EP1330338A1

EP1330338A1 - Multi-purpose machine

Info

Publication number: EP1330338A1
Application number: EP01978451A
Authority: EP
Inventors: Anton Horsky; Paul Dieter Scharpf; Wolf-Dietrich Voss
Original assignee: Boehringer Werkzeugmaschinen GmbH
Current assignee: MAG IAS GmbH Eislingen
Priority date: 2000-10-23
Filing date: 2001-10-23
Publication date: 2003-07-30
Anticipated expiration: 2021-10-23
Also published as: DE50103668D1; WO2002034466A1; US6926591B2; DE10052443A1; JP2004512185A; US20040023600A1; ATE276070T1; EP1330338B1

Abstract

The invention concerns a method and an apparatus in which crankshafts and similar components can be machined at the relevant machining locations (big-end bearing locations, main bearing locations, side cheek side surfaces, end journal/end flange) on one machine and thus with a low level of expenditure in terms of investment items and nonetheless overall in highly time-efficient manner, by mechanical material removal in one and the same machine, wherein in all machining steps the workpiece is gripped on the central axis and is drivable in rotation and the concentric rotationally symmetrical surfaces are machined by workpiece-based methods.

Description

Combination machine

I. Field of application

The invention relates to the machining of workpieces by means of material-removing, preferably mechanical, material-removing methods and devices in this regard, the workpieces comprising rotationally symmetrical surfaces which are arranged both centrally and eccentrically with respect to the central axis of the workpiece and, if appropriate, furthermore end surfaces which are to be machined.

II. Technical background

A typical workpiece of this type is crankshafts, in which the outer surfaces of the main bearings represent the central rotationally symmetrical surfaces and the outer surfaces of the pin bearings represent the eccentric rotationally symmetrical surfaces. In addition, the machining of the end pegs or end flanges (small or large outer diameter), which represent the end region and thus the end region and therefore the region used for clamping in chucks, pose a difficulty, and the machining of cheek side surfaces associated with the decrease in large amounts of material.

Crankshafts are typical representatives of workpieces that combine the following problems: Both centrally and eccentrically positioned, rotationally symmetrical workpiece surfaces must be machined,

end faces must also be machined,

the end areas of the workpiece, on which the clamping in the machine chucks normally takes place, must also be machined, and these must correspond to a high degree with regard to roundness and center alignment with the other areas of the workpiece,

Due to its geometry, the workpiece is not very resistant to machining forces, especially those applied radially.

The well-known range of material-removing machining processes is available for machining the individual surfaces, starting with the machining processes whose tools have a geometrically defined cutting edge. These methods can be divided into the following two groups:

- Workpiece-based processes, i.e. processes in which the desired cutting speed (relative speed between the workpiece surface and the cutting edge of the tool working on it) is primarily achieved by the speed of rotation of the workpiece: longitudinal turning, facing turning, broaching, turning broaching (the broaching blades are on the circumference of a arranged round tool body, which rotates during machining, but slower than the workpiece), turning-broaching (in addition to the above-mentioned turning broaching, there are also turning tools on the tool base body, when using the turning broaching tool does not rotate, but linearly in X - or Z direction with respect to the workpiece for longitudinal or face turning), finish

(Grinding with essentially stationary finishing tool; even finer grit than grinding tools) and Tool-based processes, in which the cutting speed is primarily achieved through the movement, especially rotation, of the tool: Orthogonal milling (a milling tool that is perpendicular to the rotationally symmetrical surface with its axis of rotation, it primarily works with that on the End face of the milling cutter available

Face cutting), external milling (a disc-shaped milling cutter, whose axis of rotation lies parallel to the axis of rotation of the workpiece, works primarily with the corresponding outer surface of the workpiece with the cutting edges arranged on its outer circumference), external cylindrical grinding (instead of the disc-shaped milling tool described above, a disc-shaped grinding disc is positioned in the same position as the workpiece ) are used.

The last-mentioned representatives in both groups are already processes with a geometrically undefined cutting edge.

There are also processes that remove material without a mechanical cutting edge, for example electro-erosion processes, material removal using a laser, etc., which, however, only require low relative speeds between the tool and the workpiece, and this relative speed either by moving the workpiece and / or the tool Can be made available.

For the large-scale production of such workpieces such as car crankshafts, the shortest possible machining time - including set-up and dead times - per crankshaft on the one hand and low tool and energy costs on the other hand are the decisive parameters, depending on the surface qualities that can be achieved (roundness, roughness depth, etc.) .), which may necessitate subsequent finishing steps such as grinding and / or finishing.

