CN102695583A

CN102695583A - Method and machine tool for simultaneously machining two workpieces

Info

Publication number: CN102695583A
Application number: CN2010800511967A
Authority: CN
Inventors: 阿希姆·泛音瑙尔; 迪特尔·芬克
Original assignee: Stama Maschinenfabrik GmbH
Current assignee: Stama Maschinenfabrik GmbH
Priority date: 2009-11-12
Filing date: 2010-11-04
Publication date: 2012-09-26
Also published as: WO2011057941A1; DE102009054095A1; EP2498949A1

Abstract

The invention relates to a method for simultaneously machining at least two workpieces (22, 23) using a machine tool (10) for machining, comprising a workpiece clamping fixture for clamping workpieces (22, 23) and at least two tool spindles (15, 16) displaceable in three orthogonal machine axes (x, y, z) synchronously with each other and relative to the workpiece clamping fixture, and disposed parallel next to each other along a first (x) of the machine axes at a center distance (26) from each other, comprising the steps of: a) clamping two workpieces (22, 23) on a workpiece table (14) that can pivot back and forth at least 180 DEG about a pivot axis (24) extending perpendicular to the first machine axis (x), such that the longitudinal axes of the workpieces (22, 23) extend parallel to each other and perpendicular or at an angle to the first machine axis (x) and perpendicular to the pivot axis (24), b) machining the two workpieces (22, 23) at the same time on the same contour using machining tools (17, 18) chucked in the two tool spindles (15, 16), wherein the first workpiece (22) is machined using the first tool spindle (15) and the second workpiece (23) is machined using the second tool spindle (16), c) pivoting the workpiece table (14) by 180 DEG , and d) machining first the one and then the other workpiece (15, 16) using a single spindle, wherein the first workpiece (22); is machined using the first tool spindle (15) and the second workpiece (23) is machined using the second tool spindle (16).

Description

Method and machine tool for simultaneously machining two workpieces

Technical Field

The invention relates to a method for simultaneously machining at least two workpieces by means of a machine tool for machining, comprising a workpiece clamping device for clamping the workpieces and at least two tool spindles which are arranged in such a way that they can be moved synchronously with respect to one another and relative to the workpiece clamping device on three mutually orthogonal machine axes and are arranged parallel to one another at a mutual center distance along a first machine axis.

The invention also relates to a machine tool for simultaneously machining at least two workpieces, having a workpiece clamping device for clamping at least two workpieces and having at least two tool spindles for accommodating a machining tool, wherein the two tool spindles can be moved synchronously with respect to one another and relative to the workpiece clamping device on three mutually orthogonal machine axes and are arranged parallel to one another at a mutual center distance along a first machine axis.

Background

Such a method is known from DE10330909a1, in which a so-called double spindle machine tool is described.

The known machine tool has a spindle head with two tool spindles arranged parallel to one another, which are supported in a known manner on a table such that they can be moved relative to the workpiece on three orthogonal linear axes X, Y, Z. The tool spindles are either rigidly connected to one another or are actuated synchronously with one another.

In this way, simultaneous and contour-identical machining of two workpieces can be achieved by means of a known machine tool, which is supported on two spindles, which are fastened to a machine frame and form a workpiece clamping device.

"identical in time" (zeitgleich) is understood within the scope of the present application to mean that the processing steps on the two workpieces are carried out in parallel in time (zeitlich parallel), i.e. the same operation is carried out on both workpieces in the same time period.

In contrast to this, "simultaneously" (gleichzeitig) is understood to mean that, within the scope of one production step, two workpieces are clamped into the machine tool, are identically machined and are then released again, not all operations having to be carried out identically in time.

As with each machine tool, the known machine tools also have only a defined travel displacement in three linear axes, wherein the travel displacement, in particular in the y-axis, is limited. Generally, the travel displacement of the x-axis and z-axis of the tool feed to the workpiece is large, and thus no problem occurs in machining the workpiece.

The advantage of such double spindle machining is that both workpieces can be precisely machined in contour in the same time by means of a single actuation, so that a significantly increased yield of finished workpieces is achieved compared to single spindle machines with only a slight increase in investment costs for the double spindle machine.

A further advantage of the double spindle machine is that the workpieces can be produced in pairs matched to one another, since the influence of the temperature profile or the like on two workpieces produced identically in time is the same.

