EP1303374A1

EP1303374A1 - Machine tool

Info

Publication number: EP1303374A1
Application number: EP01960524A
Authority: EP
Inventors: Walter Dengler; Armin Thierfelder
Original assignee: Boehringer Werkzeugmaschinen GmbH
Current assignee: MAG IAS GmbH Eislingen
Priority date: 2000-07-21
Filing date: 2001-07-20
Publication date: 2003-04-23
Also published as: WO2002007920A1; DE10035718A1

Abstract

Known headstocks are relatively long since clamping chucks, the rotationally mounted spindle and the clamping cylinder etc are situated axially behind each other. The invention provides for a shortening of the headstock by accommodating the clamping cylinder inside the spindle, whose inner diameter is increased. The clamping cylinder and chuck are also fixed to each other directly and preassembled and performance-tested as a module. This configuration is particularly advantageous for an integrated spindle motor since the increased outer diameter of the spindle (the winding diameter) has a positive effect on the torque of an integrated motor of this type.

Description

machine tool

I. Field of application

The invention relates to lathes and other machine tools in which the workpiece is rotatably received by a workpiece spindle, and to a method for producing in particular the headstock of such a machine.

II. Technical background

Machines that hold the workpiece in a drivable manner during processing, such as lathes, broaching machines, turning-milling machines, cylindrical grinding machines, each have at least one workpiece spindle with which the workpiece is firmly connected. The workpiece spindle is driven by a spindle motor at the desired speed.

Depending on the machining process, high speeds of up to 10,000 revolutions per minute and more are required, in return, however, low torques are required when driving the workpiece, with other processes, however, relatively high torques of, for example, 2,500 - 3,500 N / m at comparatively low speeds of up to approximately 50 or 100 rpm.

The longer and thinner and thus less stable a workpiece, the higher the need to have the workpiece picked up and driven by such a spindle at both ends. They are a typical example comparatively unstable crankshafts, as are required in reciprocating internal combustion engines.

The attachment of the workpiece end to the workpiece spindle is usually done with the help of a chuck, which is non-rotatably arranged on the workpiece spindle and has clamping elements for holding the workpiece. As a rule, these are the known, radially movable clamping jaws of a three-jaw chuck, for example, which are moved evenly radially inwards and press against the outer circumference of the workpiece in the end region, as a result of which the workpiece is connected to the chuck in a rotationally fixed and axially fixed manner.

The clamping force is usually applied hydraulically by applying pressure to a clamping cylinder that is aligned with the axis of rotation of the chuck. The longitudinal displacement of the clamping piston in the clamping cylinder causes - as a rule translated by means of a wedge gear - the radial displacement of the clamping jaws, including a strengthening.

The spindle is usually designed as a hollow tube, which is rotatably mounted in the headstock housing, on the front end of which the chuck is seated, while the clamping cylinder is arranged on the rear end. Both parts rotate together with the workpiece spindle.

The longitudinal movement of the clamping piston is transmitted to the chuck by means of tie rods or draw tubes that run through the inside of the workpiece spindle, since efforts have been made to avoid the necessary storage, usually a roller bearing, between the spindle and the headstock housing to grow up. On the rear end of the clamping cylinder, the rotary distributor for the hydraulic oil was also arranged - again axially lined up - as well as the non-rotating supply flange to which the hydraulic oil lines were connected. The rotary distributor transfers the stationary supply flange to the rotating clamping cylinder.

In a machine for machining car crankshafts, which have an axial length of approximately 80 cm, this arrangement leads to a length of such an assembled headstock of approximately 2.30 m. With two headstock units per machine at the two ends of the workpiece, this results in a total length of the machine of approx. 5 ^Λ A m.

In relation to the small longitudinal extension of the workpiece, a large amount of space is required in the longitudinal direction of the workpiece for such a machine, which has a negative effect particularly when such a machine is integrated into a production line.

The transverse arrangement of the machine within the line is also not a solution, since on the one hand a 90 ° swivel of the otherwise longitudinally transported workpiece before and after this transverse machine tool would be necessary, and on the other hand such a transverse position within the machine line at one point would result in a much greater width than the other width of the line of approx. 2 m.

III. Presentation of the invention

a) Technical task

It is therefore the object of the present invention to provide a machine tool and a method for its production, in which the axial length of the machine tool is significantly less than before, in spite of as little design and construction expenditure for the machine as possible. b) solving the problem

This object is achieved by the characterizing features of claim 1. Advantageous embodiments result from the subclaims.