In this sense, the machining processes that remove by means of mechanical cutting edges are still preferred for large series production. With regard to the centric, rotationally symmetrical surfaces, the focus is currently on machining by means of rotary rooms or rotary rotary rooms. With regard to the eccentric, rotationally symmetrical surfaces, that is to say, for example, the hub bearing locations, external round milling is currently preferred. Since the lifting bearing point rotates around the central axis of the workpiece during machining - so that all circumferential points can be machined from one side - it is also necessary to track the corresponding tool very precisely in terms of time and geometry. In order to achieve this, tool-based methods are preferred for machining these eccentric rotationally symmetrical surfaces. If workpiece-based processes were used - to achieve a high cutting speed and thus efficient machining - the workpiece would rotate so quickly that it would not be possible to track the tool, or the speeds of the workpiece that could be achieved and thus the cutting speeds would not be competitive.

The currently preferred methods are usually used in successive series production on separate machines. In addition - usually also on a separate machine or station on a production line - the end areas, in the case of a crankshaft thus end journal and end flange, are pre-machined separately at least on the circumference, possibly also on the end face, in order to define defined clamping surfaces for further processing to have available.

For the purposes of the present application, the surface areas to be machined are only referred to as rotationally symmetrical surfaces, since this is by far the largest proportion of machining cases. Of course, non-rotationally symmetrical, but convexly curved outer round surfaces, such as the cams of camshafts, can also be machined analogously.

Occasionally it has already been considered, for small quantities, such as pre-series models of crankshafts, etc., the machining of the centric, rotationally symmetrical surfaces by means of workpiece-based machining processes and perform the machining of the eccentric, rotationally symmetrical surfaces by tool-based machining processes on one machine, in which the two corresponding tool units are both present. The extremely different speed ranges of the workpiece drive to be realized represented the one main problem, and the machining of the end areas of the crankshaft the other main problem.

II. Presentation of the invention

a) Technical task

It is therefore the object according to the present invention to provide a method and a device in which crankshafts and similar parts at the relevant processing points (hub bearings, main bearing points, cheek side surfaces, end journals / end flange) on a machine and thus with little effort Capital goods, but can still be processed very efficiently.

b) solving the problem

This object is solved by the features of claims 1 and 13. Advantageous embodiments result from the subclaims.

The workpiece is to be clamped on the central axis in all machining steps and driven in rotation about this axis in order to avoid the use of mechanically very complex and expensive so-called cycle chucks, which additionally severely restrict the flexibility of a machine, since they depend on the dimensions of the machining crankshaft must be turned off. Through the use of workpiece-based processes for the central surfaces, a very short machining time with a very good surface quality is achieved.

By using the tool-based machining processes on eccentric surfaces, the speed of the workpiece can be kept so low that optimum tool tracking and thus optimal dimensional accuracy of these surfaces is ensured.

In order to be able to achieve the maximum cutting speeds that can be achieved with the workpiece-based processes on the one hand and tool-based processes on the other hand, the workpiece, which is mounted in spindles in its end areas and can be driven in rotation by means of chucks, can be selected from the two sides using different drives driven, whereby one drive provides the highest possible speeds for the workpiece-based machining processes, which on the other hand only require low torques, while the other drive only has to apply the low necessary workpiece speeds for tool-based machining processes, but with high torque and compliance with defined Rotational position of the workpiece, thus also a possibility of positioning the rotational position of the workpiece with respect to this spindle. Accordingly, this slow drive is preferably also with a self-locking, realized by means of z. B. worm / worm gear ratio. Both drives can be driven by separate motors (preferred) or a common motor, but at least the self-locking slow drive train should be used. B. between the spindle and the self-locking point or between the chuck and spindle.

In order to also be able to machine the end pin and end flange, at least their outer surfaces, the spindles must have a centering tip in addition to a conventional chuck, such as a three-jaw chuck, with centering tip and the jaws of the jaw chuck relative to one another in the axial direction (Z direction) are movable, for example by using chucks retractable jaws. In this way, it is possible to connect one end region in a rotationally fixed manner to the respective spindle by means of chucking, while the other end region to be machined is supported only by a centering tip.

The end area accommodated in the slow spindle can - due to the drive by the fast spindle - be operated at high speeds and thus with the workpiece-based machining method also used for the central bearings, e.g. B. turn-turn rooms are edited.

