CLAMPING DEVICE, MACHINE TOOL, MANUFACTURING PLANT AND METHOD FOR MAKING A WORKPIECE

Description

[0001] The present disclosure relates to a clamping device for holding a workpiece to be machined, a combination of such a clamping device and a workpiece, a machine tool equipped with such a clamping device, a production plant with at least one machine tool, and a method for manufacturing a workpiece, in particular by machining. In exemplary embodiments, the present disclosure relates to the machining of impellers, compressor wheels, rotors, turbine wheels, vane wheels, and the like.

[0002] From WO 2009 / 106268 A2, a machine tool for machining a workpiece having a central bore is known, comprising a tool holder for holding a tool, a workpiece support for placing the workpiece, a workpiece holder for holding the workpiece, and a drive means for rotating the workpiece about a central axis of rotation, wherein the workpiece support has a mandrel for positively locking the workpiece, such that a section of the mandrel projects into the bore on a first side of the workpiece, and wherein the workpiece holder has a counter-holder movable in the direction of the bore axis of the central bore for applying a contact pressure to the workpiece on a second side opposite the first side, acting in the direction of the bore axis.

[0003] The machine tool is suitable for manufacturing workpieces with complex geometries, such as impellers, compressor wheels, turbine wheels, propellers, and the like. These workpieces are used, for example, in turbomachinery. Typically, the workpieces have an axis of rotation and a plurality of blades distributed around this axis. The blades can also be referred to as vanes or wings. Such workpieces exhibit complex geometries with curvatures along multiple axes. WO 2009 / 106268 A2 is suitable for machining one side of the workpiece to form complex blade geometries.

[0004] In exemplary embodiments, the present disclosure relates to workpieces in which an integral design consisting of hub and blades is present. For example, a one-piece body is provided which is produced by machining from a solid semi-finished product. In exemplary embodiments, the present disclosure relates to workpieces milled from solid material.

[0005] WO 2004 / 012899 A2 discloses a device for clamping rotationally symmetrical workpieces, suitable for machining the back side of a workpiece that has already been machined on the opposite side. The device comprises a drawbar that engages in a hub of the workpiece and engages behind an undercut contour. The design resembles a bayonet fitting. In this way, the workpiece can be clamped axially. However, WO 2004 / 012899 A2 does not address the high-precision rotational alignment between the front and back sides of the workpiece. It merely suggests using a cast-in mark at the workpiece hub. This approach is not suitable for workpieces where the outer contour of the hub is machined externally.

[0006] US Patent 2010 / 126015 A1 discloses a device for aligning / fixing an impeller for repair purposes, which uses a toothed disc.

[0007] It has become apparent that there is an increasing demand for workpieces that require machining on both a first side (e.g., front) and a second side (e.g., back). The terms "first side / front" and "second side / back" primarily refer to the order of machining. These terms serve primarily to distinguish between the two sides and should not be interpreted restrictively.

[0008] A continuous circular or ring-shaped wall is typically provided between the two sides. Starting from this wall, blades and similar contours can be formed on the front and back. Machining takes place on both sides, for example, adjacent to a front and rear end of a workpiece hub.

[0009] For example, the arrangement known from WO 2009 / 106268 A2 allows for extensive machining of the first side (front) of a workpiece in the form of a compressor wheel or impeller. However, since the workpiece is fixed to a clamping device with its second side (back), this side may not be readily accessible for machining.

[0010] Machining the second side may require repositioning the workpiece. There are often specifications for the rotational alignment (orientation) between the first and second sides. In other words, for example, blades on the second side should be aligned in a specific way with blades on the first side. This alignment may need to be highly precise. Therefore, there may be specific specifications for the rotational orientation (angular alignment) between the first and second sides of such workpieces, which must be observed during manufacturing.

[0011] For example, the rotational orientation can be lost when the workpiece is repositioned between the first and second sides. The rotational orientation of the workpiece can, in principle, be determined using suitable measuring technology. However, this increases the manufacturing effort (setup time).

[0012] Against this background, the present disclosure aims to provide a clamping device for holding a workpiece to be machined, a machine tool equipped with such a clamping device, a production plant with at least one machine tool, and a method for producing a workpiece, in particular by machining, which allow for highly accurate placement and orientation of the workpiece. Preferably, highly accurate and precise placement and rotational alignment with high repeatability is ensured. In particular, the clamping device should allow for the optimization of cycle times in series production. Preferably, the clamping device should support the multi-sided or all-around machining of impellers, compressor wheels, and similar workpieces.The clamping device should preferably enable a highly accurate rotational alignment of a workpiece via its previously machined front side, so that the back side can be machined in precise rotational alignment with respect to the front side.

[0013] According to a first aspect, the present disclosure relates to a clamping device for receiving a workpiece to be machined, in particular for machining an impeller to be machined on both sides, which has the following features: a workpiece holder rotatably driven about a longitudinal axis with a workpiece support, a hold-down clamp which is opposite the workpiece support in at least one clamping position in order to clamp a workpiece provided with a centering recess concentrically to the longitudinal axis between the workpiece support and the hold-down clamp, and a rotation orientation contour which is arranged at the workpiece support and provides at least one rotation stop for an orientation section of the workpiece for rotational alignment of the workpiece in the clamping position, wherein the rotation orientation contour comprises a crown surrounding the longitudinal axis, and wherein the at least one rotation stop is formed at a tooth of the crown.

[0014] The clamping device allows not only axial fixation but also a defined rotational orientation of the workpiece. This enables the repeatable positioning of workpieces within a series, thereby increasing overall manufacturing quality. When the workpiece is clamped (clamped position), the side facing the hold-down device (second side / back) can be machined. For example, this side (second side / back) could be a side that, in a previous manufacturing step, faced a workpiece support within a clamping device. In other words, the workpiece is rotated, for instance, 180° around an axis perpendicular to its longitudinal axis.

[0015] In one exemplary embodiment, the workpiece's orientation section is radially spaced from the workpiece's hub. In another exemplary embodiment, a previously machined contour serves as the orientation section. When machining a second side of the workpiece, this can be a contour previously created during the machining of the first side.

[0016] The workpiece is designed, for example, as an impeller, compressor wheel, rotor, fan wheel, paddle wheel, or the like. In one exemplary embodiment, the workpiece in its final state is provided with a blade contour on both a first and a second side. The clamping device according to the disclosure facilitates the machining of the second side, which may be difficult to access during the machining of the first side. Accordingly, the clamping device according to the disclosure can be described as a secondary clamping device or as a clamping device for the second side; however, this is not to be understood as a limitation.

[0017] The rotation orientation contour has at least one stop for a corresponding orientation section of the workpiece. This allows workpieces to be clamped with repeatable accuracy in the desired rotation orientation. The workpiece's centering recess is specifically aligned concentrically to the longitudinal axis of the workpiece holder.