However, the known machine tool and the method implemented thereon have the disadvantage that long workpieces cannot be machined on this machine tool. These workpieces (e.g., rod material) mostly have a significantly longer dimension at one coordinate than at the other two coordinates.

Depending on the arrangement of the tool spindle parallel to the x axis, the two workpieces must likewise be arranged side by side spaced apart from one another in the x axis so that they extend in the shorter y-axis direction.

Disclosure of Invention

The object of the invention is therefore to improve the known machine tool and the known method in such a way that workpieces which, after clamping, extend in the y-axis direction over a length which is greater than the relative travel displacement between the workpiece spindle and the workpiece clamping device can be machined while maintaining a high machining precision and at a high workpiece throughput.

According to the invention, this object is achieved in a method of the aforementioned type by the following steps:

a) clamping at least two workpieces on a workpiece table which can be pivoted back and forth by at least 180 ° about a pivot axis extending perpendicularly to the first machine axis in such a way that the workpieces extend with their longitudinal axes parallel to one another and perpendicularly or obliquely with respect to the first machine axis and perpendicularly to the pivot axis,

b) two workpieces are machined with the same machining tool clamped into the two tool spindles in the same time and contour, wherein a first workpiece is machined with the first tool spindle and a second workpiece is machined with the second tool spindle,

c) swinging the workpiece table by 180 DEG, and

d) first, one workpiece is machined by a single spindle and then the other workpiece is machined by a single spindle, wherein a first workpiece is machined by a first tool spindle and a second workpiece is machined by a second tool spindle.

According to the invention, the object is also achieved by a machine tool of the type mentioned above, in which the workpiece clamping device is designed as a workpiece table which can be pivoted back and forth by at least 180 ° about a pivot axis extending perpendicularly to the first machine axis.

In modern machine tools, the workpiece clamping device is designed as a turntable, i.e. as a workpiece table which is designed to be pivotable about a pivot axis, as is used in machine tools having a working area and an assembly area, wherein the two areas are separated by an injection-molded protective wall which is arranged on the workpiece table, so that the assembly area can be assembled with the workpiece to be machined, while the workpiece is machined in the working area at the same time.

Examples for single-spindle machine tools with a turntable and an injection-molded protective wall are described in DE3533089a1, DE3734722a1 and DE4306093a 1.

The workpiece is clamped on a workpiece table, also referred to as a pendulum table, in such a way that the workpiece does not extend parallel to the x direction, wherein the workpiece extends out of the working area due to its length.

In this way, the workpiece sections located in the working area can be machined in a dual spindle manner.

After that, the workpiece table is pivoted through 180 ° about its pivot axis, so that the workpiece region, which has been pivoted into the working region and has not been machined until now, can be machined.

However, the correspondence relationship between the workpiece and the tool spindle is exchanged by the oscillation of the workpiece. The workpiece previously machined by the first tool spindle is now machined by the second tool spindle in a further double-spindle machining, the sequence of which can also be reversed.

In particular, in the case of high precision requirements, it is conceivable that the machining precision of the workpiece is reduced when a further tool spindle and its associated tool assembly are used in the machining process.

The reason for this is, on the one hand, that the tool components are slightly different and are adapted to the respective tool spindle, which is likewise different from the other tool spindle.

Furthermore, the workpiece is clamped in its corresponding relationship with the tool spindle, so that machining can be carried out with high precision only on the premise that the tool spindle and the workpiece remain in correspondence with each other.

The inventors of the present invention have also realized that single spindle machining is provided in addition to or instead of dual spindle machining, i.e. first machining a first workpiece with a corresponding first tool spindle and then machining a second workpiece with a corresponding second tool spindle, after oscillation of the workpiece table.

In this context, "single spindle machining" is understood to mean that the two tool spindles are driven synchronously each time, but only one of the two tool spindles is used on the workpiece, and the other tool spindle is driven only with it and does not machine the workpiece.

The inventors have realized that the travel displacement of the double-spindle machine tool in the x-direction, i.e. perpendicular to the longitudinal direction of the clamped workpiece, is designed to be sufficient to enable machining of a single spindle. For workpieces parallel to the y-axis, the tool spindles need only be moved in the x-direction from left to right for single-spindle machining by a distance corresponding to the distance between the two tool spindles. If the workpiece is tilted with respect to the x-axis, the travel displacement in the x-direction is designed correspondingly larger.

