DE102018130680A1 - Center support and spindle unit - Google Patents

Abstract

The invention relates to a center support (2) for supporting and / or clamping a workpiece to be machined, a spindle unit (83) and a processing device (80) with a center support (2) and / or a spindle unit (83), the center support (2 ) has: a chuck (4) rotatably mounted about an axis (M) with a set of clamping segments (8a-c) for clamping a workpiece on a peripheral area, a hollow spindle shaft (18) in which the clamping segment set (8a-c) is arranged , wherein the spindle shaft (18) is rotatably mounted on two axially spaced bearings (38a-b) in the center support (2); and an actuating device for actuating the clamping segment set (8a-c), the actuating device having at least one spring element (20) which, due to its preload, closes the clamping segment set (8a-c) for clamping a workpiece, the actuating device comprising a set of clamping wedges (12a-12) c), and a clamping wedge (12a-c) is arranged between each clamping segment (8a-c) and the spindle shaft (18), each clamping wedge (12a-c) having a first wedge surface (14a-c) and the associated clamping segment (8a-c) has a second wedge surface (16a-c) resting on the first wedge surface (14a-c), and wherein the first and second wedge surfaces (14a-c, 16a-c) are flat and / or are plane-parallel.

Description

The invention relates to a center support and a spindle unit for a processing device for processing workpieces, and a processing device with such a center support and / or spindle unit.

For safe machining of long workpieces or for end machining, steadies or setting sticks are used, which support or hold the workpiece to be machined in the center or at a distance from the workpiece ends. A center drive machine is known for example from the EP 1 510 275 B1 .

It is an object of the invention to provide an improved center support and spindle unit for a processing device, a processing device with such a center support and / or such a spindle unit, and a method for a processing device, which enable precise fixing for precise machining of a workpiece .

This object is achieved with the features of claims 1, 9, 14 and 15, respectively.

Advantageous refinements are the subject of the dependent claims.

According to claim 1, a center support for supporting and / or clamping a workpiece to be machined is provided. The center support has a chuck rotatably mounted about the axis of rotation of the center support with a set of clamping segments for clamping a workpiece on a peripheral region. For clamping or releasing a workpiece, the clamping segments can be fed radially to a workpiece or removed radially from a workpiece. The clamping segment set is arranged in a hollow spindle shaft (hollow shaft) of the chuck. The spindle shaft is rotatably mounted in the center support on two axially spaced apart bearings. Preferably the center support or chuck is not driven, i.e. the chuck is moved passively. If, for example, a workpiece end is clamped and rotated in a driven main spindle of a processing device, the shaft of the center support (in which the workpiece is additionally clamped) is driven around the axis of rotation of the center support.

An automatic actuating device is designed to actuate the clamping segment set for clamping or releasing a workpiece in the chuck. For this purpose, the actuating device has at least one spring element which, due to its pretension, closes the clamping segment set for clamping a workpiece. For example, compression springs or alternatively disc springs can be used. In particular, by using spring elements with suitable spring strengths, the clamping force of the actuating device acting on a workpiece can be set or changed simply and inexpensively.

The actuating device furthermore has a set of clamping wedges, one clamping wedge each being arranged between the spindle shaft and each clamping segment. Each clamping wedge has a first wedge surface and the associated clamping segment has a second wedge surface resting on the first wedge surface. Moving the two wedge surfaces against each other causes a uniform radial stroke or a radial movement of the clamping segments for clamping or releasing a workpiece to be machined. Preferably, as described below, the radial movement of the clamping segments is brought about by the axial displacement of the clamping wedges, i.e. the clamping segments are not axially displaced or the clamping segments are fixed in the axial direction in the center support. The (axial) movement of the clamping wedges in the direction of their wedge tip causes a radial movement (clamping stroke) of the clamping segments to the axis of the center support, so that a workpiece is clamped by the clamping segment set. Conversely, the (axial) movement of the clamping wedges in the opposite direction to the wedge tip preferably causes a radial movement of the clamping segments away from the axis of the center support, so that a workpiece clamped in the clamping segment set is released.

The first wedge surface and the second wedge surface are advantageously designed to be plane and / or are plane-parallel. If the wedge surfaces are flat or the wedge surfaces have no curvature, twisting of the clamping segments against the clamping wedges (around the axis of rotation of the center support) is prevented. I.e. The planarity of the wedge surfaces ensures the position of the wedge surfaces with respect to one another and ensures that the first and second wedge surfaces are in full contact with one another at all times and thus the (radial) clamping forces are always distributed uniformly over the entire surface of the first / second wedge surfaces. The clamping forces are thus safely transmitted via the flat (wedge) surfaces from the clamping segments via the clamping wedges to the inner surface of the hollow spindle shaft, whereby a clamped workpiece can be securely fixed in the center support and machined precisely.

The (first and second) wedge angles are inclined at an angle to the axis of rotation of the center support. Preferred meadow, the wedge surfaces to the axis of the center support at an angle between 4 ° and 20 °, preferably one Angles between 5 ° to 8 °, 8 ° to 10 °, 10 ° to 12 °, 12 ° to 15 °, or 15 ° to 20 °. As described above, the clamping segments are moved radially by the two wedge surfaces and the axial movement of the clamping wedges (clamping stroke). The clamping stroke, ie the radial (clamping) movement of the clamping segments, can be set using the wedge angle. For example, with a wedge angle of 5 ° - with the same axial movement of the clamping wedges - the clamping stroke is less than with a wedge angle of 15 °, for example.

The center support or the actuating device preferably has a tensioning cylinder, the tensioning wedges being arranged on the tensioning cylinder, in particular being formed in one piece with the tensioning cylinder. The clamping cylinder can be arranged between the spindle shaft and clamping segments, so that the clamping wedges are located between the spindle shaft and the clamping segments as described above. For example, the clamping wedges are arranged on a revolving clamping cylinder, the clamping wedges projecting axially (parallel to the axis of the center support) from the clamping cylinder. The tensioning cylinder connects all the tensioning wedges and is in particular formed in one piece with the tensioning wedges, so that the center support has fewer individual parts and thus maintenance / handling is made easier.

The clamping cylinder is particularly preferably designed such that the clamping wedges are flexible or slightly elastic radially to the (rotary) axis of the center support. This ensures that when clamping a workpiece, the clamping wedges lie or lie against the entire surface of the inside of the spindle shaft, in particular lie flat. In particular, the clamping wedges are flexible in the radial direction, so that when a workpiece is clamped, the first wedge surface lies flat on the second wedge surface. Radial inaccuracies can be compensated for by means of the flexible clamping wedges, so that optimal power transmission between the clamping segments and the spindle shaft is always guaranteed. The spindle shaft is preferably made of a highly wear-resistant material, in particular highly wear-resistant against adhesive wear.

The automatic actuating device is preferably designed to move the clamping wedges and / or the clamping cylinder in the axial direction into a closed position, so that the clamping segment set closes for clamping a workpiece. In particular, the automatic actuating device is designed to move the first wedge surface against the second wedge surface, so that the clamping segment set closes for clamping a workpiece.

