MACHINE TOOL

Abstract

A machine tool for machining workpieces has a machine frame, at least one component part which can be moved along a movement path by means of a power-operated drive unit, at least one frame part, which is connected to the machine frame and which is arranged at an end position in the movement path of the component part, and at least a first stop, via which the component part in contact with the frame part when said component part is in the end position, wherein the first stop lies outside the movement path.

Claims

1. A machine, comprising a machine frame, a power-operated drive unit, at least one component part moved by said power-operated drive unit relative to said machine frame along a movement path, at least one frame part connected to said machine frame and arranged at an end position of movement of said component part in the movement path, and a first and at least a second stop, each stop situated between the component part and the frame part, at least when the component part is in the end position, wherein said first and at least second stops are designed and arranged in such a way that, when the component part is in the end position, said component part is in contact with the frame part only via a first of said two stops.

2. The machine of claim 1, embodied as a machine tool for machining workpieces.

3. A machine, comprising a machine frame, a power-operated drive unit, at least one component part moved by said power-operated drive unit relative to said machine frame along a movement path, at least one frame part connected to said machine frame and arranged at an end position of movement of said component part in the movement path, and at least a first stop, said first stop being situated between the component part and the frame part, at least when the component part is in the end position, wherein said first stop lies outside of the movement path.

4. The machine of claim 3, embodied as a machine tool for machining workpieces.

5. The machine of claim 3, wherein at least a second stop is provided, said first and at least second stops are designed and arranged in such a way that, when the component part is in the end position, said component part is in contact with the frame part only via a first of said two stops.

6. The machine of claim 3, wherein said first stop is arranged on the component part.

7. The machine of claim 3, wherein said first stop is arranged on the frame part.

8. The machine of claim 1, wherein at least one of said first and second stop is arranged on the component part.

9. The machine of claim 1, wherein at least one of said first and second stop is arranged on the frame part.

10. The machine of claim 1, wherein said first and said at least second stop are arranged on the component part.

11. The machine of claim 1, wherein said first and said at least second stop are arranged on the frame part.

12. The machine of claim 3, wherein a holder is provided, which holder is arranged such as to be moved into the movement path between the component part and the frame part, said first stop being arranged on said holder.

13. The machine of claim 1, wherein a holder is provided, which holder is arranged such as to be moved into the movement path between the component part and the frame part, at least one of said first and said at least second stops being arranged on said holder.

14. The machine of claim 3, wherein a first sensor is provided, said first sensor arranged for detecting whether said component part is in its end position.

15. The machine of claim 14, wherein said first sensor is associated with said first stop.

16. The machine of claim 1, wherein a first sensor is provided, said first sensor arranged for detecting whether said component part is in its end position.

17. The machine of claim 16, wherein said first sensor is associated with said first stop.

18. The machine of claim 16, wherein a second sensor is provided, said second sensor arranged for detecting a change in a spacing between the frame part and the component part when said component part is in its end position.

19. The machine of claim 18, wherein said second sensor is associated with said second stop.

20. The machine of claim 3, wherein a second sensor is provided, said second sensor arranged for detecting a change in a spacing between the frame part and the component part when said component part is in its end position.

21. The machine of claim 20, wherein at least a second stop is provided, said first and at least second stops are designed and arranged in such a way that, when the component part is in the end position, said component part is in contact with the frame part only via a first of said two stops, and wherein said second sensor is associated with said second stop.

22. The machine of claim 1, wherein said drive unit comprises a motor, which motor is coupled to the component part in such a way that, when said motor rotates, said component part is traversed along the movement path, and wherein a monitoring device is provided, which monitoring device detects at least one of said rotation of said motor and said movement of said component part.

23. The machine of claim 3, wherein said drive unit comprises a motor, which motor is coupled to the component part in such a way that, when said motor rotates, said component part is traversed along the movement path, and wherein a monitoring device is provided, which monitoring device detects at least one of said rotation of said motor and said movement of said component part.

24. The machine of claim 22, wherein said component part performs a rotary movement along a circular movement path due to the rotation of the motor.

25. The machine of claim 23, wherein said component part performs a rotary movement along a circular movement path due to the rotation of the motor.

26. The machine of claim 22, wherein said drive unit comprises a ball screw driven by said motor, on which ball screw a spindle nut is seated, which spindle nut is connected to said component part in such a way that said component part follows a linear movement path along the ball screw when the ball screw is rotated by means of the motor.

