational symmetry axis radial distance to the inner surface of the Surrounding portion are arranged, wherein in the circumferential direction of the Actuator outer surface between two contact areas each a distance range is arranged.

To the secure clamping of an object, preferably a shaft, has an inner surface of the sleeve-like actuators body at least two clamping surface areas on. These clamping surface areas are preferably in the radial direction of the inner surface of the sleeve-like actuators body in front. Then that is is their investment area defines what makes it possible the contact pressure of the clamping surface area to determine the object to be clamped as accurately as possible.

The Clamping and unclamping objects into or out of the tensioning device can thereby be relieved that the clamping surface areas one possible huge Move towards and / or away from each other. This is constructive For example, realized by the fact that the clamping surface areas in the distance ranges associated peripheral portions of the sleeve-like actuators body are provided.

to Maintenance, replacement or use of tensioning devices, which for clamping tool shanks of different diameters are formed, the sleeve-like actuators body detachable from the clamping device and thus arranged interchangeable be.

Prefers can the sleeve-like actuators body and a surrounding at least partially surrounding wall be arranged removably together from the clamping device, such as pre-assembled or pre-assembled module. This has the advantage that always one to the respective respective actuator body suitable Umfassungswand may be provided, regardless of the design of the clamping device or the device main body.

Finally, can the preassembled module next to the actuator body instead of or in addition to a this radially outside enclosing surrounding wall also include a previously mentioned clamping surface support, which of the sleeve-like actuators body is surrounded. The clamping surface carrier can slotted or broken to those for the displacement of the clamping surface areas to reduce required forces.

According to one third embodiment The present invention may as an actuator with a substantially incompressible fluid filled Pressure chamber to be formed in the clamping device, wherein increase the fluid pressure in the pressure chamber for the displacement or / and for pressing the clamping surface areas required personnel be generated. In a simple way, the fluid pressure can thereby a change a length dimension the electrostrictive actuator body be effected. For this purpose, for example, the actuator body, at least be arranged in sections in the pressure chamber, where he by changing an electrical potential acting on it at least one length dimension in a spatial direction and thus its volume changes, so that at a substantially incompressible fluid by displacing its pressure in the sealed Chamber increased becomes.

Also, an initially addressed solution with a union nut can be realized using the electrostrictive actuator body. For this purpose, the tensioning device may be designed such that the actuator has an adjustable with respect to the device main body in the direction of rotational symmetry clamping element, such as a cap nut, wherein the clamping surface areas by adjusting the clamping element with a movement component towards each other and / or away from each other are displaced, such as Providing a conical contact surface on at least one clamping surface carrier and a voltage applied to this conical counter-contact surface on the clamping element, wherein the at least one Akto renkörper is provided on the clamping element such that a change in its length dimension causes a change in the length dimension of the clamping element such that change the forces transmitted by the clamping element on the clamping surface areas. This embodiment can be adjusted both by changing the electrical potential acting on the actuator body and, in the absence of a potential or voltage source, mechanically between clamping state and release state.

According to one Development of the invention can also be the entire clamping device, about the entire tool carrier, be made of electrostrictive material.

in the previous text has been i.a. a clamping of objects in a rotationally symmetrical clamping device explained, wherein the clamping force radially inward on the rotational axis of symmetry is addressed to. Of course you can the tensioning device also for clamping engagement on inner circumferential surfaces, i. formed with in the radial direction away from the axis of symmetry forces be.

The The present invention will now be described in detail with reference to the accompanying drawings Drawings described. It shows:

1 a longitudinal sectional view of a first embodiment of a tensioning device according to the invention in the form of a tensioning rod,

2a a longitudinal sectional view of a second embodiment of a clamping device according to the invention in the form of a tool holder,

2 B a front view of the tool holder of 2a .

3 a third embodiment of the clamping device according to the invention,

4a a longitudinal sectional view of a fourth embodiment of a clamping device according to the invention,

4b a front view of the same,

5 A fifth embodiment of a tensioning device according to the invention,

6 A sixth embodiment of a chip device according to the invention,

7a a longitudinal sectional view of a seventh embodiment of a erfindungsmäßgen clamping device,

7b a view of a removable assembly for clamping,

8a a longitudinal sectional view of an eighth embodiment of a clamping device according to the invention,

8b a front view of the same,

9 a longitudinal sectional view of a ninth embodiment of the present invention,

10 a longitudinal sectional view of a tenth embodiment of the present invention,

11 to 14 an eleventh to fourteenth embodiment of a clamping device according to the invention,

15 a longitudinal section through a fifteenth embodiment of a clamping device according to the invention, as well as

16 to 20 each a longitudinal section through a sixteenth to twentieth embodiment of a clamping device according to the invention.