[0018] This clamping device is particularly suitable for workpieces where single-setup machining is not economically viable. The device ensures the required centering (very precise concentricity) during machining of both the first and second sides. Furthermore, it is ideal for complex geometries that cannot be easily clamped using standard clamping elements.

[0019] The workpiece's orientation section is created, for example, in a preceding manufacturing step, particularly in a different clamping setup. In one exemplary embodiment, the orientation section has at least a partially radial extent. For example, the orientation section is curved in two or three directions. The workpiece's orientation section contacts the rotary stop. The primary focus here is on the workpiece's rotational alignment. The actual clamping and torque transmission for rotational drive during machining can be achieved via other workpiece components (e.g., a hub).

[0020] The disclosure further relates to a combination of a clamping device according to one of the embodiments described herein and a workpiece, in particular in the form of an impeller to be machined on both sides, which is held therein, especially for machining purposes. The combination comprises the clamping device and the workpiece.

[0021] According to one exemplary embodiment, the rotational orientation contour has a plurality of rotational stops distributed around the longitudinal axis. Accordingly, the workpiece has a plurality of orientation sections. Support via a plurality of orientation sections distributed around the longitudinal axis (for example, formed on blades of the workpiece) improves the alignment and the ability to transmit force.

[0022] According to another exemplary embodiment, at least one rotary stop for aligning the workpiece is adapted to a blade of the workpiece. In other words, the orientation section of the workpiece is located, for example, on a blade of the first side previously produced in another clamping setup, which now faces the workpiece support.

[0023] According to another exemplary embodiment, at least one rotary stop is adapted to an edge of the blade. The edge is, for example, the rim of a blade with at least partial radial and at least partial axial extension. The edge is, for example, a relatively narrow surface that comes into contact with the rotary stop. The edge is, for example, spaced apart from a circumferential wall of the workpiece, which separates a first and a second side of the workpiece. From the perspective of the wall, the edge is, for example, the end of a blade extending from the wall that faces away from the wall. The edge is, for example, a contour on the first side of the workpiece that serves to align the workpiece when machining the second side.

[0024] For example, at least one orientation section is provided on one of the workpiece blades. For example, an orientation section is provided on multiple or all blades. For example, at least one orientation section is formed on the first side facing the workpiece support so that the second side facing away from the workpiece support can be machined. In exemplary embodiments, an existing blade contour is used for the orientation section. In other words, according to this embodiment, the orientation section does not need to be created separately. Rather, design features of the blades are taken into account, enabling highly precise rotational orientation in the clamping device.

[0025] According to a further exemplary embodiment, at least one rotary stop is adapted to an orientation section of the workpiece produced in another clamping setup, in particular to an edge of a blade formed on the workpiece.

[0026] The rotation orientation contour comprises a crown surrounding the longitudinal axis, with at least one rotation stop formed at a tooth of the crown. In other words, the rotation orientation contour is exemplified as a crown whose teeth / prongs face the retainer. In one exemplary embodiment, the rotation orientation contour is oriented concentrically to the longitudinal axis. In other exemplary embodiments, the rotation orientation contour is designed similarly to a crown wheel.

[0027] In another exemplary embodiment, the crown is attached to the workpiece holder in a replaceable manner. In other words, the crown can be detached from the workpiece holder. This allows the use of different types of rotational orientation contours / crowns. This enables the clamping device to be adapted to different workpieces. Furthermore, it allows for easy replacement of the crown in case of wear.

[0028] According to another exemplary embodiment, the crown has a plurality of teeth with rotation stops distributed around the longitudinal axis, with a gap for a measuring probe formed between at least two teeth. According to this embodiment, the rotational position of at least one of the rotation stops with respect to the longitudinal axis can be detected. This allows for so-called axis correction. In this way, the control system of a machine tool equipped with the clamping device receives information about the current rotational orientation of the crown and thus of a workpiece mounted on it. This can be used to align the rotational orientation of the first and second sides. In this way, the second side can be machined with high precision relative to the first side.

[0029] In other words, the workpiece's rotational position can be indirectly determined by measuring the crown's rotational position. Based on this, the workpiece's rotational position can be derived. However, it is also possible to determine the workpiece's rotational position using a reference workpiece (e.g., a reference part) if the probe contacts a defined contour of the workpiece (e.g., the reference part). After measurement and, if necessary, axis correction, subsequent parts can be machined without having to determine the rotational orientation each time.

[0030] According to a further exemplary embodiment, at least one tooth of the crown is adjacent to a support rib, wherein a gap is formed between the rotation stop of the tooth and the support rib, into which a blade of the workpiece is inserted in the clamping position, wherein the blade contacts the rotation stop with an edge, and wherein the support rib is formed on a support area spaced apart from the edge to support the blade.

[0031] In other words, a blade can be supported at the crown via the orientation section (for example, at an edge) and the support area (spaced from the edge). The rotation stop, relevant for the rotational orientation, is contacted by the orientation section. The support area is inclined relative to the longitudinal axis such that, when the support area rests against the crown, a force redirection occurs, pressing the workpiece's orientation section against the rotation stop. In this way, highly accurate and defined alignment can be ensured. The support area is provided, for example, on a blade surface of the workpiece facing the crown.

[0032] In one exemplary embodiment, several rotary stops and support ribs are distributed around the circumference of the crown. This allows the crown to effectively absorb forces applied when the workpiece is clamped. The workpiece can be held in the crown without play. The number of rotary stops and support ribs can be identical. However, a different number is also conceivable, for example, to provide a sufficiently wide rib for a measuring probe.

[0033] According to another exemplary embodiment, the support rib is designed to be flexible. For example, in the case of an axially pressing workpiece, the support rib can deflect at least partially towards the crown and towards the workpiece support. For example, the support rib is designed to be more flexible than the rotary stop. An inclined orientation of the support area ensures that a force component is still generated, which pushes the orientation section of the workpiece towards at least one rotary stop. For example, the support rib has a recess that ensures this flexibility. Alternatively, the support rib can be designed with a smaller cross-section (for example, parallel to the longitudinal axis) than the rotary stop.

[0034] In one exemplary embodiment, the crown has a circumferential base, with a plurality of rotation stops and a plurality of support struts extending from the base towards the hold-down.

[0035] According to another exemplary embodiment, the rotational orientation contour is made of a plastic material or an aluminum-based material. This applies particularly to the crown. This reduces the risk of damaging the workpiece.

[0036] According to another exemplary embodiment, the workpiece holder carries a centering mandrel which, in the clamping position, projects into the centering recess of the workpiece. In this way, axial centering is achieved not via the crown / rotational orientation contour, but via the central centering recess in the workpiece. Preferably, the centering recess of the workpiece serves for centering in a first position for machining the first side and in a second position for machining the opposite second side.

