MACHINE TOOL FOR THE MACHINING OF ROTARY PARTS WITH GROOVE-LIKE PROFILES BY A GENERATING METHOD

Abstract

A machine tool is designed for the machining of rotary parts with groove-shaped profiles, in particular gears, by a generating method. On the one hand, a Y slide (200) is arranged on a machine bed (100), the Y slide being displaceable along a Y direction and carrying a workpiece spindle (210). The workpiece spindle drives a workpiece (220) to rotate about a workpiece axis (C). On the other hand, a Z slide (300) is arranged on the machine bed. The Z slide is arranged along a Z direction running parallel to a center plane (E1) spanned by the Y direction and the workpiece axis. An X slide (310) is arranged on the Z slide and can be displaced along an X direction relative to the Z slide (300). The X direction is perpendicular to the center plane. A tool spindle (320) is arranged on the X slide, which drives a tool to rotate about a tool axis. The tool spindle can be swiveled relative to the X slide in a swivel plane (E2), which runs parallel to the center plane, about a swivel axis (A).

Claims

1. A machine tool for the machining of rotary parts with groove-shaped profiles by a generating method, the machine tool comprising: a machine bed; a Y slide linearly displaceable along a Y direction relative to the machine bed; a workpiece spindle arranged on the Y slide and configured to clamp a workpiece thereon and to drive it to rotate about a workpiece axis (C), the workpiece axis (C) extending transversely to the Y direction; a Z slide arranged on the machine bed and linearly displaceable along a Z direction relative to the machine bed, the Z direction running parallel to a center plane defined by the Y direction and the workpiece axis, and the Z direction extending at an angle of less than 45° to the workpiece axis; an X slide arranged on the Z slide and linearly displaceable along an X direction relative to the Z slide, the X direction being perpendicular to the center plane; and a tool spindle configured to drive a generating machining tool about a tool axis, the tool spindle being arranged on the X slide and being pivotable relative to the X slide about a first swivel axis.

2. The machine tool according to claim 1, wherein the first swivel axis is perpendicular to the center plane, wherein the tool axis is perpendicular to the first swivel axis, and wherein the tool spindle is pivotable about the first swivel axis in a swivel plane that extends parallel to the center plane.

3. The machine tool according to claim 2, wherein the machine tool comprises two first swivel bearings for pivotably supporting the tool spindle on the X slide about the first swivel axis, wherein the two first swivel bearings are arranged on both sides of the tool spindle with respect to the swivel plane.

4. The machine tool according to claim 2, comprising an adjustment mechanism for adjusting the orientation of the tool spindle relative to the X slide, wherein the adjustment mechanism is connected to the X slide so as to be pivotable about a second swivel axis, the second swivel axis extending parallel to and spaced apart from the first swivel axis-(A), and wherein the adjustment mechanism is connected to the tool spindle so as to be pivotable about a third swivel axis, the third swivel axis extending parallel to and spaced apart from the first swivel axis and the second swivel axis.

5. The machine tool according to claim 4, wherein the machine tool comprises two second swivel bearings for pivotably supporting the adjustment mechanism on the X slide about the second swivel axis, wherein the two second swivel bearings are arranged on both sides of the swivel plane, and/or wherein the machine tool comprises two third swivel bearings for pivotably supporting the adjustment mechanism on the tool spindle about the third swivel axis, wherein the two third swivel bearings are arranged on both sides of the swivel plane.

6. The machine tool according to claim 4, wherein the adjustment mechanism comprises: an A-drive motor, which is mounted on the X slide so as to be pivotable about the second swivel axis a threaded spindle drivable by the A-drive motor to rotate about a threaded spindle axis extending perpendicular to the first swivel axis, the threaded spindle axis extending in the swivel plane; and a spindle nut which is in engagement with the threaded spindle (342) and is connected to the tool spindle (320) so as to be pivotable about the third swivel axis (A″).

7. The machine tool according to claim 6, comprising: a first angle measuring device configured to determine a rotation angle of the threaded spindle about the threaded spindle axis; and/or a second angle measuring device configured to directly determine a swivel angle of the tool spindle about the first swivel axis relative to the X slide.

