EP2408592A1

EP2408592A1 - Machine tool and method for machining workpieces

Info

Publication number: EP2408592A1
Application number: EP10707814A
Authority: EP
Inventors: Bernhard Pause
Original assignee: MAG Europe GmbH
Current assignee: MAG IAS GmbH Eislingen
Priority date: 2009-03-16
Filing date: 2010-02-03
Publication date: 2012-01-25
Also published as: DE102009013067A1; DE202010018053U1; WO2010105717A1

Abstract

The invention relates to a machine tool (1) for multi-station machining of workpieces (2), wherein at least working spindle (5) is disposed on a spindle carrier (4) pivotable about a pivot axis (6) extending in a vertical Z direction and is vertically linearly displaceable. The at least one working spindle (5) is also displaceable along a circular arc by pivoting the spindle carrier (4). A plurality of machining stations (23, 24, 25) is disposed along the circular arc. A control unit provided for machining the workpieces (2) is designed such that the at least one working spindle (5) can be positioned along the circular arc by pivoting the spindle carrier (4) during machining of the workpieces (2), wherein at most two working spindles (5) are disposed on the spindle carrier (4). The machine tool (1) is constructed simply and allows multi-station machining of workpieces (2).

Description

Machine tool and method for machining workpieces

The invention relates to a machine tool for machining workpieces according to the preamble of claim 1. Furthermore, the invention relates to a corresponding method for machining workpieces.

From EP 0 985 487 A2 a machine tool with a spindle drum is known, on which a plurality of working spindles are arranged hanging. The spindle drum can be rotated around a vertical axis so that workpieces to be machined can be processed at several processing stations. In addition, a loading and unloading station is provided so that the work spindles can pick up the workpieces to be machined independently and store them again after processing. The workpieces to be processed pass through a machining cycle in the machine tool and are brought from one machining position to the next machining position by pivoting the spindle drum. In the respective machining position, the spindle drum is fixed, so that the machining of the workpieces can take place. A disadvantage of the known machine tool is that the spindle drum together with the work spindles represent a large mass to be accelerated and braked, so that high forces act during acceleration and deceleration and the machine tool accordingly has to be of solid construction.

From DE 101 53 807 Al a machine tool is known in which one or more work spindle units are arranged suspended on a bridge unit. The bridge unit can be pivoted about a vertical axis, so that the work spindle unit or working spindle unit units can be arranged within different processing sectors. Each work spindle unit is movable relative to the vertical axis in the radial direction and in the vertical direction on the bridge unit. A disadvantage of the known machine tool that their structure is complex due to the bridge unit with the radially movable work spindle units.

The invention is therefore an object of the invention to provide a machine tool for multi-station machining of workpieces, which is simple and therefore inexpensive to produce.

This object is achieved by a machine tool having the features of claim 1. Because at most two work spindles are arranged on the spindle carrier, the spindle carrier can be made much simpler, so that the mass to be accelerated and braked is small. The entire structure of the machine tool can be simplified thereby. In addition, by virtue of the design of the control unit, the pivot axis can be used not only to move the respective work spindle from one machining position to the next machining position, but also to position the workpiece to be machined relative to a tool. The pivot axis of the spindle carrier is thus a complete rotary machining axis (C axis). This makes it possible to simplify the processing stations since linear infeed axes required in the prior art can be omitted. While in the prior art in a turning of the workpiece, the tool had to be delivered to the workpiece located in the fixed processing position, the workpiece is now delivered by pivoting the spindle carrier about the pivot axis to the tool located in a fixed position. There- in that at most two work spindles are arranged on the spindle carrier, the machining of at most two workpieces is to be coordinated during pivoting of the spindle carrier, which is possible through a corresponding configuration of the control unit and the processing stations. For multi-station machining of a workpiece thus only the numerically controlled pivot axis (C-axis) of the spindle carrier and the numerically controlled linear axis (z-axis) for moving the respective work spindle in the z-direction is required.