Limitations with regard to efficiency are only necessary in the reverse case, i.e. when machining the end area accommodated in the fast spindle, usually the end flange: This is only held by a centering tip when machining, while the workpiece is held on the opposite side by the jaw chuck slow spindle is rotated.

Due to the slow speed of the workpiece, there are only two realistic machining options available:

Either machining using one of the workpiece-based methods, due to the low workpiece speed but at a very low cutting speed, with the corresponding restriction to suitable cutting materials. When turning, for example, this is high-speed steel (HSS).

Since the other surfaces machined using tool-based processes, such as the center bearings, are machined using tools made of hard metal, cutting ceramics and similar high-performance materials, even when turning, such HSS cutting edges must be additionally prepared on the corresponding tool body simply because of this end flange machining - will be.

Cuts made of hard metal or cutting ceramic would be damaged too quickly at these low workpiece speeds. The other option is to machine this end area analogously to the low workpiece speed using tool-based methods, for example using external round milling. The disadvantage here is the slightly poorer achievable surface quality compared to workpiece-based methods. Since generally the same minimum surface quality requirements are set for all workpiece surfaces of the same type, for example all central bearing points, this end flange machining may not achieve a quality requirement that can be achieved for all other center bearing points due to the more suitable machining process.

Since, when machining at least one of the end areas (end pin / end flange), a clamping by means of chuck is generally necessary first on the unprocessed outer circumference of the workpiece, at least this corresponding chuck must have compensating clamping jaws. Likewise, a rotational position fixation of the workpiece relative to one of the spindles must be present on one of the spindles, for example a rotational position stop or straightening jaws in the corresponding jaw chuck.

Since, as described above, such methods and machines are used primarily for the production of crankshafts or similar workpieces in small quantities, often only in individual pieces, the external round milling cutters are chosen to be relatively narrow, so that they can be used for all crankshafts to be produced. Correspondingly, however - after machining a first axial area on a pin bearing using external round milling - the milling cutter must be axially moved - be it continuously or step by step - until the entire width of the bearing has been machined.

For this purpose, on the one hand, the milling cutter must be movable in the Z direction, i.e. the tool support must have a Z slide, and on the other hand, the cutting edges of the milling cutter must not only be present on its outer circumference, but also in the outer edge area of the end face to be able to cut on the end face with continuous infeed in the Z direction. Otherwise, only axial section-by-section machining via grooving and circumferential machining is possible.

If only the processing of individual pieces is intended or the processing time only plays a very subordinate role, it can be deviated from the above-mentioned solution in that the eccentric rotationally symmetrical surfaces and despite the drive during their processing via the slow spindle drive with a workpiece-based processing method such as turning. As previously described with regard to the machining of the end area that is accommodated in the fast spindle chuck, but can only be driven slowly, this increases the machining time for the pin bearings and thus the crankshaft very much and in addition suitable cutting materials such as HSS cutters must be available for this low cutting speed ,

The advantage of such a solution, however, in terms of machine technology, is that the same machining process is used for lifting and main bearings, albeit at very different cutting speeds, and consequently with the need for different cutting materials. These cutting edges, which consist of different materials, can either consist of two separate tool units, as described above, namely eg. B. cutting from ceramic cutting materials on one tool body and HSS cutting on the other tool body. However, both tool systems require the same movement options (in addition to moving in the X and Z direction, either swiveling around the C2 axis or moving in the Y direction) and can therefore be constructed identically and equipped with an identical control, which means the costs lowers.

Could take a step further - since the workpiece-based processes are only machining processes that do

Tool does not necessarily have to rotate a full 360 ° - cutting from both

Types of cutting material simultaneously on the same, for example disk-shaped, Tool base body may be arranged so that only a single tool unit would be necessary on the machine.

The above-mentioned high and low workpiece speeds or cutting speeds or torques when driving the workpiece are to be understood as roughly the following value ranges:

High workpiece speeds from 40 rpm to 1,600 rpm, in particular from 200 rpm to 800 rpm, low workpiece speeds from 0 rpm to 40 rpm, in particular from 20 rpm to 40 rpm, high torques of the workpiece drive from 600 Nm to 3,000 Nm, in particular from 2,000 Nm to 2,500 Nm, low torques of the workpiece drive from 200 Nm to 600 Nm, in particular from 300 Nm to 550m, cutting speeds from 150 m / s to 700 m / s, in particular from 180 m / s to 250 m / s.

