Machine tool having a swivelling bridge with a deflection compensation device, and method for operating the machine tool

Abstract

The invention relates to a machine tool (1) comprising: - a base frame (2); - a work spindle (4) for receiving a tool (5); - a swivelling bridge (7) for receiving a workpiece (8, 9), wherein the swivelling bridge (7) is configured such that it can swivel about a swivel axis (10), wherein the swivelling bridge (7) is received such that it can swivel on a first swivel bearing (11) and a second swivel bearing (12), wherein a workpiece holder (13, 14) for directly or indirectly receiving the workpiece (8, 9) is provided on the swivelling bridge (7), wherein the workpiece holder (13, 14) is arranged between the first swivel bearing (11) and the second swivel bearing (12); - a digital computer (27) for controlling the movements of the machining tool (1). A deflection compensation device (28) for compensating for tilting of the workpiece (8, 9) due to deflection of the swivelling bridge (7) is provided on the swivelling bridge (7).

Description

[0001] Machine tool with a pivoting bridge having a deflection compensation device, and method for operating the machine tool

[0002] The invention relates to a machine tool. Furthermore, the invention relates to a method for operating a machine tool.

[0003] WO2018209373A1 discloses a machine tool comprising the following components: a machine frame; a spindle adjustment device arranged on the machine frame; at least one first work spindle mounted for rotation about a first spindle axis; a workpiece clamping device arranged on the machine frame and designed to accommodate at least a first workpiece and a second workpiece. The spindle adjustment device comprises a work head on which the work spindle is arranged. The workpiece clamping device comprises at least one first workpiece table, wherein the first workpiece table is mounted for pivoting about a first pivot axis.

[0004] The machine tool known from WO2018209373A1 has the disadvantage that workpieces produced with it may be inaccurate.

[0005] The inaccuracy can arise from the swivel bridge being elastically deformed due to the weight of the swivel bridge or the weight of the workpiece. This deflection of the swivel bridge causes the workpieces held on the swivel bridge to tilt. For example, if rotary tables are mounted on the swivel bridge to hold workpieces, the deflection of the swivel bridge causes the rotary tables to tilt.

[0006] The object of the present invention was to overcome the disadvantages of the prior art and to provide a device and a method by means of which a workpiece can be manufactured with increased precision.

[0007] This object is achieved by a device and a method according to the claims.

[0008] According to the invention, a machine tool is designed. The machine tool comprises:

[0009] - a base frame;

[0010] - a work spindle for holding a tool;

[0011] - a pivoting bridge for receiving a workpiece, wherein the pivoting bridge is designed to be pivotable about a pivot axis, wherein the pivoting bridge is pivotally received on a first pivot bearing and a second pivot bearing, wherein a workpiece holder is designed on the pivoting bridge for directly or indirectly receiving the workpiece, wherein the workpiece holder is arranged between the first pivot bearing and the second pivot bearing;

[0012] - a digital computer to control the movements of the machine tool.

[0013] A deflection compensation device is provided on the swivel bridge to compensate for any tilting of the workpiece caused by deflection of the swivel bridge.

[0014] The machine tool according to the invention offers the advantage that the deflection compensation device allows workpieces to be manufactured with increased precision. This can be achieved, in particular, by counteracting the gravity-induced deflection of the swivel bridge using the deflection compensation device. In particular, tilting of the workpiece can be compensated for using the deflection compensation device.

[0015] Furthermore, it may be expedient if a first workpiece holder for holding a first workpiece and a second workpiece holder for holding a second workpiece are formed on the swivel bridge, wherein the first workpiece holder is arranged on a first side of the longitudinal center at a first distance from the longitudinal center of the swivel bridge and wherein the second workpiece holder is arranged on a second side of the longitudinal center at a second distance from the longitudinal center of the swivel bridge. Particularly in the case of two workpiece holders, which are each arranged at a distance from the longitudinal center of the swivel bridge, if the swivel bridge deflects, the workpiece holder tilts and thus the workpiece tilts. The use of a deflection compensation device has proven to be advantageous, particularly in this type of machine configuration.

[0016] Furthermore, it can be provided that the first distance and the second distance are the same. This has the advantage that the first workpiece holder and the second workpiece holder have the same tilt and thus the tilt can be compensated with an equally large force. Furthermore, it can be provided that the deflection compensation device is coupled to the first workpiece holder and to the second workpiece holder, wherein an opposing force can be applied to the first workpiece holder and the second workpiece holder by means of the deflection compensation device. This has the advantage that the force acting on the first workpiece holder and on the second workpiece holder can cause a deformation of the first workpiece holder and the second workpiece holder.Thus, the angular position of the first workpiece holder and the second workpiece holder can be compensated by applying opposing forces. In particular, the deflection compensation device can be supported on the first workpiece holder and the second workpiece holder, so that no additional components of the swivel bridge are subjected to a force, which could lead to undesirable further deformation of the swivel bridge.