Due to the fact that the spindle axis can be positioned exclusively by pivoting the spindle carrier in the horizontal x-direction and the horizontal y-direction, ie along the circular arc, the machining of a workpiece on a linearly non-movable processing station is effected exclusively by the numerically controlled pivot axis (C -Axis) of the spindle carrier and / or the numerically controlled linear axis (z-axis), which is provided by the linear movability of the work spindle in the z-direction.

Characterized in that the pivot axis is a full-fledged machining axis, a variety of processing steps with simple structure processing stations are possible, which are not linearly movable, ie fixed in any linear direction, are arranged on the base frame. As a result, linear machining axes for advancing the tools can be saved.

For positioning the workpieces during machining, the control unit is designed such that a coordinate transformation from a Cartesian coordinate system into a polar coordinate system can be carried out. Linear machining coordinates, such as linear turning paths, can thus be converted by means of the control unit into polar coordinates, with which the control unit then controls the pivoting of the spindle carrier. Because the respective work spindle is arranged suspended on the spindle carrier, the possibility of independent workpiece supply and removal ("pick-up function") remains unrestricted.The spindle carrier can preferably be swiveled through 360 °, so that a For machining shaft-shaped workpieces, a tailstock with an axis of rotation running in the z-direction can be arranged on the base frame By swiveling the spindle carrier, the wave-shaped workpiece received in the work spindle can be arranged vertically aligned with the tailstock and by moving the work spindle in the z-direction on a centering point of the tailstock so that machining of the wave-shaped workpiece can take place.

A machine tool according to claim 2 allows a simple independent supply and removal of workpieces.

A base frame according to claim 3 allows a simple lateral arrangement of the stations on the base frame or on the sides of the base frame.

A machine tool according to claim 4 allows easy feeding and removal of workpieces from one side.

A machine tool according to claim 5 allows a workpiece flow through the machine tool. A machine tool according to claim 6 allows the arrangement of a plurality of stations on the base frame. This is particularly advantageous when arranged on the common side of the base frame, a first, linearly non-movable processing station and a second, in at least one horizontal direction, ie in the x and / or y-direction, movable second processing station is. In this case, the simultaneous machining of a workpiece with two tools or processing stations can follow. The pivoting of the workpiece due to machining with the tool of the first processing station can be compensated by a linear method of the tool of the second processing station.

A machine tool according to claim 7 allows a fast and high-precision pivoting of the spindle carrier. Due to the gearless direct drive, the workpiece to be machined can be positioned with high precision during its machining by pivoting the spindle carrier relative to the tool. This is particularly advantageous if the tool or the associated processing station is not linearly movable, so that the positioning of the workpiece in the horizontal x and y direction takes place exclusively by pivoting the spindle carrier. In addition, the direct drive allows quick pivoting of the spindle carrier. This is favored by the relatively low mass of the spindle carrier to be accelerated and braked. Such direct drives are referred to as torque motors. In addition, the method of at least one work spindle can be done by a z-linear direct drive.

A machine tool according to claim 8 is inexpensive to produce. A machine tool according to claim 9 is simple and inexpensive and allows the machining of two workpieces.

A machine tool according to claim 10 ensures high flexibility in the machining of two workpieces. During the machining of a workpiece, for example, another workpiece can be picked up or stored. Furthermore, two workpieces can be processed simultaneously.

A machine tool according to claim 1 1 is extremely simple in construction, since none of the processing stations has linear machining axes.

A machine tool according to claim 12 ensures a high flexibility in the processing of the workpieces. If two workpieces are processed simultaneously, the unwanted pivoting of one workpiece due to the processing of the other workpiece can be compensated by a linear process of the tool turret. In addition, workpieces can be processed in a wavy manner by the method in the x and z directions.

