DE102017222774A1 - Method for clamping a workpiece in a clamping device and clamping device - Google Patents

Abstract

The present invention relates to a method of clamping a workpiece (5) in an open fixture (101), comprising the steps of providing the open fixture (101) with an open chamber (8), the open chamber (8) being in its interior molded body (11), positioning the workpiece (5) in the open jig (101), applying the shaped bodies (11) to a workpiece surface, and applying pressure or force to the shaped bodies (11) for fixing the workpiece (5) in the workpiece open clamping device (101). The present invention further relates to a method for clamping a workpiece (5) in a closed clamping device (100). Furthermore, the present invention relates to an open clamping device (101) for clamping workpieces to be machined (5), wherein the open clamping device (101) has an open chamber (8) whose inner volume has at least one open side (19), wherein the open Chamber (8) in its inner mold body (11) comprises, and wherein the moldings (11) are pressurizable, so that the workpiece (5) by means of form-fitting on the workpiece surface can be applied and pressurized form body (11) in the open clamping device (101) clamped is. Likewise, the present invention relates to a closed clamping device (100) for clamping of workpieces to be machined (5).

Description

The present invention relates to a method for clamping a workpiece in an open clamping device according to the preamble of claim 1 and a method for clamping a workpiece in a closed clamping device according to the preamble of claim 2. Furthermore, the present invention relates to an open clamping device according to claim 5 and a closed clamping device according to claim 6.

Workpieces with complex and irregularly shaped surfaces are usually clamped in a jig for machining in order to be processed by means of suitable tools. These surfaces can be, for example, free-form surfaces of curved, flow-optimized blade profiles for turbomachines. There are various devices and methods in the prior art for clamping workpieces having complex and irregularly shaped surfaces, for example a positive casting or embedding of the workpiece in a plastic and subsequent machining of a remaining area of the workpiece. Another method is the vacuum clamping of workpieces. Likewise, frictional (jaws, collets) and cohesive (eg gluing, soldering) clamping devices for various processing methods are disclosed in the prior art.

An object of the present invention is to propose a further method for clamping a workpiece in a clamping device. It is another object of the present invention to provide a clamping device for clamping of workpieces to be machined.

The object according to the invention is achieved by a method for clamping a workpiece in an open clamping device having the features of claim 1. It is further achieved by a method for clamping a workpiece in a closed clamping device with the features of claim 2, an open clamping device with the features of claim 5 and a closed clamping device with the features of claim 6.

The invention thus proposes a method for clamping a workpiece in an open clamping device. In a first method step, a clamping device with an open chamber is provided. The chamber can be referred to as a hollow body with an opening. The opening can be described as the open side of the chamber. The chamber is therefore not completely enclosed or closed. The chamber has in its interior molded body. The moldings may be referred to as mold elements. Shaped bodies are for example balls, which can be hollow or solid inside.

In a second method step, a workpiece is positioned in the clamping device. The workpiece has in particular curved, curved or complex shaped surfaces such as free-form surfaces for editing. The workpiece may purely by way of example be a moving blade or a guide vane of a turbomachine.

In a third method step, the shaped bodies, in particular on or along the open side of the chamber, are applied to a workpiece surface. An application can also mean a pressing, nestling or the like.

In a fourth method step, a pressure or a force is applied to the moldings located inside the chamber. By means of this pressure or this force, the workpiece is fixed in the clamping device. The application of the pressure may be gradual (for example stepwise), so that first the loose and disorderly present in the chamber shaped body are transferred by means of pressure in a dense composite of moldings in which the moldings no longer or at least only slightly move against each other can. This dense composite can be referred to as dense packing. Up to this pressure stage substantially no pressure for fixing the workpiece is applied against the moldings. In the next subsequent pressure step, this pressure is then increased and the workpiece is fixed in position by means of the shaped bodies. The said pressures can be applied linearly and continuously or discontinuously.

According to the invention, a further method for clamping a workpiece in a closed clamping device is proposed, which provides a clamping device with a closed chamber in a first step. The closed chamber can be referred to as a hollow body. The chamber is at least partially closed by a membrane. Closing the chamber through the membrane may also mean limiting, enclosing or abutting. The chamber has in its interior molded body. The moldings may be referred to as mold elements. Shaped bodies are for example balls, which can be hollow or solid inside.

