PROCESS FOR MACHINING A GEAR WORKPIECE, AND CORRESPONDING PAIR OF GEARS
20200332877 · 2020-10-22
Inventors
- Alexander Landvogt (Rheinstetten-Mörsch, DE)
- Rolf Schalaster (Wermelskirchen, DE)
- Hartmuth Müller (Remscheid, DE)
- Carsten Hünecke (Hessisch Oldendorf, DE)
Cpc classification
F16H2055/086
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H55/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B23F17/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
F16H57/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H1/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
The present disclosure relates to a process for machining a gear workpiece (100) comprising a plurality of tooth spaces (6), each of which is defined by two tooth flanks (5.1, 5.2); in said process, a gear tooth-forming tool (1) is used in order to provide at least one subset of all the tooth flanks (5.1, 5.2) with a non-periodically distributed modification of the flank geometry.
Claims
1. A method comprising: fine machining with a multiaxis gear cutting machine a gear wheel workpiece comprising multiple tooth flanks and multiple tooth gaps, each tooth gap defined by two of said tooth flanks, wherein said fine machining includes performing a non-periodically distributed modification of flank topography of at least a subset of said tooth flanks using a gear cutting tool, the method further including assigning an individual target topography to each tooth flank of the at least a subset, measuring actual topography of at least a plurality of tooth flanks of the at least a subset after said fine machining, comparing, using a computer, the actual topography to the individual target topography of said at least a plurality and, in turn, determining any deviations between the actual topography and the individual target topography of said at least a plurality, and when deviations exist, one or more of: performing a correction machining process on at least a portion of said at least a plurality, or when said gear wheel workpiece is of a series of gear wheel workpieces fine machined in the gear cutting machine, performing said correction machining process on respective tooth flanks of at least one other gear wheel workpiece in the series.
2. The method according to claim 1, wherein, after performing the non-periodically distributed modification of the flank topography, each tooth flank of the at least a subset has a different topography than all other tooth flanks of the subset.
3. The method according to claim 1, wherein, after performing the non-periodically distributed modification of the flank topography, no convex tooth flanks of adjacent tooth gaps of the at least a subset have the same topography.
4. The method according to claim 1, wherein, after performing the non-periodically distributed modification of the flank topography, no concave tooth flanks of adjacent tooth gaps of the at least a subset have the same topography.
5. The method according to claim 1, wherein said method defines a single-indexing method.
6. The method according to claim 1, further comprising predetermining a spatially and chronologically varied relative movement of the gear cutting tool relative to the tooth flanks of the at least a subset is using a CNC controller of the gear cutting machine so that one or more of: (i) for each convex tooth flank of the subset, said fine machining generates a different flank topography than a subsequent convex tooth flank of said subset, or (ii) for each concave tooth flank of the subset, said fine machining generates a different flank topography than a subsequent concave tooth flank of said subset.
7. The method according to claim 1, further comprising using a software program or a software module in the multiaxis gear cutting machine before the fine machining step, determining, with a computer, a tooth contact between the gear wheel workpiece and a second gear wheel workpiece to be paired therewith, and determining a non-periodically distributed modification of the tooth contact for the contact of each tooth flank of the gear wheel workpiece with a conjugated tooth flank of the second gear wheel workpiece.
8. The method according to claim 1, further comprising, before the fine machining step, determining the non-periodically distributed modification using flank generator software.
9. The method according to claim 1, further comprising, prior to determining the periodically distributed modification, determining an ease-off function configured to provide the non-periodically distributed modification of the flank topography.
10. The method according to claim 1, wherein one or more of the fine machining step or the correction machining process includes generating a flank topography of a first tooth flank of the at least a subset of the tooth flanks that differs from a flank topography of a second tooth flank of the at least a subset of the tooth flanks that is adjacent to the first tooth flank.
11. The method according to claim 1, wherein the fine machining step includes machining the at least a subset so that, when the gear wheel workpiece is paired and operated with a second gear wheel workpiece, an effective torque transmission ratio thereof has a reduced periodic excitation compared with operation of a pairing of said gear wheel workpiece and the second gear wheel workpiece on which said fine machining step has not been performed.
12. The method according to claim 1, the fine machining step includes machining the at least a subset so that, pair when the gear wheel workpiece is paired and operated with a second gear wheel workpiece, an effective torque transmission ratio thereof is substantially free of resonances.