A machine tool according to claim 13 allows machining of the workpieces with a rotary-driven tool. The counter spindle is preferably fixedly arranged in any linear direction on the base frame. In particular, a polygon machining of the workpieces is possible with the counterspindle. To form a polygonal shape, a machining tool for turning machining is clamped in the counterspindle. The workpiece and the tool rotate at a speed difference, wherein by pivoting the spindle carrier a Center axis offset between the spindle axis and the counter spindle axis is generated. The center axis offset corresponds to the secant of the circular arc returned by the pivoting. With regard to the bases for the production of workpieces with a polygonal shape, reference is made to EP 0 907 458 B2 (corresponding to US Pat. No. 6,761,096 B1).

A machine tool according to claim 14 ensures a high flexibility in the machining of the workpieces. If two workpieces are processed simultaneously, the unwanted pivoting of one workpiece due to the machining of the other workpiece can be compensated by a linear process of the tool holder. In addition, a twist-free rotation is possible with a corresponding arrangement of a turning tool. Due to the linear movability of the tool holder horizontally in the direction of the at least one work spindle, the chip thickness can be adjusted during spin-free rotation and / or the

Rotary tool for another subsequent rotation can be adjusted. In addition, different rotational diameters, ie paragraphs in the workpiece, can be generated by the linear movability. Preferably, the tool holder is movable in a horizontal y-direction that is substantially perpendicular to the x and z directions.

The invention is further based on the object to provide a method for multi-station machining of workpieces, which can be carried out with a simply constructed machine tool.

This object is achieved by a method having the features of claim 15. The advantages of the method according to the invention correspond to those of the machine tool according to the invention. Especially the method according to the invention can also be developed according to the features of claims 2 to 14.

Further features, details and advantages of the invention will become apparent from the following description of several embodiments. Show it:

1 is a perspective view of a machine tool according to a first embodiment,

2 is a plan view of the machine tool in Fig. 1,

3 is a perspective view of a machine tool according to a second embodiment,

4 is a plan view of the machine tool in Fig. 3,

5 is a perspective view of a machine tool according to a third embodiment,

6 shows a partially sectioned side view of the machine tool in FIG. 5 during the machining of a workpiece, FIG.

7 shows a side view of the machine tool in FIG. 5 in the region of a work spindle, FIG.

8 is a perspective view of a machine tool according to a fourth embodiment, 9 is a plan view of the machine tool in Fig. 8, and

10 is a perspective view of a machine tool according to a fifth embodiment.

Hereinafter, a first embodiment of the invention will be described with reference to Figures 1 to 2.

A machine tool 1 for multi-station machining of workpieces 2 has a base frame 3, on which a spindle carrier 4 with a work spindle 5 is arranged. The spindle carrier 4 is arranged pivotably about a pivot axis 6 extending in a vertical z-direction on the base frame 3, so that a spindle axis 6 radially spaced and parallel spindle axis 7 of the work spindle 5 along a circular arc 8 is movable. For pivoting the spindle carrier 4, a pivoting drive 9 designed as an electric drive motor is arranged on the base frame 3.

The spindle carrier 4 is cam-shaped and has a planar support wall 10, on which two z-guide rails 11 extending parallel to each other in the z-direction are arranged. On the work spindle 5 suitably trained z-guide shoes 12 are arranged so that the work spindle 5 by means of a z-drive 13 in the z-direction is linearly movable. The z-drive 13 may be designed as an electric drive motor with a ball screw - as shown in Figure 1 - or hydraulically.

The work spindle 5 is arranged in a suspended manner on the spindle carrier 3 and, on a front side facing the base frame 3, has a workpiece holder. Clamping device 14, which is rotatably driven by means of an electric spindle drive motor 15 about the spindle axis 7.

The base frame 3 is - viewed in a plan view of FIG. 2 - formed as a quadrangle and has four side walls, which are designated in detail with 16 to 19. On the first side wall 16, a supply station 20 is arranged in the form of a conveyor belt, so that the workpieces 2 in a - shown in Fig. 2 - feed position can be brought, which lies on the circular arc 8. In a corresponding manner, a discharge station 21 in the form of a conveyor belt is arranged on the opposite third side wall 18, so that the workpieces 2 can be brought into a discharge position along the circular arc 8 (shown in FIG. 2). When viewed in a direction of rotation 22, three processing stations are arranged along the circular arc 8 on the base frame 3 between the supply station 20 and the discharge station 21. A first processing station 23 is arranged on one of the first side wall 16 facing the end of the second side wall 17. Accordingly, a second processing station 24 at one of the third side wall 18 facing the end of the second side wall 17 is arranged. A third processing station 25 is disposed between the second processing station 24 and the discharge station 21 on the third side wall 18.