In a second method step, a workpiece is positioned in the clamping device. The workpiece has in particular curved, domed or complex shaped surfaces such as freeform surfaces for machining. The workpiece may purely by way of example be a moving blade or a guide vane of a turbomachine.

In a third method step, the membrane is applied to a workpiece surface. An application can also mean a pressing, nestling or the like. For example, the membrane can advantageously be applied to a workpiece surface designed as a free-form surface. Thus, a direct positive connection between the workpiece surface and the membrane can be generated.

In a fourth method step, a pressure or a force is applied to the moldings located inside the chamber. By means of this pressure or this force, the workpiece is fixed in the clamping device. The application of the pressure may be gradual (for example stepwise), so that first the loose and disorderly present in the chamber shaped body are transferred by means of pressure in a dense composite of moldings in which the moldings no longer or at least only slightly move against each other can. This dense composite can be referred to as dense packing. Up to this pressure stage substantially no pressure for fixing the workpiece is applied to the membrane. In the next, subsequent pressure step, this pressure is then increased and the workpiece is fixed in position by means of the membrane. The said pressures can be applied linearly and continuously or discontinuously.

The open clamping device according to the invention is designed and prepared for, in particular releasable, clamping of workpieces to be machined. The clamping device can be referred to as a workpiece receiving device or as a flexible mold clamping system. The clamping can be referred to as fixing. The tensioning device has an open chamber, that is, at least one side or a portion of the chamber is open. In the chamber moldings are arranged for abutment against at least one workpiece surface. The shaped bodies can be created directly on a surface of the workpiece by means of the open chamber. The moldings can be pressurized, so that the workpiece can be clamped in the clamping device by means of the moldings which can be pressurized.

The closed clamping device according to the invention is designed and prepared for, in particular releasable, clamping of workpieces to be machined. The clamping device can be referred to as a workpiece receiving device or as a flexible mold clamping system. The clamping can be referred to as fixing. The tensioning device has at least one membrane for contacting the membrane with at least one workpiece surface. The chamber comprises in its interior pressurizable moldings, by means of which the workpiece can be clamped in the clamping device by means of the membrane which can be placed on the workpiece surface in a form-fitting manner and by means of the moldings which can be pressurized.

Advantageous developments of the present invention are the subject of subclaims and embodiments.

Inventive exemplary embodiments may have one or more of the following features.

A clamping of a workpiece in a clamping device is to be understood as a clamping, fixing, clamping or the like of the workpiece in the clamping device.

A workpiece may be any object that may be made of a solid material and is to be machined in some way. The machining can be material-removing, for example by means of milling, grinding, laser machining or by means of another machining method.

A chamber may be a closed or open chamber, a pressure chamber, a cavity or the like. The chamber may be partially closed by the membrane. Completion may mean enclosing the chamber in one or more areas. The chamber may have a, at least in sections, flexible envelope. Likewise, the chamber, at least in sections, have solid and stable areas or walls. The chamber may at least partially have a cylindrical shape. A cylindrical shape may have on one end face the membrane, on the opposite side a piston which is arranged displaceably against the chamber interior and thus can move the membrane. The piston can for example be moved and driven by means of a piston rod, a threaded rod or the like.

A membrane may, in some exemplary embodiments of the invention, be a moveable, flexible structural element that terminates the chamber in sections. The membrane can be stretchable. The membrane can close and seal the chamber to the outside, ie to the outside of the chamber. By means of the membrane, a complex shaped workpiece clamped in the clamping device and form fit be fixed. A positive clamping can mean or comprise a surface clamping by means of the membrane. A complex-shaped workpiece, for example, a workpiece with convex and / or concave surfaces, which may be configured as free-form surfaces. By way of example only, a complex shaped workpiece may be a blade or vane of a turbomachine, particularly an axial gas turbine.

