Method for producing and/or processing a gear and gear cutting machine

Abstract

The invention concerns a method to generate and/or machine gear teeth on a workpiece, wherein the workpiece is subjected to a movement from a first location where the workpiece, while being held by a clamping device connected to a workpiece spindle, is brought into machining engagement with a first tool, to a second location where the work piece, while remaining in its clamped condition, is brought into machining engagement with a second tool, wherein prior to performing the movement, the connection between the clamping device and the workpiece spindle is released, and after the movement, the clamping device is connected to another workpiece spindle for the machining engagement with the second tool.

Claims

1. Method of generating and/or machining gear teeth on a workpiece (5), wherein the workpiece is subjected to a movement from a first location where the workpiece, while being held by a clamping device (3) connected to a workpiece spindle (1), is brought into machining engagement with a first tool (7), to a second location where the work piece, while remaining in its clamped condition, is brought into machining engagement with a second tool (8), characterized in that prior to performing the movement, the connection between the clamping device (3) and the workpiece spindle (1) is released, and after the movement, the clamping device (3) is connected to another workpiece spindle (2) for the machining engagement with the second tool (8).

2. Method according to claim 1, wherein in parallel with the machining of the workpiece at the second location, a gear tooth profile is being generated and or machined at the first location on a further workpiece (6) which is being held by a second clamping device.

3. Method according to claim 1 wherein the workpiece, subsequent to the machining with the second tool, is machined again with the first tool.

4. Method according to claim 1 wherein the respective location changes of the workpiece and of the further workpiece occur at the same time and are coupled to each other.

5. Method according to claim 4, wherein a machined workpiece, subsequent to the release of its clamping device, is taken out of the operating space without the clamping device, and/or a workpiece that is to be machined is connected to a clamping device only after said workpiece has been brought into the operating space.

6. Method according to claim 1 wherein a connector portion of the workpiece spindle to which the clamping device is connected during the machining of the workpiece at the respective location is covered during a time interval from the release of said connection until a new connection with a clamping device is made.

7. Method according to claim 1 wherein the respective machining engagements of the workpiece with the first and the second tool are determined by their respective mutual spatial positions, and wherein the setting of the mutual spatial position for the second machining engagement is dependent on the mutual spatial position in the first machining operation.

8. Gear-cutting machine (100) with at least two tools (7, 8) which are arranged in an operating space (20) for the generating and/or machining of gear teeth on a workpiece, and with at least two workpiece spindles (1, 2) serving to support workpieces (5, 6) that are held by respective clamping devices (3, 4) that are capable of rotation so that a first clamped workpiece (5) can be brought into machining engagement with a first tool (7) and, in parallel, a second clamped workpiece (6) can be brought into machining engagement with a second tool (8), characterized by a connector mechanism serving to release and to close a connection between a clamping device and a workpiece spindle, and a device that moves a workpiece from one workpiece spindle to another workpiece spindle while the workpiece remains connected to the clamping device.

9. Gear-cutting machine according to claim 8, wherein the workpiece-moving device comprises a holder (9a) for one of the clamping devices (4), which can swivel about a rotary axis (S) of the workpiece-moving device.

10. Gear-cutting machine according to claim 9, wherein the workpiece-moving device comprises at least one further holder (9a) which can swivel about the rotary axis, for a further clamping device (3), and wherein the movements of the holders are rigidly coupled to each other by a coupling connection (9r) between the holders (9a).

11. Gear-cutting machine according to claim 10, wherein the coupling is configured in the form of a common carrier for the holders (9a) which is rotatable about the rotary axis.

12. Gear-cutting machine according to claim 11 wherein the workpiece-moving device is designed with the capability to move a holder or the common carrier (9) with a directional component of the movement running parallel to at least one of the workpiece spindle axes.