[0037] According to an exemplary embodiment, the centering mandrel centers the workpiece in a centering area of ​​the centering recess, with the workpiece's centering area being adjacent to the workpiece support in the clamping position. In other words, according to this embodiment, the centering area lies within a section of 0% to 30%, preferably 0% to 25%, more preferably a maximum of 20% of the longitudinal extent of the centering recess, extending from the workpiece holder towards the hold-down device. In this way, the workpiece can initially be easily placed onto a smaller-diameter insertion section of the centering mandrel. Centering only takes place in an end section of the centering mandrel near the workpiece holder. This simplifies automated clamping. For example, the centering mandrel has a receiving cone that simplifies alignment and assembly.

[0038] According to an exemplary embodiment, the centering mandrel has a contact surface on its end face, which is provided with a friction-enhancing coating, particularly a diamond coating. For example, the contact surface of one end face the hub of the workpiece. In the case of a friction-enhancing coating, the centering mandrel can transmit high torques even with a relatively low axial contact force. Preferably, the torque is transmitted primarily through the centering mandrel and only minimally via the rotational orientation contour (crown). The centering mandrel rests on an end face of the workpiece in a relatively small diameter area. A more or less complex vane contour is typically formed on the circumference of the end face, making support or rotation difficult there.

[0039] According to another exemplary embodiment, the hold-down device, in the clamping position, acts axially on a hub of the workpiece, in particular on an end face of the hub. In other words, the hold-down device presses axially on the hub facing away from the workpiece holder. The centering mandrel presses on the hub facing the workpiece holder. In one exemplary embodiment, the hold-down device does not engage in the centering recess of the workpiece, at least not for the purpose of centering. In this embodiment, centering is achieved on the workpiece holder side by the centering mandrel. The hold-down device secures the given position by applying a holding force that is essentially axial.

[0040] According to another exemplary embodiment, at least one airflow channel is formed in the rotational orientation contour, preferably with a plurality of openings directed towards the workpiece in the clamping position. In this way, air can be applied directly to the previously machined side of the workpiece for cleaning. The airflow can be directed directly onto blades of the workpiece. Openings for the airflow can be arranged, for example, between the rotational stops and / or the support ribs. Different rotational orientation contours can be provided for different workpieces. Accordingly, the design of the airflow channel can also be adapted to the respective workpiece.

[0041] According to a further aspect, the present disclosure relates to a machine tool comprising a frame, at least one workpiece table for receiving a workpiece holder, a clamping device according to at least one of the embodiments described herein, and at least one tool spindle that is movable in at least four or five axes relative to the workpiece support of the clamping device. This includes a relative movement between the tool spindle and the workpiece support, in which the tool spindle and / or the workpiece support can be actively moved.

[0042] In this way, highly complex contours can be machined. For example, the four axes of motion consist of three translational axes (X, Y, Z) and at least one or two swivel axes (e.g., A and / or C). The relative movement of the tool spindle with respect to the workpiece support can be generated, at least partially, by a movement of the workpiece support (relative to the tool spindle). The relative movement in four or five axes between the workpiece support and the tool spindle can be generated, at least partially, by an absolute movement of the tool spindle and, at least partially, by an absolute movement of the workpiece support. For example, translational axes are provided by movement of the tool spindle, and swivel axes by movement of the workpiece support.

[0043] According to another exemplary embodiment, the machine tool also features a measuring device with at least one probe designed to determine at least one rotational orientation of the rotational orientation contour or the clamped workpiece for the purpose of axis correction. For example, this involves the orientation of the workpiece around a so-called C-axis. The axis correction includes, for instance, a computational zero-point determination that allows for a highly accurate reference of the rotational orientation of the second side to the rotational orientation of the first side. The workpiece can be transferred without excessively high accuracy requirements. The alignment in the clamping device remains highly precise.

[0044] According to a further exemplary embodiment of the machine tool, the clamping device is a secondary clamping device for clamping the workpiece for machining a second side of the workpiece, wherein the machine tool can also be equipped with a primary clamping device for clamping the workpiece for machining a first side of the workpiece, and wherein the alignment of the workpiece in the second clamping device is carried out on the basis of an orientation section of the workpiece generated during the machining of the first side of the workpiece.

[0045] Suitable handling equipment is provided as needed for repositioning the workpiece. Gripping and repositioning the workpiece does not require the highest precision. It is generally conceivable to change the clamping devices themselves, so that one and the same machine tool can be used to machine both sides of the workpiece. It is also conceivable to use a machine tool with two or more spindles and two or more workpiece holders. This increases productivity. It is also generally conceivable to have both a primary clamping device for the first side and a secondary clamping device for the second side within a single machine tool.

[0046] According to another aspect, the present disclosure relates to a manufacturing plant for processing which has the following features: at least one machine tool with a frame, at least one workpiece table for receiving a workpiece holder and with at least one tool spindle, at least one primary clamping device mountable on the workpiece table for machining a first side of a workpiece, at least one clamping device designed according to at least one of the embodiments described herein and configured as a secondary clamping device mountable on the workpiece table for machining a second side of the workpiece, wherein the orientation section of the workpiece is created by machining the first side of the tool.

[0047] According to an exemplary embodiment, the manufacturing plant comprises a first machine tool, which carries the primary clamping device for machining the first side, and a second machine tool, which carries the secondary clamping device for machining the second side. Furthermore, the manufacturing plant may include suitable handling technology for transferring workpieces between the first and second machine tools.

[0048] According to another aspect, the present disclosure relates to a method for manufacturing a workpiece, comprising the following steps: Machining a first side of the workpiece with a machine tool, wherein the workpiece is clamped by a primary clamping device, providing a secondary clamping device designed according to at least one of the embodiments described herein, determining a rotational orientation of the rotational orientation contour of the secondary clamping device, in particular with a measuring probe, performing a computational axis correction based on the detected rotational orientation, and machining a second side of the workpiece, which is opposite the first side, with a machine tool, wherein the workpiece is clamped by the secondary clamping device.

[0049] The axis correction allows for highly precise machining of the second side relative to the previously machined first side. The rotational orientation for machining the second side can be determined by detecting the rotational orientation of the rotational orientation contour. This can be done by directly probing the rotational orientation contour (e.g., tactilely or optically) or indirectly probing it (by tactilely or optically probing a workpiece positioned within the rotational orientation contour). After the axis correction has been performed, further workpieces can be machined. The desired orientation is ensured by the rotational orientation contour and its known rotational orientation.

