Method for hard finishing two teeth of a workpiece, tooth cutting machine, control program, hard finishing combination tool, and sensor configuration therefor

Abstract

1. A method for hard finishing two different toothings of a workpiece, wherein before each machining process, a first relative rotational angular position of a first rotational position reference of a first toothing is determined relative to an axial rotational position of a workpiece spindle that holds and clamps the workpiece for the first machining, and a second relative rotational angular position of a second rotational position reference of a second toothing is determined relative to an axial rotational position of a workpiece spindle that holds and clamps the workpiece for the second machining, in order to set the correct tool engagement position for the machining process, and the machining operations are performed on the same workpiece spindle with the first and second rotational position references coupled to each other as their basis, without any intervening clamping changes.

Description

[Technical Field]

[0001] The present invention relates to a method for hard finishing two different toothings of a workpiece, wherein before each machining process a first relative angular position of a first rotational position datum of a first toothing is determined relative to an axial rotational position of a workpiece spindle that holds and clamps the workpiece for the first machining, and a second relative angular position of a second rotational position datum of a second toothing is determined relative to an axial rotational position of a workpiece spindle that holds and clamps the workpiece for the second machining, in order to set the correct tool engagement position for the machining process.

[0002] Such methods are known, for example, for shaft-shaped workpieces with two or more toothed sections. However, there are also "dumbbell-shaped" workpieces in which two working gears, possibly of different diameters, are connected to each other, possibly by a very short shaft. In such workpieces, the gear body of one of the toothed sections forms the shoulder of the other toothed section, and therefore the latter cannot be machined in the production process, which would otherwise be the most accurate and economical method. Such teeth are hard-finished, for example, by a process in which the larger (larger diameter) toothed section is hard-finished by production grinding, while the smaller toothed section is hard-finished using an internal honing ring.

[0003] A suitable rotational position of the tool and workpiece is required for each machining operation. The rotational position is typically set once for the first workpiece to be machined in a workpiece batch. For example, the tool tooth is inserted into the tooth gap of the workpiece toothing (first centering), first contacting the left tooth flank of the workpiece by tangential displacement or relative rotation, then contacting the right tooth flank. The rotational position of the contact situation is recorded, and the center of the tooth gap of the workpiece toothing is calculated, for example, by averaging the rotational position reference or the relative rotational angle position of this rotational position reference with respect to a pre-specified axial rotational position of the workpiece spindle. This can also occur in a continuous process. This is the procedure in known techniques, for example, for the generation grinding of the first toothing. For subsequent toothings of the same workpiece batch, this initialization operation is no longer necessary to set the proper engagement; it is sufficient to bring the subsequent workpiece into the same rotational position as the first machined workpiece. For this purpose, it is sufficient to bring the position of the tooth gap center (first rotational position reference) into a specified axial rotational position of the workpiece spindle (workpiece spindle reference). The positions of the tooth gap and the tooth gap center themselves can be determined, for example, by means of contactless inductive sensors.

[0004] For the second tooth to be honed, for example, the workpiece is unclamped from the workpiece spindle of the grinding machine and clamped to the workpiece spindle of the honing machine, and the tool engagement setup (initial centering) is performed for this tooth. In addition, a subsequent workpiece centering operation is performed by determining the tooth gap center (second rotational position reference) relative to the workpiece spindle reference of the honing machine.

[0005] All known methods for machining workpieces having multiple different toothings have advantages and disadvantages.

[0006] The present invention is based on the object of further improving such methods, especially with regard to high accuracy requirements.

[0007] This object is achieved according to the invention by a further development of the method of the type mentioned at the outset, which is essentially characterized in that the machining is carried out on the same workpiece spindle without any intervening clamping change, with the first and second rotational position references coupled to each other as their basis, and the machining mode of the hard finishing process of the first and second toothings is in particular the same, preferably that of a helical gear mechanism in terms of machining engagement, and the rotation axes of the two toothings are matched and coincide with the workpiece spindle axis.