13. Gear-cutting machine according to claim 8 with a covering device which, during at least part of a time interval from the release of said connection by the connecting mechanism until a new connection with a clamping device is made, covers up a connector portion of the workpiece spindle to which the clamping device is connected during the machining of the workpiece at the respective location.

14. Gear-cutting machine according to claim 11, wherein the covering device is coupled to a holder (9a) to move in tandem, with the latter, and wherein the covering device is formed by a portion (9r) of the common carrier (9).

15. Gear-cutting machine according to claim 8 wherein the workpiece spindles (1, 2) are arranged in a fixed position in space and their workpiece spindle axes are oriented vertically.

16. Gear-cutting machine according to claim 8 wherein the clamping connection of a workpiece to a clamping device that is in a connected state with a workpiece spindle is releasable by way of an actuating access created within the connector mechanism.

17. Gear-cutting machine according to claim 11 wherein the carrier additionally carries a tool that can be brought into machining engagement with at least one of the tools that serve for the machining of the workpiece.

18. Gear-cutting machine according to claim 8 wherein a clamping device comprises at least one mark through which the rotary position of the clamping device in relation to the workpiece spindle can be detected by a sensor.

19. Gear-cutting machine according to claim 8 wherein the connector mechanism allows a clamping device and a workpiece spindle to be connected to each other in only one defined relative rotary position or in a plurality of defined relative rotary positions by means of a form-fitting engagement acting in circumferential direction and/or by means of a rotary position lock between the holder and the clamping device which is effective during the position change.

20. Gear-cutting machine according to claim 8 further comprising a controller device, wherein the controller device acquires data defining the mutual spatial positions of a workpiece and a tool performing a machining operation in relation to each other, and keeps said data available for a subsequent machining operation with another tool.

21. Gear-cutting machine according to claim 8 wherein the first tool is a hob (7) and the second tool is a chamfering- and/or deburring tool (8), and wherein a third workpiece spindle which is assigned to a shaving station with a shaving tool is arranged within the operating space, wherein the workpieces are taken out of, or brought into, the operating space at the third workpiece spindle or at a fourth workpiece spindle.

Description

(1) Further distinguishing features, details and advantages of the invention will become evident from the following description which refers to the attached drawings, wherein

(2) FIG. 1 schematically represents portions of a gear-cutting machine according to the invention in a perspective view;

(3) FIG. 2 represents an axial section of the arrangement of FIG. 1;

(4) FIG. 3 represents an axial section that is analogous to FIG. 2, but in a different operating position;

(5) FIG. 4 represents an axial section of a detail area of FIG. 2;

(6) FIG. 5 shows portions of a gear-cutting machine according to a further embodiment of the invention;

(7) FIG. 6 shows portions of a gear-cutting machine according to a still further embodiment of the invention;

(8) FIG. 7 shows a tailstock arrangement, and

(9) FIG. 8 shows an axial section of a detail portion corresponding to an area of FIG. 7.

(10) FIG. 1 shows a first embodiment of the invention in a schematically simplified perspective view. The gear-cutting machine 100, shown here only in parts, is designed for the hobbing and also for a combined chamfering- and deburring operation of toothed workpieces. To perform these operations, the gear-cutting machine 100 has a milling head with a tool holder 17 carrying a hob 7 (indicated schematically) whose rotation is powered by a drive source. Although not shown in FIG. 1, the spatial position of the hob 7 is controlled along the machine axes that are conventionally used for hobbing, including in this case a vertical mobility, a horizontal mobility for a radial feed movement, an angular swiveling movement of the rotary axis of the hob 7 preferably about the feed axis, as well as a shifting movement of the hob along its axis of rotation.

(11) The operating space 20 of the gear-cutting machine 100 extends to a chamfering/deburring tool 8 which is rotatably supported in a holder 1. The chamfering/deburring tool is likewise provided with mobility along the conventional axes, including at least a radial infeed axis as well as a vertical movement axis.

