DE102016101196B4 - Method and cylindrical grinding machine for grinding gear shafts, camshafts or crankshafts and machine control program for a control device for carrying out the method - Google Patents

Abstract

Method for grinding gear shafts, camshafts or crankshafts, comprising the following steps: - receiving a wave-shaped workpiece (30) on a workpiece spindle (22), - providing a group of setting blocks (34, 36, 38, 40) along a axial longitudinal extent of the workpiece (30) are spaced from each other, wherein the pegs (34, 36, 38, 40) can assume an attack state and a non-attack state, the pegs (34, 36, 38, 40) supporting in the attack state - providing at least one grinding spindle (54, 56, 58, 60, 154, 156, 158, 160) with at least one grinding tool (62, 64, 66, 68, 162, 164, 166, 168) machining the workpiece (30), comprising: generating a feed movement to bring the grinding tool (62, 64, 66, 68; 162, 164, 166, 168) into engagement with the workpiece (30), Generation of a relative rotation between the Sc grinding tool (62, 64, 66, 68; 162, 164, 166, 168) and the workpiece (30), and - driving the group of pegs (34, 36, 38, 40) to selectively the pegs (34, 36, 38, 40) in the attack state or the Non-attack state, with a change between the attack state and the non-attack state during processing.

Description

The present disclosure relates to a method for grinding gear shafts, camshafts or crankshafts. The disclosure further relates to a cylindrical grinding machine for grinding gear shafts, camshafts or crankshafts. Finally, the disclosure further relates to a machine control program for a control device for carrying out the method.

From the DE 20 2010 004 788 U1 a milling machining center for complete machining of workpieces is known, with a tool spindle and a machine control, wherein an adapter device for deep hole drill is provided which can be releasably attached to the tool spindle, the adapter device comprises a base body and at least one base body associated with the bezel for supporting the deep hole drill, and a drive for moving the steady rest along a feed axis of the tool spindle comprises.

From the DE 1 271 501 A a multi-spindle automatic lathe for individual workpieces is known, which are stretched between tips and supported by a spindle drum, arranged on a support lunettes with rollers, the lunettes are radially adjustable towards the workpiece, including radially movable carriage are provided on Cams are movable.

From the EP 0 788 419 B1 a device for deep rolling of Kehlungen in journal and main bearings of a crankshaft is known.

From the US 5,103,596 A For example, a control device for a cylindrical work grinding machine is known, comprising a deflection suppressing device including abutment members including the cylindrical workpiece on both sides thereof and a contact force of the abutment members with a control unit connected to the deflection suppressing device adjust.

From the DE 38 14 038 A1 An external cylindrical grinding machine for crankshafts is known, which has an adjustable steady rest for supporting the workpiece to be machined

From the EP 0 724 500 B1 a grinding machine with a work table and a grinding wheel is known, against which the work table is displaceable, wherein the work table carries a headstock with respect to this adjustable tailstock and an adjustable workpiece support, and wherein at least the headstock or the tailstock and additionally the workpiece support opposite the work table are adjustable.

From the DE 10 2011 102 113 A1 is a grinding machine for the grinding of outer surfaces of a workpiece, in particular for external cylindrical grinding and / or external cylindrical grinding, known, with a workpiece holder, which is adapted to rotatably support a workpiece and / or controlled to drive rotationally, with at least a first and a second set of grinding spindles, wherein the at least first and second sets of grinding spindles are displaceable between a primary engaged position and a secondary engaged position, the first set of grinding spindles comprising at least a first primary grinding spindle and a first secondary grinding spindle, the second grinding spindle set having at least a second primary grinding spindle and a second secondary grinding spindle; wherein at least the primary or secondary grinding spindle of the first and / or second grinding spindle set comprises a grinding wheel package comprising a plurality of substantially rotationally symmetrical grinding wheels has perflächen which are stepped to each other and / or delimited from each other.

The from the DE 10 2011 102 113 A1 known grinding machine is particularly suitable for machining elongate wave-shaped workpieces. These include, for example, camshafts, transmission shafts, crankshafts, drive shafts or the like. According to at least some embodiments of DE 10 2011 102 113 A1 is the workpiece to be machined on a workpiece holder receivable, which can also be referred to as a workpiece spindle. Furthermore, the grinding machine has a first spindle unit and a second spindle unit, which may, for example, each comprise a primary spindle and a secondary spindle. This has the advantage that without a re-tightening or retooling of the grinding machine different machining operations can be performed that require different processing tools (grinding wheel). This may include, for example, rough machining and finishing.

Another advantage of the DE 10 2011 102 113 A1 known grinding machine is that the two spindle units, which can also be referred to as spindle sets, face each other, wherein currently used for machining grinding tools face each other and preferably have only a very small distance to each other. This allows, for example, the machining of shaft components with a pronounced longitudinal extension (large length-diameter ratio) without the need for a feed movement (in the longitudinal direction of the workpiece). Such machining can also be referred to as plunge grinding. In other words, the grinding tools may be designed to match the desired contour of the Sufficiently reflect the workpiece. Accordingly, a grinding tool may be referred to as a grinding wheel package. Such a grinding wheel package consists of a plurality of segments or sections, which may have a different shape from each other.

It is understood that grinding machines, in particular cylindrical grinding machines, can also be designed otherwise. So it is not absolutely necessary to provide two grinding spindle sets. It is also conceivable to provide only one set of grinding spindles, on which a correspondingly designed grinding tool is received.

The present disclosure is particularly concerned with the grinding of transmission shafts, camshafts or crankshafts typically used in the automotive field. The wave-shaped workpieces do not necessarily have to be completely rotationally symmetrical. Rather, the workpieces may have eccentrically shaped sections, such as in the form of cams, cheeks or pins. In general, the workpieces have a large length to diameter ratio, which may be about 3: 1, 5: 1 or even 7: 1 or more. Reference diameter for this purpose may, for example, be a maximum diameter of the workpiece.

In particular, in mass production or mass production of components for drive technology, such as motors, drive trains, valve trains, gearbox or the like, the shortest possible cycle times must be achieved. However, this must not be at the expense of accuracy or the required quality. Required accuracies and tolerances to be achieved are, for example, in the case of gear shafts in the range of a few microns (microns). Cycle times of machining as part of mass production or mass production for a gear shaft are well below 60 s (seconds).

A good compromise between the shortest possible cycle time and optimal accuracy can be achieved, for example, by a multi-stage machining method, which includes, for example, pre-grinding and finish-grinding the workpiece, wherein different grinding tools are used in each case.

It has been shown that, on the one hand, satisfactory results with regard to the cycle time and the machining accuracy can be achieved with known grinding machines, but further optimization is desired. This applies in particular to the machining of corrugated workpieces with pronounced longitudinal extension.

Against this background, the disclosure has the object of specifying a method for grinding of gear shafts, camshafts or crankshafts, which allows a further optimization of the machining process and, in particular given operating parameters, such as a given machining time, allows a further increase in accuracy. Preferably, the repeatability is improved, so that overall the process quality can increase. Furthermore, in the context of the present disclosure, a cylindrical grinding machine for grinding gear shafts, camshafts or crankshafts is to be specified, which is designed to carry out the machining method. Preferably, the method can be used with little effort even in existing machine tools. Preferably, existing machine tools can be easily retrofitted or provided with control technology in order to allow execution of the method. Another aspect of the present invention is to provide a machine control program that enables a machine tool to carry out the method.