The undercuts on the edge of the bearing point which are often necessary in crankshaft bearing points represent a detailed problem, which are easy to produce in central bearing points by turning, but cannot be produced when machining the pin bearings using a tool-based method. In this case, after machining the outer surface of such a pin bearing, the corresponding undercuts must be made by turning. Since the hub bearing point rotates eccentrically around the central axis of the workpiece, this rotary cutting edge must be tracked in the rotation of the workpiece, and because of this, the workpiece can only be driven at the low speed. Accordingly, cutting agents made of suitable cutting materials, such as HSS, are again necessary.

c) working examples

An embodiment according to the invention is described in more detail below by way of example. Show it 1a: a machine according to the invention in front view,

1b: another machine according to the invention in front view,

2a: the machine according to FIG. 1a in a side view from the left,

2b: another design of the machine in side view,

3a: the left spindle area of the machine according to FIG. 1a in an enlarged partial section,

3b: the right spindle area of the machine according to FIG. 1a in an enlarged partial section,

4: basic diagrams with left-hand drive of the workpiece,

Figures 5: basic representations with right-hand drive of the workpiece, and

6 shows a section along the line VI-VI of FIG. 1.

Fig. 1a shows a machine tool that a workpiece, for example the crankshaft 1 shown, which both central surfaces 2, z. B. main bearing points, as well as eccentric surfaces 3, for example hub bearing points, rotatably drivable at the end regions and processed.

The axial end region of the workpiece is accommodated in the holding devices of two mutually directed, mutually aligned spindles 15, 16. Both jaw chucks 20 and 21 and centering tips 22, 23, which are arranged on each of the spindles 15, 16, serve as receiving devices. The spindles 15, 16 are arranged on the bed 14 of the machine, as are the tool supports 12, 13, each of which carries a tool unit which can be driven to rotate about an axis parallel to the axis of rotation (Z axis) of the workpiece (C2 axis) is.

In addition, the tool supports 12, 13 can be moved in a defined manner in the X direction, that is to say transversely to the axial Z direction, on the respective Z slide 26, 27 which can be moved in the Z direction. The Z slide is along the Z guides 33 traversable. The tool units are generally disk-shaped tool base bodies, the tool base body 18 of the one tool support 12 in the outer circumferential region being equipped with cutting edges which can be used for a workpiece-based method, for example with rotary cutting edges or rotary rotary cutting edges.

Correspondingly, this tool base body 18 does not necessarily have to be able to be rotated in a defined manner over a full 360 °, but pivoting through smaller angular ranges around the C2 axis is sufficient. However, taking a defined rotational position of the tool base body 18 is necessary. Correspondingly, this basic tool body 18 is shown when machining a central, rotationally symmetrical surface 2, namely a central bearing.

In contrast to this, the other basic tool body 19 is equipped with cutting edges of a tool-based method, for example with milling cutting edges, in its outer circumferential area, which are accordingly preferably distributed over the entire circumference of the disk-shaped basic body 19, in particular evenly distributed. The tool body 19 of this tool-based method must accordingly be able to be driven over more than 360 °, in particular over any number of revolutions.

The Z guides 33 are so long that both tool base bodies 18, 19 can reach any axial position on the workpiece in the Z direction, in particular also the end regions, namely the end pin 5 shown in FIG. 1a on the right end of the crankshaft and the one on the left End of crankshaft 1 shown end flange 6, which has a larger outer diameter than the end pin 5.

As is shown in particular by the enlarged detailed illustration of the left holding area of FIG. 1a, the crankshaft is preferably at both ends in the respective jaw chucks 20, 21 during processing, that is to say with the aid of radially gripping clamping jaws 20a, 20b, ..., 21a, 21b, ... held and driven in rotation.

Only if the circumferential areas necessary for the attachment of the clamping jaws and the end faces of the crankshaft are machined, the tension on the respective side is released by means of clamping jaws, and the crankshaft on this side is held in a corresponding centering bore of the crankshaft exclusively by means of a centering tip 22, 23 , At the same time, the clamping jaws on this side are axially retracted in the Z direction with respect to the centering tip. B. 5a or the peripheral surface of the end flange or end pin can work.

The entire headstock, in which one of the spindles, for. B. the spindle 16 is mounted, in the Z direction relative to the bed 14 of the machine can be moved in a defined manner. This enables workpieces of different lengths to be machined and also makes it easier to load and unload the machine with workpieces. It is not critical whether the jaws of a jaw chuck are movable in the Z direction in relation to the centering tip arranged on the same spindle, or the centering tip is relative to the chuck or the spindle, but in practice the shift of the Centering tip 22, 23 in the Z direction is preferred over the associated jaw chuck and the assigned spindle, as is shown separately for example in FIGS. 3a, 3b for the left and right side of the machine. It is also irrelevant whether, in the case of tension in the jaw chuck on the same side, the tension is additionally maintained by the centering tip on the same side. 1b shows a machine tool which differs from the solution according to FIG. 1a in that the tool support 13 with the associated tool base body 19, which carries the cutting edges for the tool-based method or methods, is missing.