In 1 is a clamping device according to the invention as a vise in general with 10 designated. The vice 10 comprises a device main body 12 with therein in the direction of the double arrow H slidably mounted clamping surface carriers 14 and 16 , At the clamping surface carrier 14 is one to the clamping surface carrier 16 indicative clamping surface area 18 educated. Likewise is on the clamping surface carrier 16 one to the clamping surface carrier 14 indicative clamping surface area 20 educated. The clamping surface areas 18 and 20 are in the representation of 1 in the direction H, the distance a distance from each other. The space between the clamping surface areas 18 and 20 is the clamping space 26 ,

Furthermore, the tensioning device 10 actuators body 22 and 24 on. These actuators are at a longitudinal end with the device main body 12 and at its opposite longitudinal end with its respective associated clamping surface carrier 14 respectively. 16 for example, connected by gluing. Incidentally, in all the illustrated embodiments, the at least one actuator body has tensile and / or compressive force transmitted to the tool holder, such as by gluing.

The actuator body 22 and 24 are made of electrostrictive material, ie of a material al, which changes its length dimension in at least one spatial direction by changing an electric potential acting on the material. Optionally, the material may be chosen to expand or contract to alter the electrical potential. Preferably, so-called "carbon nanotubes" are used as electrostrictive material.

In the present case the embodiment of 1 are the actor bodies 22 and 24 connected to potential sources, not shown, such as electrical DC voltage sources, whose electrical potential is variable. By changing the on the actuator body 22 and 24 acting electrical potential, at least the length dimension of this actuator body changes in the direction of the double arrow H, as indicated by the arrows h. Accordingly, the distance measure a by changing the to the actuator body 22 and 24 applied electrical potentials or electrical voltages are increased or decreased so that between the clamping surface areas 18 and 20 an object can be clamped.

In 2a is a longitudinal section through a tool holder 110 as a second embodiment of a tensioning device according to the invention. The tool holder known in its basic form 110 has a device main body 112 on which at his in 2a Right longitudinal end of a substantially circular cylindrical clamping space 126 is provided. The tool holder 110 is substantially rotationally symmetrical with respect to a rotational symmetry axis R, the rotational symmetry axis R also being the axis of rotation D of the tool holder 110 and the center axis of the circular cylindrical clamping space 126 is.

Integral with the device main body 112 formed is a clamping surface carrier 114 , The clamping surface carrier 114 is formed like a tube, wherein its inner peripheral surface has a plurality of opposing clamping surface areas 118 and 120 having. These clamping surface areas 118 and 120 are at respective clamping surface support sections 119 and 121 educated.

Radially outside of the clamping surface carrier 114 along a circular cylinder surface, a plurality of rod-like electrostrictive actuator bodies are arranged, of which exemplified in 2a the actuator body 122 and 124 lie in the cutting plane. The tension surface carrier sections 119 and 121 are assigned to the actuator bodies in the circumferential direction. The actuator body 1122 . 124 , etc. are on a circular cylindrical surface concentric with the rotational symmetry axis 125 arranged in which 2 B is indicated as a dot-dashed segment line.

Again radially outward are the actuator body 122 and 124 from a train wall 128 surrounded, which train wall 128 , as in 2 B can be seen by extending in the radial direction between the actuator bodies webs 130 with the clamping surface carrier 114 and in particular with the clamping surface support sections 119 . 121 , etc. is connected.

The tool holder 110 with its clamping surface carrier integrally provided thereon 114 is formed such that in a ground state of the actuator body, that is, in a state in which no externally applied electric potential acts on the actuator body, the distance measure a between opposing clamping surface areas 118 and 120 is minimal. If now a predetermined electrical potential is applied to the actuator body, then it expands at least also in the radial direction, possibly in all spatial directions, while being radially outward against the pulling wall 128 and radially inward against the clamping surface carrier 114 to press. Since the radially outwardly pointing portion of the surface surrounding the individual actuator bodies is larger than the radially inward-pointing portion, the radially outward direction is on the pulling wall 128 acting force greater than the force acting radially inwardly toward the axis of rotational symmetry R towards force, so that the pulling wall 128 at an extension of the actuator body by means of the webs 130 due to the greater force acting on them the clamping surface areas, such as 118 and 120 , displaced radially outward, so that the distance a increases.