27. The machine of claim 23, wherein said drive unit comprises a ball screw driven by said motor, on which ball screw a spindle nut is seated, which spindle nut is connected to said component part in such a way that said component part follows a linear movement path along the ball screw when the ball screw is rotated by means of the motor.

28. The machine of claim 26, wherein said the monitoring device detects said rotation of said ball screw.

29. The machine of claim 27, wherein said the monitoring device detects said rotation of said ball screw.

30. The machine of claim 26, wherein an axis of rotation of said ball screw is aligned vertically and said component part is moved vertically upward or downward.

31. The machine of claim 27, wherein an axis of rotation of said ball screw is aligned vertically and said component part is moved vertically upward or downward.

32. The machine of claim 30, wherein said ball screw is arranged vertically below said motor.

33. The machine of claim 31, wherein said ball screw is arranged vertically below said motor.

34. The machine of claim 1, wherein said component part comprises a vertically aligned tool spindle having a spindle chuck for gripping a machining tool.

35. The machine of claim 3, wherein said component part comprises a vertically aligned tool spindle having a spindle chuck for gripping a machining tool.

36. A method for operating a machine, said machine comprising a machine frame, a power-operated drive unit, at least one component part moved by said power-operated drive unit relative to said machine frame along a movement path, at least one frame part connected to said machine frame and arranged at an end position of movement of said component part in the movement path, and at least a first stop, said first stop being situated between the component part and the frame part, at least when the component part is in the end position, said method comprising the steps of a) moving said component part into said end position by means of said drive unit, until said component part rests against said frame part via said first stop, b) exerting a further force on said component part by means of said drive unit, thereby pushing said component part while being in the end position towards the frame part, c) detecting whether a further movement of at least one of the component part and in the drive unit takes place, and d) outputting a fault message if a movement is detected in step c).

37. The method of claim 36, wherein said first stop lies outside of the movement path.

38. The method of claim 36, wherein said first stop lies centrally to the movement path.

39. The method of claim 36, wherein said machine is embodied as a machine tool for machining workpieces.

40. The method of claim 36, wherein at least a second stop is provided, said first and at least second stops are designed and arranged in such a way that, when the component part is in the end position, said component part is in contact with the frame part only via a first of said two stops.

41. The method of claim 36, wherein a holder is provided, said first stop being arranged on said holder, said holder being moved into the movement path between the component part and the frame part prior to step a).

42. The method of claim 36, wherein a first sensor is provided, said first sensor detecting in step a) whether said component part is in its end position.

43. The method of claim 36, wherein a second sensor is provided, said second sensor detecting in step c) a change in a spacing between the frame part and the component part.

44. The method of claim 36, wherein said drive unit comprises a motor, which motor is coupled to the component part in such a way that, when said motor rotates, said component part is traversed along the movement path, and wherein a monitoring device is provided, which monitoring device detects in step c) at least one of said rotation of said motor and said movement of said component part.

45. The method of claim 44, wherein said drive unit comprises a ball screw driven by said motor, on which ball screw a spindle nut is seated, which spindle nut is connected to said component part in such a way that said component part follows a linear movement path along the ball screw when the ball screw is rotated by means of the motor, wherein in step c) said the monitoring device detects said rotation of said ball screw.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Embodiments of the invention are shown in the drawing and are explained in greater detail in the following description. In the drawing:

[0081] FIG. 1 shows a simplified illustration in a schematic side view of a machine tool on which the novel method can be carried out;

[0082] FIG. 2 shows a schematic illustration of a drive unit for a component part of the machine tool from FIG. 1, said component part following a linear movement path, the machine tool having two stops seated on a frame part between the component part and the frame part;

[0083] FIG. 3 shows an illustration like that in FIG. 2, wherein only one stop is provided, this being seated on the component part;

[0084] FIG. 4 shows an illustration like that in FIG. 2, wherein both stops are seated on the frame part;

[0085] FIG. 5 shows an illustration like that in FIG. 2, wherein one stop is seated on the component part and one stop is seated on the frame part; and

[0086] FIG. 6 shows an illustration similar to that in FIG. 2, wherein the component part follows a circular movement path.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0087] FIG. 1 illustrates, in a schematic side view that is not to scale, a machine tool denoted overall by reference numeral 10.