Since the axial length of today's machine designs is primarily determined by the axial extension of the headstock units, the goal is achieved by reducing the axial length of the one or two headstock units.

For this purpose, the axial length of the already hollow workpiece spindle is used to accommodate components or parts of the components that were otherwise located in front of and behind the workpiece spindle, for example the clamping cylinder.

In principle, this is already known from the so-called front end chucks. In such a front end chuck both the chucking function of the chuck and the causing movement of the clamping cylinder are integrated, and the resulting front end chuck partially projects into the front end of the workpiece spindle.

A disadvantage of this solution, however, is that there is no longer a clear separation of the chuck functions and the clamping cylinder functions, and the large functional density of the functionally combined components means that there is a complicated component which is problematic in terms of troubleshooting. The risk of leaks and their location in the hydraulic part of the front end chuck is also relatively high.

Furthermore, a special design of the workpiece spindle must be observed, since its inner diameter must be larger in the front end area than in the rear end. Because of the combination of functions, tried-and-tested, mass-produced standard components with regard to chuck, clamping cylinder, rotary distributor and supply flange cannot be used.

Instead, it is proposed according to the invention to arrange the chuck and clamping cylinder axially one behind the other and in terms of their functions as before, but without or with a significantly smaller axial distance from one another than before, and the clamping group thus created at least partially in the length range of the workpiece spindle, namely in the hollow interior of the workpiece spindle to accommodate. For this purpose, the diameter of the workpiece spindle is dimensioned much larger than before.

Since the clamping cylinder generally has the smaller outside diameter with regard to the chuck and the clamping cylinder, this is accommodated in the interior of the workpiece spindle, while the chuck sits on the front end of the workpiece spindle as before.

However, the clamping group consisting of chuck and clamping cylinder, possibly also comprising a rotary distributor and supply flange, is preferably also pre-assembled as a clamping group from the assembly sequence and also functionally tested, and only then inserted into the workpiece spindle from the front. The chuck is screwed onto the front end of the workpiece spindle, preferably with its back plate.

It would also be possible to use the interior of the workpiece spindle directly as a clamping cylinder for the clamping piston.

Such a combination of functions would indeed result in a reduction in the diameter of the workpiece spindle compared to the installation of a complete clamping cylinder in the interior of the workpiece spindle, but on the other hand it would carry the typical consequential problems of a combination of functions, for example problematic definition of interfaces to components from suppliers

Repair and removal of the clamping cylinder / clamping piston make it necessary to remove the entire spindle

Depending on the size of the clamping force to be applied and the clamping path, the piston diameter and thus the inside diameter of the spindle must be adjusted.

Such a solution is therefore likely to be realizable only in practice by using cylinder liners with different, required diameters as an adapter in the same inner diameter of the workpiece spindle.

Apart from an additional necessary radial support in the spindle, which could be necessary, the insertion of a standard clamping cylinder, pre-assembled within the framework of the above-mentioned clamping group, and its penetration into the workpiece spindle is an analogous solution. However, this offers the advantages

Selection of the previously available, standardized and tried and tested individual parts with regard to chuck, clamping cylinder, rotary distributor and supply flange

- Adaptability to the conditions of the individual case by selection from the product range of such standard components

Ease of repair through separation of functions.

The large increase in the spindle diameter required with this solution is disadvantageous at first glance with regard to the costs of the larger bearing. On the one hand, the larger spindle diameter is advantageous for the better one Force absorption in the headstock housing and on the other hand also with regard to the usability of the spindle as a component of an integrated motor:

While in the conventional construction of a headstock, the spindle, which is rotatably mounted in the housing of the headstock, is driven by a motor gear, belt transmission or the like by a motor also present on the headstock housing, in the case of a so-called integrated motor, the spindle itself is a component of the electric motor, usually the rotor, and accordingly equipped on the outer circumference either with at least one electrical conductor, in particular in the form of windings, or with permanent magnets.

The surrounding headstock housing is designed analogously as a stator.

The torque that can be applied by such a motor increases with the nominal diameter of the stator / rotor, which facilitates the formation of an integrated motor and lowers its costs, particularly in the case of slow-running spindles such as the turning, turning and broaching machines.