(12) Arranged below the operating space 20 of the gear-cutting machine 100 extending between the hob 7 and the chamfering/deburring tool 8 is a portion 30 of a machine bed of the gear-cutting machine 100 in which a first workpiece spindle 1 is arranged on the side of the hob 7 and a second workpiece spindle 2 is arranged on the side of the chamfering/deburring tool 8. The workpiece spindles 1 and 2, whose respective spindle axes C1 and C2 are fixed in their positions relative to the machine bed portion 30, can be put into rotation for example by direct drives, preferably under CNC control, with one direct drive for each spindle.

(13) The first workpiece spindle 1 with the hob 7 thus constitutes a first operating station, and the second workpiece spindle 2 with the chamfering/deburring tool 8 constitutes a second operating station of the gear-cutting machine 100. At the first operating station, a hobbing operation is performed to generate a gear profile on a workpiece 5 which in the illustration of FIG. 1 is held by a first clamping device 3 which is rotationally locked to the spindle 1 during the machining engagement between the hob 7 and the workpiece 5. At the second operating station, FIG. 1 shows a second workpiece 6 being brought into machining engagement with the chamfering/deburring tool 8. For this operation, the second workpiece 6 is held by a second clamping device 4 which during the machining engagement is rotationally locked to the spindle 2. Within the operating space 20, a hobbing operation can thus be performed on the workpiece 5 while a chamfering- and deburring operation is being performed in parallel at the same time on the second workpiece 6 which has already been through the generating operation. One or both of the clamping devices 3, 4 may include at least one mark 10 by which the rotary position of the clamping device in relation to the workpiece spindle can be registered by a sensor.

(14) After a workpiece has completed the machining process, it is preferably removed from the operating space 20 while it is at the second operating station, for example by means of a tool-changer device (known in the art and not shown in the drawing) which grips the workpiece after its hold in the clamping device has been released, and the removed workpiece is replaced by a new workpiece that has yet to be machined.

(15) To move the first workpiece 5 from the first operating position into the second operating position after generating its gear profile, the first workpiece 5 is brought to the second operating position by means of a carrier 9 while remaining clamped to the first clamping device 3. However, in contrast to the state of the art, the first workpiece spindle 1 is not taken along by the carrier 9 in this position change of the workpiece 5. Rather, the first workpiece spindle 1 remains in the portion 30 of the machine bed.

(16) To perform this function, the carrier 9 is movable in its axial direction parallel to the workpiece spindle axes by means of a lifting and turning shaft 11, as indicated by the double arrow in FIG. 1. In addition, it can perform a rotary movement about the axis S. The drive mechanisms required for these two movements are not shown in FIG. 1, but they could be accommodated in the supporting structure 13 which is arranged on the gear-cutting machine 100 in a fixed position relative to the machine bed portion 30 and into which the lifting and turning shaft 11 can be retracted.

(17) To switch the place of the first work piece 5 with the second workpiece 6 or with a workpiece blank instead of the second workpiece 6 fastened in the clamping device, the first step is an upward displacement of the carrier 9 in order to vertically separate the first clamping device 3 from the first workpiece spindle 1 as well as the second clamping device 4 from the second workpiece spindle 2 after their connections have been released, for example by loosening the HSK-fittings of clamping collets installed in the workpiece spindles, wherein the clamping devices in their connected state are pulled into a cone or against a flat counter surface of the HSK-fitting. The upward displacement of the carrier 9 is at least large enough that a subsequent swivel movement of the clamping devices 3, 4 by way of a rotation of the carrier 9 about the axis S can take place without a collision between the clamping devices and the spindle shafts, as will be more clearly evident from the sectional views of FIGS. 2 and 3. After a swivel movement of the carrier 9 by 180, the carrier 9 is lowered again, the second clamping device 4 is connected to the first workpiece spindle 1 and the first clamping device 3 is connected to the second workpiece spindle 2. Now the first workpiece 5 in the second operating position can be brought into operating engagement with the chamfering/deburring tool 8, while the workpiece held by the second clamping device 4 can be machined with the hob 7.