[0050] Further features and advantages will become apparent from the following description of several preferred embodiments with reference to the drawings. These show: Fig. 1: a perspective view of a machine tool; Fig. 2: a perspective view of a workpiece in the form of an impeller; Fig. 3: a schematic view of a first clamping device for machining a first side of the workpiece. Fig. 2 illustrated workpiece; Fig. 4: a schematic view of a second clamping device for machining a second side of the ... Fig. 2 illustrated workpiece; Fig. 5: a perspective view of the workpiece according to Fig. 2 in a different orientation; Fig. 6: a perspective view of a rotation direction contour for use with a clamping device for the workpiece according to Fig. 5 ; Fig. 7: a perspective view of the based on the Figuren 2 and 5 illustrate workpiece in a using the rotation orientation contour according to Fig. 6 achieved seat on a workpiece holder; Fig. 8: a perspective view of a further embodiment of a workpiece in the form of an impeller; Fig. 9: a perspective view of a rotation direction contour for use with a clamping device for the workpiece according to Fig. 8 ; Fig. 10: a perspective view of the based on the Fig. 8 illustrate workpiece in a using the rotation orientation contour according to Fig. 9 achieved fit on a workpiece holder; Fig. 11: Fig. 12: a schematic partial view of a machine tool with a first clamping device for machining a first side of a workpiece; Fig. 12: a schematic partial view of a machine tool with a second clamping device for machining a second side of the workpiece. Fig. 11 of the workpiece shown; Fig. 13: a schematic view of a production plant with two machine tools for manufacturing a workpiece by machining a first side and a second side; Fig. 14: a detailed view of one of the machine tools of the production plant according to Fig. 13 to illustrate a measuring process; Fig. 15: a perspective view of an embodiment of a rotation orientation contour with integrated channels for blown air; and Fig. 16: a simplified block diagram to illustrate an exemplary embodiment of a method for manufacturing a workpiece, comprising machining a first side and a second side opposite the first side.

[0051] Fig. 1 This illustrates the basic structure of a machine tool designated with the number 10, using a perspective view. Fig. 1 The machine tool 10 is designed as a so-called gantry machine. This is not to be understood as a limitation. Designs in portal construction (for example with a stationary portal), in moving column construction, or similar configurations are also conceivable.

[0052] In Fig. 1 For illustrative purposes, a Cartesian coordinate system XYZ is shown. This coordinate system serves to illustrate the basic orientations and axes of motion of the machine tool 10 and its components. An axis labeled X generally denotes a longitudinal extent. An axis labeled Y generally denotes a depth extent. In this embodiment, the X and Y axes together define a horizontal plane. An axis labeled Z generally denotes a vertical extent. The XYZ coordinate system primarily serves for illustrative purposes and is not to be understood as restrictive. It is understood that other coordinate systems can also be used to describe the machine tool 10 and its components. A person skilled in the art can perform the necessary transformations.

[0053] In the exemplary embodiment according to Fig. 1 The machine tool 10 has a frame 12, which can also be referred to as a base or bed. In the gantry machine configuration shown, the frame 12 comprises two side plates 14, on the upper surface of which guideways (Y-guideways) are formed. The machine tool 10 defines a work area 16 in which workpieces can be machined, in particular by machining. The work area 16 is usually enclosed (in a housing). Fig. 1 (not shown).

[0054] The machine tool 10 comprises a tool spindle 20 with a tool holder 22, which is designed to receive a tool 24. In the exemplary embodiment, the tool spindle 20 is oriented vertically. The tool spindle 20 is in Fig. 1 designed as a suspended spindle. Tools 24 can be driven around a vertically oriented spindle axis. The tool spindle 20 is movable relative to a workpiece support 26 in order to hold a workpiece (in Fig. 1 (not shown) to be machined. In the exemplary embodiment, the workpiece support 26 is arranged on a swivel bridge 28, which is supported on both sides by the cheeks 14 of the frame 12. Other configurations are conceivable. The tool spindle 20 is in Fig. 1 designed as a hanging vertical spindle.

[0055] The tool spindle 20 is movable in three linear axes relative to the workpiece support 26. For this purpose, an X-slide 30, a Y-slide 32, and a Z-slide 34 are provided in the exemplary embodiment. The Y-slide 32 is mounted on the sides 14 of the frame 12. The X-slide 30 is arranged to be linearly movable on the Y-slide 32. The Z-slide 34 is arranged to be linearly movable on the X-slide 30. The Z-slide carries the tool spindle 20. The X-slide 30 carries the Z-slide 34. The Y-slide 32 carries the X-slide 30.

[0056] The X-slide 30 is translationally movable along the Y-slide 32 in an X-axis 40 (X-direction). The Y-slide 32 is translationally movable along the Y-axis 42 (Y-direction) along the sides 14 of the frame 12. The Z-slide 34 is translationally movable along the Z-axis 44 (Z-direction) along the X-slide 30. The Z-slide 34 is vertically movable. The X-slide 30 and the Y-slide 32 are horizontally movable. In the exemplary embodiment, the swivel bridge 28 (A-axis 50, compare swivel movements about the X-axis) and the workpiece support 26 (C-axis 56, compare swivel movements about the Z-axis) provide further (rotational) axes of movement. Overall, 5-axis machining is possible with the machine tool 10. Other designs of machine tool 10 are conceivable, for example with a 4-axis kinematics, a 3-axis kinematics or the like.

[0057] The movement along the X, Y, Z axes can be effected by the spindle 22 or the workpiece support 26. It is essential that a relative movement occurs between the spindle 22 and the workpiece support 26. It is also conceivable that the movement along the Y-axis (arrow 42) is achieved, for example, by moving the workpiece support 26 along the frame 12.

[0058] Fig. 2 Illustrated by means of a perspective view of the design of a machined workpiece 60. For the design of workpiece 60, see also the Figuren 3-5 The workpiece 60 is, for example, an impeller 62. The workpiece 60 can also be referred to as a compressor wheel or the like. The workpiece 60 comprises a first side 66 and a second side 68 facing away from it. The first side 66 can also be referred to as the front. The second side 68 can also be referred to as the back. The terms first side, second side, front, and back are not to be understood as restrictive but rather serve for illustrative purposes. The different designations of the sides 66 and 68 refer in particular to the sequence of machining. In the exemplary embodiment, a circumferential wall 70 extends between the two sides 66 and 68, separating them from each other. The circumferential wall 70 is, for example, disc-shaped or disk-shaped; this is not to be understood as a limitation.

[0059] At its center, the workpiece 60 has a hub 72 through which a longitudinal axis 74 extends. During operation of the workpiece 60, the longitudinal axis 74 serves as the axis of rotation. A centering recess 76 extends along the longitudinal axis 74. In the exemplary embodiment, the centering recess 76 is designed as a through-hole / through-bore, see Figure 74. Fig. 3 und Fig. 4 The hub 72 has a front face 80 on the first side 66, see also Fig. 5 The hub 72 has a face 82 on its second side 68. The face 80 and the face 82 can be used for the axial alignment of the workpiece 60.