To release the clamping segments or the chuck, the center support can have an actuator which acts on the at least one spring element. The actuator is slidably mounted in the center support, in particular in a non-rotatable / fixed housing of the center support. The actuator can preferably be actuated hydraulically. For example, the actuator has an annular piston, the actuator actuating the annular piston to actuate the clamping wedges or the clamping cylinder in an open position against the pretensioning of the at least one spring element, so that the clamping segment set (for releasing a workpiece) opens. In particular, the actuator has a disk-shaped ring piston. Due to the small axial expansion of an annular piston, the axial expansion or height of the center support is also kept small. When the actuator is actuated hydraulically, pressures between 80 bar and 200 bar can be used, correspondingly adapted to the spring forces of the spring elements of the actuating device used. The actuator preferably acts on the clamping segment set via the clamping cylinder. If e.g. If the clamping cylinder or the clamping wedges are moved axially against the spring force by the actuator against the direction of the wedge tips of the clamping wedges, the clamping segments detach from the clamped workpiece, so that the workpiece can be removed from the center support.

According to one embodiment, the center support in the area of the (internal) clamping segment set is designed to spring back axially, or the central support has a smaller axial extent in the area of the (internal) clamping segment set than in the area of the (external) spindle shaft and the clamping cylinder. The recessed clamping segment set forms a central recess in the center support, which is preferably designed so that a chuck of a main spindle - in which a workpiece to be machined is clamped - can be moved as close as possible to the clamping segment set or can be immersed in the recess. This means that even very short workpieces can be held in the center support, e.g. for end processing. For example, the center support (with housing) has an axial extent between 80 mm to 120 mm, particularly preferably from or about 100 mm, and / or the center support has an axial extent between 20 mm to 60 mm in the (central) region of the clamping segments , preferably of or of about 45 mm.

Each clamping segment preferably has (rear) lateral guides, guide grooves or cutouts in order to accommodate the associated clamping wedges. The recess is designed to guide and stabilize the clamping wedge laterally or in the direction of rotation of the chuck. The (second) lies in the recess or guide groove Wedge surface of the clamping segment, which interacts with the (first) wedge surface of the clamping wedge. The position of the two wedge surfaces relative to one another is secured against displacement by the guide groove. In addition, the correct positioning of the clamping wedges and clamping segments relative to one another in the center support is simplified during assembly / installation.

In one embodiment, the clamping segment set is exchangeable and / or removable. By using the clamping wedges or wedge surfaces, the maximum possible clamping stroke of the clamping segments in the radial direction is very limited. Therefore, clamping segments adapted to different diameters (cross sections) of a workpiece to be machined with appropriately designed clamping surfaces are used in the center support.

According to a preferred embodiment, a clamping segment is formed from a clamping slide and an interchangeable jaw which is detachably connected to the clamping slide, the second wedge surface being formed on the back of the clamping slide and a clamping surface for contacting the peripheral region of a workpiece to be machined. I.e. in order to machine different workpieces, only the interchangeable jaw has to be exchanged. In particular, it is not necessary to separate the first / second wedge surfaces from one another for changing the clamping segments / the interchangeable jaw, so that contamination of the first / second wedge surfaces is prevented.

According to one embodiment, a processing device with a center support as described above is provided. For example, a processing machine with a (horizontally or vertically aligned) skin spindle for clamping a workpiece and a tool that can be advanced to the workpiece, such as milling, drilling, turning and / or grinding tools, e.g. provided by means of a tool turret.

The use of the center support described above with a processing device is described below by way of example. The center support is advantageously mounted on a machine base of the processing device (e.g. axially movable). A workpiece to be machined can be held in a clamping and drive unit (main spindle) of the machining device. The drive axis of the main spindle or the axis of the center support can run horizontally or preferably vertically. The center clamping is carried out on a high-precision machined fit (circumferential flat surface), which on the workpiece to be machined before clamping in the center support - e.g. with a grinding machine - was produced or ground. This circumferential plane surface serves as a reference surface for the subsequent processing in the processing device. When producing the circumferential plane surface, the workpiece is clamped and centered in the center holes at the workpiece ends. Subsequently, the prepared workpiece is also aligned via the same center holes in the quill of the machining device to maintain dimensional accuracy. This ensures that the workpiece or the circumferential plane surface is precisely positioned in the center support and that the workpiece can subsequently be machined with high precision.

For example, to insert or position the workpiece in the machining device, the center support can be moved axially along a linear guide, so that the center support does not hinder the insertion of the workpiece. To insert a workpiece, the center support or the clamping segment set is in the open position, i.e. the hydraulically actuated actuator opens the tensioning segments against the pretensioning of the spring elements of the actuating device. After the workpiece has been inserted and positioned, the actuator or the annular piston is released, so that the actuating device uses the spring elements to move the clamping segment set into a closed position for clamping the workpiece on the circumferential plane surface. The workpiece can then be driven by means of the main spindle and machined by means of adjustable tools of the processing device.

According to another aspect disclosed here, a spindle unit is provided for a machining device, in particular for a workpiece machining device as described above. The spindle unit has a main spindle shaft rotatably mounted in a housing and a motor drive connected to the main spindle shaft for driving the main spindle shaft about a drive axis. A clamping device with a chuck for clamping a workpiece is arranged on the main spindle shaft. A workpiece can be clamped with the spindle unit and e.g. fixed for milling and drilling work or driven in rotation for turning work. Unless otherwise stated, the terms "axial" and "radial" refer to the drive axis of the spindle unit.

A stop spindle device is mounted coaxially in the (hollow) main spindle shaft. The stop spindle device has a stop spindle and a stop tip. A spindle drive is connected to the stop spindle device in order to move the stop spindle device axially (along the drive axis). For example, an NC or CNC spindle drive is used. Through the axial movement of the NC stop spindle device the NC stop tip can be moved to a desired target position or a target position can be approached exactly. The target position of the stop tip in turn defines the position of a workpiece or workpiece end to be machined, which is placed or abuts the stop tip. In other words, the axially movable stop spindle device allows the (axial) position of a workpiece to be machined to be precisely defined in a machining device, in particular both before and after the workpiece is clamped in the clamping device or the chuck of the spindle unit.

With the spindle unit described, a workpiece can - in addition to clamping and rotating driving - be positioned exactly axially. Preferably, a workpiece also lies in the clamping device after clamping, i.e. during workpiece machining, on the stop spindle device or the stop tip, so that the (axial) position of the workpiece is or remains secured even during workpiece machining.

The dimensional accuracy of the subsequent workpiece machining is significantly increased by the precise positioning by means of the stop spindle device. For example, in the case of a machining device, a tailstock opposite the stop spindle device or a quill with a centering tip can be provided, so that after the stop spindle device has been positioned, a workpiece can be held on the stop tip of the stop spindle device by means of the tailstock or clamped between the stop tip and tailstock. For positioning, a workpiece preferably has a centering hole at its ends to be clamped in, for receiving the stop tip or a centering tip of the tailstock.