(18) In this embodiment with two workpiece spindles and a hobbing station as well as a chamfering and deburring station, a procedural order is conceivable where each workpiece passes through the first operating station only once, according to the sequence of steps: clamping the workpiece at the second operating positions, moving the workpiece to the first operating position, hobbing the workpiece in the first operating position, moving the workpiece to the second operating position, chamfering and deburring the workpiece at the second operating position, and removing the workpiece from the operating space 20. However, it is also possible to add a step where, before leaving the operating space 20, the workpieces are returned to the first operating station, where the hob 7 performs another hobbing pass with the same or a deeper infeed position to remove secondary burrs that may have been caused by the chamfering of the tooth flanks. In this latter case, the clamping device that holds the workpiece is disconnected from one and reconnected to the other of the workpiece spindles a total of four times.

(19) FIG. 2, in a sectional plane containing the rotary axis S and the workpiece spindle axes C1, C2, illustrates an operating position that is assumed by the clamping devices 3, 4 and the carrier 9 in the machining of the workpieces 5, 6 with the tools 7, 8. In contrast, FIG. 3 shows the carrier 9 in a raised operating position, where the connections between the clamping devices and the workpiece spindles have been released, and the switching of places between the workpieces that remain fixed to their respective clamping devices can be or has already been performed by turning the carrier 9, so that a downward movement of the carrier 9 in the rotary position shown in FIG. 3 has the result that the first clamping device 3 is connected to the second workpiece spindle 2, while the second clamping device 4 is connected to the first workpiece spindle 1.

(20) FIG. 4 shows a sectional view along the line A-A of FIG. 2, which illustrates the connection between the second clamping device 4 and the second workpiece spindle 2 in an enlarged representation. As can be seen here, the end of the second workpiece spindle 2 next to the clamping device has a frusto-conical internal surface coaxial to its axis of rotation, with a widening conical taper in the direction towards the clamping device. The end of the clamping device 4 facing away from the workpiece-clamping area has a frusto-conical external surface 44 complementary to the internal surface 24. In the situation illustrated in FIG. 4, the external surface 44 and the internal surface 24 form a precise fit. The angular position of the mutually fitted surfaces relative to each other can be secured for example by a coupling engagement between rotationally asymmetric surface segments of the clamping device along the circumference of the latter and key blocks of complementary configuration which are provided for this purpose on the workpiece spindle.

(21) The clamping device 4, at the end next to the workpiece, includes a clamping cone 41 that is coaxial to the rotary axis of the clamping device 4 and serves to hold the workpiece 6. Arranged on the frusto-conical outside surface of the clamping cone 41 is an expansion sleeve 42 whose inside surface is of complementary configuration to the outside surface of the clamping cone 41. With this arrangement, the expansion sleeve 42 can be shifted between a radially contracted and a radially expanded condition by changing the axial position of the expansion sleeve on the clamping cone. Obviously, instead of the clamping cone 41, there are also other means known in the art which could be used to vary the radius of the expansion sleeve.

(22) In the operating position that is illustrated in FIG. 2, the workpiece spindle 2 with the clamping device 4, maintaining clearance and freedom of rotary movement relative to the carrier 9, passes through an opening in the latter which is delimited by a rim portion 9a. The configuration of the rim portion 9a with a portion 9b exerting a holding force on the clamping device 4 when the latter is raised (see FIG. 4) and with a flange portion 9c forming the end and reaching over the outermost radial flange 4b of the clamping device 4 does not interfere with the rotation of the workpiece spindle during the machining process while preventing chips as well as coolingand/or lubricating agents from entering.

(23) At least one of the operating positions, in the illustrated example the position of the second workpiece spindle 2, is equipped with an actuating mechanism (not shown in the drawing) whereby the workpiece 6 can be clamped to, as well as released from, the clamping device 4 by changing the radius of the expansion sleeve.