[0008] In a further development of the present invention, clamping is maintained, so that the relative rotational position of the workpiece with respect to the workpiece spindle reference, the rotational position of which has been determined and recognized once, is preserved. Centering operations for each individual toothing are necessary anyway, and the specific tooth gap of the workpiece toothing at which the machining process begins is usually not important, since it is not relevant for certain machining operations using hard finishing tools. However, the further inventive concept of the underlying coupled first and second rotational position references breaks the relevant symmetry insofar as the relative rotational position of the first toothing relative to the second toothing is important. For example, if an arbitrary tooth gap of the first toothing is selected, the nearest tooth gap of the other toothing, for example in the clockwise direction, is a pre-specified rotational angle distance from this tooth gap of the first toothing (measured relative to the respective tooth gap centers). In this regard, it is preferable that the coupling consists of a rotational angle difference between the first and second rotational position references that is within the tolerance of the pre-specified rotation angle.

[0009] Since the first and second toothings differ from one another, particularly in terms of module, helix angle, tooth width, and / or toothing diameter, such a rotational angle difference depends on which two tooth gaps, e.g., adjacent, are selected in the projection plane of the workpiece axis (or at a specified distance from one another). For this purpose, the first and second rotational position references are preferably assigned to a prespecified reference, particularly a selected reference tooth of the toothing. In certain embodiments, for example, a reference tooth from the first or second toothing is selected, and the tooth gap adjacent to this tooth in the clockwise direction, i.e., its tooth gap center, is selected as the rotational position reference. Again, the closest tooth gap (tooth gap center) of the other toothing, as viewed in projection onto the normal plane of the workpiece rotation axis, is selected. It goes without saying that tooth centers or hybrid combinations thereof can be used instead of tooth gap centers. Furthermore, it goes without saying that the assignment to the reference tooth can be designed using other teeth or tooth gaps that can be determined in a specified, traceable manner using the reference tooth. For example, the first rotational position reference may also be the seventh tooth clockwise from the reference tooth, and the second rotational position reference may be the third tooth gap of the other tooth section counterclockwise relative to the reference tooth.

[0010] The axial rotational position of the workpiece spindle, indicated by a zero crossing during rotation of the workpiece spindle (as an example, and typically detected by a rotary encoder on the workpiece spindle), can in principle be freely selected; only the relative rotational angle position with respect to the rotational position reference on the respective workpiece tooth is important. To implement the reference and maintain the desired rotational angle by taking the rotational angle difference between the first and second rotational position references, the absolute position of the workpiece spindle reference is not important due to the fact that the difference is taken, but only its existence is important. This means that the control device of the machine performing the method knows the rotational position to which the workpiece will be moved for the machining operation and that the reference, e.g., the selected reference tooth, is located at this rotational position.

[0011] In a particularly preferred embodiment of the method, this reference, and therefore in particular the predetermined selection of the reference tooth, is determined by markings, in particular arranged on the workpiece itself. In the simplest possible case, a marking that can be detected by a sensor, i.e. in the case of an optical sensor, can be any letter, inscription, etc., or even, for example, a simple hole in the wheel body of the other, larger toothing, approximately at the tooth center with respect to the rotation angle of the toothing. The latter is considered particularly advantageous, since it can be detected by a non-contact sensor in a manner similar to a central sensor.

[0012] As already explained at the beginning, the method according to the invention also preferably defines the rotational position of the first workpiece for machining engagement using a given tool and records the rotational position references of the first and second toothings in their positions relative to the workpiece spindle reference, in particular for the rotational position reference defined by the reference determination explained above. This feature as claimed in claim 5 can be implemented again when the tool is changed or re-profiled.

[0013] Therefore, this configuration is no longer necessary for subsequent workpieces in the same workpiece batch; rather, the appropriate axial rotation position for tool engagement can be provided using the first or second relative rotation angle position determined for that workpiece, particularly by the non-contact sensor.

[0014] In this context, even if a specified reference, in particular a selected reference tooth, is identified for each workpiece, it is preferred that for this purpose the rotational position of the marking, in particular, is detected by a sensor, in particular in a contactless manner. In this way, the controller not only knows where the tooth gap is for the first and second toothings, but also where, for example, a specific tooth gap of the first and second toothings is located, which serves as a reference for specifying the rotation angle difference between the two rotational position references that must be observed.

[0015] In a particularly preferred embodiment, the second rotational position reference / second relative rotational angular position is determined before machining of the first toothing begins, and vice versa. Identification of the reference and / or reference tooth is also preferably performed before machining of one of the toothings begins. This means that the machine controller has information it can use to set the appropriate rotational position for machining engagement. This is because a tolerance range exists for each individual machining operation, within which the controller can select the final rotational position of the workpiece spindle for the machining operation.