Preferably, at least the stop spindle is decoupled from the motor drive in the main spindle shaft, so that at least the stop spindle is mounted in the main spindle shaft without rotation. In particular, at least the stop spindle can only be moved axially or is non-rotating in the main spindle shaft. I.e. at least the stop spindle is fixed in the main spindle (in the direction of rotation of the drive axis). Since the stop spindle is decoupled from the motor drive and from the radial forces occurring during rotation, the stop spindle device can be aligned or positioned even more precisely axially. If the workpiece is to be rotated, the stop spindle device has, for example, a rotatingly mounted tip (as with a sleeve or as described below) and / or the stop spindle unit is withdrawn from the workpiece after it has been clamped, so that there is no longer any contact with the workpiece given is.

The spindle unit preferably has a guide housing in which the stop spindle device is mounted so that it can move axially, the guide housing being connected to the main spindle shaft and / or the clamping device in a rotationally fixed manner. I.e. the guide housing, e.g. a guide tube rotates with the main spindle shaft and is connected to the chuck, for example, via a spindle flange with the main spindle shaft and via a chuck flange. At least the stop spindle can be moved axially in the guide housing without rotation as described above.

The stop spindle device preferably has a hollow quill which is axially displaceably mounted in the guide housing, the quill being rotatably mounted on the (fixed) stop spindle on at least two axially spaced apart bearings. The stop tip is preferably connected to the hollow quill in a rotationally fixed manner and protrudes from the hollow quill in the direction of the chuck / a chuck receiving opening of the spindle shaft. In particular, the hollow sleeve and the guide housing are connected to one another in a rotationally fixed manner. I.e. the stop tip rotates with the hollow sleeve, guide housing and main spindle shaft, while the stop spindle is fixed. The main spindle shaft, guide housing, hollow quill, stop spindle and stop tip are arranged coaxially with each other. Since the stop tip is coupled to the motor drive of the spindle unit, the stop tip can remain attached to the end of the workpiece even during workpiece machining and thus secure the position of the workpiece even during machining.

According to one embodiment, the spindle unit has a referencing device with a referencing surface formed on the hollow sleeve and an axially spaced referencing stop formed on the guide housing. During the operation of the spindle unit, (axial) changes in length of the stop spindle device or the stop spindle can occur, e.g. by warming. A reference run can be carried out to compensate for these changes. The stop spindle device or the hollow sleeve is moved axially to the zero position, i.e. until the homing surface rests on the homing stop so that the axis is "zeroed".

The guide housing is preferably mounted in a clamping housing of the chuck device, the clamping housing being axially operable for clamping a workpiece and connected to the main spindle shaft in a rotationally fixed manner. Ie the guide housing and the clamping housing are coaxial aligned and coupled to the main spindle shaft, the clamping housing being axially movable / actuatable and the guide housing being axially “fixed” or fixed. This ensures a constant axial position of the guide housing in the spindle unit, which ensures exact axial positioning of the stop tip.

The spindle drive preferably has an NC motor and / or the spindle drive has a ball screw drive. For example, the stop spindle is designed as a ball screw which can be driven via a corresponding spindle nut driven by the motor. Ball screws have high positioning accuracy and low wear.

In one embodiment, the stop spindle device has a torque support device for supporting at least the stop spindle against (axial) torques, the torque support device having a torque support connected to the stop spindle device (non-rotatably) with at least one support roller and a support housing connected to the main spindle housing with a support roller guide for the at least one support roller having. When the stop spindle is moved axially, the at least one support roller is also moved axially in its guide, so that the guide running parallel to the working axis of the main spindle prevents the stop spindle from rotating or rotating. The torque support preferably has at least two axially opposite support rollers, in particular two support rollers offset by 180 °, and correspondingly two opposite support roller guides on the support housing.

According to one aspect disclosed here, a processing device with a base body and a spindle unit mounted on the base body with a stop spindle device as described above is provided. Preferably, the machining device additionally has a tailstock mounted on the base body and opposite the spindle unit, a workpiece being clampable between the stop spindle device and the tailstock. For example, a tailstock can have a quill with a centering tip.

The tailstock is preferably axially movable. After positioning the stop tip, a workpiece can be clamped between the stop tip and the tailstock by moving the tailstock. In addition, after clamping a workpiece in the clamping device of the spindle unit, the tailstock can be removed from the workpiece end, e.g. for finishing the workpiece.

The machining device disclosed herein preferably sees a vertical alignment of the axis of rotation of the workpiece or the drive spindle unit (main spindle unit). In an embodiment, the axis of rotation can also be aligned horizontally or inclined. The machining device may include elements of the stop spindle device and / or the center support described in any combination, partial combination or sub-combination as disclosed above or in the following detailed description.

According to a further embodiment, a processing device is provided with a base body, a spindle unit mounted on the base body with a stop spindle device as described above, a center support mounted on the base body as described above, and a tailstock mounted on the base body opposite the spindle unit, in particular movable tailstock mounted on the base body.

A preferred embodiment of a method for clamping and machining a workpiece in a machining device is described below, the machining device comprising: a base body; a spindle unit mounted on the base body with a stop spindle device as described above; a tailstock mounted axially opposite the spindle unit on the base body; a center support between the spindle unit and tailstock on the base body as described above.
The method preferably has: moving the one stop tip of the stop spindle device along a drive axis of the spindle unit into an axial desired position; Inserting a workpiece between the tailstock and the stop tip of the stop spindle device; Clamping the workpiece by moving the tailstock axially; Clamping the workpiece in the center support; Clamping a workpiece end in a chuck of the spindle unit, in particular removing the tailstock from the workpiece by axial movement; and machining the workpiece.

According to this method, a workpiece is brought into a desired axial position in a first step - by placing the workpiece on the stop tip in the desired position - and then clamped in the center support and only then clamped in the chuck of the spindle unit.

The desired position of the stop spindle device or stop tip is preferably determined by a predetermined (axial) clamping position of the center support. The predetermined clamping position of the center support on the base body is determined by the position of one on machining workpiece arranged reference surface or circumferential plane surface. If the (for example axially movable) center support on the base body is in the clamping position, the center support clamps the workpiece on the reference surface or the clamping segments of the center support rest on the reference surface. The clamping position of the center support preferably coincides with the reference surface on the workpiece, ie the target position of the stop tip is determined by the axial position of a reference surface on a workpiece to be machined. Moving the stop tip into the desired position (and placing the workpiece against the stop tip) ensures that a workpiece is always held on its reference surface or circumferential plane surface by the center support.

The method preferably has the step of generating a reference surface (circumferential plane surface / fit) on the workpiece before inserting a workpiece, e.g. by means of grinding. As described above, the center support clamps the workpiece on the reference surface. Since a workpiece is clamped on a precisely machined reference surface by the center support, the subsequent machining can be carried out with high dimensional accuracy. In particular, the reference surface forms the reference surface for all subsequent workpiece machining operations in the machining device.

When generating the reference surface, the workpiece is particularly preferably fixed at its ends via center holes, e.g. in a grinding machine, the positioning tip and clamping of a workpiece in the (subsequent) machining device engaging the stop tip and the tailstock in the centering holes. I.e. the clamping position of the workpiece when generating the reference surface can be exactly reproduced in the subsequent machining. The workpiece or the reference surface is precisely aligned in the machining device using the centering holes and clamped for high-precision workpiece machining.