8. The machine tool according to claim 4, wherein the tool spindle has an end that faces the tool and an end that faces away from the tool, wherein a generating machining tool is clamped on the tool spindle at the end that faces the tool, the generating machining tool defining a tool reference plane, the tool reference plane extending perpendicularly to the tool axis, wherein the first swivel axis intersects the tool axis between the end of the tool spindle that faces the tool and the end that faces away from the tool, wherein the first swivel axis and the tool reference plane extend at a first distance from each other, wherein the first swivel axis and the third swivel axis extend at a second distance from each other, and wherein the second distance and the first distance have a ratio greater than 1.

9. The machine tool according to claim 1, comprising: at least one vibration damper acting between the tool spindle and the X slide in order to damp vibrations of the tool spindle about the first swivel axis.

10. The machine tool according to claim 1, wherein the tool spindle is pivotable relative to the X slide about the first swivel axis in such a manner that an axis crossing angle between the tool axis and the workpiece axis is able to takes on negative and positive values between a smallest negative value and a maximum positive value, and wherein the maximum positive value of the axis crossing angle is greater than a magnitude of the smallest negative value.

11. The machine tool according to claim 1, wherein the workpiece axis runs vertical in space.

12. The machine tool according to claim 1, wherein the machine tool comprises two mutually parallel Z linear guides on which the Z slide is guided along the Z direction relative to the machine bed, the Z linear guides extending parallel to the Z direction and being arranged on both sides of the center plane, wherein the machine tool comprises two Z-drives for moving the Z slide along the Z direction relative to the machine bed, and wherein each of the Z-drives is assigned to one of the Z linear guides.

13. The machine tool according to claim 12, comprising at least one, preferably two Z linear measuring systems, each of the Z linear measuring systems comprising a measuring head mounted on the Z slide and a linear scale mounted on the machine bed, and wherein the measuring heads of the Z linear measuring systems are arranged such that they carry out a position measurement in an A-reference plane which is perpendicular to the Z direction and contains the first swivel axis.

14. The machine tool according to claim 1, wherein the machine tool comprises two parallel Y linear guides which extend parallel to the Y direction, are arranged on both sides of the center plane and on which the Y slide is guided along the Y direction relative to the machine bed, wherein the machine tool comprises two Y drives for moving the Y slide along the Y direction relative to the machine bed, and wherein in each case one of the Y drives is assigned to each of the Y linear guides.

15. The machine tool according to claim 14, comprising at least one Y linear measuring system, each Y linear measuring systems comprising a measuring head mounted on the Y slide and a linear scale mounted on the machine bed, and wherein the measuring heads of the Y linear measuring systems are arranged in such a way that they perform a position measurement in a C reference plane which is perpendicular to the Y direction and contains the workpiece axis.

16. The machine tool according to claim 1, wherein the machine tool comprises at least one of the following additional components: a meshing device for determining a position of tooth gaps of the workpiece; an optical measuring bridge for measuring the workpiece and/or the tool; and a tool changing device for changing the tool, and wherein the machine tool has two alternative fastening structures for each of the additional components, the alternative fastening structures being arranged on both sides of the center plane.

17. The machine tool according to claim 1, wherein the machine tool comprises a chip conveyor, and wherein the machine bed has a central opening to allow discharge of chips onto the chip conveyor.

18. The machine tool according to claim 1, comprising a controller configured to establish a positive coupling between a rotation of the generating machining tool and a rotation of the workpiece.

19. A method of machining a workpiece with a machine tool according to claim 1, the method comprising: bringing a generating machining tool clamped on the tool spindle into engagement with the workpiece while the workpiece is clamped on the workpiece spindle, wherein the engagement takes place in an arrangement of the generating machining tool relative to the workpiece in which the tool axis extends offset to the center plane of the machine tool; and carrying out a generating machining operation on the workpiece with the machine tool.