An advantage of this arrangement is that a clamping force of elastic deformation of the sleeve-shaped clamping surface carrier 114 results and the actuator body itself must apply no clamping force. Rather, it is sufficient if these briefly apply a force for widening the distance measure a. In addition, the application of an electrical voltage to the actuator body can be carried out in tool holder removed from a machine tool.

In 3 a further embodiment of a clamping device according to the invention in the form of a tool holder is shown. In connection with 3 as well as with the following 4 to 20 , are the same components with the same reference numerals as in 2 provided with the same reference numerals, but each increased by a multiple of 100 , The 3 to 20 are explained only insofar as they differ from 2 differ. In 3 are the same components as in 2 provided with the same reference numerals, but increased by the number 100 ,

In 3 is the clamping surface carrier 214 from a sleeve or tubular actuator body 222 surrounded, which is arranged concentrically to the axis of rotational symmetry R. The actuator body may be made of the above-mentioned carbon nanotubes, for example, by winding or laminating a plurality of layers, as well as any other shaping method used to produce a sleeve-shaped actuator body 222 is suitable, can be used for its preparation. The sleeve-like actuator body 222 may be oriented such that it expands or contracts upon application of an electrical voltage thereto in the radial direction and / or in the circumferential direction. Due to the sleeve-like design of the actuator body always performs an expansion in the radial direction and a change in length in the circumferential direction and vice versa. The whole of the essentially circular cylindrical clamping space 226 delimiting inner peripheral surface of the clamping surface carrier forms a clamping surface. This can be done by con traction of the actuator body 222 be reduced, so that a distance measure a between two opposing clamping surface areas 218 and 220 reduced. However, the distance dimension in a basic state of the actuator body is preferred 222 minimal. It is then always enlarged by extension of the actuator body.

In 4a and 4b are the same components as in 2 provided with the same reference numerals, but increased by the number 200 ,

Again, the actuator body 322 radially outside of the clamping surface carrier 314 this surrounding coaxial with the rotational symmetry axis R arranged.

4b is a cross-sectional view along the plane IVb-IVb in 4a , The clamping surface carrier 314 has in the axial direction extending and in the radial direction of the clamping surface carrier 314 penetrating slots 332 on. This is the clamping surface carrier 314 segmented formed in the circumferential direction. Exemplary are in 4b the clamping surface carrier sections 319 and 321 denotes, on which the clamping surface areas 318 respectively. 320 are provided to the rotational axis of symmetry R hinweisend. The on an object in the clamping space 326 , For example, a cylindrical shaft of a cutting tool, exerted clamping force results from the material elasticity of the individual clamping surface sections 319 . 321 when bent about a rotational axis of symmetry R orthogonal bending axis. The bending axis is in this case with respect to each clamping surface support portion such that the clamping surface area provided on it is bent away from the rotational axis of symmetry radially outward. The bending force for clamping and unclamping objects is, as described above, briefly through the actuator body 322 effected by changing the voltage acting on it or the electrical potential.

In 4a Another arrangement is shown which improves the machining accuracy of a tool holder 310 clamped tool is used. Distributed over the circumference are other actuator bodies 340 arranged in the circumferential direction at equal intervals from each other. Every other actuator body 340 are a potential source 342 , an electrical connection cable 344 and a switch 346 assigned. The desk 346 , Preferably, an electrical switch, such as a thyristor, is also provided with a receiving part, which switching commands from an external radio transmitting device 348 receives.

By coding from the radio transmitter unit 348 radiated commands is every switch 346 individually controllable. By targeted activation of certain other actuator body 340 For example, the device main body 312 be deformed such that any concentricity deviations are reduced compared to an undeformed state. The control of the other actuator body 340 through the radio transmission unit 348 takes place in that the switch 346 receives from this one addressed to him command signal with the instruction, the associated power line 344 to make conductive. If this is conductive, then the electrical potential of the assigned potential source acts 342 on the other actuator body 340 a, whereupon this changes a length dimension in at least one spatial direction. This allows the Tool Center Point (TCP) one in the tool holder 310 clamped cutting tool in the order of hundredths of a millimeter in the radial direction with respect to the rotational symmetry axis R are shifted.