• – Aufnahme eines wellenartig gestalteten Werkstücks an einer Werkstückspindel,
• – Bereitstellung einer Gruppe von Setzstöcken, die entlang einer axialen Längserstreckung des Werkstücks voneinander beabstandet sind, wobei die Setzstöcke einen Angriffszustand und einen Nicht-Angriffs-Zustand einnehmen können, wobei die Setzstöcke im Angriffszustand stützend an das Werkstück angreifen,
• – Bereitstellung zumindest einer Schleifspindel mit zumindest einem Schleifwerkzeug, und
• – Bearbeitung des Werkstücks, umfassend: – Erzeugung einer Zustellbewegung, um das Schleifwerkzeug in einen Eingriff mit dem Werkstück zu bringen, – Erzeugung einer Relativrotation zwischen dem Schleifwerkzeug und dem Werkstück, und – Ansteuerung der Gruppe von Setzstöcken, um die Setzstöcke selektiv in den Angriffszustand oder den Nicht-Angriffs-Zustand zu versetzen, wobei während der Bearbeitung ein Wechsel zwischen dem Angriffszustand und dem Nicht-Angriffs-Zustand erfolgt.

With regard to the method, the object of the invention is achieved by a method for grinding gear shafts, camshafts or crankshafts, comprising the following steps:

• Receiving a wave-shaped workpiece on a workpiece spindle,
• Providing a set of pegs spaced apart along an axial longitudinal extent of the workpiece, the pegs being capable of engaging an attack condition and a non-engagement condition, the pegs engaging the engagement member in a supporting condition,
• - Providing at least one grinding spindle with at least one grinding tool, and
• Machining the workpiece, comprising: producing a feed movement to bring the grinding tool into engagement with the workpiece, generating a relative rotation between the grinding tool and the workpiece, and controlling the group of setting sticks to selectively set the setting sticks in the attack state or to offset the non-assault state, during which a change occurs between the attack state and the non-attack state.

The object of the invention is completely solved in this way.

Namely, according to the invention, the method allows a selective attack or non-attack of the setting sticks against the workpiece. A switch between the attack state and the non-attack state occurs during machining of the workpiece, preferably multiple times. It has been found that in this way the machining accuracy and also the repeatability of the machining can be increased. In contrast to machining where the pegs permanently engage the workpiece, selective activation and deactivation of the pegs can contribute to increased manufacturing quality. This can be the case even if the other process parameters are not or only insignificantly changed.

In other words, it has been shown that an at least temporary relieving of at least one setting stick of the group of setting sticks can increase the achievable manufacturing accuracy.

Plinths as such are well known in the art. Buttocks are also called lunettes. In the context of this disclosure, buttocks generally mean support elements which are fixed directly or indirectly on the machine tool or grinding machine. Butt blocks are commonly used to support long or overlong workpieces during machining. On the one hand, this can apply to workpieces that are only clamped on one side. However, pegs are also used for workpieces that are accommodated on both sides, such as a workpiece spindle and a tailstock. Plinths counteract static deformations and dynamic deformations.

Advantages and effects according to the disclosure can in particular emerge in the case of corrugated workpieces with pronounced longitudinal extension. This includes, for example, transmission shafts, drive shafts, camshafts or crankshafts. The workpieces preferably have a length-diameter ratio of at least 3: 1, preferably at least 5: 1, more preferably at least 7: 1.

The pegs are designed in particular as active pegs and can attack in their attack state on the workpiece. This may include, for example, a defined contact force or holding force. In the non-attack state, the pegs can be lifted off the workpiece on the one hand. However, it is also conceivable that the contact force or driving force of the pegs in the non-attack state, compared to the attack state, is significantly reduced.

The method is suitable according to at least some embodiments, in particular for machining by means of plunge grinding or Schrägeinstechschleifen, wherein the grinding tool without axial feed (in the longitudinal direction) relative to the workpiece acts on this. Furthermore, the grinding tool is preferably designed as a segmented tool and comprises a plurality of sections which are associated with peripheral portions of the workpiece. This includes embodiments in which a grinding tool or two grinding tools are engaged, which have a longitudinal extension corresponding to at least 30%, preferably at least 50%, more preferably at least 70% of the longitudinal extension of the workpiece.

During the machining process, at least one setter is alternately in the active state and in the inactive state, for example in accordance with a rectangular function or a sine function. Accordingly, the states may be associated with discrete values or ranges of continuous values.

According to an example embodiment of the method, the group of setting sticks has at least two individually controllable setting sticks, wherein at least temporarily a first setting stick is in the attack state during processing, while a second setting stick is in the non-attacking state, and wherein during the Processing at least temporarily the first set of stick in the non-attack state, while the second set of peg is in the attack state.

In other words, two or more pegs are provided, which can be operated alternately or at least offset in time to each other. According to a further embodiment, the at least two setting sticks are operated alternately during the machining of the workpiece in the attack state and in the non-attack state. Thus, while the first setter is in the attack state, the second setter is at least temporarily in the non-attack state, and vice versa. This measure can contribute to further increase the manufacturing quality.

According to a further embodiment of the method, the at least two setting sticks are at least temporarily in the same state when the first set stick is transferred from the attack state to the non-attack state and the second set stick from the non-attack state into the attack state. In other words, there may be a temporal overlap of the states of the pegs. This can relate in particular to the attack state. However, according to alternative embodiments, this may also relate to the non-attack state.

According to this measure, it can be ensured that at least one set of sticks is always in the attack state. This can be about prevent excessive deflection of the workpiece.

According to a further embodiment of the method, at least two sets of pegs of the set of pegs are operated simultaneously in the attack state and in the non-attack state and are switched back and forth between the attack state and the non-attack state. This may, for example, relate to a subset of the group of pegs. So it is conceivable that a total of four pegs are provided, of which two are operated simultaneously in the attack state and in the non-attack state. In each case two of the four pegs can therefore be controlled synchronously. According to an alternative embodiment, however, it is also conceivable that all of the pegs are operated simultaneously in the attack state and in the non-attack state.

The optimal control of the group of pegs can be determined empirically or heuristically, depending on the application. It is conceivable, for example, to first define the duration and sequence of states for a setting stick or a group of setting sticks for a new application (a new type of workpiece) on the basis of empirical values. On the basis of such a basic state, optimizations can be carried out, in particular with regard to the production accuracy to be achieved or the reproducibility. Similarly, the timing or order of activation and deactivation of the individual setting sticks can be determined, cf. For illustrative purposes, for example, the firing order of the cylinders of an internal combustion engine.

It has been found that with a manageable effort based on a variation of the sequence of activation / deactivation or the duration of the respective states, a clear optimization of the production result can be achieved.

However, it is also conceivable to vary the control of the group of setting sticks on the basis of stochastic or quasi-stochastic methods in order in turn to select an optimum on the basis of a plurality of tests.