From the first impression, it appears to be disadvantageous because the higher machining speeds of the double-spindle machine tool are not fully utilized, which applies only to the part of the machining in which the workpieces are interchanged in their lateral position, so that a single-spindle machining is carried out.

In other words, one part of the machining is carried out double-spindle, while the other part of the machining is carried out sequentially and single-spindle. Furthermore, in the initial rotational position of the turret, each machining is carried out with double spindles, whereas after the oscillation, if a higher precision is required, the machining is carried out with a single spindle, otherwise the double spindle machining is carried out.

In this way, a combination of high machining speeds of double-spindle machines and high machining accuracy of single-spindle machines is achieved, where pendulum tables have hitherto been used.

Furthermore, the workpieces are not parallel to the x direction with the maximum travel displacement, but must have a distance from one another in the x direction, which distance the machining spindles have from one another in the x direction. If the workpiece is perpendicular to the x-axis, the travel displacement in the y-direction only determines the maximum length of the workpiece region to be machined in the rotational position of the workpiece table. But it is also possible to tilt the workpiece with respect to the x-axis, so as to increase the maximum length to be machined by √ 2, in the case of an angle of 45 °, i.e., by approximately 1.4 times.

In this way the object of the invention is perfectly achieved.

In a refinement, it is preferred to rotate the workpieces in step f) about their longitudinal axes, after which step d) is first repeated, then step c) is repeated, and then step b) is repeated.

It is advantageous here that other sides of the workpiece can be machined. By rotating about the longitudinal axis of the workpiece, the workpiece faces the tool spindle with the other side, so that after the turret has been swiveled again the correspondence between the workpiece and the tool spindle must be established again in order to be able to carry out the machining of the single spindle first before the machining of the double spindle can be carried out.

Alternatively, it is preferable to rotate the workpiece in step f) about a central axis extending parallel to the longitudinal axes of the workpiece, after which step b) is first repeated, then step c) is repeated, and then step d) is repeated.

In this rotation, the workpiece is again exchanged on its side, so that the machining is carried out first of all on the double spindle and, after the new pivoting of the turntable, on the single spindle.

It is also preferred that in step f) the workpiece is rotated about a central axis extending perpendicularly to the longitudinal axes of the workpiece and perpendicularly to the pivot axis, after which step d) is first repeated, then step c) is repeated, and then step b) is repeated.

In this rotation, the workpiece does not change its side surface, so that the machining is carried out first on a single spindle and then on two spindles after the turntable has been pivoted again.

Repeating step f) and subsequent steps until all sides of the workpiece are machined.

Accordingly, in modern machine tools, it is preferred to provide a plurality of devices on the workpiece table such that the workpiece is pivoted about its respective longitudinal axis, about a central axis extending parallel to its respective longitudinal axis or about a central axis extending perpendicular to its respective longitudinal axis.

The novel machine tool has a travel displacement in the direction of the first machine axis which is at least twice the center distance between the two tool spindles.

It is also possible to provide the new machine tool with two by two tool spindles and two turrets, so that two workpieces can be machined with two tool spindles on each turret. In other words, 4 workpieces can be processed simultaneously.

When the workpieces are clamped on a common turntable, it is also possible to machine 4 workpieces by means of two tool spindles, but a spacing is provided between each pair of two workpieces in the x direction, which is greater than the center distance of the tool spindles to one another.

In this way, in one rotational position of the turret, a first pair of workpieces is first machined double-spindle and then a second pair of workpieces is machined double-spindle. If the precision requirement permits, two pairs of workpieces can be machined side by side again in a two-spindle manner after the workpiece table has been pivoted through 180 °.

If a high degree of precision is required, all workpieces can be machined in a single spindle by means of the originally assigned tool spindle, wherein the respective empty tool is located either on the left or right side of the turret or between two pairs of workpieces, where it can be moved with the advance without work.

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

Drawings

Embodiments of the invention are illustrated in the drawings and set forth in detail in the following description. Wherein,

figure 1 shows a schematic front view of a new machine tool implementing the new method;

fig. 2 shows a schematic side view of the machine tool of fig. 1 from the left side of fig. 1;

FIG. 3 shows a top view of a workpiece table of the machine tool of FIG. 1, with a spindle shown schematically; and

fig. 4-9 show different processing stages of a workpiece clamped on a workpiece table as in the view of fig. 3.