In one embodiment, the center support is axially displaceably mounted on the base body, the method comprising the further steps: before inserting the workpiece, moving the center support to the tailstock so that a centering tip of the tailstock protrudes at least partially through the center support, and after clamping one Workpiece between tailstock and stop spindle device, method of center support to one or the clamping position and / or to one or the reference surface on the workpiece, and clamping the workpiece in the center support. This configuration ensures that the center support is out of the way during the clamping of a workpiece or does not hinder the clamping, in particular with longer workpieces.

The elements of the stop spindle device and / or the center support described here can be combined with one another in any combination, partial combination or sub-combination and can define the subject matter of a claim. The combination, partial or sub-combination may result from elements as disclosed above or in the detailed description.

• 1a-c eine Perspektivansicht, eine Seitenansicht und eine Draufsicht einer Mittenabstützung gemäß einer bevorzugten Ausgestaltung,
• 2a-d geschnittene Teilansichten der Mittenabstützung von 1a-c in Klemmstellung (2a, 2b) und Offenstellung (2c, 2d),
• 3a-b eine Draufsicht und einen Querschnitt eines Teils der Mittabstützung von 1a-c,
• 4a-b Perspektivansichten eines Spannzylinders und einer Spindelwelle der Mittabstützung von 1a-c,
• 5 Perspektivansichten des Spannzylinders und der Spannsegmente im montierten und demontierten Zustand,
• 6a-f zeigen verschiedene Ansichten eines zweiteiligen Spannsegments für die Mittenabstützung von 1a-c im zusammengebauten Zustand,
• 7a-g zeigen verschiedene Ansichten des zweiteiligen Spannsegments von 6a-f teilweise demontiert,
• 8 eine Perspektivansicht einer beispielhaften Bearbeitungseinrichtung mit der Mittenabstützung von 1a-c,
• 9a-b Perspektivansichten einer Spindeleinheit mit einer Anschlagspindeleinrichtung gemäß einer bevorzugten Ausgestaltung,
• 10a-c eine Seitenansicht, eine geschnittene Vorderansicht und eine geschnittene Draufsicht eines Teils der Spindeleinheit von 9a-b,
• 11a-b Perspektivansichten der Anschlagspindeleinheit von 9a-b,
• 12a-d eine Ansicht von unten, sowie Schnittansichten und eine Detailansicht im unteren Bereich der Spindeleinheit von 9a-b,
• 13a-b eine Perspektivansicht und eine Schnittansicht eines Teils einer Spanneinrichtung der Spindeleinheit von 9a-b, und
• 14a-b eine Perspektivansicht und eine Schnittansicht eines Teils der Anschlagspindeleinrichtung von 9a-b, die in dem Teil der Spanneinrichtung von 13a-b angeordnet ist.

Embodiments of the invention are explained in more detail with reference to figures. Show it:

• 1a-c 2 shows a perspective view, a side view and a top view of a center support according to a preferred embodiment,
• 2a-d sectional partial views of the center support of 1a-c in clamping position ( 2a , 2 B) and open position ( 2c , 2d ),
• 3a-b a plan view and a cross section of part of the center support of 1a-c ,
• 4a-b Perspective views of a clamping cylinder and a spindle shaft of the center support from 1a-c ,
• 5 Perspective views of the clamping cylinder and the clamping segments in the assembled and disassembled state,
• 6a-f show different views of a two-part clamping segment for the center support of 1a-c when assembled,
• 7a-g show different views of the two-part clamping segment of 6a-f partially dismantled,
• 8th a perspective view of an exemplary processing device with the center support of 1a-c ,
• 9a-b Perspective views of a spindle unit with a stop spindle device according to a preferred embodiment,
• 10a-c a side view, a sectional front view and a sectional plan view of a part of the spindle unit of FIG 9a-b ,
• 11a-b Perspective views of the stop spindle unit from 9a-b ,
• 12a-d a view from below, and sectional views and a detailed view in the lower region of the spindle unit of 9a-b ,
• 13a-b a perspective view and a sectional view of part of a clamping device of the spindle unit of 9a-b , and
• 14a-b a perspective view and a sectional view of part of the stop spindle device of 9a-b that in the part of the tensioner of 13a-b is arranged.

Below is a preferred embodiment of a center support 2nd described for clamping or supporting a workpiece. One with the center support 2nd The held workpiece can be processed using milling, turning, drilling and / or grinding tools, for example for the production of engine parts. The center support allows as described below 2nd extremely precise clamping and machining of a workpiece. For example, the encoder connection for motors must be manufactured with high precision.

1a-c show a perspective view, a side view and a plan view of the center support 2nd according to a preferred embodiment. 8th shows a perspective view of an exemplary vertical machining device 80 with such a center support 2nd . Alternatively, the center support 2nd can also be used with a horizontal machining device. The center support 2nd is through a console 6 at the processing facility 80 or on a base body 82 the processing device 80 stored. In this embodiment, the center support 2nd vertical (axial or in the direction of the axis M the center support) can be moved on the main body 82 the processing device 80 stored. At the console 6 are a first, second and third fluid inlet 56 , 58 , 60 arranged, through which hydraulic oil and compressed air can be admitted or discharged. There are three grease nipples for lubrication 55 offset by 120 ° on the chuck 4th intended.

In one case 7 the center support 2nd is a chuck 4th with a set of clamping segments 8a-c with clamping surfaces 64a-c ( 3a) arranged to clamp a workpiece to be machined (not shown). As in 1a you can see the clamping segment set 8a-c axially springing back to the housing 7 formed so that a central opening or recess 62 provided. The recess 62 is designed or dimensioned so that a main spindle 84 or a chuck 90 the main spindle 84 the processing device 2nd into the opening 62 can immerse. This means that even very short workpieces can be very close to the clamping segment set 8a-c held and edited. When machining, a workpiece can thus be at one end of the main spindle 84 the processing device 80 or its chuck 90 held and driven and additionally in the center support 2nd are supported so that the workpiece can be processed with high precision, for example, at its (lower) free end.

2a-d show sectional partial views of the center support 2nd in clamping position ( 2a , 2 B) and open position ( 2c , 2d ). The clamping segment set 8a-c is in a hollow spindle shaft 18th arranged. The spindle shaft 18th is about two axially spaced ball bearings 38a-b around the axis M the center support 2nd rotatable in the housing 7 arranged. Two spindle bearings or ball bearings are used for high machining precision at high speeds 38a , 38b with mutually inclined clamping levels ( 2a - dashed lines) are used. Unless otherwise stated, the terms “axial” and “radial” used here refer to the (rotation) axis M of the center support 2nd that when used in a machining facility 80 coincides with the drive axis A the main spindle 84 .