According to a further embodiment of the method, the setting sticks are further operable in a transient state, wherein the transient state describes an impending change between the attack state and the non-attack state. In this way, the transient state can be used to announce a change of state between the attack state and the non-attack state, and vice versa. In this way, the machine tool can be informed about the pending state change with a certain lead time. This can be used to at least temporarily adjust operating parameters to facilitate the transition between the attack state and the non-attack state.

According to a further embodiment of the method, the setting sticks act in the non-attack state with a reduced holding force on the workpiece. Alternatively, these pegs are lifted in the non-attack state of the workpiece. Conversely, the pegs act in the attack state in a defined manner on the workpiece. This can in particular include a defined holding force or contact force.

According to a further embodiment of the method, a feed force with which the grinding wheel acts on the workpiece is reduced when one of the setting sticks is switched over between the attack state and the non-attack state. This can further increase the achievable accuracy. It is understood that the delivery force does not necessarily have to be reduced each time one of the pegs is changed between the attack state and the non-attack state. However, it has been found that it can be advantageous if the corresponding load of the workpiece, which is connected to the feed force, is reduced when at least one of the setting sticks is switched.

According to one development of this embodiment, the delivery force is reduced, while the setter is in a transition state, which initiates a change between the attack state and the non-attack state (and vice versa). In this way altogether a smooth transition between the attack state and the non-attack state can be made possible. The short-term reduction of the delivery force can relieve the workpiece and lead to a further increased quality.

It goes without saying that the delivery force does not necessarily have to be reduced to zero. Rather, embodiments are conceivable in which the delivery force, starting from a previous level (about 100%) is reduced to a reduced level (about 50%, 20% or 10%). The feed force is usually oriented perpendicular to the longitudinal axis of the workpiece. When Schrägeinstechschleifen deviations may result. The feed force can cause a deflection of the workpiece. In addition to the delivery force and the weight of the workpiece can cause a deflection. Furthermore, dynamic deformations during processing are conceivable. Usually, the pegs are designed to minimize unwanted workpiece deformations (such as deflection) caused by the workpiece itself (dead weight as well as dynamic effects during machining) or just by the tool (chip force of the grinding wheel or delivery force of the grinding wheel) are generated.

According to a further embodiment of the method, at least some sets of the set of pegs are switched back and forth several times between the attack state and the non-attack state during processing, wherein preferably at least two pegs of the group of pegs alternate between the attack state and the non-attack state. Attack state to be switched back and forth.

A signal curve of the activity of a set stick resulting from the change between the attack state and the non-attack state can in principle comprise a binary course, ie assume exactly two discrete values, which are connected by steep edges. However, it is also conceivable that the change between the attack state and the non-attack state causes a waveform that is designed approximately sinusoidal. This is especially true when the setter is operable in addition to the attack state and the non-attack state in the transition state. The states themselves do not necessarily have to be assigned a discrete, constant value. Rather, a state, such as a sinusoidal signal, a certain range of values of the signal include (about attack state: 90% to 70%, transition state: 70% to 30%, non-attack state: 30% to 0%). It is understood that other designs and intermediates are conceivable.

Overall, a state period may result that includes the attack state and the non-attack state and, if present, the transition state. The duration of such a period may be, for example, values of 0.5 s (seconds) up to 2 s, 5 s or even more.

In principle, the duration of the non-attack state can correspond to the duration of the attack state. However, embodiments are conceivable in which the duration of the attack state is greater than the duration of the non-attack state.

• – ein Maschinenbett,
• – eine Werkstückaufnahme mit einer Werkstückspindel,
• – zumindest eine Schleifspindel mit einem Schleifwerkzeug,
• – eine Gruppe von Setzstöcken, die voneinander beabstandet angeordnet sind, wobei die Setzstöcke in einem Angriffszustand und einem Nicht-Angriffs-Zustand betreibbar sind, und wobei die Setzstöcke dazu ausgebildet sind, im Angriffszustand stützend an ein Werkstück anzugreifen, das an der Werkstückaufnahme aufgenommen ist, und
• – eine Steuereinrichtung, die dazu ausgebildet ist, die Setzstöcke während der Bearbeitung des Werkstücks selektiv in den Angriffszustand und den Nicht-Angriffs-Zustand zu versetzen, wobei ein definierter Wechsel zwischen dem Angriffszustand und dem Nicht-Angriffs-Zustand erfolgt, wobei zumindest einige der Setzstöcke der Gruppe von Setzstöcken als aktive Setzstöcke gestaltet sind und mit zumindest einem Setzstockantrieb versehen oder koppelbar sind, um einen jeweiligen Setzstock wahlweise in den Angriffszustand oder den Nicht-Angriffs-Zustand zu versetzen.

The grinding machine achieves the object of the invention by a cylindrical grinding machine for grinding gear shafts, camshafts or crankshafts, which has the following:

• - a machine bed,
• A workpiece holder with a workpiece spindle,
• At least one grinding spindle with a grinding tool,
• A set of pegs spaced apart from each other, the pegs being operable in an attack state and a non-engagement state, and wherein the pegs are configured to resiliently engage a workpiece received on the workpiece receiver in the engaged state , and
• - A control device which is adapted to put the setting sticks selectively during the machining of the workpiece in the attack state and the non-attack state, wherein a defined change between the attack state and the non-attack state takes place, wherein at least some of Butt blocks of the group of prop sticks are designed as active pegs and are provided with at least one butt drive or can be coupled in order to set a respective peg in either the attack state or the non-attack state.

Also in this way the object of the invention is completely solved.

Preferably, the grinding machine is designed for plunge grinding or Schrägeinstechschleifen. This may include embodiments in which the machining of the workpiece does not include a feed movement along the longitudinal axis of the workpiece.

The grinding machine is preferably suitable for carrying out the machining method according to at least one of the aspects described here. The group of pegs may comprise about 2, 3, 4 or even more pegs, which are spaced apart along the longitudinal extent of the workpiece, directly or indirectly received on the machine bed.

According to one embodiment of the grinding machine, the control device is further configured to control a feed drive of the grinding spindle in order to reduce a feed force of the grinding wheel onto the workpiece during a transition of a setting stick between the attack state and the non-attack state.

According to a further embodiment of the grinding machine, the setting sticks and the grinding spindle are arranged on opposite sides of the received workpiece, wherein the setting sticks, in particular in the attack state, provide a force component opposing the feed force, which acts on the workpiece. In this way, a bending of the workpiece due to the delivery forces can be effectively counteracted.

At least some buttocks of the group of props are designed as active pedestals and are provided with at least one butt drive or can be coupled to selectively place a respective pedestal in the attack state or the non-attack state.

By way of example, active setting sticks can comprise gripping arms and the like, which can be displaced at least in sections in order to bring about the change of state. The Setzstockantrieb can be designed as a hydraulic drive or pneumatic drive. It is also conceivable to design the Setzstockantrieb as electrical, magnetic or electromechanical drive.

According to a further embodiment of the grinding machine, the control device is further adapted to put the setting sticks in a transitional state, which is traversed at a change between the attack state and the non-attack state, wherein during the transition state, the grinding spindle is controlled defined, in particular to control the feed force of the grinding wheel on the workpiece.