20. The method according to claim 19, wherein the generating machining tool is gear-shaped.

21. The method according to claim 19, wherein the generating machining tool is a gear skiving tool.

22. The machine tool according to claim 1, wherein the workpiece axis extends perpendicularly to the Y direction.

23. The machine tool according to claim 1, wherein the Z direction extends parallel to the workpiece axis.

24. The machine tool according to claim 2, wherein the first swivel axis intersects the tool axis.

25. The machine tool according to claim 3, wherein the two first swivel bearings are equidistant from the swivel plane.

26. The machine tool according to claim 8, wherein the generating machining tool is gear-shaped.

27. The machine tool according to claim 8, wherein the generating machining tool is a gear skiving tool.

28. The machine tool according to claim 8, wherein the generating machining tool comprises a plurality of cutting edges arranged at a distal end of the tool, and wherein the tool reference plane extends through the cutting edges of the tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for explanatory purposes only and are not to be interpreted as limited. In the drawings:

[0065] FIG. 1 shows a perspective view of a machine tool according to a first embodiment:

[0066] FIG. 2 shows an enlarged detailed view in area A1 in FIG. 1;

[0067] FIG. 3 shows a sectional view of the machine tool in FIG. 1 in the center plane E1;

[0068] FIG. 4 shows an enlarged detailed view in area A2 in FIG. 3;

[0069] FIG. 5 shows a perspective view of the machine tool in FIG. 1, leaving out parts in the area of the X slide; and

[0070] FIG. 6 shows a perspective view of a machine tool according to a second embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

First Embodiment: Vertical Workpiece Axis

[0071] FIGS. 1 to 4 show in different views a machine tool according to a first embodiment. In FIG. 5, parts of the machine are not shown for better visibility, especially the front part of the Z slide and the entire X slide with the tool spindle mounted on it.

[0072] The illustrated machine tool is a machine which is particularly suitable for gear skiving. However, it is also possible to carry out other types of machining processes with such a machine, especially other generating machining processes.

[0073] The machine comprises a machine bed 100. As can best be seen in FIG. 3, the machine bed 100 is approximately L-shaped in a side elevation, having a horizontal portion 110 and a vertical portion 120. The vertical portion of the machine bed 120 separates a front machining area 130 from a rear area 140 of the machine.

[0074] A Y slide 200 is arranged on the horizontal portion 110 of the machine bed 100. The Y slide can be displaced along a Y direction relative to the machine bed 100. The Y direction runs horizontally in space. The Y slide 200 carries a workpiece spindle 210, on which a pre-toothed workpiece 220 is clamped. The Y slide 200 thus serves as a workpiece carrier. The workpiece 220 is driven on the workpiece spindle 210 so that it can rotate about a workpiece axis (C axis). The C axis runs vertically in space, i.e. along the direction of gravity. The C axis and the Y direction together span a center plane E1 of the machine. The center plane E1 contains the C axis, independent of the position of the Y slide 200 along the Y direction.

[0075] A Z slide 300 is arranged on the vertical portion 120 of the machine bed 100. The Z slide can be moved along a Z direction relative to the machine bed 100. The Z direction is parallel to the center plane E1. In the present example, the Z direction runs vertically in space, parallel to the C axis and perpendicular to the Y direction. An X slide 310 is arranged on the Z slide 300, the X slide carrying a tool spindle 320 and thus forming a tool carrier. The X slide 310 can be displaced along an X direction relative to the Z slide 300. The X direction runs horizontally in space, perpendicular to the Z direction and the Y direction and thus perpendicular to the center plane E1. Together, the Z slide 300 and the X slide 310 form a compound slide rest that enables the tool spindle 320 mounted on it to be moved along the Z and X directions, which are perpendicular to each other.

[0076] The tool spindle 320 drives a generating machining tool mounted on it, in the present case a gear skiving tool 330 (“hob peeling wheel”, see FIGS. 3 and 4), to rotate about a tool axis (B axis, see FIG. 4). The tool spindle 320 can be swiveled about a first swivel axis (A axis, see FIG. 2) in relation to the X slide 310. The A axis is perpendicular to the B axis and perpendicular to the center plane E1. The A axis intersects the B axis. The plane in which the B axis swivels is referred to as the swivel plane E2. This swivel plane E2 is perpendicular to the A axis (i.e. it is a normal plane to the A axis) and contains the B axis, regardless of its swivel position about the A axis. It is parallel to the center plane E1.

[0077] A chip conveyor 500 is arranged below and behind the machine bed 100 in such a way that it conveys chips from an area below the Y slide 200 to the rear area 140 of the machine. The chip conveyor 500 has a drive 510 for this purpose. Below the Y slide 200, an opening is arranged in the machine bed 100 for the discharge of the chips produced. Alternatively, the chip conveyor 500 can be arranged so that it conveys the chips to the front instead of to the rear.

