METHOD AND GRINDING MACHINE FOR GRINDING EXTERNAL AND INTERNAL CONTOURS OF WORKPIECES IN ONE CLAMPING

Abstract

A method and a grinding machine to implement the method includes, in a single clamping, a machine part is ground. The part is clamped on its ends and has an internal recess for grinding. The internal recess is ground with an internal grinding wheel, wherein the part is rotated between a workpiece headstock and a tailstock, and an external contour is ground by means of a grinding wheel. The part is held on the tailstock by a hollow tailstock sleeve, on the end region of the internal recess, and the internal grinding wheel passes through the hollow tailstock sleeve during grinding. In the grinding machine, a separate grinding spindle head carrying the internal grinding wheel can be included in the region of the tailstock, and can be advanced against the peripheral surface of the internal recess by passing through the hollow tailstock sleeve and the hollow center.

Claims

1.-18. (canceled)

19. A method for the grinding, in a single clamping, of a machine part made to rotate about its longitudinal axis, clamped on both of its axial ends and having an internal recess on at least one of its ends which is ground by means of an internal grinding wheel, wherein the machine part is held rotatingly driven between a workpiece headstock and a tailstock, in a single clamping, and the external contour thereof is ground by means of at least one grinding wheel, wherein a) the machine part is held centrically on the tailstock by means of a live or rotationally driven hollow tailstock sleeve on the end region of the internal recess, b) the internal grinding wheel passes through the hollow tailstock sleeve during the grinding of the internal recess, and c) the grinding of the internal recess and the grinding of the external contour of the machine part are performed at least partially at the same time, and d) the clamping on the workpiece headstock is performed with a centrically clamping chuck or with a chuck having equalizing jaws, and a center with engages with the end face of the machine part.

20. The method according to claim 19, wherein the grinding is performed without any change in the reference axes of the clamping, and without the support of a steady rest.

21. The method according to claim 19, wherein the center is hollow, and a further internal grinding wheel passes through the same to grind a further internal recess.

22. The method according to claim 19, wherein the internal grinding wheel and the grinding wheel engage with and disengage from the machine part as a result of a single, shared grinding spindle head swiveling and/or moving in a particularly continuous manner, the same being moved by a swiveling arrangement on a carriage to grind the internal recess and to grind the external contour in a direction parallel to the longitudinal axis of the machine part.

23. The method according to claim 19, wherein the grinding wheel is arranged on a grinding spindle head, and the swiveling thereof produces the grinding engagement with the machine part.

24. The method according to claim 23, wherein the internal grinding wheel is arranged on a separate grinding spindle head in the region of the tailstock, and is moved in the direction of the longitudinal axis of the machine part to pass through the hollow tailstock sleeve.

25. The method according to claim 19, wherein, when the external contour of the machine part is ground, the rotational axis of the grinding wheel, and the longitudinal axis which runs through the workpiece headstock, the machine part, and the tailstock, are oriented at an oblique angle relative to each other in space such that the contact between the grinding wheel and the external contour of the machine part is substantially only punctiform, and the longitudinal feed is performed in the direction approaching the workpiece headstock.

26. The method according to claim 19, wherein, when the external contour of the machine part is ground, the rotational axis of the grinding wheel, and the longitudinal axis which runs through the workpiece headstock, the machine part, and the tailstock, are oriented in the plane at an angle relative to each other such that the contact between the grinding wheel and the external contour of the machine part is substantially linear in shape, as in angular plunge grinding.

27. The method according to claim 19, wherein the grinding wheel can grind both peripheral regions and end faces of the machine part.

28. The method according to claim 19, wherein the hollow tailstock sleeve is live.

29. The method according to claim 19, wherein the grinding of the machine part is controlled with CNC.

30. A grinding machine designed as a universal circular grinding machine and/or a non-circular grinding machine, to carry out the method according to claim 19, including the following features: a) a workpiece headstock and a tailstock, wherein a machine part which will be ground can be clamped between the same, are arranged on a grinding table, and the longitudinal axis running through the workpiece headstock, the machine part, and the tailstock runs in the longitudinal direction of the grinding table, b) the workpiece headstock has a centrically clamping chuck or a chuck with equalizing, releasable jaws, and a centering tip which holds and rotates the machine part on the workpiece headstock, c) the tailstock has a live or rotationally driven hollow tailstock sleeve with a hollow center, adapted to center and engage with the end of the machine part opposite the workpiece headstock, at least in a rotationally symmetric internal recess, d) the hollow tailstock sleeve with the hollow center has an internal bore through which an internal grinding wheel carried on a grinding spindle head can pass to grind the internal recess, and e) the workpiece headstock and the tailstock can move relative to each another in such a manner that the machine part is held and rotationally driven under axial pressure between the centering tip on the workpiece headstock and the hollow center on the tailstock, without any change in the reference axis of the clamping.