The chamber has in its interior molded body, which can be referred to as a packing. The moldings may be geometrically uniform or differently configured components. For example, the shaped bodies may be spherical, polyhedral or prismatic. Balls may have the same or different diameters. The shaped bodies can be hollow or solid inside. In particular, the shaped bodies have a smooth outer surface, so that the shaped bodies can easily be displaced relative to one another. As a result, the moldings can easily move in the chamber at a pressure applied from the outside against each other and push together to form a tight package. By means of this dense packing, a pressure applied from the outside to the chamber can be transmitted and exerted on the membrane and on the workpiece resting against the membrane. As a result, advantageously a complex-shaped workpiece can be easily and releasably clamped and fixed.

The moldings can have a flexible shape in an unloaded state and a dimensional stability in a loaded state. In particular, the moldings are deformable, but not compressible.

In some exemplary embodiments of the invention, the moldings are made of metal, ceramic, plastic, and / or composite material, or include such material.

The membrane may be functionally described as shielding the filling material from the surrounding space. The ambient space may be referred to as engine room.

Positioning of the workpiece in the chuck and subsequent application of the membrane to the workpiece surface, in some exemplary embodiments of the invention, may mean that the workpiece is fixed and held with a low bias on the diaphragm in the chuck, but shifting and accurately positioning the workpiece Workpiece for a subsequent processing step is still possible. Based on the, in particular flexible, membrane and the shaped bodies in the chamber, the membrane is also in a displacement and positioning of the workpiece before and after the displacement of a form-fitting manner on the workpiece surface, or at least portions of it. In a subsequent increase of the pressure on the chamber with the moldings, and thus on the membrane, the workpiece can be finally clamped and fixed without the workpiece again, even slightly, moves. For a largely accurate machining of the workpiece in a subsequent step is possible.

In some exemplary embodiments of the invention, pressure may be exerted on the moldings to fix the workpiece in the chuck by means of a plate, a punch, one or more expandable tubing, another membrane, or the like.

In some exemplary embodiments according to the invention, in a further method step, the workpiece in the clamping device can be processed by means of a material-removing method. Due to the previously performed method step of applying a pressure or a force on the moldings for fixing the workpiece in the clamping device and a positive engagement of the membrane on at least a portion of the workpiece surface can advantageously be achieved vibration damping of the workpiece during a processing step. The vibration damping can also be influenced by a suitable choice of the moldings in the chamber. Depending on the size, shape and material selection of the molded body, a targeted vibration damping can be set, which is tuned, for example, to the natural frequencies of the workpiece to be machined. This can advantageously ensure a high machining accuracy of the workpiece. Thus, the moldings can act vibration damping in the chamber, especially during the application of a material-removing machining process.

In some exemplary embodiments of the invention, the application of pressure or force to the moldings is pneumatic or hydraulic. A pneumatic pressure application can be made by means of a flexible hose or a flexible chamber, wherein the hose, the chamber or another form can be pneumatically controlled or regulated filled and emptied. For example, a pneumatically filled tube can build up a pressure that can be transferred to the chamber with the moldings. As a result, in turn, the membrane can be positively applied to the workpiece surface and pressed and thus clamp the workpiece in the clamping device and fix. Instead of a pneumatic system can also hydraulic system can be used. The control mechanisms and / or the control mechanisms for such systems are known in the art.

In some exemplary embodiments of the invention, the application of pressure or force to the moldings is mechanical. Mechanical pressure application may be by means of a spindle-plate arrangement, a piston-piston rod arrangement, a gear arrangement or the like.

In some exemplary embodiments according to the invention, the clamping device is provided and prepared for clamping workpieces to be machined by means of material-removing methods. Material removing processes are, for example, cutting, milling or grinding processes, laser-based processes or other processes.

The workpieces to be machined may have free-form surfaces as surfaces, which can advantageously be clamped and fixed in an easily positionable manner by means of the clamping device according to the invention.

In some exemplary embodiments according to the invention, the membrane of the tensioning device has one or more, in particular multilayer, flexible layers. The chamber with the membrane can be referred to as a shape-changing holding section, since the membrane can adapt to differently shaped workpiece surfaces.