[0017] Furthermore, it can be provided that a first lever arm is coupled to the first workpiece holder and that a second lever arm is coupled to the second workpiece holder, and that a force can be applied to the first lever arm and the second lever arm by means of the deflection compensation device, wherein a bending moment can be applied to the first workpiece holder and the second workpiece holder by the application of the force. In particular, such a design of a first lever arm and a second lever arm offers the advantage that a bending moment can be introduced into the workpiece holders, whereby the tilting of the workpiece holders can be compensated.

[0018] Another advantageous embodiment provides for the deflection compensation device to comprise a linear actuator, in particular a hydraulic cylinder, wherein the linear actuator is coupled to the first lever arm at a first coupling point and to the second lever arm at a second coupling point. A force can be easily applied to the lever arm, particularly by means of a linear actuator, thereby inducing a bending moment. In particular, the linear actuator can be designed in the form of a hydraulic cylinder. Such a hydraulic cylinder can apply a high force to the lever arms, thereby inducing a high bending moment into the workpiece holder in order to compensate for an angular misalignment of the workpiece.As an alternative to the linear actuator combined with a lever arm, a swivel actuator can also be designed to directly apply a bending moment to the workpiece holders. Such a swivel actuator can, for example, be a hydraulic swivel cylinder.

[0019] According to a further development, it is possible for the deflection compensation device to comprise a first linear actuator, in particular a first hydraulic cylinder, wherein the first linear actuator is coupled to the first lever arm at a first coupling point and to the pivoting bridge at a second coupling point, and for the deflection compensation device to comprise a second linear actuator, in particular a second hydraulic cylinder, wherein the second linear actuator is coupled to the second lever arm at a third coupling point and to the pivoting bridge at a fourth coupling point. With such a design, the bending moment can be introduced separately and independently of one another in the first workpiece holder and in the second workpiece holder. Thus, any angular errors in the first workpiece holder and the second workpiece holder can be compensated for independently of one another.

[0020] As an alternative to the use of a first linear actuator and a second linear actuator, it can be provided that a single linear actuator is designed with a central housing for connection to the pivoting bridge and with a first piston rod for connection to the first lever arm and a second piston rod for connection to the second lever arm.

[0021] As an alternative to the linear actuator in the form of a hydraulic cylinder, the linear actuator can be designed in the form of an electrically operated linear actuator, for example with a stepper motor.

[0022] When using a linear actuator in the form of a hydraulic cylinder, it can be provided that it is coupled to a proportional valve, which is used to adjust the hydraulic cylinder.

[0023] Furthermore, it may be expedient if the first lever arm is rigidly coupled to the first workpiece holder and the second lever arm is rigidly coupled to the second workpiece holder, wherein the first workpiece holder and the second workpiece holder are rigidly held in the pivoting bridge and the force acting on the first lever arm and the second lever arm initiates an elastic deformation of the workpiece holders and / or the pivoting bridge. In such a design, the elasticity or component rigidity of the pivoting bridge is used to compensate for the tilting through appropriate bending. This has the advantage that the workpiece holders do not have to be pivotably held in the pivoting bridge.

[0024] Furthermore, the workpiece holder can comprise a rotary table configured to rotate the workpiece about a rotational axis. The rotary table's rotational axis, when the swivel bridge is undeformed, is arranged at a right angle to the swivel axis of the swivel bridge. In particular, the rotary table's rotational axis can intersect the swivel axis. A machine tool configured in this way, in particular, offers a high degree of flexibility with regard to workpiece machining. Any tilting of the rotary table can be compensated for by means of the deflection compensation device.

[0025] Furthermore, it can be provided that the first workpiece holder comprises a first rotary table which is designed to rotate the first workpiece about a first axis of rotation, wherein the first axis of rotation of the first rotary table is arranged at a right angle to the pivot axis when the pivot bridge is undeformed, and that the second workpiece holder comprises a second rotary table which is designed to rotate the second workpiece about a second axis of rotation, wherein the second axis of rotation of the second rotary table is arranged at a right angle to the pivot axis when the pivot bridge is undeformed. A machine tool designed in this way in particular has a high degree of flexibility with regard to workpiece machining. Any tilting of the rotary table can be compensated for by means of the deflection compensation device.