For purposes of illustration, reference is made to a traffic light comprising a red, a green and a yellow signal. The attack state corresponds to the green signal by way of example. The non-assault state corresponds to the red signal accordingly. The transition state corresponds to the yellow signal, which announces the change between the green signal and the red signal (and vice versa). In other words, a structural change does not necessarily have to result during the transitional state at the setting stick itself or at its butt drive. Rather, the transition state announces the imminent change between the attack state and the non-attack state.

According to a further embodiment of the grinding machine, the at least one grinding spindle carries at least one grinding wheel designed as a grinding wheel package, wherein the grinding wheel package has a core which is designed in several parts and has different axial sections which are joined together, and wherein the grinding wheel package has a plurality of grinding segments, the corresponding sections of the workpiece to be machined are assigned. The core can be designed at least in sections as a composite body, in particular as a fiber composite body.

Such designed grinding wheel packages allow grinding wheels with a large axial extent, which can thus process large axial sections of a workpiece simultaneously. It has been found that, in particular, when the workpiece is machined simultaneously in a piercing process at several sections, the selective actuation of the setting sticks for the transition between the attack state and the non-attack state leads to a significant improvement in accuracy.

It is conceivable that the grinding wheel designed as a grinding wheel package has a longitudinal extent which corresponds substantially to the longitudinal extent of the workpiece. Accordingly, the workpiece can basically be worked on all or almost all of its circumference.

According to a further embodiment of the grinding machine a plurality of spindle units are provided, in particular two spindle units, wherein at least one of the spindle units has a grinding spindle with a cantilevered grinding wheel, and wherein the spindle units are preferably accommodated facing each other on the machine bed. The spindle units can generally also be described as spindle sets. The spindle units may each comprise one or more grinding spindles. The flying support of the grinding wheel makes it possible to arrange two spindle units, which are arranged facing one another on the machine bed, in such a way that the grinding wheels are very close. Accordingly, the workpiece can be processed simultaneously with both grinding wheels, whereby a considerable portion of the longitudinal extent of the workpiece can be machined.

According to a further embodiment of the grinding machine, at least one spindle unit is provided, which comprises two grinding spindles, wherein the two grinding spindles have a common travel drive, and wherein the two grinding spindles of the spindle unit are mutually movable into an active position or a passive position with respect to the workpiece, in particular by a pivot drive, which is assigned to the spindle unit.

Accordingly, roughing and fine machining can be performed with only one spindle unit comprising two grinding spindles. In general, the combination of several processing steps is conceivable that require different grinding tools.

By way of example, the grinding machine is designed such that two spindle units are provided, each comprising two grinding spindles, wherein the grinding spindles of the spindle units have cantilevered grinding wheels. Each of the spindle units may include a pivot drive to selectively engage one of the two grinding wheels in engagement with the workpiece. The named Configuration allows a complete machining or almost complete machining of the workpiece in just one clamping. Preferably, this can be done by means of plunge grinding or Schrägeinstechschleifen without a feed movement along the longitudinal axis of the workpiece is required.

The object underlying the disclosure is further solved by a machine control program having program code adapted to cause a control device of a cylindrical grinding machine for grinding gear shafts, camshafts or crankshafts to carry out the steps of the method according to one of the aspects mentioned here, if Machine control program is executed on the control device.

It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

Further features and advantages of the invention will become apparent from the following description of several preferred embodiments with reference to the drawings. Show it:

1 a simplified perspective view of an embodiment of a grinding machine with a Setzstockanordnung;

2 a simplified perspective view of an alternative embodiment of a grinding machine with a Setzstockanordnung;

3 a schematic, highly simplified plan view of an assembly comprising a workpiece, a group of pegs and two grinding tools, which are controllable via a control device;

4 a partial perspective view of a grinding machine for illustrating an exemplary embodiment of a setting stick;

5 a state diagram illustrating a state profile of a group of pegs;

6 a state diagram illustrating a state profile of a group of pegs, the course of the representation according to 6 according to the course 5 different;

7 a state diagram for illustrating the state profile of a group of pegs, with a state progression of a feed drive is also illustrated for explanation;

8th a further state diagram for temporal comparison of different states that can take a first set and a second set floor;

9 a schematic block diagram illustrating an embodiment of a method for grinding workpieces; and

10 a schematic block diagram illustrating partial steps of an embodiment of a method for grinding workpieces.

1 shows a schematic perspective view of a machine tool 10 , which is designed as a grinding machine.

The grinding machine 10 has a machine bed 12 on, which can also be referred to as a frame. At the machine bed 12 are guides 16 . 18 educated. Along the guides 16 . 18 can be components of the grinder 10 be determined and optionally.

In at least some of the figures shown here, a coordinate system is shown by way of illustration. Generally, a longitudinal direction is designated by X. A transverse direction is designated Z. A vertical direction is designated Y. In this way three translational axes X, Y and Z are defined. A respective rotation about the axes X, Y, Z defines a corresponding axis of rotation. It is understood that for purposes of description, alternative coordinate systems, such as machine coordinate systems and / or workpiece coordinate systems, are conceivable. The required intellectual transformation is readily possible for the person skilled in the art.

It is understood that terms used in the context of this disclosure, such as first element, second element, primary element, secondary element, are primarily used for purposes of distinction and, in particular, do not relate to qualitative weighting.

The grinding machine 10 also has a workpiece holder 20 on, the example of the leadership 16 is included. The workpiece holder 20 includes a workpiece spindle 22 , The workpiece spindle 22 may include a drive to selectively drive a picked tool. By way of example, the workpiece holder comprises 20 a first workpiece holder 24 and a second workpiece holder 26 , between the one workpiece 30 is included. The first workpiece holder 24 can be a clamping device for the workpiece 30 include. The second workpiece holder 26 is exemplified as a tailstock. The workpiece spindle 22 may also have a C-axis drive 28 include a defined twisting of the workpiece 30 allowed around its longitudinal axis. The longitudinal axis of the workpiece 30 is parallel to the X-axis. The C-axis drive 28 allows a defined rotational alignment of the workpiece 30 , This allows about the machining of eccentric contours of the workpiece 30 , In this way, about cams or the like can be ground.

At the workpiece 30 it is about a camshaft, a transmission shaft, a drive shaft or a crankshaft. The workpiece 30 has a pronounced longitudinal extent. In this respect, the workpiece can 30 also be referred to as an elongated workpiece. The workpiece 30 is waved. In the embodiment according to 1 is the workpiece 30 on both sides of the workpiece holder 20 taken, namely between the first workpiece holder 24 and the second workpiece holder 26 , It is basically conceivable, the workpiece 30 take only one side, so about the second workpiece holder 26 to renounce, which is designed as a tailstock.

workpieces 30 , which are designed as a transmission shaft, crankshaft, camshaft or drive shaft, often have a pronounced longitudinal extent. This includes a high length-to-diameter ratio, such as a ratio between length and diameter of the workpiece 30 of at least 3: 1, at least 5: 1, or at least 7: 1. Such long workpieces 30 are often on both sides of the workpiece holder 20 added. Furthermore, a support of the workpiece 30 along a longitudinal extent by a Setzstockanordnung 32 which is about a first set of pegs 34 and a second setter 36 includes.