In some exemplary embodiments of the invention, the chamber further comprises a fluid adjacent to the moldings. The fluid may be gaseous or liquid. The fluid may be a liquid medium, such as water or a viscous, viscous liquid, or a viscous liquid that is lower in water. The fluid may be a gel or a suspension. The selection of a suitable fluid can be matched to the choice of material and / or the surface quality of the molded bodies, for example to optimize a damping function and / or a support function of the clamping device. This optimization may further involve the workpiece geometry and / or the workpiece material. The fluid may comprise a gel and / or a liquid and / or small, granular particles such as sand and / or steel balls.

In some exemplary embodiments according to the invention, the workpiece can be clamped positively and non-positively in the clamping device by means of the membrane which can be applied to the workpiece surface and by means of the pressure-susceptible shaped bodies. The positive connection can be achieved by applying the flexible membrane to a free-form surface of the workpiece. The frictional connection can be achieved by a force exerted on the chamber and the moldings located in the chamber. A combination of positive engagement and frictional engagement can produce a stable and positionally correct positioning of the workpiece in the clamping device.

In some exemplary embodiments according to the invention, the tensioning device has a hydraulic or a pneumatic or a mechanical system for pressurizing the shaped bodies. The systems can also be used in combination. The system may include a hose having a pneumatic interface to pressurize the chamber. The hose can be stretchable.

The internal pressure of the hose leads to a volume displacement outside of the hose. This volume displacement acts on the moldings in the chamber. The moldings may be referred to as damping material. The shaped bodies act on the workpiece via the membrane, for example a clamped housing. In particular, an energy absorption and a supporting function of the workpiece advantageously take place at the same time. The described arrangement can be referred to as a multi-chamber arrangement or as a multi-chamber ring.

The pneumatic interface may include control valves for generating an overpressure (for clamping the workpiece) and for generating a negative pressure (for releasing and removing the workpiece).

In some exemplary embodiments of the invention, the chamber has at least one piston or plunger for pressurizing the moldings.

In some exemplary embodiments according to the invention, the clamping device has two clamping jaws for clamping a workpiece. The clamping jaws can be moved hydraulically, pneumatically or mechanically. The clamping jaws can be driven and moved manually or automatically.

In some exemplary embodiments of the invention, the tensioner comprises a magnetorheological fluid. A magnetorheological fluid may comprise a carrier fluid having finely divided solid particles. By means of a magnetorheological fluid can advantageously by means of an applied current a Workpiece be clamped in the jig. Furthermore, the vibrations of the clamped workpiece can be influenced by means of an applied current.

In some example embodiments of the invention, the tensioner is an assembly for lifting objects. Likewise, in some exemplary embodiments of the invention, a tensioning device is an arrangement for lifting and then moving objects, for example, from one position to another position.

Some or all embodiments according to the invention may have one, several or all of the advantages mentioned above and / or below.

By means of the clamping device according to the invention workpieces can be advantageously easily clamped with highly complex Konturzügen the workpiece surfaces. Simple clamping requires, for example, little or no preparation processes and / or subsequent processes, as is necessary, for example, in alternative clamping devices by gluing or pouring of the workpieces.

By means of the clamping device according to the invention geometric tolerances of a manufacturing process of a workpiece to be fixed can be compensated advantageous. For example, casting tolerances of a cast workpiece can be compensated for by means of the adjacent shaped bodies on the workpiece or an adjacent membrane on the workpiece. An alternative exact, contour-faithful clamping device, which would have to be produced consuming, can be advantageously avoided.

The method according to the invention for clamping a workpiece in the clamping device can advantageously reduce set-up times compared with alternative clamping methods.

By means of the tensioning device according to the invention, a force transmission to the workpiece can advantageously be transmitted without high voltage peaks (on the workpiece surface). The membrane of the clamping device allows, at least in sections, flat concerns on the workpiece surface. The force transmission of the forces acting on the moldings of the chamber forces can be transmitted by means of the membrane advantageously without high voltage spikes on the workpiece.

The clamping device according to the invention advantageously allows a positive connection between the membrane of the clamping device and the workpiece to be clamped.