[0026] According to a particular embodiment, it is possible to configure a sensor to detect the tilt of the workpiece or the workpiece holder. The sensor is coupled to the digital computer, and the deflection compensation device is controllable based on the sensor's detection value. This offers the advantage that the actual tilt of the workpiece can be compensated for in a control loop, whereby any environmental influences such as temperature, weight of the workpiece, changes in the elastic modulus of the swivel bridge due to aging, and the like do not have to be considered in a calculation, but can be taken into account in the direct measurement.

[0027] According to an advantageous development, a mechanical guide rail can be provided, whereby the deflection compensation device is adjusted based on the pivoting position of the pivoting bridge. With such a design, it is not necessary to have a separate actuator or a separate power supply for deflection compensation. Rather, deflection compensation can be achieved through a positive guide.

[0028] Method for operating a machine tool comprising the method steps:

[0029] - Holding a tool in a work spindle;

[0030] - Holding a workpiece on a swivel bridge, wherein during operation of the machine tool the swivel bridge is swiveled about a swivel axis, wherein the swivel bridge is pivotally held on a first swivel bearing and a second swivel bearing, wherein a workpiece holder is formed on the swivel bridge for directly or indirectly holding the workpiece, wherein the workpiece holder is arranged between the first swivel bearing and the second swivel bearing;

[0031] - Controlling the movements of the machine tool using a digital computer.

[0032] A deflection compensation device arranged on the swivel bridge compensates for any tilting of the workpiece, whereby the tilting of the workpiece is caused by a deflection of the swivel bridge due to the weight of the swivel bridge and the parts located on it.

[0033] The method according to the invention offers the advantage that the deflection compensation device allows the workpieces to be manufactured with increased precision. This can be achieved, in particular, by counteracting the gravity-induced deflection of the pivot bridge using the deflection compensation device. In particular, tilting of the workpiece can be compensated for using the deflection compensation device.

[0034] Furthermore, it can be provided that the tilt of the workpiece is detected by a sensor, wherein the sensor is coupled to the digital computer, and the control of the deflection compensation device is based on the sensor's detection value. This offers the advantage that the actual tilt of the workpiece can be compensated for in a control loop, whereby any environmental influences such as temperature, weight of the workpiece, changes in the elastic modulus of the pivot bridge due to aging, and the like do not have to be considered in a calculation, but can be taken into account in the direct measurement.

[0035] Furthermore, it can be provided that the control of the deflection compensation device is based on the pivot position of the pivot bridge. This has the advantage that different deflections can be compensated for based on different pivot positions of the pivot bridge.

[0036] Another advantageous embodiment is one in which the control of the deflection compensation device can be based on the pivoting position of the pivoting bridge, wherein the tilting of the workpiece is detected by a sensor, wherein the control specifications of the digital computer are automatically adjusted based on the value detected in the sensor, in particular that the compensation adjustments are learned in the digital computer. This has the advantage that not only can a measured value of the angular misalignment be compensated, but that an expected angular misalignment can be compensated as soon as it occurs or before it occurs, so that no angular misalignment actually occurs during the machining of the workpiece, but rather it can be compensated in advance by appropriate knowledge of the expected values.In particular, it is conceivable that the computing unit of the machine tool can be trained accordingly through the use of artificial intelligence or neural networks in order to achieve exact compensation of the tilt.

[0037] According to a further development, it is possible to measure the weight of the workpiece, whereby the control of the deflection compensation device takes the weight of the workpiece into account. This has the advantage that different deflections can be taken into account for different workpieces.

[0038] In particular, it can be advantageous if the deflection of the swivel bridge for different workpiece weights is simulated in a computer-implemented simulation model, in particular in a finite element model, and stored in a deflection database, with the control of the deflection compensation device being based on the data from the deflection database. This has the advantage that the deflection compensation can be carried out based on an expected deflection of the swivel bridge. This allows the actual tilting of the workpiece or the workpiece holder to be compensated or balanced out during the different angular positions of the swivel bridge during workpiece machining. This makes it possible to cause no or as little tilting of the workpiece as possible during the entire machining of the workpiece, thereby improving the accuracy of the workpiece.

[0039] For a better understanding of the invention, it is explained in more detail using the following figures.

[0040] They show in a highly simplified, schematic representation:

[0041] Fig. 1 is a schematic representation of a first embodiment of a machine tool;

[0042] Fig. 2 is a schematic representation of a deflection of a swivel bridge of the machine tool;

[0043] Fig. 3 is a schematic representation of a first embodiment of the swing bridge with a deflection compensation device;

[0044] Fig. 4 is a schematic representation of a second embodiment of the swing bridge with the deflection compensation device;

[0045] Fig. 5 is a schematic representation of a third embodiment of the swing bridge with the deflection compensation device;

[0046] Fig. 6 is a schematic representation of a fourth embodiment of the swing bridge with the deflection compensation device.