[0016] Usually, the control algorithm aims to position itself exactly in the middle of the tolerance so that the removal of the left and right flanks in particular is symmetrized and even tool wear is achieved as a result. However, in a preferred embodiment of the method, a constraint is coupled to the procedure so that the rotation angle difference between the first and second rotational position references matches a specification within the tolerance, and this constraint is taken into account to determine the rotational positions of the individual machining processes in the individual tolerance ranges, preferably based on the symmetrization of the positions within the tolerance ranges for both machining operations.

[0017] As a simplified example, both individual tolerance ranges (on the pitch circle) have tolerances between +5 μm and -5 μm (these values ​​are merely illustrative). In an ideal case, the correct rotation angle difference would also be set to 0 μm. However, if a value of +2 μm is selected for one toothing while maintaining 0 μm due to deformation resulting from hardening, the control is symmetrical for the other toothing, and -1 μm is selected instead of 0 μm and +1 μm instead of +2 μm, while still respecting the constraints. In this way, even for tolerances sensitive to rotation angle differences of just a few minutes of arc, for example, ±5 arc minutes or less, preferably ±2 arc minutes or less, and more preferably ±1 arc minute or less, it is possible to achieve ±40 arc seconds or less, particularly ±25 arc seconds or less, or even ±15 arc seconds or less. Before mutual adjustment is no longer possible due to the machining of one toothing that would otherwise have been completed, both tolerance ranges for the individual machining processes can be used, and the combination can be seen to minimize the amount of defects that no longer meet this criterion.

[0018] In a preferred embodiment, the hard finishing tool can be resharpened / dressed, and a dressing tool, particularly a diamond dressing wheel, is provided for this purpose, particularly in the form of a toothing, arranged on the same workpiece spindle as the first and second toothings, due to their fixed relative rotational position coupling. Due to the rotational position coupling of the dressing tool, the relative position of the teeth is retained, even after dressing, for example, with two internal honing rings. Instead of the diamond dressing wheel, a thin-tooth dressing wheel can also be used, the engagement of which is controlled by an additional axial machine movement.

[0019] With regard to the apparatus, the present invention includes a tooth cutting machine for hard finishing such workpieces within a protected area, having the necessary workpiece holder and tool holder, rotation and positioning axes, and a control device with control instructions for carrying out the method according to one of the above aspects.

[0020] Such a tooth cutting machine preferably has two, in particular three, sensors, one for determining the tooth gap of each toothing and a third sensor, in particular for detecting the position of the marking. Such a sensor arrangement with three sensors is also included independently within the scope of protection.

[0021] Additionally, the tooth cutting machine can also be equipped with a resharpening or profiling device for hard finishing tools.

[0022] The invention also provides a hard finishing combination tool suitable for carrying out such a method, in a first example having geometrically undefined cutting edges, preferably in the form of two bonded internal honing rings, and in another embodiment a tool having geometrically defined cutting edges, in particular in the form of an external skiving wheel.

[0023] The method of the above aspect allows for hard finishing of workpieces having angularly synchronous stepped teeth, particularly for planetary gear applications, for example in electronic drive transmissions, to a satisfactory level of accuracy. [Brief explanation of the drawings]

[0024] Further features, details and advantages of the present invention can be found in the following description which refers to the accompanying drawings.

[0025] [Figure 1] FIG. 1 is a perspective view of a workpiece having two teeth. [Figure 2] 1 is a schematic diagram of a rotational position reference in a projection plane with a workpiece axis perpendicular thereto. [Figure 3] The structure of a honing machine with two internal honing rings is shown. [Figure 4] FIG. 1 is a schematic diagram showing the honing ring and workpiece teeth as well as the sensor and dressing tool. [Figure 5] This shows a skiving machine. [Figure 6] 1 shows a hard finishing tool with two hard skiving wheels. DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 1 shows a workpiece 4 in a perspective view. The workpiece 4 is rough-finished with two teeth: a larger (larger diameter) toothing 1 and a smaller (smaller diameter) toothing 2, which are connected to each other via a shaft and have coaxial rotation axes. The two teeth also form the two axial ends of the workpiece 4. For the hard-finishing process, the workpiece 4 is clamped to a workpiece spindle, the workpiece spindle axis of which is coaxial with the rotation axis of the teething. Teething 1 can be produced, for example, by hobbing, and teething 2 by forming or skiving, although other combinations could also be used. The present invention begins with the hard-finishing process.