In some embodiments, application of a workpiece to the diaphragm may advantageously act to dampen vibration and / or vibration on the workpiece. This can improve the manufacturing accuracy in a machining step of a clamped workpiece.

By means of the method according to the invention for clamping a workpiece in the clamping device, the frequency detuning of the clamping device can be advantageously adapted. In particular, by the shaped body inside the chamber, this frequency detuning can be done. Depending on the size, shape, material, surface design, etc. of the molded body, for example, the natural frequency of the clamping device can be influenced and selectively changed. Due to the clamping of a workpiece by means of the membrane, the frequency detuning of the entire unit of clamping device and workpiece can also be influenced. This allows an accurate and low-vibration machining of a material-removing process, for example, in a milling, wherein the cutter generates certain frequencies due to its dynamics.

The tensioning device according to the invention advantageously makes possible a combination of, on the one hand, damping of vibrations of the tensioning device or of individual parts of the tensioning device and, on the other hand, support or clamping of a workpiece with detuning with regard to component vibrations. The introduction of force to the chamber and the moldings contained therein on the one hand leads to clamping (or supporting) of the workpiece and on the other hand to damping of the overall arrangement. In particular, by a suitable choice of the size, the shape, the materials and / or the surface design of the molded body in the chamber, this combination of a damping and a support with a detuning can be achieved. The choice of material for the moldings is largely freely selectable. This choice of material essentially determines or influences the natural frequency of the components.

The clamping device according to the invention advantageously allows due to the membrane chamber arrangement a high insensitivity to contamination of the clamping device, in particular in the interior of the chamber with the moldings. The membrane largely shields these shaped bodies in the chamber. Thus, for example, removed chips in a milling of the workpiece, optionally additionally mixed with a lubricant and / or a coolant (for example, oil as a cooling fluid), further optionally grinding dust and / or Schleifscheibenabrieb, do not get into the interior of the chamber. This can be advantageously eliminated consuming, subsequent cleaning times or at least shortened. This can advantageously lead to a cost saving of the entire processing time in the material-removing machining of the workpiece by means of the clamping device according to the invention.

The clamping device according to the invention advantageously makes it possible to prevent damage to the workpiece, due to a suitable choice of material of the membrane and, at least in sections, planar engagement of the membrane on the workpiece.

The method according to the invention advantageously makes possible an automatable method for clamping and machining workpieces.

• 1 zeigt eine erfindungsgemäße geschlossene Spannvorrichtung mit zwei Spannbacken und einer eingespannten Turbinenschaufel im Querschnitt;
• 2a,b,c zeigen schematisch verschiedene Anordnungen von Kugeln als Formkörper an einer Membran;
• 3 zeigt den Verlauf einer Flächenpressung zwischen einem Flächenausschnitt des Bauteils und einer Membran über einem Spindelmoment;
• 4 zeigt die Verfahrensschritte zum Spannen eines Werkstücks in einer geschlossenen oder offenen Spannvorrichtung; und
• 5 zeigt eine erfindungsgemäße offene Spannvorrichtung mit zwei Spannbacken und einer eingespannten Turbinenschaufel im Querschnitt.

The present invention will be explained in the following with reference to the accompanying drawings, in which identical reference numerals designate identical or similar components, by way of example. In each case greatly simplified schematic figures:

• 1 shows a closed clamping device according to the invention with two clamping jaws and a clamped turbine blade in cross section;
• 2a, b , c show schematically various arrangements of balls as shaped bodies on a membrane;
• 3 shows the course of a surface pressure between a surface section of the component and a membrane over a spindle torque;
• 4 shows the method steps for clamping a workpiece in a closed or open clamping device; and
• 5 shows an open clamping device according to the invention with two clamping jaws and a clamped turbine blade in cross section.

1 shows a clamping device according to the invention 100 with two jaws 1 . 3 and a clamped turbine blade 5 as a workpiece in cross section. The jaws 1 . 3 each have a closed chamber 7 on, by means of a membrane 9 is completed. The closed chamber 7 includes inside moldings 11 , which in this embodiment exemplarily as spheres 11 are executed. The balls 11 are by means of a stamp-shaped or piston-shaped plate 13 and a pestle 15 be pressurized. When on the pestle 15 a force in the direction of the plate 13 is exercised, the bullets become 11 by means of the pressure of the plate 13 pushed together.