FIG. 2a shows the machine according to FIG. 1a from the left side in a section along the line III-III. It can be seen that the headstock carrying the spindle 16 rests movable over the trough of a trough-shaped bed 14 in the Z direction. The tool support 13, which is rotatably drivable and which is designed as an X slide, is in turn guided on a Z slide in the X direction, the X direction being directed obliquely downward at an angle of 60-80 ° the horizontal is inclined.

The guide plane of the Z-slide 27 relative to the bed 14 is also not horizontal or vertical, but inclined at an angle of approximately 40-50 ° with respect to the horizontal.

2b, on the other hand, shows a bed construction with a bed 14 ', which is symmetrical with respect to the Z direction, that is to say it carries a Z-slide 26', 27 'on two oppositely arranged guide surfaces, each of which in turn has one in X1 or X2 direction, which strive apart in a V-shape upwards, carry movable tool support 12 ', 13' with corresponding tool base bodies 18 ', 19'.

Figures 3a and 3b show the left and right headstock of the machine.

The respective spindle 15 or 16 is rotatably mounted in the headstock, not specified, and is axially fixed. The jaw chuck 20 or 21 with the clamping jaws 20a, ..., 21a, ... sits on the front end of the spindle and is connected to it in a rotationally fixed manner. Both the spindle 15 and 16 as well as the jaw chuck 20 and 21 are hollow throughout in the center in the Z direction, and in this cavity the centering tip 22 and 23 is mounted, which also comes forward from the jaw chuck 20 and 21 can be positioned above.

The centering tip is rotatably mounted in relation to the spindle and jaw chuck and can be moved in the axial position.

As will still be explained with reference to FIGS. 4 and 5, it may be necessary for the machining to be able to fix the Z position of the centering tip 22, 23 in spite of being freely rotatable about the Z axis. In the solutions according to FIGS. 3a, 3b, this is solved by means of a centering stop 34 or 35, which can be moved in the Z direction inside the spindle 15, in particular with respect to the inside diameter of the spindle 15, and which is provided with an undercut the rear end of the centering tip 22, 23 is connected and thus the centering tip can both push and pull. A relative rotatability between the centering tip 22, 23 and the centering stop 34, 35 must be provided.

In Fig. 3a - as in Figures 1 - the workpiece, namely the crankshaft 1, is shown with the end flange 6 at the left end and the end pin 5 at the right end.

The crankshaft 1 is held on the left-hand side by the clamping jaws 20a, 20b,... Of the jaw chuck 20 abutting and tensioning the outer circumference of the end flange 6, the centering tip 22 additionally engaging in the corresponding centering bore 36. On the right hand side, however, the crankshaft is held exclusively by means of the centering tip 23 which engages in the centering bore 37 and which accordingly protrudes further relative to the associated jaws 21a, 21b, ... of the jaw chuck 21.

Here, too, the Z position of the centering tip 23 is analogous to the other centering tip 22 by means of a centering stop 35 which can be fixed in the axial position fixed by z. B. the thread between the centering stop 34/35 and the surrounding spindle 15, 16 is self-locking.

The two spindle sides also differ fundamentally with regard to the mutual drives:

One, for example the left, spindle 15 can be driven at high speeds by means of a motor M which is mounted on the headstock and, for example via a belt drive and related pulleys 28, 29, drives the spindle 15 in rotation about the Z axis.

The other, e.g. B. right hand, spindle 16, on the other hand, can be driven slowly by means of a further motor, not shown, via a gear pair by the worm wheel 38 being connected in a rotationally fixed manner to the spindle 16, while the motor, not shown, drives the worm 39. This drive train can be uncoupled, for example by disengaging the worm 39 and worm wheel 38, or by disengaging a clutch (not shown) in this drive train.

Figures 4 and 5 show typical clamping situations of the workpiece, for example a crankshaft 1, when machining the different areas of the workpiece.