The previous arrangement of electromechanical limit switches on the movement paths of moving components of the headstock, i.e. for example the clamping piston in the clamping cylinder or the clamping jaws in the chuck or also - in the case of movable headstocks - the headstock housing relative to the bed of the machine tool is inventively achieved by so-called magnetostrictive telemetric, optical or other measuring systems solved.

For example, it is an electrical conductor made of magnetostrictive material, which is usually arranged in a stretched manner along the movement path. The component to be moved has a magnet which is moved along the magnetostrictive conductor. By applying an electrical signal to the conductor - due to the interaction between the magnet and the current flowing in the magnetostrictive conductor - the signal obtained at the end of the magnetostrictive conductor and influenced by the magnet can be evaluated with regard to the current position of the magnet in the longitudinal direction of the conductor.

The telemetric transmission of measurement signals within the machine can also be used. The intended measurand is measured directly at the point of origin, for example the clamping force of the chuck against the workpiece by means of a strain gauge, which is arranged directly on the clamping jaw, instead of measuring the force of the clamping piston against the clamping cylinder. The measurement signal determined in this way is preferably transmitted wirelessly, by means of radio, infrared or other electromagnetic waves, to a receiver, preferably close to the control unit of the machine.

As a result, for example, in the case of position sensors along the spindle, the signal does not have to be conducted along the spindle to its end.

A foil antenna, for example, serves as the antenna for signal transmission, which can also be arranged on a rotating part of the machine, for example the chuck or the clamping cylinder, and transmits the signal to a receiver which is on a non-rotating part of the machine, for example on or in Spindle housing, is arranged. This avoids the mechanical or electrical wired signal transmission from a rotating to a non-rotating component.

In this way, not only positions of assemblies, but also compressive and tensile stresses as well as temperatures can be measured and transmitted.

This type of position monitoring makes it possible to enter the end positions into the machine control via software when they reach the Propulsion of the corresponding assembly is stopped automatically. In particular, it is possible to precisely monitor the position of the clamping piston in the clamping cylinder when the workpiece is clamped.

As a result, mechanical adjustment of electromechanical limit switches is no longer necessary, which would be particularly problematic when arranged on the cylinder and thus within the workpiece spindle. On the contrary, the workpiece spindle partially surrounding the clamping group can simultaneously be used as an electromagnetic shield for such magnetostrictive measuring systems, for example by coating the inner circumference of the workpiece spindle with shielding material. It is not possible to shield the open end faces as long as the rotary distributor and the supply flange protrude from the rear end of the workpiece spindle and the chuck from the front end.

However, it could be possible to provide the front opening of the interior of the workpiece spindle with a completely covering chuck, for example on the back of its back plate, with electromagnetic shielding material, and also to openly open the small central cross section required for the passage between the rotary distributor and the clamping cylinder let the other part of the cross-section of the rear opening of the workpiece spindle be sealed off electromagnetically.

Under certain circumstances, it could therefore also be advisable to also carry out the evaluation of the signals from the magnetostrictive position sensors in this shielded interior of the workpiece spindle, and from there to forward the fully evaluated and processed signal to the machine control. c) working examples

Embodiments according to the invention are described in more detail below by way of example. Show it:

Figures 1: The integration of the machine in production lines under supervision,

2: the representation of a machine according to the prior art in

Partial cut and

3: the machine tool according to the invention.

1 shows the basic dimensioning of a machine tool, in which the workpiece is driven in a rotationally drivable manner by one or two opposing workpiece spindles 2 during machining, in a top view.

Shown is a crankshaft processing machine with a rotary broaching unit and a rotary milling unit, in which the unstable crankshaft is received as a workpiece 20 at both ends by a headstock 12.

It can be seen that, above all, the axial extension of these headstocks 12 causes such a machine tool 1 equipped with a drivable workpiece spindle to be substantially larger in the axial direction of the workpiece 20 machined there than in the transverse direction thereof.

Fig. 1a shows the inclusion of such a. With a rotationally drivable workpiece spindle or its several equipped machine tool 1 in a production line with other workpiece machines V, 1 ", 1 '", whereby - which is the most common case - the workpieces from machine to machine are transported further in a direction of passage 30 and the workpieces 20 are oriented such that their longitudinal direction 10 coincides with this direction of passage 30. In this case, one with two drivable, Machine tools 1 equipped with mutually directed workpiece spindles have a significantly longer length within the production line than the other machines.