The two jaws 1 . 3 Can be used to clamp and re-release the turbine blade 5 in the direction of the arrows 17 to be moved. For the sake of simplicity, the following description will be applied to one of the two jaws 1 . 3 based. Analogously, however, the description applies to both jaws 1.3. Before the membrane 9 on the example of the turbine blade shown here 5 as a workpiece, the balls are 11 disordered and without pressurization by the plunger 15 and the plate 13 in the chamber 7 distributed. After the closed chamber 7 with the membrane 9 to the turbine blade 5 introduced or moved up, the balls are 11 initially without pressurization on the membrane 9 on. In this condition is the turbine blade 5 not yet fixed and not yet clamped. Only in the subsequent process step is by means of the plunger 15 and the plate 13 Pressure on the balls 11 in the closed chamber 7 exercised, so the balls 11 as a tight pack (in 1 as ball packing or ball package) largely flat pressure on the membrane 9 and the turbine blade 5 exercise. Depending on the pressure application, the turbine blade 5 now fixed and clamped. Subsequently, a processing step, for example, a milling, a remaining free surface of the turbine blade 5 respectively. Optionally, the turbine blade 5 be clamped segment by segment to machine the free, unrestrained segments, or the entire surface of the turbine blade 5 is clamped, for example, a blade root or an end face of the turbine blade 5 to edit. The turbine blade 5 may have concave and convex blade sides, which may also have complex free-form surfaces.

By means of the closed clamping device according to the invention 100 Advantageously, any workpieces, in particular workpieces with free-form surfaces, can be clamped with exact position. During the clamping process, the workpiece is fixed in position without the workpiece shifting due to possible pressure peaks or force peaks with alternative clamping devices. The balls 11 can, depending on the pressure application, for example, with a designed as a spindle ram assembly, high surface pressures over the membrane 9 on the turbine blade 5 exercise and thus achieve a high clamping effect.

By means of the closed clamping device according to the invention 100 can further advantageous possible vibrations of the workpiece, here the turbine blade 5 which may occur in an exemplary milling, in particular by means of the balls 11 be reduced and dampened. The balls 11 Depending on the workpiece geometry, workpiece material, machining method, etc. can be selected specifically to achieve a high damping of vibrations. Likewise, the Natural frequency of the workpiece to be considered in the selection of the shaped body. The moldings can be specifically selected in their shape, in their material, their surface finish, etc., for the intended use.

As in 1 shown, the jaws can 1 . 3 individually to the workpiece shape, such as in the embodiment of the 1 illustrated shape of the turbine blade 5 , be adjusted.

2a, b , c show schematically different arrangements of balls 11 as a shaped body on a membrane 9 ,

2a shows loose balls 11 that are not directly on the membrane 9 issue. The freedom of movement of the form body 11 is indicated by the arrows in different directions. The balls 11 have all degrees of freedom to move on. There is no pressure effect on the balls 11 instead of. In this state, no workpiece is clamped. The balls 11 may be dispersed in a liquid or gaseous fluid, for example in water, oil. The balls 11 have a loose, fluid-like behavior, relative movements of the balls 11 with each other are possible.

2 B shows the balls 11 loosely attached to the membrane 9 abut or move towards the membrane 9 move. In this state, a pressure on the balls 11 built without causing surface pressure on the membrane 9 is exercised. A one-sided pressure, represented by the arrows, begins. A workpiece may already be loose on the membrane 9 concerns (in 2 B not shown). A process of nestling the balls 11 and the membrane 9 to a counter contour takes place, for example, continuously or stepwise. At the end of the process, there is no movement within the bond of the balls 11 more is possible.

2c shows the balls 11 attached to the membrane 9 be pressed and thus lie close to her. There is a two-sided force (or pressure), represented by the two opposite arrows. In other words, the tension and counterforce are delivered by the workpiece. The power transmission is largely over the entire surface of the membrane 9 ,

3 shows the graph of a surface pressure P [MPa] between a surface section of the component (workpiece) and a membrane over a spindle torque M [Nm]. The spindle torque M can via a spindle analogous to a plunger 15 (please refer 1 ) are applied.