[0027] This means that toothings 1 and 2 still have the machining tolerances that remained when toothings 1, 2 were created, in terms of the final tooth flank geometry, and hardening may also result in hardening deformations and therefore in a slightly changed tooth shape. In hard finishing, the remaining machining tolerances must be removed together with the hardening deformations to give toothings 1, 2 their final geometry.

[0028] Also visible in Figure 1 is a hole 3 formed in the wheel body of toothing section 1. As can be seen better in Figure 2, hole 3 serves as a marker for identifying tooth 21 of toothing section 2, i.e., tooth 21 at a rotational position that substantially corresponds to the rotational position of marking 3, for example. The exact correspondence is not critical. An angular offset can be provided, and the tooth of toothing section 2 that is adjacent thereto in the counterclockwise or clockwise direction can be marked as the tooth 21 identified by marking 3. Marking 3 can also be used to mark a tooth gap 22, or a tooth, for example tooth 12 of toothing section 1, or a tooth gap of the larger toothing section 1.

[0029] Relative to the marking 3, there exists a rotation angle φ2 between the tooth center of the tooth 21 of the toothing 2 and the tooth gap center of the adjacent tooth gap 22. The rotation angle φ2 is determined based on the module of the toothing 2. However, if the markings are located at different positions, the angle value may not be known in advance. An angle φ1 exists between the rotation position determined by the marking 3 (and / or its center) and the next tooth gap 12 of the toothing 1 in the clockwise direction. The relative rotation position of the toothing 1 with respect to the toothing 2 is determined relative to the reference determined by the marking 3 by the rotation angle difference Δφ=φ2-φ1 between the two tooth gap centers 22 and 12. This angle difference Δφ should correspond to a pre-specified angle difference Δφ0 with respect to the workpiece 4 within a very small tolerance ±δΔφ of only 5 arc minutes or less, preferably 1 arc minute or less, and in particular 25 arc seconds or less.

[0030] In the following, it is assumed that not only are workpieces 4 of the type shown in Figure 1 subjected to hard finishing, but that there is also a larger workpiece batch of these workpieces 4. This batch has undergone the same manufacturing process with regard to the creation of the teeth 1, 2 and the hardening process, but the hardening process may have a slightly different machining tolerance distribution due to the manufacturing process and may have a different hardening deformation.

[0031] For hard finishing, workpiece 4 of the workpiece batch is clamped on a workpiece spindle (having a workpiece spindle rotation axis C2 in the embodiment of FIG. 3 ), and hard finishing of toothing 1 and toothing 2 is performed without any intervening clamping changes, i.e., on the same workpiece spindle and with the same clamping. Furthermore, hard finishing of toothing 1 and toothing 2 is performed using the same hard finishing method: gear honing (shaving) with an internal honing ring in the embodiment of FIG. 3 , or hard skiving with an external hard skiving wheel in embodiment 2 ( FIG. 5 ). Therefore, hard finishing is preferably performed in the machining engagement of a helical gear unit, in which the rotation axis of the machined toothing and the rotation axis of the machining tool are at an intersecting axis angle. For the tool, the relative rotational positions of two different gear cutting tools (due to the different toothings 1 and 2) must also be rotationally fixedly coupled to each other, which is sometimes referred to as a tandem tool. Therefore, the workpiece spindle reference is the designated axial position of the C2 axis.

[0032] The following description is based on the embodiment according to FIGS. 3 and 4, in which the toothings 1 and 2 are honed by means of two internal honing rings 101 , 102 firmly fixed in a honing head 104 .

[0033] A more detailed description of the tooth honing machine 100 shown in FIG. 3 will be omitted, as such designs are already well known to those skilled in the art. It goes without saying that a gear honing machine has a machine bed 180 and the necessary carriage and machine axes to perform gear honing using an internal honing ring. In the embodiment shown in FIG. 3, the rotation axis C1 of the honing rings 101 and 102 can be set at an intersecting axis angle with the workpiece spindle axis C2, which is fixed in axial position, by a pivot axis A1. The machine also has an additional pivot angle B1, which is linearly independent of the pivot axis A1 and preferably perpendicular to the axial direction of the pivot axis A1 and the workpiece axis C2. This, in turn, is parallel to the linear movement axis Z2 of the workpiece spindle. The honing head 104 is mounted on compound slides 161, 162 on the tool, which are displaceable parallel to the workpiece axis (Z1 axis) and radially (through linear axis X1) relative to the workpiece axis Z2. To take into account machining that is eccentric to the axis intersection, the B1 axis, which can typically be used to correct or influence tooth marks, can in this case be used as a further axis of motion. Alternatively, an additional linear axis Y1 may be provided, for example, perpendicular to X1 and Z1.