Stepping on the tool holder 310 Vibrations, it may also be thought, a part of the other actuator body 340 periodically to change its length dimension, namely by periodically driving the associated switch 346 , This makes it possible to generate a counter vibration or at least an oscillating mechanical stress which reduces or even eliminates the externally excited unwanted vibration by destructive interference.

In 5 are the same components as in 2 provided with the same reference numerals, but increased by the number 300 ,

In the 5 shown embodiment of a tool holder 410 corresponds substantially to the embodiment of the 2a and 2 B , with the difference that instead of a variety of a circular-cylindrical sleeve-like actuator body along a rod-like actuator bodies arranged coaxially to the rotational symmetry axis R 422 is used.

The actuator body 422 is on a perimeter wall 428 supported, which surrounds him radially outwardly coaxial. Advantageously, the material of the actuator body 422 chosen such that it contracts under the application of a predetermined electrical voltage, so that thereby facing each other, diametrically opposite clamping surface areas 418 and 420 be displaced away from each other in the radial direction and thus the distance a increases. This in turn ensures that the actuator body 422 only for clamping and unclamping tools from the tool holder 410 must be supplied with a voltage.

In 6 are the same components as in 2 provided with the same reference numerals, but increased by the number 400 ,

The embodiment of 6 is essentially the same as 5 , only the clamping surface carrier 514 is not integral with the device main body 512 connected. In addition, a plurality of similar annular actuator body coaxially spaced apart in the direction of the rotational symmetry axis R from each other. Of these actuators are exemplified the actuator body 522 and 524 provided with reference numerals. The actuator body can individually acted upon by a voltage, so that different clamping forces can be generated at axially different positions. To support the application of different clamping forces in the axial direction is by the formation of circumferential annular grooves 550 at the clamping space 526 delimiting inner surface of the clamping surface carrier 514 favored. Through these circumferential grooves 550 Also, a plurality of axially spaced apart clamping surface support portions are provided.

In the 7a and 7b are the same components as in 2 provided with the same reference numerals, but increased by the number 500 , Furthermore, the same components as in 4a provided with the same reference numerals, but increased by the number 200 ,

In a pipe section of the device main body 612 is a preassembled module 660 recorded in which 7b is shown in isolation. The assembly 660 includes a perimeter wall 628 , A plurality of annular actuator bodies, for example, the actuator body 622 and 624 , as well as the clamping surface carrier surrounded by the actuator bodies 614 , To describe the shape of the actuator body and the clamping surface carrier is expressly to the description of these components in 6 directed.

The coaxially arranged similar annular and axially spaced actuator body can from the outside by connecting the voltage source 662 be prompted to a dimensional change. Preferably, the material of the actuator body is selected such that under application of a certain voltage to the distance a increases between two diametrically opposite clamping surface areas.

In 7a is also a switching element 646 ' represented, which at the same time a sensory property with respect to the tool holder 610 occurring vibrations, ie mechanical stresses and / or deformations has. Detects the switching and sensor element 646 ° such a vibration, it connects the other actuator body 640 with the voltage source 642 such that, in the manner described above, a counter-vibration is generated to reduce the unwanted vibration by destructive interference.

In 8a and 8b are the same components as in 2 provided with the same reference numerals, but increased by the number 600 ,

In 8a is a sleeve-shaped actuator body 722 from a perimeter wall 728 which is integral with the device main body 712 is trained. On the inner surface of the sleeve-like actuator body 722 are in the radial direction to the axis of rotational symmetry R back protruding clamping surface areas 718 and 720 and another unnamed clamping surface area is formed. At his to the perimeter wall 728 indicative outside is the actuator body at investment areas 722a . 722b and 722c in abutting contact with an inner surface of the perimeter wall 728 , In the circumferential direction lying between each two adjacent abutment sections are spacing areas 722d . 722E and 722f provided in which a radial and axial gap between the inner surface of the enclosure wall 728 and the outer surface of the actuator body 722 is available. The distance ranges are constructive 722d to 722f formed by the wall thickness of the sleeve-like actuator body 722 is made thinner in these areas than in the investment areas 720a to 720c ,

The clamping surface areas 718 . 720 are preferred in the distance ranges of the actuator body 722 formed, as this ensures the greatest possible movement of the clamping surface areas in the radial direction. Preferably, the Ak gates body 722 formed such that it expands under application of a predetermined electrical voltage, so that the clamping surface areas, as indicated by arrows in 8b indicated, be shifted to the outside. Then the actuator body exercises 722 in its ground state, ie without applying an electrical potential from the outside, a clamping force on a sufficiently large object, such as a cutting tool shank, in the clamping space 726 out. This clamping force is retained even in the event of a power failure.