[0060] In the exemplary embodiment, the workpiece 60 carries on its first side 66 blades 86 of a first type and blades 88 of a second type. The blades 86, 88 are arranged distributed around the longitudinal axis 74. Several of the blades 86, 88 are provided, alternating between them.

[0061] Near their ends furthest from the second side 68, the blades 86 each form an orientation section 92 for the rotational orientation of the workpiece 60. The orientation section 92 includes an edge 94 at a frontal end of the blades 86. The edge 94 serves as a stop for the rotational alignment of the workpiece 60. The orientation section 92 of the blades 86 further includes a support area 96, which is spaced apart from the edge 94 and formed on a surface of the blades 86 furthest from the second side 68. The support area 96 simplifies the desired alignment of the workpiece 60.

[0062] The orientation section 92 (comprising, for example, the edge 94 and the support area 96) is, in exemplary embodiments, a section of the blades 86 that is already produced. On the opposite second side 68, blades 98 are formed, which are oriented in a specific rotational orientation relative to the blades 86, 88 on the first side 66. The blades 98 of the second side 68 are manufactured in a different setup than the blades 86, 88 of the first side 66. This will be explained below with reference to the Figuren 3-7 illustrated.

[0063] Fig. 3 Figure 1 illustrates a first clamping device 100 for machining the first side 66 of the workpiece 60 using a schematic diagram. The clamping device 100 is designed, for example, as a so-called swivel clamp 102. The clamping device 100 includes a hold-down device 104. In the exemplary embodiment, the hold-down device 104 is arranged on a boom 106 of the swivel clamp 102. The hold-down device 104 comprises a rotary bearing 108 and a pressure piece 110, which contacts the workpiece 60 on the first side 66 at the end face 80. The rotary bearing 108 decouples any rotational movement of the workpiece 60 from the first clamping device 100.

[0064] A double arrow labeled 114 illustrates in Fig. 3 the clamping or releasing movement of the swivel clamp 102. It is understood that the swivel clamp 102 may also be pivotable laterally to enable the handling (loading and unloading) of the workpiece 60.

[0065] The first clamping device 100 further comprises a workpiece holder 120, which, for example, is mounted on the rotatable workpiece table 26 of the machine tool 10 according to Fig. 1 is attached. The workpiece holder 120 comprises a workpiece support 122 that can be rotated about a longitudinal axis 124. When the workpiece 60 is clamped, the longitudinal axis 124 and the longitudinal axis 74 ( Fig. 2 The workpiece holder 120 also carries a centering mandrel 130, which extends into the centering recess 76 (also: center diameter) of the workpiece 60. The tip of the centering mandrel 130 faces the pressure piece 110 of the hold-down device 104. In this embodiment, the centering mandrel 130 centers the workpiece 60 in the centering recess 76 in a centering area 132 adjacent to the face 82. The workpiece 60 is thus centered close to the workpiece holder 120.

[0066] In Fig. 3 The workpiece 60 is additionally supported by a support surface 134 of the workpiece support 122, which is contacted by a corresponding support surface 136 adjacent to the circumference of the workpiece 60. In other words, the support surface 134 is significantly radially spaced from the longitudinal axis 124. The support surface 134 can be designed as an annular surface or as a segmented annular surface. The workpiece 60 is supported by its support surface 136 in an annular or segmental manner. The in Fig. 3 The design of the first clamping device 100 shown makes machining the workpiece 60 on the second side 68 difficult due to lack of accessibility. Depending on the design of the workpiece support 122, the second side 68 may not be accessible to a machining tool.

[0067] The workpiece 60 is located in Fig. 3 The clamping device 100 is axially clamped between the face 80 and the support surface 136 in the illustrated embodiment.

[0068] Fig. 4 Figure 1 illustrates another clamping device 150, which for illustrative purposes is referred to as the second clamping device 150. The clamping device 150 serves to hold the workpiece 60 in a clamping position in which the workpiece 60 can be machined on the second side 68. In this way, for example, blades 98 or similar contours can also be produced on the second side 68; compare Figure 1. Fig. 2 Wall 70 can also be edited.

[0069] The clamping device 150 is designed, for example, as a so-called swivel clamp 152. The clamping device 150 includes a hold-down device 154. In the exemplary embodiment, the hold-down device 154 is arranged on a boom 156 of the swivel clamp 152. The hold-down device 154 comprises a rotary bearing 158 and a pressure piece 160, which axially contacts the workpiece 60 on the second side 68 at the end face 82. The rotary bearing 158 decouples any rotational movement of the workpiece 60 from the first clamping device 150.

[0070] The workpiece 60 is held in the second clamping device 150 in a reversed orientation compared to the clamping device 100. In clamping device 150, the second side 68 faces the hold-down device 154. In clamping device 100, the first side 66 faces the hold-down device 104.

[0071] A double arrow labeled 164 illustrates in Fig. 4 the clamping or releasing movement of the swivel clamp 152. It is understood that the swivel clamp 152 may also be pivotable laterally to enable the loading and unloading of the workpiece 60.

[0072] The second clamping device 150 further comprises a workpiece holder 170, which, for example, can be mounted on the rotatable workpiece table 26 of the machine tool 10 according to Fig. 1 is attached. The workpiece holder 170 comprises a workpiece support 172 that can be rotated about a longitudinal axis 174. When the workpiece 60 is clamped, the longitudinal axis 174 and the longitudinal axis 74 ( Fig. 2 The workpiece holder 170 also carries a centering mandrel 180, which extends into the centering recess 76 (for example: center diameter) of the workpiece 60. The tip of the centering mandrel 180 faces the pressure piece 160 of the hold-down device 154. In the exemplary embodiment, the centering mandrel 180 centers the workpiece 60 in the centering recess 76 in a centering area 182 adjacent to the face 82. The workpiece 60 is thus centered close to the workpiece holder 170. In the illustrated exemplary embodiment, the hold-down device 154 with the pressure piece 160 is deliberately not used for centering.

[0073] In the exemplary embodiment, the centering mandrel 180 provides a contact surface 184 that contacts the face 80 of the hub 72 on the first side 66 of the workpiece 60. It is understood that the contact surface 184 can alternatively also be formed at the workpiece support 172. The workpiece 60 is in the Fig. 4 In the illustrated embodiment of the clamping device 150, the workpiece is clamped axially between the end face 82 and the end face 80. Likewise, the torque transmission occurs, at least essentially, between the support surface 184 and the end face 80 of the workpiece 60.

[0074] In exemplary embodiments, the contact surface 184 is provided with a friction-enhancing coating to increase the transmissible torque for a given axial force. This takes into account the fact that the contact surface 184 and the end face 80 facing it have a diameter that is small compared to the diameter of the workpiece 60, which results for force and torque transmission between the support surface 134 and the contact surface 136 (see Figure 1). Fig. 3 ).