[0034] The workpiece rotation axis C2 conventionally has a drive and a rotary encoder, by which the rotational position of the workpiece spindle (rotation axis reference) relative to a pre-specified reference position, such as the internal zero crossing of the workpiece spindle, is known. The tool spindle C1 also has such a rotary encoder.

[0035] When a new workpiece is clamped onto the workpiece spindle for hard finishing, the position of the tooth gap of, for example, toothing 2 relative to the workpiece spindle reference is usually unknown after clamping. Preferably by means of a non-contact sensor (index sensor), e.g., an inductive sensor, the position of the tooth gap relative to the workpiece spindle reference can be determined by passing the sensor 120 over toothing 2 a few tooth gaps. If the mutual angular position of the workpiece spindle axis and the tool rotation axis is first determined by the initial configuration of the machining engagement between the honing ring 102 and toothing 2 (e.g., a conventional initial centering operation by lowering the tool into the tooth gap, rotating it to contact the tooth flanks on the left and right sides of the gap while holding the rotational position at contact, and calculating the tooth gap center by averaging), the machine controller 99 of the tooth cutting machine 100 knows the rotational position to which the workpiece spindle must be moved relative to its own reference in order to be in the correct rotational position for the machining operation. These methods are already well known per se for individual teeth and can be carried out for toothing 1 (and its machining engagement with honing ring 101) as well.

[0036] However, when machining individual gears of this type, it usually doesn't matter which tooth gap is moved to the machining position. However, in this case, the relative rotational position of toothing 1 with respect to toothing 2, represented by the rotational angle difference Δφ, must be maintained within very strict tolerances using the reference provided by marking 3. To this end, a third sensor, e.g., a non-contact inductive sensor, is also provided in this embodiment to detect the rotational position of marking 3 and form the basis of the reference for the rotational angle difference Δφ. In these configurations, three non-contact sensors 120, 130, and 110 are provided to determine the rotational positions of the tooth gap of toothing 2, marking 3, and the tooth gap of toothing 1. The sensors 110, 120, and 130 can be fixed in place via a common support arm 150 (as shown) or movable via sliding / movable arms and / or a combination thereof. The support arm 150 may be retractable.

[0037] Since the honing rings 101 and 102 cannot rotate relative to one another, and toothing 1 cannot rotate relative to toothing 2, all information is available for the machining operation on toothing 1 by honing wheel 1 to enable it to work within the individual tolerances specified for the individual machining process, i.e., to start from the rotational position of the tooth gap center relative to the workpiece spindle reference, compared to that of the master wheel from the initial setting, for the machining rotational position within the individual tolerances relative to the "master wheel," and in this way to ensure that there is in any case a sufficiently removable tolerance relative to the final tooth flank geometry (thus, movements are made starting from the manufacturing tolerances of toothing 1 itself). The same must be done for toothing 2, and both configurations should preferably be pre-adjusted to one another so that the rotational position difference Δφ is within the specified tolerance δΔφ.

[0038] The effect will be discussed below using a greatly simplified example for illustrative purposes. It goes without saying that the setting for the "master wheel," i.e., the first workpiece to be machined in a workpiece batch and / or the first workpiece in a resumed process, is configured after re-profiling the honing rings 101, 102 to the appropriate rotational engagement position while maintaining the angular difference Δφ. If we make an exaggerated assumption that hardening of toothing 2 has caused deformations that tend to shift the tooth gap center clockwise and toothing 1 counterclockwise, the controller compares the relative rotational position of the first rotational position reference for toothing 1 with the reference of the workpiece spindle relative to that of the master wheel to determine the appropriate rotational position setting for machining relative to that of the master wheel, and ideally corrects by moving toothing 1 by, for example, -|δφ1| to the center of the tolerance range, and by moving toothing 2 by +|δφ2| in the same approach. However, for this workpiece, the rotational angle of toothing 2 relative to toothing 1 has a difference Δφ. *If there exists a relationship between |δφ2|+|δφ2|-(φ1-|δφ1|)=Δφ+(|δφ1|+|δφ2|) and |δφ2|+|δφ1|>δΔφ, then this is a workpiece that no longer meets the requirements.