In 9 are the same components as in the 2 provided with the same reference numerals, but increased by the number 700 ,

On the actuator body 822 are formed a plurality of axially spaced-apart clamping surface areas. Between adjacent clamping surface areas in the axial direction are circumferential annular grooves 850 intended. Essentially, the design of the actuator body corresponds 822 the formation of the clamping surface carrier 614 in 7b , whose description is hereby expressly referenced. In the embodiment according to 9 serves the actuator body 822 as a clamping surface carrier.

In 10 are the same components as in 2 provided with the same reference numerals, but increased by the number 800 ,

The integral with the device main body 912 trained clamping surface carrier 914 , which is circumferentially segmented into a plurality of clamping surface support portions, is on its radially outwardly facing surface 914a conical.

The tensioning device 910 has a union nut 964 on which in one with the outer surface 914a of the clamping surface carrier 914 co-operating axial length portion with a conical inner peripheral surface 964a is trained. By screwing on the union nut 964 on the thread 966 at the device main body 912 Thus, a force is exerted on the clamping surface areas of the clamping surface carrier in the radial direction. The clamping surface areas are moved toward each other and this is a clamping one in the clamping space 926 reached object reached.

The union nut 964 has a plurality of circumferentially equidistant actuator bodies 922 and 924 on, which by means of an external electric potential source 964 can be acted upon by a predetermined electrical voltage. Advantageously, the actuator material is chosen such that it expands upon application of a predetermined electrical voltage, so that thereby the clamping force on the clamping surface areas 918 . 920 reduced and one in the clamping space 926 clamped tool can be removed.

alternative can the union nut also instead of having a plurality of electrostrictive actuator bodies with a ring revolving actuator body be provided of electrostrictive material. The advantage of this Arrangement is that in case of power failure, the clamping of a tool can be mechanically generated and canceled, with existing electricity but very fast and reliable by applying or not applying the mentioned electrical potential or by applying appropriately selected different electrical potentials.

In the 11 to 14 Embodiments of another clamping device according to the invention are shown, wherein the same components in the 11 . 12 . 13 and 14 as in 10 are provided with the same reference numerals, but increased by the number 100 ,

The embodiments of the 11 to 14 differ from the embodiment of the 10 only by the type of application of the clamping force. In the 11 to 14 is one of the union nut 964 in 10 similar element 1064 not at the device main body 1012 screwed, but biased by compression springs so that it causes an elastic bending of the respective clamping surface support portions in the radial direction, through which a clamping state of the clamping device 1010 is reached. The tensioning element 1064 is each by a tension spring 1066 biased in the manner previously described.

In the 11 and 12 is the outer surface 1014a the clamping surface carrier tapering towards its free longitudinal end, so that the clamping element 1064 in a direction indicated by the arrow S direction by the compression springs 1066 is biased. The compression springs 1066 rely on the device main body at one end 1012 and at the other end to an annular surface of the clamping element 1064 from. In 11 is an actuator body 1022 provided, which contracts upon application of a predetermined voltage, and thereby against the restoring force of the compression springs 1066 the clamping element 1064 adjusted counter to the direction S, so that the distance a increases between diametrically opposite clamping surface areas due to elastic forces of Spannflächenträgerabschnitte.

In contrast, in 12 used electrostrictive actuator body, which is at Apply applying a predetermined voltage expand. In 11 can be provided alternately in the circumferential direction in each case a pressure surface and an actuator body.

The embodiment of 13 corresponds substantially to the embodiment of 12 with a to the free longitudinal end of the clamping surface carrier 1014 towards widening conical outer surface 1014a , Likewise, the embodiment of 14 essentially the in 11 shown embodiment, taking into account the reverse taper of the outer surface 1014a of the clamping surface carrier 1014 ,

In 15 is a tool holder 1110 shown, which is made entirely of electrostrictive material.

The embodiments of the 16 to 19 correspond substantially to the embodiment of 2 whose description is expressly referred to. The 16 to 19 show plan views of the respective clamping device of the insertion direction of a tool to be clamped parallel to the rotational axis of symmetry R viewed from.