Between the clamping segments 8a-c and the inside 24th ( 4b) the spindle shaft 18th is a clamping cylinder 10th arranged. The clamping cylinder 10th points parallel to the axis M outstanding clamping wedges 12a-c ( 4a) on, each clamping segment 8a-c one wedge each 12a-c assigned. It is on the clamping wedges 12a-c first each (inwards to the axis M facing) wedge surface 14a-c and on the clamping segments 8a-c on the back (to the outside of the axis M groundbreaking) second wedge surface 16a-c educated. The first and second wedge surfaces 14a-c , 16a-c are plane or plane-parallel and are in contact with each other.

By moving axially (ie parallel to the axis M ) of the clamping wedges 12a-c becomes a radial movement of the clamping segments 8a-c causes. When the wedges 12a-c axially in the direction of their wedge tip (ie upwards in the figures), the clamping segments close 8a-c , so that a workpiece is clamped or clamped. When the wedges 12a-c are moved axially in the direction opposite to the wedge tip, the clamping segments open 8a-c or the clamping segments move 8a-c radially outward so that a clamped workpiece is released.

4a-b show perspective views of the spindle shaft 18th and the clamping cylinder 10th to illustrate how the clamping cylinder 10th in the spindle shaft 18th is arranged. The clamping cylinder 10th points in addition to the clamping wedges 12a-c parallel to the axis M outstanding support segments 26a-c on. If the clamping cylinder 10th into the spindle shaft 18th is inserted and the clamping cylinder 10th is actuated or a workpiece is clamped in the center support, the support segments lie 26a-c and the outside 13a-c the wedges 12a-c on the inside 24th the spindle shaft 18th all over. At the same time, the flat wedge surfaces lie 14a-c , 16a-c the wedges 12a-c and the clamping segments 8a-c together. The plans or plane-parallel wedge surfaces 14a-c , 16a-c that the tension cylinder 10th against the clamping segment set 8a-c not twist and so the wedge surfaces 14a-c , 16a-c always lie flat against each other. Overall, the radial clamping force of the center support can 2nd work all around and evenly on a clamped or clamped workpiece. Because in the tensioned state of the center support 2nd the clamping segments 8a-c who have favourited The Wedges 12a-c and the spindle shaft 18th always rest against each other (full surface), the radial play is eliminated or not available in the tensioned state. Therefore, a workpiece can be machined with high precision after clamping / clamping.

The wedges 12a-c are slightly elastic or flexible in the radial direction, so that when clamping a workpiece it is always guaranteed that the clamping wedges 12a-c on the inside 24th the spindle shaft 18th issue.

5 shows perspective views of the clamping cylinder 10th with the clamping segment set 8a-c assembled (right) and separated from each other (left). At the back of each clamping segment 8a-c are side guides 32a , 32b formed between which the wedge surface 16a-c of the clamping segment 8a-c lies. These tours 32a , 32b form a seat or a groove for each clamping wedge 12a-c and facilitate the correct positioning of the clamping wedges 12a-c relative to the clamping segments 8a-c .

On two adjacent support segments 26a-c of the clamping cylinder 10th are return slants 28a-f trained in appropriately designed return slopes 30a-d of the clamping segments 8a-c intervention. The slopes 28a-f , 30a-d ensure that even during opening and closing of the center support 2nd the plane-parallel position of the wedge surfaces 14a-c , 16a-c is secured.

The center support 2nd has an automatic operating device in one direction with a plurality of compression springs 20th ( 2a , 3b) to actuate the clamping segment set 8a-c on. The preload of the compression springs 20th causes the clamping segments to close automatically 8a-c as described below. The compression springs 20th are in a variety of parallel to the axis M trending holes 22 ( 4b) the spindle shaft 18th added. As in 2a the feathers can be seen 20th or acts the spring force of the springs 20th on a circumferential flange 11 of the clamping cylinder 10th so the tension cylinder 10th axially in the direction of the wedge tips of the clamping wedges 12a-c (up) is moved. This closes the clamping segments 8a-c for clamping a workpiece up to the clamping surfaces 64a-c of the clamping segments 8a-c rest on the workpiece. This closed position of the center support 2nd by the actuator or the springs 20th is effected (without workpiece) in 2a and 2 B shown.

To the clamping segments 8a-c to solve or to bring into an open position as in 2c shown, has the center support 2nd an actuator with an annular piston 40 or disc piston. The tensioning cylinder is by means of the actuator 10th against the spring force of the springs 20th axially displaceable. The actuator is on the fixed part of the center support 2nd arranged, ie it does not rotate with the chuck. When the center support is at a standstill 2nd or the main spindle 84 becomes the ring piston 40 hydraulically operated to the clamping cylinder 10th against the feathers 20th to actuate or to move axially. The ring piston points to this 40 a circumferential hydraulic seal on its inner circumference 42 on that in a seal receptacle 43 of the housing 7 intervenes. The seal 42 can be fed through two feed channels opposite each other by 180 ° 48 and an annular groove 46 with hydraulic oil or pressure. By providing two opposite feed channels 48 Even distribution of the hydraulic oil and thus the pressure is ensured, so that the ring piston tilts 40 is avoided. For loosening the clamping segments 8a-c becomes the ring piston 40 hydraulically operated until a contact surface 50 of the piston 40 on a contact surface 52 on the flange 11 of the clamping cylinder 10th is applied and then the clamping cylinder 10th with the wedges 12a-c axially actuated until it is in the open position ( 2c ). The maximum axial piston stroke c is in 2c featured.

To release the actuated ring piston 40 the pressure from the hydraulic channels 48 drained so that the spring force of the springs 20th the clamping cylinder 10th moved back to the closed position / clamped position ( 2a , 2 B) . The spindle shaft rotates during workpiece machining 18th with the clamping cylinder 10th and the clamping segments 8a-c around the axis M , with the ring piston 40 with the housing 7 stop. Around the ring piston 40 removed from the rotating parts of the center support during workpiece machining 2nd to hold the ring piston 40 via a circumferential seal located on its outer circumference 44 preferably pneumatically operated so that the piston 40 axially away from the clamping cylinder 10th is operated or moved. The seal 44 is in one shot 45 of the housing 7 added with the seals 42 , 44 of the ring piston 40 in the recordings 43 , 45 act in axially opposite directions or be pressurized in axially opposite directions.

The on the inner circumference and on the outer circumference of the ring piston 40 lying areas 54a , 54b , the to the seals 42 , 44 connect, are spherical segment-shaped, ie they have a convex curvature. These spherical segment-shaped / convex surfaces 54a , 54b ensure that even in the event of an unintentional tilting position ( 2d ) of the ring piston 40 , the sealing gap between the ring piston 40 and housing 7 remains and thus the ring piston 40 in the housing 7 cannot wedge / jam.

2nd shows an unlikely extreme case in which the piston in this embodiment is tilted by a maximum of 1.5 °, but the sealing gap between the hydraulic seal 42 and recording 43 due to the convex surface 54b is still there.

3a shows a plan view of the spindle shaft 18th with the clamping cylinder 10th and the clamping segment set 8a-c and 3b shows a cross section along the line AA the view of 3a . The clamping segment set 8a-c lies on one side (the underside) on a guide ring 36 on and is on the axially opposite side with a lock washer 34 secured. In 3a-b are the clamping segments 8a-c shown in the closed position, ie the clamping cylinder 10th is from the feathers 20th axially shifted in the wedge direction (upwards) so that the clamping segments 8a-c are shifted radially inwards.