Since the machine / method according to the invention is not designed for the highest possible machining efficiency, but rather for complete machining of centric, eccentric and end faces on the same machine, z. For crankshafts, for example, the end areas of the crankshaft are preferably also machined in order to largely avoid pre-machining - except for the introduction of centering holes for the centering tips. In this case, the peripheral surfaces of the end flange 6 and the end pin 5, on which the jaws of the jaw chuck are to engage, are preferably processed first, and - if necessary and desired - the respective end faces 5a and 6a, respectively. When machining the end regions of a workpiece, the end region to be machined is preferably held exclusively by means of a centering tip, while the drive takes place from the other end of the workpiece via the spindle there, in order to make the corresponding tool in the end region accessible at all.

FIGS. 4a-4d show situations in which the crankshaft at the left end by means of the jaws 20a, 20b,... Of the jaw chuck 20 on the circumference of the left end region, that is to say, for example. B. the end flange 6 there, clamped and driven in rotation. In the solution according to FIGS. 3a, 3b, this is the quickly drivable spindle 15.

The other, right-hand end, of the workpiece must be freely rotatable, since a synchronous drive with a likewise high speed is not possible by means of the slow rotary drive of the right spindle 16 provided on the right side.

This is achieved in that, as shown in FIGS. 4a-4d, the right end of the workpiece is held by only the right centering tip 23 being seated in the corresponding right centering hole 37 of the workpiece, and the right centering spindle 23 opposite the right workpiece spindle 16 and the right drive train is freely rotatable.

The other possibility is to clamp the right end, i.e. the slow spindle drive, of the crankshaft in the jaw chuck there, but to decouple the drive train of the right chuck, for example by disengaging the worm 39 from the worm wheel 38 of the drive train, as in Fig 4e shown.

Due to the tensions according to FIG. 4, the workpiece can be driven at high speed and thus all the central machining surfaces on the workpiece by means of a machining method on the workpiece such as Turning, turning rooms or turning-turning rooms can be edited. This also includes the end pin 5 arranged on the right side and its end surface 5a, which can be machined up to close to the right centering tip 23 in engagement.

The workpiece must also be in a defined Z position.

According to FIG. 4a, the right centering tip together with the workpiece can be pushed to the left until the right centering tip 23 reaches a centering stop 35 ', for example in the form of the centering stop 35 shown in FIG. 3. In this case, the force F2 acting from right to left, with which the right centering tip 23 is acted upon, is greater than the opposing force F1, with which the left centering tip 22 is acted upon.

The same applies in the case of FIG. 4d, but there is a workpiece stop 45 'in the area of the left chuck, through which the workpiece with the left end face 6a is pressed against this workpiece stop 45'.

If, on the other hand, the force F1 with which the left centering tip 22 is acted upon is greater than the right-to-left force of the right centering tip 23, a timely workpiece stop 44 ′ must be present in the area of the right spindle 16 according to FIG. 4b. At the same time, the right centering tip 23 must remain axially fixed in the right centering hole 37 of the workpiece, that is, the Z position of the right centering tip 23 must be fixable without impeding the rotatability of the centering tip.

Fig. 4c differs from the solution according to Fig. 4b in that - with the same relation of left to right force of the two centering tips - the left centering tip, which is acted upon by the higher force, presses against a longitudinal centering stop 34 '. This must also happen - as in the solution according to FIG. 4b - before the jaws 20a, 20b of the left jaw chuck 20 are closed. 5 shows the drive of the crankshaft from the right side, that is to say via the slow drive train. 5, the right end, for example the end pin 5, of the crankshaft 1 is clamped on the circumference of the jaws 21a, 21b of the right jaw chuck 21, which can be driven slowly rotating by the associated spindle 16.

With this type of drive, the eccentric surfaces, lateral surfaces as well as end surfaces, of the workpiece are machined using a tool-based method, the tool having to be adjusted in the X direction, as explained with reference to FIG. 6. The opposite left end of the workpiece - according to FIGS. 5a and 5b - is also received between the jaws 20a, 20b, ... of the jaw chuck 20 there, since the drive train on the left side is not self-locking and from the right drive train below Conveying the workpiece spinning empty with driven. This does not in any way lead to undesired torsion of the workpiece, but rather the drive train on the left-hand side, idling, which is idling, rather serves to dynamically damp the workpiece during machining. This is advantageous because the tool-based methods used here, such as milling, place a greater dynamic load on the workpiece than the tool-based methods because of the interrupted cut.

In addition, the left centering tip 22 can remain in engagement on the workpiece on the left side.

It is also possible to pick up the left side of the workpiece exclusively by means of the left-hand centering tip 22.