In 16 are the same components as in 2 provided with the same reference numerals, but increased by the number 1100 , The embodiment of 16 is different from the one in 2 B essentially in that the rod-shaped actuator body 1222 have a more developed extent in the radial direction and are not formed circular cylindrical. This allows a greater absolute change in length in the radial direction can be achieved.

In 17 are the same components as in 2 provided with the same reference numerals, but increased by the number 1200 , actuators body 1322 . 1324 are formed with a circular sector-shaped cross-section. In the circumferential direction three actuator body are provided, each by a radially extending web 1330 are separated from each other. The clamping surface carrier 1314 is made divided by slits extending in the axial direction, so that three separate, non-contiguous clamping surface support sections are provided. By way of example, the clamping surface carrier sections 1319 and 1321 designated. Again, the principle applies here that by expansion of the actuator body, the tensile wall 1328 by means of the webs 1330 which entrains the webs respectively associated clamping surface carrier portions radially outward.

The embodiment of 18 corresponds essentially to a combination of the embodiments of 16 and 17 , Along an axis of rotation of the axis of symmetry R coaxial circular cylinder arranged electrostrictive actuator body 1422 . 1424 , etc. are by radially extending webs 1430 separated from each other, wherein the webs 1430 slotted are executed.

The embodiment of 19 corresponds substantially to the embodiment of 17 , but where the clamping surface carrier 1514 not slotted executed. The actuator body 1522 . 1524 are formed very voluminous, so that the clamping surface carrier between two adjacent clamping surface support sections, such as between the sections 1519 and 1521 is very thin. As a result, the clamping surface carrier sections 1519 and 1521 be removed with relatively little force from each other, since the effective cross-section of the wall to be stretched is very small.

20 shows a cross section through a further embodiment of a clamping device according to the invention, in which pressure chambers 1670 are formed in the tensioning device, which are filled with an incompressible hydraulic oil. Otherwise, the geometry of the clamping device corresponds to the in 19 . shown In the pressure chambers 1670 are actuator bodies 1622 . 1624 , etc., which expand by applying a predetermined voltage from its base state, so that for the hydraulic oil in the pressure chambers 1670 available volume is reduced. This will cause the pressure in the hydraulic oil chambers 1670 increased, causing the draft wall 1628 is stretched radially outward. This takes over the bridges 1630 the clamping surface carrier sections 1619 . 1621 , etc. radially outward, thereby increasing the clamping space 1626 so that a tool can be removed from or inserted into it.

Claims (26)