[0088] The machine tool 10 has a traveling column 12, which is arranged by a first slide guide 14 on a cross piece 16. The traveling column 12 can be traversed on the cross piece 16 with the aid of the first slide guide 14 in the direction of an axis which is usually referred to as the y axis and is here illustrated symbolically by an arrow 18. It is self-evident that the traveling column 12 is traversed by motor on the first slide guide 14, although a corresponding drive unit is not illustrated here for reasons of clarity.

[0089] The cross piece 16 is supported on a machine frame 22 via a second slide guide 20. The second slide guide 20 allows movement of the cross piece 16 along a second axis, which is here indicated by reference numeral 24. Reference numeral 24 denotes the so-called X axis. It is self-evident that the movement of the cross piece 16 on the second slide guide 20 is also accomplished with the aid of a suitable drive unit, which is not illustrated here for reasons of clarity.

[0090] A spindle head 25 having a tool spindle 26 mounted rotatably therein is mounted in a vertically suspended manner on the traveling column 12. At its lower end, the tool spindle 26 has a spindle chuck 28, into which a tool holder 29 having a machining tool 30 secured thereon can be clamped in a known manner. Typically, the tool holder is standardized and is of the steep taper (SK) or hollow shank taper (HSK) type. The tool spindle 26 is designed to rotate the machining tool 30 about its spindle axis 32, this being indicated by an arrow 34. Typically, the tool spindle 26 is capable of rotating the machining tool 30 at several thousand revolutions per minute in order, in particular, to allow drilling and milling of metal workpieces.

[0091] The tool spindle 26 can be traversed on the traveling column 12 in the direction of an arrow 36, in this case therefore in a vertical direction, by means of a drive unit (likewise not shown), which can be designed as a ball screw or linear direct drive. Accordingly, the tool spindle 26 is mounted on the traveling column 12 by means of a third slide guide 38. The movement of the tool spindle 26 in the direction of the arrow 36 is generally referred to as the Z axis. Typically, the three slide guides 14, 20 and 38 for the three motion axes 18, 24, 36 are orthogonal to one another.

[0092] The machine tool 10 is therefore a traveling column machine with a vertical tool spindle 26, on which all three motion axes 18, 24, 36 are implemented in the machining tool 30.

[0093] Reference 40 denotes a workpiece table, which is mounted on the machine frame and on which a workpiece 42 to be machined is clamped. Reference 44 denotes a housing, which encloses the components of the machine tool 10 which have been described thus far. Finally, reference 46 denotes a machine controller, with the aid of which all the movements of the machine tool 10 and auxiliary units (coolant supply, compressed air and the tool magazine described below) are controlled.

[0094] In this way, the machining tool 30 can be traversed in a workspace denoted by 48 in order to machine the workpiece 42 there.

[0095] During this machining, different machining tools 30 are employed, and these are held ready in a tool magazine 50 illustrated only very schematically in FIG. 1.

[0096] To change tools, the traveling column moves toward the rear in the y direction 18, that is to say to the right in FIG. 1. The tool spindle 26 is now above the tool magazine 50, in which an empty space is provided into which the tool spindle 26 then places the tool holder 29 with the machining tool 30 that has been used up to this point. The tool magazine 50 then traverses an occupied magazine space into the transfer position below the tool spindle 26, in which a tool holder 29 with a machining tool 30 now envisaged for use is situated. This type of tool change is referred to as a pickup process.

[0097] FIG. 2 shows a drive unit 62 for a component part 63 of the machine tool 10 from FIG. 1.

[0098] The component part 63 can be the spindle head 25, for example, and therefore the drive unit 62 is aligned vertically. However, it is also possible to use the drive unit 62 for the cross piece 16 or the traveling column 12, and then the drive unit 62 is aligned horizontally.

[0099] The drive unit 62 comprises a motor 64, which, in the example shown, is a stepping motor electrically supplied with and driven by control signals from the machine controller 46.

[0100] The motor 64 has a motor hub 65, which is connected by a torsionally rigid coupling 66 to a ball screw 67, which is situated vertically below the motor 64 and on which a spindle nut 68 is arranged.

[0101] The spindle nut 68 is connected to the component part 63 by means of a connecting part 69.