Fig. 1b shows a way to reduce the length requirement of the same production line. In this case, the machine tool 1 equipped with one or two rotationally drivable workpiece spindles is arranged in the production line in such a way that the workpiece 20 accommodated in the machine tool 1 lies with its longitudinal direction 10 transverse to the direction of travel 30 of the workpieces through the entire production line.

In this case, the space requirement and thus also the space requirement for the machine tool 1 in the longitudinal direction of the production line is lower, but additional space in the longitudinal direction in the line is required in order to provide turning devices 31 before and after this transverse machine tool 1, which fix the workpiece 20 turn by 90 ° for further handling. Another problem is the very high-rise control cabinets and loading devices, which are often attached to the back of such a machine tool 1 and in this case must also be overcome when delivering and removing workpieces.

It is clear from this that there is a need to shorten a machine tool 1 equipped with one or more rotationally drivable workpiece spindles 1 in the longitudinal direction 10.

Fig. 2 shows the previous structure of a headstock according to the prior art using a machine tool with only one tool support.

Fig. 3 shows designs of the headstock according to the invention.

2 shows a top view of a machine tool with two headstocks 12 facing each other. Otherwise, a tool system is present on the bed 18 of the machine, that is, as usual, a longitudinal slide 21 which runs in the longitudinal direction 10 along longitudinal guides 23 is movable. On the longitudinal slide 21, a cross slide 24 can be moved in the transverse direction, which carries the disk-shaped tool 25 in this case, namely a disk-shaped milling cutter with cutting edges on the circumference, which is rotatably supported in the cross slide 24.

The axis of rotation of the tool 25 is parallel to the axis of rotation, the Z direction, of the two headstocks 12, which between them accommodate the workpiece 20, a crankshaft with splitpin bearing journals, so that the longitudinal direction 10 of the crankshaft with the axis of rotation and thus Longitudinal direction of the headstocks 12 coincides.

The workpiece 20 is held on the circumference in the end regions by the jaws 5a, b .. of a chuck 4. The chuck 4 is fixed on the front face of a workpiece spindle 2, which is rotatably mounted in the housing 12 'of the headstock. The workpiece spindles 2 are driven in rotation by one or two separate motors, which are not shown in FIG. 2 for the sake of clarity.

A clamping cylinder 6 is arranged centrally on the rear end face of the workpiece spindles 2, which is located in the length range behind the spindle 2 and also behind the spindle housing 12 '.

The rotary distributor 8 and a supply flange 9 are arranged one after the other on the rear end face of this clamping cylinder 6. The supply flange 9 is used to fasten the supply lines for the functions of the headstock, mainly the hydraulic lines for loading the clamping cylinder 6 with hydraulic oil under pressure.

Since the chuck 4, the workpiece spindle 2 and the clamping cylinder 6 rotate together, while the supply flange 9 stands still, the rotary distributor 8 is necessary in between for forwarding the hydraulic oil from the fixed supply flange 9 into the rotating components. The workpiece spindle 2 is hollow throughout in the longitudinal direction, so that tie rods 13 run from the clamping cylinder 6 through this interior space 7 to the chuck 4, which transmit the movement of the clamping piston 16 in the clamping cylinder 6 to the chuck 4, in order to there the clamping jaws 5a, b .. to move radially relative to the chuck 4.

In contrast, FIG. 3 shows a shortened construction of the headstocks 12a or 12b with an otherwise analogous design of the machine tool 1.

As can be seen from the headstock 12 a, the workpiece spindle 12 mounted in the housing 12 'of the headstock has a substantially larger diameter, as a result of which the interior space 7 of the workpiece spindle 12, which is continuously open in the longitudinal direction 10, also becomes significantly larger.

The chuck 4 is still attached to the front face of the workpiece spindle 2, possibly via a back plate 11, but the enlargement of the interior space 7 now makes it possible for the element with the next smallest diameter compared to the chuck 4, namely the clamping cylinder 6 to record already in the inner diameter of the interior 7. The components in the longitudinal direction on the back of the clamping cylinder 6, namely the rotary distributor 8 and the supply flange 9, are even smaller in diameter and can therefore also be accommodated in the interior of the workpiece spindle 2. For reasons of stable mounting of the workpiece spindle 2, however, it is made so long and the spacing of the bearings in the axial direction 10 is increased such that only the supply flange 9 via the rear end of the housing 12 ′, which ends approximately in the same axial position, and the workpiece Spindle 2 protrudes.