[0075] When machining the second side 68 of the workpiece 60, precise rotational alignment between the contours of the first side 66 and the second side 68 is required. To facilitate alignment and avoid numerous individual measurements, the clamping device 150 has a rotational orientation contour 190 located between the workpiece support 172 and the workpiece 60. At least some of the blades 68 on the workpiece 60 itself have corresponding counter-contours that allow for precise rotational alignment of the workpiece 60 in the clamping device 150. The second side 68 is easily accessible for machining in the clamping device 150.

[0076] In the exemplary embodiment according to Fig. 4 The rotation orientation contour 190 is detachably attached to the workpiece support 172. A mounting plate 192 presses the rotation orientation contour 190 towards the workpiece support 172. This is done, for example, against a ring-shaped or disc-shaped base 194, without this being a limiting factor. Alternatively, the rotation orientation contour 190 can be screwed in place. In this way, the rotation orientation contour 190 can be quickly replaced in case of wear. This is advantageous, for instance, if the rotation orientation contour 190 is made of a relatively soft material to protect the workpiece 60. Furthermore, different rotation orientation contours 190 can be attached to the workpiece support 172 in this way to enable the machining of different workpieces.

[0077] Based on Fig. 4 illustrate the Figuren 5, 6 und 7 The interaction between the workpiece 60 and the rotational orientation contour 190 during the mounting of the workpiece 60 on the workpiece holder 170 of the clamping device 150 is shown using perspective representations.

[0078] Fig. 5 Figure 66 shows workpiece 60 in a perspective view from the first page 66; see also [reference to figure 66]. Fig. 2 with a representation from the second page 68. Fig. 6 Figure 1 illustrates an exemplary design of the rotation orientation contour 190. The rotation orientation contour 190 is designed as a crown 200 as an example. The rotation orientation contour 190 comprises a base 202, which is designed here in a ring shape. Rotation stops 204 extend from the base 202 and are formed on teeth 206. Fig. 7 Figure 1 shows a state in which the workpiece 60 is held on the workpiece holder 170 and its first side 66 contacts the rotation orientation contour 190. At least some of the edges 94 of the orientation sections 92 of the blades 86 of the workpiece 60 contact rotation stops 204 of the rotation orientation contour 190. In this way, a precise rotational alignment of the workpiece 60 about the longitudinal axis 74, 174 is achieved.

[0079] The rotation orientation contour 190 further features so-called support webs 210, which are arranged adjacent to at least some of the teeth 206 with rotation stop 204. The support webs 210 are designed to be flexible and are provided, for example, with a recess 212. The support webs 210 can deflect when the workpiece 60 with the blades 86 enters the rotation orientation contour 190. Fig. 7 This illustrates that the support webs 210 can each be contacted by a support area 96 of a blade 86 of the workpiece 60. The support area 96 faces away from the second side 68 and is inclined relative to the longitudinal axis 74, 174. In this way, when the workpiece 60 is axially pressed (compare the hold-down device 154 in Fig. 4 ) a rotary component that presses the edges 94 against the rotary stops 204 (in Fig. 7 counterclockwise).

[0080] To compensate for tolerances and ensure secure contact with the rotary stops 204, the support webs 210 are designed to be flexible in the exemplary embodiment. In this context, flexible means that the section modulus of the support webs 210 against deformation during contact by the blades 86 is lower to significantly lower than the section modulus of the teeth 206 with the rotary stops 204 during the same contact.

[0081] In Fig. 6 The space 216 indicates a gap in the crown 200 between a support bar 210 and a tooth 206 equipped with a rotation stop 204. A blade 86 of the workpiece 60 can engage in the space 216. In an exemplary embodiment, the crown 200 has a corresponding number of support bars 210, teeth 206, and the spaces 216 between them.

[0082] Fig. 6 Figure 1 illustrates a modified design in which the fixed sequence of teeth 206, gaps 216, and support ribs 210 is interrupted. A large / wide gap 218 is formed between two teeth 206, each of which is provided with a rotary stop 204. In this embodiment, the gap 218 is designed such that a measuring probe 224 can engage and contact a rotary stop 204. In this way, with a mounted rotary orientation contour 190, the given rotary orientation in the clamping device 150 can be determined. Since the workpiece 60 comes into contact with the rotary stops 204 at the edges 94 of the blades 86, this allows for highly precise rotary alignment between the first side 66 and the second side 68. It is understood that, if necessary, a measuring probe 224 can also engage in one of the gaps 216 and measure there, provided the width of the gap 216 permits this.

[0083] Fig. 7 shows the repeatable orientation of the workpiece 60 on the workpiece holder 170, whereby the rotational orientation is ensured by the rotational orientation contour 190.

[0084] The Figuren 8-10 This illustrates an alternative design of a workpiece designated 260. The following description explicitly refers to the preceding explanations in connection with the Figuren 2-7 .

[0085] Workpiece 260 is similar to workpiece 60 ( Fig. 2-7 ) designed as an impeller 262 or the like. The workpiece 260 comprises a first side 266 and a second side 268, which are machined in different clamping setups. Suitable clamping devices are the clamping device 100 ( Fig. 3 ) for the first page 266 and the clamping device 150 ( Fig. 4 ) for the second side 268. In the exemplary embodiment, a wall 270 is formed between the first side 266 and the second side 268, which separates the first side 266 and the second side 268 from each other.

[0086] The workpiece 260 comprises a hub 272 through which a longitudinal axis 274 extends. A centering recess 276 is arranged in the hub 272, which is concentric to the longitudinal axis 274. The hub 272 has an end face 280 on the first side 266 ( Fig. 8 ) and on the second page 268 a forehead 282 ( Fig. 10 ) on.

[0087] On the first side 266, the workpiece 260 has blades 286. When the workpiece is clamped in the clamping device 150 for machining the second side 268, the blades 286 serve to orient the workpiece 62 for rotation. For this purpose, the blades 286 have orientation sections 292. In the exemplary embodiment, these include edges 294 and support areas 296 spaced apart from them. The edges 294 are arranged at the ends of the blades 286 facing away from the second side 268. The support areas 296 are spaced apart from the edges 294 but adjacent to them. On the second side 268, blades 298 are formed which are oriented in a specific rotational orientation relative to the blades 286 on the first side 266.

[0088] Fig. 9 shows a perspective view of a rotation orientation contour 390, which is adapted to the design of the workpiece 260, in particular to the previously created design of the first side 266 with the blades 286. Fig. 10 Figure 1 shows the rotation orientation contour 390 in a state arranged in the workpiece holder 170 for receiving and rotating the workpiece 260. In the exemplary embodiment, the rotation orientation contour 390 is designed as a crown 400 and provided with an annular base 402. Several teeth 406 extend from the base 402, each carrying a rotation stop 404. The edges 294 of the blades 286 can contact the rotation stops 404. In this way, the workpiece 260 is aligned in the workpiece holder 170 with high precision and repeatability.