The first processing station 23 is designed as a first tool turret 27 arranged on a cross slide 26. The cross slide 26 has one in the z-direction by means of a z- drive motor 28 on Z-

Guide rails 29 movable z-carriage 30 on. On the z-slide 30, a x-slide 33, which is movable in a horizontal x-direction on x-guide rails 31 by means of an x-drive motor 32, is arranged on which the first tool turret 27 is fastened. The first tool turret Ver 27 has a first turret disk 36 rotatable about a first turret axis of rotation 34 by means of a first turret drive motor 35. The first turret axis of rotation 36 extends in the x direction. At the first turret disk 36 several tools 37 are arranged radially and frontally.

The second processing station 24 is designed as a second tool turret 38, which is not linearly movable, that is, in any direction fixed to the base frame 3 is arranged. The second tool turret 38 has a second turret axis of rotation 39 which is congruent with the first turret axis of rotation 34 and about which a second turret plate 40 can be driven in rotation by means of a second turret drive motor 41. The turret axes of rotation 34, 39 extend - viewed in a plan view according to FIG. 2 - in each case tangentially to the circular arc 8. In the second turret disk 40, several tools 37 are arranged radially and frontally.

The third processing station 25 is designed as a counter spindle 42, which is rotatably drivable by means of a counter spindle drive motor 43 about a counter spindle axis 44 running in the z direction. In the counter spindle 42 designed as a grinding wheel tool 37 is arranged. As an alternative to the grinding wheel, a drilling or milling tool or a multi-spindle head can be arranged in the counter spindle 42. The counter spindle 42 is not linearly movable, so fixed in any direction, arranged on the base frame 3. The counter spindle axis 44 is - viewed in a plan view according to FIG. 2 - on the circular arc. 8

For controlling the processing, the machine tool 1 has a control unit 45. The control unit 45 is designed such that during machining of the workpieces 2, the spindle axis 7 along the circular arc 8 is positionable by pivoting the spindle carrier 4, so that a recorded in the workpiece clamping device 14 workpiece 2 is positioned relative to the respective tool 37 with sufficient for processing accuracy relative. For this purpose, a coordinate transformation is implemented in the control unit 45, so that linear machining coordinates present in a Cartesian coordinate system can be converted into polar coordinates of a polar coordinate system with which the pivoting of the spindle support 4 can be controlled by means of the pivoting drive 9. The Cartesian coordinate system is formed, for example, by the x-direction, the z-direction and a horizontal y-direction.

Hereinafter, the operation of the machine tool 1 will be described. For picking up a workpiece 2 to be machined, the spindle carrier 4 is first pivoted into the feed position, where the work spindle 5 moves downwards in the z direction and the workpiece 2 is picked up by means of the workpiece clamping device 14. Subsequently, the work spindle 5 is again moved in the z direction upwards and the spindle carrier 4 is pivoted in the direction of rotation 22 in such a way that the work spindle 5 is arranged between the first and second processing stations 23, 24. This is shown in FIGS. 1 and 2. The work spindle 5 is lowered for machining the workpiece 2 in the z-direction in a first processing position. In this machining position, the workpiece 2 is machined with the tools 37 of the mutually facing tool turrets 27, 38. The processing by means of the processing stations 23, 24 can take place successively or simultaneously. Processing steps are, for example, drilling or turning.