(24) In the foregoing example, changing the location of a workpiece corresponds to a step advance of the carrier through a rotation of 180, since there are two workpiece spindles. However, arrangements with three or more workpiece spindles are likewise possible, with a corresponding number of clamping devices that are advanced in angular steps of 360/n, wherein n stands for the number of spindles. For example in the embodiment illustrated in FIG. 1, a third workpiece spindle could be added for the loading and unloading at a third location, i.e. to bring a workpiece into the operating space 20 and to remove it from the latter. It is for example also conceivable to design an operating space with four spindles, wherein two of the spindles perform the functions of the operating stations described in the context of FIG. 1, but are offset from each other by only 90 rather than being arranged diametrically opposite each other. Of the two additional stations, one is designed to bring a shaving tool into operating engagement with the workpiece, while the other is dedicated to the operating steps of loading and unloading. Accordingly, a workpiece can be machined in the following sequence of steps: loading-hobbing-chamfering/deburring-shaving-unloading.

(25) As is evident from the foregoing description, in order to perform the function of switching the workpiece locations, the carrier 9 only needs to have the rim portion 9a (see FIG. 3) as well as a connection from the latter to the rotary axis S in the form of a radially extending portion 9r (see FIG. 3). However, in the illustrated embodiment, the carrier 9 extends from the axis S (in a plan view from above) not only towards the rim portion 9a but in all directions, as the body of the carrier 9 is of an essentially disk-shaped configuration. The radius is large enough that the space surrounded by the internal surface 24 of the workpiece spindle 2 (and also of the workpiece spindle 1 which is of analogous configuration in regard to this internal surface) remains covered during a rotation of the carrier 9. Thus, no chips can enter into this space during the position switch of the workpieces with the clamping devices. In the illustrated embodiment, the carrier 9 further includes a vertical separating wall 9s which stops flying chips during the machining process (se FIG. 1).

(26) FIG. 5 illustrates a further embodiment of the invention, wherein three workpiece spindles are supported on a base 60, individually rotatable for example by means of direct-acting drive sources. Analogous to the carrier 9 of FIG. 1, the carrier 59 in FIG. 5 performs an upward movement relative to the base 60 and thereby separates the clamping devices 53, 54 and 55 from the three workpiece spindles before the movement to the next position. However, in contrast to the embodiment of FIG. 1, the lifting device provided for this purpose as well as the rotary drive mechanism for the stepping movement of the carrier 59 are arranged below, rather than above, the carrier 59, i.e. in the base 60.

(27) In addition, the clamping devices 53, 54 and 55 (see FIG. 8) are also suitable for the clamping of workpieces in the shape of rotary shafts. The basic principle of advancing the workpiece in steps is still the same, in that the workpieces remain connected to the clamping devices 53, 54 and 55 as they advance to the next position, without taking the workpiece spindles along. In the snapshot shown in FIG. 5, the clamping device 53 can be seen in the machining position where the hob is operating, while the clamping device 54 is at the operating station with the chamfering/deburring tool 8, and the clamping device 55 is at a position where the workpieces can be exchanged, i.e. where a completed workpiece is taken out of the operating space of the machine and replaced by a new, not yet machined workpiece.

(28) FIG. 6 illustrates a further embodiment in which a hobbing machine is configured as a horizontal hobbing machine. Accordingly, the workpiece spindle axes are oriented horizontally. The movement of the carrier 59 relative to the machine portion 70 that holds the spindles is likewise directed horizontally, as is the rotary axis for the step-advance movement of the carrier 59.

(29) Opposite the machine portion 70 is a tailstock arrangement containing as many tailstock centers as there are workpiece spindles, as is normally the case in the machining of workpieces in the shape of rotary shafts.