The pegs 34 . 36 are designed to support the workpiece 30 Attack to a deformation or bending of the workpiece 30 counteract. Preferably, the pegs 34 . 36 designed as active pegs. This includes embodiments in which the pegs 34 . 36 provided with drives or can be coupled to the pegs 34 . 36 to selectively provide an attack state or a non-attack state.

Thus, at least according to some embodiments, there is no permanent support by the setting sticks 34 . 36 , Rather, the pegs 34 . 36 Temporarily activated and temporarily deactivated to increase the accuracy of the grinding process. This can be a simultaneous actuation of the pegs 34 . 36 include. Furthermore, this can be a mutual actuation of the pegs 34 . 36 include. The pegs 34 . 36 can be activated in phase or out of phase. An in-phase activation is then, if several pegs 34 . 36 simultaneously in the attack state or in the non-attack state. A phase-shifted or out-of-phase activation occurs when at least temporarily one butt in the attack state and another buttstock is simultaneously in the non-attack state.

Embodiments of the present disclosure are concerned with the control of jig assemblies 32 holding several pegs 34 . 36 include. This will be explained in more detail below.

The actual (material-removing) machining of the grinding machine 10 done by spindle units 50 . 52 , which can also be referred to as spindle sets. The grinding machine 10 has at least one spindle unit 50 . 52 on. According to the basis of the 1 illustrated embodiment includes the grinding machine 10 a first spindle unit 50 and a second spindle unit 52 , The spindle units 50 . 52 each comprise at least one headstock.

The first spindle unit 50 includes a primary grinding spindle 54 and a secondary grinding spindle 56 , The second spindle unit 52 includes a primary grinding spindle 58 and a secondary grinding spindle 60 , On the grinding spindle 54 is a grinding tool 62 added. On the grinding spindle 56 is a grinding tool 64 added. On the grinding spindle 58 is a grinding tool 66 added. On the grinding spindle 60 is a grinding tool 68 added.

The grinding tools 62 . 64 . 66 . 68 are preferably designed as grinding wheels. At least some of the grinding tools 62 . 64 . 66 . 68 are exemplified as grinding wheel packages and include a plurality of segments, which may have approximately different diameters. The grinding tools 62 . 64 . 66 . 68 are usually, at least on their working surfaces, designed rotationally symmetric.

The spindle units 50 . 52 are designed such that each used for machining grinding tools 62 . 64 . 66 . 68 the spindle units 50 . 52 facing each other. This includes an exemplary embodiment in which the grinding tools 62 . 64 . 66 . 68 each flying on the associated grinding spindle 54 . 56 . 58 . 60 are included.

The spindle unit 50 is at a table 72 added. The spindle unit 52 is at a table 74 added. The table 72 can be referred to as the first table. The table 74 can also be called a second table. The first table 72 has a leadership base 76 and a sled 78 on. The second table 74 has a leadership base 80 and a sled 82 on. The table 72 . 74 are an example of the leadership 18 movably received on the machine bed. In this way, a movement in the X direction parallel to the longitudinal extent of the workpiece 30 be effected. The leadership base 76 . 80 and the sled 78 . 82 the table 72 . 74 can be moved relative to each other. This allows movement along the Z axis. This movement is also referred to as a feed movement or puncture movement. The table 72 . 74 can also be referred to as cross tables or cross slides.

The first spindle unit 50 further comprises a pivot drive 86 that has a pivot axis 90 Are defined. The spindle unit 52 includes a rotary actuator 88 that has a pivot axis 92 includes. The rotary actuator 86 can also be referred to as the first quarter turn actuator. The rotary actuator 88 can also be referred to as a second pivot drive. In 1 are the swivel axes 90 . 92 the quarter-turn actuators 86 . 88 parallel to the longitudinal axis of the workpiece 30 or oriented to the X-axis.

The table 72 . 74 and the part-turn actuators associated therewith 86 . 88 can be used to selectively the primary grinding spindle 54 . 58 or the secondary grinding spindle 56 . 60 in engagement with the workpiece 30 bring to. By way of example, the primary grinding spindles 54 . 58 with the associated grinding tools 62 . 66 be used for a first processing stage. Accordingly, the secondary spindles 56 . 60 with the associated grinding tools 64 . 68 be used for a second processing level. The various processing stages can be about the processing of different sections of the workpiece 30 include. However, the various processing stages may include rough machining and finishing.

Furthermore, in 1 one with 96 designated control device indicated, which serves to functions and machining processes of the grinding machine 10 to control. This includes, in particular, a control of travel drives, spindle drives and a control of the setting bar arrangement 32 ,

2 illustrates in a simplified perspective view a modified embodiment of a grinding machine 110 , The grinding machine 110 is the basis of the 1 illustrated grinding machine 10 designed at least similar, so that in the following priority is given to modified components and features. It is understood that assemblies, modules and functions of grinders 10 . 110 according to the 1 and 2 combinable with each other and / or from one of the two grinding machines 10 . 110 to the other are transferable.

The grinding machine 110 is similar to the grinder 10 according to 1 with a buttstock arrangement 32 Mistake. The buttstock arrangement 32 the grinding machine 110 exemplarily comprises four pegs 34 . 36 . 38 . 40 , Such a design is basically also in the grinding machine 10 according to 1 imaginable. The pegs 34 . 36 . 38 . 40 are an example of the leadership 16 added. The pegs 34 . 36 . 38 . 40 are along the longitudinal extent of the workpiece 30 axially spaced apart and directly or indirectly with the machine bed 12 coupled.

The grinding machine 110 is further provided with a first spindle unit 150 provided with a first set of grinding spindles. Next to it is a second spindle unit 152 provided comprising a second set of grinding spindles. The first spindle unit 150 is a primary grinding spindle 154 and a secondary grinding spindle 156 assigned. The second spindle unit 152 is a primary grinding spindle 158 and a secondary grinding spindle 160 assigned.

The primary grinding spindle 154 the first spindle unit 150 carries a grinding tool 162 , The secondary grinding spindle 156 the first spindle unit 150 carries a grinding tool 164 , The primary grinding spindle 158 the second spindle unit 152 carries a grinding tool 166 , The secondary grinding spindle 160 the second spindle unit 152 carries a grinding tool 168 , The grinding tools 162 . 164 . 166 . 168 the spindle units 150 . 152 are stored on the fly. This allows the grinding tools currently used for the machining 162 . 164 . 166 . 168 very close to each other, to the workpiece 30 to be able to process as large as possible.

The grinding spindles 154 . 156 . 158 . 160 each spindle unit 150 . 152 are arranged facing away from each other. The of the respective spindle unit 150 . 152 associated grinding spindles 154 . 156 . 158 . 160 can be concentric with each other. However, it is also a parallel offset between the grinding spindles 154 . 156 . 158 . 160 at the respective spindle unit 150 . 152 imaginable.

The spindle unit 150 is at a table 172 included, which is a leadership base 176 and a sled 178 includes. The spindle unit 152 is at a table 174 included, which is a leadership base 180 and a sled 182 includes. The table 172 . 174 , allow movement of the spindle units 150 . 152 with the grinding spindles picked up 154 . 156 . 158 . 160 in a plane spanned by the X and Z axes.