As described above, the axial movement of the clamping wedges 12a-c a radial movement (clamping stroke) of the clamping segments in the direction of their wedge tip 8a-c to the axis M the center support, so that a workpiece from the clamping segment set 8a-c is clamped. The maximum possible clamping stroke is small and can be determined by the wedge angle or angles a can be set (wedge angle in relation to the axis M ). Wedges 12a-c or clamping segments 8a-c with a wedge angle a of eg 5 ° result in a smaller clamping stroke than a wedge angle a of 15 °, for example. For example, a clamping stroke between 5 mm and 10 mm can be provided. Since the maximum clamping stroke is very limited, clamping segments must be adapted to the workpiece diameter 8a-c with appropriately dimensioned clamping surfaces 64a-c or inner diameters can be used. Ie the clamping segments 8a-c must be adapted or changed to the workpiece to be machined.

The clamping segments are so that this change can be made as quickly and easily as possible 8a-c preferably formed in two parts as in 6a-f and 7a-g shown. The clamping segments 8a-c are divided radially into a cocking slide 70 with the wedge surface described above 16a and an interchangeable jaw 68 with the clamping surface 64a for one workpiece. This means that when changing the clamping segment, only the interchangeable jaw needs to be changed 68 be replaced and the cocking slide 70 can in the center support 2nd remain installed. The two parts are over a keyway 74 ( 7a) on the cocking slide 70 and a wedge pin 76 ( 7a) on the interchangeable jaw 68 connected to each other in the radial direction. The keyway also runs 74 and the wedge pin 76 conical at an angle in the axial direction b ( 6c ) too. To secure the connection is on the cocking slide 70 in the keyway 74 an axially aligned screw 72 provided that in a screw receptacle 75 of the cocking slide 70 intervenes. The interchangeable jaw 68 has a recess 78 ( 7a) for the screw 72 and the screw mount 75 on. After inserting the interchangeable jaw 68 in the keyway 74 of the cocking slide 70 ( 7f) becomes the screw 72 dressed. The interchangeable jaw points in the recess 78 an investment area 77 for the (tip of) screw 72 on so that when tightening the screw 72 the interchangeable jaw 68 in their final position ( 6e) pushed and at the same time by the screw 72 is secured in this position. For loosening the interchangeable jaw 68 becomes the screw 72 loosened until the interchangeable jaw 68 from the keyway 74 can be removed. The screw 72 does not have to be removed completely, but can be in the screw holder 75 remain. The screws are preferably seated 72 when using the center support 2nd a vertical machining device 80 above, so the interchangeable jaw 68 upwards from the center support 2nd can be removed. When changing the jaw 68 or loosen the screw 72 the risk of the interchangeable jaw slipping out and falling down unintentionally 68 from the keyway 74 eliminated. Depending on requirements, a two-part clamping segment can also be designed so that the interchangeable jaw can be removed downwards and the screw points downwards.

The following is a preferred embodiment of a main spindle unit 83 for a processing device, in particular the processing device described above 80 , explained.

9a-b show perspective views of the main spindle unit 83 which is a housing 92 with a main spindle arranged in it 84 (Turning spindle), as well as a stop spindle device with a stop spindle 96 and a stop tip 97 ( 12a-b ) or centering tip. The main spindle 96 is powered by an engine 85 driven. The stop tip 97 lies within a chuck 90 , so that it provides a stop for a workpiece to be clamped or already clamped (not shown). That is, by means of the stop spindle device, a workpiece can be held in the chuck before and also after clamping 90 are held in a predetermined axial position.

To the arrangement of the stop spindle device in the main spindle unit 83 is to illustrate in the views of 10a-c and 11a-b the main spindle unit 83 from 9a-b without the main spindle 84 shown. In 10a is the housing 92 and the main spindle 84 indicated by dashed lines. 10b shows a sectional view along the line BB in 10a . Stop spindle 96 and stop tip 97 are coaxial in a hollow shaft (not shown) of the main spindle 84 arranged. The stop spindle 96 is by means of an NC spindle drive, which is an NC motor 100 has axially movable in the main spindle unit 83 stored. In this embodiment, the stop spindle 96 via a ball screw drive with the motor 100 connected. This is the stop spindle 96 designed as a ball screw, which has a spindle nut 98 , a timing belt 104 , a pulley 99 and a pulley 99 with a drive shaft 102 of the NC motor 100 connected is. The stop tip can be operated via the NC spindle drive 97 move axially and thus be positioned exactly in a desired (axial) target position.

The stop spindle device also has a torque arm 108 to compensate for torques that occur during workpiece machining. It is on the stop spindle 96 the torque arm 108 with two opposite support rollers 110a-b ( 1 1b, 10c ) attached or fixed. In a torque support housing 118 are two corresponding slot-shaped support roller guides 112a-b trained parallel to the stop spindle 96 run and thus the stop spindle 96 about the roles 110a-b support in any axial position. On the support housing 118 are along the guides 112a-b several adjustment screws 114a-b arranged to the leadership game of the guides 112a-b set exactly.

A clamping device of the main spindle unit 83 has a hollow clamping cylinder 94 on that below the torque arm 108 is arranged. The hollow clamping cylinder 94 is via a connecting flange 106 with the main spindle 84 connected. By means of the hollow clamping cylinder 94 becomes a draw tube 124 and an associated stop housing 128 ( 12b-c ) axially actuated to a workpiece in the chuck 90 to clamp.

12a shows a view of the main spindle unit 83 from 10b from underneath, 12b a sectional view along the line AA in 10a , and 12c shows a sectional view along the line DD in 12a in the lower area of the spindle unit 83 .

The stop spindle device has a stop quill 130 on, in the stop tip 97 is fixed, the quill 130 in a guide tube 127 is guided axially. The quill 130 and with it the stop tip 97 is coupled to the driven main spindle shaft and therefore rotate with the main spindle 84 With. Around the rotating quill 130 from the stop spindle (in the direction of rotation) 96 decoupling is the quill 130 over several angular contact ball bearings 134a-c ( 12d ) on the stop spindle 96 stored. Between the (rotating) stop tip 97 and the stop spindle 96 is a rotary seal 132 arranged for a flushing medium. Because the stop tip 97 with the main spindle 84 or the workpiece clamped in it, the stop tip can 97 remain attached to a workpiece throughout a workpiece machining. This is also the case during workpiece machining (after clamping in the chuck 90 ) the axial position of the workpiece is secured. Below the quill 130 is a seal 142 arranged around the guide tube 127 or the guidance of the quill 130 in the guide tube 127 Protect against contamination during workpiece machining.