[0047] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the position information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these position information must be applied analogously to the new position in the event of a change in position.

[0048] Fig. 1 shows a first embodiment of a machine tool 1. In particular, it can be provided that the machine tool 1 is used for machining workpieces.

[0049] The machine tool 1 can have a base frame 2. The base frame 2 can serve to hold various movable components of the machine tool 1. Furthermore, it can be provided that the machine tool 1 has a machining head 3. A work spindle 4 can be accommodated in the machining head 3. The work spindle 4 can serve to hold a tool 5. In particular, it can be provided that the tool 5 is rotated about a spindle axis 6 with the work spindle 4. Furthermore, it can be provided that the machine tool 1 has two or more work spindles 4. The work spindles 4 can each be arranged on a separate machining head 3 or on a common machining head 3.

[0050] As can also be seen from Fig. 1, it can be provided that the machine tool 1 comprises a pivoting bridge 7, which can serve to hold a first workpiece 8 or a second workpiece 9. The pivoting bridge 7 can be designed to be pivotable about a pivot axis 10 relative to the base frame 2. In particular, it can be provided that the pivoting bridge 7 is coupled to the base frame 2 by means of a first pivot bearing 11 and a second pivot bearing 12. The pivoting bridge 7 can extend between the first pivot bearing 11 and the second pivot bearing 12.

[0051] The fact that the swivel bridge 7 is mounted on the first swivel bearing 11 and the second swivel bearing 12 can lead to deflection of the central section of the swivel bridge 7. The deflection can be caused by the dead weight of the swivel bridge 7 or by the weight of the workpiece 8, 9 or by the weight of workpiece holders or clamping devices mounted on the swivel bridge 7. The deflection can vary in intensity depending on the component stiffness or the modulus of elasticity of the swivel bridge 7. A further factor for the extent of the deflection is the angular position of the swivel bridge 7 with regard to its rotation about the swivel axis 10. In particular, it is possible that a maximum deflection is reached when the swivel bridge 7 is in the position shown in Fig. 1.

[0052] When the swivel bridge is rotated 180°, meaning the workpieces are positioned at the bottom, a maximum deflection in the opposite direction can be achieved. When the swivel bridge 7 is rotated 90° compared to Fig. 1, the deflection of the swivel bridge 7 relevant for the tilting of the workpieces relative to each other can be zero or almost zero. However, when the swivel bridge 7 is positioned at 90°, lateral deflection of the swivel bridge 7 can occur.

[0053] As further evident from Fig. 1, a first workpiece holder 13 can be configured to receive the first workpiece 8. Furthermore, a second workpiece holder 14 can be configured to receive the second workpiece 9. The first workpiece holder 13 and the second workpiece holder 14 can serve for the direct or indirect reception of the first workpiece 8 and the second workpiece 9, respectively, on the pivoting bridge 7.

[0054] In the embodiment according to Fig. 1, the workpieces 8, 9 are indirectly attached to the swivel bridge

[0055] 7. In particular, a first rotary table 15 is provided for receiving the first workpiece 8. The first rotary table 15 can be used to rotate the first workpiece

[0056] 8 can be configured to rotate about a first axis of rotation 16. Analogously, a second rotary table 17 can be configured to receive the second workpiece 9. By means of the second rotary table 17, the second workpiece 9 can be mounted so as to be rotatable about a second axis of rotation 18 relative to the pivoting bridge 7.

[0057] As further evident from Fig. 1, it can be provided that the first workpiece holder 13 and the second workpiece holder 14 are arranged off-center on the pivot bridge 7 with respect to a longitudinal center 19 of the pivot bridge 7. It can be provided that the first workpiece holder 13 and the second workpiece holder 14 are arranged in a symmetrical arrangement off-center with respect to the longitudinal center 19 on the pivot bridge 7.

[0058] In particular, it can be provided that the first workpiece holder 13 is arranged on a first side 20 of the longitudinal center 19. Furthermore, it can be provided that the first workpiece holder 13 is arranged at a first distance 21 from the longitudinal center 19. Furthermore, it can be provided that the second workpiece holder 14 is arranged on a second side 22 of the longitudinal center 19. The second workpiece holder 14 can be arranged at a second distance 23 from the longitudinal center 19. With a symmetrical arrangement of the first workpiece holder 13 and the second workpiece holder 14, the first distance 21 and the second distance 23 can be the same.

[0059] As shown schematically in Fig. 1, a digital computer 27 can be designed which can serve to control the machine tool 1.