Clamping device, in particular tool holder, with at least two clamping surface areas ( 18 . 20 ; 118 . 120 ; ...), which are used to form a clamping space ( 26 ; 126 ; ...) are provided between them at a distance (a) from each other and of which at least one clamping surface area (16) for changing the distance measure (a) 18 . 20 ; 118 . 120 ; ...) with a displacement component (H) on the respective other clamping surface area ( 18 . 20 ; 118 . 120 ; ...) to and / or displaced away from it, wherein the tensioning device ( 10 ; 110 ; ...) an actuator ( 22 . 24 ; 122 . 124 ; ), by which a force acting in the direction of the displacement component (H) on the at least one displaceable clamping surface area ( 18 . 20 ; 118 . 120 ; ...) is exercisable, characterized in that the actuator ( 22 . 24 ; 122 . 124 ; ...) at least one actuator body ( 22 . 24 ; 122 . 124 ; ...) of electrostrictive material, which changes its length dimension in at least one spatial direction (h) while changing an electrical potential acting on it, wherein the electrostrictive actuator body ( 22 . 24 ; 122 . 124 ; ...) on the tensioning device ( 110 ; 110 ; ...) is provided that the change in its length dimension, a change in the application of force to at least the displaceable clamping surface area ( 18 . 20 ; 118 . 120 ; ...) causes. Clamping device according to claim 1, characterized in that by the movement of the at least one displaceable clamping surface area ( 18 . 20 ; 118 . 120 ; ...) the tensioning device ( 10 ; 110 ; ...) between a clamping state and a release state is adjustable, wherein the clamping state of the clamping device ( 10 ; 110 ; ...) an undeformed ground state of the actuator body ( 22 . 24 ; 122 . 124 ; ...), and wherein the release state of the tensioning device is associated with a deformation state of the actuator body with a length dimension that is changed relative to the ground state in at least one spatial direction (h). Clamping device according to claim 1 or 2, characterized in that it is substantially rotationally symmetrical with respect to a rotational axis of symmetry ^® , wherein the rotational symmetry axis between the clamping surface areas ( 18 . 20 ; 118 . 120 ; ...) runs. Clamping device according to one of the preceding claims, characterized in that it comprises a device main body ( 12 ; 112 ; ...) and at least one clamping surface carrier, which clamping surface carrier ( 14 . 16 ; 114 . 116 ; ...) at least two clamping surface carrier sections ( 119 ; 121 ; ...), each with at least one clamping surface area ( 118 . 120 ; ...) from which clamping surface carrier sections ( 119 . 121 ; ...) at least one with a displacement component to the other to and / or away from this, wherein the at least one actuator body ( 22 . 24 ; 122 . 124 ; ...) in such a way with the at least one displaceable clamping surface carrier section ( 119 . 121 ) in motion transmission connection is that the dimensional change of the actuator body ( 22 . 24 ; 122 . 124 ; ...) in a distance measure (a) between the clamping surface areas ( 118 . 120 ; ...) changing the displacement of the at least one displaceable clamping surface carrier section ( 119 . 121 ; ...) is translated. Clamping device according to claims 3 and 4, characterized in that the clamping surface carrier ( 114 ; 214 ; ...; 714 ; ...) is tubular, preferably cylindrical, particularly preferably circular cylindrical, wherein the clamping surface carrier sections ( 119 ; 121 ; ...; 722d -f; ...) peripheral portions of the tubular clamping surface carrier ( 114 ; 214 ; ...; 714 ; ...) are. Clamping device according to claims 3 and 4, characterized in that the clamping surface carrier ( 114 ) a plurality of clamping surface support sections ( 119 . 121 ), from which at least one actuator body ( 122 . 124 ) assigned. Clamping device according to claim 4, optionally incorporating claims 5 or 6, characterized in that the at least one clamping surface carrier ( 114 ; 214 ; ...) integral with the device main body ( 112 ; 212 ; ...) is trained. Clamping device according to one of claims 4 to 7, characterized in that the at least one clamping surface carrier ( 114 ; 214 ; 314 ; ...) so resiliently on the device main body ( 112 ; 212 ; 312 ; ...) is provided that the at least one displaceable clamping surface area ( 119 . 121 ; 219 . 221 ; 319 . 321 ; ...) against an elastic spring force with a displacement component on another clamping surface area ( 119 . 121 . 219 . 221 ; 319 . 321 ) to and / or displaced away from it. Clamping device according to claim 3 and one of claims 4 to 8, characterized in that the at least one actuator body ( 122 . 124 ; 222 . 322 ; ...) with radially greater distance from the rotational symmetry axis (R) than the at least one clamping surface carrier ( 114 ; 214 ; ...) is arranged. Clamping device according to claim 9, characterized in that a plurality of actuator bodies ( 122 . 124 ; ...) is provided, which are the rotational symmetry axis (R) surrounding arranged on a along a circumferential direction about the rotational symmetry axis (R) around, preferably substantially cylindrical, more preferably circular cylindrical surface arranged such that a change in the electrical potential acting on them causes a change in the length dimension in the radial direction and / or in the circumferential direction. Clamping device according to claim 10, characterized in that the plurality of actuator bodies ( 122 . 124 ; ...) radially outside in the circumferential direction at least in sections of at least one pulling wall ( 128 ; ...) is surrounded, which with the clamping surface carrier sections ( 119 . 121 ; ...) by in the radial direction between the actuator bodies ( 122 . 