[0078] A machine controller with control panel 600 is used to control and operate the machine.

Setting the Orientation of the Tool Spindle Around the A Axis

[0079] When carrying out generating machining operations, it is important that the orientation of the tool spindle 320 about the A axis can be precisely adjusted. For this purpose, the machine is equipped with an appropriate adjustment mechanism.

[0080] FIGS. 2 and 4 show the swivel-mounted tool spindle 320 and the adjustment mechanism for adjusting the orientation of the tool spindle 320 around the A axis. The X slide 310 has a side wall (“cheek”) 313 on each side of the swivel plane E2, which extends parallel to the swivel plane E2 and forwards against the Y direction. A sufficiently large recess for the tool spindle 320 is provided between the two cheeks 313. The tool spindle 320 is located between the cheeks 313 in the swivel plane E2 and is supported in the corresponding cheek 313 via a swivel bearing 314 in the form of a play-free rolling bearing. The two swivel bearings 314 enable the tool spindle 320 to swivel relative to the X slide 310 about the first swivel axis (A axis).

[0081] In an upper end area of the X slide 310, an A drive motor 340 is arranged centrally between the cheeks 313. The A drive motor is mounted on both sides of the swivel plane E2 in two play-free rolling bearings 315 so that it can swivel on the X slide 310 about a second swivel axis A′. The second swivel axis A′ runs parallel to the A axis. The A drive motor 340 drives a threaded spindle 342 to rotate about a threaded spindle axis 343. The threaded spindle 342 cooperates with a spindle nut 344. The threaded spindle 342 and the spindle nut 344 are configured as a play-free ball screw drive.

[0082] The spindle nut 344 is connected on both sides of the swivel plane E2 to an upper end section of the tool spindle 320. The spindle nut 344 can be swiveled about a third swivel axis A″ relative to the tool spindle 320 via two play-free rolling bearings 325. The third swivel axis A″ is again parallel to the A axis.

[0083] By actuating the A drive motor 340, the threaded spindle 342 is driven to rotate about the threaded spindle axis 343. This changes the position of the spindle nut 344 along the threaded spindle axis 343. This causes the tool spindle 320 to swivel about the A axis. Due to the high transmission ratio, a relatively low drive torque of the A drive motor 340 is converted into a relatively high displacement force or a relatively high swivel torque onto the tool spindle 320. All in all, the swivel movement of the tool spindle 320 can thus be executed very smoothly and precisely. Even during machining, it is possible to change the orientation of the tool spindle 320. Clamping for stationary operation is not necessary.

[0084] The geometrical conditions prevailing here are explained in more detail in FIG. 4. The A axis (see FIG. 2) intersects the B axis in a region that lies between the end of the tool spindle 320 that faces the tool and the end that faces away from the tool. The tool 330 has a number of cutting edges at its free end, which together define a cutting edge plane 331. This cutting edge plane 331 is a reference plane on the tool. The cutting edge plane 331 is perpendicular to the B axis. The distance of the cutting edge plane 331 from the A axis defines a lever arm H. The distance between the A axis and the third swivel axis A″, about which the spindle nut 344 can be swiveled, defines a swivel radius R.

[0085] The radial cutting forces that act between the workpiece and the tool during workpiece machining result in corresponding torques about the A axis. The torque about the A axis for a given radial cutting force in the swivel plane E2 is proportional to the length of the lever arm H. This torque in turn results in a corresponding axial force on the spindle nut 344 along threaded spindle axis 343. This force is smaller the larger the swivel radius R. In the present case, the swivel radius R is significantly larger than the lever arm H. Preferably, the ratio R/H is larger than 1 and lies in particular between 1.5 and 3. The A drive motor 340 therefore only needs to absorb correspondingly reduced forces. This is advantageous for the rigidity of the machine with regard to vibrations about the A axis.

[0086] To dampen vibrations about the A axis, additionally two vibration dampers 346 are arranged between the tool spindle 320 and the X slide 310. These extend on both sides of the swivel plane E2 between the upper end section of the tool spindle 320 and the upper end section of the X slide 310, adjacent to threaded spindle 342.