[0089] The rotational orientation contour 390 further features a plurality of support ribs 410, against which a support area 296 of the blades 286 can come into contact. The workpiece 260 can thus be aligned with high precision axially and with respect to its rotational orientation in the workpiece holder 170. When an axial force component is present, the contact of the support area 296 against the support rib 410 generates a resultant force that presses the edges 294 more strongly against the rotational stops 404 of the teeth 406 (in Fig. 10 (clockwise). Compared to teeth 406, the support bars 410 are designed to be more flexible, so that the support bars 410 can be moved as needed.

[0090] In Fig. 9 A gap between a rotary stop 404 and a support rib 410 is designated 416. A gap between a flank of the tooth 406 facing away from the rotary stop 404 and a subsequent support rib 410 is designated 418. Also in the Fig. 9 In the design of the rotation orientation contour 390 shown, the current rotation orientation can be determined by contacting the rotation orientation contour 390 itself or by contacting a captured workpiece 260 (for example, a reference part).

[0091] Fig. 11 The machining of the first side 66 of the workpiece 60 is illustrated using a schematic partial view of a machine tool 10. Fig. 12 Figure 1 illustrates the machining of the second side 68 of workpiece 60 using a schematic partial view. Machining of the first side 66 and the second side 68 can be performed in the same machine tool 10 if the tool is retooled accordingly. However, the machining can also be performed in different machine tools 10.

[0092] In Fig. 11 The workpiece 60 is secured to the workpiece table 26 of the swivel bridge 28 by the clamping device 100. The clamping device 100 allows machining of the first side 66, which is accessible to the tool 24 on the tool holder 22. The workpiece 60 is clamped axially between the hold-down device 104 and the support surface 134 of the workpiece support 122. Centering is achieved via the centering mandrel 130, which ensures concentric alignment with the longitudinal axis 124.

[0093] In Fig. 12 The workpiece 60 is secured to the workpiece table 26 of the swivel bridge 28 by the clamping device 150. The clamping device 150 allows the machining of the first side 68, which is for the tool 24 (in Fig. 12 (shown with dashed lines) is accessible. The workpiece 60 is clamped axially between the hold-down device 154 and the support surface 184 of the centering mandrel 180 or the workpiece support 172. Centering is achieved via the centering mandrel 180, which ensures concentric alignment with the longitudinal axis 174. Additionally, a rotation orientation contour 190 is provided, which ensures the desired rotational orientation of the workpiece 60.

[0094] In Fig. 12 Furthermore, a measuring probe 224 is schematically indicated, which in the exemplary embodiment is held on the tool holder 22. Accordingly, the measuring probe 224 can be moved with similar degrees of freedom as the tool 24. The measuring probe 224 is coupled to a measuring device 222 of the machine tool 10. The measuring device 222 is, for example, part of a higher-level control device of the machine tool 10. The measuring probe 224 can determine the current rotational orientation of the workpiece 60. This can be done by contacting the rotational orientation contour 190. However, contacting the workpiece 60 (reference part) is also conceivable. Based on the determined rotational orientation, an axis correction can be made, so that it is ensured that the second side 68 of the workpiece 60 is machined in the desired rotational orientation with respect to the first side 66.

[0095] Similarly, the Figuren 13 und 14 The machining of relevant workpieces 60 in a production plant designated 500 is shown using schematic views. In the exemplary embodiment, the production plant 500 has the following configuration: Fig. 13 Two machine tools 10 are linked together by appropriate handling technology 510. The machine tools 10 are exemplary analogous to the machine tool 10 according to Fig. 1 designed.

[0096] One of the two machine tools 10 carries a first clamping device 100 with a hold-down device 104 and a workpiece holder 120 for machining one side of the workpiece 60. The second machine tool 10 carries a second clamping device 150 with a hold-down device 154 and a workpiece holder 170 for machining a second side of the workpiece 60. The handling system 510 transfers the workpiece 60 between the two machine tools 10.

[0097] Fig. 14 Figure 1 illustrates a partial view of the machine tool 10 using a schematic diagram. The second clamping device 150 with the swivel clamp 152 is disengaged and swiveled away from the tool holder 170. Instead of a tool, the tool spindle 20 carries a touch probe 224 on its tool holder 22. The rotary orientation contour 190 is integrated into the tool holder 170. The touch probe 224 can probe the rotary orientation contour 190 to determine its rotational orientation. In this way, a plurality or multiple workpieces 60 can be clamped by the clamping device 150 using the rotary orientation contour 190 and machined with high accuracy with respect to their rotational orientation.

[0098] Fig. 15 A further design of a rotation orientation contour 190 is illustrated using a perspective view. Regarding the general design of the rotation orientation contour 190, reference is made to Fig. 6 und Fig. 7 taken. Additionally, shows Fig. 15 Flow channels 230 are integrated into the rotation orientation contour 190. The openings 232 of the flow channels 230 are each arranged in one of the gaps 216, 218. In the exemplary embodiment, the openings 232 are each adjacent to a rotation stop 204 of a corresponding tooth 206. In this way, a fluid (usually compressed air) can flow towards the blades arranged there (compare reference numeral 286 in Figure 1). Fig. 5 ) are blown to blow away chips and other contaminants from the workpiece 60 and the turning orientation contour 190.

[0099] The flow channels 230 can be integrated into the rotational orientation contour 190 or its crown shape. In this way, the flow channels 230 can be advantageously adapted to the respective workpiece 60. In the exemplary embodiment, the flow channels 230 are supplied via a central annular channel 234. The annular channel 234 is, for example, integrated into the base 204. However, the annular channel 204 can also be coupled to the rotational orientation contour 190 in another way.

[0100] Fig. 16This section illustrates an exemplary embodiment of a method for manufacturing a workpiece, particularly an impeller, compressor wheel, or the like, using a schematic block diagram. In this exemplary embodiment, the method begins with step S10. Step S10 comprises providing a first clamping device for machining a first side of the workpiece and clamping the workpiece into the first clamping device. The clamping device is provided, for example, in a first machine tool. In step S12, the first side of the workpiece is machined while clamped in the first clamping device.

[0101] Step S14 follows, which involves providing a second clamping device. The second clamping device can be provided in a second machine tool. However, it is also conceivable to provide both the first and second clamping devices in the same machine tool. Step S16 involves determining the current rotational orientation of the second clamping device or of a workpiece (reference part) held in it. A subsequent step S18 involves a computational axis correction to account for the given rotational orientation.

[0102] In the exemplary embodiment, one of the steps S14 or S16 includes clamping the workpiece in the second clamping device. The timing of the clamping process depends on whether the current rotational orientation is determined by (optical or tactical) probing of the rotational orientation contour or of the workpiece itself.