124 ; ...) running bridges ( 130 ; ...) are connected. Clamping device according to one of claims 9 to 11, characterized in that the at least one actuator body ( 222 ; 322 ; ...) sleeve-like the clamping surface carrier sections ( 219 . 221 ; 319 . 321 ; ...) is formed surrounding. Clamping device according to one of claims 1 to 3, characterized in that at least the displaceable clamping surface area ( 718 . 720 ; ...), preferably a plurality of clamping surface areas ( 718 . 720 ; ...), on which at least one actuator body ( 722 ; ...) are formed. Clamping device according to claims 12 or 3 and 13, characterized in that it comprises a surrounding portion ( 728 ; 828 ; ...), wherein the actuator body ( 722 ; 822 ; ...) formed like a sleeve and the enclosing section ( 728 ; 828 ; ...) the sleeve-like actuator body ( 722 ; 822 ; ...) in a circumferential direction around the rotational symmetry axis (R) at least partially surrounds. Clamping device according to claim 14, characterized in that an outer surface of the sleeve-like actuator body ( 722 ; ...) at least two investment areas ( 722a C) with which the actuator body ( 722 ; ...) on an inner surface of the enclosing section ( 728 ; ...) and at least two distance ranges ( 722d -F), which with respect to the rotational symmetry axis (R) radial distance to the inner surface of the Umfassungsabschnitts ( 728 ; ...) are arranged, wherein in the circumferential direction of the actuator body outer surface between two contact areas (7 22a -C) one interval each ( 722d -F) is arranged. Clamping device according to claim 14 or 15, characterized in that an inner surface of the sleeve-like actuator body ( 722 ; ...) at least two clamping surface areas ( 718 . 720 ; ...) having. Clamping device according to claim 16, characterized in that the clamping surface areas ( 718 . 720 ) in the radial direction from the inner surface of the sleeve-like actuator body ( 722 ) protrude. Clamping device according to claim 15 and 16, optionally incorporating claim 17, characterized in that the clamping surface areas ( 718 . 720 ) in the spacing regions ( 722d F) associated peripheral portions of the sleeve-like actuator body ( 722 ) are provided. Clamping device according to claim 12 or one of claims 14 to 18, characterized in that the sleeve-like actuator body ( 622 . 624 ; ...) is detachably arranged by the clamping device. Clamping device according to one of claims 14 to 18 or according to claim 19, when appended to claim 14, characterized in that a preassembled or preassembled assembly ( 660 ) of sleeve-like actuator body ( 622 . 624 ) and a surrounding at least partially surrounding wall ( 628 ) of the tensioning device ( 610 ) is arranged detachably. Clamping device according to one of claims 14 to 18 or according to claim 19 or 20, when appended to claim 14, characterized in that a preassembled or preassembled subassembly ( 660 ) from clamping surface carrier ( 614 ), this surrounding sleeve-like actuator body ( 622 . 624 ) and a peripheral wall surrounding this ( 628 ) of the tensioning device ( 610 ) is arranged detachably. Clamping device according to one of the preceding claims, characterized in that the actuator ( 1670 ) a pressure chamber filled with incompressible fluid ( 1670 ), wherein the actuator body ( 1622 . 1624 ) is provided such that a change in its length dimension, a change in the fluid pressure in the pressure chamber ( 1670 ) causes. Clamping device according to Claims 3 and 4, optionally incorporating at least one of Claims 5 to 22, characterized in that the actuator has a relative to the device main body ( 912 ; 1012 ) in the direction of the rotational symmetry axis (R) adjustable clamping element ( 964 ; 1064 ), such as a union nut ( 964 ), wherein the clamping surface areas ( 918 . 920 ) by adjustment of the clamping element ( 964 ; 1064 ) with a component of movement toward one another and / or away from one another, for example by providing a conical contact surface ( 914a ; 1014a ) on at least one clamping surface carrier ( 914 ; 1014 ) and a voltage applied to this conical counter-contact surface ( 964a ; 1064a ) on the clamping element ( 964 ; 1064 ), wherein the at least one actuator body ( 922 . 924 ; 1022 ) on the clamping element ( 964 ; 1064 ) is provided such that a change in its length dimension, a change of the of the clamping element ( 964 ; 1064 ) causes the force exerted in the direction of the rotational symmetry axis (R). Clamping device according to claim 23, characterized in that the actuator ( 1064 ) an interacting with the at least two clamping surface areas to their displacement actuator ( 1064 ), which between a clamping position, in which the distance measure (a) between the clamping surface areas is smaller, and a release position, in which the distance measure (a) between the clamping surface areas is greater, is adjustable, and which by a restoring force (at 1066 ), in particular spring force, in one of the positions: clamping position and release position, preferably in the clamping position, is biased, wherein the at least one electrostrictive actuator body ( 1022 ) is arranged such that a change in its length dimension in at least one spatial direction an adjustment of the actuating element ( 1064 ) against the restoring force (at 1066) in the other position, preferably in the release position causes. Clamping device according to one of claims 1 to 3, characterized in that it ( 1110 ) is formed from the electrostrictive material. Clamping device according to one of the preceding claims, characterized characterized in that the electrostrictive material is selected made of: piezoelectric materials, carbon nanotubes and the like.