31. The grinding machine according to claim 30, wherein the grinding spindle head which carries the internal grinding wheel can swivel about a vertical swivel axis and is arranged on a carriage which can move perpendicular to the longitudinal direction of the grinding table in a controlled manner, and additionally accommodates a rotationally driven grinding wheel with a horizontal axis of rotation, for the grinding of the external contour of the machine part.

32. The grinding machine according to claim 30, wherein the grinding spindle head which carries the internal grinding wheel is a separate grinding spindle head in the region of the tailstock and/or in the region of the chuck which comprises a hollow center, and the internal grinding wheel can be advanced into the internal recess and against its peripheral surface.

33. The grinding machine according to claim 30, wherein the peripheral surface and the end face of the grinding wheel each have a grinding layer.

34. The grinding machine according to claim 30, wherein the internal grinding wheel and the grinding wheel each have a CBN coating.

35. The grinding machine according to claim 30, wherein the chuck is hollow and enables the passage of a further internal grinding wheel to grind a further internal recess of the machine part on the workpiece headstock end thereof.

Description

[0025] Further embodiments and details of the present invention will now be explained in detail with reference to the accompanying drawings, wherein:

[0026] FIG. 1: shows a grinding machine according to the invention, in top view;

[0027] FIG. 2: shows a grinding machine which corresponds to the basic structure in FIG. 1, but has an additional internal grinding spindle head;

[0028] FIG. 3: shows a partial view of the grinding machine according to the invention, the grinding wheel, comprising the external grinding spindle, swiveled-in for the external grinding of the machine part;

[0029] FIG. 4: shows a partial view of a grinding machine, with the grinding spindle, comprising the internal grinding wheel, swiveled-in;

[0030] FIG. 5: shows a detailed view of the machine part clamping in the workpiece headstock by the chuck, as well as the clamping by the hollow tailstock sleeve, with the internal grinding wheel out of engagement;

[0031] FIG. 6: shows a detailed view according to FIG. 5, with the internal grinding wheel in engagement with the internal recess of the machine part;

[0032] FIG. 7: shows a basic top view of a grinding machine according to the invention, with two grinding spindle heads;

[0033] FIG. 8: shows a detailed view of the grinding machine according to the invention, with two internal grinding spindles for internal recesses present on both ends of the machine part; and

[0034] FIG. 9: shows a basic arrangement of a machine part in the form of a toothed wheel, which will be ground according to the method of the invention.

[0035] The grinding machine shown in top view in FIG. 1 has a basic construction which generally accords with the construction of a universal circular grinding machine and/or non-circular grinding machine. A grinding table 28 disposed in the conventional manner has guided longitudinal movement on a machine bed 27 in the direction of a so-called Z-axis. A workpiece headstock 9, with its drive motor (not indicated) and a chuck 11, is mounted on the grinding table 28. The chuck 11 is used to clamp the workpiecethat is, the machine part 2. The machine part is clamped on the workpiece headstock 9 by means of a centering tip 13 and the releasable clamping jaws 12 of the chuck 11.

[0036] A tailstock 10 is arranged coaxially with the workpiece headstock 9 at an axial distance from the same. The tailstock 10 has a separately constructed spindle sleeve to accommodate a tailstock center designed as a hollow tailstock sleeve 15. The tailstock 10 is likewise arranged on the grinding table 28, such that the machine part 2 is clamped in the conventional manner between the workpiece headstock 9 and the tailstock 10, in the same rotary axisthe longitudinal axis 1 of the machine part 2. For process monitoring, measuring devices 23.1, 23.2 and 23.3 are included in the grinding machine. These are used to measure external- and/or internal diameters. The measurement signals obtained from the measuring devices are used for monitoring and controlling the grinding machine, wherein the measurement signals are fed directly to the controller of the grinding machine in the usual manner. As is likewise conventional, a dressing device 29 is included to dress grinding wheels used in the grinding machine. Also shown is a steady rest 22 which partially surrounds the circumference of the machine part when in active use, and which is furnished only if the machine part is comparatively long, in order to compensate for the grinding forces exerted by abrasive grinding wheels during the grinding of the external contour. A steady rest is not required in the end region of the machine part for the purpose of internal grinding, as is the case in the prior art. It is merely optional and serves only to prevent the deflection of a relatively long machine part potentially caused by grinding forces. In the case of shorter components which have sufficient bending stiffness, the steady rest can be dispensed with.