13a-b show a perspective view and a sectional view of part of the clamping device of the spindle unit of FIG 9a-b which rotate with the rotating spindle and additionally when the clamping device or the hollow clamping cylinder is actuated 94 be operated axially. Due to the axial actuation, workpieces can be chucked 90 be excited. For this, the draw tube 124 that with the stop housing 128 is connected axially from the hollow clamping cylinder 94 operated. The chuck clamping stroke d or the clamping stroke d of the hollow clamping cylinder 94 is in 12b marked. A star-shaped connecting part 145 is by means of screws 146 to the stop housing 128 screwed on. On the stop housing 128 is a mounting flange 120 for fastening the main spindle 84 and a chuck flange 122 for fastening the chuck 90 arranged. One of the screws 144 for fastening the main spindle 84 on the flange 120 is in 12c indicated schematically. At the lower end of the stop housing 128 is a connection thread 140 for the chuck 90 educated.

14a-b show a perspective view and a sectional view of the part of the stop spindle device of FIG 9a-b that coaxial in the in 13a-b shown part of the clamping device is arranged. In the 14a-b parts shown are firmly connected to the rotating spindle and rotate exclusively, ie they are not like that in 13a-b parts shown actuated axially. Inside the stop housing 128 is the guide tube described above 127 with quill 130 and stop tip 97 arranged. Opposite the stop tip 97 connects to the guide tube 127 a stop sleeve 126 at. Via a connecting ring 121 is the guide tube 127 firmly with the Mounting flange 120 connected. When assembled ( 12b-c ) the star-shaped connecting part protrudes 145 through the connecting ring 121 through and is together with the stop housing 128 and the connecting thread 140 axially displaceable therein.

The stop sleeve 126 is used to reference the position of the stop spindle unit or to zero the axis. For this purpose forms a surface on the inside of the stop sleeve 126 a homing stop 136 for one on the quill 130 trained referencing surface 138 out. The quill is used for a reference run to zero the axis 130 Use the spindle drive to move axially (upwards) until the reference surface 138 at the homing stop 136 is present. A reference run may be necessary, for example, due to changes in length by heating the stop spindle device.

The following is an example of a method for clamping and machining a workpiece with a machining device 80 ( 8th ), which has a center support as described above 2nd and a main spindle unit as described above 83 having. The processing facility 80 points as in 8th shown a basic body 82 on which the center support 2nd is mounted, in particular is axially movable. The main spindle unit 83 is preferably fixed (not movable) on the base body 82 attached and opposite to the main spindle 84 is an axially movable tailstock 86 with center point 87 attached. In an embodiment, the main spindle unit can also 83 towards the main body 82 be axially (eg vertically) slidably mounted. Center support 2nd and tailstock 86 are coaxial to the drive axis A the main spindle 84 aligned.

Before clamping a workpiece in the machining device 80 a reference surface is created on the workpiece. This reference surface per se and the above reference stop 136 are independent of each other, however, the adjustment or referencing of the stop spindle device is used to reproducibly align the z position (with vertical axis) or axial position of a workpiece, so that clamping using the center support can take place exactly on the reference surface. For this purpose, a centering hole is formed at the workpiece ends, via which the workpiece is clamped, for example, in a grinding machine. A highly precise reference surface (circumferential plane surface / fit) is then generated at a desired location on the workpiece circumference, which serves as a reference for all subsequent machining operations.

First, the stop spindle device or the stop tip 97 move to an axial target position. Optionally, a reference travel of the stop spindle device as described above can be carried out beforehand. The center support can also be optional for longer workpieces 2nd axially to the tailstock 86 be moved until the center point 87 of the tailstock 86 through the center support 2nd or the clamping segments 8a-c protrudes through. This hinders the center support 2nd not inserting the workpiece.

The target position of the stop tip 97 is determined by the position of the reference surface formed on the workpiece to be machined on the center support 2nd then clamps the workpiece. Respectively. the target position of the stop tip 97 is determined by the clamping position of the center support 2nd on the main body 82 .

Then the workpiece is centered between the stop tip 97 and the center point 97 of the tailstock 86 clamped by the tailstock 86 is moved axially until the workpiece touches the stop tip 97 is present. Until then, using the hydraulic actuator or the clamping cylinder 18th open center support 2nd can now by releasing the pressure on the springs 20th are operated automatically, so that the clamping segments 8a-c clamp the workpiece on the reference surface. If the center support 2nd the center support is moved out of the way beforehand 2nd before operating the clamping segments 8a-c move axially into the clamping position. Because the workpiece is used both when generating the reference or plane surface and when clamping in the center support 2nd fixed / positioned by means of the same centering holes, the dimensional accuracy is maintained during machining despite the reclamping of the workpiece. In addition, the extremely stable clamping in the center support described above 2nd the dimensional accuracy of the machining is further increased.

Finally, the workpiece end is in the chuck 90 the main spindle 84 clamped and optionally the tailstock 86 moved away from the opposite end of the workpiece, e.g. for end machining.

The workpiece that is now clamped can be processed using the tools of the machining device 80 to be edited. In this configuration, tool turrets are used 88a-b drilling, turning, milling and / or grinding tools on the base body that can be fed in with the workpiece 82 Can be moved in the x and z directions and optionally in the y direction (see coordinates in 8th ).

Reference symbol list

2nd

Center support

4th

Chuck

6

console

7

casing

8a-c

Clamping segment

10th

Clamping cylinder

11

Flange clamping cylinder

12a-c

Wedge

13a-c

Contact surface clamping wedge

14a-c

Wedge surface clamping wedge

16a-c

Wedge surface clamping segment

18th

Spindle shaft

20th

Compression spring

22

Bore for compression spring

24th

Inside / surface of spindle shaft

25th

Drainage hole

26a-c

Support segment

28a-b

Return bevel clamping cylinder

30a-d

Return bevel clamping segment

32a-d

lateral guidance

34

Lock washer

36

Guide ring

38a-b

ball-bearing

40

Ring piston

42

Hydraulic seal

43

Seal holder

44

Pneumatic seal

45

Seal holder

46

Ring groove hydraulic oil

48

Hydraulic oil supply channel

50

Piston contact surface

52

Contact surface clamping cylinder

54a-b

Spherical segment (arch)

55

Grease nipple

56

First fluid inlet

58

Second fluid inlet

60

Third fluid inlet

61

Lubrication channel

62

Opening / recess

64a-c

Clamping surface clamping segment

68a-c

Interchangeable jaw

70a-c

Cocking slide

72

screw

74

Keyway

75

Screw holder

76

Wedge pin

77

Screw contact surface

78

Cut-out for screw

80

Machining device

82

Basic body

83

Main spindle unit

84

Main spindle

85

Motor / drive

86

Quill / tailstock

87

Centering tip

88a-b

Tool turret

90

Chuck

92

casing

94

Hollow clamping cylinder

96

Stop spindle

97

Stop tip

98

Spindle nut

99

Pulley

100

NC motor

102

Motor shaft

104

Timing belt

106

Connecting flange

108

Torque arm

110a-b

Support roller

112a-b

Support roller guide

114a-b

Set screw

116

Flushing medium connection

118

Torque support housing

120

Flange spindle mounting flange

121

Connecting ring

122

Chuck flange

124

Draw tube

126

Stop sleeve f. Homing

127

Guide tube f. attack

128

Stop housing

130

Stop quill (rotating)