(30) In the embodiment shown in FIG. 7, on the other hand, a tailstock arrangement 40 is connected to the carrier 59 in a rotationally fixed position relative to the latter. The tailstock arrangement 40 has a tailstock column 41 extending in the direction of the rotary axis of the carrier 59. The tailstock column 41 can for example have a polygonal cross-section corresponding to the number of workpiece spindles being used. In the embodiment of FIG. 7 with three workpiece spindles and three clamping devices 53, 54, 55, the cross-section of the tailstock column 41 is essentially triangular. Cantilever brackets 42a, 42b, 42c projecting radially outward from the lateral surfaces carry the tailstock centers 43a, 43b, 43c which are positioned opposite the clamping devices 53, 54, 55 to which they are permanently assigned.

(31) As indicated in FIG. 8 by the double arrow, the cantilever brackets 42a, 42b, 42c are arranged with the ability to move independently of each other relative to the tailstock column in the axial direction of the workpiece spindles. In spite of the rigid connection between the tailstock column 41 and the rotary carrier 59, this arrangement makes it possible for example to exchange the workpiece connected to the clamping device 56 in FIG. 7 by raising the tailstock center 43c and to simultaneously machine the workpieces held by the clamping device 53 (tool not shown in the drawing) and the clamping device 54 with a tool 68, for example a grinding worm for the finishing of workpieces that have been rough-machined at the preceding operating position.

(32) During the movement from one position to the next, the tailstock centers 43a, 43b, 43c are pressed against their respective workpieces, for example by means of a spring force. However, this spring-biased engagement is needed only for the time interval in which the clamping devices 53, 54, 55 are separated from their workpiece spindles. During the machining, this function is inactive, and the tailstock centers are again solidly coupled to the respective cantilever brackets 42a, 42b and 42c.

(33) Consistent with normal practice, the means for securing the rotational position of the workpieces are arranged on the side of the spindles, while the tailstock centers are only securing the axial position.

(34) While FIG. 7 symbolically indicates a grinding worm 68 as the tool of the second operating station, the illustrated tailstock arrangement 40 can of course also be used for other gear-machining processes including for example the previously described sequence of hobbing-chamfering/deburring-workpiece exchange in the case of three spindles. However, the tailstock arrangement 40 can also be used for layouts with two or with more than three clamping devices with the corresponding number of tailstock centers 43 and an appropriate coupling arrangement.

(35) Furthermore, the tailstock arrangement illustrated in FIG. 7 can also be used in machines where the workpiece spindles are not oriented vertically, for example with a horizontal arrangement of the workpiece spindles.

(36) The carrier 59 which is shown in FIGS. 5 and 7 with vertically oriented spindle axes is again configured as a disk which covers up the connector areas of the workpiece spindles that are arranged in the base 60, so that the connector areas are protected from chips and other impurities.

(37) In FIGS. 5 to 7, the arrows symbolizing the rotation of the carrier 59 indicate that the stepping movements of the carrier 59 in these examples always occur in the same rotary direction. However, for special machining sequences, in particular if a workpiece is machined twice by the same tool with an interruption in between, it is also conceivable to reverse the rotary direction and to provide the requisite control capabilities.

(38) As has been described hereinabove, during the stepping movement the clamping devices 53, 54, 55 maintain their rotary positions in relation to the carrier 59, and since the workpieces remain clamped, the position of the tooth gaps of the workpieces is traceable from one operation to the next and therefore does not have to be determined anew.

(39) This traceability is maintained not only during the rotation of the carrier 59 but also in the case of a possible power failure. Depending on the desired control action, the stationary workpiece spindles can be held in their positions while they are uncoupled from the clamping devices, or they can also be turned so that a given azimuthal reference of any of the workpiece spindles always takes on the same rotary position relative to a given azimuthal reference of a clamping device.

(40) The invention is not limited to the details described hereinabove in the context of the individual examples of constructively realized embodiments. Rather, the features set forth in the following claims as well as in the description, used individually or in combination, can be essential for the practice of the invention in its different embodiments.