[0037] The grinding machine has a grinding spindle head 18, the same having a grinding spindle 25 with a grinding wheel 8 for internal grinding, a grinding spindle 26.1 with a first external grinding wheel 16.1, and a grinding spindle 26.2 with a second external grinding wheel 16.2. This means that the three grinding spindles 25, 26.1 and 26.2 are all arranged on the same, shared grinding spindle head 18. The grinding spindle head 18 is arranged on a carriage 19.1 in a manner which enables swiveling about a swivel axis 24. The carriage 19.1 in turn is able to slide perpendicularly to the common axis of rotationthat is, the longitudinal axis 1. The carriage 19.1 can therefore slide in the conventional X-axis. The swivel movement of the grinding spindle head 18 is indicated by the curved double arrow B. The sliding movement of the carriage 19.1 is indicated by the straight double arrow X. Z indicates the sliding movement in the direction of the longitudinal axis 1 of the machine part 2, while C indicates the rotation of the machine part about the common axis of rotationthat is, the longitudinal axis. The swiveling of the grinding spindle head 18 brings each of the grinding wheels needed for the machining processthat is, the internal grinding wheel 8, the first external grinding wheel 16.1 and/or the second external grinding wheel 16.2into engagement with the machine part 2, to execute their respective grinding tasks.

[0038] In the described embodiment according to FIG. 1, the external contour and the internal contour of the machine part 2 are ground one after the other; the arrangement of all grinding wheels with their grinding spindles on one grinding spindle head 18 means that the respective grinding tasks can only be carried out one after the other. In any case, the machine part remains in one and the same clamping with one and the same centering in the grinding machine according to the inventionspecifically for both the grinding of the external contour and the grinding of the internal contour. The first external grinding wheel 16.1 is used to grind the external contour of the machine part 2. The second external grinding wheel 16.2 can grind both rotationally symmetrical peripheral faces and end faces of the machine part 2. This ensures that end faces of the machine part 2, if present, can also be ground in the same clamping. The grinding spindle 25 carries the internal grinding wheel 8, which has a small diameter and serves to grind the rotationally symmetrical internal recess 6 of the machine part 2, in a configuration where the internal grinding wheel 8 passes through the hollow tailstock sleeve 15. Due to the small diameter of the internal grinding wheel 8, it is also called a mounted point. The method according to the invention can be carried only with the internal grinding spindle 25 with the internal grinding wheel 8, and the grinding spindle 26.2 with the external grinding wheel 16.2. The grinding spindle 26.1 also arranged on the grinding spindle head 18, with its external grinding wheel 16.1, can be utilized for further machining operations on the machine partfor example, to grind additional peripheral surfaces and end faces, or cut-ins.

[0039] A further advantage of the method according to the invention arises when the internal recess 6 is ground by means of the internal grinding wheel 8, which passes through the hollow tailstock sleeve 15. This is that the cooling lubricant is fed directly through the hollow tailstock sleeve 15 to the inner surface, of the internal recess 6, with which the internal grinding wheel 8 engages during the grinding of the internal recess 6. This makes it possible for the cooling lubricant to be fed directly to the grinding area in an optimum manner.

[0040] FIG. 2 shows a top view of a grinding machine according to the invention, in a basic illustration which substantially corresponds to the grinding machine according to FIG. 1. As such, the same reference numerals refer to the same components or elements. In contrast to FIG. 1, however, the grinding machine according to FIG. 2 has an additional internal grinding spindle head 30 in the region of the tailstock 10. This internal grinding spindle head 30 is likewise arranged on the machine bed 27 and carries a further internal grinding spindle 31 in the manner of a further, second carriage 19.2, which carries a further internal grinding wheel 32. The further internal grinding spindle 31 is able to slide on the carriage 19.2 in the Z2-directionthat is, in the direction of the longitudinal axis 1 of the machine part 2, and can therefore be inserted through the hollow tailstock sleeve 15 into the internal recess 6 for the machining of the same. In addition, the carriage 19.2 can be moved in the X2-direction, such that the feed can be adjusted according the machining operation in the internal recess.