The surface pressure P behaves asymptotically to the spindle torque M. This means that the surface pressure P increases initially with increasing spindle torque M steeply, which is the beginning of a one-sided pressure on the membrane 9 can be explained (see 2 B) , With a further increasing spindle moment M, the balls arrange themselves into a dense packing, the surface pressure P on the membrane flattens according to the graphic progression of 3 from.

In this graphical course of a surface pressure P [MPa] between the workpiece and the diaphragm over a spindle torque M [Nm], spheres are assumed as shaped bodies purely by way of example. The grade of the balls should be as good as possible. The grade is defined at least in terms of roughness, a polished surface, a high dimensional stability and a uniformity of the balls. Increased roughness would disturb and negatively influence the force course and the setting behavior of the balls in a spherical packing. A so-called "whetting" of the balls on the membrane would lead to a "fatigue" of the balls.

4 shows the method steps for clamping a workpiece in a clamping device. The method includes the steps of providing S1 a tensioning device 100 with a chamber 7 and one this chamber 7 at least partially final membrane 9 , where the chamber 7 in its interior molded body 11 has, positioning S2 of the workpiece 5 in the tensioning device 100 , Invest S3 the membrane 9 to a workpiece surface and applying S4 a pressure or a force on the moldings 11 for fixing the workpiece 5 in the tensioning device 100 ,

5 shows an open clamping device according to the invention 101 with two jaws 1 . 3 and a clamped turbine blade 5 in cross section.

The jaws 1 . 3 each have an open chamber 8th on, each one to the clamped turbine blade 5 aligned open side 19 having. So they are as balls 11 executed moldings 11 directly on the workpiece, which in this exemplary embodiment a turbine blade 5 is on.

The one in the open chamber 8th arranged balls 11 are by means of a stamp-shaped or piston-shaped plate 13 and a pestle 15 be pressurized. When on the pestle 15 a force in the direction of the plate 13 is exercised, the bullets become 11 by means of the pressure of the plate 13 pushed together.

The two jaws 1 . 3 Can be used to clamp and re-release the turbine blade 5 in the direction of the arrows 17 to be moved. For the sake of simplicity, the following description will be applied to one of the two jaws 1 . 3 based. Analogously, however, the description applies to both jaws 1.3.

Before the balls 11 on the turbine blade 5 abut, they must be in the open chamber 8th be fixed or held against falling out. This can, for example, by means of a to the contour of the open side 19 customizable cover plate, the immediately before a pressure application and after a concern of the balls 11 on the turbine blade 5 from the space between the open side 19 and the surface of the turbine blade 5 is pulled out. Then the balls are lying 11 initially without pressurization on the surface of the turbine blade 5 on. In this condition is the turbine blade 5 not yet fixed and not yet clamped. Only in the subsequent process step is by means of the plunger 15 and the plate 13 Pressure on the balls 11 in the closed chamber 7 exercised, so the balls 11 as a tight pack (in 1 as ball packing or ball package) largely flat pressure on the turbine blade 5 exercise. Depending on the pressure application, the turbine blade 5 now fixed and clamped. Subsequently, a processing step, for example, a milling, a remaining free surface of the turbine blade 5 respectively. Optionally, the turbine blade 5 be clamped segment by segment to machine the free, unrestrained segments, or the entire surface of the turbine blade 5 is clamped, for example, a blade root or an end face of the turbine blade 5 to edit. The turbine blade 5 may have concave and convex blade sides, which may also have complex free-form surfaces.

By means of the open clamping device according to the invention 101 Advantageously, any workpieces, in particular workpieces with free-form surfaces, can be clamped with exact position. During the clamping process, the workpiece is fixed in position without the workpiece being displaced due to possible pressure peaks or force peaks with alternative clamping devices. The balls 11 can, depending on the pressure application, for example, with a designed as a spindle ram assembly, high surface pressures over the membrane 9 on the turbine blade 5 exercise and thus achieve a high clamping effect.