This design also enables all components rotating together with the workpiece spindle 2, i.e. at least the chuck 4, which has the largest outer diameter, and the clamping cylinder 6, which generally follows immediately, optionally also the rotary distributor 8 and the supply flange 9 as a clamping group pre-assemble and check for function. This Clamping group can thus be procured completely from outside and only has to be inserted into the open front of spindle 2 in the factory in which machine tool 1 is manufactured and screwed there.

The drive of the spindle 2 in the headstock 12a takes place conventionally, that is to say via a toothing 14 arranged on the outer circumference of the spindle 2, in which a gearwheel 15 of a gear engages, which is connected in a rotationally fixed manner to the driving spindle motor 3, which sits on the housing 12 'of the headstock ,

The right headstock 12b differs from the left in the type of drive of the spindle 2:

In the headstock 12b, this drive takes place by means of a so-called integrated motor, the workpiece spindle 2 rotating relative to one another and the headstock housing 12 'forming the two parts of the electric motor that are movable relative to one another, that is to say the rotor and the stator. Correspondingly, windings of electrical conductors 19, 19 'are arranged in the outer circumference of the workpiece spindle 2 and in the inner circumference of the housing 12', which serve to convert electrical energy into kinetic energy in the form of a rotating drive of the workpiece spindle 2.

The larger diameter, also outer diameter, of the workpiece spindle 2 compared to the conventional design is advantageous in that the torque generated by this motor increases with increasing diameter of the motor windings of this integrated electric motor, so that such an embodiment is particularly suitable for machine tools, in which the workpiece 20 must be driven with high torques, but with low speeds.

Fig. 3 also shows in the right clamping cylinder 6, the tensioning piston 16 running therein, and a position measuring system, which also serves as a limit switch, and from a movable part, for. B. magnet 17b, which is arranged in the movable component, the clamping piston 16, and one along the cylinder wall in Clamping cylinder 6 arranged fixed part, for. B. an electrical conductor 17a made of magnetostrictive material.

By applying an electrical signal to the magnetostrictive conductor 17a from one end, the exact position of the magnet 17b with respect to the conductor 17a, which usually extends in the longitudinal direction 10, can be determined by an electronic evaluation circuit.

A control of the machine tool is coupled to the evaluation device, into which maximum positions for the magnet 17b in the longitudinal direction 10 can also be entered, upon reaching which the movement of the magnet 17b, in this case the clamping piston 16, is stopped by suitable measures, in this case by stopping the pressure oil supply.

This means that programmable limit switches for moving machine components can be implemented without having to adjust the position of electromechanical, physical limit switches.

The same magnetostrictive position monitors and limit switches are also for other components to be moved, for example the clamping jaws 5a, b .. with respect to the chuck 4, for the tool slide or - in the case of longitudinally movable headstock housings 12 '- for their position along the bed 18 of the machine tool possible.

LIST OF REFERENCE NUMBERS

1 machine tool 15 gear

2 workpiece spindles 16 clamping pistons

3 spindle motor 17 position sensor

4 chucks 17a conductor 5a, b, c jaw 25 17b magnet

6 clamping cylinders 18 bed

7 interior 19 electrical wiring

8 rotary distributors 20 workpieces

9 supply flange 21 longitudinal slide 10 longitudinal direction 30 22 rotor

11 back plate 23 longitudinal guide

12 headstock 24 cross slide

12 'housing 25 tool

13 tie rods 30 direction of travel 14 toothing 35 31 rotating device

Claims

1. Machine tool in which the workpiece (20) is rotatably driven by the workpiece spindle (2) of the machine (1), in particular turning, turning, milling, rotary broaching and cylindrical grinding machine, with a workpiece spindle (2) driving spindle motor (3), - with a chuck (4) non-rotatably connected to the spindle (2)

Clamping elements, in particular clamping jaws (5a, b, c), for holding the

Workpiece (20), a clamping cylinder (6) for moving the clamping elements, in particular the clamping jaws (5a, b, c), the chuck (4), characterized in that the clamping group consisting of chuck (4) and clamping cylinder (6) at least partially in the longitudinal area of the workpiece spindle (2) in its hollow interior (7) is arranged centrally.

2. Machine tool according to claim 1, characterized in that the interior (7) of the workpiece spindle (2) in the longitudinal direction (10) is accessible on both sides and open.

3. Machine tool according to one of the preceding claims, characterized in that the clamping cylinder (6) of the clamping group is arranged in the interior (7).