[0060] Fig. 2 shows a further and possibly independent embodiment of the swivel bridge 7, wherein the same reference numerals or component designations are used for the same parts as in the previous Fig. 1. To avoid unnecessary repetition, reference is made to the detailed description in the previous Fig. 1.

[0061] Fig. 2 shows a schematic representation of an embodiment of the swing bridge 7 or the deflection occurring on the swing bridge 7.

[0062] As can be seen from Fig. 2, the pivot bridge 7 can be provided with a bend. In the main position of the pivot bridge 7 shown in Fig. 2, the first workpiece holder 13 or the second workpiece holder 14 can be offset downwards relative to the pivot axis 10. Deflection of the pivot bridge 7 can occur in the direction of this bend. The pivot bridge 7 can be bent according to a bending line 24 shown in an overlaid manner.

[0063] Since, in the case of a corresponding deflection, as can be seen from Fig. 2, the bending line 24 has an angular position in the region of the first workpiece holder 13 and in the region of the second workpiece holder 14, the first workpiece holder 13 and the second workpiece holder 14 also have a corresponding angular misalignment.

[0064] In particular, it can be provided that when the pivoting bridge 7 is in a pivoted position, as shown in Fig. 2, the first rotary table 15 is tilted inwards by a first angle 25. Furthermore, the second rotary table 17 can be tilted inwards by a second angle 26. The first rotary table 15 and the second rotary table 17 can thus be tilted towards each other on their side facing away from the pivoting bridge 7. If the pivoting bridge 7 is pivoted by an angle of 180° with respect to the position as shown in Fig. 2, an opposite bend will occur and the two rotary tables 15, 17 will be tilted away from each other on their side facing away from the pivoting bridge 7.

[0065] Between the first pivoting position of the pivoting bridge 7, as shown in Fig. 2, and a second pivoting position rotated by 180°, the first angle 25 or the second angle 26 will continuously decrease and reach zero degrees of deviation at approximately 90° pivoting position of the pivoting bridge 7.

[0066] Fig. 3 shows a further embodiment of the swivel bridge 7, wherein again the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 and 2. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 and 2.

[0067] As can be seen from Fig. 3, a deflection compensation device 28 can be provided on the pivoting bridge 7, which can serve to specifically adjust the bending line 24 and thus compensate for the angular misalignment of the first rotary table 15 or the second rotary table 17. By means of the deflection compensation device 28, the first angle 25 and the second angle 26 can be influenced such that they are zero, regardless of the pivoting position of the pivoting bridge 7.

[0068] As can further be seen from Fig. 3, it can be provided that a first lever arm 29 is coupled to the first workpiece holder 13. Furthermore, it can be provided that a second lever arm 30 is coupled to the second workpiece holder 14. As can further be seen from Fig. 3, it can be provided that the deflection compensation device 28 comprises a first linear actuator 31, which is designed in the form of a hydraulic cylinder. The first linear actuator 31 can be coupled to the first lever arm 29 at a first coupling point 32. In particular, it can be provided that the first linear actuator 31 has an effective direction which is parallel to the pivot axis 10.

[0069] Furthermore, the first linear actuator 31 can be coupled to the second lever arm 30 at a second coupling point 33. Furthermore, it can be provided that the first linear actuator 31 is not fastened to the pivot bridge 7 between the first coupling point 32 and the second coupling point 33. Thus, the first lever arm 29 can act directly as a support for the second lever arm 30, and an equally large force can be applied to the first lever arm 29 or the second lever arm 30. The force applied to the first lever arm 29 or the second lever arm 30 can introduce a bending moment in the first workpiece holder 13 or in the second workpiece holder 14, which can serve to influence the bending line 24 and thus to compensate for the angular misalignment of the first angle 25 and the second angle 26.

[0070] As further shown in Fig. 3, a first sensor 34 can be provided, which can serve to detect the first angle 25. Furthermore, a second sensor 35 can be provided, which can serve to detect the second angle 26.

[0071] As further shown in Fig. 3, the first linear actuator 31 can be coupled to a first valve 39, which can serve to control the first linear actuator 31. The first valve 39 can be designed in the form of a proportional valve.

[0072] Fig. 4 shows a further embodiment of the swivel bridge 7, wherein again the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 to 3. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 to 3.

[0073] As can be seen from Fig. 4, it can be provided that the first linear actuator 31 is coupled to the first lever arm 29 at a first coupling point 32 and is coupled to the pivot bridge 7 at a second coupling point 33.

[0074] Furthermore, a second linear actuator 36 can be formed, which is coupled to the second lever arm 30 at a third coupling point 37 and to the pivot bridge 7 at a fourth coupling point 38. The first linear actuator 31 and the second linear actuator 36 can be controlled independently of one another, so that a different force effect can be achieved at the first lever arm 29 and the second lever arm 30.