By means of the open clamping device according to the invention 100 can further advantageous possible vibrations of the workpiece, here the turbine blade 5 which may occur in an exemplary milling, in particular by means of the balls 11 be reduced and dampened. The balls 11 Depending on the workpiece geometry, workpiece material, machining method, etc. can be selected specifically to achieve a high damping of vibrations. Likewise, the natural frequency of the workpiece can be taken into account in the selection of the shaped body. The moldings can be specifically selected in their shape, in their material, their surface finish, etc., for the intended use.

As in 5 shown, the jaws can 1 . 3 individually to the workpiece shape, such as in the embodiment of the 5 illustrated shape of the turbine blade 5 , be adjusted.

LIST OF REFERENCE NUMBERS

r

radial

100

closed clamping device

101

open clamping device

1

jaw

3

jaw

5

turbine blade

7

closed chamber

8th

open chamber

9

membrane

11

Shaped body, ball

13

Plate, stamp, pistons

15

tappet

17

Arrow, direction of movement of the clamping jaws

19

open side of the chamber

Claims (12)

Method for clamping a workpiece (5) in an open clamping device (101), comprising the following steps: - providing the open clamping device (101) with an open chamber (8), wherein the open chamber (8) in its inner molded body (11 ) having; - Positioning the workpiece (5) in the open clamping device (101); - applying the moldings (11) to a workpiece surface; - Applying a pressure or a force on the moldings (11) for fixing the workpiece (5) in the open clamping device (101). Method for clamping a workpiece (5) in a closed clamping device (100), comprising the following steps: - Providing the closed clamping device (100) with a closed chamber (7) and a closed chamber (7) at least partially final membrane (9), wherein the closed chamber (7) in its interior molded body (11); - Positioning the workpiece (5) in the closed clamping device (100); - applying the membrane (9) to a workpiece surface; - Applying a pressure or a force on the moldings (11) for fixing the workpiece (5) in the closed clamping device (100). Method according to Claim 1 or 2 with the further step: - processing the workpiece (5) in the open or closed clamping device (100, 101) by means of a material-removing method. Method according to one of the preceding claims, wherein the application of the pressure or the force on the moldings (11) takes place pneumatically, hydraulically, mechanically or electrically. Open clamping device (101) for clamping workpieces (5) to be machined, wherein the open clamping device (101) has an open chamber (8) whose internal volume has at least one open side (19), characterized in that the open chamber (8 ) in its inner mold body (11), wherein the moldings (11) are pressurizable, so that the workpiece (5) can be clamped in the open clamping device (101) by means of the mold body (11) which can be form-fitted on the workpiece surface and pressurized. Closed clamping device (100) for clamping of workpieces to be machined (5), wherein the closed clamping device (100) has a membrane (9) for their concern on at least one workpiece surface, and the membrane (9) a chamber (7) at least partially closes , characterized in that the chamber (7) in its inner mold body (11), wherein the moldings (11) are druckbeaufschlagbar, so that the workpiece (5) by means of the form-fitting can be applied to the workpiece surface membrane (9) and by means of the pressurizable moldings (11) in the clamping device (100) can be clamped. Clamping device (100, 101) according to Claim 5 or 6 , wherein the shaped bodies (11) are spherical, polyhedron-shaped or prism-shaped. Clamping device (100, 101) according to one of Claims 5 to 7 , wherein the shaped bodies (11) are made of metal, of ceramic, of plastic and / or of a composite material or comprise such a material. Clamping device (100, 101) according to one of Claims 5 to 8th wherein the tensioning device (100) comprises a hydraulic or a pneumatic or a mechanical system for pressurizing the shaped bodies (11). Clamping device (100, 101) according to one of Claims 5 to 9 , wherein the open or closed chamber (7, 8) has at least one plate (13) for pressurizing the moldings (11). Clamping device (100, 101) according to one of Claims 5 to 10 , wherein the clamping device (100, 101) has two clamping jaws (1, 3) for clamping a workpiece (5). Clamping device (100, 101) according to one of Claims 5 to 11 , wherein the clamping device (100, 101) is designed in an annular manner for clamping a workpiece (5).

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