[0087] For precise machining of the workpiece in a generating machining process such as the gear skiving process, precise knowledge of the orientation of the tool spindle 320 about the A axis, i.e. of the angle α between the B axis and the C axis (see FIG. 4), is important. The angle α is also referred to in this document as the axis crossing angle. The machine preferably features two independent angle measuring devices for precise measurement of this angle. One of the angle measuring devices measures the angle of rotation of the threaded spindle 342, this information can be used to indirectly determine the position of the spindle nut 344 along the threaded spindle 342 and therefore the tilt angle of the tool spindle 320. This first angle measuring device is integrated in the A drive motor 340 and is indicated in FIG. 2 by reference sign 347. At least one other angle measuring device measures directly the tilt angle of tool spindle 320 about the A axis and therefore the axis crossing angle α. This further angle measuring device is integrated in one of the two swivel bearings 314 and indicated by reference sign 323 (see FIG. 2).

[0088] As illustrated in FIG. 4, the axis crossing angle α can assume both positive and negative values. The axis crossing angle α is defined as positive when the tool 330 is inclined toward the X slide 310 and negative when the tool 330 is inclined away from the X slide 310. The swivel range of the tool spindle 320 is asymmetrical: The axis crossing angle α can assume significantly larger positive than negative values. Specifically, the swivel range can be from −5° to +35°, but other swivel ranges are also possible. Due to the almost mirror-symmetrical design of the machine with respect to the center plane E1, this does not mean that the generating machining process is restricted to only one helix direction of the gear to be machined, because depending on the helix direction, the tool 330 can be brought into engagement with the gear to be machined either to the left or right of the center plane E1.

Positioning of the Tool Carrier in Z and X Direction

[0089] As already mentioned, the machine is designed in such a way that the position of the tool spindle 320 is adjustable both along the Z direction and along the X direction. The Z displacement is used for axial feed and the X displacement or a combination of X and Y displacements for radial infeed in generating machining. Since machining forces fluctuate particularly strongly along the Z direction, the adjustment along the Z direction is carried out with a Z slide 300 that is guided directly on the machine bed 100; the X slide 310 is mounted on this Z slide as a tool carrier. This means that a much greater inertial mass needs to be moved along the Z direction than along the X direction. This helps to keep the amplitude of vibrations along the Z direction, which might be excited by the fluctuating machining forces, small.

[0090] In order to guide the Z slide 300 relative to the machine bed 100, two parallel Z linear guides 301 are provided on the vertical portion 120 of the machine bed, extending parallel to the Z direction and being arranged on both sides symmetrically to the center plane E1. The Z slide 300 is guided on these linear guides 301 along the Z direction relative to the machine bed 100. Each of the linear guides 301 is assigned a Z drive motor 302. Each of these Z drive motors 302 interacts with the Z slide 300 via a play-free ball screw drive 303 to drive the Z slide 300 along the Z direction (see FIG. 5). The Z linear guides 301, Z drive motors 302 and ball screw drives 303 are each constructed almost identically in pairs and arranged symmetrically to each other with respect to the center plane E1. The two Z drive motors are either separately position-controlled (“double drive”) or work together in master-slave operation.

[0091] In order to dampen vibrations along the Z direction, each Z linear guide 301 is optionally assigned a vibration damper not shown in the drawing. This vibration damper can be configured in particular according to Swiss patent application 1023/18 of Aug. 24, 2018. The vibration dampers are also identically constructed in pairs and arranged symmetrically.

[0092] Each of the two Z linear guides 301 is assigned a Z linear measuring system 350 in order to determine the position of the Z slide 300 on the machine bed 100 as accurately as possible (see FIG. 3). The two Z linear measuring systems 350 are also identically constructed and arranged symmetrically with respect to the center plane E1. Each of these Z linear measuring systems has a measuring head 351, which is attached to an outer surface of the Z slide 300. In addition, each Z linear measuring system has a linear scale 352 attached to the machine bed 100. The measuring head 351 is mounted so that it performs a position measurement in a plane E4 that is perpendicular to the Z direction (i.e. a plane normal to the Z direction) and contains the A axis. This plane E4 is particularly suitable for characterizing the position of the A axis relative to the machine bed 100 with respect to the Z direction and is therefore also referred to as the A reference plane.