[0075] Through these measures, the first angle 25 and the second angle 26 can be influenced independently of one another. As further evident from Fig. 4, the first linear actuator 31 can be coupled to a first valve 39, which can serve to control the first linear actuator 31. The first valve 39 can be designed in the form of a proportional valve.

[0076] As further shown in Fig. 4, the second linear actuator 36 can be coupled to a second valve 40. The second valve 40 can serve to control the second linear actuator 36. The second valve 40 can be designed in the form of a proportional valve.

[0077] In the embodiment according to Fig. 4, the first linear actuator 31 and the second linear actuator 36 can be designed as structurally independent units, which can be coupled to the pivot bridge 7 at the first coupling point 32 and the fourth coupling point 38, respectively. The first linear actuator 31 and the second linear actuator 36 can thus be immovably coupled to the pivot bridge 7 at the first coupling point 32 and the fourth coupling point 38, respectively, in the direction of action.

[0078] In an alternative embodiment, it is also conceivable that the first linear actuator 31 and the second linear actuator 36 have a common housing, which can be coupled to the swivel bridge 7 in a non-displaceable manner in the direction of action.

[0079] Fig. 5 shows a further embodiment of the swivel bridge 7, wherein again the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 to 4. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 to 4.

[0080] As can be seen from Fig. 5, it can be provided that the first linear actuator 31 is coupled to a slotted guide 41, wherein the force application of the linear actuator 31 varies depending on the pivoting angle position of the pivoting bridge 7. In particular, it can be provided that the first linear actuator 31 is coupled to an actuating actuator 42 by means of a line connection. The actuating actuator 42 can be pivoted along with the pivoting bridge 7 and rest against the slotted guide 41. Thus, depending on the pivoting angle position of the pivoting bridge 7, a different force application strength can be achieved on the first linear actuator 31. In an alternative embodiment to Fig. 5, not shown in detail, it can also be provided that the first lever arm 29 is mechanically coupled to the slotted guide 41 by means of a linkage.

[0081] A possible process sequence for operating a machine tool is described below. To machine the workpiece 8, 9, a tool 5 can be brought into machining engagement with the workpiece 8, 9, in particular for machining. In this case, the pivoting bridge 7 can be pivoted about the pivot axis 10 during machining.

[0082] At different pivoting positions of the pivoting bridge 7, a different deflection of the pivoting bridge 7 occurs, resulting in a different bending line 24 at different pivoting positions.

[0083] To compensate for this deflection or the resulting misalignment of the first rotary table 15 and the second rotary table 17, the deflection compensation device 28 can introduce a bending moment into the first workpiece holder 13 and the second workpiece holder 14. The bending moment can be selected such that the first angle 25 or the second angle 26 is 0° deviating from the ideal vertical position. In other words, the deflection compensation device 28 can ensure that the first axis of rotation 16 of the first rotary table 15 and the second axis of rotation 18 of the second rotary table 17 are parallel to one another or are each at a right angle to the pivot axis 10.

[0084] The magnitude of the force application and thus the torque application can be determined, for example, in a control process by detecting the current deviation of the first angle 25 and the second angle 26 using the first sensor 34 and optionally the second sensor 35. In an alternative embodiment, it is also possible to simulate the angular deviation of the first angle 25 and the second angle 26 under a wide variety of conditions using a finite element model and to transfer the simulation results accordingly to a compensation table, wherein the deflection compensation device 28 is controlled based on the compensation table.Furthermore, it is also conceivable that a neural network is provided to control the deflection compensation device 28, which is designed to control the correction of the angular deviation of the first angle 25 and the second angle 26 with such precision over time that the first rotary table 15 and the second rotary table 17 experience practically no angular deviation over time. The neural network can be trained by simulation, again based on a finite element model. Furthermore, it is also conceivable that the neural network is trained during ongoing operation of the machine tool 1 or a reference machine tool. To train the neural network, the first sensor 34 and / or the second sensor 35 can be installed on the machine tool 1 or the reference machine tool.

[0085] A reference machine tool can be an identical machine tool 1 that has multiple sensors and serves to monitor the deformations of the pivot bridge 7. Such a reference machine tool can be useful, for example, in series production, so that not every machine tool 1 needs to have comprehensive sensor technology.

[0086] Fig. 6 shows a further embodiment of the swivel bridge 7, wherein again the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 to 5. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 to 5.