[0041] FIG. 3 shows a detailed view of the basic construction of the grinding machine according to the invention in FIG. 1. The machine part 2 is clamped on the workpiece headstock 9 in the chuck 11, with respect to its longitudinal axis 1, between the centers by means of the clamping jaws 12 and the centering tip 13, and on the tailstock 10 by means of the hollow tailstock sleeve 15 and the live hollow center 20. This clamping between the centers is maintained throughout the machining process. The machine part 2 has, in its left half, a circumferential collar comprising the end faces which face the workpiece headstock 9 and the hollow tailstock sleeve 15. Moreover, the machine part 2 has a shoulder in the region of the clamping in the workpiece headstock 9, which also forms an end face. On the grinding spindle head 18, the swivel movement of which is indicated by curved double arrow B, the grinding spindle 26 with the external grinding wheel 16 is swiveled in the direction of the workpiece for the external grinding thereof. The entire cylindrical external contour 17 of the machine part 2 is ground by means of the external grinding wheel 16. The external grinding wheel 16 is designed in such a manner that it can also grind the end faces on the machine part 2 with its front edge. The external grinding wheel 16 is advanced over the X-axis toward the external contour 17 of the machine part 2, such that the external grinding can be performed by means of this external grinding wheel 16. The ability of the grinding spindle 26, together with its external grinding wheel 16, to slide in the Z-direction enables the grinding of the end faces of the peripheral collar, as well as the end faces of the shoulder in the region of the workpiece headstock 9. This makes it possible to grind the entire external contour of the machine part 2.

[0042] The tailstock 10 is not equipped with a conventionally designed sleeve. Rather, it has a bored-out hollow sleeve with a very short mount. A hollow center 20 is included in the bore of the hollow tailstock sleeve 15, forming the tailstock center. It engages with the end-face region of the machine part 2 in such a manner that the machine part 2 is clamped on the end facing the tailstock 10 with respect to its longitudinal axis 1, and centered with respect to the longitudinal axis 1. The hollow bore of the hollow tailstock sleeve 15 enables a grinding wheel (not shown) used for the internal grinding to pass through the hollow bore into the region of the internal recess 6 of the machine part 2, in order to perform the machining of the internal recess.

[0043] FIG. 4 shows a grinding machine in a detailed view and top view, according to the view of FIG. 1, wherein the internal recess 6 is ground on the machine part 2. The machine part 2 is again held centrically in the workpiece headstock 9 by its left end, by means of the chuck 11 and the clamping jaws 12, as well as the centering tip 13. Similarly, the machine part 2 is likewise clamped centrically, on the end 5 opposite thereto, in the tailstock 10 by means of the hollow tailstock sleeve 15 thereof, via the live hollow center 20 in the samespecifically in such a manner that the longitudinal axis 1 of the machine part 2 forms its axis of rotation. The external contour 17 of the machine part has been ground in the manner described in connection with FIG. 3. For the internal grinding of the internal recess 6, the internal grinding wheel 8 with its internal grinding spindle 25, which is mounted on the grinding spindle stock 18 and can swivel about the swivel axis 24 thereof, has been swiveled into the recess 6 of the machine part 2 through the hollow bore of the hollow tailstock sleeve 15, and brought into a machining engagement. In addition to the ability of the internal grinding spindle 25 to swivel about the swivel axis 24, the grinding spindle head 18 can be brought into a machining engagement in the internal recess along the X-axis. In addition, so as to pass through the hollow tailstock sleeve 15, the internal grinding wheel 8 can be moved in the Z-direction in such a manner that the internal grinding wheel 8 can be guided through the hollow bore of the hollow tailstock sleeve 15 into the internal recess 6 of the machine part 2.

[0044] The tailstock 10 is mounted very shortthat is, has a short construction in the axial directionand has a hollow inner bore as described. During the internal grinding, the machine part 2 remains clamped between the centers.

[0045] FIG. 5 shows, in an enlarged detail view, the machine part 2 which is centrically clamped in the chuck 11, in the jaws 12, on the longitudinal end face 14 of the machine part 2, by means of the centering tip 13. At the opposite end 5 of the machine part 2, the live hollow center 20 of the hollow tailstock sleeve 15 is used for the overall centric clamping of the machine part 2.

[0046] In contrast to the embodiments according to FIGS. 3 and 4, an embodiment is shown here in which the external contour 17 is ground by means of the external grinding wheel 16 on the grinding spindle head 18, not illustrated, whereas the internal grinding wheel 8 mounted on the internal grinding spindle 25 can be guided through the hollow bore of the hollow tailstock sleeve 15 into the internal recess 6 to grind the internal peripheral surface 7 thereof. In the position shown in FIG. 5, the internal grinding wheel 8 is in a position prior to the passage through the hollow bore of the hollow tailstock sleeve 15. The internal grinding spindle 25 with the internal grinding wheel 8 in the form of a mounted point can be advanced on a separate internal grinding spindle head (not shown) in the Z-directionthat is, in the direction of the longitudinal axis 1as well as in the X-directionthat is, in the direction toward a machining engagement with the peripheral surface 7 of the internal recess 6.