[0093] In order to guide the X slide 310 on the Z slide 300, two X linear guides 311 are provided on the Z slide 300, parallel to each other, which extend parallel to the X direction and on which the X slide 310 is guided along the X direction relative to the Z slide. An X drive motor 312 is used to adjust the position of the X slide 310 along the X direction.

Positioning of the Workpiece Carrier in Y-Direction

[0094] The guidance and displacement of the Y slide 200 (i.e., the workpiece carrier) relative to the machine bed 100 along the Y direction is very similar to the guidance and displacement of the Z slide 300 along the Z direction. On the horizontal portion of the machine bed 100, two parallel Y linear guides 201 are arranged symmetrically to the center plane E1. The Y slide 200 runs on these linear guides 201. To drive the Y slide 200, a separate Y drive motor 202 is assigned to each of the two linear guides 201 (see FIG. 3). Each of the Y drive motors 202 interacts with the Y slide 200 via a play-free ball screw drive 203. Again, the Y drive motors 202 can be separately position-controlled or operated in master-slave mode. In order to dampen vibrations along the Y direction, each linear guide 201 is optionally assigned a vibration damper (not shown in drawings), which can be configured according to Swiss patent application 1023/18 dated Aug. 24, 2018.

[0095] Each of the two linear guides 201 is assigned a Y linear measuring system 230. Each of these Y linear measuring systems comprises a measuring head 231 mounted on the outside of the Y slide 200 and a linear scale 232 mounted on the machine bed 100. The measuring head 231 carries out its position measurement in a plane E3 that is perpendicular to the Y direction (i.e. a plane normal to the Y axis) and contains the C axis. This plane E3 is particularly suitable for characterizing the position of the C axis relative to the machine bed 100 with respect to the Y direction and is therefore also referred to as the C reference plane.

[0096] As with the Z axis, all relevant components of the Y axis are identical in pairs and arranged symmetrically to the center plane E1, in particular the Y linear guides 201, the Y drive motors 202, the ball screw drives 203, the vibration dampers and the Y linear measuring systems 230.

Meshing Device

[0097] For the hard fine machining of pre-toothed workpieces, a meshing device 410 is arranged on the X slide 310, which is configured to determine the angular position of the tooth gaps of the workpiece 220 with respect to the C axis without contact, so that the tool 330 can be brought into engagement with a pre-toothed workpiece 220 without collision. For this purpose, the meshing device 410 has a meshing probe 411 arranged at its lower end, which measures the tooth gaps in a known manner. The single meshing device 410 can be attached to either of the two cheeks 313 of the X slide 310. For this purpose, the two cheeks have mounting surfaces 412 with corresponding holes on the front side (see FIG. 2).

Measuring Bridge

[0098] In FIG. 3, an optical measuring bridge 420 can be seen particularly well, which is mounted on the Y slide 200 and is used to measure the tool 330. In particular, the measuring bridge can be a laser measuring bridge with laser and photodetector. The measuring bridge 420 can be located either to the left or right of the center plane E1 on the workpiece carrier 200. For this purpose, corresponding mounting surfaces 421 with corresponding holes are provided on the Y slide 200 to the left and right of the center plane E1 (see FIG. 4). The tool can be measured in particular according to WO 2019/115332 A1.

Tool Changer

[0099] FIG. 5 schematically shows a changing device 430 for the automatic changing of the tool. The changing device is attached to the machine bed 100 and can also be arranged either to the left or right of the center plane E1. For this purpose, corresponding mounting surfaces 431 and holes are provided on the machine bed 100.

Workpiece Loader

[0100] As shown in FIG. 5, the machine is optionally equipped with a workpiece loader 440. The workpiece loader can remove a finished workpiece 220 from the workpiece spindle 210 and replace it with a blank to be machined, or it can exchange the workpiece clamping device. Depending on the customer's requirements, the workpiece loader 440 can be located to the left or right of the center plane E1.

[0101] To avoid collisions with the meshing device 410, the measuring bridge 420 or the tool changer 430 during the workpiece change, these additional components are arranged either to the left or right of the center plane E1, depending on the position of the workpiece loader 440. The corresponding arrangement will be determined during the project planning phase of the machine according to the customer's requirements.