Detailed Description

Fig. 1 shows a schematic front view of a machine tool 10, not to scale, the machine tool 10 having a spindle head 11 supported on a schematically illustrated machine frame 12.

Furthermore, a workpiece clamping device in the form of a workpiece table 14 is provided, with respect to which the spindle head 11 can be driven in the usual manner on three mutually orthogonal machine axes X, Y, Z, which are defined by coordinate axes marked next to the machine tool 10.

In the example shown, all three machine axes are realized in the spindle head 11, but it is also possible to realize one or more machine axes in the workpiece table 14.

Two

tool spindles

15, 16 are provided in the spindle head 11, each of which can accommodate a

respective machining tool

17, 18, which is driven in rotation about its own axis of

rotation

19, 21.

In this way, the two

workpieces

22, 23 clamped to the workpiece table 14 can be machined with the

tool spindles

15, 16 identical in time and contour to one another.

It is also possible to provide two sets of

tool spindles

15, 16 and one second workpiece table 14 in the machine tool 10, so that 4 workpieces can be machined simultaneously.

The workpiece table 14 is designed as a turntable and can be pivoted about its vertically extending pivot axis 24, which is indicated by an arrow 25.

The machine tool shown in the figures is designed as a vertical machine, with the

tool spindles

15, 16 oriented vertically. It is also possible to design the new machine tool as a horizontal machine with the

tool spindles

15, 16 lying flat, which does not lose the advantages of the new method. Here, the workpiece table 14 can rotate about a horizontal pivot axis.

The pivoting of the workpiece table 14 is used in the prior art described above to move the workpiece from the working area of the machine tool into the installation area and vice versa. For this purpose, an injection-molding protective wall is usually provided, which divides the workpiece table 14 into a working region facing the spindle and an installation region facing away from the spindle.

In the case of the new machine tool 10, no injection-molded protective wall of this type is provided, so that the method according to the invention can be carried out on the new machine tool, as will be explained in more detail below with reference to fig. 3 to 9.

The two axes of

rotation

19, 21 of the

tool spindles

15, 16 have a spacing 26 from one another. The two

workpieces

22 and 23 are also spaced apart from one another in the x-axis by this distance 26 when they run parallel to one another in the y-axis.

In the side view of fig. 2, a workpiece 22 can be recognized, which has a longitudinal extent in the direction of the y axis, which is dimensioned such that the workpiece 22 cannot be machined completely in the illustrated clamping along the y axis.

For the sake of clarity, fig. 2 shows the outermost position of the spindle head 11' in the y-direction by means of a dashed line. The tool spindle 15 'on the left in fig. 1 and the accommodated tool 17' are likewise shown in dashed lines.

The boundary line of the working space of the machine tool 10 is shown in dotted lines 27 on the extension of the tool 17'.

In other words, to the left of the line 27 in fig. 2 is a working area 27' in which the workpiece 22 can be machined. The region 27 "to the right of the line 27 cannot be machined, at least in the clamping shown in fig. 2.

The situation of fig. 2 is again schematically illustrated in fig. 3, in which the workpiece table 14 is shown in a plan view, so that two

workpieces

22 and 23 can be identified, which with their regions 28 and 29 to be machined are located above the working space boundary 27, so that these regions 28 and 29 can be machined with the

tool spindles

15, 16, which are also schematically illustrated.

In the drawing, the

workpieces

22, 23 are parallel to the y-axis, but they are also arranged at an angle inclined to the x-axis, so that the length of the regions 28, 29 to be machined in the rotated state of the workpiece table 14 is extended according to the angle.

After the end of the machining operation according to fig. 3, the workpiece table 14 is pivoted through 180 ° about its pivot axis 24 by the arrow 25, so that the state of fig. 4 is reached, in which the

unmachined regions

31 and 32 of the

workpieces

22 and 23 are located above the working space boundary 27 and can now be machined by the

tool spindles

15 and 16.

In the machining process carried out according to fig. 3, the

workpieces

22 and 23 are machined by the

tool spindles

15 and 16, which are rigidly connected to one another, in the same time and in the same contour, whereas in the machining after the oscillation as shown in fig. 4, a transition is made from the double-spindle machining to the single-spindle machining.

Although this appears to be disadvantageous at first time, a significant advantage in accuracy is obtained when the workpiece 22 is always machined with the tool spindle 15 and the workpiece 23 is always machined with the tool spindle 16.