13. The method according to claim 1, wherein one or more of the fine machining step or the correction machining process includes generating tooth flank profiles of the at least a subset configured for pairing of the gear wheel workpiece with a second gear wheel workpiece with intermeshing tooth flank profiles wherein each engagement of a tooth flank of the gear wheel workpiece with a flank of the second gear wheel workpiece differs from an engagement of a subsequent tooth flank of the gear wheel workpiece with a subsequent flank of the second gear wheel workpiece.
14. The method according to claim 1, defining a grinding method or a hard-skiving method.
15. (canceled)
16. The method according to claim 1, wherein at least a portion of the measuring step is performed with the gear wheel workpiece in the gear cutting machine.
17. The method according to claim 1, further comprising further finish machining at least one of the tooth flanks of the at least a subset in the gear cutting machine.
18. (canceled)
19. A gear wheel pair comprising a first gear wheel workpiece and a second gear wheel workpiece configured to engage with the first gear wheel workpiece, wherein the first gear wheel workpiece is made by a method comprising: fine machining with a multiaxis gear cutting machine the first gear wheel workpiece comprising multiple tooth flanks and multiple tooth gaps, each tooth gap defined by two of said tooth flanks, wherein said fine machining includes performing a non-periodically distributed modification of flank topography of at least a subset of said tooth flanks using a gear cutting tool, the method further including assigning an individual target topography to each tooth flank of the at least a subset, measuring actual topography of at least a plurality of tooth flanks of the at least a subset after said fine machining, comparing, using a computer, the actual topography to the individual target topography of said at least a plurality and, in turn, determining any deviations between the actual topography and the individual target topography of said at least a plurality, and when deviations exist, one or more of: performing a correction machining process on at least a portion of said at least a plurality, or when said first gear wheel workpiece is of a series of gear wheel workpieces fine machined in the gear cutting machine, performing said correction machining process on respective tooth flanks of at least one other gear wheel workpiece in the series.
20. The gear wheel pair according to claim 19, wherein the second gear wheel workpiece is made by a method comprising: fine machining with the multiaxis gear cutting machine the second gear wheel workpiece comprising multiple tooth flanks and multiple tooth gaps, each tooth gap defined by two of said tooth flanks, wherein said fine machining includes performing a non-periodically distributed modification of flank topography of at least a subset of said tooth flanks using a gear cutting tool, the method further including assigning an individual target topography to each tooth flank of the at least a subset, measuring actual topography of at least a plurality of tooth flanks of the at least a subset after said fine machining, comparing, using a computer, the actual topography to the individual target topography of said at least a plurality and, in turn, determining any deviations between the actual topography and the individual target topography of said at least a plurality, and when deviations exist, one or more of: performing a correction machining process on at least a portion of said at least a plurality, or when said second gear wheel workpiece is of a series of gear wheel workpieces fine machined in the gear cutting machine, performing said correction machining process on respective tooth flanks of at least one other gear wheel workpiece in the series.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Exemplary embodiments of the invention, which are understood not to be limiting, are described in greater detail hereafter with reference to the drawings.
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DETAILED DESCRIPTION
[0054] Terms are used in conjunction with the present description which are also used in relevant publications and patents. However, it is to be noted that the use of these terms is merely to serve for better comprehension. The inventive concepts and the scope of protection of the claims for protection are not to be restricted in the interpretation by the specific selection of the terms. The details presented herein may be readily transferred to other term systems and/or technical fields. The terms are to be applied accordingly in other technical fields.
[0055] The details presented herein may be applied, for example, to the single-indexing method, as mentioned at the outset. Therefore, details in this regard are described in conjunction with
[0056]
[0057]
[0058] A substep of the hard-fine machining of a gear wheel workpiece 100 can be seen in principle in
[0059] The method details presented herein is preferably used in all embodiments in a gear wheel grinding machine or in a hard-skiving machine, wherein the controller 50, or a software module, or software SW ensures the specification of the stochastically distributed additional movement. Reference is made here in general to multiaxis gear cutting machines 20, wherein CNC-controlled machines 20 are preferably used in all embodiments.
[0060] Gear cutting machines 20, which are equipped for grinding, are shown in
[0061] A gear cutting machine 20 details presented herein comprises, for example, as schematically shown in
[0062] Since this exemplary embodiment relates to a so-called single-indexing grinding method, the bevel gear workpiece 100 executes an indexing rotation B around the axis of rotation R2 after each machining of a flank of a tooth gap. It is thus a discontinuous method. Thus, for example, all concave flanks 5.1 of all teeth 5 are (fine) machined step-by-step (see
[0063] Furthermore, a computer 10 can be provided in all embodiments, which is especially designed (programmed) to apply the present method. The computer 10 has a communication connection to the machine 20 and/or the controller 50, as indicated in
[0064]
[0065] The single-spindle grinding machine 20 shown by way of example in
[0066] The single-spindle grinding machine 20 of
[0067] By way of the use of a suitable controller 50 and/or suitable software or a software module SW, the geometric accuracy of the hard-fine machining method (for example, of the grinding or the hard-skiving) can intentionally influence the machining result in comparison to lapping. The hard-fine machining thus becomes reproducible and is therefore also suitable above all for the fine machining in the series production of gear wheels and gear wheel pairs.