[0087] As can be seen from Fig. 6, the first sensor 34 can be provided with a transmitter 43 and a receiver 44. The transmitter 43 can be arranged at a first longitudinal end of the pivoting bridge 7. The receiver 44 can be arranged at a second longitudinal end of the pivoting bridge. The transmitter 43 can emit electromagnetic radiation, for example light, to the receiver 44. The deflection of the pivoting bridge 7 and thus the angular tilt of the workpieces 8, 9 can be calculated from the height shift of the radiation at the receiver.

[0088] In a further, completely independent embodiment, it can be provided that the sensor 34 is designed as a length measuring system 45. Such a length measuring system 45 can be arranged on an outermost structural element of the pivot bridge 7. Furthermore, it can be provided that the length measuring system 45 is designed to measure an extension or a compression of the outermost structural element of the pivot bridge 7. This makes it possible to calculate the deflection of the pivot bridge 7 and thus the angular tilt of the workpieces 8, 9. In particular, it is conceivable that the length measuring system 45 is designed in the form of a light-dependent system. Furthermore, it is also conceivable that the length measuring system 45 is designed in the form of a strain gauge which detects the expansion of a component of the pivot bridge 7.

[0089] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0090] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0091] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0092] For the sake of clarity, it should be noted that, for a better understanding of the structure, some elements have been shown not to scale and / or enlarged and / or reduced in size.

[0093] Machine tool 29 First lever arm base frame 30 Second lever arm machining head 31 First linear actuator working spindle 32 First coupling point tool 33 Second coupling point spindle axis 34 First sensor swivel bridge 35 Second sensor first workpiece 36 Second linear actuator second workpiece 37 Third coupling point swivel axis 38 Fourth coupling point first swivel bearing 39 First valve second swivel bearing 40 Second valve first workpiece holder 41 Slide guide second workpiece holder 42 Actuator first rotary table 43 Transmitter first rotary axis 44 Receiver second rotary table 45 Length measuring system second rotary axis Longitudinal center first side of the longitudinal center first distance second side of the longitudinal center second distance

[0094] Bending line first angle second angle digital computer deflection compensation device

Claims

Patent claims 1. Machine tool (1) comprising: - a base frame (2); - a work spindle (4) for holding a tool (5); - a pivoting bridge (7) for receiving a workpiece (8, 9), wherein the pivoting bridge (7) is designed to be pivotable about a pivot axis (10), wherein the pivoting bridge (7) is pivotably received on a first pivot bearing (11) and a second pivot bearing (12), wherein a workpiece holder (13, 14) for directly or indirectly receiving the workpiece (8, 9) is designed on the pivoting bridge (7), wherein the workpiece holder (13, 14) is arranged between the first pivot bearing (11) and the second pivot bearing (12); - a digital computer (27) for controlling the movements of the machine tool (1); characterized in that a deflection compensation device (28) is formed on the pivoting bridge (7) to compensate for a tilting of the workpiece (8, 9) caused by a deflection of the pivoting bridge (7).

2. Machine tool (1) according to claim 1, characterized in that a first workpiece holder (13) for receiving a first workpiece (8) and a second workpiece holder (14) for receiving a second workpiece (9) are formed on the pivoting bridge (7), wherein the first workpiece holder (13) is arranged on a first side (20) of the longitudinal center (19) at a first distance (21) from the longitudinal center (19) of the pivoting bridge (7) and wherein the second workpiece holder (14) is arranged on a second side (22) of the longitudinal center (19) at a second distance (23) from the longitudinal center (19) of the pivoting bridge (7).

3. Machine tool (1) according to claim 2, characterized in that the deflection compensation device (28) is coupled to the first workpiece holder (13) and is coupled to the second workpiece holder (14), wherein by means of the deflection compensation device (28) an opposing force can be applied to the first workpiece holder (13) and the second workpiece holder (14).

4. Machine tool (1) according to claim 2 or 3, characterized in that a first lever arm (29) is coupled to the first workpiece holder (13) and that a second lever arm (30) is coupled to the second workpiece holder (14), and that by means of the deflection compensation device (28) a force can be applied to the first lever arm (29) and the second lever arm (30), wherein by the application of force a bending moment can be applied to the first workpiece holder (13) and the second workpiece holder (14).

5. Machine tool (1) according to claim 4, characterized in that the deflection compensation device (28) comprises a linear actuator (31, 36), in particular a hydraulic cylinder, wherein the linear actuator (31, 36) is coupled to the first lever arm (29) at a first coupling point (32) and is coupled to the second lever arm (30) at a second coupling point (33).

6. Machine tool (1) according to claim 4, characterized in that the deflection compensation device (28) comprises a first linear actuator (31), in particular a first hydraulic cylinder, wherein the first linear actuator (31) is coupled to the first lever arm (29) at a first coupling point (32) and is coupled to the pivoting bridge (7) at a second coupling point (33), and the deflection compensation device (28) comprises a second linear actuator (36), in particular a second hydraulic cylinder, wherein the second linear actuator (36) is coupled to the second lever arm (30) at a third coupling point (37) and is coupled to the pivoting bridge (7) at a fourth coupling point (38).