[0047] The mount of the hollow tailstock sleeve 15 is configured with high-precision spindle bearings, wherein the live hollow center 20 revolves with the machine part 2 due to the clamping forces produced by the friction in the center. The live hollow center 20 engages, either with a seal or a positive connection, with an internal surface at the opposite end 5 of the machine part 2. In principle, it would also be possible to perform the machining of the machine part 2 with a centering clamping by means of a stationary centerthat is, a non-revolving center. It would be possiblealthough this is not shown herefor the hollow tailstock sleeve 15 to be designed as a hydrodynamic or hydrostatic bearing.

[0048] The cooling lubricant is supplied on the side of the workpiece headstock 9 through the centering tip 13 of the chuck 11. This enables cooling lubricant to reliably move from the side of the workpiece headstock to the internal recess 6, for the grinding thereof, by means of the internal grinding wheel 8. However, this is only possible, of course, if the machine part 2 has a through bore. So that, during the internal grinding, sufficient cooling lubricant can be delivered in this manner to the actual machining engagement point, the internal grinding wheel 8 has a conical attachment on its front which serves to feed the cooling lubricant directly to the machining engagement. Reliable lubrication is particularly important for internal grinding because the internal grinding wheel 8 nestles into the peripheral surface 7 being ground, and the region of engagement of the grinding wheel on the peripheral surface 7 of the internal recess 6 is accordingly larger than is the case for external grinding or a cylindrical, or moreover a non-cylindrical surface.

[0049] FIG. 6 shows a view according to FIG. 5, wherein, however, the internal grinding wheel 8 has been brought through the hollow bore of the hollow tailstock sleeve 15 into the internal recess 6 of the machine part 2 and into engagement with the peripheral surface 7 thereof. The further components or elements indicated by corresponding reference numerals correspond to those of FIG. 5, and are therefore not described again in detail here.

[0050] FIG. 7 shows a further embodiment of a grinding machine according to the invention, wherein two separate grinding spindle heads 18.1, 18.2 are shown on the machine bed 27. The two grinding spindle heads 18.1, 18.2 each carry an external grinding wheel 16.1, 16.2 and an internal grinding wheel 8.1, with the corresponding internal grinding spindle 25.1, and/or 8.2, with the corresponding internal grinding spindle 15.2. The grinding spindle head 18.1 can swivel about a swivel axis B1, which is indicated by the double arrow. In an analogous manner, the grinding spindle head 18.2 can swivel about a swivel axis B2, which is likewise indicated by the double arrow. In the conventional manner, the grinding spindle heads 18.1 and 18.2 can be advanced in the X1- or X2-axis direction, as well as in the Z1- or Z2-direction, toward the longitudinal axis 1 of the machine part 2. As a result, it is possible that, for grinding the external contour of the machine part 2, the corresponding external grinding wheel 16.1 and/or 16.2 can be brought into engagement, whereas the machine part 2 with a central bore is centrically clamped both on its left end and on its opposite end 5 by means of hollow sleeves, such that the machine part 2 which has an internal recess on each of its ends can be ground internally on both ends by means of the internal grinding wheels 8.1 and 8.2. Such a configuration also enables the machine part 2, which is held in the manner described above on one end thereof in a workpiece headstock 9.1 arranged on the grinding table 28, but which is designed with a hollow chuck, and is held on the opposite end 5 in a hollow tailstock sleeve 15, to be held by means of respective hollow centers 20.1 and 20.2 (see FIG. 8) in such a manner that the left side internal recess and the right side internal recess can be ground at least partially at the same time. However, it is also possible with this configuration to grind the respective internal recess at least partially at the same time as the grinding of the external contour by means of either the first external grinding wheel 16.1 or the second external grinding wheel 16.2, using an internal grinding wheel arranged on the other grinding spindle head. It is also possible to perform the grinding, at least partially at the same time, using both of the external grinding wheels 16.1 and 16.2, specifically to grind the external contour using one of the two grinding wheels while the other of the two grinding wheels grinds the end faces. Such an arrangement therefore further increases the flexibility of the grinding machine according to the invention, although the equipment costs are higher. Such an arrangement can achieve a reduced cycle time despite complex contours of the machine parts being ground. The workpiece headstock 9.1 is driven by means of a drive motor 33 which is arranged with a housing axially parallel to the longitudinal axis 1 of the machine part 2. The tailstock 10 can slide in the Z-direction, but is not driven.