[0068] The noise behavior of gear wheels and gear wheel pairs is improved by the controller 50 and/or by suitable software or by a software module SW by the targeted change of the gear tooth geometry, wherein this is achieved by the avoidance of interfering periodicities. This means that periodic geometry components are eliminated by overlay of stochastic elements in all embodiments.
[0069] Due to the avoidance or due to the reduction of periodic patterns in the gear tooth geometry, the noise behavior and/or the subjective perception of the noise may be significantly improved.
[0070] The method presented herein is based, inter alia, on raising the background noise level, wherein a reduction thus occurs of the amplitudes of the tonal or periodic noise components, respectively, for example, the tooth engagement frequencies, in relation to the amplitudes of the background noise of the gear tooth noise.
[0071] The production of such tooth flank topographies varying from tooth to tooth can be achieved either by a variation of the tool profile (for example, of the profile 8 of a cup grinding wheel 2) or by a variation of the tool movement in relation to the tooth flank of the gear wheel workpiece by means of influencing of the machine kinematics during the production or finish machining of the tooth flank. However, a combination of the variation of tool geometry and machine kinematics can also be used in all embodiments.
[0072] For the practical application, solely a variation of the machine kinematics is used, as already described at the outset.
[0073] Preferably, only the machine axes which are already used in the basic kinematics to produce the geometry according to the main design, or which are used in any case during the conventional fine-hard machining, are used in at least some embodiments.
[0074] The method may especially be used for machining a gear wheel workpiece 100, which comprises multiple tooth gaps 6, which are each defined by two tooth flanks 5.1, 5.2 (see
[0075] For example, all concave tooth flanks 5.1 and/or all convex tooth flanks 5.2 can be machined or finish machined.
[0076] For example, all concave tooth flanks 5.1 of a subset of the tooth flanks and/or all convex tooth flanks 5.2 of a subset of the tooth flanks can be machined or finish machined.
[0077] The method may preferably be used on a multiaxis gear cutting machine 20, as shown by way of example in
[0078] Preferably, before the execution of the method, for example, in the scope of a design of the gear teeth, the tooth contact between the gear wheel workpiece 100 and a further gear wheel workpiece to be paired therewith is ascertained by computer by the use of software or a software module SW. The non-periodically distributed modification of the tooth contact is then predetermined for the contact of each tooth flank of the gear wheel workpiece 100 with each counter flank of the further gear wheel workpiece 1.
[0079] The method can be restricted in all embodiments to only the traction side of all or a part of all of the teeth. In addition, however, the method can also be applied in all embodiments to the thrust side.
[0080] The non-periodically distributed modification can be ascertained in all embodiments, for example, by means of flank generator software, before the method for (fine) machining is executed.
[0081] The machining is preferably executed in all embodiments so that an effective instantaneous transmission ratio, which does not have any periodically repeating oscillation components, results for a pairing of the gear wheel workpiece 100 with a second gear wheel workpiece.
[0082] Parameters of the gear teeth which are to be varied, and variation limits for each parameter, are preferably defined in all embodiments. To be able to produce the varied topographies of the tooth flanks without changing the tool profile, a restriction to the parameters of pressure angle and spiral angle suggests itself for crown gears which are produced in the plunging method.
[0083] Examples of the parameters and the variation limits thereof are indicated on the basis of the subsequent table:
TABLE-US-00001 Parameter Pinion Crown gear Pressure angle 0.020 0.020 Spiral angle 0.005 0.005 Vertical 0.004 mm crowning Longitudinal 0.006 mm crowning Torsion 0.030
[0084] It can be seen on the basis of this exemplary table that during the fine machining of the tooth flanks of crown gears produced in the plunging method, the pressure angle can be changed in the range of plus/minus 0.02 and the spiral angle can be changed in the range of plus/minus 0.005. This means that numerous various modifications of the tooth flanks, which do not periodically repeat, may be defined within these variation limits.
[0085] Individual parameter combinations, which each define a topography variant, are established within the variation limits of the individual parameters. The establishment can be performed randomly, for example.