The delivery of the workpiece 2 to the corresponding tool 37 of the second tool turret 38 takes place - as far as for the processing step not only a linear infeed in the z-direction is sufficient - by pivoting the spindle carrier 4 about the pivot axis 6. The spindle axis 6 is thus a numerically controlled machining axis of the machine tool 1. For advancing or positioning of the workpiece 2 are in the Cartesian coordinate system present linear machining coordinates by means of the control unit 45 converted into polar coordinates and controlled by means of this, the pivoting of the spindle carrier 4 such that the workpiece 2 is positioned during its machining relative to the stationary tool 37. If the workpiece 2 is machined simultaneously with a tool 37 of the first tool turret 27, the pivoting of the spindle carrier 4, which is undesirable for this machining, can be compensated by the linear traversability of the first tool turret 27 in the x-direction and / or z-direction. In addition, a wave-shaped turning of the workpiece 2 is possible by means of the first processing station 23.

The pivot axis 6 (C axis), the linear axis of the work spindle 5 (z axis) and the linear axes (x and z axis) of the first processing station 23 thus provide four processing axes, so that a simultaneous processing of the workpiece 2 with two tool cutting is possible. The first tool turret 27 is thereby tracked the feed movements about the pivot axis 6 and along the spindle axis 7. As a result, a high productivity in the machining of the workpieces 2 is possible.

The numerically controlled pivot axis 6 is also referred to as C-axis. After machining in the first processing position, the work spindle 5 is raised and the spindle carrier 4 is pivoted in the direction of rotation 22 to the third processing station 25, where the workpiece 2 is machined in a second processing position. By means of the counter spindle 42 designed as a grinding wheel tool 37 is rotationally driven and the workpiece 2 processed.

After this processing, the work spindle 5 is raised and the spindle carrier 4 is pivoted in the direction of rotation 22 in the discharge position, where the work spindle 5 is lowered and the finished workpiece 2 is deposited on the discharge station 21.

Subsequently, the spindle carrier 4 is again pivoted into the feed position, where by means of the workpiece clamping device 14, the next workpiece to be machined 2 is received. The pivoting in the feed position can be done either in the direction of rotation 22, so that the spindle carrier 4 is pivoted along the circular arc 8 by 360 °, or against the direction of rotation 22, so that the spindle carrier 4 is pivoted only along part of the circular arc 8.

Hereinafter, a second embodiment of the invention will be described with reference to Figures 3 and 4. Structurally identical parts are given the same reference numerals as in the first exemplary embodiment, to the description of which reference is hereby made. Structurally different but functionally similar parts receive the same reference numerals with a following a. In contrast to the first exemplary embodiment, the transport station designed as a conveyor belt 21a is arranged adjacent to the feed station 20 on the first side wall 16. In addition, the pivoting drive 9a is a direct drive engine formed, which is connected to the pivoting of the spindle carrier 4 gearless with this. Such a direct drive motor is also referred to as a torque motor. Accordingly, the z-drive 13a is designed as a linear direct drive motor, so that the work spindle 5 without a ball screw is electrically movable in the z-direction.

Furthermore, the first processing station 23a is designed as a second counterspindle 46, which can be driven in rotation about a second counter spindle axis 47 running in the z direction by means of a second counter spindle drive motor 48. The second counter spindle axis 47 is - viewed in a plan view according to Figure 4 - on the circular arc 8. The second counter spindle 46 is not linearly movable, so fixed in any direction, arranged on the base frame 3.

After receiving a workpiece to be machined 2 is the

Spindle carrier 4 is pivoted about the pivot axis 6 to the first processing station 23a and lowered the work spindle 5 in the z-direction in a first processing position. By means of the first processing station 23a is a turning of the workpiece 2, wherein this is provided with a polygonal inner or outer contour. For this purpose, the work spindle 5 and the second counter spindle 46 are rotationally driven in a uniform direction of rotation 49 about their respective spindle axes 7, 47 with a speed difference. To generate a polygonal shape, a center-axis offset between the spindle axis 7 and the fixed second counter-spindle axis 47 is generated by pivoting the spindle carrier 4. The calculation of the respectively required center axis offset takes place by means of the control unit 45, which converts the linear processing coordinates into corresponding polar coordinates and controls or regulates the pivoting of the spindle carrier 4 with them. Regarding the basics of Production of workpieces 2 with a polygonal shape is referred to EP 0 907 458 B2 (corresponding to US Pat. No. 6,761,096 Bl).

After the polygon machining of the workpiece 2, this is pivoted by pivoting the spindle carrier 4 in a second processing position to the second processing station 24 and then in a third processing position to the third processing station 25, where the workpiece 2 in the manner already described is processed. Subsequently, the workpiece 2 is brought by pivoting the spindle carrier 4 in the discharge position and stored in this on the discharge station 21 a. The spindle carrier 4 can be pivoted for this purpose in the direction of rotation 22 or counter to the direction of rotation 22. For receiving the next workpiece 2 to be machined, the spindle carrier 4 is pivoted in the direction of rotation 22 into the feed position. With regard to the further mode of operation, reference is made to the description of the first exemplary embodiment.

Hereinafter, a third embodiment of the invention will be described with reference to Figures 5 to 7. Structurally identical parts are given the same reference numbers as in the previous ones

Embodiments, to the description of which reference is hereby made. Structurally different, but functionally similar parts receive the same reference numerals with a trailing b. In contrast to the preceding embodiments, the first processing station 23b is designed as a tool holder 50, which can be moved linearly in the y direction by means of a y drive motor 51 on y guide rails 52. The tool holder 50 is thus movable in the direction of the work spindle 5. A rotary tool 53 is arranged in the tool holder 50, the straight-line cutting edge 54 of which runs in a yz projection plane formed by the y and z directions parallel to the spindle axis 7 (see FIG. and z direction formed xz projection plane obliquely at an acute angle α to the spindle axis 7 (see Fig. 7).

By means of the first processing station 23b a spin-free rotation of the workpiece 2 is possible. For this purpose, the workpiece 2 is brought in the manner described in the first processing position and rotationally driven by means of the work spindle 5 with a suitable rotational speed. Subsequently, the tool holder 50 is positioned radially to the spindle axis 7 in the y-direction. For twist-free rotation of the workpiece 2, the tool holder 50 is held in the desired y-position. During spin-free rotation, there is thus no movement of the tool holder 50 in the y-direction. Due to the inclination of the cutting edge 54, this comes in sections in the direction of rotation 22 in engagement with the workpiece 2 during pivoting of the spindle carrier 4, whereby a turning of the workpiece 2 over the desired length in the main borrow without twist is possible. Without swirl means that feed marks around the spindle axis 7, ie about the z-axis of the workpiece 2, have a slope of 0 °. The twist-free rotation can be avoided in a variety of workpieces 2 post-processing. The process of the tool holder 50 in the y-direction is used to set a chip thickness during spin-free rotation or to readjust the cutting edge 54 for a subsequent turning operation. Furthermore, 50 different rotational diameters can be generated by the method of the tool holder. The pivoting of the spindle carrier 4 is controlled or regulated in the manner described by means of the control unit 45. With regard to the further processing of the workpiece 2, reference is made to the preceding embodiments.

Hereinafter, a fourth embodiment of the invention will be described with reference to FIGS. 8 and 9. Structurally identical parts receive the same reference numerals as in the previous embodiments, the description of which reference is hereby made. Structurally different, but functionally similar parts receive the same reference numerals with a c. In contrast to the preceding embodiments, a second work spindle 55 is arranged on the spindle carrier 4c in addition to the first work spindle 5. The second work spindle 55 is formed corresponding to the first work spindle 5. The work spindles 5, 55 are independently movable in the z-direction. The spindle axes 7 of the working spindles 5, 55 close with respect to the pivot axis 6 a first

Offset angle φi, which corresponds to a second offset angle φ ₂ between the feed station 20 and the discharge station 21c and the first processing station 23 and the second processing station 24. With the machine tool Ic a simultaneous machining of two workpieces 2 is possible. First, the spindle carrier 4c is pivoted such that the first work spindle 5 is in the feed position and the second work spindle 55 is in the discharge position. By means of the first work spindle 5, a first workpiece 2 to be machined is received. If a finished workpiece 2 is received in the second work spindle 55, it can be deposited simultaneously on the removal station 21c. Subsequently, the spindle carrier 4c is pivoted such that the second work spindle 55 is in the feed position, where it receives a second workpiece 2 to be machined. Subsequently, the spindle carrier 4c is pivoted so that the first work spindle 5 is in the second machining position and the second work spindle 55 is in the first machining position. This is shown in FIGS. 8 and 9. The two workpieces 2 can now be processed by means of the first processing station 23 and the second processing station 24. The first work spindle 5 is pivoted during machining of the workpiece 2 - if the type of processing requires it - by means of the spindle carrier 4c about the pivot axis 6 and thus the workpiece 2 is positioned relative to the tool 37 during processing. The associated pivoting of the second work spindle 55 and the corresponding workpiece 2 is compensated by the first processing station 23 in the manner described. With regard to the further operation, reference is made to the description of the preceding embodiments.

Hereinafter, a fifth embodiment of the invention will be described with reference to FIG. Structurally identical parts receive the same reference numerals as in the previous embodiments, the description of which reference is hereby made. Structurally different, but functionally similar parts receive the same reference numerals with a d followed. In addition to the first embodiment, the machine tool 1 d has a tailstock 56, which is arranged between the first processing station 23 and the second processing station 24 below the latter on the second side wall 17 of the base frame 3 in the z-direction. The tailstock 56 has a centering tip 57, which is rotatably mounted in the tailstock 56 about a tailstock rotation axis 58 extending in the z-direction. For machining of long and slender workpieces 2, for example of wave-shaped workpieces 2, these are aligned by pivoting the spindle carrier 4 about the pivot axis 6 in such a way positioned to the tailstock 56 that the spindle axis 7 coincides with the tailstock rotation axis 58. Subsequently, the workpiece 2 is arranged by lowering the work spindle 5 in the z-Richrung on the centering tip 57. During machining of the workpiece 2 this is stabilized by the tailstock 56. With regard to the further operation, reference is made to the description of the preceding embodiments.

The method for twist-free turning of a workpiece 2 is fundamentally independent of the configuration of the machine tool 1.

Decisive for the twist-free rotation is the position of the sheath 54 relative to the workpiece 2 to be machined, as shown in Figures 6 and 7, and the relative movement between the cutting edge 54 and the workpiece to be machined 2. The relative movement, for example, by a rotational movement can be generated as a result of pivoting of the spindle carrier 4, as described in the third embodiment. Alternatively, the relative movement can also be generated by a linear movement, for example in the x-direction, of the workpiece 2 and / or the cutting edge 54. Furthermore, the relative movement can be generated by a rotational movement of the cutting edge 54. Preferably, the cutting edge 54 can be fed relative to the workpiece 2, so that the chip thickness can be adjusted and / or the cutting edge 54 adjusted for a subsequent turning operation. As a result, in particular different rotational diameters of the workpiece 2 can be generated.

Claims

claims

1. Machine tool for multi-station machining of workpieces with - a base frame (3),

- A spindle carrier (4, 4c), which

a pivot axis running in a vertical z-direction

(6) and

- Is arranged on the base frame (3) pivotable about the pivot axis (6),

- At least one work spindle (5, 5, 55) for receiving workpieces to be machined (2), which

~ can be driven in rotation about a spindle axis (7) running in the z-direction, - can be moved linearly in the z-direction and is arranged suspended on the spindle carrier (4, 4c), and

~ together with the spindle carrier (4; 4c) about the pivot axis (6) is pivotable such that the spindle axis (7) along a circular arc (8) is movable, and - several along the circular arc (8) on the base frame (3) arranged processing stations (23, 24, 25, 23 a, 24, 25, 23 b, 24, 25) for processing the workpieces (2), and

- a control unit (45) for controlling the machining, characterized in that - the at least one work spindle (5; 5, 55) exclusively in the z-

Direction is linearly movable, so that the spindle axis (7) only along the circular arc (8) is movable,

at least one of the processing stations (24, 25, 23a, 24, 25) is arranged so as not to be linearly displaceable on the base frame (3), - The control unit (45) is designed such that during machining of the workpieces (2) at this at least one processing station (24, 25; 23a, 24, 25), the spindle axis (7) in a horizontal x and y Direction exclusively along the circular arc (8) by pivoting the spindle carrier (4, 4c) is positionable, and

- At most two work spindles (5; 5, 55) on the spindle carrier (4; 4c) are arranged.