[0051] FIG. 8 shows the basic arrangement of FIG. 7, in an enlarged illustration. However, only the internal grinding wheel 8.2, with the corresponding internal grinding spindle 25.2, and the internal grinding wheel 8.1, with the corresponding internal grinding spindle 25.1, are ready for insertion through the respective hollow bores of the workpiece headstock 9.1 and/or tailstock 10. The mount and drive of the workpiece headstock 9.1 are illustrated on the left end of the centrically clamped machine part 2. To drive the centering tip 20.1 or the chuck, the drive motor 33 implemented via beltsparticularly toothed beltsis included, in addition to the mount of this hollow workpiece headstock 9.1 with its short construction. The possible, at least partially simultaneous machining of the external and internal contours of the machine part 2 is carried out in the sequence and manner described above in connection with the other figures

[0052] And finally, FIG. 9 shows a simplified illustrated embodiment for grinding a machine part 2, which, unlike in FIGS. 1 to 8, is not a shaft component, but rather a toothed wheel component. For simplicity, the corresponding grinding spindle heads are not shown. The centered clamping of this toothed wheel component is performed by the chuck 11 clamping the toothed wheel with its clamping jaws 12 on the outer toothing thereof. To achieve a precise alignment, end face stops are included on the chuck 11, and the toothed wheel is clamped against the same. This achieves an unambiguous orientation of the reference axisnamely the longitudinal axis 1 of the toothed wheel 2which is fixed for the entire operation. Profiled external sections in the hub region of the toothed wheel are ground by means of a profiled external grinding wheel 16.1 which is mounted for driven rotation on a corresponding grinding spindle 26.1. Furthermore, an internal grinding wheel 8 is included, which is rotatably driven on the corresponding internal grinding spindle 21, and which can be inserted on a separate grinding spindle head into the hub boring via the Z3-axis, such that the hub bore can be ground at least partially at the same time as the external contour via an advancement along the X3-axis. An additional grinding spindle head (not shown) is included on the side of the chuck 11, and carries a grinding wheel 16.2 with associated spindle 26.2. The external grinding wheel 16.2 is a profiled grinding wheel and is used to grind the end faces on the collar and/or on the hub of the toothed wheel 2. Likewise, both the external contour and the internal contour of this toothed wheel can be ground according to the invention at least partially at the same time.

LIST OF REFERENCE NUMBERS

[0053] 1 longitudinal axis [0054] 2 machine part [0055] 3 axial end [0056] 4 bearing pin [0057] 5 opposite end [0058] 6 internal recess [0059] 6.1 further internal recess [0060] 7 peripheral surface [0061] 8 internal grinding wheel [0062] 8.1 first internal grinding wheel [0063] 8.2 second internal grinding wheel [0064] 9 workpiece headstock [0065] 9.1 workpiece headstock with hollow sleeve [0066] 10 tailstock [0067] 11 chuck [0068] 12 jaws [0069] 13 centering tip [0070] 14 end face [0071] 15 hollow tailstock sleeve [0072] 16 external grinding wheel [0073] 16.1 first external grinding wheel [0074] 16.2 second external grinding wheel [0075] 17 external contour [0076] 18 grinding spindle head [0077] 18.1 first grinding spindle head [0078] 18.2 second grinding spindle head [0079] 19.1 first carriage [0080] 19.2 second carriage [0081] 20 live hollow center [0082] 20.1 workpiece headstock hollow center [0083] 20.2 tailstock hollow center [0084] 22 steady rest [0085] 23.1 first measuring device [0086] 23.2 second measuring device [0087] 23.3 third measuring device [0088] 24 swivel axis [0089] 25 grinding spindle internal grinding wheel [0090] 25.1 first internal grinding spindle [0091] 25.2 second internal grinding spindle [0092] 26 grinding spindle of the external grinding wheel [0093] 26.1 grinding spindle of the first external grinding wheel [0094] 26.2 grinding spindle of the second external grinding wheel [0095] 27 machine bed [0096] 28 grinding table [0097] 29 dressing device [0098] 30 additional internal grinding spindle head [0099] 31 further internal grinding spindle [0100] 32 further internal grinding wheel [0101] 33 drive/drive motor