[0039] By combining the rotational position references of tooth 1 and tooth 2 (with reference to the constellation identified by marking 3 or otherwise), Δφ * In addition to always being within the tolerance of Δφ0 (if this is still theoretically possible), it is ensured that the respective individual tolerances are still observed, but the optimum center of the tolerance range of the individual tolerances of the individual toothings 1, 2 is no longer observed in the individual machining processes of the toothings 1, 2.

[0040] In conventional provision of such a workpiece 4, where one toothing is machined by grinding and after changing the clamping the other toothing is machined, for example by honing, or the reverse order is used, hard finishing has already been performed and, ignoring clamping of the same workpiece in which this has not been performed, there is no longer any margin of error in terms of tolerance that can be used to ensure that the rotational position difference Δφ is within tolerance.

[0041] 4 again shows the honing wheels 101 and 102 rotationally coupled within the honing head 104, and the sensors 110, 120, and 130. A tailstock center 109 and diamond dressing wheels 401, 402 are also provided on the workpiece spindle 108 for dressing the honing rings 101, 102.

[0042] It goes without saying that the type of marking 3 as a hole in the disk body of toothing 1 and sensor-based detection of its rotational position is only one of several options for determining the criterion for applying the specified rotational angle difference Δφ (if the rotational angle difference between two tooth gaps of adjacent toothings 1 and 2 at any other point in the projection plane is taken into account, in principle this would be significantly different from Δφ0 due to the different toothings, and therefore the criterion determination itself would be preferable).

[0043] For example, it is conceivable that the detection of the rotational position of the tooth gap of toothing section 1 with reference to the workpiece spindle and the detection of the rotational position of the tooth gap of toothing section 2 with reference to the workpiece spindle described above can be used to identify a characteristic pairing of two teeth or tooth gaps of toothing section 1 and toothing section 2 that occurs only once, and that this characteristic pairing determines the angular position difference Δφ' and introduces it as a constraint for setting the rotational position for the respective machining operation.

[0044] A second embodiment is shown in Figures 5 and 6. The hard skiving machine 200 shown in Figure 5 has a machine bed 280, on one side of which is arranged a workpiece table with a workpiece spindle 270. The latter can be equipped with an adapter clamp (not shown) for receiving the workpiece 4 shown in Figure 1. The tailstock arrangement of the opposite attachment point is not shown (similar to the tailstock center 109 in Figure 4).

[0045] On the tool, a main stand 261 is provided that can move along the radial direction X, on which a vertical carriage 262 can move in the Z direction parallel to the workpiece axis. It carries a tangential carriage 263 that can rotate with the rotation axis A (Y direction in the rotation position A shown) to set the cross-axis angle. A hard skiving head is mounted on the tangential carriage 263. In FIG. 5, the machine is shown with just one single tool with a hard skiving wheel, but preferably a tandem tool is used, as shown in FIG. 6. The machine 200 and its axial movements are controlled by a controller 299.

[0046] In this case, hard finishing is performed on a hard skiving machine having a combined tool configuration roughly shown in FIG. 6 , consisting of two hard skiving wheels 201 and 202 for hard skiving teeth 1 and 2. The approach for determining the rotational position is as described with reference to the first embodiment, but the type of hard finishing changes due to the machining with geometrically defined cutting edges. Again, the two hard skiving wheels 201 and 202 are rotationally coupled, so the relative rotational position setting of the two hard skiving wheels, which is the same on the tool, applies to all workpieces 4 of the batch. Again, although not shown, three sensors are preferably provided for detecting the first and second rotational position datums and the rotational position of the datum (marking 3), e.g., attached to the tool head via a support structure.

[0047] However, it is also possible to use internal skiving rings, i.e. tools with geometrically defined cutting edges similar in shape to the honing rings 101, 102. Tooth honing using externally toothed wheels similar in form to the hard skiving wheels 201, 202, but with geometrically undefined cutting edges, is also conceivable.