132

Rotary seal

134a-c

Angular contact ball bearings

136

Referencing stop

138

Referencing surface

140

Connection thread chuck

142

poetry

144

screw

145

Connecting part

146

screw

148

drilling

A

Drive shaft spindle shaft

M

Axis center support

x

height

a

Angle wedge surface

b

Angle wedge mount

c

Piston stroke

d

Collet chuck stroke

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 1510275 B1 [0002]

Claims (15)

Center support (2) for supporting and / or clamping a workpiece to be machined, the center support (2) having: a chuck (4) rotatably mounted about an axis (M) with a set of clamping segments (8a-c) for clamping a workpiece on a peripheral area, a hollow spindle shaft (18) in which the clamping segment set (8a-c) is arranged, the spindle shaft (18) being rotatably supported in the center support (2) on two axially spaced apart bearings (38a-b); and an actuating device for actuating the clamping segment set (8a-c), wherein the actuating device has at least one spring element (20) which, due to its pretension, closes the clamping segment set (8a-c) for clamping a workpiece, the actuating device having a set of clamping wedges (12a-c) and a respective clamping wedge (12a-c) being arranged between each clamping segment (8a-c) and the spindle shaft (18), wherein each clamping wedge (12a-c) has a first wedge surface (14a-c) and the associated clamping segment (8a-c) has a second wedge surface (16a-c) resting on the first wedge surface (14a-c), and wherein the first and second wedge surfaces (14a-c, 16a-c) are flat and / or plane-parallel. Center support after Claim 1 , wherein the wedge surfaces (14a-c, 16a-c) to the axis (M) of the center support (2) have an angle between 4 ° to 20 °, preferably an angle between 5 ° to 8 °, 8 ° to 10 °, 10 Have ° to 12 °, 12 ° to 15 °, or 15 ° to 20 °, and / or wherein each clamping segment (8a-c) has a maximum radial clamping stroke between 5 mm to 10 mm. Center support after Claim 1 or 2nd , wherein the center support (2) has a tensioning cylinder (10), and wherein the tensioning wedges (12a-c) are arranged on the tensioning cylinder (10), in particular are formed in one piece with the tensioning cylinder (10), and / or wherein the tensioning wedges (12a -c) axially protruding / excellent on a clamping cylinder (10) of the center support (2). Center support after Claim 1 , 2nd or 3rd , wherein the clamping wedges (12a-c) are flexible radially to the axis (M) of the center support, so that the clamping wedges (12a-c) rest / rest on the inside (24) of the spindle shaft (18) when clamping a workpiece, in particular flat rest, and / or wherein the clamping wedges (12a-c) are flexible in the radial direction, so that when a workpiece is clamped, the first wedge surface (14a-c) lies flat on the second wedge surface (16a-c). Center support according to one of the preceding claims, wherein the center support (2) has an actuator (40-52) which acts to release the clamping segments (8a-c) on the at least one spring element (20). Center support after Claim 5 , wherein the actuator (40-52) is slidably mounted within a fixed housing (7) of the center support (2) and can be actuated hydraulically; and / or wherein the actuator (40-52) acts on the clamping segment set (8a-c) via the clamping cylinder (18); and / or wherein the actuator (40-52) has an annular piston (40), in particular a disk-shaped annular piston. Center support according to one of the preceding claims, wherein the center support (2) has a smaller axial extent in the area of the clamping segment set (8a-c) than in the area of the spindle shaft (18) and the clamping cylinder (10), and / or wherein the center support (2) is designed to spring back axially in the area of the clamping segment set (8a-c), in particular in the area of the clamping segment set (8a-c) forming a recess (62) so that a chuck (90) of a main spindle (84) in the recess is submersible. Center support according to one of the preceding claims, wherein the clamping segment set (8a-c) is interchangeably and / or removably mounted, and / or wherein each clamping segment (8a-c) has a clamping slide (70a-c) and an interchangeable jaw (68a-c) detachably connected to the clamping slide (70a-c), the second wedge surface (16a-c.) on the clamping slide (70a-c) ) and on the interchangeable jaw (68a-c) a clamping surface (64a-c) is formed for a workpiece to be machined. Spindle unit (83) for a machining device (80), the spindle unit (83) comprising: a main spindle shaft (84) rotatably mounted in a housing (92), a motor drive (85) connected to the main spindle shaft (84) for driving the main spindle shaft a drive axis (A), a clamping device (90) arranged on the main spindle shaft (84) with a chuck for clamping a workpiece, a stop spindle device (96, 97) coaxially mounted on the main spindle shaft (84) with a stop spindle (96) and a stop tip (97), and a spindle drive (100) connected to the stop spindle device for axially moving the stop tip (97) into a desired position in order to position and / or axially secure a workpiece before and / or after clamping in the clamping device (90). Spindle unit after Claim 9 , wherein at least the stop spindle (96) is decoupled from the motor drive (85) in the main spindle shaft (84), so that at least the stop spindle (96) is mounted in the main spindle shaft without rotation, and / or at least the stop spindle (96) is only axial is movable. Spindle unit after Claim 9 or 10th , The stop spindle device has a guide housing (126, 127) in which the stop spindle (96) and / or the stop tip (97) is mounted so as to be axially movable, the guide housing (126, 127) with the main spindle shaft (84) and / or the tensioning device (90) is connected in a rotationally fixed manner. Spindle unit after Claim 9 , 10th or 11 , with a hollow sleeve (130) which is axially displaceably mounted in the guide housing (127, 126), the hollow sleeve (130) being rotatably mounted on the stop spindle (96) on at least two axially spaced bearings (134), the stop tip (97) in particular and the hollow quill (130) is connected in a rotationally fixed manner and the stop tip (97) protrudes from the hollow quill (130) in the direction of the chuck (90). Spindle unit after Claim 12 The spindle unit (83) has a referencing device (136, 138) with a referencing surface (138) formed on the hollow sleeve (130) and an axially spaced referencing stop (136) formed on the guide housing (126). Machining device (80) with (A) a base body (82), a spindle unit (83) mounted on the base body (82), which has a stop spindle device (96, 97) according to one of the preceding Claims 9 to 13 and, optionally, a tailstock (86) mounted on the base body (82) and opposite the spindle unit (84), a workpiece preferably being clampable between a stop tip (97) of the stop spindle device and the tailstock (86); and / or (B) a center support (2) according to one of the Claims 1 to 8th Method for clamping and machining a workpiece in a machining device (80), the machining device (80) comprising: a base body (82), a spindle unit (83) mounted on the base body (82), which has a stop spindle device (96, 97) with a Stop spindle (96) and stop tip (97) according to one of the preceding Claims 9 to 13 has, on the base body (82), the spindle unit (83) axially opposite tailstock (86), between the spindle unit (83) and tailstock (86) on the base body (82) mounted center support (2) according to one of the Claims 1 to 8th , the method comprising the steps of: axially moving the stop tip (97) into a desired position, (97), inserting a workpiece between the tailstock (86) and the stop tip, clamping the workpiece by axially moving the tailstock (86), clamping the workpiece in the center support (2), (83), clamping a workpiece end in a chuck (90) of the spindle unit, removing the tailstock (86) from the workpiece by axial movement, machining the workpiece.

Images