DE9015333U1 - Device for changing tools on machine tools - Google Patents

Description

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This file number: 5681/90

Bergmann & Steffen GmbH 4905 Spenge

Device for changing tools on machine tools

The invention relates to a device for changing at least two machining tools to be used in work spindles by means of an associated changing device with drive shaft and pinions.

It is known to equip such devices for changing using a changing device in such a way that one or the other machining tool is alternately brought from a tool magazine into the work spindle of the machine tool in order to be able to machine workpieces afterwards. During the changing process the work spindle rests unproductively.

For this purpose, it is known to arrange a double gripper on the changing device, which alternately exchanges processing tools. A new tool is taken from a magazine chain, while the tool taken from the machine tool is inserted into the same magazine chain.

The object of the invention is to create a device for changing the aforementioned type, in which a processing tool is exchanged for a new processing tool even if a previously engaged processing tool is simultaneously processing workpieces.

This object is achieved in a device for changing according to the aforementioned type in that a block which carries out a back and forth pivoting movement has several work spindles arranged at a distance from one another, each of which has a tool holder, and the work spindles are each coupled to several alternately drivable pinion groups, each of which is assigned an output shaft which is coupled to a servomotor and can be switched on and off by means of intermediate couplings, and each pinion group is assigned a main coupling.

Such a block equipped with a holder with several working spindles is designed as a separate device in such a way that it can be detachably inserted into a machine tool.

In a preferred embodiment, two work spindles can be arranged at a distance from one another and - viewed in the longitudinal direction of the machine tool - in alignment with one another in the block forming a spindle holder.

For this purpose, the block can carry a gear, a worm wheel or the like on a collar on the top, which is coupled to a drivable rack, a worm or the like.

With such a device for changing two or more processing tools, there is the advantageous possibility of exchanging a new tool in quick succession with a tool that is currently in use by simply swiveling it.

During the swivel movement, the previously rotating tool spindle can be braked by a main drive motor that rotates the drive shaft, an associated servo motor then takes over the positioning of the spindle for changing

Process. The other one equipped with a new tool
The spindle is immediately accelerated again.

This results in a rapid change of tools, for example from a magazine with more than one hundred
The change can be carried out in a controlled and gentle manner, as it takes place during the main working hours of the
This means that very short chip-to-chip times can be achieved on a machine tool equipped with such a device.

The tool can also be checked for breakage while the machine is still producing, using a scanning device with a movement distance comparison. This significantly reduces the machine's idle times and the machine achieves very high productivity.

Further features emerge from the subclaims.

The protection extends not only to the individual features, but also to their combination.

An embodiment of the invention is shown in the drawing and is described in more detail below. Show:

Fig. 1 is a perspective view of a machine tool with a changing device for machining tools to be accommodated;

Fig. 2 is a view of the same machine according to line II in Fig. 1;

Fig. 3 is an enlarged view of the changeover device with gearbox compared to Fig. 2;

Fig. 4 shows a detail of Fig. 3 with a schematic representation of a sensing device for a tool breakage.

A known machine tool for machining, for example, small parts of various types has a machine frame (10), on the machine roof (11) of which a new changing device (12) for holding machining tools such as drills (13), milling cutters (14) or the like is arranged.

The machine roof (11) has a recess (15) for a roller bearing (16), whereby an imaginary central axis of the roller bearing (16) inserted into the recess (15) of the machine roof (11) runs perpendicular to the installation floor of the machine tool. The recess (15) for receiving the roller bearing (16) is followed by a coaxial bore (17) penetrating the thickness of the machine roof (11).

The structure of the changing device (12) is described as follows:

The changing device (12) has a spindle holder (18) which accommodates two working spindles (19', 19") in a bearing-like manner and which is supported on the roller bearing (16) with its ring-shaped collar (20) designed as a worm wheel, while the end of the spindle holder (18) pointing towards the installation floor of the machine tool - viewed in terms of height in the axial direction - penetrates the bore (17) and projects into the working area of the machine tool.