The first spindle unit 150 further comprises a pivot drive 186 that has a pivot axis 190 Are defined. The second spindle unit 152 further comprises a pivot drive 188 that has a pivot axis 192 Are defined. The pivot axes 190 . 192 are oriented parallel to the Y-axis. The pivot axes 190 . 192 can also be referred to as so-called B-axes. The quarter-turn actuators 186 . 188 on the one hand permit selective activation or deactivation of the primary grinding spindles 154 . 156 or the secondary grinding spindles 156 . 160 , In addition, the quarter turn actuators can 186 . 188 also be used to the grinding tools 162 . 164 . 166 . 168 diagonally opposite the workpiece 30 to hire. In other words, in such a position, the longitudinal axes of the workpiece 30 and the grinding tool 162 . 164 . 166 . 168 have a defined offset angle to each other. In this way can be approximately conical sections of the workpiece 30 to be edited.

In 2 is the first spindle unit 150 shown in an intermediate state, such as when changing between the primary grinding spindle 154 and the secondary grinding spindle 156 is present.

With regard to the basic structural design of the machine tool 10 according to 1 as well as the machine tool 110 according to 2 is again explicitly on the DE 10 2011 102 113 A1 directed.

3 shows a schematic highly simplified representation of a plan view of a workpiece 30 between a first workpiece holder 24 and a second workpiece holder 26 is added to by grinding tools 62 . 66 to be processed. Furthermore, in 3 a buttstock arrangement 32 indicated, the four pegs 34 . 36 . 38 . 40 includes.

The grinding tools 62 . 66 are exemplary designed as a grinding wheel packages. For example, the grinding tool includes 62 different segments 200 . 202 . 204 that are designed differently. In the abrasive tools described in this disclosure 62 - 68 . 162 - 168 in particular, they may be so-called built grinding wheel packages comprising a core (carrier core) on which segments 200 . 202 . 204 are included. The core can be designed in one piece or in several parts, cf. also the DE 10 2011 102 113 A1 , In this way, on the one hand, a sufficiently stiff grinding wheel can be provided. Furthermore, the grinding wheel package is weight optimized and has only a low inertia. In addition, the design allows as a grinding wheel package in case of wear or in the event of a defect replacement of only one of the segments 200 . 202 . 204 , In this respect, further cost advantages can arise during operation.

The segments 200 . 202 . 204 are at appropriate peripheral sections 206 . 208 . 210 of the workpiece 30 customized. Accordingly, the grinding tools 62 . 66 designed primarily for plunge grinding. In other words, there is no relative movement along the X direction (lengthwise direction of the workpiece) during machining 30 ) between the workpiece 30 and the grinding tools 62 . 66 ,

In 3 illustrate with 212 . 214 designated block arrows a feed or feed drive of the grinding tools 62 . 66 in the direction of the workpiece 30 , The feed takes place along the Z-axis (feed axis). It is understood that the feed can also take place along an axis which is inclined relative to the Z-axis. This is done especially in the so-called. Schrägeinstechschleifen.

At least some of the pegs 34 . 36 . 38 . 40 the buttstock arrangement 32 include a holding section 218 , a drive 220 as well as an interface 222 for coupling to the control device 96 , The holding section 218 may include, for example, holding arms, gripping arms, jaws or the like. Preferably, the holding portion 218 designed to the workpiece 30 circumferentially at two or three defined points record. The drive 220 is preferably configured to at least one element of the holding portion 218 act. In this way, the set can 34 . 36 . 38 . 40 from the workpiece 30 be lifted off. Alternatively, it is conceivable that a holding force or biasing force with which the setter 34 . 36 . 38 . 40 on the workpiece 30 interacts, is significantly reduced. In this way, the set can 34 . 36 . 38 . 40 are moved from an attack state to a non-attack state, and vice versa.

The control device 96 is preferably with the Setzstockanordnung 32 and with the feed drives 212 . 214 coupled. In this meadow can be about a feed force with which the grinding tools 62 - 68 . 162 - 168 on the workpiece 30 act on a current state of the pegs 34 . 36 . 38 . 40 the buttstock arrangement 32 be adjusted. So it is conceivable to reduce the feed force at least for a short time, if a state change at least one of the pegs 34 . 36 . 38 . 40 is carried out.

3 further illustrates that the pegs 34 . 36 . 38 . 40 the buttstock arrangement 32 preferably on one side of the workpiece 30 arranged are the grinding tools 62 - 68 . 162 - 168 opposite. In this way, the pegs can 34 . 36 . 38 . 40 the feed force of the grinding tools 62 - 68 . 162 - 168 absorb or counteract this.

4 illustrates a partial view of a grinding machine, which is a setter 34 having, to a workpiece 30 engages that on a workpiece holder 20 is included. The buttstock 34 has a base 226 up, taking part in a guided tour 16 on the machine bed 12 the grinder is included. The base 226 carries a drive 220 as well as an interface 222 , The drive 220 of the peg 34 can be designed as a fluidic drive or as an electromechanical drive.

The buttstock 34 has a holding section 218 on. The holding section 218 of the peg 34 includes, by way of example, a first arm 228 and a second arm 230 holding a section of the workpiece 30 between them. The poor 228 . 230 can also be referred to as holding arms, gripping arms or as clamping jaws. The drive 220 is designed to be the arms 228 . 230 selectively open or close. A corresponding movement of the arms 228 . 230 is in 4 through with 232 . 234 illustrated double arrows illustrated. In this way, the set can 34 about the control device 96 (see. 3 ) are controlled to support the workpiece in an attack condition 30 attack as well as in a non-attack state from the workpiece 30 be removed or at least with a significantly reduced holding force to the workpiece 30 attack.

The in 4 shown setter 34 can also be referred to as an active setter. The active setter 34 can via the control device 96 during machining of the workpiece 30 operated at least in the attack state and in the non-attack state.

5 FIG. 3 illustrates a temporal state profile of a jig arrangement, which is approximately in accordance with FIG 3 illustrated buttstock arrangement 32 includes four pegs. A horizontal axis (abscissa) illustrates the time course (t). This in 5 The diagram shown further comprises 238 . 240 . 242 . 244 designated waveforms. The waveform 238 is assigned to a first set of pegs. The waveform 240 is assigned to a second setter. The waveform 242 is assigned to a third setter. The waveform 244 is assigned to a fourth set of pegs. The waveforms 238 . 240 . 242 . 244 each comprise two states labeled I and II. State I describes by way of example the non-attack state of the respective set. State II exemplifies the attack state.

Overall shows 5 in that, according to one exemplary embodiment, the setting sticks can be actuated offset in time, so that a phase shift between the signal curves 238 . 240 . 242 . 244 occurs. Accordingly, there is a waveform in which always at least one of the pegs is in the attack state. It is understood that the frequency or length of the states I and II shown here need not necessarily be constant. Deviating designs are conceivable, for example, depending on the actual machining task.

6 illustrates an alternative embodiment of a signal waveform for driving a Setzstockanordnung. With 248 . 250 . 252 . 254 designated signals can be assigned a total of four typesetting. In 6 the waveforms are phase locked. Accordingly, all pegs are simultaneously in the attack state or in the non-attack state.