[0103] Step S20 follows, which involves machining the second side of the workpiece while it is clamped in the second clamping device. The second side is machined in a favorable and precise rotational orientation relative to the contours of the first side of the workpiece created in step S12. In principle, further workpieces can now be machined on both the first and second sides without having to repeat steps S16 and S18. The rotational orientation contour ensures that new workpieces are precisely and consistently aligned in the second clamping device for machining their second side. After axis correction, this orientation is stored in the machine tool's control system.

Claims

1. Clamping device (150) for receiving a workpiece (60, 260) to be machined by material removal, in particular for machining an impeller (62, 262) to be machined on both sides, comprising: - a workpiece holder (170) drivable rotatably about a longitudinal axis (174) and having a workpiece support (172), - a downholder (154) which, at least in a clamping position, faces the workpiece support (172) in order to clamp a workpiece (60, 260) that is provided with a centering recess (76, 276) concentrically with respect to the longitudinal axis (174) between the workpiece support (172) and the downholder (154), and - a rotational orientation contour (190, 390) which is arranged at the workpiece support (172) and provides at least one rotation stop (204, 404) for an orientation section (92, 292) of the workpiece (60, 260) for rotational alignment of the workpiece (60, 260) in the clamping position, characterized in that the rotational orientation contour (190, 390) comprises a crown (200, 400) surrounding the longitudinal axis (174), and that the at least one rotation stop (204, 404) is formed on a tooth (206, 406) of the crown (200, 400).

2. Clamping device (150) according to claim 1, wherein the rotational orientation contour (190, 390) comprises a plurality of rotation stops (204, 404) distributed about the longitudinal axis (174), and / or wherein the crown (200, 400) is removably fastened to the workpiece holder (170).

3. Clamping device (150) according to claim 1 or 2, wherein the crown (200, 400) comprises a plurality of teeth (206, 406) with rotation stops (204, 404) distributed about the longitudinal axis (174), and wherein a gap (218, 418) for a measuring probe (224) is formed between at least two teeth (206, 406).

4. Clamping device (150) according to any one of claims 1 to 3, wherein at least one tooth (206, 406) of the crown (200, 400) is adjacent to a support web (210, 410) that is particularly configured to be resilient, wherein a gap (216, 416) is formed between the rotation stop (204, 404) of the tooth (206, 406) and the support web (210, 410), into which, in the clamping position, a blade (86, 286) of the workpiece (60, 260) is inserted, wherein the blade (86, 286) contacts the rotation stop (204, 404) with an edge (94, 294), and wherein the support web (210, 410) is formed to support the blade (86, 286) at a support region (96, 296) spaced apart from the edge (94, 294).

5. Clamping device (150) according to any one of claims 1 to 4, wherein the rotational orientation contour (190, 390) is made of a plastic material or an aluminum-based material.

6. Clamping device (150) according to any one of claims 1 to 5, wherein the workpiece holder (170) carries a centering pin (180) which, in the clamping position, projects into the centering recess (76, 276) of the workpiece (60, 260).

7. Clamping device (150) according to claim 6, wherein the centering pin (180) centers the workpiece (60, 260) in a centering region (182) of the centering recess (76, 276), with the centering region (182) of the workpiece (60, 260) being adjacent to the workpiece support (172) in the clamping position, and / or wherein the centering pin (180) has an end face support surface (184) that is particularly provided with a friction-increasing coating, in particular a diamond coating.

8. Combination of a clamping device (150) according to any one of claims 1 to 7 and a workpiece (60, 260) received thereon for machining purposes.

9. Combination according to claim 8, wherein the at least one rotation stop (204, 404) for rotational alignment of the workpiece (60, 260) is adapted to a blade (86, 286) of the workpiece (60, 260), and wherein in particular the at least one rotation stop (204, 404) is adapted to an edge (94, 294) of the blade (86, 286).

10. Combination according to claim 8 or 9, wherein the at least one rotation stop (204, 404) is adapted to an orientation section (92, 292) of the workpiece (60, 260) produced in another clamping operation.

11. Combination according to any one of claims 8 to 10, wherein the downholder (154) acts axially on a hub (72, 272) of the workpiece (60, 260) in the clamping position, in particular on an end face (82, 282) of the hub (72, 272), and / or wherein at least one flow channel (230) for blow-off air is formed in the rotational orientation contour (190, 390), and preferably a plurality of outlets (232) are provided which, in the clamping position, are directed toward the workpiece (60, 260).

12. Machine tool (10) comprising a frame (12), at least one workpiece table (26) for receiving a workpiece holder (170), a clamping device (150) according to any one of claims 1 to 7, at least one tool spindle (20) movable in at least four or five axes relative to the workpiece support (172) of the clamping device (150), and preferably a measuring device (222) with at least one measuring probe (224) configured to determine, for axis correction purposes, at least one rotational orientation of the rotational orientation contour (190, 390) or of the clamped workpiece (60, 260).

13. Machine tool (10) according to claim 12, wherein the clamping device (150) is a secondary clamping device (150) for clamping the workpiece (60, 260) for machining a second side (68, 268) of the workpiece (60, 260), wherein the machine tool (10) is further equipable with a primary clamping device (100) for clamping the workpiece (60, 260) for machining a first side (66, 266) of the workpiece (60, 260), and wherein the alignment of the workpiece (60, 260) in the secondary clamping device (150) is based on an orientation section (92, 292) of the workpiece (60, 260) produced during machining of the first side (66, 266).

14. Manufacturing system (500) for machining, comprising: - at least one machine tool (10) having a frame (12), at least one workpiece table (26) for receiving a workpiece holder (170), and at least one tool spindle (20), - at least one primary clamping device (100) mountable on the workpiece table (26) for machining a first side (66, 266) of a workpiece (60, 260), - at least one clamping device (150) according to any one of claims 1 to 7, configured as a secondary clamping device (150) mountable on the workpiece table (26) for machining a second side (68, 268) of the workpiece (60, 260), wherein the orientation section (92, 292) of the workpiece (60, 260) is produced by machining the first side (66, 266) of the workpiece (60, 260).

15. Method for manufacturing a workpiece (60, 260), comprising the steps of: - machining a first side (66, 266) of the workpiece (60, 260) with a machine tool (10), the workpiece (60, 260) being clamped by a primary clamping device (100), - providing a secondary clamping device (150) configured according to any one of claims 1 to 7, - determining a rotational orientation of the rotational orientation contour (190, 390) of the secondary clamping device (150), in particular with a measuring probe (224), - performing a computational axis correction based on the detected rotational orientation, and - machining a second side (68, 268) of the workpiece (60, 260) opposite the first side (66, 266) with a machine tool (10), with the workpiece (60, 260) being clamped by the secondary clamping device (150).