The two work spindles (19, 19") are arranged in the spindle holder (18) at a distance from one another - viewed in the longitudinal direction of the machine tool - and are aligned with one another. Each of the two work spindles (19, 19") has a tool holder (21 a) or (21 b) coaxially connected to it and extending into the working area of the machine tool. The end of the respective work spindles (19', 19") opposite this tool holder (21 a) or (21 b) projects into a recess (22) surrounded by the annular collar (20) of the spindle holder (18). A first pinion (19 a) and a second pinion (19 b) are each placed onto this end of the two work spindles (19*, 19") projecting into the recess (22), the first pinion (19 a) engaging with a third pinion (23 a) arranged towards the center axis of the spindle holder (18). This third pinion (23 a) is coaxial with a coupling half (24) - e.g. B. in one piece - connected, whereby both - third pinion (23 a) and coupling half (24) - are arranged rotatably on a drive shaft (23) of a servomotor (25) by means of roller bearings (26). A second coupling half (27) is coaxial with the output shaft (23), fixedly arranged on it, e.g. by means of a feather key (28) between the coupling shaft (24) and the servomotor (25).

The third pinion (23 a) is in engagement with a fourth pinion (31) arranged rotatably on a main drive shaft (29) by means of a roller bearing (30), the fourth pinion (31) being connected, for example, in one piece, to a coupling half (33) arranged coaxially to the spindle holder (18) on the main drive shaft (29) and rotatably by means of a roller bearing (32). Between the coupling half (33) and the spindle holder (18), a second coupling half (34) is arranged, also coaxially with the main drive shaft (29), and is fixedly arranged on the main drive shaft (29) by means of a key (35), for example. The end of the main drive shaft (29) towards the spindle holder (18) is rotatably mounted in the spindle holder by means of a roller bearing (36).

Above the fourth pinion (31), a fifth pinion (37) is mounted coaxially on the main drive shaft (29) by means of a roller bearing (38). This fifth pinion (37) is also connected, for example, in one piece, to a coupling half (42) facing a roof (39) of a cross member (40) and arranged coaxially on the main drive shaft (29) by means of a roller bearing (41). Between the coupling half (42) and the roof (39) of the cross member (40), a second coupling half (43) is arranged firmly on the main drive shaft (29), for example by means of a feather key (44).

The main drive shaft (29), which runs coaxially with the spindle holder (18) and is rotatably mounted in it, has a sixth pinion (45) attached to the opposite end of this area, with this sixth pinion (45) being arranged above the servomotors (25, 47). The servomotors are arranged below the roof (39) of the cross member (40) covering the spindle holder (18), with the cross member (40) itself being fastened to the machine roof (11) of the machine tool.

The fifth pinion (37) rotatably arranged on the main drive shaft (29) is connected to a pinion on the drive shaft (46) of the

Servomotor (47) is in engagement with the seventh pinion (49) which is rotatably mounted by means of a roller bearing (48). Between this seventh pinion (49) and the roof (39) of the cross member (40), a coupling half (50) is rotatably mounted coaxially with the aid of a roller bearing (51) on the output shaft (46) with the seventh pinion (49), e.g. integrally connected. Between the coupling half (50) and the roof (39) of the cross member (40), a second coupling half (52) is fixedly mounted on the output shaft (46), e.g. by means of a feather key (53). The seventh pinion (49) is in use with the second pinion (19b) which is mounted on the work spindle (19).

The collar (20) of the spindle holder (18), which is designed as a worm wheel with external teeth, is acted upon by a worm (54) which can be driven by a motor (not shown) in such a way that the spindle holder (18) can be alternately pivoted by 180°. This drive motor is attached to the machine roof (11) of the machine tool in a manner not shown. Instead of the worm wheel (20), a cam disk which executes a 180° pivoting movement in a sinusoidal curve can also be mounted (not shown).

When the machining tool (13) or (14) inserted into the tool holder (21 a) or (21 b) of one of the two work spindles (19', 19") correspondingly machines the supplied workpiece (55), the machining tool (13) or (14) previously used is fully automatically removed from the tool holder (21 a) or (21 b) and fed back into a known magazine chain (57) for storing e.g. machining tools, whereby a new machining tool for the next operation is then removed from the magazine chain (57) and inserted into the tool holder

(21 a) or (21 b) of the second work spindle (19') or (19"). The magazine chain (57) is for this purpose fastened below the machine roof (11) of the machine tool. Likewise, a known tool turning station (56) in the form of a so-called "double gripper" is fastened in the area of the machine roof (11) of the machine tool. The tool turning station (56) is arranged so that it can be moved in height, with its grippers (65) for the processing tools being arranged so that they can be pivoted radially by 180°.