It is understood that without further ado a mixture of the basis of the 5 and 6 can be imagined, in which approximately individual pairs of the group of pegs are phase-shifted relative to other pegs ( 5 ), wherein the sets of the pairs of phases with each other phase-synchronous ( 6 ).

As already explained above, according to an exemplary embodiment, it is provided to coordinate or synchronize the actuation of the setting sticks with the control of the feed drives of the grinding tools. In this way, about a feed force acting on the workpiece, can be reduced when a state change or status change occurs in one of the setting sticks.

In this context is further on 7 referenced, which illustrates a temporal state course of two setting sticks and this a state of a state of the delivery force descriptive signal is compared. One with 258 designated signal is assigned to a first set of pegs. One with 260 designated signal is assigned to a second setter. One with 262 designated signal describes the course of the delivery force. As already described above, the signal curves associated with the setting sticks 258 . 260 one Describe attack state and a non-attack state.

7 further illustrates by inclined flanks 264 . 266 a transitional state. With 264 designated flanks describe a transition state when switching from non-attack state I to attack state II. Mit 266 designated flanks indicate a transition state when changing from the attack state II to the non-attack state I. In the illustration according to 7 The first set of stick changes from the attack state to the non-attack state at exactly the same time the second set point changes from the non-attack state to the attack state. However, this is only to be understood as an exemplary embodiment.

7 further shows that the feed force is reduced when a state change is pending at one of the setting sticks. The in 7 illustrated relationship between Setzstockzustand and feed force can basically also in the basis of 5 and the 6 be provided illustrated signal waveforms.

For illustrative purposes, is in 7 through the waveform 262 designated feed force only qualitatively described, wherein a first state with I and a second state is denoted by II. By way of example, the state I can describe a reduced delivery force. This also includes a state where the feed force is zero. State II describes, by way of example, a maximum delivery force. It is understood that the change between the states I and II does not have to be abrupt with infinitely steep flanks. Rather, the Zustellkraft when passing between the states I and II pass through a transition region. Furthermore, it is understood that in the 5 to 7 illustrated waveforms for the control of the pegs can have a smooth overall course. The states I and II do not necessarily have to be assigned discrete values (such as open or not open). Accordingly, the state curves may also include, for example, sinusoidal or similarly smoothed curves. The same generally applies to the signal curve of the delivery force.

8th illustrated in a modified representation of the various states that can take the pegs. An example describes with 268 designated block a first set and a with 270 designated block a second set. The pegs can take a total of three states with 272 . 276 and 274 are designated. The state 272 exemplifies the non-attack state. The state 274 exemplifies the attack state. The state 276 describes a transition state. At the transition between the state 272 and the condition 274 a setter goes through the transitional state. The transition state can be used to announce the actual state change of the peg. In this way, a time window is created that allows an adjustment of the feed force. For comparison, reference is made to a traffic light in traffic. The transition state corresponds to the yellow signal, which signals a transition between the red signal and the green signal (and vice versa).

The transition state 276 can also be used when the states 272 . 276 actually understood as discrete states. Even if the buttstock - structurally, based on the attack on the workpiece - can assume only two states (such as OPEN and CLOSE), the transition state allows improved flexibility and a higher variety of functions in the control. In 8th are the two by the with 268 . 270 designated signal waveforms alternately in the attack state or in the non-attack state, wherein at the same time the transition state is traversed during the change between the states.

It is understood that in the 5 to 8th illustrated flow charts represent only examples. Based on the basic configurations illustrated by way of example, a target configuration can be derived by heuristic measures if, for example, the order, frequency or a phase offset of the signal profiles are varied. The temporal portion of the states in a period can also be varied. It is further understood that a periodically recurring sequence of states does not necessarily have to be present. Rather, depending on the current application, deviations from a strictly periodic sequence may be made.

9 illustrates a method of machining workpieces, in particular for grinding gear shafts, camshafts, drive shafts or crankshafts using a schematically simplified block diagram.

The method comprises a step S10, in which a wave-shaped workpiece is received on a workpiece spindle. The workpiece does not necessarily have to be completely rotationally symmetrical. It is also conceivable workpieces that have cams or similar eccentrically shaped contours.

A step S12 comprises providing a group of pegs which are spaced apart along an axial longitudinal extent of the workpiece. The props are preferably active Putties that can take an attack state and a non-attack state. In the attack state, the pegs supportively engage the workpiece to prevent excessive deformations, deflections or the like. In the non-attack state, the pegs are exemplary spaced from the workpiece. Alternatively, at least one holding force or supporting force with which the setting sticks engage the workpiece is reduced in the non-attack state. The setting sticks are preferably coupled to a control device of the grinding machine, which is designed to selectively control individual setting sticks or at least part sets of setting sticks.

Another step S14 relates to the provision of at least one grinding spindle, which is provided with at least one grinding tool, in particular a grinding wheel. Preferably, the grinding spindle with the grinding tool received thereon is configured for plunge grinding or for oblique plunge grinding.

This is followed by a further step S16, which includes the machining of the workpiece. Step S16 may include substeps S18, S20, S22. The step S18 includes generating a feed motion to bring the grinding tool into engagement with the workpiece. The step S20 comprises the generation of a relative rotation between the grinding tool and the workpiece, whereby the actual material-removing machining is made possible. The relative rotation between the grinding tool and the workpiece can be effected by activating a grinding spindle and / or by activating a workpiece spindle.

A further sub-step S22 of the processing step S16 relates to an activation of the group of pegs, wherein at least some pegs of the group of pegs are selectively placed in the attack state or the non-attack state. This takes place during the machining of the workpiece. This selective control of the pegs during machining can lead to higher manufacturing accuracy.

10 1 illustrates, by way of a schematically highly simplified block diagram, an exemplary embodiment of a method for driving a group of setting sticks during a machining, in particular an abrasive machining, of a workpiece.

The method comprises a step S50 which is basically based on the in 9 illustrated processing step S16 may be based. Step S50 comprises various sub-steps S52-S66 which relate, for example, to the actuation of a first setting stick (steps S52, S58, S64), a second setting stick (S54, S60, S66) and a feed drive (S56, S62).

During machining, while at least one grinding tool engages the workpiece, the setting sticks can be operated alternately in the attack state and in the non-attack state. It is understood that periods of time are conceivable in which both sets are simultaneously in the attack state or in the non-attack state. By way of example, sub-steps S52 and S54 describe a state in which the first set stick in the non-attack state and the second set stick in the attack state. A change of state of the setting sticks can be initiated via a so-called transition state. During the transient state, sub-step S56 may be followed, which includes, by way of example, a reduction in the feed force. Then the actual (structural) change of state of the pegs can take place. Accordingly, the sub-step S56 may further include increasing the feed force again. Subsequent steps S58, S60 describe a period in which, for example, the first set of pegs is in the attack state and the second peg is in the non-attack state.

Again, a transition state can follow, which is used, for example, first to reduce the feed force, to bring about the actual (structural) state change of the setting sticks, and then to raise the feed force again, cf. the sub-step S62. Again, a period may follow, in which the pegs are operated in their new states, cf. sub-steps S64 and S66, wherein the first set of stick in the non-attack state and the second set-up stick is in the attack state.