In order to hold the workpiece in a defined Z position here, too, either (Fig. 5a) the right centering tip 23 can be moved against a centering stop 35 'on the right, which then - analogous to Fig. 4a - by means of the right centering tip from the right force acting to the left in the workpiece F2 must be greater than the counteracting force of the left centering point F1 or the left chuck.

The other possibility according to FIG. 5b is to select the force F1 acting on the crankshaft from left to right by means of the left centering tip 22 or the left jaw chuck 20 in the Z direction than the opposing force F2 and the workpiece thereby against one press workpiece stop 44 'on the right.

5c - the workpiece can also be held on the left only by the centering tip, so that the jaws of the chuck are lifted off the workpiece there.

6 shows the machining of a crank bearing H1 of the crankshaft, which is tensioned and driven in rotation on the central bearing ML. From this it can be seen that when the crankshaft is rotated about the Z direction, the displacement of the crank pin H1 to be machined in the X direction must be compensated for by corresponding tracking of the machining tool, for example the rotating tool base body 18, to the same extent in the analog direction. From this it also becomes clear that the diameter of the tool base body must be selected large enough to ensure machining at the most distant position of such an eccentric workpiece surface from the axis of rotation C2 of the tool base body.

6 also shows the reception of the end pin 5 between the jaws 21a, 21b, 21c of the jaw chuck 21, and the fixing of the rotational position of the crankshaft relative to the jaw chuck by a tappet 31 off-center and transversely to the Z direction against one of the other pin bearings, z. B. H3, presses to press this against a rotational stop 32, rotational stop 32 and plunger 31 are rotatably connected to the chuck or the spindle. LIST OF REFERENCE NUMBERS

1 crankshaft 21 jaw

2 central surface 22 centering tip

3 eccentric surface 30 23 centering tip

4 cheek surface 24 longitudinal stop

5 end pins 25 rip fence

5a end face 26 Z-slide

6 end flange 27 Z-slide

6a end face 35 28 pulley

7 pin bearings 29 pulley

8 main bearings 30 end piece

10 Z direction (axial direction) 31 plunger

11 Machine 32 rotary position stop

12 Tool support 40 33 Z guides

13 Tool support 34 Centering stop

14 bed 35 centering stop

15 spindles 36 center hole

16 spindles 37 center hole

17 Motor 45 38 worm wheel

18 basic tool body 39 screw

19 Tool body 44 'workpiece stop

20 jaw chuck 45 ^* workpiece stop

20a, 20b cheek

Claims

1. A method for processing both the central (2) and the eccentric, rotationally symmetrical surfaces (3) of workpieces, in particular crankshafts (1), by mechanical material removal in one and the same machine (11), characterized in that the workpiece at all machining steps are clamped on the central axis and can be driven in rotation, the centric, rotationally symmetrical surfaces (2) can be machined by workpiece-based methods.

2. The method according to claim 1, characterized in that when machining the eccentric, rotationally symmetrical surfaces (3) the machining is carried out by tool-based methods.

3. The method according to any one of the preceding claims, characterized in that the eccentric, rotationally symmetrical workpiece surfaces (3) are processed by means of workpiece-based methods, but at at least a factor of 10 lower speeds of the workpiece than when using tool-based methods.

4. The method according to any one of the preceding claims, characterized in that the workpiece can be driven from one end at high speeds and from the other end can be driven at low speeds and compliance with defined rotational positions.

5. The method according to any one of the preceding claims, characterized in that the end pins of the workpiece are also machined.

6. The method according to any one of the preceding claims, characterized in that during the processing of the end pieces, one end piece occurs at high speed of the workpiece and by means of a workpiece-based method and the other end piece at at least a factor 10 lower speed of the workpiece by means of a drive from the end of the workpiece that can be driven at low speed.

7. The method according to any one of the preceding claims, characterized in that the one end piece is an end pin and the other end piece is an end flange with a substantially larger outer diameter than the end pin, in particular in the case of a crankshaft (1) as a workpiece, and the workpiece from the side, in particular the end flange (6) ago, can be driven at high speed.

8. The method according to any one of the preceding claims, characterized in that the machining of the end pieces takes place as early as possible, in particular before the other centric rotationally symmetrical surfaces, and from the machining of the end pieces, the peripheral surface of at least one of the end pieces for tensioning and / or driving, in particular by means of Jaw chuck, is used.

9. The method according to any one of the preceding claims, characterized in that the eccentric rotationally symmetrical surfaces (3), in particular the pin bearings (7) of a crankshaft (1) in front of the centric rotationally symmetrical surfaces (2) - except for the end regions -, in particular the main bearings ( 8) a crankshaft 1 is carried out.