The problem of accuracy not only relates to the correspondence between the clamping of the workpiece and the respective tool spindle, but also to the tool to be reused, the running accuracy and other settings of the tool spindle.

In other words, when a workpiece is always machined with the same tool spindle in all clamping operations, i.e. always with the same tool, the machining accuracy is significantly higher overall than when two work spindles alternately machine a workpiece.

The results thus obtained are shown in fig. 5 and 6.

As shown in fig. 5, the

tool spindles

15 and 16 are first moved in the x direction, so that a region 32 of the workpiece 23 is machined by the tool spindle 16. This is shown in fig. 5.

The tool spindles 15 and 16 are then moved in the x-axis direction, so that the region 31 of the workpiece 22 is now machined by the tool spindle 15. This situation is shown in fig. 6.

In order to be able to implement these driving situations, the

tool spindles

15, 16 must only be able to travel approximately to the left and to the right with a predetermined distance 26 between them relative to the workpiece table 14. This applies to the case where the

workpieces

22, 23 are parallel to the y-axis. In contrast, if the workpiece is arranged at an angle, the travel range in the x direction must be greater depending on the angle.

When machining with one of the two

tool spindles

15, 16, the other is "free" and does not work as it travels.

In fig. 4 to 6, the machined regions of the

workpieces

22 and 23 are also shown shaded, while the regions to be machined are not shown shaded. 34 mark an overlap region which can be machined in two pivot positions of the workpiece table 14 (which correspond on the one hand to fig. 3 and on the other hand to fig. 4 to 6), so that the connection (Anschluss) between the two

regions

28 and 31 or 29 and 32 can be machined with the required precision.

In the method described above, two workpieces can be machined in a double spindle machine (e.g., machine tool 10) in part in time and contour-identical fashion, while the

regions

31 and 32 of the

workpieces

22 and 23 that are inaccessible during clamping reach the working region after the table 24 has been pivoted by 180 ° and are machined there again by the tool spindle (which was previously also machined). This means that one stage of the machining is carried out single spindle, i.e. sequentially first with the tool spindle 15 and then with the tool spindle 16.

If it is also necessary to machine the

workpieces

22 and 23 on their underside, the

workpieces

22 and 23 can be clamped to the rotary table. As shown in fig. 6, the workpiece 22 is supported on its end faces on circular tables 35 and 36, by means of which the workpiece 22 can be pivoted about its longitudinal axis 37.

The rotary tables 35 and 36 can also be identified in fig. 1.

Accordingly, the workpiece 23 is clamped on its end face into the rotary tables 38 and 39, and the workpiece 23 can be pivoted about its longitudinal axis 41 by the rotary tables 38 and 39.

The result of this wobbling is shown in fig. 7, where the

workpieces

22 and 23 are always in a "side swap" (seitenvertauscht) state, so that dual spindle machining is not possible to achieve the corresponding accuracy. Thus, the single spindle machining is performed again.

Accordingly, according to fig. 7, the workpiece 22 is first machined with the tool spindle 15, and then, according to fig. 8, the workpiece 23 is machined with the tool spindle 16. The workpiece table 14 is then swiveled about its pivot axis 24, which is indicated by the arrow 25.

The situation in fig. 9 is obtained, in which the

workpieces

22 and 23 are again in the "side-correctly" side-by-side position, so that the not yet machined (unshaded)

regions

42, 43 can now be machined by the

tool spindles

15 and 16 in the same time and contour.

It is of course also possible to machine the other sides of the

workpieces

22 and 23 in such a way that the

workpieces

22, 23, after machining their second longitudinal side, are pivoted again about their longitudinal axes 37, 41, wherein the sequence of double-spindle machining and single-spindle machining described above is repeated accordingly.

Of course, it is possible to oscillate the two

workpieces

22 and 23 not individually about their longitudinal axes 37, 41. The

workpieces

22 and 23 can also be pivoted jointly about a central axis 44 shown in fig. 9, which intersects the pivot axis 24.

If the pivoting according to fig. 9 takes place about a longitudinal axis 44 parallel to the y-axis, the

workpieces

22, 23 are again exchanged on their sides, so that the double-spindle machining takes place again immediately after the single-spindle machining. After the workpiece table 14 has been pivoted about its pivot axis 24, the single-spindle machining is again set.