7. Machine tool (1) according to one of claims 4 to 6, characterized in that the first lever arm (29) is rigidly coupled to the first workpiece holder (13) and the second lever arm (30) is rigidly coupled to the second workpiece holder (14), wherein the first workpiece holder (13) and the second workpiece holder (14) are rigidly received in the pivoting bridge (7) and an elastic deformation of the workpiece holders (13, 14) and / or the pivoting bridge (7) is initiated by the force acting on the first lever arm (29) and the second lever arm (30).

8. Machine tool (1) according to one of the preceding claims, characterized in that the workpiece holder (13) comprises a rotary table (15) which is designed to rotate the workpiece (8, 9) about a rotation axis (16), wherein the rotation axis (16) of the rotary table (15) is arranged at a right angle to the pivot axis (10) when the pivot bridge (7) is undeformed.

9. Machine tool (1) according to one of claims 2 to 8, characterized in that the first workpiece holder (13) comprises a first rotary table (15) which is designed to rotate the first workpiece (8) about a first axis of rotation (16), wherein the first axis of rotation (16) of the first rotary table (15) is arranged at a right angle to the pivot axis (10) when the pivot bridge (7) is undeformed, and in that the second workpiece holder (14) comprises a second rotary table (17) which is designed to rotate the second workpiece (9) about a second axis of rotation (18), wherein the second axis of rotation (18) of the second rotary table (17) is arranged at a right angle to the pivot axis (10) when the pivot bridge (7) is undeformed.

10. Machine tool (1) according to one of the preceding claims, characterized in that a sensor (34, 35) is designed to detect the tilting of the workpiece (8, 9) or the workpiece holder (13, 14), wherein the sensor (34, 35) is coupled to the digital computer (27) and the deflection compensation device (28) is controllable on the basis of the detection value of the sensor (34, 35).

11. Machine tool (1) according to one of the preceding claims, characterized in that a mechanical link guide (41) is formed, wherein an adjustment of the deflection compensation device (28) takes place on the basis of the pivoting position of the pivoting bridge (7).

12. Method for operating a machine tool (1) comprising the method steps: - Holding a tool (5) in a work spindle (4); - Holding a workpiece (8, 9) on a swivel bridge (7), wherein during operation of the machine tool (1) the swivel bridge (7) is swivelled about a swivel axis (10), wherein the pivoting bridge (7) is pivotably received on a first pivot bearing (11) and a second pivot bearing (12), wherein a workpiece holder (13, 14) for directly or indirectly receiving the workpiece (8, 9) is formed on the pivoting bridge (7), wherein the workpiece holder (13, 14) is arranged between the first pivot bearing (11) and the second pivot bearing (12); - Controlling the movements of the machine tool (1) by means of a digital computer (27); characterized in that a tilting of the workpiece (8, 9) is compensated for by means of a deflection compensation device (28) arranged on the pivoting bridge (7), wherein the tilting of the workpiece (8, 9) is caused by a deflection of the pivoting bridge (7) due to the weight of the pivoting bridge (7) and the parts located thereon.

13. The method according to claim 12, characterized in that the tilting of the workpiece (8, 9) is detected by means of a sensor (34, 35), wherein the sensor (34, 35) is coupled to the digital computer (27) and the control of the deflection compensation device (28) is carried out on the basis of the detection value of the sensor (34, 35).

14. Method according to claim 12 or 13, characterized in that the control of the deflection compensation device (28) is carried out on the basis of the pivoting position of the pivoting bridge (7).

15. Method according to one of claims 12 to 14, characterized in that the control of the deflection compensation device (28) is carried out on the basis of the pivoting position of the pivoting bridge (7), the tilting of the workpiece (8, 9) being detected by means of a sensor (34, 35), the control specifications of the digital computer (27) being adapted automatically on the basis of the value detected in the sensor (34, 35), in particular that the compensation adjustments are taught in in the digital computer (27).

16. Method according to one of claims 12 to 15, characterized in that the weight of the workpiece is detected, wherein the control of the deflection compensation device (28) takes place taking into account the weight of the workpiece.

17. Method according to one of claims 12 to 15, characterized in that the deflection of the swivel bridge (7) is simulated at different workpiece weights in a computer-implemented simulation model, in particular in a finite element model, and is stored in a deflection database, wherein the control of the deflection compensation device (28) is carried out on the basis of the data from the deflection database.

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