[0102] The ball screw 67 and the motor hub 65 are aligned coaxially with one another and have a vertically aligned axis of rotation 70, enabling the motor 64 to rotate the ball screw 67 clockwise and counterclockwise as per arrow 71 via the coupling 66.

[0103] During this rotation of the ball screw 67, the spindle nut 68 and thus the component part 63 are traversed along a linear movement path 72 in an upward direction, i.e. toward the motor 64 and hence counter to gravity, or in a downward direction and hence away from the motor 64 and thus in the direction of gravity.

[0104] Since the coupling 66 is torsionally rigid, the ball screw 67 follows the revolutions of the motor hub 65 without play. This gives rise to a movement of the spindle nut 68 determined by the pitch of the ball screw 67. The movements of the spindle nut 68 along the ball screw 67 are monitored with the aid of a sensor 73, which is here designed as an indicated glass scale. The sensor 73 is connected by a line 74 to a monitoring device 75, which can be part of the machine controller 46.

[0105] A sensor 76 detects the rotation of the motor hub 65 and hence the rotation of the motor 64. The sensor 76 is connected by a line 77 to the monitoring device 75.

[0106] A further sensor 78 detects the rotation of the ball screw 67. The sensor 78 is connected by a line 79 to the monitoring device 75.

[0107] From the signals of the sensors 73, 76, 78, the monitoring device 75 determines whether the rotation of the motor 64, the ball screw 67 and the component part 63 coincide, i.e. that the actual movement of the component part 63 along the movement path 72 coincides with the movement determined by the rotation of the motor 64 via the pitch of the ball screw 67.

[0108] If this is not the case, the coupling 66 or the ball screw 67 may be broken, for example. The monitoring device 75 then outputs a fault message 80.

[0109] Provided at the lower end 82 of the ball screw 67 is a frame part 83, which is connected to the machine frame 22 and on which a first stop 84 and a second stop 85 are arranged. The frame part 83 can be connected firmly to the machine frame 22 or arranged on a holder 86, which can be pivoted into the movement path 72 when required.

[0110] In this way, an end position for the movement of the component part 63 along the movement path 72 is defined, as illustrated schematically by means of FIG. 3, in which the component part 63 is in its end position.

[0111] The machine tool is just one example of a machine in which the invention can be employed. For example, the machine can be designed as a machine tool having a horizontal tool spindle or without a tool magazine or can be a handling machine, drilling machine, press or the like.

[0112] The only important point is that the machine 10 has a machine frame 22, a component part 63 which can be moved along a movement path 72 by means of a power-operated drive unit 62, a frame part 83, which is connected to the machine frame 22 and which is arranged at an end position in the movement path 72 of the component part 63, and a first stop 84, via which the component part 63 is in contact with the frame part 83 when said component part is in the end position and which, in one embodiment, lies outside the movement path 72, as shown in principle in FIG. 2.

[0113] FIG. 3 shows the component part 63 from FIG. 2 in its end position 87, in which the first stop 84, which is here arranged on the component part 63, rests against the frame part 83, with the result that the component part 63 is at a distance from the frame part 83 which corresponds to the length L1 of the first stop 84 in the direction of the movement path 72.

[0114] Here, as a departure from the illustrative embodiment in FIG. 2, the first stop 84 is not only arranged on the component part 63 but is also arranged there coaxially with the movement path 72. Here, the lower end 82 of the ball screw 67 is mounted in the frame part 83 connected to the machine frame 22.

[0115] In FIG. 3, the movement path 72 of the component part is shown as being coaxially in the ball screw 67, i.e. central with respect to the point of application at which the force that moves the component part along the movement path 72 is exerted on said part. Since the first stop 84 is situated centrally with respect to the movement path 72, the component part 63 cannot move further, i.e. cannot move around the stop 84 or bend, be deformed or twist past it, if it continued to be pressed onto the stop 84 by the drive unit 62.

[0116] If the motor 64 continues to be energized in the situation shown in FIG. 3, however, the motor hub 65, the coupling 66 and the ball screw 67 must withstand the force exerted on the component part 63 by the motor 64 via these machine parts since the component part cannot continue to move downward in FIG. 3. If one of these machine parts were to break, twist, be deformed or bend, this unwanted movement in the drive unit 62 would be detected by the sensors 73, 76, 78 shown in FIG. 2 and would be recognized as faults in the monitoring device 75, and a fault message 80 would be output.