[0048] As will be appreciated, the present invention is not limited to the details set forth in the above embodiments, but rather individual features of the following claims, as well as of the above description and the following claims, may be essential both individually and in combination to implement the invention in its different embodiments.

Claims

1. A method for hard finishing two teeth of a workpiece (4), the first toothing (1) and the second toothing (2), which are arranged at different axial positions and have different diameters, the method comprising: determining, before each machining process for hard finishing the first toothing (1) and the second toothing (2), a first relative rotational angle position (φ1) of a first rotational position reference of the first toothing (1) relative to a rotational position about a rotational axis (C2) of a workpiece spindle (108) that holds and clamps the workpiece for hard finishing the first toothing (1); and determining a second relative rotational angle position (φ2) of a second rotational position reference of the second toothing relative to a rotational position about the rotational axis (C2) of a workpiece spindle (108) that holds and clamps the workpiece for hard finishing the second toothing (2), in order to set a correct tool engagement for the machining process; wherein the machining process is performed on the workpiece spindle (108) without an intervening clamping change, with the first and second rotational position references coupled to one another as a basis for the machining process.

2. 2. The method of claim 1, wherein the coupling is such that a rotation angle difference (Δφ=Φ2-Φ1) between the first rotational position reference and the second rotational position reference corresponds to a pre-specified rotation angle (Δφ0) within an allowable error (±δΔφ).

3. 3. The method according to claim 1, wherein the first and second rotational position references are assigned to pre-specified references, the pre-specified references consisting of selected reference teeth of the toothing (1) or the toothing (2).

4. 4. The method according to claim 3, wherein the pre-specified reference consisting of the reference tooth is determined by a marking (3) placed on the workpiece itself.

5. 5. The method according to claim 1, wherein for a first machined workpiece of a batch of identical workpieces and / or for a first machined workpiece after changing or resharpening / profiling at least one of the tools, the first and / or second relative rotational angular positions are determined via sensor detection of contact between the toothing of the workpiece and the tool, and an axial rotational position suitable for the tool engagement is determined therefrom.

6. 6. The method of claim 5, wherein the workpiece subsequent to the initial machined workpiece is set to the correct axial rotation position for the tool engagement based on the first and / or second relative rotational angular positions determined for that workpiece by a non-contact sensor.

7. 5. The method according to claim 4, wherein the pre-specified reference, the selected reference tooth, is also identified for each workpiece, and for this identification, the rotational position of the marking is detected in a contactless manner by a sensor.

8. 8. The method according to claim 1, wherein the determination of the second relative rotational angle position is performed before machining of the first toothing starts, or machining of the first toothing is performed before determination of the second relative rotational angle position starts.

9. 9. The method according to claim 1, wherein two dressing tools (401, 402) that are hard finishing tools (101, 102) are arranged in the shape of the toothing of the workpiece with a fixed rotational position coupling relative to each other and are arranged on the same workpiece spindle (108) as the first and second toothings (1, 2).

10. A tooth cutting machine (100; 200) for hard finishing first and second toothings (1, 2) of different diameters arranged at different axial positions on a workpiece (4), the tooth cutting machine (100; 200) comprising: at least one workpiece spindle (108) for rotating said workpiece by a workpiece spindle drive; a tool head (104; 204) for mounting a first hard finishing tool (101; 201) for hard finishing the first toothing (1) and a second hard finishing tool (102; 202) for hard finishing the second toothing, the first hard finishing tool and the second hard finishing tool being rotatable about a tool axis (C1) by a tool spindle drive; A tooth cutting machine (100; 200) comprising at least two non-contact sensors (110, 120) for detecting the tooth gap of a first tooth portion and the tooth gap of a second tooth portion, and a control device (99) having control instructions for carrying out the method according to any one of claims 1 to 9.

11. 11. The tooth cutting machine of claim 10, further comprising a third sensor (130) for detecting a marking (3) placed on the workpiece, the third sensor (130) identifying a pre-designated tooth on the workpiece that is referenced to one of the rotational position references.

12. 12. The tooth cutting machine according to claim 10 or 11, comprising two dressing tools (401, 402) for the first and second hard finishing tools, coupled in a fixed rotational position relative to each other and arranged on the workpiece spindle (108).

13. A control program having control instructions which, when executed on a control device of a tooth cutting machine, controls the tooth cutting machine to perform the method according to any one of claims 1 to 9.

Images