The receiving device (58) for the workpiece (55) to be machined has five movable axes, whereby three axes are formed by correspondingly movable slides. A first slide (59) can be moved in the longitudinal direction of the machine tool and carries a second slide (60) that can be moved in the transverse direction. The transverse slide (60) in turn carries a third slide (61) that can be moved in height. On the surface side of the third slide (61) that can be moved in height and faces the spindle holder (18) and runs perpendicular to the installation floor of the machine tool, a disk (62) that rotates about its horizontal axis is arranged. On the surface side of the disk (62) that faces the spindle holder (18) and runs perpendicular to the installation floor of the machine tool, a tool holder is arranged.

(63) on which the actual workpiece holder

(64) is arranged to rotate about its vertical axis. The workpiece is therefore fed to the respective machining tool in the necessary corresponding machining position by means of these five movable axes.

The working sequence of the machine tool with the changing device according to the invention is described as follows:

A tool (14) machining the workpiece (55) is clamped into the tool holder (21 a) of the work spindle (19'). The sixth pinion (45) of the main drive shaft (29) is driven by a drive motor (68) via a toothed belt (67). The two coupling halves (42 and 43) are not in engagement with one another; however, the lower coupling halves (33 and 34) are in engagement with one another, which can thus drive the third pinion (23 a) on the drive shaft (23) of the servomotor (25), which in turn can drive the first pinion (19 a) on the work spindle (19), whereby this - and thus the machining tool itself - is set in a rotary motion necessary for machining or the like. The two coupling halves (24 and 27) on the drive shaft (23) of the servomotor (25) are not in engagement with one another, since the servomotor (25) only needs the two coupling halves (24 and 27) in an interconnected form for the precise positioning of the corresponding work spindle (19). The coupling halves (24, 27) on the drive shaft (23) of the servomotor (25) are not in engagement with one another, in contrast to the two coupling halves (50, 52) on the drive shaft (46) of the servomotor (47). This makes it possible for the servomotor (47) to position the corresponding work spindle (19 ¹ or 19") via the seventh pinion (49) in such a way that the gripper (6 5) can grasp the tool that was previously in use by raising it, pull it out of the tool holder (21 a) or (21 b) by lowering it and then move it back into the area of the magazine chain (57) by swiveling it through 180°. The machining tool is then inserted into an empty magazine of this magazine chain (57) by raising it. The gripper (65) moves down again, the magazine chain (57) continues to cycle until the next tool to be used is in the removal position required for the gripper (57).

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position. The gripper (57) moves up, grasps this new processing tool that is to be used, moves back down to its starting position, swivels through 180°, moves up again and inserts the new tool that is to be used into the tool holder (21 a) or (21 b) of the corresponding work spindle (19') or (19") and then moves back down to its old starting position.

Once the tool has finished machining the workpiece, the workpiece moves out of the tool's machining area. After the spindle holder (18) has been released by a so-called index bolt (66) inserted from the outside into the crossbeam (40), the spindle holder (18) is swiveled by 180° by the worm (54) driven by a motor (not shown) that is in engagement with the external toothing of the collar (20). During this swiveling process, the main drive motor (68) takes over the main braking work for the work spindle that was just in engagement. When a minimum speed of this work spindle is reached, the two lower coupling halves (33, 34) on the main drive shaft (29) are released, then the two coupling halves (24, 27) on the output shaft (23) of the servomotor (25) close, whereby the two coupling halves (24, 27) are now engaged with each other. The servomotor (25) can now begin the positioning work described above for the corresponding work spindle (19', 19").

When the two lower coupling halves (33, 34) on the main drive shaft (29) are opened, the two upper coupling halves (42, 43) also close at the same time; the two coupling halves (50, 52) on the output shaft (46) of the servomotor (47) both disengage and the main drive motor (68) starts to run again until it reaches

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a desired maximum number of revolutions of the tool.

A further tool change with subsequent swiveling of the spindle holder (18) and corresponding opening and closing of the individual coupling halves or the positioning of the corresponding work spindle by the servomotors (25 or 47) can be carried out in reverse order - analogous to the description given above.

In addition to the advantages of the described machine tool with changing device for machining tools to be accommodated, such as short times for tool changes from "chip to chip", since the cutting time is used for tool changes, as well as an associated longer service life of the work spindles (19 ¹ , 19") and less heating of the work spindles (19', 19") due to shorter working times, there is also the fact that after the tool change process the newly inserted tool is checked for "breakage":

A touch plate (69) is moved under the tool (13) by means of a spindle (70) via a servomotor (71) attached to the machine roof (11), which is equipped with a measuring system. When the touch plate (69) touches the tool (13), an initiator (72) switches off the servomotor (71). The distance traveled by the touch plate (69) is now compared with the measuring distance that would have to be traveled with a known tool length. If the measuring system has determined the specified measuring path, the tool also has the correct length, i.e. there is no "tool breakage". However, if the touch plate (69) is moved beyond the stop point on the tool (13), the specified measuring path is exceeded, a "tool breakage" occurs and the machine automatically switches to fault mode.

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The great advantage of the invention is that the machine makes the machining tool available for machining again as quickly as possible (e.g. within 3 seconds) when a tool is changed, which is achieved by the fact that the tool change times and the tool length measurement to determine a "tool breakage" fall entirely within the machining time of the machine and thus do not count as unproductive cycle times.

Claims (17)

Protection claims 1. Device for changing at least two machining tools by means of an associated changing device, characterized by a block (18) with several work spindles (19 ^' , 19") arranged at a distance from one another, each equipped with a tool holder and carrying out a back and forth pivoting movement, with several pinion groups which can alternately drive each work spindle (19', 19"), each of which is assigned an output shaft (23, 46) which is coupled to a servomotor (25, 47) and can be switched on and off by means of intermediate clutches (24, 27, 50, 52), and wherein each pinion group is assigned a main clutch (42, 43). 2. Device according to claim 1, characterized in that the inserted block (18) carries on the top of a collar (20) a gear, a worm wheel or the like, which is coupled to a drivable rack, a worm (54) or the like. 3. Device according to one of claims 1 or 2, characterized in that the couplings (24, 27, 50, 52) are designed as magnetic couplings. 4. Device according to one of claims 1 to 3, characterized in that a pinion (31, 37) is attached at a distance from one another on a main drive shaft (29) which forms a central pivot axis of the block (18). 5. Device according to one of claims 1 to 4, characterized in that the block (18) is removably mounted on roller bearings (16) on the machine roof (14). 6. Device according to one of claims 1 to 5, characterized in that the block (18) is releasably secured by means of removable locking bolts (66). 7. Device according to one of claims 1 to 6, characterized in that the two working spindles (19', 19") are arranged in the spindle holder (18) at a distance from one another and - viewed in the longitudinal direction of the machine tool - in alignment with one another. 8. Device according to one of claims 1 to 7, characterized in that the main drive shaft (29) runs coaxially in the block and is rotatably mounted therein. 9. Device according to one of claims 1 to 8, characterized in that a magazine chain (57) with tools is arranged in the region of the spindle holder which is not in the machining position. 10. Device according to one of claims 1 to 9, characterized in that the magazine chain (57) is mounted so as to cooperate with a turning station (56). 11. Device according to one of claims 1 to 10, characterized in that the tool turning station (56) is movable in height and the tool gripper (65) arranged thereon is mounted so as to be alternately radially pivotable. 12. Device according to one of claims 1 to 11, characterized in that the receiving device (58) and the workpiece to be machined (55) have five movable axes, of which three axes are formed by correspondingly movable slides (59, 60, 61). 13. Device according to one of claims 1 to 12, characterized in that a disk (62) rotating about its horizontal axis is arranged on the third carriage (61). 14. Device according to one of claims 1 to 13, characterized in that a tool holder (63) is fastened to the surface side of the disk (62), on which the workpiece holder (64) is arranged so as to be rotatable about its vertical axis. 15. Device according to one of claims 1 to 14, characterized in that a test device scanning the tool in the rest position is equipped with a touch plate (69). 16. Device according to one of claims 1 to 15, characterized in that the touch plate (69) is coupled in a switching manner to an initiator (72) of the servomotor (71). 17. Device according to one of claims 1 to 16, characterized in that the displaceable touch plate (69) is equipped with a measuring section.