10. The method according to any one of the preceding claims, characterized in that the high speeds of the workpiece during processing speeds from 40 rpm to 1,600 rpm, in particular from 200 rpm to 800 rpm, and low speeds of the Workpiece from 0 U / min to 40 U / min, in particular from 20 U / min to 40 U / min.

11. The method according to any one of the preceding claims, characterized in that the high drive torque for the workpiece during processing drive torques from 600 N xm to 3,000 N xm, in particular from 2,000 N xm to 2,500 N xm, and the low Drive torque for the workpiece Drive torques from 200 N xm to 600 N xm, in particular from 300 N xm to 550 N x m.

12. The method according to any one of the preceding claims, characterized in that the cutting speeds are in the range from 150 m / s to 700 m / s, in particular from 180 m / s to 250 m / s.

13. Machine (11) for processing both the central (2) and the eccentric, rotationally symmetrical surfaces (3) of workpieces, in particular crankshafts (1), by mechanical material removal with a bed (14), - two mutually directed, rotatably drivable Spindles (15, 16) for receiving and driving the ends of the workpiece, in particular a crankshaft (1), about the longitudinal direction (10), the Z axis, at least one tool support (12, 13) which is at least in X- Direction can be moved in a defined manner, characterized in that one spindle (15) can be driven at high speed and the other spindle (16) can be driven at low speed and is able to move to defined rotational positions (C1 axis) and at least one of the spindles (15, 16) has a rotational position straightening device for the workpiece.

14. Machine according to claim 13, characterized in that the tool support (12, 13) has, in addition to the movability in the X direction, either via a movability in the Y direction or via a pivoting possibility about the Z direction (C2 axis) ,

15. Machine according to one of the preceding device claims, characterized in that the rotary drive of the slower spindle (16) is a self-locking rotary drive, and in particular has a worm / worm wheel pairing.

16. Machine according to one of the preceding device claims, characterized in that the machine (2) has tool supports (12, 13), one of which is a tool for workpiece-based machining processes, in particular a turning tool, a broaching tool, a turning broaching tool, one turning-broaching tool or a finishing tool carries, and the other at least one tool for a tool-based machining process, in particular an orthogonal milling cutter or an externally toothed milling cutter.

17. Machine according to one of the preceding device claims, characterized in that the drives of the spindles (15, 16) can be uncoupled.

18. Machine according to one of the preceding device claims, characterized in that the spindles (15, 16) are driven by the same motor (17).

19. Machine according to one of the preceding device claims, characterized in that the tools are arranged on at least one disk-shaped tool base body (18, 19) on the outer circumference, and in particular the tools for tool-based methods over the entire circumference of the base body (18, 19) are distributed.

20. Machine according to one of the preceding device claims, characterized in that the machine is equipped with tools of different materials, in particular materials, for high cutting speeds, in particular above 180 m / s on the one hand and low cutting speeds, in particular a maximum of 180 m / s on the other is, in particular with hard metal or ceramic cutting materials on the one hand and high-speed steel (HSS), i.e. steel tools, on the other.

21. Machine according to one of the preceding device claims, characterized in that the machine has only a single tool support (12) on which tools for high cutting speeds and tools for low cutting speeds are arranged, but all of which are tools for workpiece-based machining processes are.

22. Machine according to one of the preceding device claims, characterized in that at least one of the spindles, in particular both spindles (15, 16) on the one hand with a chuck exciting on the outer circumference, in particular a jaw chuck (20) or (21) and on the other hand with a centering tip (22) or (23), in particular a centering tip movable relative to the chuck in the Z direction.

23. Machine according to one of the preceding device claims, characterized in that the centering tip (22, 23) is freely rotatably mounted.

24. Machine according to one of the preceding device claims, characterized in that the centering tip (22, 3) can be axially fixed in a defined Z position with respect to the jaw chuck.

25. Machine according to one of the preceding device claims, characterized in that at least one, in particular both spindles (15, 16) via a longitudinal stop (24) or (25) either for the Z position of the centering tip (22, 23) relative to the Jaw chuck (20, 21) or opposite the spindle (15, 16) or has a longitudinal stop for the workpiece with respect to the jaw chuck (20, 21).

26. Machine according to one of the preceding device claims, characterized in that the axial forces with which the centering tips (22, 23) can be acted upon are adjustable, in particular with regard to the fact whether the respective axial force is greater or less than the axial force of the act on the others Centering point, e.g. B. (23).