It should be understood that the state histories exemplified and described herein are the starting point of many conceivable procedures. It is essential that a plurality of setting sticks is provided, at least some of which are selectively controllable in order to operate the setting sticks alternately in an attack state and a non-attack state during the processing of the workpiece. Thus, there are active and passive phases for at least one of the pegs. Depending on a currently machined workpiece, in particular its geometry and the selected material, optimizations can be carried out, for example, by means of heuristic and / or empirical methods.

Claims (15)

Method for grinding gear shafts, camshafts or crankshafts, comprising the following steps: - receiving a wave-shaped workpiece ( 30 ) on a workpiece spindle ( 22 ), - providing a group of pegs ( 34 . 36 . 38 . 40 ), along an axial longitudinal extent of the workpiece ( 30 ) are spaced from each other, wherein the pegs ( 34 . 36 . 38 . 40 ) can assume an attack state and a non-attack state, wherein the pegs ( 34 . 36 . 38 . 40 ) in the attack state supporting the workpiece ( 30 ), - providing at least one grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) with at least one grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ), and - machining the workpiece ( 30 ), comprising: - generating a feed movement to the grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ) into engagement with the workpiece ( 30 ), - generating a relative rotation between the grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ) and the workpiece ( 30 ), and - driving the group of pegs ( 34 . 36 . 38 . 40 ) to the pegs ( 34 . 36 . 38 . 40 ) selectively in the attack state or the non-attack state, wherein during the processing, a change between the attack state and the non-attack state takes place. The method of claim 1, wherein the group of pegs ( 34 . 36 . 38 . 40 ) at least two individually controllable pegs ( 34 . 36 . 38 . 40 ), wherein during processing, at least temporarily, a first set of pegs ( 34 ) is in the attack state, while a second set ( 36 ) is in the non-attack state, and wherein during processing, at least temporarily, the first set ( 34 ) is in the non-attack state, while the second set ( 36 ) is in the attack state. Method according to claim 2, wherein the at least two pegs ( 34 . 36 . 38 . 40 ) during the machining of the workpiece ( 30 ) are operated alternately in the attack state and in the non-attack state. The method of claim 2 or 3, wherein the at least two pegs ( 34 . 36 . 38 . 40 ) are at least temporarily in the same state when the first set ( 34 ) from the attack state to the non-attack state and the second set of sticks ( 36 ) is transferred from the non-attack state to the attack state. Method according to one of claims 2 to 4, wherein at least two pegs ( 34 . 36 . 38 . 40 ) of the group of pegs are operated simultaneously in the attack state and in the non-attack state, and are switched back and forth between the attack state and the non-attack state. Method according to one of the preceding claims, wherein the pegs ( 34 . 36 . 38 . 40 ) are further operable in a transient state, the transient state describing an impending change between the attack state and the non-attack state. Method according to one of the preceding claims, wherein a feed force with which the grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ) on the workpiece ( 30 ) is reduced, if one of the pegs ( 34 . 36 . 38 . 40 ) is switched between the attack state and the non-attack state, wherein the delivery force is preferably reduced, while the set stick ( 34 . 36 . 38 . 40 ) is in a transient state that initiates a change between the attack state and the non-attack state. Method according to one of the preceding claims, wherein at least some pegs ( 34 . 36 . 38 . 40 ) of the group of pegs during processing are switched back and forth several times between the attack state and the non-attack state, wherein preferably at least two pegs ( 34 . 36 . 38 . 40 ) of the group of pegs are alternately switched back and forth between the attack state and the non-attack state. Cylindrical grinding machine ( 10 . 110 ) for grinding gear shafts, camshafts or crankshafts, comprising: - a machine bed ( 12 ), - a workpiece holder ( 20 ) with a workpiece spindle ( 22 ), - at least one grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) with a grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ), - a group of pegs ( 34 . 36 . 38 . 40 ), which are arranged spaced from each other, wherein the pegs ( 34 . 36 . 38 . 40 ) are operable in an attack state and a non-attack state, and wherein the pegs ( 34 . 36 . 38 . 40 ) are adapted, in the attack state, to support a workpiece ( 30 ), which on the workpiece holder ( 20 ), and - a control device ( 96 ), which is adapted to the pegs ( 34 . 36 . 38 . 40 ) during the machining of the workpiece ( 30 ) selectively in the attack state or the non-attack state, with a defined change between the attack state and the non-attack state, at least some of the pegs ( 34 . 36 . 38 . 40 ) of the group of pegs are designed as active pegs and with at least one buttstock drive ( 220 ) or can be coupled to form a respective set ( 34 . 36 . 38 . 40 ) optionally in the attack state or the non-attack state. Grinding machine ( 10 . 110 ) according to claim 9, wherein the control device ( 96 ) is further adapted to a feed drive of the grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) during a transition of a peg ( 34 . 36 . 38 . 40 ) between the attack state and the non-attack state, a feed force of the grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ) on the workpiece ( 30 ) to reduce. Grinding machine ( 10 . 110 ) according to claim 9 or 10, wherein the control device ( 96 ) is further adapted to the pegs ( 34 . 36 . 38 . 40 ) in a transition state, which is traversed at a change between the attack state and the non-attack state, wherein during the transition state, the grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) is controlled in particular, in particular the delivery force of the grinding tool ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ) on the workpiece ( 30 ) to control. Grinding machine ( 10 . 110 ) according to one of claims 9 to 11, wherein the at least one grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) at least one sanding disk designed as a grinding wheel package ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ), wherein the grinding wheel package has a core which is designed in several parts and has different axial sections which are joined together, and wherein the grinding wheel package comprises a plurality of abrasive segments ( 200 . 202 . 204 ), the corresponding sections ( 206 . 208 . 210 ) of the workpiece to be machined ( 30 ) assigned. Grinding machine ( 10 . 110 ) according to one of claims 9 to 12, further comprising: - a plurality of spindle units ( 50 . 52 ; 150 . 152 ), in particular two spindle units, wherein at least one of the spindle units ( 50 . 52 ; 150 . 152 ) a grinding spindle ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) with a cantilevered grinding wheel ( 62 . 64 . 66 . 68 ; 162 . 164 . 166 . 168 ), and wherein the spindle units ( 50 . 52 ; 150 . 152 ) preferably facing each other on the machine bed ( 12 ) are included. Grinding machine ( 10 . 110 ) according to one of claims 9 to 13, further comprising: - at least one spindle unit ( 50 . 52 ; 150 . 152 ), the two grinding spindles ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ), wherein the two grinding spindles ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) a common travel drive ( 86 . 88 ; 186 . 188 ), and wherein the two grinding spindles ( 54 . 56 . 58 . 60 ; 154 . 156 . 158 . 160 ) of the spindle unit ( 50 . 52 ; 150 . 152 ) alternately in an active position or a passive position with respect to the workpiece ( 30 ) are movable, in particular by a pivoting drive ( 86 . 88 ; 186 . 188 ), the spindle unit ( 50 . 52 ; 150 . 152 ) assigned. Machine control program comprising program code adapted to control a control device ( 96 ) of a cylindrical grinding machine ( 10 . 110 ) for grinding gear shafts, camshafts or crankshafts to carry out the steps of the method according to any one of claims 1 to 8, when the machine control program on the control device ( 96 ) is performed.

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