[0117] When the component part 63 is in the end position 87, further exertion of force by the motor 64 thus allows a simple test as to whether machine parts of the drive unit 62 have lost their strength and/or stiffness to such an extent due to wear, material fatigue, material defects or the like that there is the possibility of accuracy problems in the operation of the machine and/or the occurrence of safety problems.

[0118] When the stop 84 is situated outside the movement path 72, as is the case in FIG. 4, an unwanted movement of the component part 63 can additionally be caused and detected if the motor 64 continues to be energized. In FIG. 4, both stops 84, 85 are arranged on the frame part 83.

[0119] Because the stop 84 does not lie in the direction of the exertion of force, the component part 63 can bend, be deformed or twist around the stop 84 or past said stop if it is soft or flexible in relation to the force exerted by the drive unit 62.

[0120] This unwanted movement of the component part 63, which is indicated in FIG. 4 by a dashed arrow 88, can likewise be detected by the sensors 73, 76, 78 and can be detected in the monitoring device 75 as a fault, whereupon a fault message 80 is output.

[0121] As a safety precaution, the second stop 85 is provided, which is at a distance 89 from the component part 63 in the direction of the movement path 72 when the first stop 84 is already resting against the component part 63, with the result that the component part 63 can still bend by the distance 89 in the event of an unwanted movement before it is blocked by the second stop 85.

[0122] The first stop 84 once again has the length L1 in the direction of the movement path 72, while the second stop 85 has the length L2 in the direction of the movement path, said length L2 being less than length L1 by the distance 89.

[0123] In the embodiment in FIG. 4, the second stop 85 is likewise situated outside the movement path 72 but could also be arranged centrally.

[0124] In order to further improve the detection of an unwanted movement or to provide an alternative possibility of detection, a sensor 91 which detects whether the component part 63 has reached its end position 87, i.e. is resting against the frame part 83 via the stop 84, is arranged on the first stop 84 according to the embodiment in FIG. 5. The sensor 91 can be a simple limit switch. It is connected to the monitoring device 75 by a line which is not illustrated.

[0125] Arranged on the second stop 85 is a sensor 92, which detects the distance 89 between the component part 63 and the stop 85 and the reduction in said distance in the event of an unwanted movement of the component part 63. The sensor 92 can be a simple distance sensor. It is connected to the monitoring device 75 by a line which is not illustrated.

[0126] In the embodiment in FIG. 5, the first stop 84 is arranged on the component part 63, and the second stop 85 is arranged on the frame part 83.

[0127] From the signals of the sensors 91, 92, the monitoring unit 75 detects when a component part 63 situated in an end position 87 continues to move, is deformed, bent or twisted etc. in an unwanted way and outputs the fault message 80.

[0128] Whereas both stops 84, 85 are arranged on the frame part 83 in the embodiment in FIG. 4, it is also possible for both to be provided on the component part 63.

[0129] In addition to the unwanted movement of the component part, the sensors 73, 76, 78 which are shown in FIG. 2 can also be used in the embodiments in FIGS. 4 and 5 to detect an unwanted movement in the drive unit 62, as has already been described above in connection with FIG. 3.

[0130] Whereas the component part 13 in the embodiments in FIGS. 2 to 5 follows a linear movement path 72, it moves on a circular movement path 94 in the embodiment in FIG. 6.

[0131] The component part 63 is connected to a rotary drive 95, which moves it backward and forward along the movement path 94, around an axis of rotation 96, between two frame parts 83, 83, which define the end positions 87, 87.

[0132] First and second stops 84, 85 and 84, 85, which face the component part 63, are arranged on the frame parts 83, 83. Once again, the first stop 84, 84 has the length L1, and the second stop 85 has the length L2, with the result that the component part 13 rests against the frame part 83, 83 via the stop 84, 84 when it is in its end position 87, 87.

[0133] Once again, the sensor 91, 91 is arranged on the first stop 84, 84, and the sensor 92, 92 is arranged on the second stop 85, 85.

[0134] If, in order to test whether an accuracy or safety problem exists or could occur, the rotary drive 95 is activated in such a way that it continues to press the component part 63 against the frame part 83, 83 when said part is in the end position 87, 87, an unwanted movement of the component part 63 can be detected from the signals of the sensor 92, as in the embodiment in FIG. 5.