Alternatively, the two workpieces can also be pivoted together about a central axis 45 extending perpendicularly to the longitudinal axes 37, 41 and perpendicularly to the pivot axis 24, i.e. about the x-axis, so that they do not change their lateral position relative to one another. Then, after the single-spindle machining according to fig. 6, the single-spindle machining is first carried out again. Thereafter, the workpiece table 14 is rotated, and the process continues with dual spindle machining.

Claims

1. A method for simultaneously machining at least two workpieces (22, 23) by means of a machine tool (10) for machining, the machine tool (10) having a workpiece clamping device for clamping the workpieces (22, 23) and at least two tool spindles (15, 16), the tool spindles (15, 16) being movable synchronously with one another and relative to the workpiece clamping device on three mutually orthogonal machine axes (x, y, z) and being arranged parallel side by side along a first machine axis (x) at a mutual center distance (26), having the following steps:

a) clamping at least two workpieces (22, 23) on a workpiece table (14), wherein the workpiece table (14) can be pivoted back and forth at least 180 DEG about a pivot axis (24) extending perpendicularly to the first machine axis (x) in such a way that the workpieces (22, 23) extend with their longitudinal axes (37, 41) parallel to one another and perpendicularly or obliquely with respect to the first machine axis (x) and perpendicularly to the pivot axis (24),

b) two workpieces (22, 23) are machined with the same machining tools (17, 18) clamped into the two tool spindles (15, 16) in a temporally identical and contour-identical manner, wherein a first workpiece (22) is machined with the first tool spindle (15) and a second workpiece (23) is machined with the second tool spindle (16),

c) swing the workpiece table (14) by 180 DEG, and

d) firstly, one workpiece (15, 16) is machined in a single-spindle manner, and then the other workpiece (15, 16) is machined in a single-spindle manner, wherein a first workpiece (22) is machined by means of a first tool spindle (15) and a second workpiece (23) is machined by means of a second tool spindle (16).

2. Method according to claim 1, characterized in that in step f) the work pieces (22, 23) are rotated about the longitudinal axes (37, 41) of the work pieces (22, 23), respectively, after which step d) is first repeated, then step c) and then step b) are repeated.

3. A method as claimed in claim 1, characterized in that in step f) the workpiece (22, 23) is rotated about a central axis (44) which extends parallel to the respective longitudinal axis (37, 41) of the workpiece (22, 23), after which step b) is first repeated, then step c) and then step d) are repeated.

4. A method as claimed in claim 1, characterized in that in step f) the workpiece (22, 23) is rotated about a central axis (45) which runs perpendicular to the respective longitudinal axis (37, 41) of the workpiece (22, 23) and perpendicular to the pendulum shaft (24), after which step d) is first repeated, then step c) and then step b) is repeated.

5. The method of any one of claims 2 to 4, wherein said step f) and subsequent steps are repeated for machining other sides of the workpiece.

6. Method according to one of claims 1 to 5, characterized in that two workpieces (22, 23) are machined at least twice with a set of two tool spindles (15, 16), wherein each two workpieces are clamped on a workpiece table.

7. A machine tool for the simultaneous machining of at least two workpieces (22, 23), having a workpiece clamping device for clamping the at least two workpieces (22, 23) and having at least two tool spindles (15, 16) for receiving machining tools (17, 18), the two tool spindles (15, 16) being movable synchronously with one another and relative to the workpiece clamping device on three mutually orthogonal machine axes (x, y, z) and being arranged parallel side by side along a first machine axis (x) at a mutual center distance (26), characterized in that the workpiece clamping device is designed as a workpiece table (14), the workpiece table (14) being pivotable to and fro by at least 180 ° about a pivot axis (24) extending perpendicularly to the first machine axis (x).

8. Machine tool according to claim 7, characterized in that a plurality of devices (35, 36, 38, 39) are provided on the workpiece table (14) for pivoting the workpieces (22, 23) about their respective longitudinal axes (37, 41), about a central axis (44) running parallel to their respective longitudinal axes (37, 41) or about a central axis (45) running perpendicular to their respective longitudinal axes (37, 41).

9. A machine tool according to claim 7 or 8 having a travel displacement in the direction of the first machine axis which is at least twice the centre-to-centre distance.

10. Machine tool according to any one of claims 7 to 9, wherein at least two further tool spindles (15, 16) and at least one further workpiece table (14) are provided.