[0102] Alternatively, the workpiece loader can also be positioned at the front end of the machining area 130 in the center plane E1, as also indicated in FIG. 5. If desired, it is also possible to arrange the workpiece loader at the rear of the machine so that the loading and unloading process takes place through an opening in the vertical portion 120 of the machine bed. For this purpose, the chip conveyor 500 is arranged rotated by 180° relative to the arrangement of FIGS. 1 to 6, so that its rising section with the drive comes to rest at the front end of the machining area 130. Due to the limited accessibility, however, this arrangement of the workpiece loader is only useful in exceptional cases.

Second Embodiment: Horizontal Workpiece Axis

[0103] While the machine of the first embodiment has a vertically aligned workpiece axis C, it is also conceivable to align the workpiece axis C horizontally without deviating from the principles described above. This is illustrated in FIG. 6. Equal-acting parts carry the same reference signs as in FIGS. 1 to 5.

[0104] Again, the machine bed 100 has a horizontal portion 110 and a vertical portion 120. Unlike in the first embodiment, the Y slide 200, which serves as a workpiece carrier, can now be displaced vertically on the vertical portion 120, i.e. the Y direction is now vertical. Accordingly, the C axis now runs horizontally. As before, the C axis runs in a center plane E1, and the Y slide 200 on the machine bed 100 is guided symmetrically to the center plane by two linear guides. The Z slide 300 can now be moved horizontally on the horizontal portion 110 of the machine bed 100 parallel to the C axis, i.e. the Z direction is now horizontal. The Z slide is again guided symmetrically to the center plane by two linear guides. The X slide 310, which serves as the tool carrier, is arranged on the Z slide 300 as in the first embodiment. It is constructed in the same way as in the first embodiment.

Method of Operation

[0105] A method of operation for a machine according to the first embodiment (FIGS. 1 to 5) is now discussed.

[0106] In order to machine a workpiece blank, the Y slide 200 is first brought into a workpiece change position against the Y direction, the workpiece change position being illustrated in FIGS. 1 to 3. In this position, the workpiece loader 440 is used to remove the last finished workpiece 220 from the workpiece spindle 210 and the workpiece blank to be machined is placed on the workpiece spindle 210 and clamped. Then the Y slide 200 is moved along the Y direction to a machining position as illustrated in FIG. 5.

[0107] In the case of hard fine machining, the Z slide 300 and the X slide 310 are now positioned in such a way that the meshing device can measure the tooth gaps of the blank. In this way, the angular position of the tooth gaps of the blank is determined.

[0108] The Z slide 300 and the X slide 310 are then brought into a position in which the tool 330 meshes with the blank, as illustrated in FIG. 5. The B axis extends offset either to the left or to the right of the center plane of the machine tool, depending on the helix angles of the workpiece and the tool. Now the generating machining of the blank is carried out in the usual way. The tool 330 and the workpiece 220 rotate at a fixed ratio of their rotational speeds. This positive coupling is carried out electronically by the machine controller.

[0109] If desired, the tool is measured with the aid of the measuring bridge 420. In the case of a gear skiving tool, this can be done, for example, in a manner described in WO 2019/115332 A1. Such measurement can be carried out, for example, after each tool change and periodically after a certain number of machining operations.

[0110] If the tool has to be changed, this is preferably done with the changing device 430.

Modifications

[0111] It goes without saying that the invention is not limited to the embodiments described above, but that various modifications are possible without leaving the scope of the invention.

[0112] For example, in the first embodiment, the Y direction can also be at an angle to the horizontal, but still parallel to the center plane E1. This may be advantageous under certain circumstances for design reasons or for reasons of loading and unloading the workpiece spindle. The Z direction does not necessarily have to be parallel to the C axis as long as this direction also remains parallel to the center plane E1. The symmetry of the machine is not destroyed by such modifications.

[0113] A variety of other modifications are possible. In particular, the machine can also be used for other generating machining processes than gear skiving. In this case, the tools that are typical for the respective process, preferably gearwheel-shaped tools, are used. Combinations of two or more machining processes can also be carried out successively on the same machine. It is conceivable, for example, that a workpiece is first processed by gear skiving and then by gear honing.

[0114] In addition to hard fine machining, the machine can also be used for soft machining, whereby only the meshing probe must be put out of operation and tools typical of the soft machining process are used.