2. Machine tool according to claim 1, characterized in that along the circular arc (8) a supply station (20) for feeding the workpieces to be processed (2) and a discharge station (21; 21a; 21b; 21c) for discharging the machined workpieces (2) is arranged.

3. Machine tool according to claim 1 or 2, characterized in that the base frame (3) is designed in the form of a polygon.

4. Machine tool according to one of claims 1 to 3, character- ized in that the supply station (20) and the discharge station

(21a, 21b, 21c) are arranged adjacent to each other on a common side of the base frame (3).

5. Machine tool according to one of claims 1 to 3, character- ized in that the supply station (20) and the discharge station

(21) are arranged on different sides of the base frame (3).

6. Machine tool according to one of claims 1 to 5, characterized in that two stations (20, 21, 23, 24, 25; 20, 21 a, 23 a, 24, 25; 20, 21b, 23b, 24, 25; 20, 21c, 23, 24, 25) on a common side of the base frame (3) are arranged, in particular a linearly non-movable first processing station (24, 25, 23a, 24, 25) and a second processing station (23 ; 23b) which is movable in at least one horizontal direction.

7. Machine tool according to one of claims 1 to 6, characterized in that for pivoting the spindle carrier (4) a gearless direct drive (13a) is provided.

8. Machine tool according to one of claims 1 to 7, characterized in that on the spindle carrier (4) exactly one working spindles (5) is arranged.

9. Machine tool according to one of claims 1 to 7, characterized in that on the spindle carrier (4c) exactly two in the z-direction independently movable work spindles (5, 55) are arranged.

10. Machine tool according to claim 9, characterized in that the two work spindles (5, 55) include a first offset angle (cpi), the second offset angle (φ ₂ ) between two stations (20, 21 c, 23, 24 ) corresponds.

11. Machine tool according to one of claims 1 to 10, characterized in that all processing stations (23a, 24, 25) are arranged linearly non-movably on the base frame (3).

12. Machine tool according to one of claims 1 to 10, characterized in that one of the processing stations (23) as a tool turret (27) with a horizontally extending turret axis of rotation (34) is arranged on a cross slide (26) and in a horizontal x-direction and in the z-direction is linearly movable.

13. Machine tool according to one of claims 1 to 12, characterized in that one of the processing stations (25; 23a, 25) as a counter spindle (42; 42, 46) extending in the z-direction

Counter spindle axis (44; 44, 47) is formed, which is arranged standing on the base frame (3).

14. Machine tool according to one of claims 1 to 13, character- ized in that one of the processing stations (23b) is designed as a tool holder (50) which is horizontally movable horizontally in the direction of the at least one work spindle (5).

15. Method for multi-station machining of workpieces, comprising the steps:

Providing a machine tool (1, 1a, 1b, 1c) according to one of claims 1 to 14,

- receiving a workpiece to be machined (2) by means of the at least one work spindle (5, 5, 55), - pivoting the spindle carrier (4, 4c) about the pivot axis (6) to a first, linearly non-movable processing station (24, 25, 23a, 24, 25),

- Processing the workpiece (2) by means of the first processing station (24, 25, 23 a, 24, 25), wherein the workpiece (2) during the Machining exclusively by pivoting the spindle carrier (4, 4c) along the circular arc (8) is positioned in a horizontal x and y direction, and

Pivoting the spindle carrier (4; 4c) about the pivot axis (6) to a second processing station (23, 24, 25; 23a, 24, 25;

24, 25).