4. Machine tool according to one of the preceding claims, characterized in that the chuck (4) attached to the front end of the workpiece spindle (2), in particular with its back plate (11) screwed to the front end of the workpiece spindle (2) , is.

5. Machine tool according to one of the preceding claims, characterized in that the rotary distributor (8) is arranged coaxially on the rear end of the clamping cylinder (6) and is still in the interior (7) of the workpiece spindle (2).

6. Machine tool according to one of the preceding claims, characterized in that the clamping group consisting of chuck (4) and clamping cylinder (6) forms a preassembled and functionally testable unit, in which, however, the functions, namely on the one hand the movement of the clamping elements relative to the chuck (4th ) and on the other hand the movement of the clamping piston acting on the clamping elements in the clamping cylinder is realized spatially and functionally separately in the chuck (4) or clamping cylinder (6).

7. Machine tool according to one of the preceding claims, characterized in that the clamping group as a preassembled and functionally testable unit also includes the rotary distributor (8) and in particular also the supply flange (9).

8. Machine tool according to one of the preceding claims, characterized in that the rotary distributor (8) is supported radially on the circumference of the interior (7) of the workpiece spindle (2).

9. Machine tool according to one of the preceding claims, characterized in that the workpiece spindle (2) via a spindle motor (3) arranged on the spindle motor (3) is driven via a gear.

10. Machine tool according to one of the preceding claims, characterized in that the workpiece spindle (2) is part of an integrated spindle motor, in particular the rotor (22) of an integrated spindle motor (3 ') and accordingly with electrical lines (19), in particular is equipped as a winding or permanent magnet on its outer circumference.

11. Machine tool according to one of the preceding claims, characterized in that the outer diameter of the workpiece spindle (2) corresponds approximately to the outer diameter of the chuck (4), in particular at least 60%, in particular at least 80% of the outer diameter of the chuck (4).

12. Machine tool according to one of the preceding claims, characterized in that the chuck (4) and the clamping cylinder (6) adjoin one another directly in the longitudinal direction, that is to say without bridging elements such as draw tubes etc. overcoming axial length.

13. Machine tool according to one of the preceding claims, characterized in that on the headstock for mechanical displacement of components to be carried out, in particular the abutment of the clamping elements on the workpiece, reaching the front or rear end position of the clamping piston and in particular also the movement of the headstock (12) in Longitudinal direction (10) with respect to the bed (18) of the lathe position measuring systems are available.

14. Machine tool according to one of the preceding claims, characterized in that the magnetostrictive position sensor (17) comprises a magnetostrictive electrical conductor, stretched in the direction of the movement to be monitored, and a close to the magnetostrictive conductor (17a), attached to the component to be moved , Magnets (17b) and in particular positions along the Conductor (17a), when the magnet (17b) is to be used to stop the movement of the component to be moved, can be entered into the machine control by software.

15. Headstock (12) for a machine tool, in which the workpiece (20) is rotatably driven by the workpiece spindle (2) of the machine (1), d ad u rch ke n nzei ch n et, that the headstock the characteristic Features of one or more of the preceding claims.

16. A method for producing a headstock for a machine tool, in which the workpiece (20) is rotatably driven by the workpiece spindle (20) of the machine (1), and wherein the headstock - a workpiece spindle (2) which is rotatably drivable in the housing of

Headstock (12) is mounted with a chuck (4) connected to the spindle (2) in a rotationally fixed manner

Clamping elements, in particular clamping jaws (5a, b, c) for holding the

Workpiece (20) and - a clamping cylinder (6) for moving the clamping elements, in particular

Clamping jaws (5a, b, c) of the chuck (4), d ad u rch ge ke n nze i ch n et, that s the chuck (4) with the clamping cylinder (6) pre-assembled into a clamping group and functional is checked and the clamping group is inserted on the face side into the interior (7) of the workpiece spindle (2), which is particularly continuous in the longitudinal direction and is open on both sides, and is firmly connected to it.

17. The method according to claim 16, characterized in that the creation of the clamping group also includes the mounting of the rotary distributor (8) and in particular the supply flange (9) for the energy supply of the clamping cylinder (6).

18. The method according to any one of the preceding method claims, characterized in that the clamping group is connected to the workpiece spindle (2) by the back plate (11) of the chuck (4) being screwed to the front end of the workpiece spindle (2).

19. The method according to any one of the preceding method claims, characterized in that the rotary distributor (8) is supported radially on the inner circumference of the workpiece spindle (2).