[0086] As can be inferred from the table, in the case of pinions which are fine machined, in addition to the pressure angle and the spiral angle, the vertical crowning and/or the longitudinal crowning and/or the torsion can also be used for the variation of the flank topography, since the pinions are not machined by plunging in the single indexing method.
[0087] In the case of rolled crown gears, variations similar to pinions are possible.
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[0090] To be able to illustrate the stochastic distribution of the flank modifications, actually more than only two teeth of a correspondingly modified gear wheel workpiece 1 have to be shown. However, since an illustration according to
[0091] In the example shown in
[0092] The graphics of
[0093] On the left, exemplary numeric values are applied adjacent to the convex tooth of
[0094] Correspondingly, exemplary numeric values are also applied on the left adjacent to the convex tooth of
[0095] It can already be seen from these exemplary numbers that the convex tooth flank of the first tooth differs from the convex tooth flank of the further tooth.
[0096] As already mentioned, at least the tooth flanks on the traction side of the teeth are preferably occupied during the fine machining with a statistically distributed flank modification in all embodiments.
[0097] If both the traction side and also the thrust side of the flanks are stochastically changed, it is thus to be ensured that the values for the two flanks of a tooth gap are equal in absolute value, wherein they have the same sign for the spiral angle and the longitudinal crowning and they have opposite signs for the pressure angle, the vertical crowning, and the torsion, in order to enable an optimum production capability without change of the tool profile.
[0098] The number of the topography variants is preferably less than or equal to the number of teeth of the respective gear wheel workpiece in all embodiments. If the number is less than the number of teeth (for example, 10 variants with 45 teeth), it thus has to be established for the individual tooth gaps which variant is used. This establishment can be performed randomly in all embodiments.
[0099] For each topography variant, machine settings (if only small changes of the machine settings are used) and possibly the tool geometry data (if changes of the tool geometry are also used) are preferably ascertained as absolute values or difference values in relation to the basic design, using which they can be produced, in all embodiments. The topography variant can possibly only be approximated in this case. The individual tooth gaps of the gear wheel workpieces are produced according to these individual machine settings and possibly tool geometry data.
[0100] Based on the individual machine settings and possibly tool geometry data, the individual single tooth target topography is preferably defined in all embodiments for each topography variant.
[0101] To make the method of the fine machining more reproducible and robust, individual, multiple, or all tooth gaps are preferably measured in the machine tool 20 against the individual target topographies (called single tooth target topography) in all embodiments. If they become necessary, corrections of the machine settings of the machine tool 20 and possibly of the tool geometry data are then carried out as follows: [0102] individually for single tooth gaps or multiple tooth gaps having identical target topography to adapt these tooth gaps to the fundamental target topography, [0103] based on the deviations of single, multiple, or all tooth gaps in relation to the respective individual target topography as generally-valid correction to adapt all single topographies to the respective target topographies.
[0104] The method of at least some embodiments preferably comprises the subsequent steps in all embodiments: [0105] establishing a basic topography of all concave and/or convex tooth flanks of a gear wheel workpiece 1, [0106] establishing a topography variation, e.g., [0107] by loading previously stored specifications, [0108] by selecting (for example, on a computer 10) a suitable, previously defined topography variation, [0109] by the computer-assisted determination of a topography variation, [0110] by the definition of parameters and/or variation limits and the computer-assisted application of an algorithm [0111] computing/providing the individual target topographies of a part or all tooth flanks, [0112] computing/providing the corresponding machine kinematics and possibly changed tool data for topography of the tooth flank(s) of the part or all gaps, [0113] fine machining of the part or all tooth flanks (for example, by grinding), [0114] measuringpreferably within the machine tool 20 without re-chucking the gear wheel workpiece 1the current flank topographies against the individual target topographies, for example, to be able to ascertain deviations which are outside tolerances, [0115] if necessary, for example, because the actual topography of a flank is outside the tolerance in relation to the individual target topography, carrying out a correction machining of at least this one flank in the machine tool 20 without re-chucking the gear wheel workpiece 1.
[0116] It is to be noted here that at least a part of the preceding steps which were described above can also be executed in a different sequence. Thus, for example, in one substep, the machine kinematics can be provided or computed to then be able to determine the individual target topographies in a subsequent substep based on these machine kinematics. The individual target topographies which were determined from the machine kinematics can then be machined exactly in the machine 20.
[0117] While the above describes certain embodiments, those skilled in the art should understand that the foregoing description is not intended to limit the spirit or scope of the present disclosure. It should also be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure.